RETINOL-MEDICATED REGULATION OF SPERMATOGENESIS

维生素A已被证明是一种重要的细胞外调节因子 为了哺乳动物睾丸中生殖细胞的正常发育。 这项建议的长期目标是调查 维生素A的一种形式视黄醇的分子机制， 调节精子发生的过程。这将是 通过鉴定视黄醇的靶基因来完成- 睾丸中的调制。 当大鼠喂食缺乏维生素A的食物时，它们的睾丸 萎缩和生精上皮变性。这可以是 通过腹腔注射视黄醇完全逆转 (Morales和Griswold，内分泌学，12：432.，1987)。这个 视黄醇诱导的睾丸重新启动生精过程 生精小管上始终保持同步化。它是 假定特定的基因产物和mRNAs在 视黄醇对Sertoli细胞或 生发细胞。在这两种情况下，视黄醇反应基因 转录本或新翻译的蛋白质是绝对必要的 VAD大鼠精子发生再启动过程中的作用 睾丸。 为了研究视黄醇的功能意义- 在分子水平上诱导睾丸中的mRNA，它们将是 从cDNA文库中分离得到。具体来说，这将是 通过构建富含Lambda的cDNA文库来实现 在未杂交但视黄醇刺激的序列中。这个 非杂交序列是单链的cDNA，产生于 视黄醇诱导的大鼠视网膜组织中mRNA的消减杂交 VAD大鼠睾丸中有过量的mRNAs。 这些克隆的cDNA对于研究分子是必不可少的。 视黄醇在精子发生中的调节机制。他们会 对它们进行测序和表征，以确定它们在 睾丸。这些克隆的cDNA的表达情况将被研究。 在不同的睾丸细胞类型和不同的发育阶段 生精周期的关键。此外，这些项目所处的水平 将研究视黄醇调控的序列，即， 转录、转录后或翻译。为了澄清 视黄醇影响睾丸靶基因的分子机制 视黄醇诱导和睾丸组织的调节元件- 将在编码视黄醇的基因中进行特异性研究- 特定的蛋白质。

Vitamin A has been shown to be an essential extracellular regulator for the normal development of germ cells in the mammalian testis. It is the long term objective of this proposal to Investigate the molecular mechanism by which retinol, a form of Vitamin A, regulates the Process of spermatogenesis. This will be accomplished by identification of target genes for the retinol- modulation in the testis. When rats are fed on a Vitamin A-deficient diet, their testes atrophy and their seminiferous epithelium degenerate. This can be completely reversed by an intraperitoneal injection of retinol (Morales and Griswold, Endocrinology, 12: 432.,1987). The retinol-induced testes reinitiate the spermatogenic process in a synchronized manner all along the seminiferous tubules. It is Presumed that sPecific gene Products and mRNAs are synthesized in direct response to retinol in either the Sertoli cells or in the germinal cells. In either case, the retinol-responsive mRNA transcripts or newly translated proteins are absolutely essential in the reinitiation process of spermatogenesis in the VAD rat testes. In order to investigate the functional significance of the retinol- induced mRNAs in the testes at the molecular level, they will be isolated from a cDNA library. Specifically, this will be accomplished by the construction of a Lambda cDNA library enriched in the unhybridized but retinol-stimulated sequences. The unhybridized sequences are single stranded cDNAs generated in the subtractive hybridization of the mRNAs from the retinol-induced testis with an excess of mRNAs from the VAD rat testes. These cloned cDNAs are essential to investigate the molecular mechanism of retinol regulation during spermatogenesis. They will be sequenced and characterized to identify their function in the testis. The expression of these cloned cDNAs will be investigated in the different testis cell types and during the different stages of the spermatogenic cycle. In addition, the level at which these sequences are regulated by retinol will be investigated, i.e., transcription, post-transcription or translation. To elucidate the molecular mechanism of retinol on testicular target genes, the regulatory elements for the retinol induction and testis tissue- specificity will be investigated in the genes encoding the retinol- specific proteins.