R-RAS PROMOTES APOPTOSIS CAUSED BY GROWTH-FACTOR DEPRIVATION VIA A BCL-2 SUPPRESSIBLE MECHANISM

被引：110

作者：

WANG, HG

MILLAN, JA

COX, AD

DER, CJ

RAPP, UR

BECK, T

ZHA, HB

REED, JC

机构：

[1] LA JOLLA CANC RES FDN, LA JOLLA, CA 92037 USA

[2] UNIV N CAROLINA, DEPT PHARMACOL, FLOB, CHAPEL HILL, NC 27599 USA

[3] NCI, FREDERICK RES FACIL, VIRAL ONCOL LAB, FREDERICK, MD 21702 USA

来源：

JOURNAL OF CELL BIOLOGY | 1995年 / 129卷 / 04期

关键词：

D O I：

10.1083/jcb.129.4.1103

中图分类号：

Q2 [细胞生物学];

学科分类号：

071009 ; 090102 ;

摘要：

The Bcl-2 protein is an important regulator of programmed cell death, but the biochemical mechanism by which this protein prevents apoptosis remains enigmatic. Recently, Bcl-2 has been reported to physically interact with a member of the Ras superfamily of small GTPases, p23-R-Ras. To examine the functional significance of R-Ras for regulation of cell death pathways, the IL-3-dependent cells 32D.3 and FL5.12 were stable transfected with expression plasmids encoding an activated form (38 Glycine --> Valine) of R-Ras protein. R-Ras(38V)-producing 32D.3 and FL5.12 cells experienced increased rates of apoptotic cell death relative to control transfected cells when deprived of IL-3. Analysis of several independent clones of transfected 32D.3 cells revealed a correlation between higher levels of R-Ras protein and faster rates of cell death upon withdrawal of IL-3 from cultures. 32D.3 cells contransfected with R-Ras(38V) and Bcl-2 exhibited prolonged cell survival in the absence of IL-3, equivalent to 32D.3 cells transfected with Bcl-2 expression plasmids alone. R-Ras(38V) also increased rates of cell death in serum-deprived NIH-3T3 cells, and Bcl-2 again abrogated most of this effect. The ratio of GTP and GDP bound to R-Ras(38V) was not significantly different in control 32D.3 cells vs those that overexpressed Bcl-2, indicating that Bcl-2 does not abrogate R-Ras-mediated effects on cell death by altering R-Ras GDP/GTP regulation. Moreover, purified Bcl-2 protein had no effect on the GTPase activity of recombinant wild-type R-Ras in vitro. When expressed in Sf9 cells using recombinant baculoviruses, R-Ras(38V) bound to and induced activation of Raf-1 kinase irrespective of whether Bcl-2 does not nullify R-Ras effects by interfering with R-Ras-mediated activation of Raf-1 kinase. Taken together, these findings suggest that R-Ras enhances the activity of a cell death pathway in growth factor-deprived cells and imply that Bcl-2 acts downstream of R-Ras to promote cell survival.

引用

页码：1103 / 1114

页数：12

共 59 条

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