检控蛋白Rad17在小鼠睾丸精子发生过程中的表达及其磷酸化变化

Rad17是细胞周期检控点信号转导过程中的一个关键检控蛋白，在DNA损伤检控和DNA复制检控中具有重要功能。但Rad17在细胞减数分裂中的检控作用还不是很清楚。因细胞减数分裂在睾丸组织中非常活跃，应用Western印迹检测Rad17在不同发育时期的小鼠睾丸组织中的表达及其磷酸化水平，并应用免疫组化的方法检测小鼠睾丸组织不同时期生殖细胞内Rad17的表达变化。结果显示Rad17在小鼠睾丸组织内高表达，而在肝、肾等组织中表达水平较低；Rad17在不同周龄的小鼠睾丸组织中均高水平表达，但在4周龄以后的小鼠睾丸组织中其磷酸化水平明显升高；免疫组化结果显示Rad17在精原细胞、精母细胞的细胞核中高表达，但在成熟精子细胞中消失。这些结果提示Rad17在小鼠睾丸生殖细胞减数分裂过程中也起重要检控作用。

Expression and Phosphorylation of Rad17 Checkpoint Protein during Spermiogenesis in Mouse Testis

Rad17 is one of critical checkpint proteins in cell cycle checkpoint singling pathways and plays vital roles in DNA damage checkpoint and DNA replication checkpoint. However, the role of Rad17 in meiotic checkpoint is poorly understood. Since meiosis is very active in adult testis, we investigated the expression and phosphorylation change of Rad17 in mouse testis at different stages by Western blot analysis, and examined the expression of Rad17 in the germ cells at different meiotic stages in testis by Immunohistochemistry. Our results revealed that Rad17 protein was overexpressed in mouse testis tissues, while other tissues such as liver and kidney expressed much lower Rad17. Although Rad17 expression remained high level in mouse testis at different development stages, the phosphorylation level of Rad17 was significantly increased after four weeks of birth. Immunohis- tochemical analysis indicated that Rad17 protein was present primarily in the nuclei of spermatogonia and spermatocyte, and disappeared in the matured spermatids. These results showed that Rad17 also played an important role in meiotic checkpoint during germline development in testis.