PROTO-ONCOGENES IN GAMETOGENESIS AND EARLY DEVELOPMENT

该项目的总体目标是了解原型的作用， 配子发生和哺乳动物胚胎早期发育中的癌基因。 拟议的研究重点是调节机制， 在减数分裂中起关键作用的c-mos基因的转录 脊椎动物的卵母细胞。 c-mos的转录受到严格的 组织特异性调节，导致其在雄性中特异性表达 和女性生殖细胞。对c-mos的这种监管不仅需要 在生殖细胞中实现适当的c-mos表达， 体细胞中的不适当表达，这可能导致 细胞死亡或肿瘤转化。 值得注意的是，C- mos表达在胚胎发生早期下调，这可能是 防止胚胎分裂停滞， Mos作为细胞生长抑制因子的作用。 c-mos在体细胞中的转录被一个负性的 调控元件（NRE）上游的c-mos启动子。 此外，本发明还提供了一种方法， 最近的研究已经确定了一种候选体细胞阻遏物， 与c-mos NRE内的功能元件结合。 我们现在计划 分离阻遏蛋白的cDNA克隆，并表征其 抑制c-mos转录的作用机制， 其他生殖细胞特异性基因。 c-mos在卵母细胞中的表达不受NRE的影响， 仅需要最少的启动子，包括起始子（Inr）元件。 这些发现提示了c-mos在卵母细胞中转录的假说 这是由高水平的基础转录活性引起的， 抑制在两细胞胚胎中。 这将进一步调查 c-mos Inr基因转录活性的研究 卵母细胞和胚胎，连同表达分析， c-mos阻遏物在胚胎发育过程中的功能。 拟议的研究有三个具体目标： 1. 一个体细胞cDNA克隆的分离和鉴定 c-mos转录的阻遏物。 2. c-mos的结构/功能分析及机理研究 阻遏作用 3. 卵母细胞c-mos转录调控的研究 早期胚胎

The overall goal of the project is understanding the roles of proto- oncogenes in gametogenesis and early development of mammalian embryos. The proposed research is focused on the mechanisms that regulate transcription of the c-mos gene, which plays a critical role in meiosis of vertebrate oocytes. Transcription of c-mos is subject to stringent tissue--specific regulation, leading to its specific expression in male and female germ cells. Such regulation of c-mos is needed not only to achieve appropriate c-mos expression in germ cells but also to prevent inappropriate expression in somatic cells, which can result in either cell death or neoplastic transformation. It is also noteworthy that c- mos expression is downregulated early in embryogenesis, which may be necessary to prevent arrest of embryonic cleavage divisions resulting from the action of Mos as a cytostatic factor. Transcription of c-mos in somatic cells is suppressed by a negative regulatory element (NRE) upstream of the c-mos promoter. In addition, recent studies have identified a candidate somatic cell repressor that binds to a functional element within the c-mos NRE. We now plan to isolate a cDNA clone of the repressor protein and to characterize its mechanism of action in suppressing transcription of c-mos, and possibly other germ cell-specific genes, in somatic cells. Expression of c-mos in oocytes, which is not affected by the NRE, requires only a minimal promoter, including an initiator (Inr) element. These findings suggest the hypothesis that c-mos transcription in oocytes results from a high level of basal transcription activity, which is then suppressed in two-cell embryos. This will be investigated by further studies of the activity of the c-mos Inr in directing transcription in oocytes and embryos, together with analysis of the expression and function of the c-mos repressor during embryonic development. The proposed studies have three specific aims: 1. Isolation and characterization of a cDNA clone for a somatic cell repressor of c-mos transcription. 2. Structure/function analysis and studies of the mechanism of c-mos repressor action. 3. Investigation of the regulation of c-mos transcription in oocytes and early embryos.