title: Role of multiple microRNAs in the sexually dimorphic expression of Cyp2b9 in mouse liver.
abstract: Mouse cytochrome P450 2b9 (Cyp2b9) is a testosterone 16α-hydroxylase enzyme showing female-specific expression in many inbred mouse strains, including C57BL/6J. Previous studies have recognized that some sex-dependently secreted endogenous modulating factors were involved in the sexually dimorphic expression of Cyp2b9 through transcriptional regulation. In this study, we found evidence that some microRNAs contributed to the sexually biased expression of Cyp2b9 via post-transcriptional regulation. Cyp2b9 was upregulated in livers of hepatocyte-specific Dicer1 knockout mice at 3 weeks. The age-dependent downregulation of Cyp2b9 in the livers of male mice was diminished when Dicer1 was specifically knocked out in hepatocytes. When these data were combined with bioinformatics analysis and microRNA profiles of male and female mice, we found that 18 microRNAs were associated with the sexually dimorphic expression of Cyp2b9, which showed higher expression levels in male C57BL/6J mice when compared with females. Luciferase assays revealed that approximate half of these microRNAs repressed luciferase activity in a reporter system containing the 3'-untranslated region (3'-UTR) of Cyp2b9, and also inhibited Cyp2b9 protein expression. MicroRNA seed region mutation or mutations in putative binding sites of the microRNAs in Cyp2b9 3'-UTR led to the loss of the suppression of luciferase activity. There was also a negative correlation between the levels of these microRNAs and Cyp2b9. Our results suggested that multiple microRNAs participated in the regulation of Cyp2b9 expression, and that the lower expression levels of these microRNAs potentially contributed to the female-specific expression of Cyp2b9 in the livers of C57BL/6J mice.
authors.affiliation: Center for Drug Safety Evaluation and Research, Shanghai Institute of Materia Medica, (X.X., L.M., J.Y., C.F., C.L., M.G., M.L., L.G., X.Q., J.R.), Laboratory of Neural Signal Transduction, Institute of Neuroscience, Chinese Academy of Sciences (Y.W.), Shanghai, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Xie
authors.forename: Lingling
authors.initials: L
authors.lastname: Miao
authors.forename: Jun
authors.initials: J
authors.lastname: Yao
authors.forename: Chenchen
authors.initials: C
authors.lastname: Feng
authors.forename: Chenggang
authors.initials: C
authors.lastname: Li
authors.forename: Man
authors.initials: M
authors.lastname: Gao
authors.forename: Mingxia
authors.initials: M
authors.lastname: Liu
authors.forename: Likun
authors.initials: L
authors.lastname: Gong
authors.forename: Yizheng
authors.initials: Y
authors.lastname: Wang
authors.forename: Xinming
authors.initials: X
authors.lastname: Qi
authors.forename: Jin
authors.initials: J
authors.lastname: Ren
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D000072467:Cytochrome P450 Family 2; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D005260:Female; D022781:Hepatocytes / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism; D012727:Sex Characteristics; D013250:Steroid Hydroxylases / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation / Q000235:genetics
chemical_list: D020413:3' Untranslated Regions; D035683:MicroRNAs; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C121503:Cyp2b9 protein, mouse; D000072467:Cytochrome P450 Family 2; C509781:Dicer1 protein, mouse; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases