精子形成过程中组蛋白超乙酰化调控的分子机制研究

During mammalian spermiogenesis, there is an important histone hyperacetylation process, which is requisite for the later histone replacement and chromatin condensation. However, the histone acetylase (HAT) that responsible for this process has not been determined yet. In the previous study, we treated mouse primary spermatids in vitro by histone acetylase inhibitor Curcumin. As expected, the acetylated histone level was dramatically downregulated by Curcumin treatment. In addition, we found the transcription in spermatids ceased in advance, the apoptosis was increased, and the dynamics of various chromatin associated factors was disturbed. Particulariy, we detected the decreased expression of Cdyl gene, which encoding a spermatogenic-specific HAT. Based on these results, we supposed Cdyl protein involved in the histone hyperacetylation in spermatids, while Curcumin impaired the spermiogenesis mainly through its inhibiting effect on Cdyl. In present study, we will further evaluate the Curcumin effects on in vivo spermatogenesis and male fertility, as well as create the germline conditional knockout model of Cdyl, in order to elucidate the above hypothesis. This research will deepen our knowledge of regulation in mammalian spermatogenesis.

组蛋白超乙酰化现象是哺乳动物精子形成过程中重要的特征性事件，然而，负责催化这一过程的组蛋白乙酰基转移酶（HAT）至今仍未被确定。本项目组在前期研究中发现，用组蛋白乙酰基转移酶抑制剂姜黄素（Curcumin）处理小鼠单倍体精子细胞，可以显著地下调精子细胞中组蛋白乙酰化水平，精子细胞中的转录提前终止、细胞凋亡上升，而变形过程出现异常。在此过程中，我们检测到一种生精细胞特异性的HAT蛋白Cdyl的表达受到抑制。因此我们推测，Cdyl就是负责催化精子细胞中组蛋白超乙酰化的酶，姜黄素对Cdyl的抑制是其影响精子形成的主要分子机制。在本项目中，我们将通过体内实验验证姜黄素对小鼠精子发生及生育力的影响，通过构建生殖细胞条件性敲除Cdyl基因的小鼠模型来明确Cdyl蛋白在精子形成中的作用。本项目将加深对精子发生调控机制的理解，并为Y染色体微缺失导致男性不育的致病机制提供新的实验依据。

Y染色体微缺失是男性不育的常见遗传学病因之一。CDY基因是Y染色体微缺失热点区域，是导致男性不育的候选基因之一，然而，CDY蛋白在精子发生中的作用仍未被完全解析。小鼠Cdyl基因是人类CDY基因同源物。在本研究中，我们成功地构建了Cdyl基因生殖系条件性敲除（Cdyl-cKO）小鼠模型。此类雄鼠表现为渐进性不育，具体表型包括精原细胞增殖、分化异常，以及精子形态及活力的异常，可以代表一部分Y染色体微缺失患者的临床症状。通过深入研究，我们证实，Cdyl-cKO小鼠生精细胞中，多种组蛋白甲基化及乙酰化修饰出现异常，提示Cdyl蛋白在精子发生过程中发挥重要的表观调控作用。RNAseq实验证实，Cdyl-cKO小鼠睾丸中转录谱异常，从而导致了一系列复杂的生精障碍表型。本研究初步揭示了CDY(L)蛋白在精子发生中的作用，并为Y染色体微缺失相关的男性不育的诊断治疗提供了新的理论依据。