| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Departments of
*
Pathology and
Neurology and
Division of Rheumatology and Clinical Immunology, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
-dependent
manner. The mitochondrial pathway of oligodendrocyte apoptosis is,
therefore, inhibited by C5b-9 through post-translational regulation of
Bad. This mechanism may be involved in the promotion of oligodendrocyte
survival in inflammatory demyelinating disorders affecting the
CNS. |
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
, nerve growth factor, and the interaction of
CD95 and CD95 ligand in vivo and in vitro (8, 9, 10, 11). Some
OLG in multiple sclerosis (MS) lesions express Bcl-2, and the level of
expression correlates with the extent of remyelination (12, 13). This finding suggests that OLG are capable of antiapoptotic
response in vivo. Therefore, factors that rescue OLG from apoptosis may
increase the survival and remyelinating potential of OLG.
Complement activation with assembly of the terminal complement complex
consisting of C5b, C6, C7, C8, and C9 proteins (C5b-9) plays a
significant role in the pathogenesis of a variety of CNS diseases,
including MS, Guillain-Barré syndrome, Alzheimer’s disease,
Parkinson’s disease, and stroke (14, 15, 16, 17, 18, 19, 20). By forming
pores in the cell membrane, C5b-9 causes cell death in part through
unregulated Ca2+ influx (21, 22).
However, OLG, like other nucleated cells, survive limited complement
attack through protection by complement-inhibitory proteins and by
elimination of membranes carrying C5b-9 complexes
(23, 24, 25, 26, 27, 28). We recently demonstrated that sublytic doses of
C5b-9 inhibit the caspase-3-dependent OLG apoptosis induced in vitro by
serum deprivation or TNF- (29). The mechanisms and
signaling pathways involved in this protective activity of C5b-9 are
currently unknown. Sublytic C5b-9 induces Gi-dependent and
G
-mediated activation of Ras, proto oncogene
serine/threonine-protein kinase (Raf)-1, mitogen-activated protein
kinase-1/extracellular signal-regulated kinase-1 (MEK1), and
extracellular signal-regulated kinase-1 (ERK1) in a JY B cell line,
primary human aortic smooth muscle cells, and primary rat OLG
(30, 31, 32, 33). Phosphatidylinositol 3-phosphate kinase
(PI-3K) signaling appears to be required for cell survival
(34) including OLG and OLG progenitor cells (OPC)
(35). Thus, the recent finding that PI-3K is activated by
C5b-9 in aortic smooth muscle cells (33) may be
significant in C5b-9-mediated protection from apoptosis.
Both mitogen-activated protein kinase and PI-3K pathways provide survival signaling that may neutralize proapoptotic Bcl-2 proteins (36). ERK induces Bax/Bcl-2 heterodimerization by directly phosphorylating Bcl-2 and regulates Bad/Bcl-xL assembly by phosphorylating Bad through ribosomal protein 5b kinase 1 (RSK)1 (37, 38). Regulation of apoptosis by PI-3K is primarily mediated through Akt, a serine-threonine kinase, which in turn regulates Bad and caspase-9 (39, 40). BCL2-antagonist of cell death (Bad) is a cytoplasmic protein that promotes apoptosis by dimerization with Bcl-2 or Bcl-xL (39, 41). Heterodimerization of Bad with Bcl-2 or Bcl-xL reduces the number of Bcl-2 and Bcl-xL that bind to Bax or Bak, thus inhibiting the antiapoptotic activity of Bcl-2 and Bcl-xL (42, 43). Phosphorylation of Bad enhances cell survival by inducing cytoplasmic sequestration of Bad through formation of the Bad/14-3-3 protein complex (42, 43).
In this report, we demonstrate that the decrease in PI-3K and Akt activities of OLG and OPC in response to serum growth factor withdrawal is associated with an induction of apoptosis through the mitochondrial pathway. Sublytic C5b-9 assembly protected OLG from apoptosis, and this rescue was mediated by Gi-dependent activation of PI-3K/Akt. This signaling pathway appears responsible for phosphorylation of Bad at Ser112 and Ser136 and the dissociation of Bad from Bcl-xL. These findings suggest that sublytic C5b-9, a ubiquitously activated inflammatory mediator, may play a significant role in OLG survival in inflammatory CNS disorders.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Primary OPC were prepared according to the method of Saneto and DeVellis (44). Briefly, glial cells isolated from neonatal Sprague Dawley rat brains were grown for 10 days as stratified mixed cultures. OPC, obtained by shaking, were differentiated in defined medium containing serum-free DMEM-Ham’s F-12, transferrin (500 ng/ml; Sigma, St. Louis, MO), insulin (75 ng/ml; Sigma), basic fibroblast growth factor (75 µg/ml; Collaborative Research, Lexington, MA), and 1 mM sodium pyruvate. We have previously shown that after 56 h in defined medium, >85% of cells are mature OLG expressing myelin basic protein, proteolipid protein, and galactocerebroside (31). Less than 3% of cells negative for myelin basic protein are astrocytes, whereas the remaining cells stain with A2B5 Ab and are therefore progenitors in varying stages of differentiation (31). Thus, OPC cultured in defined medium for 56–72 h are designated as OLG.
Membrane assembly of sublytic C5b-9 using terminal complement proteins
In this study, sublytic C5b-9 was assembled using purified human complement proteins C5–C9 obtained from Quidel (San Diego, CA). The C5b6 complex was prepared from C5 and C6 as described (45) or purchased (Advanced Research Technologies, San Diego, CA). Cell monolayers at 106/24-cm2 flask were treated with 30 µg C5b-6 or 18 U C5b-6 (Advanced Research Technologies) for 15 min, then with C7 (10 µg) for 5 min at room temperature. C8 (10 µg) and C9 (15 µg) were added in a final volume of 1 ml, as described (21, 29, 32). Cells were incubated at 37°C for the indicated periods. The concentrations of complement proteins used in this study are sublytic for OLG, as determined by staining cells with vital dye trypan blue.
Cell death by MTS assay
Live cells were quantitated using CellTiter96Aqueous cell proliferation assay (Promega, Madison, WI), as previously described (29). In brief, OPC plated in 96-well plates at 105 cells/well in 200 µl defined medium were cultured for 56 h. After exposure of cells to C5b-9, methyltetrazolium salt (40 µl) was added at the indicated time points. The plates were incubated 2 h at 37°C, and OD was measured at 540 nm. Results are expressed as mean percent surviving cells ± SE using the initial cell number at the beginning of the experiment as 100%. Each sample was assayed in triplicate. The Student t test was used to determine the statistical significance of the results.
PI-3K and Akt kinase activity assays
PI-3K assay was performed as previously described
(33). In brief, cells were lysed in 30 mM Tris-HCl (pH
7.4), 0.15 M NaCl, 1% Nonidet P-40, 0.1% SDS, 0.5% sodium
deoxycholate, 1 mM EDTA, 1 mM DTT, 2 mM MgCl2, 1
mM NaVO4, 0.5 mM PMSF, 100 µg/ml aprotinin, and
leupeptin (RIPA buffer). Equal amounts of cell lysates (150 µg
protein) were immunoprecipitated overnight with anti-p85 PI-3K
polyclonal IgG (Santa Cruz Biotechnology, Santa Cruz, CA) in the
presence of protein A/G agarose (Calbiochem, La Jolla, CA). The beads
were washed in RIPA buffer and then with kinase buffer (20 mM Tris-HCl
(pH 7.5), 100 mM EDTA, 0.5 mM EGTA, 1 µM ATP, 10 mM
MgCl2). The immunoprecipitates were incubated
with phosphatidylinositol and 10 µCi
[-32P]ATP (NEN, Boston, MA) for 30 min at
37°C in kinase buffer. The reaction was terminated by adding 4 M HCl
and chloroform-methanol (1:1), and samples were analyzed on TLC by
allowing migration of the phosphorylated substrates. The spots were
excised, and the radioactivity was counted. For Akt assay, equal
amounts of lysates (150 µg) were subjected to immunoprecipitation
with rabbit IgG to human Akt1 (Santa Cruz Biotechnology) and protein A-
and G-agarose, as described for PI-3K. Agarose beads were washed with
RIPA buffer as above, and beads carrying the immunoprecipitates were
incubated for 10 min at 37°C in kinase buffer containing 40 µM
protein kinase A inhibitor peptide (Upstate Biotechnology, Lake Placid,
NY) and 10 µl Akt substrate peptide RPRAATF (Upstate Biotechnology;
Ref. 46). Peptide phosphorylation was assessed by loading
samples on P81 phosphocellulose paper and counting the
radioactivity.
Determination of cytochrome c (cyto-c) release
Cytoplasmic translocation of cyto-c from the mitochondrial intermembrane space was determined by digitonin permeabilization (47, 48, 49). Briefly, cells were lifted from plates by trypsinization and washed with ice-cold PBS and then with 0.25 mM EGTA. Cells were resuspended in a 20 mM HEPES buffer, pH 7.0, containing 125 mM KCl, 2 mM K2HPO4, 5 mM malate, 5 mM glutamate, and protease inhibitors. Cells were treated with 0.01% digitonin for 10 min on ice, a condition that permeabilizes >95% of cells. Permeabilized cells were centrifuged at 10,000 x g for 30 min at 4°C, and the supernatant containing cytoplasmic proteins was recovered and stored at -70°C. The pellets containing mitochondria were lysed in RIPA buffer. The protein concentration was measured by the bicinchoninic acid method (Pierce, Rockford, IL). The presence of cyto-c in the supernatant is not due to mitochondrial damage by digitonin, as shown by the release of cytoplasmic lactate dehydrogenase but not mitochondrial succinyl dehydrogenase (47). The supernatant and pellet fractions were analyzed for cyto-c by SDS-PAGE and immunoblotting with a mouse monoclonal anti-cyto-c IgG (PharMingen, San Diego, CA). Blots were also probed for actin and a mitochondrial membrane protein cyto-c oxidase subunit IV (cox IV) using antiactin IgG (Santa Cruz Biotechnology) and anti-cox IV IgG (Molecular Probes, Eugene, OR), respectively. Actin served as control for supernatant, and cox IV was used as a pellet control. The immunoreactive bands were detected using peroxidase-conjugated secondary Ab and then enhanced chemiluminescence (Pierce). The radiographic band density was measured using UN-SCAN-IT software (Silk Scientific, Orem, UT), and results are shown as density ratios to actin or cox IV.
The level of cyto-c released from the permeabilized cell cytosol was also determined by ELISA using the cyto-c immunoassay kit (R&D Systems, Minneapolis, MN). Equal amounts of protein were assayed for cyto-c, as described in the manufacturer’s instructions. Results are expressed as picograms cyto-c per microgram total supernatant protein.
Analysis of caspase-9 activation by Western blot
After exposure to C5b-9 or C5b6, cells were cultured for 18 h in defined medium and then lysed in RIPA buffer. Lysates were examined for caspase-9 cleavage products by immunoblotting using an Ab specific for the 37- and 17-kDa caspase-9 fragments (NEB, Beverly, MA).
Analysis of Akt and Bad phosphorylation
Phosphorylation of Akt and Bad was examined using NEB assay.
After exposure to C5b-9 or C5b6 for the indicated time periods, cell
lysates were immunoprecipitated with goat anti-Akt1 IgG (Santa Cruz
Biotechnology), rabbit anti-Bad IgG, rabbit IgG to
Ser112 phosphorylated Bad (NEB), and goat
anti-actin IgG together with protein A/G agarose. The beads were
washed with lysis buffer and then boiled in Laemmli sample buffer.
Eluted protein was then examined by SDS-PAGE (7.5% for Akt and 12%
for Bad) and immunoblotted using Ab to phosphorylated Akt1 at
Ser473 (NEB) and Bad at
Ser112 or Ser136 (NEB).
Results are expressed as density ratios to actin. In some experiments,
cells were pretreated with pertussis toxin (PTX; List Biological,
Campbell, CA) for 4 h to inhibit Gi or with LY294002 (Biomol,
Plymouth, PA) for 1 h to inhibit PI-3K.
Determination of Bad complexed with Bcl-xL
Cell lysates (100 µg protein) were immunoprecipitated with rabbit anti-Bcl-xL IgG (Santa Cruz Biotechnology) before immunoblotting. The presence of Bad in anti-Bcl-xL immunoprecipitates was evaluated by 10% SDS-PAGE and immunoblotting using anti-Bad IgG (Santa Cruz Biotechnology). The same blot was then examined for Bcl-xL, and the results are shown as Bad:Bcl-xL density ratios.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
In defined medium, OPC cease to proliferate and begin to
differentiate into OLG. The lack of serum growth factors also initiates
the process of apoptosis in these cells (1, 2, 3, 4, 5). After
56 h in defined medium, 
40% of cells survive as differentiated
OLG (29). We examined the PI-3K and Akt1 activities in OPC
in defined medium for up to 72 h (Fig. 1
). The rate of decline in PI-3K and Akt
activities, determined in separate experiments, are presented together
in Fig. 1. PI-3K and Akt1 activities declined rapidly within 3–6 h in
viable cells. The rate of their decline was similar to the loss of
Bcl-2 mRNA expression under identical conditions (29).
These findings suggested that serum deprivation results in rapid loss
of signal kinases required for survival, and also Bcl-2 gene
expression.
|
We have measured the release of cyto-c and the activation of
caspase-9 in OPC in defined medium. We have detected cytoplasmic cyto-c
after 24 h, and the released cyto-c level was increased
significantly at 72 h. Increased cyto-c in supernatants was
associated with decreased cyto-c in pellet fractions (Fig. 2A). The supernatant was free
of mitochondrial contamination, as shown by the absence of cox IV in
digitonin-treated samples. The absence of cyto-c in
digitonin-permeabilized supernatant of the control cells (Fig. 2A, t = 0 point) also indicated that the
cyto-c was released from the mitochondria affected by apoptosis, not
mitochondria permeabilized by digitonin. The mitochondrial involvement
was further supported by the activation of caspase-9, as shown by the
generation of a 37-kDa caspase-9 cleavage fragment (Fig. 2B), a process requiring cyto-c release
(50).
|
Mitochondria play a central role in apoptosis induced by growth
factor deprivation and stress injuries, such as those following UV
irradiation and protein synthesis inhibition (41, 50).
Mitochondria are also involved in apoptosis induced by cytokines such
as TNF- (51). We previously showed that sublytic C5b-9
rescued OLG from apoptosis induced in vitro by serum deprivation and by
TNF-, and this rescue was associated with inhibition of caspase-3
activation (29). Because the mitochondrial pathway of
apoptosis was clearly implicated in death of OLG cultured in defined
medium (Figs. 1
and 2), the effects of C5b-9 on cyto-c and caspase-9
were investigated. OLG differentiated from OPC for 56 h were
further cultured in defined medium for 18 h, as previously
described (29, 31). OLG death occurring during this
18 h was 45% (see Fig. 6). Using this system, the effect of
sublytic C5b-9 on cyto-c release was measured. The sublytic dose of
C5b-9 was determined by trypan blue stain after treating OLG with
limiting C5b6 and excess C7, C8, and C9 (Fig. 3). As shown in Fig. 4A, C5b-9, but not C5b6 (30
µg or 18 U), caused >60% inhibition of cyto-c release. An increase
in cyto-c was seen in the corresponding pellets. Similar results were
obtained (63% inhibition) when cyto-c release was measured by ELISA
(Fig. 4B). To evaluate the caspase-9 activation, the
presence of the 17-kDa caspase-9 fragment was examined in C5b-9-treated
cells (Fig. 5). C5b-9, but not C5b6,
totally abrogated the increase in the 17-kDa fragment during the 18-h
period. These findings indicated that C5b-9 inhibits the mitochondrial
pathway of apoptosis, in which caspase-9 activated by cytosolic
cyto-c/Apaf complex plays an essential role in caspase-3-dependent cell
death (41, 50).
|
|
|
|
Both PI-3K and mitogen-activated protein kinase pathways promote
cell survival through regulation of the Bcl-2 family of proteins
(36, 37, 38, 39, 40). We examined the role of PI-3K and ERK pathways
in OLG survival induced by C5b-9. OLG derived from OPC in defined
medium for 56 h were treated with PI-3K inhibitor (10 µM
LY294002) or MEK1 inhibitors (25 µM PD98059 or 10 µM U0126) for
18 h. Cell survival, determined by the MTS assay, showed 46%
reduction in control cells in defined medium after 18 h. As shown
by Fig. 6, 75% of cell death was
reversed by C5b-9. This reversal is statistically significant
(p < 0.05). The protective effect of C5b-9 was
totally abrogated by LY294002 (Fig. 6) and partially abrogated by
inhibiting MEK1 activity (data not shown). These data suggested that
PI-3K, but not the ERK pathway, is the primary signal pathway to rescue
OLG from apoptosis. Alternatively, both the PI-3K and ERK1 pathways may
be required, because ERK1 activity can be inhibited by PI-3K inhibitors
(33, 52). The cell survival reduced below the control
level (Fig. 6, CTR, 18 h) by LY294002 may be due to PI-3K
activation by the low level of fibroblast growth factor in defined
medium.
C5b-9 induces activation of PI-3K and Akt
Because OLG survival induced by C5b-9 was inhibited by PI-3K
inhibitor, the ability of C5b-9 to activate PI-3K in OLG was assessed.
C5b-9 increased PI-3K activity to a maximum of 5-fold (Fig. 7A), similar to the effect of
C5b-9 in aortic smooth muscle cells (33). PI-3K and Akt
activities decreased with an induction of OPC/OLG apoptosis (Fig. 1).
Because Akt is considered to be the critical kinase in PI-3K-dependent
survival, Akt activation by C5b-9 was determined by in vitro kinase
assay and by assessing the phosphorylated Akt at
Ser473. Akt activity reached a maximum of
3.4-fold at 10 min and remained elevated at 40 min (Fig. 7B). Akt phosphorylation at Ser473
increased 2.5-fold over the untreated or C5b6 controls at 30 min (data
now shown).
|
Phosphorylation of Bad at Ser136 by Akt is a
critical step in PI-3K-dependent cell survival (39).
Phosphorylation of other sites, such as Ser112
and Ser155, by other kinases is also important in
down-regulating Bad activity (38, 53, 54, 55, 56, 57). Phosphorylation
of these sites neutralizes Bad by promoting the dissociation of
Bad/Bcl-xL complex and by inducing the
cytoplasmic sequestration of Bad by binding the 14-3-3 family of
proteins (40). In our system, phosphorylation at
Ser112, undetected in control cells, was
increased 4-fold by C5b-9 (Fig. 8A). Phosphorylation of Bad at
Ser136 was increased 3-fold at 20 min over the
untreated or C5b6 control levels (Fig. 8B). LY294002 and PTX
were effective in inhibiting phosphorylation of
Ser136 and Ser112.
Therefore, phosphorylation of Bad at Ser112 and
Ser136 by C5b-9 was induced by a
Gi/PI-3K-dependent pathway.
|
Phosphorylation of Bad is associated with loss of proapoptotic
activity upon its release from the Bad/Bcl-xL
complex (40, 54, 55, 56, 57). To evaluate the functional
significance of Bad phosphorylation in OLG, we examined the effect of
C5b-9 on the binding of Bad to Bcl-xL. C5b-9
reduced the level of the Bad/Bcl-xL complex by
60% at 18 h, and this was reversed by PTX (Fig. 9).
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Bad protein, which belongs to the BH3-only proteins, is essential in initiating the mitochondrial apoptosis (58). We examined Bad as a substrate for the PI-3K/Akt pathway in C5b-9-mediated OLG survival. C5b-9 induced Bad phosphorylation at Ser112 and enhanced Ser136 phosphorylation in a PI-3K- and Gi-dependent manner. The fact that the same dose of LY294002 reversed the C5b-9 rescue of OLG death and effectively blocked the phosphorylation of Bad at both serine residues strongly suggests that Bad is coordinately regulated by C5b-9 through activation of PI-3K. Similarly, growth factors can induce concomitant phosphorylation of Bad at multiple Serine residues, including Ser112, Ser136, and Ser155 (55). Whereas Akt phosphorylates Bad primarily at Ser136, but not Ser112 (39), Ser112 is phosphorylated by other kinases, such as mitochondrial protein kinase A, p65 p21-activated kinase 1, and RSK1 (38, 53, 54, 55, 56, 57, 58). RSK1 is activated by C5b-9 through ERK1 (data not shown), and ERK1 can be inhibited by PI-3K inhibitors (33). Therefore, regulation of Bad by C5b-9 may also involve an activation of kinases, other than Akt1, downstream of PI-3K. Protection of OLG from apoptosis through regulation of Bad may be mediated by inhibition of Bad/Bcl-xL complex assembly, thus increasing the Bcl-xL activity.
We previously showed that C5b-9 increases Bcl-2 synthesis in OLG (29), a process that may also be regulated by PI-3K through p70 S6 kinase which is required for protein translation. Therefore, an increase in Bcl-2 protein in OLG may increase the Bcl-2/Bax complex formation. This mechanism is thought to neutralize the proapoptotic Bax, as proposed by the rheostat model (41). Thus, full protection of OLG from apoptotic death may require both the neutralization of proapoptotic activities and enhanced activities of Bcl-2 and Bcl-xL.
In situ activation and assembly of C5b-9 occur in MS and other inflammatory and degenerative CNS disorders, as demonstrated by the presence of C5b-9 in spinal fluids and affected tissues (14, 15, 16, 17, 18, 19, 20, 59). We propose that C5b-9 may have a beneficial role by rescuing OLG from apoptotic death, thus promoting their survival and remyelination.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
2 Address correspondence and reprint requests to Dr. Moon L. Shin, Department of Pathology, University of Maryland School of Medicine, 10 South Pine Street, MSTF 600-E, Baltimore, MD 21201. E-mail address: mshin{at}umaryland.edu
3 Abbreviations used in this paper: OLG, oligodendrocytes; C5b-9, terminal complement complexes consisting of C5b, C6, C7, C8, and C9 proteins; cyto-c, cytochrome c; MS, multiple sclerosis; OPC, OLG progenitor cells identified by mAb A2B5; ERK1, extracellular signal-regulated kinase; PI-3K, phosphatidylinositol 3-phosphate kinase; MEK1, mitogen-activated protein kinase-1/ERK1; cox IV, cyto-c oxidase subunit IV; PTX, pertussis toxin; Bad, BCL2-antagonist of cell death; RSK1, ribosomal protein 5b kinase 1.
Received for publication March 14, 2001. Accepted for publication June 13, 2001.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
-amyloid in Alzheimer disease. Proc. Natl. Acad. Sci. USA 89:10016.
m) and cytochrome c release are caspase independent. J. Immunol. 163:4683.-induced injury through Akt-mediated signaling mechanisms. J. Biol. Chem. 275:16360.This article has been cited by other articles:
|
|
 |
|
  P. A. Watson, J. E. B. Reusch, S. A. McCune, L. A. Leinwand, S. W. Luckey, J. P. Konhilas, D. A. Brown, A. J. Chicco, G. C. Sparagna, C. S. Long, et al. Restoration of CREB function is linked to completion and stabilization of adaptive cardiac hypertrophy in response to exercise Am J Physiol Heart Circ Physiol, July 1, 2007; 293(1): H246 - H259. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Fosbrink, F. Niculescu, V. Rus, M. L. Shin, and H. Rus C5b-9-induced Endothelial Cell Proliferation and Migration Are Dependent on Akt Inactivation of Forkhead Transcription Factor FOXO1 J. Biol. Chem., July 14, 2006; 281(28): 19009 - 19018. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Cudrici, F. Niculescu, T. Jensen, E. Zafranskaia, M. Fosbrink, V. Rus, M. L. Shin, and H. Rus C5b-9 Terminal Complex Protects Oligodendrocytes from Apoptotic Cell Death by Inhibiting Caspase-8 Processing and Up-Regulating FLIP. J. Immunol., March 1, 2006; 176(5): 3173 - 3180. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. F. Grehan, B. K. Levay-Young, J. L. Fogelson, V. Francois-Bongarcon, B. A. Benson, and A. P. Dalmasso IL-4 and IL-13 Induce Protection of Porcine Endothelial Cells from Killing by Human Complement and from Apoptosis through Activation of a Phosphatidylinositide 3-Kinase/Akt Pathway J. Immunol., August 1, 2005; 175(3): 1903 - 1910. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Q.-L. Cui, W.-H. Zheng, R. Quirion, and G. Almazan Inhibition of Src-like Kinases Reveals Akt-dependent and -independent Pathways in Insulin-like Growth Factor I-mediated Oligodendrocyte Progenitor Survival J. Biol. Chem., March 11, 2005; 280(10): 8918 - 8928. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Niculescu, S. Weerth, F. Niculescu, C. Cudrici, V. Rus, C. S. Raine, M. L. Shin, and H. Rus Effects of Complement C5 on Apoptosis in Experimental Autoimmune Encephalomyelitis J. Immunol., May 1, 2004; 172(9): 5702 - 5706. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. NICULESCU, S. WEERTH, L. SOANE, F. NICULESCU, V. RUS, C. S. RAINE, M. L. SHIN, and H. RUS Effects of Membrane Attack Complex of Complement on Apoptosis in Experimental Autoimmune Encephalomyelitis Ann. N.Y. Acad. Sci., December 1, 2003; 1010(1): 530 - 533. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. H. Weerth, H. Rus, M. L. Shin, and C. S. Raine Complement C5 in Experimental Autoimmune Encephalomyelitis (EAE) Facilitates Remyelination and Prevents Gliosis Am. J. Pathol., September 1, 2003; 163(3): 1069 - 1080. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. P. Mycko, R. Papoian, U. Boschert, C. S. Raine, and K. W. Selmaj cDNA microarray analysis in multiple sclerosis lesions: detection of genes associated with disease activity Brain, May 1, 2003; 126(5): 1048 - 1057. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Molina-Holgado, J. M. Vela, A. Arevalo-Martin, G. Almazan, F. Molina-Holgado, J. Borrell, and C. Guaza Cannabinoids Promote Oligodendrocyte Progenitor Survival: Involvement of Cannabinoid Receptors and Phosphatidylinositol-3 Kinase/Akt Signaling J. Neurosci., November 15, 2002; 22(22): 9742 - 9753. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
