Althoefer H, Eversole-Cire P, Simon M I
Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
J Biol Chem. 1997 Sep 26;272(39):24380-6. doi: 10.1074/jbc.272.39.24380.
We investigated the effect of expression of constitutively active Galpha mutants on cell survival. Transfection of constitutively active Galphaq and Galpha13 in two different cell lines caused condensation of genomic DNA and nuclear fragmentation. Endonuclease cleavage of genomic DNA was followed by labeling the DNA fragments and subsequent flow cytometric analysis. The observed cellular phenotype was identical to the phenotype displayed by cells undergoing apoptosis. To distinguish between the apoptosis-inducing ability of the two Galpha-subunits, the signaling pathways involved in this cellular function were investigated. Whereas Galphaq induced apoptosis via a protein kinaseC-dependent pathway, Galpha13 caused programmed cell death through a pathway involving the activation of the small G-protein Rho. Both of the pathways leading to apoptosis were blocked by overexpression of bcl-2. In contrast to other apoptosis-inducing systems, expression of constitutively active Galphaq and Galpha13 triggered apoptosis in high serum as well as in defined medium.
我们研究了组成型活性Gα突变体的表达对细胞存活的影响。在两种不同的细胞系中转染组成型活性Gαq和Gα13会导致基因组DNA凝聚和核碎片化。基因组DNA经核酸内切酶切割后，对DNA片段进行标记，随后进行流式细胞术分析。观察到的细胞表型与经历凋亡的细胞所显示的表型相同。为了区分这两种Gα亚基的凋亡诱导能力，对参与这种细胞功能的信号通路进行了研究。Gαq通过蛋白激酶C依赖性途径诱导凋亡，而Gα13则通过涉及小G蛋白Rho激活的途径导致程序性细胞死亡。两条导致凋亡的途径均被bcl-2的过表达所阻断。与其他凋亡诱导系统不同，组成型活性Gαq和Gα13的表达在高血清以及限定培养基中均能触发凋亡。
