DNA Damage Response Pathways in Meiotic Sex Chromosome Inactivation

减数分裂性染色体失活中的 DNA 损伤反应途径

• 批准号: 9235361
• 负责人: Satoshi Namekawa
• 金额: $ 46.8万
• 依托单位: CINCINNATI CHILDRENS HOSP MED CTR
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2021-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9235361
• 关键词: Address; Binding; Biological; Biological Assay; Chromatin; Chromatin Structure; Chromosomes; Congenital Abnormality; Coupled; Cytosine; DNA; DNA Damage; DNA Methylation; Data; Defect; Development; Embryonic Development; Enzymes; Epigenetic Process; Event; Exhibits; Fertility; Fluorescence Recovery After Photobleaching; Gamma-H2AX; Gene Expression; Gene Silencing; Genes; Genomics; Grant; Histones; Infertility; Knock-out; Knockout Mice; Link; Male Infertility; Mediating; Meiosis; Modeling; Molecular; Mus; Nucleosomes; Outcome Study; Pachytene Stage; Pathway interactions; Phase; Phosphorylation; Polycomb; Process; Proteins; Public Health; Publishing; Reaction; Recruitment Activity; Reproduction; Research; Role; Sex Behavior; Sex Chromosomes; Signal Transduction; Spermatocytes; Spermatogenesis; Testing; Variant; bisulfite sequencing; demethylation; histone modification; human male; male; mutant; next generation; novel; response; sperm cell; whole genome

ABSTRACT The objective of this project is to elucidate the regulatory mechanisms and biological significance of the epigenetic programming of the sex chromosomes in the male germline. During male meiosis, unsynapsed sex chromosomes are epigenetically silenced in a process called meiotic sex chromosome inactivation (MSCI), which is necessary for spermatogenesis. During the term of the previous grant, we elucidated the underlying mechanisms of MSCI and demonstrated the role of DNA damage response (DDR) factors as essential regulators. Establishment of MSCI requires phosphorylation of the histone variant H2AX (γH2AX) to spread from the axes to the chromosome-wide domain of the sex chromosomes. This process is directed by MDC1, a binding partner of γH2AX, at the onset of the pachytene stage. Downstream of MDC1, SCML2, a germline- specific Polycomb protein, is recruited to γH2AX-containing nucleosomes and required for epigenetic programming. During the last project period, we unexpectedly found that initiation of MSCI is tightly coupled to active DNA demethylation. Initially the DNA demethylation is directed by MDC1 and precedes the establishment of silent histone modifications. In this renewal application, we will test the central hypothesis that the DDR pathway regulates active DNA demethylation, enabling the epigenetic programming of sex chromosomes necessary for male reproduction. While DNA methylation is generally associated with gene silencing, we propose that DNA demethylation is linked to gene silencing in MSCI. Our data suggest that demethylation in MSCI involves two major phases: the initial phase is mediated by the DDR pathway at the early pachytene stage (Aim 1) and the later phase is mediated by SCML2 downstream of the DDR at the mid- pachytene stage (Aim 2). This study will establish a novel link between DDR signaling and active DNA demethylation, and will further elucidate the biological significance of the epigenetic programming of the sex chromosomes, which is essential for male reproduction.

抽象的 该项目的目的是阐明规律性机制和生物学意义 男性种系中性染色体的表观遗传编程。 染色体在称为减数分裂性染色体无效的过程中表观遗传沉默（MSCI） 这是精子发生所必需的。 MSCI的机制并证明了DNA损伤响应（DDR）因子作为必不可少的作用 监管机构的建立需要组蛋白变体H2AX（γH2AX）的磷酸化 从轴到性染色体的全染色体域。 γH2AX的结合伴侣，在Pachytene阶段开始时。 特异性多蛋白蛋白，募集到含γH2AX的核小体中，并需要表观遗传学 编程。在最后一个项目期间，我们意外地发现MSCI的开始 活性DNA脱甲基化。 在此续签应用中建立无声的组蛋白修改，我们将测试该中心。 DDR途径调节主动DNA脱甲基化，使性别的表观遗传学计划 男性繁殖所需的染色体。 沉默，我们建议DNA脱甲基与MSCI中的基因沉默有关。 MSCI中的去甲基化涉及两个主要阶段：初始阶段是由DDR途径介导的 早期的Pachytene阶段（AIM 1）和后期由DDR下游的SCML2介导 Pachytene阶段（AIM 2）。 脱甲基化，并将进一步阐明性别表观遗传编程的生物学意义 染色体，这对于男性繁殖至关重要。