P granules and control of germ cell development

摘要 生殖细胞执行多细胞生物的生殖功能，正常生殖细胞 人类的发展确保了物种的生存。生殖颗粒是生殖细胞中保守的细胞质细胞器 细胞，对这些细胞的存活、分化和功能至关重要。胚粒成分突变 或其表达的丧失导致模式生物体的不育，并与人类的不育有关。通过 相反，体细胞中生殖颗粒成分的不适当表达与肿瘤的发生有关， 人类许多RNA结合蛋白和发育调控的mRNA在生殖细胞中富集， 颗粒，导致假设这些细胞器的功能，在调节mRNA的稳定性或翻译 活性;然而，这些细胞器的分子功能仍然不确定。 线虫C. elegans已被用于分析生殖细胞中mRNA的翻译控制 发展通过关注促进RNA结合调节蛋白FBF-2定位的辅因子， 生殖干细胞中的生殖颗粒（在这个物种中称为P颗粒），我们已经产生了一组 这些创新工具将解决P颗粒调节FBF-2活性的关键机制。通过 整合遗传，分子，生物化学和成像为基础的方法，我们将：1）确定如何FBF-2 与对P颗粒定位重要的辅因子蛋白DLC-1的相互作用影响翻译抑制 2）明确P颗粒重塑的机制，在FBF-2的作用下特异性降解FBF-2。 当干细胞从增殖过渡到分化时减数分裂的开始; 3）确定DLC-1的作用 与核心P颗粒成分的结合在调节胚胎P颗粒的稳定性和募集 瞬时P颗粒组分如FBF-2转化为成体生殖系P颗粒。我们的实验系统是 准备揭示特定的分子机制，介导胚芽颗粒之间的相互作用， 翻译调节由于胚粒是一种保守的细胞器， 保守的调节蛋白，在这个模型系统的研究将提供关键的洞察的原因， 人类的不孕症

Abstract Germ cells carry out the reproductive function of multicellular organisms, and normal germ cell development ensures survival of the species. Germ granules are conserved cytoplasmic organelles of germ cells, essential for survival, differentiation, and function of these cells. Mutations in germ granule components or loss of their expression lead to infertility in model organisms and are associated with infertility in humans. By contrast, inappropriate expression of germ granule components in somatic cells is linked to carcinogenesis in humans. Many RNA-binding proteins and developmentally regulated mRNAs are found enriched in germ granules, leading to a hypothesis that these organelles function in regulation of mRNA stability or translational activity; yet, the molecular function of these organelles is still undefined. The nematode C. elegans has been instrumental for analysis of mRNA translational control in germline development. Through focusing on cofactors that promote localization of RNA-binding regulatory protein FBF-2 to germ granules (called P granules in this species) in germline stem cells we have generated a set of innovative tools that will address key mechanisms through which P granules regulate FBF-2 activity. By integrating genetic, molecular, biochemical and imaging-based approaches, we will: 1) Determine how FBF-2 interaction with a cofactor protein DLC-1 important for P granule localization impacts translational repression exerted by FBF-2; 2) Define the mechanisms of P granule remodeling that specifically degrade FBF-2 at the onset of meiosis when stem cells transition from proliferation to differentiation; 3) Determine the role of DLC-1 binding to core P granule components in regulation of stability of embryonic P granules and in recruitment of transient P granule components such as FBF-2 to adult germline P granules. Our experimental system is poised to reveal specific molecular mechanisms mediating the interplay between germ granules and translational regulation. Since germ granules are conserved organelles and our research focuses on conserved regulatory proteins, studies in this model system will provide critical insight into the causes of infertility in humans.