Mechanisms that couple irregular development of fetal melanoblasts to premature exhaustion of adult melanocyte stem cells

项目总结 在成年期间维持组织功能，从而抑制组织退化和疾病， 取决于干细胞种群的维持。成体干细胞是表观遗传编程的，并且 胚胎中开始的一系列发育决定的顶峰。宫内环境暴露于 胚胎可能会影响成人和老年疾病，可能部分是通过对干细胞发育的影响 传递给成人干细胞的维持和功能。然而，分子之间的联系 成人的胚胎发育和干细胞功能和表型的长期维持很差 已定义。我们将利用特定血统的组蛋白伴侣基因失活来了解如何 黑素母细胞(Mb)胚胎发育完整性对成人黑素细胞(Mc)干细胞维持的影响 细胞(MCSC)。 组蛋白伴侣Hira将组蛋白变异体H3.3存入活性基因、启动子和增强子。 小鼠胚胎黑素母细胞(MBS)体外和体内实验及单细胞RNA序列分析 类型小鼠和胚胎MBS中缺乏Hira表达的小鼠，我们揭示了Hira在 维持PAX3/Sox10-MITF Mb规范途径。MBS中Hira的灭活耗尽了数量 在早/中期胚胎中MBS的含量。然而，这种胚胎缺陷是通过出生和幼鼠表现出来的 黑素细胞数量正常，只有非常轻微的色素缺陷。尽管如此，在新生儿中 小鼠，Hira基因敲除(KO)黑素细胞显示出更高频率的端粒相关DNA损伤灶， 这表明，Hira基因敲除了MCSC和/或黑素细胞，即使在新生的小鼠身上也存在分子损伤。 事实上，新生Hira KO小鼠的黑素母细胞和黑素细胞对促增殖反应很差 在体外和体内挑战，这些小鼠表现出显著加速的MCSC和黑素细胞耗竭和 成年期头发变白的速度大大加快。基于这些广泛的初步数据，我们将 研究Hira在黑素细胞系分化和发育中的作用，并研究Hira在黑素细胞系中的作用 成年期和老年期胚胎发育异常与成体干细胞枯竭之间的联系。 PAX3/Sox10-MITF信号通路的失调与发育障碍和 黑色素瘤。这些研究确定Hira在PAX3/Sox10-MITF轴中的作用可以促进治疗 防治这些发育和肿瘤疾病的干预措施。此外，完成这些具体的 AIMS将阐述组织特异性干细胞胚胎发育的完整性如何影响维持 这些干细胞在成年期。

PROJECT SUMMARY Maintenance of tissue function during adulthood, and hence suppression of tissue degeneration and disease, depends on maintenance of stem cell populations. Adult stem cells are epigenetically programmed and a culmination of a series of developmental decisions initiated in the embryo. In utero environmental exposures on the embryo can influence adult and late-life disease, likely in part via effects on stem cell development that are transmitted to maintenance and function of stem cells in the adult. However, the molecular links between embryonic development and long-term maintenance of stem cell function and phenotype in adults are poorly defined. We will employ lineage-specific genetic inactivation of a histone chaperone to understand how embryonic developmental integrity of melanoblasts (Mb) impacts on maintenance adult melanocyte (Mc) stem cells (McSC). The histone chaperone HIRA deposits histone variant H3.3 into active genes, promoters and enhancers. Through in vitro and in vivo studies and single cell RNA-seq of mouse embryo melanoblasts (Mbs) from wild type mice and mice lacking expression of HIRA in embryonic Mbs, we have uncovered a role for HIRA in sustaining the PAX3/SOX10-MITF Mb specification pathway. Inactivation of HIRA in Mbs depletes the number of Mbs in early/mid stage embryos. However, this embryonic defect is rescued by birth and young mice exhibit normal numbers of melanocytic cells, and only a very subtle pigmentation defect. Nevertheless, in new-born mice, Hira knock out (KO) melanocytic cells exhibit a higher frequency of telomere-associated DNA damage foci, indicating that Hira knock out McSC and/or melanocytes harbor molecular damage, even in new-born mice. Indeed, melanoblasts and melanocytes from new-born Hira KO mice respond poorly to pro-proliferative challenge in vitro and in vivo, and these mice show marked accelerated McSC and melanocyte depletion and dramatically accelerated hair greying during adulthood. Building on these extensive preliminary data, we will investigate the role of HIRA in differentiation and development of the melanocytic lineage, and investigate the links between abnormal embryonic development and adult stem cell depletion during adulthood and aging. Dysregulation of the PAX3/SOX10-MITF signaling pathway contributes to developmental disorders and melanoma. These studies to define HIRA's role in the PAX3/SOX10-MITF axis can promote therapeutic interventions to combat these developmental and neoplastic disorders. Moreover, completion of these Specific Aims will address how the integrity of embryonic development of tissue specific stem cells impacts maintenance of those stem cells during adulthood.