BMB Rep. 2014; 47(2): 86-91  
Demethylation of CpG islands in the 5' upstream regions mediates the expression of the human testis-specific gene MAGEB16 and its mouse homolog Mageb16
Yunqiang Liu#,*, Meiling Wang#, Siyuan Jiang, Yongjie Lu, Dachang Tao, Yuan Yang, Yongxin Ma & Sizhong Zhang
Department of Medical Genetics and Division of Human Morbid Genomics, State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu 610041, China
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Received: March 21, 2013; Revised: April 23, 2013; Accepted: June 11, 2013; Published online: February 28, 2014.
© Korean Society for Biochemistry and Molecular Biology. All rights reserved.

Tissue-specific gene expression is regulated by epigenetic modification involving trans-acting factors. Here, we identified that the human MAGEB16 gene and its mouse homolog, Mageb16, are only expressed in the testis. To investigate the mechanism governing their expression, the promoter methylation status of these genes was examined in different samples. Two CpG islands (CGIs) in the 5' upstream region of MAGEB16 were highly demethylated in human testes, whereas they were methylated in cells without MAGEB16 expression. Similarly, the CGI in Mageb16 was hypomethylated in mouse testes but hypermethylated in other tissues and cells without Mageb16 expression. Additionally, the expression of these genes could be activated by treatment with the demethylation agent 5'-aza-2'- deoxycytidine (5'-aza-CdR). Luciferase assays revealed that both gene promoter activities were inhibited by methylation of the CGI regions. Therefore, we propose that the testis-specific expression of MAGEB16 and Mageb16 is regulated by the methylation status of their promoter regions.
Keywords: CpG island, DNA demethylation, MAGEB16, Mageb16, Testis-specific expression

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