Dynamics of Mitochondrial Inheritance in C. elegans Primordial Germ Cells

项目总结 线粒体是动态的双膜细胞器，包含一个独立的基因组(MtDNA)。每个人 线粒体基因是必不可少的；然而，线粒体DNA在以下情况下的突变率要高得多 与核基因组相比。因此，mtdna突变是最常见的遗传来源之一。 人类的疾病。然而，在线粒体基因组中建立的突变相对较少。 跨越几代人。遗传证据表明，针对突变mtDNA的选择发生在雌性 然而，线粒体DNA选择发生的机制仍然知之甚少。的目标是 这项拟议的研究旨在通过以下方式促进我们对线粒体DNA遗传的理解 研究线虫PGC线粒体遗传的分子和细胞机制， 这为在细胞分辨率下检测线粒体遗传提供了一个出色的模型。 在胚胎发育后期，线虫PGC经历了剧烈的重塑过程，其中大部分细胞 质量和内容将被丢弃。当PGC形成细胞器充满的叶状突起时，PGC重塑， 它们被邻近的内胚层细胞切断并消化。在这个过程中，大多数PGC线粒体质量是 迷路了。我们观察到，线粒体最初定位于PGC叶，但随后有一个子集迁移 在肺叶切除前回到PGCs。这些可能是遗传来的线粒体。我假设 PGC叶的形成和去除是一种机制，通过这种机制， 线粒体/线粒体DNA受到调控，以确保合适的线粒体传递给下一代。这就做 用两种方式来研究这一假设。首先，我将实证地确定哪些线粒体是由 并验证线粒体分裂是PGCs线粒体正确分离所必需的假设。 使用实时成像。(AIM1)。其次，我将确定线虫PGC小叶的形成/移除是否调节 遗传过程中线粒体DNA/线粒体质量。我将测试线粒体DNA选择的两个主要假设，即 线粒体瓶颈和纯化选择，通过量化mtDNA在肺叶切除前后 野生型和线粒体突变株。然后我会检验线粒体的假设 使用线粒体健康的保守标记，功能性驱动PGC叶的线粒体选择 (AIM2)。线粒体突变对胚胎发育和男性/女性有特别严重的影响 由于精子发生缺陷、过早衰老和发育停滞而导致的不育症。我预料到了 我的发现将有助于更深入地理解这些机制，因此对 未来开发人类线粒体疾病和生殖障碍的治疗方法。

PROJECT SUMMARY Mitochondria are dynamic double-membraned organelles that contain an independent genome (mtDNA). Each mitochondrial gene is essential; however, mitochondrial DNA has a substantially higher rate of mutation when compared to the nuclear genome. As a result, mtDNA mutation is one of the most common sources of genetic disease in humans. Nonetheless, relatively few mutations have been established in mitochondrial genomes across generations. Genetic evidence suggests that selection against mutant mtDNAs occurs in the female germline, however, the mechanisms by which mtDNA selection occurs remain poorly understood. The goal of the proposed research is to advance our understanding of mitochondrial DNA inheritance by investigating the molecular and cellular mechanisms of mitochondrial inheritance in C. elegans PGCs, which provide an outstanding model for examining mitochondrial inheritance at cellular resolution. During late embryogenesis, C. elegans PGCs undergo a drastic remodeling process, whereby much of their cell mass and content is discarded. PGC remodeling occurs when PGCs form organelle-filled lobe-like protrusions, which are cut off and digested by adjacent endodermal cells. In the process, most PGC mitochondrial mass is lost. We have observed that mitochondria initially localize into PGC lobes, but a subset subsequently migrates back into PGCs prior to lobe removal. These are presumably the mitochondria that are inherited. I hypothesize that PGC lobe formation and removal is a mechanism whereby the number and/or quality of mitochondria/mtDNAs are regulated to ensure that fit mitochondria are passed on to the next generation. I will approach this hypothesis in two ways. First, I will empirically determine which mitochondria are inherited by PGCs and test the hypothesis that mitochondrial fission is required for proper mitochondrial segregation in PGCs using live imaging. (AIM1). Second, I will determine if C. elegans PGC lobe formation/removal regulates mtDNA/mitochondrial quality during inheritance. I will test the two primary hypotheses of mtDNA selection, the mitochondrial bottleneck and purifying selection, by quantifying mtDNA prior to and following lobe removal in wild type and mitochondrial mutant strains respectively. Then I will test the hypothesis that mitochondrial functionality drives mitochondrial selection in PGC lobes using conserved markers of mitochondrial health (AIM2). Mitochondrial mutations have particularly severe effects on embryonic development and male/female infertility resulting from spermatogenesis defects, premature aging, and developmental arrest. I anticipate that my findings will contribute to a deeper understanding of these mechanisms, and thus, will be essential for developing treatments of human mitochondrial disease and reproductive disorders in the future.