Regulation of Spermatocyte Transcription by Testis TAFs

睾丸 TAF 对精母细胞转录的调节

• 批准号: 8387787
• 负责人: MARGARET T FULLER
• 金额: $ 30.57万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8387787
• 关键词: Address; Binding; Biochemical; Cell Cycle Progression; Cell Differentiation process; Cell Lineage; Cell Nucleolus; Cells; Chromatin; Complex; Deubiquitinating Enzyme; Development; Drosophila genus; Embryo; Failure; Fingers; Funding; Gametogenesis; Gene Targeting; Genes; Genetic; Genetic Screening; Genetic Transcription; Germ Cells; Germ Lines; Goals; Grant; Histones; Homeostasis; Homologous Gene; Infertility; Male Infertility; Malignant Neoplasms; Mammals; Mediator of activation protein; Meiosis; Microarray Analysis; Modeling; Mutation; Nuclear Hormone Receptors; Orphan; PRC1 Protein; Phosphotransferases; Play; Polycomb; Polymerase; Program Development; Proliferating; Promoter Regions; Prophase; Proteins; RNA Interference; Recruitment Activity; Regulation; Regulator Genes; Regulatory Pathway; Repression; Role; SAGA; Spermatids; Spermatocytes; Spermatogenesis; Spermatogonia; Staging; Stem cells; Syndrome; Testing; Testis; Tissues; Trans-Activators; Transcript; Transcription Factor TFIIA; Work; adult stem cell; cell type; cofactor; loss of function; male; man; particle; precursor cell; programs; promoter; public health relevance; transcription factor

DESCRIPTION (provided by applicant): The gene regulatory mechanisms that program cell differentiation from proliferating precursor cells are fundamentally important for development, tissue homeostasis and cancer. Using the dramatic cellular differentiation program of spermatogenesis as a model stem cell lineage, we seek to understand the unique, cell type specific transcription program initiated in the spermatocyte stage that programs cells for terminal differentiation. We discovered that testis-specific TAFs, homologs of components of the general PolII transcription machinery, turn on expression of spermatid differentiation genes, in part by counteracting silencing by the Polycomb machinery in precursor cells. The immediate next challenge is to discover how the testis TAFs act - both directly at promoters to activate robust expression of terminal differentiation genes and in the spermatocyte nucleolus by sequestering the Polycomb transcriptional silencing complex. We will test whether the tTAFs form a testis-specific SAGA-like complex that recruits a histone deubiquitinating enzyme to promoter proximal stalled polymerases, allowing elongation of target transcripts, or instead act in a TFIID-like complex with TBP. We will investigate the role of candidate cofactors that may act with the tTAFs we have identified in a pilot RNAi screen, the mediator subunit Med27 and the orphan nuclear hormone receptor Hr51. Because the tTAFs play such a key role, the mechanisms that program the exquisitely cell type and stage specific expression of the tTAFs themselves are central for understanding the developmental regulatory pathway for cell differentiation. We will investigate the role and mode of action of the BTB-Zn finger transcriptional regulator lola, required for expression of tTAFs in spermatocytes, and its binding partner the Jil1 H3S10 kinase, which is required, like lola, for proper meiotic cell cycle progression and spermatid differentiation. In addition, in a directed genetic screen, we will test candidate transcription regulators expressed at the switch from spermatogonia to spermatocyte to identify additional cofactors that act with the tTAFs and elucidate the regulatory machinery that controls tTAF expression. Our work on the mechanism of action and mode of regulation of the tTAFs in the Drosophila male germ line may provide a paradigm for understanding how development programs cell-type specific terminal differentiation by counteracting repression by the PcG at specific target genes. In addition, understanding the mode of action of the meiotic arrest genes of Drosophila may illuminate mechanisms underlying meiosis I maturation arrest infertility in man.

描述（由申请人提供）：编程从增殖前体细胞分化的基因调控机制对于发育、组织稳态和癌症至关重要。使用精子发生的戏剧性细胞分化程序作为干细胞谱系模型，我们试图了解在精母细胞阶段启动的独特的、细胞类型特异性的转录程序，该程序对细胞进行最终分化。我们发现，睾丸特异性 TAF（一般 PolII 转录机制组件的同源物）可以部分通过抵消前体细胞中 Polycomb 机制的沉默来开启精子细胞分化基因的表达。下一个挑战是发现睾丸 TAF 如何发挥作用 - 直接作用于启动子以激活终末分化基因的稳健表达，并通过隔离 Polycomb 转录沉默复合物在精母细胞核仁中发挥作用。我们将测试 tTAF 是否形成睾丸特异性 SAGA 样复合物，该复合物招募组蛋白去泛素化酶来启动近端停滞聚合酶，从而允许目标转录本延伸，或者与 TBP 一起在 TFIID 样复合物中发挥作用。我们将研究可能与我们在试点 RNAi 筛选中鉴定出的 tTAF、介质亚基 Med27 和孤儿核激素受体 Hr51 相互作用的候选辅助因子的作用。由于 tTAF 发挥着如此关键的作用，因此对 tTAF 本身的精细细胞类型和阶段特异性表达进行编程的机制对于理解细胞分化的发育调控途径至关重要。我们将研究精母细胞中 tTAF 表达所需的 BTB-Zn 指转录调节因子 lola 及其结合伴侣 Jil1 H3S10 激酶的作用和作用方式，该激酶与 lola 一样，是适当的减数分裂细胞周期进程和精子细胞分化所必需的。此外，在定向遗传筛选中，我们将测试从精原细胞到精母细胞转换时表达的候选转录调节因子，以确定与 tTAF 相互作用的其他辅助因子，并阐明控制 tTAF 表达的调节机制。我们对果蝇雄性种系中 tTAF 的作用机制和调节模式的研究可能为理解发育如何通过抵消 PcG 对特定靶基因的抑制来编程细胞类型特异性终末分化提供范例。此外，了解果蝇减数分裂停滞基因的作用模式可能会阐明人类减数分裂 I 成熟停滞不育的潜在机制。