Germ Cell Differentiation in Drosophila

果蝇生殖细胞分化

• 批准号: 6823790
• 负责人: DENNIS M MCKEARIN
• 金额: $ 33.54万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-05-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6823790
• 关键词: Drosophilidae; arthropod genetics; biological signal transduction; cell cell interaction; cell differentiation; cell growth regulation; cell type; cytogenetics; developmental genetics; fertility; gene induction /repression; gene interaction; gene mutation; genetic regulatory element; genetic screening; genetic transcription; laboratory mouse; laboratory rabbit; molecular biology; molecular cloning; molecular genetics; oogenesis; stem cells; transcription factor; yeast two hybrid system

DESCRIPTION (provided by applicant): Simultaneous self-renewing and asymmetric cell divisions are a hallmark of stem cells. We can now provide a mechanism for how the germline stem cells of Drosophila accomplish this feat. Dpp signaling in the stem cell niche blocks transcription of the key cystoblast differentiation factor bam in the stem cell. It is not clear, however, why the cystoblast does not also respond to Dpp signaling. The goal of the work proposed here seeks a deeper and mechanistic understanding of additional niche signaling that might explain the differential responses of stem cell and cystoblast. Specific Aim 1. MECHANISMS MAINTAINING GERMLINE STEM CELLS (GSCs). Determine roles of multiple GSC maintenance factors using tools developed to assay bam transcriptional activation and to manipulate dpp-signaling levels. Determine if other niche signaling pathways act through dpp signaling or independent of dpp signaling. Specific Aim 2. MECHANISMS THAT DRIVE CYSTOBLAST (CB) DIFFERENTIATION. Test hypothesis that arises from preliminary results - pre-CBs express dpp signaling antagonist. Determine the identity, time of action and regulation of antagonist. Specific Aim 3. MOLECULAR BIOLOGY OF THE BAM GENE SILENCING MECHANISM. Fully characterize the cis-active elements and trans-acting factors involved in the silencing mechanism. Test if Schnurri works with Mad to quench bam transcription. The experimental approaches employ mitotic clone tests of the relevance of shn for bam expression patterns and transgenic constructs to test predictions of the mechanisms regulating silencer activity. Specific Aim 4. GENETIC SCREENS TO IDENTIFY GSC AND CB DIFFERENTIATION FACTORS. Preliminary results support two genetic approaches to identify new GSC and CB differentiation factors. Gene misexpression from P-element insertions can identify genes that disrupt GSC or CB fates when expressed from a strong germ cell promoter. A "sensitized" bam genotype can identify genes that can reduce (E(bam) or increase (Su(bam) bam activity when made heterozygous.

描述（由申请人提供）：同时自我更新和不对称细胞分裂是干细胞的标志。我们现在可以提供一个机制，果蝇的生殖干细胞如何完成这一壮举。干细胞龛中的Dpp信号传导阻断了干细胞中关键的成囊细胞分化因子bam的转录。然而，目前尚不清楚为什么成囊细胞也不响应Dpp信号。这里提出的工作目标是寻求一个更深入和机械的 理解额外的小生境信号，可能解释干细胞和成囊细胞的差异反应。 具体目标1。维持生殖系干细胞（GSC）的机制。确定多种GSC维持因子的作用，使用开发的工具来测定BAM转录激活和操纵DPP信号水平。确定其他小生境信号通路是否通过dpp信号或独立于dpp信号起作用。具体目标2。驱动成囊细胞（CB）分化的机制。由初步结果产生的检验假设-前CB表达dpp信号传导拮抗剂。确定的身份、作用时间和监管 拮抗剂具体目标3。BAM基因沉默机制的分子生物学。充分表征沉默机制中涉及的顺式活性元件和反式作用因子。测试如果Schnurri工程与疯狂淬火巴姆转录。实验方法采用有丝分裂克隆测试shn与bam表达模式和转基因构建体的相关性，以测试沉默子活性调节机制的预测。具体目标4。鉴定GSC和CB分化因子的遗传筛选。 初步结果支持两种遗传方法，以确定新的GSC和CB分化因子。来自P元件插入的基因错误表达可以鉴定当从强生殖细胞启动子表达时破坏GSC或CB命运的基因。“致敏的”bam基因型可以鉴定当杂合时可以降低（E（bam））或增加（Su（bam））bam活性的基因。