Cell competition in the developing mouse germline

描述(由申请人提供) 摘要：生物体内细胞之间的竞争在社会阿米巴、果蝇和癌症的发生和转移中已被认识到。“赢家”细胞在生长、黏附或存活方面表现出优势，可能会增加个体有机体的整体健康状况。然而，只有生殖细胞之间的竞争才会导致“赢家”特征的直接遗传。由于配子是从原始生殖细胞(PGC)在早期胚胎发育过程中建立起来的，因此在这个细胞谱系中必须发生经历选择和驱动物种进化的可遗传基因突变。我之前证明了生殖系干细胞在基本脊索中的竞争，最近的工作暗示了哺乳动物中的一个平行现象。我们的目标是确定小鼠生殖细胞竞争的基因调控和遗传基础。我们将从三个方面研究小鼠胚胎中PGCs之间的竞争：多能上皮细胞在生殖系中的分配，PGCs向性腺脊的迁移，以及当PGCs开始性别特异性分化时，它们在胚胎性腺中的扩张。为了模拟体内同基因PGC之间的竞争，我们将使用遗传标记策略；将“获胜”的PGC克隆与未纯化或非显性克隆进行比较，将揭示基因表达和表观遗传学差异，这可能为发育中的生殖细胞提供优势。为了通过基因改变来模拟竞争优势，我们将使用7个不同的PGC突变体，这些突变体是我们之前在小鼠胚胎的正向遗传筛查中发现的。我们将使用移植方法在体内将这些PGC耗尽、过剩和迁移表型相互竞争，并询问特定的基因突变如何影响进入种系、迁移和促进配子生物发生的适合性。我们希望从分子上了解PGCs如何与它们的利基相互作用，并提供对细胞选择的基本调控和遗传机制的洞察，这些机制是进化和肿瘤发生的基础。 公共卫生相关性：由于癌症的起源和发展是由于细胞在生存、增殖或迁移方面获得选择性优势而发生的，对细胞竞争机制的研究将确定在肿瘤发展过程中变得不受调控的基因改变、调节或表观遗传变化，并可能有助于癌症诊断或靶向治疗。在辅助生殖技术中，从多能干细胞中区分配子的前景迫在眉睫，了解生殖细胞竞争将有助于揭示体内生殖细胞发育短路的潜在风险和生物学后果。

DESCRIPTION (Provided by the applicant) Abstract: Competition between cells within organisms has been recognized in social amoebae, Drosophila, and the inception and metastasis of cancer. "Winner" cells exhibit advantages in growth, adhesion or survival, putatively increasing the overall fitness of the individual organism. However, only competition among germ cells results in direct inheritance of "winner" traits. As gametes are established during early embryonic development from primordial germ cells (PGCs), heritable genetic mutations that undergo selection and drive evolution of species must occur in this cell lineage. I previously demonstrated germline stem cell competition in a basal chordate and recent work hints at a parallel phenomenon in mammals. Our goal is to determine the gene regulatory and genetic bases for germ cell competition in mice. We will study competition among PGCs in the mouse embryo in three aspects of their development: the allocation of pluripotent epiblast cells to the germline, the migration of PGCs to the gonadal ridges, and the expansion of PGCs in the embryonic gonad as they commence sex-specific differentiation. To model in vivo competition among isogenic PGCs, we will employ genetic marking strategies; comparison of "winning" PGC clones to unpurified or non-dominant ones will reveal gene expression and epigenetic differences that potentially bestow an advantage to developing germ cells. To model competitive advantage by genetic alteration, we will employ 7 different PGC mutants that we previously identified in a forward genetic screen of mouse embryos. We will use transplantation approaches to pit these PGC depletion, overabundance and migration phenotypes against one another in vivo and ask how a particular genetic mutation impacts fitness to enter the germline, migrate, and contribute to gamete biogenesis. We hope to gain a molecular understanding of how PGCs interact with their niches and provide insight into basic regulatory and genetic mechanisms of cellular selection that underlie evolution and tumorogenesis. Public Health Relevance: Since the origin and progression of cancer occurs by cells gaining a selective advantage in survival, proliferation or migration, study of the mechanism of cell competition will identify genetic alterations, regulatory or epigenetic changes that become dysregulated in tumor development and could be useful in cancer diagnosis or targeted for therapy. In assisted reproductive technologies, where the prospect of differentiating gametes from pluripotent stem cells looms on the horizon, understanding germ cell competition will be instrumental to informing the potential risks and biological consequences of short circuiting in vivo germ cell development.