Clusterin Expression In Human Male Reproductive System Research

Part I Presence, localization, and origin of clusterin innormal human spermatozoaPurpose Clusterin in mammalian semen is a secretory form of clusterin(sCLU) with the heterodimeric structure. It is secreted by the epididymis and seminalvesicle. It is generally agreed that clusterin mainly exists on the surface of abnormalspermatozoa and is implicated in decreased sperm motility, sperm aggregation andinfertility. However, few studies observe clusterin in normal spermatozoa, which ispresumed to be a novel form. Up to now, the systematical information about thepresence, localization, origin and function of clusterin in normal human spermatozoahas yet not been established. The aim of our current study is to systematicallyresearch clusterin in normal human spermatozoa.Methods We detected the presence of clusterin via western blot, explored thelocalization of clusterin using immunofluorescence, and investigated the origin anddistribution of clusterin in human testis by western blot and immunohistochemistry.Results We found native clusterin in the inner plasma membrane of normalhuman spermatozoa. It was derived from the testis and showed similar molecularweight and heterodimeric structure compared with sCLU in semen and on the surfaceof abnormal spermatozoa.Conclusion Clusterin in normal spermatozoa should be self-synthesizedduring the later stage of spermatogenesis. The different localization and originsuggested that the clusterin observed by us may be a novel form compared withconventional sCLU on the surface of abnormal spermatozoa. Part II Expression of clusterin in the spermatozoa ofidiopathic asthenozoospermic menPurpose Asthenozoospermia, or low sperm motility, is a common cause ofhuman male infertility. Social and family dilemmas of infertility, especially indeveloping and under developed communities are devastating. The purpose of thisstudy is to investigate the expression of clusterin in idiopathic asthenozoospermia.Methods We separated and purified the ejaculated sperm from22idiopathicasthenozoospermia patients and24normozoospermic men by Percoll discontinuousdensity gradients，and detected the distribution and the expressions of clusterinmRNA and clusterin protein by Real-Time PCR and Western blot separately.Results Real-Time PCR revealed that the expression of clusterin mRNA wassignificantly lower in the sperm of the idiopathic asthenozoospermia patients than inthose of the normozoospermic men (0.11±0.07vs0.98±0.26，t=9.15，P＜0.001), andWestern blot confirmed the results of RT-PCR (0.66±0.21vs1.44±0.38，t=6.29，P＜0.05).Conclusion The expression of clusterin is significantly decreased in theejaculated sperm of idiopathic asthenozoospermia patients, which might be one of thecauses of idiopathic asthenozoospermia．...