title: miR-93/Sp7 function loop mediates osteoblast mineralization.
abstract: microRNAs (miRNAs) play pivotal roles in osteoblast differentiation. However, the mechanisms of miRNAs regulating osteoblast mineralization still need further investigation. Here, we performed miRNA profiling and identified that miR-93 was the most significantly downregulated miRNA during osteoblast mineralization. Overexpression of miR-93 in cultured primary mouse osteoblasts attenuated osteoblast mineralization. Expression of the Sp7 transcription factor 7 (Sp7, Osterix), a zinc finger transcription factor and critical regulator of osteoblast mineralization, was found to be inversely correlated with miR-93. Then Sp7 was confirmed to be a target of miR-93. Overexpression of miR-93 in cultured osteoblasts reduced Sp7 protein expression without affecting its mRNA level. Luciferase reporter assay showed that miR-93 directly targeted Sp7 by specifically binding to the target coding sequence region (CDS) of Sp7. Experiments such as electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP), and promoter luciferase reporter assay confirmed that Sp7 bound to the promoter of miR-93. Furthermore, overexpression of Sp7 reduced miR-93 transcription, whereas blocking the expression of Sp7 promoted miR-93 transcription. Our study showed that miR-93 was an important regulator in osteoblast mineralization and miR-93 carried out its function through a novel miR-93/Sp7 regulatory feedback loop. Our findings provide new insights into the roles of miRNAs in osteoblast mineralization.
authors.affiliation: Institute of Endocrinology and Metabolism, The Second Xiangya Hospital of Central South University, 139# Middle Renmin Road, Changsha, Hunan 410011, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.forename: Peng
authors.initials: P
authors.lastname: Cheng
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: He
authors.forename: Gen-Qing
authors.initials: GQ
authors.lastname: Xie
authors.forename: Hou-De
authors.initials: HD
authors.lastname: Zhou
authors.forename: Hui
authors.initials: H
authors.lastname: Xie
authors.forename: Xian-Ping
authors.initials: XP
authors.lastname: Wu
authors.forename: Xiang-Hang
authors.initials: XH
authors.lastname: Luo
mesh_terms: D000818:Animals; D047369:Chromatin Immunoprecipitation; D019295:Computational Biology / Q000379:methods; D025461:Feedback, Physiological; D005786:Gene Expression Regulation; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010006:Osteoblasts / Q000166:cytology*; D012333:RNA, Messenger / Q000378:metabolism; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors / Q000378:metabolism*; D016335:Zinc Fingers
chemical_list: C543350:MIRN93 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger; D000076182:Sp7 Transcription Factor; C478163:SP7 protein, human; D014157:Transcription Factors