HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Takeda, K. Articles by Akira, S. Search for Related Content PubMed PubMed Citation Articles by Takeda, K. Articles by Akira, S.

Stat3 Activation Is Responsible for IL-6-Dependent T Cell Proliferation Through Preventing Apoptosis: Generation and Characterization of T Cell-Specific Stat3-Deficient Mice¹

Kiyoshi Takeda^*, Tsuneyasu Kaisho^*, Nobuaki Yoshida, Junji Takeda, Tadamitsu Kishimoto^§ and Shizuo Akira^2,*

^* Department of Biochemistry, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan; Research Institute, Osaka Maternal and Child Health Center, Izumi, Osaka, Japan; Department of Environmental Medicine, Osaka University Medical School, Osaka, Japan; and ^§ Osaka University, Suita, Osaka, Japan

	Abstract

Top Abstract Introduction Materials and Methods Results Discussion References

 
Stat3, a member of STAT, is activated by a variety of cytokines such as IL-6 family of cytokines, granulocyte CSF, epidermal growth factor, and leptin. A recent study with mice genetically deficient in the Stat3 gene has revealed its important role in the early embryogenesis. To assess the function of Stat3 in adult tissues, we disrupted the Stat3 gene specifically in T cells by conditional gene targeting using Cre-loxP system. In Stat3-deficient T cells, IL-6-induced proliferation was severely impaired. IL-6 did not enhance cell cycle progression, but prevented apoptosis of normal T cells. In contrast, IL-6 did not prevent apoptosis of Stat3-deficient T cells. Antiapoptotic protein, Bcl-2, was normally up-regulated in response to IL-6 even in Stat3-deficient T cells. These results demonstrate that Stat3 activation is involved in IL-6-dependent T cell proliferation through prevention of apoptosis independently of Bcl-2.

	Introduction

Top Abstract Introduction Materials and Methods Results Discussion References

 
Amember of STAT is a latent cytoplasmic transcription factor that mediates cytokine signal transduction (1, 2, 3, 4). Recent studies using mice deficient in STAT family members have revealed the essential role of STAT proteins in cytokine-mediated biologic functions (5, 6, 7, 8, 9, 10, 11, 12, 13). STAT proteins were recognized initially as transcription factors that were involved in expressions of specific genes, but not required for cell proliferation (3, 14). However, Stat4- and Stat6-deficient mice were severely impaired in IL-12- and IL-4-induced proliferation of T cells, respectively. In addition, studies with the mutated erythropoietin receptor and the dominant negative Stat5 protein demonstrated that Stat5 is crucial for erythropoietin- and IL-3-dependent cell proliferation, respectively (15, 16, 17). Stat5a-deficient mice were defective in IL-2-induced T cell proliferation due to the impaired expression of the IL-2R -chain (18). Stat1 has been shown to be involved in cell cycle arrest through induction of p21^WAF1 (19). Stat6 and Stat4 have been shown to be involved in cell cycle control by regulating p27^Kip1 expression. (20). Furthermore, Stat1, Stat3, and Stat5 have been shown to be constitutively phosphorylated in Src-transformed cell lines (21, 22). Thus, several lines of evidences indicate that STAT proteins are involved in cell proliferation.

Stat3 was identified originally as an acute phase response factor that was tyrosine phosphorylated by IL-6 (23, 24). Stat3 has been shown to be activated by a variety of cytokines. These include IL-6 family of cytokines, granulocyte CSF, epidermal growth factor, IFN-, leptin, IL-2, and IL-10 (1, 25). Constitutive activation of Stat3 has been observed in several T cell leukemias, indicating the important role of Stat3 in T cell oncogenesis or proliferation (26, 27, 28, 29, 30). However, it remains unclear how Stat3 activation contributes to proliferation of T cells.

We previously intended to generate Stat3-deficient mice to examine the in vivo role of Stat3. Stat3-deficient mice unexpectedly died during their early embryogenesis (31). Therefore, in an attempt to assess the role of Stat3 in T cells, we have utilized Cre-loxP recombination system to generate mice in which Stat3 is deficient in T cell-specific manner (32, 33, 34, 35). We first generated floxed-Stat3 mice, in which two loxP sites were introduced into 5' and 3' of exon encoding tyrosine residue critical for STAT activation. Floxed-Stat3 mice were mated with transgenic mice expressing Cre recombinase specifically in T cells under the control of Lck promoter (33, 36). T cells from these mice displayed the severely impaired proliferative response to IL-6 plus costimuli. The severely impaired IL-6-induced T cell proliferation was due to the profound defect in IL-6-mediated prevention of apoptosis in Stat3-deficient T cells. However, antiapoptotic protein, Bcl-2, was normally expressed in Stat3-deficient T cells. These data indicate that IL-6-induced Stat3 activation is indispensable for antiapoptotic signal independently of Bcl-2, resulting in enhanced T cell proliferation.

	Materials and Methods

Top Abstract Introduction Materials and Methods Results Discussion References

 
Construction of the targeting vector

A targeting vector was constructed to delete exon 22, which encodes tyrosine residue essential for STAT activation. The SpeI-HindIII-digested 3-kb fragment of the Stat3 genomic DNA containing exon 21 was inserted between two loxP sites of the vector pKSTKNEOLOXP, which has herpes simplex virus thymidine kinase and loxP-flanked pGK-neo. Then the 1-kb genomic fragment 5' upstream of exon 21 and 3' downstream HindIII-HindIII 5-kb genomic fragment were inserted.

Generation of floxed-Stat3 mice

The linearized targeting vector was electroporated into E14.1 embryonic stem (ES)³ cells. The doubly resistant clones to G418 and ganciclovir were screened for homologous recombination by PCR. The correctly targeted clones were confirmed by Southern blot analysis with the probe indicated in Figure 1A. One of the targeted clones was then transiently transfected with pIC-Cre to delete pGK-neo gene flanked by two loxP sites (32). The clones that became sensitive to G418 were subjected to Southern blot analysis to detect Stat3 flox and Stat3 clones. Three Stat3 flox ES clones were microinjected into C57BL/6 blastocysts to generate chimeric mice. Two chimeric mice successfully transmitted the germline. (Stat3^flox/+)F₁ mice were intercrossed to generate Stat3^flox/flox mice.

View larger version (32K): [in this window] [in a new window]   FIGURE 1. Generation of T cell-specific Stat3-deficient mice. A, Construction of the targeting vector. a, Genomic structure of the mouse Stat3 gene. b, The targeting vector. Exon 21 was flanked by two loxP sequences. Third loxP sequence was introduced to flank neo gene. c, The targeted allele contained three loxP sequences and neo gene. Cre-mediated deletion was expected to produce Stat3flox allele (d) and Stat3 allele (e). Solid triangle denotes loxP sequence. E, EcoRI; H, HindIII. B, Southern blot analysis of thymocytes. DNA was extracted from thymocytes from the indicated mice, electrophoresed, transferred to nylon membrane, and hybridized with the probe indicated in A. C, Western blot analysis of thymocytes and liver cells. Lysates from 1 x 107 cells stimulated with IL-6 for 30 min were immunoprecipitated with anti-Stat3 Ab, and immunoblotted with anti-phosphotyrosine Ab (-PY) or anti-Stat3 Ab. D, Nucleotide sequence and predicted amino acid pattern of the RT-PCR products from thymocytes of Lck-Cre/Stat3flox/- mice.

Lck-Cre transgenic mice (36) were bred with formerly generated Stat3-deficient mice to generate mice carrying lck-cre and heterozygous Stat3 (Lck-Cre/Stat3^+/-) genes. These mice were mated with Stat3^flox/flox or Stat3^flox/+ mice. Offspring carrying lck-cre and floxed Stat3 genes (Lck-Cre/Stat3^flox/+ or Stat3^flox/-) and wild-type Stat3 gene (Lck-Cre/Stat3^+/+ or Lck-Cre/Stat3^+/-) were used for further analysis.

Western blot analysis

Thymocytes or Con A-activated splenic T cells (2 x 10⁷) were stimulated with the indicated cytokines for 30 min. IL-2, IL-6, and IL-7 were purchased from Genzyme (Cambridge, MA). Leukemia-inhibitory factor (LIF) was from Life Technologies (Grand Island, NY), and oncostatin M was from R&D Systems (Minneapolis, MN). Cells were solubilized with ice-cold lysis buffer containing 0.5% Nonidet P-40, 10 mM Tris-HCl (pH 7.4), 150 mM NaCl, 1 mM EDTA, 0.2 mM PMSF, 1 mM Na₃VO₄, and 5 µg/ml aprotinin. Whole cell lysates were incubated with Ab to Stat3 (C-20) (Santa Cruz Biotechnology, Santa Cruz, CA) or Stat5b (C-17; this Ab recognizes both Stat5a and Stat5b) (Santa Cruz Biotechnology) and protein A-Sepharose (Pharmacia, Uppsala, Sweden) for 4 h at 4°C. Immunoprecipitates were separated on SDS-polyacrylamide gel, transferred to a nitrocellulose membrane, and incubated with anti-phosphotyrosine mAb (4G10; Upstate Biotechnology, Lake Placid, NY). Bound Ab was visualized with an enhanced chemiluminescence system (DuPont, Boston, MA).

Preparation of splenic T cells

Splenic T cells were purified as described previously (8). Briefly, splenic T cells were enriched by nylon wool column passage. Enriched T cells were incubated with anti-I-Ab mAb for 30 min on ice, then washed, and incubated with rabbit complement (Low-Tox-M; Cedar Lane, Ontario, Canada) for 30 min at 37°C. Purified T cells were analyzed by staining with FITC-conjugated anti-CD3 mAb (PharMingen, San Diego, CA), and >95% CD3-positive cells were used for experiments.

T cell proliferation assay

Thymocytes (1 x 10⁵) or splenic T cells (5 x 10⁴) were cultured in 96-well plates in the presence of the indicated cytokines and/or mitogens for 72 h. A quantity amounting to 1 µCi of [³H]thymidine was pulsed for the last 12 h. Concentrations of cytokines and mitogens used in this assay were as follows: IL-2, 20 ng/ml; IL-6, 10 ng/ml; IL-7, 10 ng/ml (Genzyme); anti-CD3 Ab, 100 ng/ml (PharMingen); PMA, 10 ng/ml; Con A, 2.5 µg/ml; and calcium ionophore, 10 µM (Sigma, St. Louis, MO).

In the case of inhibition of IL-2-induced proliferation, 20 µg/ml of anti-IL-2-neutralizing Ab (Genzyme, Cambridge, MA) was added in the cell cultures.

Flow-cytometric analysis

Cells were stained with biotin-conjugated anti-IL-6R mAb following FITC-streptavidin, or rat anti-gp130 mAb following FITC-conjugated anti-rat Ig. These Abs were purchased from PharMingen. Rat anti-gp130 mAb was kindly provided by Dr. T. Taga (37). Stained cells were analyzed on FACSCalibur using CellQuest software (Becton Dickinson, Lincoln Park, NJ).

Cell cycle analysis

Splenic T cells were cultured with 10 ng/ml IL-6 and/or 100 ng/ml anti-CD3 Ab for 48 h in the presence or absence of 20 µg/ml anti-IL-2 Ab (Genzyme) plus 10 µg/ml anti-IL-2R Ab (clone 3C7; PharMingen). At 48-h culture period, cells were harvested, washed, and fixed in 70% ethanol for 1.5 h at -20°C. Fixed cells were pelleted, incubated in 1 ml of 50 µg/ml RNase for 20 min at 37°C, and washed. Then cells were suspended with 50 µg/ml propidium iodide (PI), incubated for 5 min at room temperature, and analyzed on FACSCalibur (Becton Dickinson).

Detection of apoptotic cells

Splenic T cells were cultured in RPMI 1640 containing 0.1% FCS with or without 10 ng/ml IL-6 or 100 ng/ml anti-CD3 Ab for 5 h. Cells were harvested, washed, and stained with annexin V and PI, according to the manufacturer’s instructions (R & D Systems). Cells were analyzed on FACSCalibur.

Intracellular staining

Thymocytes or splenic T cells were cultured with or without 10 ng/ml IL-6 for 3 days. Cells were stained with Cy-Chrome-conjugated anti-CD4 mAb and phycoerythrin-conjugated anti-CD8 mAb (PharMingen), and washed. Cells were resuspended with 100 µl of PBS containing 4% paraformaldehyde, incubated for 20 min on ice, and washed. Then cells were resuspended with 50 µl of PBS containing 1% FCS, 0.1% sodium azide, 0.1% saponin (Sigma), and 5 µg/ml hamster anti-Bcl-2 mAb (PharMingen). After 30-min incubation on ice, cells were washed and further stained with FITC-conjugated anti-hamster Ig (Vector, Burlingame, CA) for 30 min on ice. Cells were analyzed on FACSCalibur. In the case of Bcl-xl, cells were incubated with mouse anti-Bcl-xl mAb (Transduction Laboratories, Lexington, KY), followed by FITC-conjugated goat anti-mouse IgG (Immunotech, Marseille, France).

RT-PCR analysis

Splenic T cells (1 x 10⁷) were cultured with or without 100 ng/ml of IL-6 for 3 h. Total RNA was extracted with TRIzol reagent (Life Technologies), reverse transcribed with Superscript II (Life Technologies), and amplified by PCR using primers specific for the mouse Bcl-2, Bcl-xl, BAG-1, and ß-actin gene.

	Results

Top Abstract Introduction Materials and Methods Results Discussion References

 
Generation of floxed-Stat3 mice

Inactivation of the Stat3 gene in ES cells by the classical targeting method led to early embryonic lethality and could not reveal its role in adult tissues or organs (31). To clarify the function of Stat3 in T cells, we utilized the Cre-loxP system for disruption of the Stat3 gene (32, 33). A target vector was constructed so that Stat3 tyrosine phosphorylation site could be deleted by expression of Cre protein. The neomycin resistance (neo) gene flanked by two loxP sites were introduced into intron 21 of the Stat3 gene (Fig. 1A). An additional loxP site was inserted into intron 22. The herpes simplex virus thymidine kinase was ligated at the 5' end of the homologous region. ES cells were electroporated with this vector and selected in the presence of G418 and ganciclovir. Homologous recombinant clones were identified by PCR and confirmed by Southern blot analysis.

Cre protein was transiently expressed in the targeted ES clones to delete the loxP-flanked neo gene. Two types of clones, Stat3 flox and Stat3, were expected from ES clones that became sensitive to G418 (Fig. 1A). However, Stat3 clones could not be obtained, although Stat3 flox ES clones could be easily obtained. Several G418-sensitive ES clones showed the apparently differentiated morphology, and most of them displayed Stat3 genotype by Southern blot analysis, supporting the previous finding that the Stat3 protein lacking the tyrosine phosphorylation site acts as a dominant negative form and induces differentiation of ES cells even in the presence of LIF (38, 39).

The Stat3 flox ES clones were used to generate chimeric mice, which successfully contributed the germline transmission. Mice homozygous for the loxP-flanked (floxed) Stat3 gene (Stat3^flox/flox) were born at the expected Mendelian ratios and presented no obvious abnormalities.

Generation of T cell-specific Stat3-deficient mice

To generate mice in which Stat3 was deficient in T cell-specific manner, Stat3^flox/flox mice were mated to mice carrying both the Cre transgene under the lck promoter and the heterozygous Stat3 gene (Lck-Cre/Stat3^+/-). Mice with Lck-Cre and the floxed-Stat3 gene (Lck-Cre/Stat3^flox/+ or Lck-Cre/Stat3^flox/-) were born alive and grew healthy. To evaluate the efficiency of the Cre-mediated deletion of the floxed gene, we performed Southern blot analysis of thymocytes (Fig. 1B). In thymocytes from nontransgenic floxed-Stat3 mice, 8-kb band was detected. In thymocytes from Lck-Cre/Stat3^flox/+ or Lck-Cre/Stat3^flox/- mice, the 8-kb band disappeared, but a 4.1-kb band corresponding to Stat3 allele appeared. Thus, complete Cre-mediated deletion occurred in thymocytes of Lck-Cre/floxed-Stat3 mice at DNA level. We next analyzed the Cre-mediated deletion at protein level (Fig. 1C). Thymocytes were stimulated with IL-6 for 30 min, lysed, and incubated with anti-Stat3 Ab, which recognizes C-terminal portion of Stat3 protein. Immunoprecipitants were Western blotted by anti-phosphotyrosine or anti-Stat3 Ab. Stat3 protein was readily detected in thymocytes from mice carrying wild-type allele of Stat3 locus (lck;+/+ and lck;flox/+). However, only a little amount of Stat3 protein was observed in thymocytes from Lck-Cre/Stat3^flox/- mice. In addition, a protein band with slightly decreased m.w. was detected in Lck-Cre/Stat3^flox/- or Lck-Cre/Stat3^flox/+ mice (Fig. 1C, middle). To precisely analyze this protein, we performed RT-PCR analysis with total RNA from thymocytes of Lck-Cre/Stat3^flox/- mice. The RT-PCR products from thymocytes of Lck-Cre/Stat3^flox/- mice consisted of two bands with different sizes. The length of the longer band corresponds to normal Stat3 protein. Sequence analysis of the shorter band revealed the lack of the region encoding exon 21 and a part of exon 22 from normal Stat3 cDNA (Fig. 1D). Thus, Cre-mediated deletion led to the production of a truncated form of Stat3 protein (Stat3 protein). This Stat3 protein contained no tyrosine residue and mitogen-activated protein/kinase recognition site, both of which are important for STAT activation.

IL-6 stimulation of thymocytes from Lck-Cre/Stat3^flox/- mice did not induce phosphorylation of Stat3 protein, although a small amount of wild-type Stat3 protein was detected (Fig. 1C, top). In addition, activation of Stat3 was severely reduced in thymocytes of Lck-Cre/Stat3^flox/+ mice, in which wild-type Stat3 protein abundantly existed, indicating that the truncated Stat3 protein acts as a dominant negative form for activation of Stat3. Production or phosphorylation of Stat3 protein in liver cells was not affected in Lck-Cre/Stat3^flox/- mice, indicating that Cre-mediated deletion of the floxed gene occurred specifically in T cells (Fig. 1C, bottom).

We next analyzed whether dominant negative Stat3 protein affects activation of Stat5 protein. Thymocytes from control and mutant mice were stimulated with IL-2 or IL-7, and Stat5 activation was analyzed. As shown in Figure 2A, Stat5 was equally phosphorylated in response to IL-2 or IL-7 in thymocytes of Lck-Cre/Stat3^flox/+ or Lck-Cre/Stat3^flox/- mice when compared with nontransgenic mice, demonstrating that Stat5 proteins were normally activated in these mice (Fig. 2A).

View larger version (50K): [in this window] [in a new window]   FIGURE 2. Western blot analysis. A, Thymocytes from the indicated mice were stimulated with IL-2 or IL-7 for 30 min, lysed, and incubated with anti-Stat5 Ab, which recognizes both Stat5a and Stat5b. Immunoprecipitates were blotted with anti-phosphotyrosine Ab (-PY), and reblotted with anti-Stat5 Ab. B, Thymocytes were stimulated with the indicated cytokines for 30 min. Splenic T cells were cultured with 2.5 µg/ml of Con A for 3 days, starved in 0.1% FCS medium for 2 h, and stimulated with IL-2 for 30 min. Cells were lysed, incubated with anti-Stat3 Ab, and immunoblotted with anti-phosphotyrosine Ab.

We examined whether the abrogation of Stat3 activation affects T cell development. Total nucleated cell numbers of lymphoid organs such as thymus, spleen, and lymph nodes in Lck-Cre/Stat3^flox/- mice were almost the same as those in Lck-Cre;+/+ mice (data not shown). In addition, flow-cytometric analysis of these organs revealed that CD3-positive T cell population and CD4/CD8 ratios in T cells of Lck-Cre/Stat3^flox/- mice were not altered as compared with Lck-Cre;+/+ mice (data not shown). These results indicate that Stat3 activation is not involved in development and intrinsic maintenance of T cells.

Growth of Stat3-deficient T cells in response to cytokines

We analyzed Stat3 activation by cytokines in T cells (Fig. 2B). Stat3 was phosphorylated by IL-6 family of cytokines such as IL-6, LIF, and oncostatin M in thymocytes. In addition, Stat3 was phosphorylated in response to IL-7, which has been shown to activate Stat5. Although IL-2-induced Stat3 phophorylation was faint in freshly isolated thymocytes or splenic T cells, IL-2-induced phosphorylation of Stat3 was more clearly observed in Con A-activated splenic T cells. Thus, Stat3 is demonstrated to be activated by IL-6, LIF, oncostatin M, IL-2, and IL-7 in T cells.

We then examined proliferation of T cells in response to these cytokines in Lck-Cre/Stat3^flox/- mice. We first examined the effect of Stat3 deficiency upon IL-6-induced T cell proliferation. Thymocytes from Lck-Cre;+/+ mice displayed the increased proliferation in response to stimulation with IL-6 plus anti-CD3 Ab. However, thymocytes from Lck-Cre/Stat3^flox/- mice did not show any enhanced proliferation in response to IL-6 plus anti-CD3 Ab (Fig. 3A). Similarly, splenic T cells from Lck-Cre;+/+ mice showed the increased proliferative response when stimulated with IL-6 plus Con A, whereas proliferation of splenic T cells from Lck-Cre/Stat3^flox/- mice in response to IL-6 plus Con A was severely impaired (Fig. 3B). Thus, IL-6-induced proliferation was severely impaired in T cells from Lck-Cre/Stat3^flox/- mice.

View larger version (43K): [in this window] [in a new window]   FIGURE 3. Cytokine-induced proliferation of T cells. A, Thymocytes were cultured with the indicated stimulation for 72 h. [3H]Thymidine was pulsed for the last 12 h. Concentration of each stimulation was indicated in Materials and Methods. B, Splenic T cells were cultured with the indicated stimulation for 72 h. 3H uptake was measured.

IL-6 is not directly involved in cell cycle progression in T cells

We next investigated the molecular mechanism of impaired IL-6-induced proliferation of T cells from Lck-Cre/Stat3^flox/- mice. We first examined the expression of the receptors for IL-6 on the surface of T cells. Flow-cytometric analysis of splenic T cells was performed using mAb against IL-6R and gp130, a signal transducer of IL-6. Expression of IL-6R and gp130 was not altered between T cells from Lck-Cre;+/+ and Lck-Cre/Stat3^flox/- mice (Fig. 4). In addition, in vitro IL-6 stimulation did not increase the expression of both receptors in Lck-Cre;+/+ and Lck-Cre/Stat3^flox/- T cells (data not shown). These indicate that lack of IL-6 response in Stat3-deficient T cells is not a result of the reduced expression of the receptors. We next examined whether proliferation of T cells in response to IL-6 plus anti-CD3 Ab or Con A is due to the increased production of IL-2, a potent growth factor for T cells. As shown in Figure 5A, treatment with anti-IL-2 Ab did not reduce the proliferative response to IL-6 plus anti-CD3 Ab, indicating that IL-6-induced T cell proliferation is not a result of the increased IL-2 production from T cells.

View larger version (27K): [in this window] [in a new window]   FIGURE 4. Normal expression of the IL-6R complex on T cells from Lck-Cre/Stat3flox/- mice. Splenic T cells from wild-type and Lck-Cre/Stat3flox/- mice were stained with anti-IL-6R Ab (left) or anti-gp130 Ab (right), followed by FITC-conjugated second Ab.

View larger version (20K): [in this window] [in a new window]   FIGURE 5. Involvement of IL-6 in T cell proliferation. A, Wild-type splenic T cells were cultured with the indicated stimulation in the presence or absence of 20 µg/ml anti-IL-2-neutralizing Ab. 3H uptake was measured. B, Wild-type splenic T cells were cultured with 10 ng/ml IL-6 and/or 100 ng/ml anti-CD3 Ab for 48 h in the presence or absence of anti-IL-2 Ab plus anti-IL-2R Ab. Then cells were fixed and stained with PI. Percentage of the population in S phase and G2/M phase was shown.

IL-6 does not prevent apoptosis of Stat3-deficient T cells

We next analyzed whether IL-6 could rescue apoptosis of T cells by staining with both PI and annexin V (Fig. 6). Apoptotic cells become annexin V positive at its early phase due to the loss of cell membrane phospholipid asymmetry, and then become PI positive. In vitro 5-h culture of Lck-Cre;+/+ T cells in 0.1% FCS showed about 40% (33 + 6.2%) of annexin V-positive apoptotic cells. Treatment with anti-CD3 Ab did not cause a significant change. In contrast, addition of IL-6 significantly decreased the population of annexin V-positive cells. This demonstrates that IL-6 rescues in vitro cultured T cells from apoptotic cell death. However, addition of IL-6 did not lead to any reduction of annexin V-positive T cells from Lck-Cre/Stat3^flox/- mice, demonstrating that Stat3-deficient T cells are devoid of IL-6-mediated antiapoptotic response. Thus, our results demonstrate that IL-6-induced Stat3 activation is essential for IL-6-mediated antiapoptotic response.

View larger version (45K): [in this window] [in a new window]   FIGURE 6. IL-6-induced prevention of T cell apoptosis was impaired in Lck-Cre/Stat3flox/- mice. Splenic T cells from wild-type and Lck-Cre/Stat3flox/- mice were cultured in 0.1% FCS culture medium in the presence of 10 ng/ml IL-6 and/or 100 ng/ml anti-CD3 Ab for 5 h. Then cells were stained with FITC-annexin V and PI.

Bcl-2 has been shown to protect T cells against several apoptotic stimuli. Indeed, Bcl-2-deficient mice displayed the shortened life span of T cells (40). Therefore, we examined whether expression of Bcl-2 is defective in Stat3-deficient T cells. Thymocytes or splenic T cells were cultured with or without IL-6 for 3 days, and Bcl-2 expression was analyzed by intracellular staining with anti-Bcl-2 Ab. Bcl-2 expression was up-regulated by IL-6 in CD4^- single-positive, CD8^- single-positive, and double-negative thymocytes of Lck-Cre;+/+ mice (Fig. 7A). Bcl-2 expression was also up-regulated by IL-6 in splenic T cells of Lck-Cre;+/+ mice (Fig. 7A). Interestingly, IL-6 stimulation of thymocytes and splenic T cells from Lck-Cre/Stat3^flox/- mice normally up-regulated Bcl-2 expression. Thus, Stat3-deficient T cells displayed normal IL-6-induced Bcl-2 expression, although these cells were devoid of IL-6-induced enhancement of cell survival. Other Bcl-2-related proteins, such as Bcl-xl and BAG-1, are also shown to be responsible for the prevention of apoptosis of lymphocytes (41, 42, 43). Flow-cytometric analysis revealed that expression of Bcl-xl was not enhanced in splenic T cells cultured in medium alone or IL-6, although dramatically enhanced by stimulation with IL-2 in wild-type mice (Fig. 7B). RT-PCR analysis demonstrated that mRNA expression of BAG-1 and Bcl-xl was not augmented by IL-6 in splenic T cells from wild-type and Lck-Cre/Stat3^flox/- mice (Fig. 7C). Thus, IL-6 did not enhance the expression of Bcl-xl or BAG-1 in T cells, indicating that both proteins are not involved in IL-6-mediated antiapoptotic activity. Taken together, our results indicate that IL-6-induced Stat3 activation is responsible for antiapoptotic signals independently of Bcl-2 or its related proteins.

View larger version (27K): [in this window] [in a new window]   FIGURE 7. Normal IL-6-induced Bcl-2 expression in T cells of Lck-Cre/Stat3flox/- mice. A, Thymocytes or splenic T cells were cultured with or without 10 ng/ml IL-6 for 72 h. Cells were intracellularly stained for Bcl-2, as described in Materials and Methods. B, Wild-type splenic T cells were cultured with 10 ng/ml IL-6 or IL-2 for 72 h. Cells were stained for Bcl-xl and analyzed by flow cytometry. C, Splenic T cells were cultured with or without 100 ng/ml IL-6 for 3 h. Total RNA was extracted, reverse transcribed, and PCR amplified with primers specific for the indicated genes.

	Discussion

Top Abstract Introduction Materials and Methods Results Discussion References

IL-6-induced Stat3 activation is responsible for antiapoptotic signal in T cells

Costimulation with IL-6 and anti-CD3 Ab did not enhance proliferation of Stat3-deficient T cells. Although IL-6 has been shown to be a costimulant for T cell proliferation, IL-6 itself did not have a mitogenic activity for T cells (46). Indeed, IL-6 did not induce any progression of cell cycle in T cells. We first suspected that the severely impaired IL-6-induced proliferation of Stat3-deficient T cells might be due to the impaired IL-2 production, because anti-CD3 Ab- or Con A-stimulated T cells produce IL-2. However, anti-IL-2-neutralizing Ab did not reduce proliferation of T cells stimulated with IL-6 and anti-CD3 Ab, demonstrating that the impaired IL-6-induced proliferation of Stat3-deficient T cells was not a result of the impaired IL-2 production. In addition, two components for the IL-6R complex, IL-6R and gp130, were normally expressed on the surface of Stat3-deficient T cells, indicating that the impaired IL-6-induced T cell proliferation was not a result of defective IL-6R expression. This is unlike the case in Stat5a-deficient mice, which were defective in IL-2-induced T cell proliferation due to the impaired IL-2-induced IL-2R -chain (18). Recently, IL-6 has been shown to inhibit apoptosis of resting T cells (47). These facts prompted us to hypothesize that IL-6-induced prevention of T cell apoptosis contributes to the enhanced proliferation of anti-CD3 Ab-stimulated T cells. As expected, IL-6 rescued in vitro cultured T cells from apoptosis. Moreover, IL-6 did not prevent apoptosis of Stat3-deficient T cells. Thus, our results demonstrate that IL-6-induced Stat3 activation is critically involved in prevention of T cell apoptosis, and further indicate that the activity of IL-6 as a costimulant for T cell proliferation attributes to the prevention of T cell apoptosis through Stat3 activation.

We further examined whether IL-6-mediated Stat3 activation induces expression of the antiapoptosis-related genes. Bcl-2 is a well-characterized protein that prevents apoptosis in lymphocytes. Bcl-2 is shown to be expressed in peripheral T cells, CD4⁺, CD8⁺, and CD4^-CD8^- thymocytes, but not in CD4⁺CD8⁺ thymocytes, which are exposed to the programmed cell death under negative selection of T cell development (48, 49). T cells from Bcl-2-deficient mice were highly sensitive to apoptosis (40, 50, 51). In addition, decreased Bcl-2 expression was observed in IL-7- or IL-7R-deficient mice, which displayed the profound decrease in T and B cells (52). From these findings, we speculated that cytokine-induced Bcl-2 expression is important for prevention from apoptosis of in vitro cultured T cells. Indeed, stimulation with IL-2, IL-7, or IL-6 up-regulated Bcl-2 expression and increased the survival of T cells from wild-type mice (data not shown). Surprisingly, IL-6 normally up-regulated Bcl-2 expression even in Stat3-deficient T cells, in which IL-6-induced prevention of apoptosis was not observed. These findings imply that Stat3 activation is involved in IL-6-mediated antiapoptotic activity independently of Bcl-2. Expression of other Bcl-2-related antiapoptotic proteins, such as Bcl-xl and BAG-1, was not induced by IL-6 stimulation. Therefore, IL-6-mediated Stat3 activation may induce expression of as yet unidentified antiapoptotic genes.

STAT activation in lymphocyte proliferation

The involvement of STAT proteins in lymphocyte proliferation has been discussed in several knockout mice of STAT family (7, 8, 9, 10, 11, 18, 20). First, proliferation of lymphocytes in responses to IL-4 and IL-12 has been shown to be impaired in Stat6- and Stat4-deficient mice, respectively (7, 8, 9, 10, 11). But, it remained controversial how STAT proteins are involved in proliferation. However, recent studies have revealed the mechanisms for the regulation of cell proliferation by STAT proteins. Stat5a-deficient mice have been shown to be defective in IL-2-mediated T cell proliferation due to the impaired IL-2-induced IL-2R -chain expression (18). This study implies that STAT proteins indirectly control lymphocyte proliferation through expressions of genes that are necessary for cell proliferation. In contrast, the study using Stat4- and Stat6-deficient mice has demonstrated that these mice were not defective in expression of the receptor, but impaired in IL-12- and IL-4-induced down-regulation of expression of p27^Kip1, one of the inhibitors of cyclin-dependent kinases (CDK) that progress cell cycle (20). Similarly, Stat1 has been shown to regulate cell cycle machinery in nonlymphoid cells through IFN-induced expression of p21^WAF1, another inhibitor of CDK (19). These studies imply that STAT proteins control cell cycle through regulating expression of CDK inhibitors. Our present study demonstrates that IL-6-induced Stat3 activation does not directly progress cell cycle; however, it is indispensable for prevention of apoptosis, resulting in enhanced cell proliferation. Thus, studies using knockout mice have established that STAT proteins regulate cell proliferation through distinct mechanisms, such as gene expressions responsible for cell proliferation, regulation of CDK inhibitor expression, and prevention of apoptosis.

In addition to impaired IL-6-induced proliferation, T cells from Lck-Cre/Stat3^flox/- mice displayed partial defect in IL-2-induced T cell proliferation. We observed partial impairment in IL-2-induced IL-2R expression in Lck-Cre/Stat3^flox/- T cells (unpublished data). This indicates that the defective IL-2-induced T cell proliferation is due to the defective IL-2-induced IL-2R expression, like the case of Stat5a-deficient mice (18). However, high concentration of IL-2 induced normal expression of IL-2R in Lck-Cre/Stat3^flox/- T cells, and these T cells proliferated as well as wild-type T cells in response to IL-2 (unpublished data). These may explain the normal population of peripheral T cells in Lck-Cre/Stat3^flox/- mice.

Constitutive activation of Stat3 was observed in several T cell leukemias, such as adult T cell leukemia, Sezary syndrome, and mycosis fungoides (26, 27, 28, 29, 30). Stat3 activation in T cells, as demonstrated in this study, may contribute to immortalization of T cells and finally to T cell oncogenesis. Inhibition of Stat3 activation may be an effective therapeutic maneuver for these T cell leukemias.

	Acknowledgments

 
We thank T. Taga for providing anti-gp130 mAb, W. Reith for providing pKSTKNEOLOXP plasmid, Y. Kataoka for technical assistance, and T. Aoki for secretarial assistance.

	Footnotes

 
¹ This work was supported by CREST (Core Research for Evolutional Science and Technology) of Japan Science and Technology Corporation (JST) and by grants from the Ministry of Education of Japan.

² Address correspondence and reprint requests to Dr. Shizuo Akira, Department of Biochemistry, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, 663-8501, Japan. E-mail address:

³ Abbreviations used in this paper: ES, embryonic stem; CDK, cyclin-dependent kinase; LIF, leukemia-inhibitory factor; PI, propidium iodide.

Received for publication April 6, 1998. Accepted for publication June 29, 1998.

	References

Top Abstract Introduction Materials and Methods Results Discussion References

 

1. Schindler, C., Jr J. E. Darnel. 1995. Transcriptional responses to polypeptide ligands: the Jak-STAT pathway. Annu. Rev. Biochem. 64:621.[Medline]
2. Jr Darnell, J. E.. 1997. STATs and gene regulation. Science 277:1630.[Abstract/Free Full Text]
3. Ihle, J. N.. 1996. STATs: signal transducers and activators of transcription. Cell 84:331.[Medline]
4. O’Shea, J. J.. 1997. Jaks, STATs, cytokine signal transduction, and immunoregulation: are we there yet?. Immunity 7:1.[Medline]
5. Durbin, J. E., R. Hackenmiller, M. C. Simon, D. E. Levy. 1996. Targeted disruption of the mouse Stat1 gene results in compromised innate immunity to viral disease. Cell 84:443.[Medline]
6. Meraz, M. A., J. M. White, K. C. Sheehan, E. A. Bach, S. J. Rodig, A. S. Dighe, D. H. Kaplan, J. K. Riley, A. C. Greenlund, D. Campbell, K. Carver-Moore, R. N. DuBois, R. Clark, M. Aguet, R. D. Schreiber. 1996. Targeted disruption of Stat1 gene in mice reveals unexpected physiologic specificity in the JAK-STAT signaling pathway. Cell 84:431.[Medline]
7. Shimoda, K., J. van Deursen, M. Y. Sangster, S. R. Sarawar, R. T. Carson, R. A. Tripp, C. Chu, F. W. Quelle, T. Nosaka, D. A. A. Vignali, P. C. Doherty, G. Grosveld, W. E. Paul, J. N. Ihle. 1996. Lack of IL-4-induced Th2 response and IgE class switching in mice disrupted Stat6 gene. Nature 380:630.[Medline]
8. Takeda, K., T. Tanaka, W. Shi, M. Matsunoto, M. Minami, S. Kashiwamura, K. Nakanishi, N. Yoshida, T. Kishimoto, S. Akira. 1996. Essential role of Stat6 in IL-4 signalling. Nature 380:627.[Medline]
9. Kaplan, M. H., U. Schindler, S. T. Smiley, M. J. Grusby. 1996. Stat6 is required for mediating responses to IL-4 and for development of Th2 cells. Immunity 4:313.[Medline]
10. Kaplan, M. H., Y. L. Sun, T. Hoey, M. J. Grusby. 1996. Impaired IL-12 responses and enhanced development of Th2 cells in Stat4-deficient mice. Nature 382:174.[Medline]
11. Thierfelder, W. E., J. M. van Deursen, K. Yamamoto, R. A. Tripp, S. R. Sarawar, R. T. Carson, M. Y. Sangster, D. A. Vignali, P. C. Doherty, G. C. Grosveld, J. N. Ihle. 1996. Requirement for Stat4 in interleukin-12-mediated responses of natural killer and T cells. Nature 382:171.[Medline]
12. Liu, X., G. W. Robinson, K. Wagner, L. Garrett, A. Wynshaw-Boris, L. Hennighausen. 1997. Stat5a is mandatory for adult mammary gland development and lactogenesis. Genes Dev. 11:179.[Abstract/Free Full Text]
13. Udy, G. B., R. P. Towers, R. G. Snell, R. J. Wilkins, S. Park, P. A. Ram, D. J. Waxman, H. W. Davey. 1997. Requirement of STAT5b for sexual dimorphism of body growth rates and liver gene expression. Proc. Natl. Acad. Sci. USA 94:7239.[Abstract/Free Full Text]
14. Quelle, F. W., K. Shimoda, W. Thierfelder, C. Fischer, A. Kim, S. N. Ruben, J. L. Cleveland, J. H. Pierce, A. D. Keegan, K. Nelms, W. E. Paul, J. N. Ihle. 1995. Cloning of murine Stat6 and human Stat6, Stat proteins that are tyrosine phosphorylated in response to IL-4 and IL-3 but are not required for mitogenesis. Mol. Cell. Biol. 15:3336.[Abstract]
15. Damen, J. E., H. Wakao, A. Miyajima, J. Krosl, R. K. Humphries, R. L. Cutler, G. Krystal. 1995. Tyrosine 343 in the erythropoietin receptor positively regulates erythropoietin-induced cell proliferation and Stat5 activation. EMBO J. 14:5557.[Medline]
16. Gobert, S., S. Chresien, F. Gouilleux, O. Muller, C. Pallad, I. Dusanter-Fourt, B. Groner, C. Lacombe, S. Gisselbrecht, P. Mayeux. 1996. Identification of tyrosine residues within the intracellular domain of the erythropoietin receptor crucial for STAT5 activation. EMBO J. 15:2434.[Medline]
17. Mui, A. L., H. Wakao, T. Kinoshita, T. Kitamura, A. Miyajima. 1996. Suppression of interleukin-3-induced gene expression by a C-terminal truncated STAT5: role of STAT5 in proliferation. EMBO J. 15:2425.[Medline]
18. Nakajima, H., X. Liu, A. Wynshaw-Boris, L. A. Rosenthal, K. Imada, D. S. Finbloom, L. Hennighausen, W. J. Leonard. 1997. An indirect effect of Stat5a in IL-2-induced proliferation: a critical role for Stat5a in IL-2-mediated IL-2 receptor chain induction. Immunity 7:691.[Medline]
19. Chin, Y. E., M. Kitagawa, W. C. S. Su, Z. H. You, Y. Iwamoto, X. Y. Fu. 1996. Cell growth arrest and induction of cyclin-dependent kinase p21^WAF1/CIP1 mediated by STAT1. Science 272:719.[Abstract]
20. Kaplan, M. H., C. Daniel, U. Schindler, M. J. Grusby. 1998. Stat protein control lymphocyte proliferation by regulating p27^Kip1 expression. Mol. Cell. Biol. 18:1996.[Abstract/Free Full Text]
21. Yu, C.-L., D. J. Meyer, G. S. Campbell, A. C. Larner, C. Carter-Su, J. Scwartz, R. Jove. 1995. Enhanced DNA-binding activity of a Stat3-related protein in cells transformed by the Src oncoprotein. Science 269:81.[Abstract/Free Full Text]
22. Chaturvedi, P., S. Sharma, E. P. Reddy. 1997. Abrogation of interleukin-3 dependence of myeloid cells by the v-src oncogene requires SH2 and SH3 domains which specify activation of STATs. Mol. Cell. Biol. 17:3295.[Abstract]
23. Akira, S., Y. Nishio, M. Inoue, X. Wang, S. Wei, T. Matsusaka, K. Yoshida, T. Sudo, M. Naruto, T. Kishimoto. 1994. Molecular cloning of APRF, a novel IFN-stimulated gene factor 3 p91-related transcription factor involved in the gp130-mediated signaling pathway. Cell 77:63.[Medline]
24. Zhong, Z., Z. Wen, Jr J. E. Darnell. 1994. Stat3: a STAT family member activated by tyrosine phosphorylation in response to epidermal growth factor and interleukin-6. Science 264:95.[Abstract/Free Full Text]
25. Akira, S.. 1998. IL-6-regulated transcription factors. Int. J. Biochem. Cell Biol. 29:1401.
26. Migone, T.- S., X. Lin, A. Cereseto, J. C. Mulloy, J. J. O’Shea, G. Franchini, W. J. Leonard. 1995. Constitutively activated Jak-STAT pathway in T cells transformed with HTLV-1. Science 269:79.[Abstract/Free Full Text]
27. Zhang, Q., I. Nowak, E. C. Vonderheid, A. H. Rook, M. E. Kadin, P. C. Nowell, L. M. Shaw, M. A. Wasik. 1996. Activation of Jak/STAT proteins involved in signal transduction pathway mediated by receptor for interleukin 2 in malignant T lymphocytes derived from cutaneous anaplastic large T-cell lymphoma and Sezary syndrome. Proc. Natl. Acad. Sci. USA 93:9148.[Abstract/Free Full Text]
28. Nielsen, M., K. Kaltoft, M. Nordahl, C. Ropke, C. Geisler, T. Mustelin, P. Dobson, A. Svejgaard, N. Odum. 1997. Constitutive activation of a slowly migrating isoform of Stat3 in mycosis fungoides: tyrphostin AG490 inhibits Stat3 activation and growth of mycosis fungoides tumor cell lines. Proc. Natl. Acad. Sci. USA 94:6764.[Abstract/Free Full Text]
29. Takemoto, S., J. C. Molloy, A. Cereseto, T.-S. Migone, B. K. R. Patel, M. Matsuoka, K. Yamaguchi, K. Takatsuki, S. Kamihira, J. D. White, W. J. Leonard, T. Waldmann, G. Franchini. 1997. Proliferation of adult T cell leukemia/lymphoma cells is associated with the constitutive activation of JAK/STAT proteins. Proc. Natl. Acad. Sci. USA 94:13897.[Abstract/Free Full Text]
30. Yu, C.-L., R. Jove, S. J. Burakoff. 1997. Constitutive activation of the Janus kinase-STAT pathway in T lymphoma overexpressing the Lck protein tyrosine kinase. J. Immunol. 159:5206.[Abstract]
31. Takeda, K., K. Noguchi, W. Shi, T. Tanaka, M. Matsumoto, N. Yoshida, T. Kishimoto, S. Akira. 1997. Targeted disruption of the mouse Stat3 gene leads to early embryonic lethality. Proc. Natl. Acad. Sci. USA 94:3801.[Abstract/Free Full Text]
32. Gu, H., Y. Zou, K. Rajewsky. 1993. Independent control of immunoglobulin switch recombination at individual switch regions evidenced through Cre-loxP-mediated gene targeting. Cell 73:1155.[Medline]
33. Gu, H., J. D. Marth, P. C. Orban, H. Mossmann, K. Rajewsky. 1994. Deletion of a DNA polymerase ß gene segment in T cells using cell type-specific gene targeting. Science 265:103.[Abstract/Free Full Text]
34. Rajewsky, K., H. Gu, R. Kuhn, U. A. K. Betz, W. Muller, J. Roes, F. Schwenk. 1996. Conditional gene targeting. J. Clin. Invest. 98:600.[Medline]
35. Kaisho, T., F. Schwenk, K. Rajewsky. 1997. The roles of 1 heavy chain membrane expression and cytoplasmic tail in IgG1 responses. Science 276:412.[Abstract/Free Full Text]
36. Takahama, Y., K. Ohishi, Y. Tokoro, T. Sugawara, Y. Yoshimura, M. Okabe, T. Kinoshita, and J. Takeda. 1998. Functional competence of T cells in the absence of glycosylphosphatidylinositol-anchored proteins caused by T cell-specific disruption of the Pig-a gene. Eur. J. Immunol. In press.
37. Wang, X., T. Taga, K. Yoshida, M. Saito, T. Kishimoto, H. Kikutani. 1998. gp130, the cytokine common signal transducer of interleukin-6 cytokine family, is down-regulated in T cells in vivo by interleukin-6. Blood 91:3308.[Abstract/Free Full Text]
38. Minami, M., M. Inoue, S. Wei, K. Takeda, M. Matsumoto, T. Kishimoto, S. Akira. 1996. STAT3 activation is a critical step in gp130-mediated terminal differentiation and growth arrest of a myeloid cell line. Proc. Natl. Acad. Sci. USA 93:3963.[Abstract/Free Full Text]
39. Boeuf, H., C. Hauss, F. de Grave, N. Bara, C. Kedinger. 1997. Leukemia inhibitory factor-dependent transcriptional activation in embryonic stem cells. J. Cell Biol. 138:1207.[Abstract/Free Full Text]
40. Nakayama, K., K.-I. Nakayama, I. Negishi, K. Kuida, H. Sawa, D. Y. Loh. 1994. Targeted disruption of Bcl-2ß in mice: occurrence of gray hair, polycystic kidney disease, and lymphocytopenia. Proc. Natl. Acad. Sci. USA 91:3700.[Abstract/Free Full Text]
41. Boise, L. H., M. Gonzalez-Garcia, C. E. Postema, L. Ding, T. Lindsten, L. A. Turka, X. Mao, G. Nunez, C. B. Thompson. 1993. bcl-x, a bcl-2-related gene that functions as a dominant regulator of apoptotic cell death. Cell 74:597.[Medline]
42. Motoyama, N., F. Wang, K. A. Roth, H. Sawa, K.-I. Nakayama, K. Nakayama, I. Negishi, S. Senju, Q. Zhang, S. Fujii, D. Y. Loh. 1995. Massive cell death of immature hematopoietic cells and neurons in Bcl-x-deficient mice. Science 267:1506.[Abstract/Free Full Text]
43. Takayama, S., T. Sato, S. Krajewski, K. Kochel, S. Irie, J. A. Millan, J. C. Reed. 1995. Cloning and functional analysis of BAG-1: a novel Bcl-2-binding protein with anti-cell death activity. Cell 80:279.[Medline]
44. Bernad, A., M. Kopf, R. Kulbacki, N. Weich, G. Koehler, J. C. Gutierrez-Ramos. 1994. Interleukin-6 is required in vivo for the regulation of stem cells and committed progenitors of the hematopoietic system. Immunity 1:725.[Medline]
45. Kopf, M., M. Lamers, H. Bluethman, G. Koehler. 1994. IL-6-deficient mice show immunologic abnormalities. Nature 376:339.
46. Lotz, M., F. Jirik, P. Kabouridis, C. Tsoukas, T. Hirano, T. Kishimoto, D. A. Carson. 1988. B cell stimulating factor 2/interleukin 6 is a costimulant for human thymocytes and T lymphocytes. J. Exp. Med. 167:1253.[Abstract/Free Full Text]
47. Teague, T. K., P. Marrack, J. W. Kappler, A. T. Vella. 1997. IL-6 rescues resting T cells from apoptosis. J. Immunol. 158:5791.[Abstract]
48. Gratiot-Deans, J., L. Ding, L. A. Turka, G. Nunez. 1993. Bcl-2 proto-oncogene expression during human T cell development: evidence for biphasic regulation. J. Immunol. 151:83.[Abstract]
49. Gratiot-Deans, J., R. Merino, G. Nunez, L. A. Turka. 1994. Bcl-2 expression during T-cell development: early loss and late return occur at specific stages of commitment to differentiation and survival. Proc. Natl. Acad. Sci. USA 91:10685.[Abstract/Free Full Text]
50. Nakayama, K.-I., K. Nakayama, I. Negishi, K. Kuida, Y. Shinkai, M. C. Louie, L. E. Fields, P. J. Lucas, V. Stewart, F. W. Alt, D. Y. Loh. 1993. Disappearance of the lymphoid system in Bcl-2 homozygous mutant chimeric mice. Science 261:1584.[Abstract/Free Full Text]
51. Veis, D. J., C. M. Sorenson, J. R. Shutter, S. J. Korsmeyer. 1993. Bcl-2-deficient mice demonstrate fluminant lymphoid apoptosis, polycystic kidneys, and hypopigmented hair. Cell 75:229.[Medline]
52. Akashi, K., M. Kondo, U. von Freeden-Jeffry, R. Murray, I. L. Weissman. 1997. Bcl-2 rescues T lymphopoiesis in interleukin-7 receptor-deficient mice. Cell 89:1033.[Medline]

This article has been cited by other articles:

				G. Pickert, C. Neufert, M. Leppkes, Y. Zheng, N. Wittkopf, M. Warntjen, H.-A. Lehr, S. Hirth, B. Weigmann, S. Wirtz, et al. STAT3 links IL-22 signaling in intestinal epithelial cells to mucosal wound healing J. Exp. Med., July 6, 2009; 206(7): 1465 - 1472. [Abstract] [Full Text] [PDF]

				H. Shiraishi, H. Yoshida, K. Saeki, Y. Miura, S. Watanabe, T. Ishizaki, M. Hashimoto, G. Takaesu, T. Kobayashi, and A. Yoshimura Prostaglandin E2 is a major soluble factor produced by stromal cells for preventing inflammatory cytokine production from dendritic cells Int. Immunol., September 1, 2008; 20(9): 1219 - 1229. [Abstract] [Full Text] [PDF]

				J. E. Herrmann, T. Imura, B. Song, J. Qi, Y. Ao, T. K. Nguyen, R. A. Korsak, K. Takeda, S. Akira, and M. V. Sofroniew STAT3 is a Critical Regulator of Astrogliosis and Scar Formation after Spinal Cord Injury J. Neurosci., July 9, 2008; 28(28): 7231 - 7243. [Abstract] [Full Text] [PDF]

				J. Gagnon, S. Ramanathan, C. Leblanc, A. Cloutier, P. P. McDonald, and S. Ilangumaran IL-6, in Synergy with IL-7 or IL-15, Stimulates TCR-Independent Proliferation and Functional Differentiation of CD8+ T Lymphocytes J. Immunol., June 15, 2008; 180(12): 7958 - 7968. [Abstract] [Full Text] [PDF]

				H. Kida, M. L. Mucenski, A. R. Thitoff, T. D. Le Cras, K.-S. Park, M. Ikegami, W. Muller, and J. A. Whitsett GP130-STAT3 Regulates Epithelial Cell Migration and Is Required for Repair of the Bronchiolar Epithelium Am. J. Pathol., June 1, 2008; 172(6): 1542 - 1554. [Abstract] [Full Text] [PDF]

				Y. Matsuzaki, V. Besnard, J. C. Clark, Y. Xu, S. E. Wert, M. Ikegami, and J. A. Whitsett STAT3 Regulates ABCA3 Expression and Influences Lamellar Body Formation in Alveolar Type II Cells Am. J. Respir. Cell Mol. Biol., May 1, 2008; 38(5): 551 - 558. [Abstract] [Full Text] [PDF]

				M. A. Ozog, G. Modha, J. Church, R. Reilly, and C. C. Naus Co-administration of Ciliary Neurotrophic Factor with Its Soluble Receptor Protects against Neuronal Death and Enhances Neurite Outgrowth J. Biol. Chem., March 7, 2008; 283(10): 6546 - 6560. [Abstract] [Full Text] [PDF]

				M. L. Piper, E. K. Unger, M. G. Myers Jr., and A. W. Xu Specific Physiological Roles for Signal Transducer and Activator of Transcription 3 in Leptin Receptor-Expressing Neurons Mol. Endocrinol., March 1, 2008; 22(3): 751 - 759. [Abstract] [Full Text] [PDF]

				S. Kennedy Norton, B. Barnstein, J. Brenzovich, D. P. Bailey, M. Kashyap, K. Speiran, J. Ford, D. Conrad, S. Watowich, M. R. Moralle, et al. IL-10 Suppresses Mast Cell IgE Receptor Expression and Signaling In Vitro and In Vivo J. Immunol., March 1, 2008; 180(5): 2848 - 2854. [Abstract] [Full Text] [PDF]

				T. Owaki, M. Asakawa, N. Morishima, I. Mizoguchi, F. Fukai, K. Takeda, J. Mizuguchi, and T. Yoshimoto STAT3 Is Indispensable to IL-27-Mediated Cell Proliferation but Not to IL-27-Induced Th1 Differentiation and Suppression of Proinflammatory Cytokine Production J. Immunol., March 1, 2008; 180(5): 2903 - 2911. [Abstract] [Full Text] [PDF]

				M. Huber, V. Steinwald, A. Guralnik, A. Brustle, P. Kleemann, C. Rosenplanter, T. Decker, and M. Lohoff IL-27 inhibits the development of regulatory T cells via STAT3 Int. Immunol., February 1, 2008; 20(2): 223 - 234. [Abstract] [Full Text] [PDF]

				Y.-S. Bong, H.-S. Lee, L. Carim-Todd, K. Mood, T. G. Nishanian, L. Tessarollo, and I. O. Daar ephrinB1 signals from the cell surface to the nucleus by recruitment of STAT3 PNAS, October 30, 2007; 104(44): 17305 - 17310. [Abstract] [Full Text] [PDF]

				C. Brender, G. M. Tannahill, B. J. Jenkins, J. Fletcher, R. Columbus, C. J. M. Saris, M. Ernst, N. A. Nicola, D. J. Hilton, W. S. Alexander, et al. Suppressor of cytokine signaling 3 regulates CD8 T-cell proliferation by inhibition of interleukins 6 and 27 Blood, October 1, 2007; 110(7): 2528 - 2536. [Abstract] [Full Text] [PDF]

				Y. Li, H. Du, Y. Qin, J. Roberts, O. W. Cummings, and C. Yan Activation of the Signal Transducers and Activators of the Transcription 3 Pathway in Alveolar Epithelial Cells Induces Inflammation and Adenocarcinomas in Mouse Lung Cancer Res., September 15, 2007; 67(18): 8494 - 8503. [Abstract] [Full Text] [PDF]

				W. H. Luty, D. Rodeberg, J. Parness, and Y. M. Vyas Antiparallel Segregation of Notch Components in the Immunological Synapse Directs Reciprocal Signaling in Allogeneic Th:DC Conjugates J. Immunol., July 15, 2007; 179(2): 819 - 829. [Abstract] [Full Text] [PDF]

				M. Nishihara, H. Ogura, N. Ueda, M. Tsuruoka, C. Kitabayashi, F. Tsuji, H. Aono, K. Ishihara, E. Huseby, U. A. K. Betz, et al. IL-6-gp130-STAT3 in T cells directs the development of IL-17+ Th with a minimum effect on that of Treg in the steady state Int. Immunol., June 1, 2007; 19(6): 695 - 702. [Abstract] [Full Text] [PDF]

				S. Finotto, T. Eigenbrod, R. Karwot, I. Boross, A. Doganci, H. Ito, N. Nishimoto, K. Yoshizaki, T. Kishimoto, S. Rose-John, et al. Local blockade of IL-6R signaling induces lung CD4+ T cell apoptosis in a murine model of asthma via regulatory T cells Int. Immunol., June 1, 2007; 19(6): 685 - 693. [Abstract] [Full Text] [PDF]

				M. C. Simeone-Penney, M. Severgnini, P. Tu, R. J. Homer, T. J. Mariani, L. Cohn, and A. R. Simon Airway Epithelial STAT3 Is Required for Allergic Inflammation in a Murine Model of Asthma J. Immunol., May 15, 2007; 178(10): 6191 - 6199. [Abstract] [Full Text] [PDF]

				R. Zeng, R. Spolski, E. Casas, W. Zhu, D. E. Levy, and W. J. Leonard The molecular basis of IL-21-mediated proliferation Blood, May 15, 2007; 109(10): 4135 - 4142. [Abstract] [Full Text] [PDF]

				M. Zhou, L. McPherson, D. Feng, A. Song, C. Dong, S.-C. Lyu, L. Zhou, X. Shi, Y.-T. Ahn, D. Wang, et al. Kruppel-Like Transcription Factor 13 Regulates T Lymphocyte Survival In Vivo J. Immunol., May 1, 2007; 178(9): 5496 - 5504. [Abstract] [Full Text] [PDF]

				A. N. Mathur, H.-C. Chang, D. G. Zisoulis, G. L. Stritesky, Q. Yu, J. T. O'Malley, R. Kapur, D. E. Levy, G. S. Kansas, and M. H. Kaplan Stat3 and Stat4 Direct Development of IL-17-Secreting Th Cells J. Immunol., April 15, 2007; 178(8): 4901 - 4907. [Abstract] [Full Text] [PDF]

				X. O. Yang, A. D. Panopoulos, R. Nurieva, S. H. Chang, D. Wang, S. S. Watowich, and C. Dong STAT3 Regulates Cytokine-mediated Generation of Inflammatory Helper T Cells J. Biol. Chem., March 30, 2007; 282(13): 9358 - 9363. [Abstract] [Full Text] [PDF]

				D. Cao, T. L. Tal, L. M. Graves, I. Gilmour, W. Linak, W. Reed, P. A. Bromberg, and J. M. Samet Diesel exhaust particulate-induced activation of Stat3 requires activities of EGFR and Src in airway epithelial cells Am J Physiol Lung Cell Mol Physiol, February 1, 2007; 292(2): L422 - L429. [Abstract] [Full Text] [PDF]

				A. W. Xu, L. Ste-Marie, C. B. Kaelin, and G. S. Barsh Inactivation of Signal Transducer and Activator of Transcription 3 in Proopiomelanocortin (Pomc) Neurons Causes Decreased Pomc Expression, Mild Obesity, and Defects in Compensatory Refeeding Endocrinology, January 1, 2007; 148(1): 72 - 80. [Abstract] [Full Text] [PDF]

				A. D. Panopoulos, L. Zhang, J. W. Snow, D. M. Jones, A. M. Smith, K. C. El Kasmi, F. Liu, M. A. Goldsmith, D. C. Link, P. J. Murray, et al. STAT3 governs distinct pathways in emergency granulopoiesis and mature neutrophils Blood, December 1, 2006; 108(12): 3682 - 3690. [Abstract] [Full Text] [PDF]

				Z. S. Nagy, H. Rui, S. M. Stepkowski, J. Karras, and R. A. Kirken A Preferential Role for STAT5, not Constitutively Active STAT3, in Promoting Survival of a Human Lymphoid Tumor J. Immunol., October 15, 2006; 177(8): 5032 - 5040. [Abstract] [Full Text] [PDF]

				T. Yoshimura, A. Takeda, S. Hamano, Y. Miyazaki, I. Kinjyo, T. Ishibashi, A. Yoshimura, and H. Yoshida Two-Sided Roles of IL-27: Induction of Th1 Differentiation on Naive CD4+ T Cells versus Suppression of Proinflammatory Cytokine Production Including IL-23-Induced IL-17 on Activated CD4+ T Cells Partially Through STAT3-Dependent Mechanism J. Immunol., October 15, 2006; 177(8): 5377 - 5385. [Abstract] [Full Text] [PDF]

				C. B. Kaelin, L. Gong, A. W. Xu, F. Yao, K. Hockman, G. J. Morton, M. W. Schwartz, G. S. Barsh, and R. G. MacKenzie Signal Transducer and Activator of Transcription (Stat) Binding Sites But Not Stat3 Are Required for Fasting-Induced Transcription of Agouti-Related Protein Messenger Ribonucleic Acid Mol. Endocrinol., October 1, 2006; 20(10): 2591 - 2602. [Abstract] [Full Text] [PDF]

				Y. Matsuzaki, Y. Xu, M. Ikegami, V. Besnard, K.-S. Park, W. M. Hull, S. E. Wert, and J. A. Whitsett Stat3 Is Required for Cytoprotection of the Respiratory Epithelium during Adenoviral Infection J. Immunol., July 1, 2006; 177(1): 527 - 537. [Abstract] [Full Text] [PDF]

				T. Yoshimatsu, D. Kawaguchi, K. Oishi, K. Takeda, S. Akira, N. Masuyama, and Y. Gotoh Non-cell-autonomous action of STAT3 in maintenance of neural precursor cells in the mouse neocortex Development, July 1, 2006; 133(13): 2553 - 2563. [Abstract] [Full Text] [PDF]

				T. Miyatsuka, H. Kaneto, T. Shiraiwa, T.-a. Matsuoka, K. Yamamoto, K. Kato, Y. Nakamura, S. Akira, K. Takeda, Y. Kajimoto, et al. Persistent expression of PDX-1 in the pancreas causes acinar-to-ductal metaplasia through Stat3 activation Genes & Dev., June 1, 2006; 20(11): 1435 - 1440. [Abstract] [Full Text] [PDF]

				A. Tedgui and Z. Mallat Cytokines in Atherosclerosis: Pathogenic and Regulatory Pathways Physiol Rev, April 1, 2006; 86(2): 515 - 581. [Abstract] [Full Text] [PDF]

				T. Owaki, M. Asakawa, S. Kamiya, K. Takeda, F. Fukai, J. Mizuguchi, and T. Yoshimoto IL-27 Suppresses CD28-Medicated IL-2 Production through Suppressor of Cytokine Signaling 3. J. Immunol., March 1, 2006; 176(5): 2773 - 2780. [Abstract] [Full Text] [PDF]

				M. Gartsbein, A. Alt, K. Hashimoto, K. Nakajima, T. Kuroki, and T. Tennenbaum The role of protein kinase C {delta} activation and STAT3 Ser727 phosphorylation in insulin-induced keratinocyte proliferation J. Cell Sci., February 1, 2006; 119(3): 470 - 481. [Abstract] [Full Text] [PDF]

				J. L. Fornek, L. T. Tygrett, T. J. Waldschmidt, V. Poli, R. C. Rickert, and G. S. Kansas Critical role for Stat3 in T-dependent terminal differentiation of IgG B cells Blood, February 1, 2006; 107(3): 1085 - 1091. [Abstract] [Full Text] [PDF]

				A. V. Villarino, J. S. Stumhofer, C. J. M. Saris, R. A. Kastelein, F. J. de Sauvage, and C. A. Hunter IL-27 Limits IL-2 Production during Th1 Differentiation J. Immunol., January 1, 2006; 176(1): 237 - 247. [Abstract] [Full Text] [PDF]

				H. Mechoulam and E. A. Pierce Expression and Activation of STAT3 in Ischemia-Induced Retinopathy Invest. Ophthalmol. Vis. Sci., December 1, 2005; 46(12): 4409 - 4416. [Abstract] [Full Text] [PDF]

				M. Ikegami, J. A. Whitsett, P. C. Martis, and T. E. Weaver Reversibility of lung inflammation caused by SP-B deficiency Am J Physiol Lung Cell Mol Physiol, December 1, 2005; 289(6): L962 - L970. [Abstract] [Full Text] [PDF]

				V. Selvaraj, D. Bunick, C. Finnigan-Bunick, R. W. Johnson, H. Wang, L. Liu, and P. S. Cooke Gene Expression Profiling of 17{beta}-Estradiol and Genistein Effects on Mouse Thymus Toxicol. Sci., September 1, 2005; 87(1): 97 - 112. [Abstract] [Full Text] [PDF]

				Y. Kato, A. Iwama, Y. Tadokoro, K. Shimoda, M. Minoguchi, S. Akira, M. Tanaka, A. Miyajima, T. Kitamura, and H. Nakauchi Selective activation of STAT5 unveils its role in stem cell self-renewal in normal and leukemic hematopoiesis J. Exp. Med., July 5, 2005; 202(1): 169 - 179. [Abstract] [Full Text] [PDF]

				R. M. McLoughlin, B. J. Jenkins, D. Grail, A. S. Williams, C. A. Fielding, C. R. Parker, M. Ernst, N. Topley, and S. A. Jones IL-6 trans-signaling via STAT3 directs T cell infiltration in acute inflammation PNAS, July 5, 2005; 102(27): 9589 - 9594. [Abstract] [Full Text] [PDF]

				B. J. Jenkins, A. W. Roberts, M. Najdovska, D. Grail, and M. Ernst The threshold of gp130-dependent STAT3 signaling is critical for normal regulation of hematopoiesis Blood, May 1, 2005; 105(9): 3512 - 3520. [Abstract] [Full Text] [PDF]

				G. Matarese, S. Moschos, and C. S. Mantzoros Leptin in Immunology J. Immunol., March 15, 2005; 174(6): 3137 - 3142. [Abstract] [Full Text] [PDF]

				B. A. Butcher, L. Kim, A. D. Panopoulos, S. S. Watowich, P. J. Murray, and E. Y. Denkers Cutting Edge: IL-10-Independent STAT3 Activation by Toxoplasma gondii Mediates Suppression of IL-12 and TNF-{alpha} in Host Macrophages J. Immunol., March 15, 2005; 174(6): 3148 - 3152. [Abstract] [Full Text] [PDF]

				Y. Yang, J. Ochando, A. Yopp, J. S. Bromberg, and Y. Ding IL-6 Plays a Unique Role in Initiating c-Maf Expression during Early Stage of CD4 T Cell Activation J. Immunol., March 1, 2005; 174(5): 2720 - 2729. [Abstract] [Full Text] [PDF]

				B. Ahr, M. Denizot, V. Robert-Hebmann, A. Brelot, and M. Biard-Piechaczyk Identification of the Cytoplasmic Domains of CXCR4 Involved in Jak2 and STAT3 Phosphorylation J. Biol. Chem., February 25, 2005; 280(8): 6692 - 6700. [Abstract] [Full Text] [PDF]

				N. Schick, E. J. Oakeley, N. E. Hynes, and A. Badache TEL/ETV6 Is a Signal Transducer and Activator of Transcription 3 (Stat3)-induced Repressor of Stat3 Activity J. Biol. Chem., September 10, 2004; 279(37): 38787 - 38796. [Abstract] [Full Text] [PDF]

				R. M. Smith, N. Suleman, L. Lacerda, L. H. Opie, S. Akira, K. R. Chien, and M. N. Sack Genetic depletion of cardiac myocyte STAT-3 abolishes classical preconditioning Cardiovasc Res, September 1, 2004; 63(4): 611 - 616. [Abstract] [Full Text] [PDF]

				R. Sun, Z. Tian, S. Kulkarni, and B. Gao IL-6 Prevents T Cell-Mediated Hepatitis via Inhibition of NKT Cells in CD4+ T Cell- and STAT3-Dependent Manners J. Immunol., May 1, 2004; 172(9): 5648 - 5655. [Abstract] [Full Text] [PDF]

				K. Schroder, P. J. Hertzog, T. Ravasi, and D. A. Hume Interferon-{gamma}: an overview of signals, mechanisms and functions J. Leukoc. Biol., February 1, 2004; 75(2): 163 - 189. [Abstract] [Full Text] [PDF]

				Y. Cui, L. Huang, F. Elefteriou, G. Yang, J. M. Shelton, J. E. Giles, O. K. Oz, T. Pourbahrami, C. Y. H. Lu, J. A. Richardson, et al. Essential Role of STAT3 in Body Weight and Glucose Homeostasis Mol. Cell. Biol., January 1, 2004; 24(1): 258 - 269. [Abstract] [Full Text] [PDF]

				Y. Shen, K. Schlessinger, X. Zhu, E. Meffre, F. Quimby, D. E. Levy, and J. E. Darnell Jr. Essential Role of STAT3 in Postnatal Survival and Growth Revealed by Mice Lacking STAT3 Serine 727 Phosphorylation Mol. Cell. Biol., January 1, 2004; 24(1): 407 - 419. [Abstract] [Full Text] [PDF]

				A. Kano, M. J. Wolfgang, Q. Gao, J. Jacoby, G.-X. Chai, W. Hansen, Y. Iwamoto, J. S. Pober, R. A. Flavell, and X.-Y. Fu Endothelial Cells Require STAT3 for Protection against Endotoxin-induced Inf lammation J. Exp. Med., November 17, 2003; 198(10): 1517 - 1525. [Abstract] [Full Text] [PDF]

				Z. Percario, E. Olivetta, G. Fiorucci, G. Mangino, S. Peretti, G. Romeo, E. Affabris, and M. Federico Human immunodeficiency virus type 1 (HIV-1) Nef activates STAT3 in primary human monocyte/macrophages through the release of soluble factors: involvement of Nef domains interacting with the cell endocytotic machinery J. Leukoc. Biol., November 1, 2003; 74(5): 821 - 832. [Abstract] [Full Text] [PDF]

				S. Tomita, H.-B. Jiang, T. Ueno, S. Takagi, K. Tohi, S.-i. Maekawa, A. Miyatake, A. Furukawa, F. J. Gonzalez, J. Takeda, et al. T Cell-Specific Disruption of Arylhydrocarbon Receptor Nuclear Translocator (Arnt) Gene Causes Resistance to 2,3,7,8-Tetrachlorodibenzo-p-dioxin-Induced Thymic Involution J. Immunol., October 15, 2003; 171(8): 4113 - 4120. [Abstract] [Full Text] [PDF]

				A. B. Waxman, K. Mahboubi, R. G. Knickelbein, L. L. Mantell, N. Manzo, J. S. Pober, and J. A. Elias Interleukin-11 and Interleukin-6 Protect Cultured Human Endothelial Cells from H2O2-Induced Cell Death Am. J. Respir. Cell Mol. Biol., October 1, 2003; 29(4): 513 - 522. [Abstract] [Full Text] [PDF]

				A. C. Bharti, N. Donato, and B. B. Aggarwal Curcumin (Diferuloylmethane) Inhibits Constitutive and IL-6-Inducible STAT3 Phosphorylation in Human Multiple Myeloma Cells J. Immunol., October 1, 2003; 171(7): 3863 - 3871. [Abstract] [Full Text] [PDF]

				J. M. Shillingford, K. Miyoshi, G. W. Robinson, B. Bierie, Y. Cao, M. Karin, and L. Hennighausen Proteotyping of Mammary Tissue from Transgenic and Gene Knockout Mice with Immunohistochemical Markers: a Tool To Define Developmental Lesions J. Histochem. Cytochem., May 1, 2003; 51(5): 555 - 565. [Abstract] [Full Text] [PDF]

				M. Benekli, M. R. Baer, H. Baumann, and M. Wetzler Signal transducer and activator of transcription proteins in leukemias Blood, April 15, 2003; 101(8): 2940 - 2954. [Abstract] [Full Text] [PDF]

				T. Welte, S. S. M. Zhang, T. Wang, Z. Zhang, D. G. T. Hesslein, Z. Yin, A. Kano, Y. Iwamoto, E. Li, J. E. Craft, et al. STAT3 deletion during hematopoiesis causes Crohn's disease-like pathogenesis and lethality: A critical role of STAT3 in innate immunity PNAS, February 18, 2003; 100(4): 1879 - 1884. [Abstract] [Full Text] [PDF]

				H. Sanjo, K. Takeda, T. Tsujimura, J. Ninomiya-Tsuji, K. Matsumoto, and S. Akira TAB2 Is Essential for Prevention of Apoptosis in Fetal Liver but Not for Interleukin-1 Signaling Mol. Cell. Biol., February 15, 2003; 23(4): 1231 - 1238. [Abstract] [Full Text] [PDF]

				M. Yamada, N. Ishii, H. Asao, K. Murata, C. Kanazawa, H. Sasaki, and K. Sugamura Signal-Transducing Adaptor Molecules STAM1 and STAM2 Are Required for T-Cell Development and Survival Mol. Cell. Biol., December 15, 2002; 22(24): 8648 - 8658. [Abstract] [Full Text] [PDF]

				M. J. Scott, C. J. Godshall, and W. G. Cheadle Jaks, STATs, Cytokines, and Sepsis Clin. Vaccine Immunol., November 1, 2002; 9(6): 1153 - 1159. [Full Text] [PDF]

				T. Atsumi, K. Ishihara, D. Kamimura, H. Ikushima, T. Ohtani, S. Hirota, H. Kobayashi, S.-J. Park, Y. Saeki, Y. Kitamura, et al. A Point Mutation of Tyr-759 in Interleukin 6 Family Cytokine Receptor Subunit gp130 Causes Autoimmune Arthritis J. Exp. Med., October 7, 2002; 196(7): 979 - 990. [Abstract] [Full Text] [PDF]

				R. C. Humphreys, B. Bierie, L. Zhao, R. Raz, D. Levy, and L. Hennighausen Deletion of Stat3 Blocks Mammary Gland Involution and Extends Functional Competence of the Secretory Epithelium in the Absence of Lactogenic Stimuli Endocrinology, September 1, 2002; 143(9): 3641 - 3650. [Abstract] [Full Text] [PDF]

				W. Li, X. Liang, C. Kellendonk, V. Poli, and R. Taub STAT3 Contributes to the Mitogenic Response of Hepatocytes during Liver Regeneration J. Biol. Chem., August 2, 2002; 277(32): 28411 - 28417. [Abstract] [Full Text] [PDF]

				R. Shen and M. H. Kaplan The Homeostasis But Not the Differentiation of T Cells Is Regulated by p27Kip1 J. Immunol., July 15, 2002; 169(2): 714 - 721. [Abstract] [Full Text] [PDF]

				S. Sun and B. M. Steinberg PTEN is a negative regulator of STAT3 activation in human papillomavirus-infected cells J. Gen. Virol., June 1, 2002; 83(7): 1651 - 1658. [Abstract] [Full Text] [PDF]

				K. Kirito, M. Osawa, H. Morita, R. Shimizu, M. Yamamoto, A. Oda, H. Fujita, M. Tanaka, K. Nakajima, Y. Miura, et al. A functional role of Stat3 in in vivo megakaryopoiesis Blood, May 1, 2002; 99(9): 3220 - 3227. [Abstract] [Full Text] [PDF]

				I. Vancurova, R. Wu, V. Miskolci, and S. Sun Increased p50/p50 NF-{kappa}B Activation in Human Papillomavirus Type 6- or Type 11-Induced Laryngeal Papilloma Tissue J. Virol., February 1, 2002; 76(3): 1533 - 1536. [Abstract] [Full Text] [PDF]

				M. Narimatsu, H. Maeda, S. Itoh, T. Atsumi, T. Ohtani, K. Nishida, M. Itoh, D. Kamimura, S.-J. Park, K. Mizuno, et al. Tissue-Specific Autoregulation of the stat3 Gene and Its Role in Interleukin-6-Induced Survival Signals in T Cells Mol. Cell. Biol., October 1, 2001; 21(19): 6615 - 6625. [Abstract] [Full Text] [PDF]

				Z.-Q. Ning, J. Li, and R. J. Arceci Signal transducer and activator of transcription 3 activation is required for Asp816 mutant c-Kit-mediated cytokine-independent survival and proliferation in human leukemia cells Blood, June 1, 2001; 97(11): 3559 - 3567. [Abstract] [Full Text] [PDF]

				J. Suter, I. R. Hendry, L. Ndjountche, K. Obholz, J. K. Pru, J. S. Davis, and B. R. Rueda Mediators of Interferon {{gamma}}-Initiated Signaling in Bovine Luteal Cells Biol Reprod, May 1, 2001; 64(5): 1481 - 1486. [Abstract] [Full Text]

				T. Alonzi, D. Maritano, B. Gorgoni, G. Rizzuto, C. Libert, and V. Poli Essential Role of STAT3 in the Control of the Acute-Phase Response as Revealed by Inducible Gene Activation in the Liver Mol. Cell. Biol., March 1, 2001; 21(5): 1621 - 1632. [Abstract] [Full Text]

				A. Suzuki, T. Hanada, K. Mitsuyama, T. Yoshida, S. Kamizono, T. Hoshino, M. Kubo, A. Yamashita, M. Okabe, K. Takeda, et al. Cis3/Socs3/Ssi3 Plays a Negative Regulatory Role in Stat3 Activation and Intestinal Inflammation J. Exp. Med., February 19, 2001; 193(4): 471 - 482. [Abstract] [Full Text] [PDF]

				Y. Shen, G. Devgan, J. E. Darnell Jr., and J. F. Bromberg Constitutively activated Stat3 protects fibroblasts from serum withdrawal and UV-induced apoptosis and antagonizes the proapoptotic effects of activated Stat1 PNAS, February 1, 2001; (2001) 41588198. [Abstract] [Full Text]

				J. Domen and I. L. Weissman Hematopoietic Stem Cells Need Two Signals to Prevent Apoptosis; Bcl-2 Can Provide One of These, Kitl/C-KIT Signaling the Other J. Exp. Med., December 18, 2000; 192(12): 1707 - 1718. [Abstract] [Full Text] [PDF]

				R. M. GALLUCCI, P. P. SIMEONOVA, J. M. MATHESON, C. KOMMINENI, J. L. GURIEL, T. SUGAWARA, and M. I. LUSTER Impaired cutaneous wound healing in interleukin-6-deficient and immunosuppressed mice FASEB J, December 1, 2000; 14(15): 2525 - 2531. [Abstract] [Full Text]

				A. S. K. de Hooge, F. A. J. van de Loo, O. J. Arntz, and W. B. van den Berg Involvement of IL-6, Apart from Its Role in Immunity, in Mediating a Chronic Response during Experimental Arthritis Am. J. Pathol., December 1, 2000; 157(6): 2081 - 2091. [Abstract] [Full Text] [PDF]

				S. T. Ahmed and L. B. Ivashkiv Inhibition of IL-6 and IL-10 Signaling and Stat Activation by Inflammatory and Stress Pathways J. Immunol., November 1, 2000; 165(9): 5227 - 5237. [Abstract] [Full Text] [PDF]

				G. Fantuzzi and R. Faggioni Leptin in the regulation of immunity, inflammation, and hematopoiesis J. Leukoc. Biol., October 1, 2000; 68(4): 437 - 446. [Abstract] [Full Text]

				C. Kawamura, M. Kizaki, K. Yamato, H. Uchida, Y. Fukuchi, Y. Hattori, T. Koseki, T. Nishihara, and Y. Ikeda Bone morphogenetic protein-2 induces apoptosis in human myeloma cells with modulation of STAT3 Blood, September 15, 2000; 96(6): 2005 - 2011. [Abstract] [Full Text] [PDF]

				M. Fujimoto, T. Naka, R. Nakagawa, Y. Kawazoe, Y. Morita, A. Tateishi, K. Okumura, M. Narazaki, and T. Kishimoto Defective Thymocyte Development and Perturbed Homeostasis of T cells in STAT-Induced STAT Inhibitor-1/Suppressors of Cytokine Signaling-1 Transgenic Mice J. Immunol., August 15, 2000; 165(4): 1799 - 1806. [Abstract] [Full Text] [PDF]

				S. Hess, H. Smola, U. Sandaradura de Silva, D. Hadaschik, D. Kube, S. E. Baldus, U. Flucke, and H. Pfister Loss of IL-6 Receptor Expression in Cervical Carcinoma Cells Inhibits Autocrine IL-6 Stimulation: Abrogation of Constitutive Monocyte Chemoattractant Protein-1 Production J. Immunol., August 15, 2000; 165(4): 1939 - 1948. [Abstract] [Full Text] [PDF]

				K L STREETZ, T LUEDDE, M P MANNS, and C TRAUTWEIN Interleukin 6 and liver regeneration Gut, August 1, 2000; 47(2): 309 - 312. [Full Text] [PDF]

				D. DUVAL, B. REINHARDT, C. KEDINGER, and H. BOEUF Role of suppressors of cytokine signaling (Socs) in leukemia inhibitory factor (LIF) -dependent embryonic stem cell survival FASEB J, August 1, 2000; 14(11): 1577 - 1584. [Abstract] [Full Text]

				L. Rui, D. R. Gunter, J. Herrington, and C. Carter-Su Differential Binding to and Regulation of JAK2 by the SH2 Domain and N-Terminal Region of SH2-Bbeta Mol. Cell. Biol., May 1, 2000; 20(9): 3168 - 3177. [Abstract] [Full Text]

				E. S. Park, H. Kim, J. M. Suh, S. J. Park, S. H. You, H. K. Chung, K. W. Lee, O-Y. Kwon, B. Y. Cho, Y. K. Kim, et al. Involvement of JAK/STAT (Janus Kinase/Signal Transducer and Activator of Transcription) in the Thyrotropin Signaling Pathway Mol. Endocrinol., May 1, 2000; 14(5): 662 - 670. [Abstract] [Full Text]

				H. Daino, I. Matsumura, K. Takada, J. Odajima, H. Tanaka, S. Ueda, H. Shibayama, H. Ikeda, M. Hibi, T. Machii, et al. Induction of apoptosis by extracellular ubiquitin in human hematopoietic cells: possible involvement of STAT3 degradation by proteasome pathway in interleukin 6-dependent hematopoietic cells Blood, April 15, 2000; 95(8): 2577 - 2585. [Abstract] [Full Text] [PDF]

				J. R. Grandis, S. D. Drenning, Q. Zeng, S. C. Watkins, M. F. Melhem, S. Endo, D. E. Johnson, L. Huang, Y. He, and J. D. Kim Constitutive activation of Stat3 signaling abrogates apoptosis in squamous cell carcinogenesis in vivo PNAS, April 11, 2000; 97(8): 4227 - 4232. [Abstract] [Full Text] [PDF]

				I. Kato, T. Miyazaki, T. Nakamura, and A. Kudo Inducible differentiation and apoptosis of the pre-B cell receptor-positive pre-B cell line Int. Immunol., March 1, 2000; 12(3): 325 - 334. [Abstract] [Full Text] [PDF]

				K. Suzuki, H. Nakajima, Y. Saito, T. Saito, W. J. Leonard, and I. Iwamoto Janus kinase 3 (Jak3) is essential for common cytokine receptor {gamma} chain ({gamma}c)-dependent signaling: comparative analysis of {gamma}c, Jak3, and {gamma}c and Jak3 double-deficient mice Int. Immunol., February 1, 2000; 12(2): 123 - 132. [Abstract] [Full Text] [PDF]

				M. Kieslinger, I. Woldman, R. Moriggl, J. Hofmann, J.-C. Marine, J. N. Ihle, H. Beug, and T. Decker Antiapoptotic activity of Stat5 required during terminal stages of myeloid differentiation Genes & Dev., January 15, 2000; 14(2): 232 - 244. [Abstract] [Full Text]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Takeda, K. Articles by Akira, S. Search for Related Content PubMed PubMed Citation Articles by Takeda, K. Articles by Akira, S.