Functional Research Of Testis Specific Serine/Thrinine Kinase 5 (TSSK5) Using The Mice Model

Human TSSK5 (Testis specific Serine/threonine Kinase) is the fifith member of testis specific serine/threorine kinase family. It is especially expressed in testis but not any other tissues. In vitro, hTSSK5 phosphorylate transcription factor CREB (cAMP responsive element protein) at Ser-133 site and stimulate CRE transduction pathway.In present work, we investigated biological function of TSSK5 using TSSK5 deletion mice model. We first generated the specific polyclonal antibody of TSSK5 by immuning the rabbit. The antibody indicated that TSSK5 was expressed in the testis exclusively. In the process of mouse testis development, the earliest stage at which TSSK5 was detected was 3 weeks postnatal in various sperm cells, but not in Leydig and Sertoli cell. In spermatogenesis, the highest transcription level of TSSK5 appeared in primary spermatocyte while the highest protein level appeared in post-meiotic haploid rounded sperm cell with granular distribution. In spermiogenesis, TSSK5 also granularlly existed in the cytoplasm but not the nucleus of elongating spermatid. In mature sperm, TSSK5 was expressed on the sperm flagellum. The research for physical and chemical properties of TSSK5 showed that TSSK5 owned kinase activity and autophosphorylation property which was fulfilled through a trans manner. The non-phosphoralytion and phosphoralytion style of TSSK5 co-existed in mouse testis in vivo.Targeted deletion of TSSK5 resulted in serious decreased male fertility due to the abnormal bend of the sperm flagellum, almost disjunction in the connecting site between middle piece and principal piece of sperm flagellum. The bend aberration rate of KO mice increased 8.5 fold than the wide type (77% in mutant mice VS 9% in normal mice). Transmission electron microscopy further showed that the cortex electronic density in the outer dense fibers of the "9+9+2" flagellum structure increased evidently, the axoneme of the connecting site between middle piece and principle piece nearly "collapsed". Sperm movement video showed obvious movement disability. The abnormality of sperm flagellum leaded to serious decreased male fertility to 50% compared to normal mice, but the female was unaffected. All these results indicated that the biological function of TSSK5 was that it influences male fertility by regulating the structure and movement of sperm flagellum.All the results dicribed above are first discovered. Further research for this project will hopefully illuminate the mechanism that TSSK5 regulates spermatogenesis or spermiogenesis. It will provide some new clues to invent some new contraceptives for male or reveal some causes of male infertility.