title: Testicular Dnmt3 expression and global DNA methylation are down-regulated by gonadotropin releasing hormones in the ricefield eel Monopterus albus.
abstract: In vertebrates, DNA methyltransferase 3 (Dnmt3) homologues are responsible for de novo DNA methylation and play important roles in germ cell development. In the present study, four dnmt3 genes, dnmt3aa, dnmt3ab, dnmt3ba and dnmt3bb.1, were identified in ricefield eels. Real-time quantitative PCR analysis showed that all four dnmt3 mRNAs were detected broadly in tissues examined, with testicular expression at relatively high levels. In the testis, immunostaining for all four Dnmt3 forms was mainly localized to spermatocytes, which also contained highly methylated DNA. All three forms of Gonadotropin-releasing hormone (Gnrh) in the ricefield eel were shown to decrease the expression of dnmt3 genes in the in vitro incubated testicular fragments through cAMP and IP3/Ca2+pathways. Moreover, in vivo treatment of male fish with three forms of Gnrh decreased significantly the testicular Dnmt3 expression at both mRNA and protein levels, and the global DNA methylation levels. These results suggest that the expression of Dnmt3 and global DNA methylation in the testis of ricefield eels are potentially down-regulated by Gnrh, and reveal a novel regulatory mechanism of testicular Dnmt3 expression in vertebrates.
authors.affiliation: Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Yize
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Xin
authors.initials: X
authors.lastname: Sun
authors.affiliation: Biology Department, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, P. R. China.|Biology Department, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Weimin
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000818:Animals; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000096:biosynthesis*; D019175:DNA Methylation; D015536:Down-Regulation; D004524:Eels; D020869:Gene Expression Profiling; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D008297:Male; D060888:Real-Time Polymerase Chain Reaction; D013737:Testis / Q000201:enzymology*
chemical_list: D007987:Gonadotropin-Releasing Hormone; D004248:DNA (Cytosine-5-)-Methyltransferases