Department of Experimental Medicine, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China.
Department of Experimental Medicine, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China.
J Biol Chem. 2011 Dec 9;286(49):42211-42220. doi: 10.1074/jbc.M111.296905. Epub 2011 Oct 6.
Protein kinase B (Akt) plays important roles in regulation of cell growth and survival, but while many aspects of its mechanism of action are known, there are potentially additional regulatory events that remain to be discovered. Here we detected a 36-kDa protein that was co-immunoprecipitated with protein kinase Bβ (Akt2) in OVCAR-3 ovarian cancer cells. The protein was identified to be glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by MALDI-TOF/TOF MS, and the interaction of Akt2 and GAPDH was verified by reverse immunoprecipitation. Our further study showed that Akt2 may suppress GAPDH-mediated apoptosis in ovarian cancer cells. Overexpression of GAPDH increased ovarian cancer cell apoptosis induced by H(2)O(2), which was inhibited by Akt2 overexpression and restored by the PI3K/Akt inhibitor wortmannin or Akt2 siRNA. Akt2 phosphorylated Thr-237 of GAPDH and decreased its nuclear translocation, an essential step for GAPDH-mediated apoptosis. The interaction between Akt2 and GAPDH may be important in ovarian cancer as immunohistochemical analysis of 10 normal and 30 cancerous ovarian tissues revealed that decreased nuclear expression of GAPDH correlated with activation (phosphorylation) of Akt2. In conclusion, our study suggests that activated Akt2 may increase ovarian cancer cell survival via inhibition of GAPDH-induced apoptosis. This effect of Akt2 is partly mediated by its phosphorylation of GAPDH at Thr-237, which results in the inhibition of GAPDH nuclear translocation.
蛋白激酶 B（Akt）在调节细胞生长和存活方面发挥着重要作用，但尽管其作用机制的许多方面已经为人所知，但仍有可能发现其他潜在的调节事件。在这里，我们在卵巢癌细胞 OVCAR-3 中检测到一种 36 kDa 的蛋白质，它与蛋白激酶 Bβ（Akt2）共同免疫沉淀。通过 MALDI-TOF/TOF MS 将该蛋白质鉴定为甘油醛-3-磷酸脱氢酶（GAPDH），并通过反向免疫沉淀验证了 Akt2 和 GAPDH 的相互作用。我们的进一步研究表明，Akt2 可能抑制卵巢癌细胞中 GAPDH 介导的细胞凋亡。过表达 GAPDH 增加了卵巢癌细胞中 H2O2 诱导的细胞凋亡，而过表达 Akt2 可抑制这种作用，并用 PI3K/Akt 抑制剂 wortmannin 或 Akt2 siRNA 可恢复这种作用。Akt2 磷酸化 GAPDH 的 Thr-237 并减少其核转位，这是 GAPDH 介导的细胞凋亡的必要步骤。Akt2 和 GAPDH 之间的相互作用在卵巢癌中可能很重要，因为对 10 个正常和 30 个癌性卵巢组织的免疫组织化学分析表明，GAPDH 的核表达减少与 Akt2 的激活（磷酸化）相关。总之，我们的研究表明，激活的 Akt2 可能通过抑制 GAPDH 诱导的细胞凋亡来增加卵巢癌细胞的存活。Akt2 的这种作用部分是通过其在 Thr-237 处磷酸化 GAPDH 来介导的，这导致 GAPDH 核转位的抑制。
