| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
*
Transplantation Research,
Core Technology, and
Nervous System Research, Novartis Pharma, Basel, Switzerland; and
Novartis Research Institute, Vienna, Austria
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Taking into account the different ligands for FKBP, which have
different biological effects, we asked whether ligands for cyclophilin
other than the fungal secondary metabolite CsA might exist. Those
ligands might have different biological activities as well. Screening
of microbial broth extracts for metabolites blocking the
CsA-cyclophilin A (CypA) molecular interaction led to the discovery of
the actinomycetes strain Streptomyces A92-308110
(25), which produces a class of novel macrocyclic
compounds, named sanglifehrins (26). Sanglifehrins exhibit
a high affinity for cyclophilins and show activity in the MLR
(25). Here, we report a detailed analysis of the
biological activity of sanglifehrin A (SFA), a representative of this
novel class of immunosuppressants (see Fig. 1
), and present studies to
elucidate its mechanism of action.
|
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
CsA, N-methyl-Val-4 cyclosporin (4-Cs), SFA, FK506, rapamycin, mycophenolic acid (MPA), mycophenolate mofetil (MMF), leflunomide, and brequinar were produced at Novartis Pharma (Basel, Switzerland). Dexamethasone and azathioprine were obtained from Sigma (St. Louis, MO). The compounds were dissolved in DMSO at 10-2 to 10-3 M and stored at -20°C. Samples were diluted on the day of the experiment in assay buffer or medium. IC50 values were determined from seven 2- to 3-fold dilution steps in duplicate.
Cyclophilin and FKBP binding assays
Binding of compounds to CypA and FKBP12 was assessed in
competitive ELISA formats, which are based on the interaction of
solid-phase coupled CsA-BSA, SFA-BSA, or FK506-BSA conjugates and
biotinylated CypA or biotinylated FKBP12, respectively. The CsA-CypA
ELISA and the FK506-FKBP12 ELISA have been described previously
(27, 28). For the SFA-CypA ELISA, the SFA-BSA conjugate
was prepared as follows: A SFA derivative bearing in position 53 (see
Fig. 1
) a 18-membered linker terminated by an activated succinimide
ester was prepared in two steps. First, the C53 ketone of SFA was
reductively aminated with adipic acid dihydrazide in the presence of
sodium cyanoborohydride. The product of this reaction was then coupled
with disuccinimidyl suberate. The resulting SFA-derived coupling agent
was dissolved in dimethylformamide (3 mg/ml), and 300 µl were added
to 6 mg of BSA dissolved in phosphate buffer (50 mM, 2.7 ml) at pH 7.5,
incubated for 24 h at 4°C, and used without further
purification. The SFA-BSA conjugate (0.5 µg/ml in PBS) was
coated to ELISA plates (100 µl per well) overnight at 4°C. All
subsequent steps were performed as described (27). In
competition experiments appropriate serial dilutions of test compounds
were added together with CypA-biotin.
CypA isomerase assay
SFA was tested for its effects on the peptidyl prolyl
cis-trans isomerase activity of CypA according to
Kofron et al. (29). SFA was added to a 25-nM solution of
CypA in 50 mM HEPES, 100 mM NaCl, pH 8.0 (875 µl), in a photometer
cuvette (held at 10°C) followed by 50 µl of 
-chymotrypsin
(Serva, Heidelberg, Germany) (10 mg/ml in 1 mM HCl) and 25 µl 4 mM
N-succinyl-Ala-Ala-Pro-Phe p-nitroanilide
(Bachem, Bubendorf, Switzerland) in trifluoroethanol/470 mM lithium
chloride. The increase in absorbance at 390 nm was recorded with a Cary
1E spectrophotometer (Varian, Mulgrave, Australia). Data points
were fitted to a first-order rate law to obtain the reaction
rate.
Inosine monophosphate dehydrogenase (IMPDH) assay
IMPDH was purified from bovine thymus essentially as described by Jackson et al. (30). The enzyme activity was measured spectrophotometrically at 290 nm by following NAD+-dependent formation of xanthosine monophosphate from inosine monophosphate at 37°C according to the procedure described by Magasanik (31).
Dihydro-orotate dehydrogenase (DHODH) assay
A truncated form of human DHODH (32) was expressed in Escherichia coli and partially purified. Enzyme activity was measured spectrophotometrically at room temperature by following the reduction of 2,6,-dichlorophenolindophenol essentially as described (33).
Calcineurin phosphatase assay
The calcineurin phosphatase activity was determined by HPLC assay previously described in detail by monitoring the dephosphorylation of a 19-aa phosphopeptide, a partial sequence of the regulatory subunit of cyclic adenosine 3',5'-monophosphate-dependent protein kinase (34).
Cyclophilin binding in whole cells
Cellular uptake and binding to cytosolic binding proteins was assessed by competition with [3H]CsA as described (35).
IL-2 reporter gene assay
The assay was performed as described (35) with the
exception that the 
-galactosidase reporter gene was replaced by the
luciferase gene (36). Briefly, Jurkat transfected with a
human IL-2 promoter/luciferase reporter gene construct were stimulated
with 20 ng/ml PMA and 1 µg/ml PHA in the presence of either SFA and
CsA alone or a combination of both compounds and incubated in RPMI
1640/10% FCS for 5 h at 37°C in 5%
CO2. The level of luciferase was determined by
bioluminescence measurement. The plates were centrifuged for 10 min at
500 x g, and the supernatant was removed by flicking.
Lysis buffer containing 25 mM Tris-phosphate, pH 7.8, 2 mM DTT, 2 mM
1.2-diaminocyclohexane-N,N,N',N-tetraacetic acid,
10% (v/v) glycerol, and 1% (v/v) Triton X-100 was added (20 µl per
well). The plates were incubated at room temperature for 15 min under
constant shaking. Luciferase activity was assessed with a
bioluminescence reader (Labsystem, Helsinki, Finland) after automatic
addition of 50 µl per well luciferase reaction buffer containing 20
mM Tricine, 1.07 mM
(MgCO3)4Mg(OH)2x5H2O,
2.67 mM MgSO4, 0.1 mM EDTA, 33.3 mM DTT, 270 µM
coenzyme A, 470 µM luciferin, 530 µM ATP, pH 7.8 (all obtained from
Sigma). Lag time was 0.5 s, and total measuring time was 1 or
2 s. Low control values were light units from nonstimulated cells,
and high controls were from stimulated cells without any compound.
Mouse and human MLR
The two-way mouse MLR was performed according to standard procedures (37, 38) and has been described elsewhere (25). The human MLR was performed with human PBMC as described previously (39).
Ag-specific human T cell clone
The Ag-specific human T cell clone has been described previously (28). After stimulation with Ag and irradiated PBMC from HLA-DR matched donors for 7–8 days, cells (3 x 104 per well in 200 µl RPMI 1640 medium supplemented with 5% human AB serum) were stimulated with 10 ng/ml recombinant human IL-2 (Novartis Pharma). Proliferation was determined as described (28).
IL-2 production by Jurkat cells
Jurkat cells were stimulated with PMA and PHA as described for the IL-2 reporter gene assay. After 18 h, the IL-2 content in the supernatant was determined with the IL-2-dependent murine T cell line CTLL (40).
Cytokine production by human effector T cells
Human CD4+45RO+ T
cells were separated by FACS from PBMC stained with FITC-labeled
anti-CD4 mAb plus PE-labeled anti-CD45RO mAb (Becton Dickinson,
Basel, Switzerland) to a purity of >98% as described
(41).
CD4+45RO+ cells were primed
(104 cells/ml) for 7 days, washed, and
restimulated (2 x 105/ml) for 3 days by
plate-bound anti-CD3 mAb OKT3 (25 µg/ml coated) in the presence
of IL-2 (100 U/ml). Supernatants of restimulated cells were harvested
and analyzed for IL-4 and IFN-
by ELISA as described
(41).
LPS-induced spleen cell proliferation
Spleen cells of CBA mice (2 x 105 cells per well) in 200 µl RPMI 1640/10% FCS medium were stimulated with 50 µg/ml LPS (LPS from E. coli, serotype 0111:B4; Difco, Detroit, MI) for 2 days (42). Proliferation was determined by incubation with 1 µCi [3H]thymidine (15 Ci/mmol; Amersham, Little Chalfont, U.K.) for 5 h.
Ab production by human B cells
Human CD19+ B cells were isolated to a purity of >95% by magnetic cell sorting from PBMC as described previously (43). B cells were stimulated in triplicate for 10 days by soluble CD154 (20% supernatant) and IL-4 (100 U/ml) (43). Culture supernatants were analyzed for IgG by ELISA (44).
TNF- release from human PBMC
Mononuclear cells were isolated from human blood by
Ficoll-Hypaque density separation and incubated with serial dilutions
of compounds for 30 min before addition of IFN- (100 U/ml;
Boehringer Mannheim, Mannheim, Germany) and LPS (5 µg/ml; LPS from
E. coli, serotype 026:B6; Sigma). After a 3-h incubation in
RPMI 1640/10% FCS, TNF- present in the cell culture supernatant was
determined with a commercially available ELISA kit (Innogenetics N.V.,
Zwijndrecht, Belgium).
Proliferation of mouse bone marrow cells
Bone marrow cells from CBA mice (2.5 x 104 cells per well) were incubated for 4 days in 100 µl RPMI 1640 containing 10% FCS, 100 U/ml penicillin, 100 µg/ml streptomycin (Life Technologies, Basel, Switzerland), 50 µM 2-ME (Fluka, Buchs, Switzerland), WEHI-3-conditioned medium (7.5% v/v), and L929-conditioned medium (3% v/v) as a source of growth factors. Proliferation was assessed by [3H]thymidine incorporation as described above.
Nucleoside reversal experiments
A murine MLR was performed as described above with the exception that proliferation was assessed by MTT (45). Serial dilutions of brequinar and SFA were performed either in the absence of the presence of 50 µM uridine.
Human T cells were purified from buffy coats of normal donors by density centrifugation and negative selection with anti-HLA-DR-, anti-CD14-, anti-CD16-, and anti-CD19-coated magnetic beads (Miltenyi Biotec GmbH, Bergisch-Gladbach, Germany) according to instructions of the manufacturer. Purified T cells (5 x 104) were stimulated with 1.25 µg/ml PHA for 3 days. Serial dilutions of MMF and SFA were performed in the presence or absence of 50 µM guanosine. Proliferation was assessed by [3H]thymidine incorporation.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Binding of SFA to CypA was assessed in two different competitive
ELISA formats in which the interaction between solid-phase coated
CsA-BSA or SFA-BSA conjugates and biotinylated CypA is inhibited by SFA
free in solution. In both assays, free SFA inhibited these interactions
at significantly lower concentrations than CsA (Table I), indicating a higher affinity of SFA
for CypA. CsA has been shown to inhibit the peptidyl-prolyl
cis-trans isomerase activity of CypA (46, 47). We thus tested SFA for inhibition of the isomerase activity
of CypA in a cell-free assay; again SFA was more potent than CsA (Table I). In contrast, when the binding to cyclophilin was assessed in whole
cells, the concentration of SFA needed to displace cell-associated
radioactive CsA was 
3-fold higher than that of CsA (Table II). This suggests that the permeability
of SFA into cells is lower compared with that of CsA.
|
|
We next assessed the effect of SFA on T cells. SFA inhibited the
proliferation of alloantigen-stimulated murine and human T cells in MLR
cultures with IC50 values of 95–170 nM (Table III). CsA was 15- to 35-fold more potent
in these assays. SFA also suppressed the proliferation of a human T
cell clone stimulated with IL-2 (Table III). In contrast, CsA had no
effect on the IL-2-dependent proliferation. Rapamycin was active in
this assay with an IC50 value comparable to that
reported for the Ag-specific proliferation of this T cell clone (data
not shown; Ref. 28).
|
SFA did not affect IL-2 secretion by PMA/PHA-stimulated Jurkat
cells, whereas CsA was active at low nM concentrations (Table IV). In line with these results, SFA did
not inhibit PMA/PHA-induced IL-2 transcription as assessed with an IL-2
reporter gene assay with Jurkat cells (Fig. 2). In
contrast, low nM concentrations of CsA completely prevented IL-2
transcription. SFA dose dependently abrogated this inhibitory effect of
CsA (Fig. 2), indicating that both compounds compete for the same
binding side on cyclophilin but have different effector mechanisms. To
assess the effects on cytokine production by nontransformed human T
cells, CD4+45RO+ T cells
were primed and restimulated in vitro with anti-CD3 and IL-2. The
production of both Th1 and Th2 cytokines (IFN- and IL-4,
respectively) by these effector T cells was inhibited by SFA and CsA
with similar potency (IC50, 55–310 nM; Table IV). Taken together, these results show that SFA does not affect IL-2
production but rather inhibited IL-2-dependent proliferation and
IL-2-dependent cytokine production of human T cells.
|
|
A cyclophilin-binding, nonimmunosuppressive derivative of
cyclosporin with an altered effector domain (4-Cs; Ref.
48) was used to assess whether the activity of SFA was
dependent on binding to cyclophilin. 4-Cs potently inhibited the
binding of SFA to CypA (Table I). When SFA and 4-Cs were added to MLR
cultures the activity of SFA was not abrogated, indicating that the
activity of SFA was not dependent on cyclophilin binding (Fig. 3).
|
To get further insight into the mechanism of action, the effects
of SFA on targets of known immunosuppressants were studied. FKBP12 is
the common intracellular binding protein of FK506 and rapamycin
(5). SFA did not bind to FKBP12 as assessed with a
FK506-FKBP12 binding assay (Table V).
Furthermore, SFA did not affect the phosphatase activity of calcineurin
(Table V), the effector molecule of CsA and FK506 (7, 8, 9, 23). The immunosuppressants MPA/MMF (49) and
brequinar/leflunomide (50, 51) affect de novo purine and
pyrimidine biosynthesis by inhibition of their respective targets IMPDH
(52) and DHODH (53, 54). SFA had no effect on
the enzymatic activities of these enzymes (Table V). Furthermore,
although the inhibitory effects of brequinar on the proliferation of
murine MLR cultures and of MMF on PHA-stimulated human T cells were
fully abrogated by addition of uridine and guanosine, respectively,
these nucleosides had no effect on the activity of SFA (Fig. 4). Also, all other nucleosides did not
affect the activity of SFA (data not shown). Taken together, these data
indicate that SFA has a different mechanism of action than the well
characterized immunosuppressants CsA, FK506, MMF/MPA, brequinar, and
leflunomide.
|
|
Presently known immunosuppressants act at different time points
during the process of T cell activation and proliferation. CsA and
FK506 block early, TCR-mediated gene activation, thereby preventing
cell cycle progression from G0 to
G1 phase (17, 24). Rapamycin
inhibits later stages, namely, the G1/S
transition by blocking cell proliferation in response to growth factors
(18, 19, 20, 21). MMF and brequinar, inhibiting purine and
pyrimidine synthesis, respectively, interfere with DNA synthesis and
thus block the S phase of the cell cycle (55, 56). Effects
on individual cell cycle phases can be analyzed by delayed addition of
the compounds to MLR cultures, in which T cells pass through all the
above mentioned phases within 96 h. CsA was no longer active in
the MLR when added 48 h after initiation of the culture (Fig. 5). Its IC50 value
was 110-fold higher at this time point compared with the
IC50 value obtained when added immediately at the
beginning of the culture (i.e., "normalized
IC50 " = 110). The effect of rapamycin
decreased when added after 48 h (normalized
IC50 = 50). Brequinar was fully active when added
after 48 h and essentially inactive when added after 72 h.
MMF showed full activity at all time points and was still active when
added after 91 h just before assessment of proliferation by
[3H]thymidine incorporation. SFA showed a
profile different from all these compounds; it was still active when
added 72 h after MLR initiation, but essentially inactive when
added after 91 h (normalized IC50 =
130).
|
To further profile the in vitro activities, SFA was analyzed for
its effects on B cells, monocytes, and bone marrow cells. SFA inhibited
the proliferation of murine B cells stimulated with LPS with a potency
comparable to that of MMF (Table VI). SFA
affected the IgG production by purified human B cells stimulated with
CD154 and IL-4 only at µM concentrations, which is very potently
blocked by rapamycin (Table VI). In comparison to dexamethasone, SFA
weakly affected TNF- secretion by IFN-/LPS-stimulated
PBMC. The proliferation of murine bone marrow cells in response to
growth factors was only inhibited by SFA at µM concentrations,
whereas the nucleoside analog azathioprine, whose main metabolite
6-mercaptopurine interferes with DNA synthesis (57),
prevents proliferation of these cells at nM concentrations.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
By screening microbial fermentation extracts in a CypA-binding assay we
identified an actinomycetes strain producing several closely related
metabolites with novel structures (25, 26). The so-called
sanglifehrins bind with high affinity to several cyclophilin isoforms
(25). Several lines of evidence suggest that SFA and CsA
share the same binding side on cyclophilin. Both SFA and CsA inhibit
CsA-CypA as well as SFA-CypA interactions and both compounds inhibit
the isomerase activity of CypA (Table I). Furthermore, SFA antagonizes
the activity of CsA in an IL-2 reporter gene assay by displacing CsA
from cyclophilin (Fig. 2) similar to a cyclophilin-binding,
nonimmunosuppressive cyclosporin derivative with an altered effector
domain (48). These data suggest that, despite their
overall distinct structure, SFA and CsA may display a common
three-dimensional cyclophilin-binding domain as do FK506 and rapamycin
with respect to their FKBP-binding domain (59). Indeed,
this has been recently confirmed by the x-ray structure of the CypA/SFA
complex (J. Kallen, R. Sedrani, J.-J. Sanglier, and T. Fehr,
manuscript in preparation).
Despite the higher affinity of SFA over CsA for CypA under cell-free
conditions, SFA showed a significantly lower activity than CsA in
displacing radiolabeled CsA in a cellular binding assay (Table II). We
believe that the binding of CsA to the cells in this assay is mainly
due to its interaction with intracellular cyclophilins. A possible
explanation for the difference in SFA binding to cyclophilin in the
molecular vs the cellular assay could be a lower permeability into
cells. This might also explain the relatively low activities of SFA in
MLR when compared with CsA.
In contrast to CsA, SFA did not affect IL-2 production of activated T
cells either at the transcriptional level (IL-2 reporter gene assay;
Fig. 2) or at the level of IL-2 secretion (Table IV). SFA did not
inhibit IL-2 production by mitogen-activated T cells (Table IV) or by T
cells activated by a combination of anti-TCR and anti-CD28 Abs
(data not shown). In contrast, SFA blocked the IL-2-dependent
proliferation (Table III) and cytokine production (Table IV) of T
cells. SFA still showed activity when added 72 h after initiation
of MLR cultures (Fig. 5). The latter results indicate that SFA acts at
a later stage of the cell cycle, most likely at the
G1/S transition. Taken together, these results
suggest that SFA binds to the CsA-binding side of cyclophilin but
displays a different effector domain than CsA (like FK506 vs
rapamycin), resulting in a different mechanism of action and activity
profile.
When SFA was added to MLR cultures in combination with a
cyclophilin-binding, nonimmunosuppressive cyclosporin derivative, its
activity was not abrogated even at a 10-fold molar excess (Fig. 3). At
this molar excess the cyclosporin derivative reversed >50% of the
activity of CsA in the IL-2 reporter gene assay (48).
These observations indicate that SFA exerts its effect independent of
cyclophilin.
To characterize the mechanism of action of SFA in more detail we first
analyzed its effects on targets of well characterized
immunosuppressants. SFA did not bind to FKBP nor did it inhibit the
enzymatic activities of calcineurin, IMPDH, and DHODH (Table V), the
targets of FK506, MMF/MPA, and brequinar/leflunomide, respectively.
Furthermore, the findings that the inhibition of the proliferation of
activated T cells by SFA could not be reversed by addition of exogenous
nucleosides (Fig. 4) indicates that SFA has no effects on targets
involved in the de novo nucleoside synthesis.
SFA also showed effects on other cell types. It inhibited the
proliferation of mitogen-activated B cells (Table VI). However, it had
no effect on Ab production induced by CD154 and IL-4, which, in
contrast, is blocked by rapamycin. The differential effects of SFA and
rapamycin in this assay indicate that mTOR might not be involved in the
mechanism of action of SFA. Unlike dexamethasone, SFA only weakly
inhibited TNF- production by IFN-/LPS-stimulated PBMC. SFA exerts
no general cytotoxic activity because it did not affect the
proliferation of bone marrow cells (Table VI).
In conclusion, the data presented here indicate that SFA represents a new immunosuppressive compound whose mode of action is different from that of known immunosuppressants. However, the precise mechanism of action and in particular the effector protein of SFA remains to be identified.
Note added in proof.
L.-H. Zhang and J. O. Liu recently showed that SFA inhibits IL-2-dependent T cell proliferation at the G1 phase of the cell cycle (60).
|
Acknowledgments |
|---|
|
Footnotes |
|---|
2 Abbreviations used in this paper: CsA, cyclosporin A; CypA, cyclophilin A; DHODH, dihydro-orotate dehydrogenase; FKBP, FK506 binding protein; IMPDH, inosine monophosphate dehydrogenase; MMF, mycophenolate mofetil; MPA, mycophenolic acid; mTOR, mammalian target of rapamycin; SFA, sanglifehrin A; 4-Cs, N-methyl-Val-4 cyclosporin.
Received for publication August 9, 2000. Accepted for publication April 5, 2001.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
, but no IL-4, and help efficient IgE production by B cells. J. Immunol. 154:3078.[Abstract]
This article has been cited by other articles:
|
|
 |
|
  J.-P. Evenou, J. Wagner, G. Zenke, V. Brinkmann, K. Wagner, J. Kovarik, K. A. Welzenbach, G. Weitz-Schmidt, C. Guntermann, H. Towbin, et al. The Potent Protein Kinase C-Selective Inhibitor AEB071 (Sotrastaurin) Represents a New Class of Immunosuppressive Agents Affecting Early T-Cell Activation J. Pharmacol. Exp. Ther., September 1, 2009; 330(3): 792 - 801. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Pan, C. Luo, R. Li, A. Qiao, L. Zhang, M. Mines, A. M. Nyanda, J. Zhang, and G.-H. Fan Cyclophilin A Is Required for CXCR4-mediated Nuclear Export of Heterogeneous Nuclear Ribonucleoprotein A2, Activation and Nuclear Translocation of ERK1/2, and Chemotactic Cell Migration J. Biol. Chem., January 4, 2008; 283(1): 623 - 637. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Zollinger, F. Waldmeier, S. Hartmann, G. Zenke, A. G. Zimmerlin, U. Glaenzel, J.-P. Baldeck, A. Schweitzer, S. Berthier, T. Moenius, et al. PIMECROLIMUS: ABSORPTION, DISTRIBUTION, METABOLISM, AND EXCRETION IN HEALTHY VOLUNTEERS AFTER A SINGLE ORAL DOSE AND SUPPLEMENTARY INVESTIGATIONS IN VITRO Drug Metab. Dispos., May 1, 2006; 34(5): 765 - 774. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Kallen, R. Sedrani, G. Zenke, and J. Wagner Structure of Human Cyclophilin A in Complex with the Novel Immunosuppressant Sanglifehrin A at 1.6 A Resolution J. Biol. Chem., June 10, 2005; 280(23): 21965 - 21971. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Zhang, F. Erdmann, R. Baumgrass, M. Schutkowski, and G. Fischer Unexpected Side Chain Effects at Residue 8 of Cyclosporin A Derivatives Allow Photoswitching of Immunosuppression J. Biol. Chem., February 11, 2005; 280(6): 4842 - 4850. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Sokolskaja, D. M. Sayah, and J. Luban Target Cell Cyclophilin A Modulates Human Immunodeficiency Virus Type 1 Infectivity J. Virol., December 1, 2004; 78(23): 12800 - 12808. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. M. Woltman, N. Schlagwein, S. W. van der Kooij, and C. van Kooten The Novel Cyclophilin-Binding Drug Sanglifehrin A Specifically Affects Antigen Uptake Receptor Expression and Endocytic Capacity of Human Dendritic Cells J. Immunol., May 15, 2004; 172(10): 6482 - 6489. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Allen, Y. Zheng, L. Gardner, M. Safford, M. R. Horton, and J. D. Powell The Novel Cyclophilin Binding Compound, Sanglifehrin A, Disassociates G1 Cell Cycle Arrest from Tolerance Induction J. Immunol., April 15, 2004; 172(8): 4797 - 4803. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Baumgrass, Y. Zhang, F. Erdmann, A. Thiel, M. Weiwad, A. Radbruch, and G. Fischer Substitution in Position 3 of Cyclosporin A Abolishes the Cyclophilin-mediated Gain-of-function Mechanism but Not Immunosuppression J. Biol. Chem., January 23, 2004; 279(4): 2470 - 2479. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Boulay, S. Zumstein-Mecker, C. Stephan, I. Beuvink, F. Zilbermann, R. Haller, S. Tobler, C. Heusser, T. O'Reilly, B. Stolz, et al. Antitumor Efficacy of Intermittent Treatment Schedules with the Rapamycin Derivative RAD001 Correlates with Prolonged Inactivation of Ribosomal Protein S6 Kinase 1 in Peripheral Blood Mononuclear Cells Cancer Res., January 1, 2004; 64(1): 252 - 261. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Zander, M. P. Sherman, U. Tessmer, K. Bruns, V. Wray, A. T. Prechtel, E. Schubert, P. Henklein, J. Luban, J. Neidleman, et al. Cyclophilin A Interacts with HIV-1 Vpr and Is Required for Its Functional Expression J. Biol. Chem., October 31, 2003; 278(44): 43202 - 43213. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Steinschulte, T. Taner, A. W. Thomson, G. Bein, and H. Hackstein Cutting Edge: Sanglifehrin A, a Novel Cyclophilin-Binding Immunosuppressant Blocks Bioactive IL-12 Production by Human Dendritic Cells J. Immunol., July 15, 2003; 171(2): 542 - 546. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. J. Clarke, G. P. McStay, and A. P. Halestrap Sanglifehrin A Acts as a Potent Inhibitor of the Mitochondrial Permeability Transition and Reperfusion Injury of the Heart by Binding to Cyclophilin-D at a Different Site from Cyclosporin A J. Biol. Chem., September 13, 2002; 277(38): 34793 - 34799. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Pahl, M. Zhang, K. Torok, H. Kuss, U. Friedrich, Z. Magyar, J. Szekely, K. Horvath, K. Brune, and I. Szelenyi Anti-Inflammatory Effects of a Cyclosporine Receptor-Binding Compound, D-43787 J. Pharmacol. Exp. Ther., May 1, 2002; 301(2): 738 - 746. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L.-H. Zhang, H.-D. Youn, and J. O. Liu Inhibition of Cell Cycle Progression by the Novel Cyclophilin Ligand Sanglifehrin A Is Mediated through the NFkappa B-dependent Activation of p53 J. Biol. Chem., November 16, 2001; 276(47): 43534 - 43540. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
