MAEL啟動子過度甲基化和睪丸內表現量減少和人類造精功能障礙的相關性
鄭裕生1、陳幸儀1、黃詩凱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 promoter hypermethylation and low expression in human testes are associated with spermatogenic failure
Yu-Sheng Cheng1, Sin-Yi Chen1, Shi-Kae Wee1, Yung-Ming Lin1, Shih-Chieh Lin2
Department of Urology, National Cheng Kung University Hospital1; The Institute of Basic Medical Sciences2, College of Medicine, National Cheng Kung University, Tainan, Taiwan
Objective:
Mouse maelstrom was known to participate in the piRNA-mediated defense system to protect the germline from retrotransposons. The male MAEL knockout mice are sterile with small testicles and meiotic arrest. Previously, we reported that the aberrant methylation of MAEL promoter might contribute to one of the causes of spermatogenic failure in infertile men. In this study, we focused on investigating the MAEL expression profile in human testes and spermatozoa in infertile men.
Materials and methods:
This study was approved by the Institutional Review Board of the National Cheng Kung University Hospital, Tainan, Taiwan (A-ER-102-432). There are 26 CpGs in our predicted MAEL promoter region (-131 to +177, TSS=1), which has been determined by whole-genome methylation array. The methylation levels of the MAEL promoter region were investigated by pyrosequencing technology. The protein and mRNA transcript levels of MAEL in the testes of azoospermic men were determined by immunohistochemistry and quantitative real-time-PCR. MAEL in human spermatozoa were investigated by western blotting and immunofluorescence staining. The significance was set at P < 0.05.
Results:
Twenty-six CpGs (-131 to +177, TSS=1) of the MAEL gene showed significantly higher methylation levels in HS group compared to NR group. In the human testes, the MAEL protein was expressed mainly in secondary spermatocyte, spermatid, and spermatozoa. We reported significantly lower expression of MAEL in human testes diagnosed with HS with NOA. Moreover, the MAEL transcript levels were significantly lower in patients with hypospermatogenesis (HS) than normal spermatogenesis(NS).
Conclusions:
Our study provides evidence that MAEL promoter hypermethylation and low expression in human testes are associated with spermatogenic failure.