E3 ligase KLHL10蛋白在精子变形中功能及机制研究

精子变形是精子发生过程中的重要步骤，并被精密调控。负责蛋白质降解的泛素-蛋白酶体途径在精子发生中的功能和机制已有研究，但其在精子变形中的机制，尤其是热应激时，研究甚少。本项目前期研究发现KLHL10蛋白是一个保守的变形精子特异表达的E3 ligase；果蝇KLHL10缺失导致雄性不育、变形精子核浓缩异常；有趣的是，热应激时Klhl10杂合突变生育力快速下降、成熟精子核形态异常，而常温时无此表型；机制研究发现果蝇KLHL10促进热激蛋白的降解。据此，提出科学假说：KLHL10可能通过促进热激蛋白的泛素化降解来保护变形精子的核变形。为了验证这一功能和机制的进化保守性，本项目拟以果蝇和小鼠模型阐明KLHL10在变形精子中核浓缩变形的功能，以及热应激时KLHL10保护变形精子核变形的分子机制，同时探究KLHL10与男性不育疾病的相关性，为临床男性不育的发病机制、诊断和治疗提供新的方向。

Spermiogenesis is one of the key steps of spermatogenesis and need to be precisely regulated. The roles of the ubiquitin-proteasome pathway during spermatogenesis have been addressed, however, their functions and mechanisms in regulating spermatid nuclear deformation, especially under heat-stress, require further characterized. Our previous data showed that KLHL10 protein, a conserved E3 ligase, was expressed specifically in elongating spermatids in Drosophila, mouse, and human testes. Flies missing KLHL10 resulted in male sterility with defects of spermatid nuclear condensation. Notable, under heat stress, Klhl10 heterozygous mutant flies displayed a marked decrease in male fecundity and increase of defective sperm nuclear morphology in seminal vesicle, while these phenotypes did not occur under normal temperature. Furthermore, we found that fly KLHL10 interacted with heat shock proteins (HSPs) and promoted their degradation. Hence, we hypothesize that KLHL10 protein may play an evolutionarily conserved role in ensuring the sperm nuclear condensation and deformation during spermiogenesis via promoting the ubiquitination and degradation of HSPs. To validate this hypothesis, we will 1) investigate the function of KLHL10 protein in spermatid nuclear condensation and shaping by characterizing fly and mouse knockout models for their defects in spermiogenesis, and 2) explore the molecular mechanism of KLHL10 in protection against heat stress-induced nuclear deformation defects. We will also estimate the relationship between KLHL10 gene and clinical male infertility diseases, which may provide new insights into the pathogenesis, diagnosis, and treatment of clinical male infertility diseases.