Oocyte-Secreted Growth Differentiation Factor 9 Inhibits BCL-2-Interacting Mediator of Cell Death-Extra Long Expression in Porcine Cumulus Cell
Oocyte-Secreted Growth Differentiation Factor 9 Inhibits BCL-2-Interacting Mediator of Cell Death-Extra Long Expression in Porcine Cumulus Cell
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DOI：
10.1095/biolreprod.113.108365
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发表时间：
2013-09-01
影响因子：
3.6
通讯作者：
Zeng, Shen-Ming
中科院分区：
文献类型：
--
作者：
Wang, Xian-Long;Wang, Kun;Zeng, Shen-Ming
卵母细胞分泌因子（OSFs）维持卵丘细胞凋亡的低发生率。在这份报告中，我们描述了卵母细胞的存在抑制了猪卵丘细胞中促凋亡蛋白BCL-2-细胞死亡超长相互作用介质（BIMEL）的表达。闭锁（末端脱氧核苷酸转移酶dUTP缺口末端标记阳性）卵丘细胞强烈表达BIMEL蛋白。健康卵丘-卵母细胞复合体中BIMEL的表达较低，而去除卵母细胞后，卵丘细胞中BIMEL的表达增加了约2.5倍（P < 0.5）。与裸卵共培养使BIMEL表达降至正常水平。在用外源性重组小鼠生长分化因子9（GDF 9）（一种充分表征的OSF）处理的OOX中也可以实现类似的表达模式。通过添加磷脂酰肌醇3-激酶（PI 3 K）抑制剂LY 294002来防止GDF 9的这种抑制作用。荧光素酶实验进一步证明BIM基因的表达依赖于FOXO 3a，因为BIM启动子上FOXO 3a结合位点的突变抑制了荧光素酶活性。此外，BIM启动子包含FOXO 3a结合位点的活性可以由GDF 9调节。此外，我们发现GDF 9升高磷酸化AKT和FOXO 3a的水平，并且该过程不依赖于SMAD信号通路。综上所述，我们得出结论，OSF，特别是GDF 9，通过激活PI 3 K/FOXO 3a途径维持卵丘细胞中的低水平BIMEL表达。
Oocyte-secreted factors (OSFs) maintain the low incidence of cumulus cell apoptosis. In this report, we described that the presence of oocytes suppressed the expression of proapoptotic protein BCL-2-interacting mediator of cell death-extra long (BIMEL) in porcine cumulus cells. Atretic (terminal deoxynucleotidyl transferase dUTP nick end labeling-positive) cumulus cells strongly expressed BIMEL protein. The healthy cumulus-oocyte complex exhibited a low BIMEL expression in cumulus cell while the removal of oocyte led to an about 2.5-fold (P < 0.5) increased expression in oocytectomized complex (OOX). Coculturing OOXs with denuded oocytes decreased BIMEL expression to the normal level. The similar expression pattern could also be achieved in OOXs treated with exogenous recombinant mouse growth differentiation factor 9 (GDF9), a well-characterized OSF. This inhibitory action of GDF9 was prevented by the addition of a phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Luciferase assay further demonstrated that BIM gene expression was forkhead box O3a (FOXO3a)-dependent because mutation of FOXO3a-binding site on the BIM promoter inhibited luciferase activities. Moreover, the activity of BIM promoter encompassing the FOXO3a-binding site could be regulated by GDF9. Additionally, we found that GDF9 elevated the levels of phosphorylated AKT and FOXO3a, and this process was independent of the SMAD signal pathway. Taken together, we concluded that OSFs, particularly GDF9, maintained the low level of BIMEL expression in cumulus cell through activation of the PI3K/FOXO3a pathway.