Reproductive Biochemistry of Testis Specific LDH-X

描述（由申请人提供）：我研究的主要目标是确定和了解乳酸脱氢酶C4 （LCH- C4）在哺乳动物睾丸中的功能。实现这一目标应该增加我们对精子发生的分子基础的基本知识。许多生殖细胞蛋白和酶已经被描述，但很少有像LDH- C4这样明确的功能，LDH- C4是一种关键的代谢酶，在精子发生和精子中具有重要的催化功能。过去几年的许多研究证实，精母细胞的代谢倾向于从支持细胞中提取乳酸作为主要的能量来源。糖酵解是精子利用底物的首选途径。现在有令人惊讶的证据表明，LDH-C4在精子成熟中的功能可能超越酶促作用，在精子中起结构作用，在生殖上皮中起调节作用。这些发现支持了我的假设，即LDH-C4是完成精子发生和精子功能所必需的。我的实验室对这种同工酶的结构、生化和分子表征做出了贡献，最近对调节原代精母细胞同源基因表达的顺式和反式元件进行了描述。这种深入的分析为该蛋白本身功能的实验提供了平台，并作为精子发生分子分析的模型。我们的基本原理是理解Idhc表达的调控与其作为细胞特异性蛋白的特殊功能有关，并且进一步的调控机制可能反映了那些负责激活精子发生所必需的基因的机制。本提案的具体目标是：1)鉴定和表征负责ldhc生殖细胞特异性表达的转录因子；2)针对小鼠LDHC基因的破坏；3)描述LDH-C4在睾丸和精子中的催化和非催化功能，确定将LDH-C4束缚在纤维鞘上的蛋白质-蛋白质相互作用，以及可能调节睾丸基因翻译的蛋白质-核酸相互作用。这些特定目标的完成将进一步加深我们对LDH-C4功能、睾丸特异性基因调控以及正常精子发生和精子功能所需的大分子相互作用的理解。

DESCRIPTION (provided by applicant): The primary goal of my research is to determine and understand the function of lactate dehydrogenase C4 (LCH- C4) in the mammalian testis. Achieving this goal should increase our fundamental knowledge about the molecular basis of spermatogenesis. Many germ cell proteins and enzymes have been described, but few are as well defined functionally as LDH- C4, which is a key metabolic enzyme with an important catalytic function during spermatogenesis and in spermatozoa. Many studies over the past several years have confirmed that spermatocyte metabolism prefers lactate from Sertoli Cells as a primary energy source. Glycolysis is the preferred route of substrate utilization by sperm. There is now surprising evidence that the function of LDH-C4 in sperm maturation may go beyond the enzymatic to a structural role in the sperm and a regulatory role in the germinal epithelium. These findings support my hypothesis that LDH-C4 is required for both the completion of spermatogenesis and for sperm function. My laboratory has contributed to the structural, biochemical and molecular characterization of this isozyme and more recently to a description of cis and trans elements regulating expression of the cognate gene in primary spermatocytes. This in depth analysis provides the platform for experimentation on the function of this protein itself and as a model in the molecular analysis of spermatogenesis. Our rationale is that understanding the regulation of Idhc expression relates to its specialized function as a cell specific protein and further that the regulatory mechanisms are likely to reflect those responsible for activating genes generally essential to spermatogenesis. The specific aims of this proposal are: 1) identify and characterize the transcription factor(s) responsible for germ cell specific expression of ldhc; 2) to target disruption of the ldhc gene in mice; 3) to describe both catalytic and non-catalytic functions of LDH-C4 in testis and sperm, identifying protein-protein interactions that tether LDH-C4 to the fibrous sheath, and protein-nucleic acid interactions that may regulate testis gene translation. Completion of these specific aims will further our understanding of LDH-C4 function, of testis specific gene regulation and of macromolecular interactions necessary for normal spermatogenesis and sperm function.