REGULATION OF SPHINGOMYELIN PATHWAY IN THE CORPUS LUTEUM

黄体（CL）的主要功能是合成和 分泌孕酮，使子宫静止， 和维持妊娠。 任何功能的过早中断 黄体功能不全会导致妊娠失败， 周期性和生殖效率的降低。 的抑制 类固醇合成（功能回归），最终 破坏细胞内稳态（结构退化）， 统称为黄体溶解。 最近，细胞因子 在黄体溶解中起积极作用;然而， 它们引起细胞毒活性的机制仍然是 演示。最近的证据表明，细胞死亡的信号， 无论是通过TNF α、IFN γ、FAS配体或其他应激相关的 刺激，通过鞘磷脂途径介导。巧合的是，这些 同样的因素也与类固醇的抑制和死亡有关 的CL。 细胞因子对酸性鞘磷脂酶的激活导致 神经酰胺水平升高 随后，应激诱导的神经酰胺被 据信优先通过细胞质应激发出信号 活化蛋白激酶（SAPK）是丝裂原活化的一员， 蛋白激酶级联反应（MAPKs）。 MAPK是细胞质酶 负责将细胞表面产生的信号 在细胞核中它们通过磷酸化 转录因子 我们假设，细胞因子，以及其他 细胞毒性刺激，将通过鞘磷脂启动细胞死亡 途径及其第二信使神经酰胺。 此外，委员会认为， 神经酰胺的随后增加将激活SAPKs， 最终磷酸化特定的转录因子， 细胞死亡，因此在从 类固醇生成的功能性抑制对 CL.为了解决这一假设，我们提出了以下目标：（1） 确定是否有特定的细胞因子参与调节 黄体退化的功能和结构方面激活了 鞘磷脂途径(2)描述对以下物质的多效性反应 细胞因子（TNF α-INF γ），如通过 ERK和/或SAPKs/JNK和（3）转录因子c-fos和c-jun 在黄体细胞中。(4)确定是否单独使用类固醇抑制 可以激活培养的牛黄体细胞中的鞘磷脂途径。 (5)确定半胱天冬酶在神经胺活化中的作用。 的 实验将利用牛黄体的明确的原代培养物 细胞，并采用互补的细胞和分子技术， 解决目标。 该项目有望提供新的信息 在黄体溶解过程中的细胞机制。

The primary function of the corpus luteum (CL) is to synthesize and secrete progesterone to provide uterine quiescence for the establishment and maintenance of pregnancy. Any premature disruption in the function of the corpus luteum can result in a loss of pregnancy, irregular cyclicity, and a reduction in reproductive efficiency. The inhibition of steroid synthesis (functional regression), and the eventual disruption of cellular homeostasis (structural regression), is collectively described as luteolysis. More recently, cytokines have been implicated in an active role in luteolysis; yet the exact mechanisms by which they elicit their cytotoxic activity remains to be demonstrated. Recent evidence suggests that the signal for cell death, whether it be by TNFalpha, IFNgamma, FAS ligand or other stress-related stimuli, is mediated via the sphingomyelin pathway. Coincedently, these same factors have also been implicated in steroid inhibition and demise of the CL. Activation of the acid-sphingomyelinase by cytokines results in elevated ceramide levels. Subsequently, stress-induced ceramide is believed to preferentially signal through the cytoplasmic stress activated protein kinase (SAPK) a member of the mitogen activated protein kinase cascade (MAPKs). MAPKs are cytoplasmic enzymes responsible for translating the signal generated on the cell surface to the nucleus where they regulate transcription by phosphorylating transcription factors. We hypothesize that cytokines, as well as other cytotoxic stimuli, will initiate cell death via the sphingomyelin pathway and its second messenger ceramide in luteal cells. Furthermore, subsequent increases in ceramide will activate SAPKs which will ultimately phosphorylate specific transcription factors implicated in cellular demise and therefore play a role in the transition from functional inhibition of steroidogenesis to structural regression of the CL. To address this hypothesis we have proposed the following aims: (1) Determine if specific cytokines implicated in the regulation of the functional and structural aspects of luteal regression activate the sphingomyelin pathway. (2) Characterize the pleiotropic responses to cytokines (TNFalpha-INFgamma) as determined by the relative changes in ERKs and/or SAPKs/JNK and (3) the transcription factors c-fos and c-jun in luteal cells. (4) Determine whether or not steroid inhibition alone can activate the sphingomyelin pathway in cultured bovine luteal cells. (5) Determine the role of capase enzymes in ceramine activation. The experiments will utilize well defined primary cultures of bovine luteal cells and employ complimentary cellular and molecular techniques to address the aims. This project is expected to provide novel information on the cellular mechanisms involved in the process of luteolysis.