Regulation of proliferation and differentiation in the male germ line adult stem cell lineage

项目摘要（父项目）： 男性生殖系成体干细胞系增殖和分化的调控 从增殖到分化的转换是胚胎发育和胚胎发育中的关键调节点。 成体干细胞谱系是组织维护和修复的基础。此开关的故障可能导致 癌症的起源我的实验室长期以来一直以果蝇雄性生殖细胞系为模型， 在成体干细胞谱系中调节自我更新、增殖和分化。我们的几条调查线索 最近开始集中研究发育程序性疾病的分子机制， 从有丝分裂增殖到减数分裂和分化开始的过渡，涉及许多分子和 调节这一关键开关的细胞机制。我们发现，RNA结合蛋白参与翻译， 控制和选择性剪接自主地作用于细胞以调节增殖的停止， 分化的进展需要来自相关体细胞支持细胞的通讯。我们发现 在特定的新生转录物被切割形成3'末端的位点中的发育调节开关， 导致产生具有缩短的3 'UTR的新型mRNA同种型，控制了一系列基因的急剧变化。 与增殖的精原细胞相比，在分化的精母细胞中表达的蛋白质。我们发现 染色质的巨大变化打开了2000多个新的启动子，这些启动子具有新的核心序列结构， 当细胞启动精母细胞分化时，新的细胞类型特异性转录程序。一些最早的 在这个分化程序中开启的基因编码染色质相关蛋白， 打开通常隐藏的启动子，从而防止与基因表达相关的基因的大量错误表达。 错误的细胞类型其他转录上调分化开始编码细胞类型特异性翻译 延迟核心G2/M细胞周期机器的产生以编程减数分裂的延长G2期的调节剂 前期在接下来的5年里，我们建议绘制这些流程如何合作，以形成监管 启动电路然后执行从有丝分裂到减数分裂的转换。我们将研究RNA结合 Bam和Bgcn蛋白通过抑制细胞核的表达而触发从有丝分裂到分化的转变。 选择性剪接因子HOW，通过免疫沉淀，然后通过RNA- Seq，并评估它们在体内的功能，包括它们是否与相邻的体细胞支持细胞通讯。 我们将研究如何在蛋白质表达的开关，由于替代3'端切割位点选择新生 转录物是受调节的，并影响分化。我们将研究细胞类型特异性染色质 将它们募集到特定位点的调节因子和蛋白质为分化建立了新的转录程序。 为了阐明发育程序如何重塑细胞周期等基本细胞过程， 分化的专门细胞类型，我们将研究如何细胞类型特异性RNA结合蛋白首先 在减数分裂前期抑制，然后激活细胞周期蛋白B的翻译，以及DAZ同源物Boule如何调节 进入减数分裂阶段。

PROJECT SUMMARY (of Parent Project): Regulation of proliferation and differentiation in the male germ line adult stem cell lineage The switch from proliferation to differentiation is a key regulatory point in both embryonic development and the adult stem cell lineages that underlie tissue maintenance and repair. Failure of this switch may contribute to genesis of cancer. My laboratory has long used the Drosophila male germ line as a model to investigate how self-renewal, proliferation and differentiation are regulated in adult stem cell lineages. Several lines of our inquiry have recently begun to converge on the molecular mechanisms underlying the developmentally programmed transition from mitotic proliferation to onset of meiosis and differentiation, implicating a number of molecular and cellular mechanisms in regulating this critical switch. We find that RNA binding proteins involved in translational control and alternative splicing act cell autonomously to regulate the cessation of proliferation and that progression of differentiation requires communication from associated somatic support cells. We discovered that a developmentally regulated switch in the site at which specific nascent transcripts are cut to form 3’ ends, leading to production of novel mRNA isoforms with shortened 3’UTRs, controls dramatic changes in the suite of proteins expressed in differentiating spermatocytes compared to proliferating spermatogonia. We found that dramatic changes in chromatin open over 2000 new promoters with novel core sequence structure to turn on the new cell type specific transcription program when cells initiate spermatocyte differentiation. Some of the earliest genes turned on in this differentiation program encode chromatin associated proteins that prevent spurious opening of normally cryptic promoters, thus preventing massive misexpression of genes associated with the wrong cell type. Other transcripts upregulated with differentiation onset encode cell type-specific translational regulators that delay production of core G2/M cell cycle machinery to program the extended G2 phase of meiotic prophase. Over the next 5 years, we propose to map how these processes collaborate to form the regulatory circuitry that initiates then executes the switch from mitosis to meiosis. We will investigate how the RNA binding proteins Bam and Bgcn trigger the switch from mitosis to differentiation by repressing expression of the alternative splice factor HOW, identify candidate substrates of HOW by immunoprecipitation followed by RNA- Seq, and assess their function in vivo, including whether they communicate with adjacent somatic support cells. We will investigate how the switch in proteins expressed due to alternative 3’ end cut site selection on nascent transcripts is regulated and influences differentiation. We will investigate how cell-type specific chromatin regulators and proteins that recruit them to specific loci set up the new transcription program for differentiation. To elucidate how the developmental program remodels fundamental cellular processes like the cell cycle to set up differentiation of specialized cell types, we will investigate how cell-type specific RNA binding proteins first repress, then activate translation of cyclin B during meiotic prophase and how the DAZ homolog Boule regulates progression into the meiotic divisions.