Prostaglandin F2α-mediated Activation of Apoptotic Signaling Cascades in the Corpus Luteum during Apoptosis
Prostaglandin F2α-mediated Activation of Apoptotic Signaling Cascades in the Corpus Luteum during Apoptosis
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DOI：
10.1074/jbc.m409596200
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发表时间：
2005-03
影响因子：
4.8
通讯作者：
V. Yadav;G. Lakshmi;R. Medhamurthy
中科院分区：
文献类型：
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作者：
V. Yadav;G. Lakshmi;R. Medhamurthy
前列腺素 F2α (PGF2α) 通过 G 蛋白偶联受体发挥作用，已被证明可诱导许多物种黄体细胞凋亡。进行研究以表征在 PGF2α 诱导的牛黄体溶解过程中最终导致黄体组织凋亡的凋亡信号级联的变化，其中在外源 PGF2α 处理后 18 小时即可证明细胞凋亡的启动。对凋亡信号级联元件的内在臂的分析表明，早在治疗后 4 小时，PGF2α 注射就引发黄体组织中 Bax 与 Bcl-2 的比率增加，并一直保持升高状态直至 18 小时。这种增加与 4-12 小时活性 caspase-9 和 -3 蛋白水平和活性的升高 (p < 0.05) 相关，但仅在治疗后 18 小时才观察到活性突增，这不能用 Bax/Bcl-2 比率的变化或 Bax 向线粒体易位的变化来解释。对黄体组织中 FasL/Fas 死亡受体级联的检查显示，18 小时时 FasL 和 Fas 的表达增加，同时 caspase-8 活性和 Bid 水平显着（p < 0.05）诱导。此外，在假孕大鼠模型中，在外源性和内源性细胞凋亡信号级联下游的特定半胱天冬酶抑制剂的囊内给药揭示了外源性细胞凋亡信号级联在PGF2α治疗期间介导黄体组织细胞凋亡中的更重要。研究发现，负责 PGF2α 诱导的细胞凋亡 DNA 片段化的 DNase 是 Ca2+/Mg2+ 依赖性、温度敏感的 DNase，并且在中性 pH 条件下具有最佳活性。这种假定的 DNase 被半胱天冬酶激活的 DNase 的重组抑制剂抑制，并且从黄体裂解物中免疫耗竭半胱天冬酶激活的 DNase 消除了观察到的 DNA 片段化活性。总之，这些数据首次证明了 PGF2α 诱导黄体细胞凋亡过程中凋亡信号级联的时间和空间变化。
Prostaglandin F2α (PGF2α) acting via a G protein-coupled receptor has been shown to induce apoptosis in the corpus luteum of many species. Studies were carried out to characterize changes in the apoptotic signaling cascade(s) culminating in luteal tissue apoptosis during PGF2α-induced luteolysis in the bovine species in which initiation of apoptosis was demonstrable at 18 h after exogenous PGF2α treatment. An analysis of intrinsic arm of apoptotic signaling cascade elements revealed that PGF2α injection triggered increased ratio of Bax to Bcl-2 in the luteal tissue as early as 4 h posttreatment that remained elevated until 18 h. This increase was associated with the elevation in the active caspase-9 and -3 protein levels and activity (p < 0.05) at 4–12 h, but a spurt in the activity was seen only at 18 h posttreatment that could not be accounted for by the changes in the Bax/Bcl-2 ratio or changes in translocation of Bax to mitochondria. Examination of luteal tissue for FasL/Fas death receptor cascade revealed increased expression of FasL and Fas at 18 h accompanied by a significant (p < 0.05) induction in the caspase-8 activity and truncated Bid levels. Furthermore, intrabursal administration of specific caspase inhibitors, downstream to the extrinsic and intrinsic apoptotic signaling cascades, in a pseudopregnant rat model revealed a greater importance of extrinsic apoptotic signaling cascade in mediating luteal tissue apoptosis during PGF2α treatment. The DNase responsible for PGF2α-induced apoptotic DNA fragmentation was found to be Ca2+/Mg2+-dependent, temperature-sensitive DNase, and optimally active at neutral pH conditions. This putative DNase was inhibited by the recombinant inhibitor of caspase-activated DNase, and immunodepletion of caspase-activated DNase from luteal lysates abolished the observed DNA fragmentation activity. Together, these data demonstrate for the first time temporal and spatial changes in the apoptotic signaling cascades during PGF2α-in-duced apoptosis in the corpus luteum.