|
- 积分
- 156
- 威望
- 156
- 包包
- 1330
|
Ischemia induces regulator of G protein signaling 2 (RGS2) protein# \7 w, s/ A1 U! u% M8 u7 y2 q
upregulation and enhances apoptosis in astrocytes
( N, P- q, f$ E- q& |Mehari Endale,1* Sung Dae Kim,1* Whi Min Lee,1 Sangseop Kim,2 Kyoungho Suk,2 Jae Youl Cho,3% b) T% ?8 m- g1 `
Hwa Jin Park,4 Yadav Wagley,5 Suk Kim,6 Jae-Wook Oh,5 and Man Hee Rhee1
* R, n! y$ e( s, y6 [% {! j7 x
) I W/ d" o4 ^4 [: hEndale M, Kim SD, Lee WM, Kim S, Suk K, Cho JY, Park HJ,& E! y/ T% D( `
Wagley Y, Kim S, Oh JW, Rhee MH. Ischemia induces regulator of G+ [% g% X$ Q( R9 h- f
protein signaling 2 (RGS2) protein upregulation and enhances apoptosis
+ g" P; K' P# m& D$ U% hin astrocytes. Am J Physiol Cell Physiol 298: C611–C623, 2010. First9 E2 C/ ]' v* W7 G- Q
published December 23, 2009; doi:10.1152/ajpcell.00517.2008.—Regulator2 e( h. f5 Y# D3 K6 F
of G protein signaling (RGS) family members, such as RGS2,
9 z. t5 Z" E, S) L* z" Dinteract with G subunits of heterotrimeric G proteins, accelerating
1 ~3 F$ N, s, h' [+ B3 Y# Jthe rate of GTP hydrolysis and attenuating the intracellular signaling
) o2 o7 R, M) [7 Ctriggered by the G protein-coupled receptor-ligand interaction.2 p8 u! B. @# R% {" w
They are also reported to regulate G protein-effector interactions; p# P, E/ v$ e
and form multiprotein signaling complexes. Ischemic stress-induced. K. m% ^/ Z5 A# I2 K: ]* x
changes in RGS2 expression have been described in astrocytes,3 G; W* N/ U* a, j& o) T+ H
and these changes are associated with intracellular signaling
8 W9 c# q! v2 }) ecascades, suggesting that RGS2 upregulation may be an important
3 L! X Q9 F9 Cmechanism by which astrocytes may regulate RGS2 function in
2 t* t" j b6 Eresponse to physiological stress. However, information on the
4 \; T( v/ _& u+ Vfunctional roles of stress-induced modulation of RGS2 protein8 A; B/ c F& g
expression in astrocyte function is limited. We report the role of( h6 q! r3 U6 u9 V- ~ q
ischemic stress in RGS2 protein expression in rat C6 astrocytoma
' r( K& x/ X, M8 W4 q1 I9 n! Ccells and primary mouse astrocytes. A marked increase in RGS2
0 h% n ], T# w# x0 P% roccurred after ischemic stress induced by chemicals (sodium azide9 x) X- Q2 W- B9 u
and 2-deoxyglucose) or oxygen-glucose deprivation (OGD, real
7 Q' S2 ]' a" Xischemia). RGS2 mRNA expression was markedly enhanced by 1
( F) x( C$ c% A8 `h of exposure to chemical ischemia or 6 h of OGD followed by 2
8 c# {2 m: b- h N! x& o- c$ Zor 6 h of recovery, respectively. This enhanced expression in
8 x, t" s$ T* o# ^primary astrocytes and C6 cells was restored to baseline levels
2 r6 Z; R! k# C1 l- P) k2 Wafter 12 h of recovery from chemically induced ischemic stress or
+ Z3 \: [3 Q# c( P! ~9 [4 – 6 h of recovery from OGD. RGS2 protein was also significantly0 m" p: M/ n _3 H( I1 E7 H" Q
expressed at 12–24 h of recovery from ischemic insult. Ischemiainduced0 x! [) ]1 C# c1 I& S7 g
RGS2 upregulation was associated with enhanced apoptosis.
) y6 b. W" m% `, b$ D4 hIt significantly increased annexin V-positive cells, cleaved% ~0 t% b9 e [/ F- C1 o M
caspase-3, and enhanced DNA ladder formation and cell cycle" E1 @9 P7 K' {$ g
arrest. However, a small interfering RNA (siRNA)-mediated RGS2
; D4 e* r8 G, W; I+ n% uknockdown reversed the apoptotic cell death associated with ischemia-
2 H% d. ^ _& V, }4 pinduced RGS2 upregulation. Upregulated RGS2 was significantly) A/ w( b0 @# Z0 p5 `5 P
inhibited by SB-203580, a p38 MAPK inhibitor. Rottlerin,
8 y1 |2 V1 j5 u: K5 ja potent inhibitor of PKC, completely abrogated the increased9 \; W+ G/ g s& \. ~/ f4 ]% J+ X g; e
RGS2 expression. We also examine whether ischemia-induced- n& v5 n' y% u; | F
RGS2-mediated apoptosis is affected by siRNA-targeted endogenous
0 A' x, \# J$ GPKC downregulation or its phosphorylation. Although
& i6 z6 L: Z' }# s, QRGS2 upregulation was not affected, siRNA transfection significantly' G- i! W8 f3 D3 n1 C. T
suppressed endogenous PKC mRNA and protein expresexpressions.
! D4 B% `) h- S" uIschemia-induced PKC phosphorylation and caspase-3
7 `4 p1 ?0 s. @4 |# lcleavage were dose dependently inhibited by PKC knockdown,% _ u/ r" n( m# f9 K, J
and this endogenous PKC suppression reversed ischemia-induced+ |# p: V+ Z* p! l; @/ B* G
annexin V-positive cells. This study suggests that ischemic stress
& i7 k; U& T- W, e. D2 \2 [3 v! c0 zincreases RGS2 expression and that this condition contributes to
7 e+ _& }+ v; t2 |enhanced apoptosis in C6 cells and primary astrocytes. The signaling- ^0 s6 O9 v/ s& _
it follows may involve PKC and p38 MAPK pathways.
/ N% |& u7 B; S. [希望对你有用 |
附件: 你需要登录才可以下载或查看附件。没有帐号？注册
-
总评分: 威望 + 2
包包 + 5
查看全部评分
|
发表于 2011-8-24 05:41
