CREB1调控BRCA1介导的同源重组修复在昼夜节律紊乱导致精子DNA损伤中的作用及机制研究

Sperm DNA damage is one of the important reasons for the decline of male fertility. In our previous study, we found that the DNA double-strand breaks in the sperm of shift workers increased than that of the control group, suggesting that circadian rhythm disorder may be related to double-stranded sperm DNA damage. However, the specific mechanism is unclear. By establishing the circadian rhythm disorder model in mice, we found that the homologous recombination repair pathway in testicular tissue was inhibited and the chromosome recombination rate was decreased. Preliminary evidence showed that Brca1, a key factor on the upstream of this pathway, was regulated by the circadian clock gene Creb1, and the expressions of both Creb1 and Brca1 were inhibited in mice model of circadian rhythm disorder. Therefore, we proposed that circadian rhythm disorder may inhibit Brca1 expression by down-regulating Creb1, and then inhibit homologous recombination repair function, thus aggravating the double-strand breakage of sperm DNA. In this study, we will analyze the DNA strand breaking effect caused by circadian rhythm disorders by animal and cell experiments, and study the roles of Creb1 and Brca1 in homologous recombination repair inhibition and sperm DNA strand breaking caused by circadian rhythm disorders. This study will clarify the regulatory mechanism of Creb1 on Brca1. We will also verify these results in human semen samples and testicular tissues. This project will help to reveal the molecular mechanism of sperm DNA damage caused by circadian rhythm disorder and provide a reference for the development of protective strategies.

精子DNA链断裂损伤是男性生育力下降的重要原因。我们前期发现倒班男性精子DNA双链断裂增多，提示昼夜节律紊乱可能与DNA双链断裂有关，但具体机制不明。通过建立小鼠昼夜节律紊乱模型，我们发现其睾丸组织中同源重组修复通路受到抑制，染色体重组率降低。初步证据显示该通路上游的关键因子Brca1受到生物钟基因Creb1调控，且节律紊乱模型中Creb1和Brca1表达都受到抑制。因此我们提出：昼夜节律紊乱可能通过下调Creb1调控Brca1表达，抑制同源重组修复功能，从而加重精子DNA双链断裂。本研究拟利用动物和细胞实验分析昼夜节律紊乱导致的DNA链断裂效应，研究Creb1和Brca1在昼夜节律紊乱导致的同源重组修复抑制及精子DNA链断裂中的作用，阐明Creb1对Brca1的调控机制；并在人类精子和睾丸组织中加以验证。本项目有助于揭示昼夜节律紊乱致精子DNA损伤的分子机制，为防护策略的开发提供参考。

精子遗传损伤是现代男性常见的精液异常，也是导致男性生育能力下降的重要原因。其中DNA链断裂是较为严重的遗传损伤形式。倒班工作是现代社会常见的职业暴露。倒班工作的主要特点是由于工作时间的不断变化，使人体昼夜节律紊乱，进而导致各种损害效应；但其对精子DNA损伤的影响却缺乏研究。我们前期在社区人群中研究发现从事倒班工作的男性精子DNA双链断裂程度显著高于不从事倒班的男性。本研究中我们通过建立小鼠昼夜节律紊乱模型，发现小鼠精子DNA双链断裂损伤增加，其睾丸组织中同源重组修复通路受到抑制。转录组测序发现其同源重组修复通路发生显著变化，该通路上游的关键因子BRCA1及生物钟基因CREB1表达降低。进一步发现CREB1通过调控BRCA1启动子活性进而促进基因转录，在精母细胞中敲低CREB1表达抑制了BRCA1的表达及同源重组修复能力，促进H2O2诱导的细胞损伤。同样，敲低BRCA1也抑制同源重组修复，促进H2O2诱导DNA损伤的发生。并且，我们利用数字PCR技术检测了人精子RNA中CREB1和BRCA1的表达，发现CREB1与BRCA1表达存在显著正相关；进一步分析发现，CREB1和BRCA1的表达在高DFI样本降低，且表达水平与DFI呈负相关。本项目揭示了昼夜节律紊乱导致的精子DNA链断裂效应，阐明CREB1对BRCA1的调控及在昼夜节律紊乱导致的同源重组修复抑制及精子DNA损伤中的作用，可为相关防护策略的制定提供参考。

内容获取失败，请点击重试