男性不孕症病患的睪丸和精蟲內的MAEL基因表現

鄭裕生¹、陳幸儀¹、林永明¹、林世杰²

國立成功大學醫學院附設醫院泌尿部¹ 國立成功大學醫學院基礎醫學研究所²

MAEL gene expression in testes and ejaculated sperms of infertile men

 Yu-Sheng Cheng¹, Sin-Yi Chen¹, Yung-Ming Lin¹, Shih-Chieh Lin²

Department of Urology, National Cheng Kung University Hospital ¹; The Institute of Basic Medical Sciences², College of Medicine, National Cheng Kung University, Tainan, Taiwan

Objective:

MAEL was known to participate in the piRNA-mediated defense system to protect the germline from retrotransposons. We previously reported that the MAEL promoter's aberrant methylation might contribute to one of the causes of spermatogenic failure in infertile men. However, there is no report for MAEL expression in human testes or sperm. Thus, this study focused on determining the MAEL expression in human testes and spermatozoa in infertile men.

Materials and methods:

The Institutional Review Board approved this study of the National Cheng Kung University Hospital, Tainan, Taiwan (A-ER-102-432). The protein levels of MAEL in azoospermic men's testes with four different histopathologies (normal spermatogenesis; hypospermatogenesis, meiotic arrest; Sertoli cell-only syndrome) were determined and compared by immunohistochemistry. MAEL in human spermatozoa was investigated by western blotting and immunofluorescence staining. Furthermore, we compared the MAEL protein in the human ejaculated sperm of normospermia versus OAT. The significance was set at P < 0.05.

 Results:

In the human testes, the MAEL protein is expressed mainly in secondary spermatocytes, spermatids, and spermatozoa. We reported significantly lower expression of MAEL in human testes diagnosed with hypospermatogenesis compared to normospermatogenesis. No staining is observed in the testicular samples from patients with maturation arrest at the spermatocyte stage and Sertoli cell-only syndrome. Furthermore, MAEL protein is detected in the mid-piece and tail of sperm by immunofluorescence staining. Western blot analysis further confirmed MAEL proteins in human ejaculated sperm. Moreover, significantly decreased MAEL has been noted in ejaculated sperm of the OAT group compared to the normospermia group.

 Conclusions:

Our study demonstrated that MAEL has essential roles in both spermatogenesis and spermiogenesis. Loss or decreased expression of MAEL may be responsible for one of the causes of male infertility.