Department of Obstetrics and Gynecology, Morehouse School of Medicine, Atlanta, GA, USA.
Life Sci. 2011 Aug 29;89(9-10):295-303. doi: 10.1016/j.lfs.2011.06.022. Epub 2011 Jul 7.
Ceramide is a key factor in inducing germ cell apoptosis by translocating from cumulus cells into the adjacent oocyte and lipid rafts through gap junctions. Therefore studies designed to elucidate the mechanistic pathways in ceramide induced granulosa cell (GC) apoptosis and follicular atresia may potentially lead to the development of novel lipid-based therapeutic strategies that will prevent infertility and premature menopause associated with chemo and/or radiation therapy in female cancer patients. Our previous studies have shown that Prohibitin (PHB) is intimately involved in GCs differentiation, atresia, and luteolysis.
In the present study, we have examined the functional effects of loss-/gain-of-function of PHB using adenoviral technology in delaying apoptosis induced by the physiological ligand ceramide in rat GCs.
Under these experimental conditions, exogenous ceramide C-8 (50 μM) augmented the expression of mitochondrial PHB and subsequently cause the physical destruction of GC by the release of mitochondrial cytochrome c and activation of caspase-3. In further studies, silencing of PHB expression by adenoviral small interfering RNA (shRNA) sensitized GCs to ceramide C8-induce apoptosis. In contrast, adenovirus (Ad) directed overexpression of PHB in GCs resulted in increased PHB content in mitochondria and delayed the onset of ceramide induced apoptosis in the infected GCs.
Taken together, these results provide novel evidences that a critical level of PHB expression within the mitochondria plays a key intra-molecular role in GC fate by mediating the inhibition of apoptosis and may therefore, contribute significantly to ceramide induced follicular atresia.
神经酰胺通过缝隙连接从卵丘细胞转移到临近的卵母细胞和脂筏中，是诱导生殖细胞凋亡的关键因素。因此，阐明神经酰胺诱导颗粒细胞（GC）凋亡和卵泡闭锁的机制途径的研究，可能会促使开发新的基于脂质的治疗策略，预防与女性癌症患者的化疗和/或放疗相关的不孕和过早绝经。我们之前的研究表明，抑制素（PHB）与 GC 的分化、闭锁和黄体溶解密切相关。
本研究采用腺病毒技术，研究了 PHB 的功能缺失和功能获得对大鼠 GC 中由生理配体神经酰胺诱导的凋亡的影响。
在这些实验条件下，外源性神经酰胺 C-8（50 μM）增加了线粒体 PHB 的表达，随后通过释放线粒体细胞色素 c 和激活 caspase-3 导致 GC 的物理破坏。进一步的研究表明，腺病毒小干扰 RNA（shRNA）沉默 PHB 表达可使 GC 对神经酰胺 C8 诱导的凋亡敏感。相反，腺病毒（Ad）在 GC 中过表达 PHB 导致线粒体中 PHB 含量增加，并延迟了感染 GC 中神经酰胺诱导的凋亡的发生。
综上所述，这些结果提供了新的证据，表明线粒体中 PHB 的表达水平在 GC 命运中发挥关键的分子内作用，通过抑制凋亡来介导，因此可能对神经酰胺诱导的卵泡闭锁有重要贡献。
