title: miR-181a promotes osteoblastic differentiation through repression of TGF-β signaling molecules.
abstract: Osteoblastic differentiation is controlled by complex interplay of several signaling pathways and associated key transcription factors, as well as by microRNAs (miRNAs). In our current study, we found miR-181a to be highly upregulated during BMP induced osteoblastic differentiation of C2C12 and MC3T3 cells. Overexpression of miR-181a led to upregulation of key markers of osteoblastic differentiation as well as enhanced ALP levels and Alizarin red staining, indicating the importance of this miRNA for osteoblastic differentiation. Further, we show that miR-181 isoforms (181a, 181b, 181c) are expressed during different stages of mouse calvarial and tibial development, implying their role in both endochondral and intramembranous ossification. We found several direct and indirect targets of miR-181a to be downregulated by global mRNA expression profiling. Our results demonstrate that miR-181a promotes osteoblastic differentiation via repression of TGF-β signaling molecules by targeting the negative regulator of osteoblastic differentiation Tgfbi (Tgf-beta induced) and TβR-I/Alk5 (TGF-β type I receptor). Furthermore, our findings suggest that Rgs4 and Gata6 are direct targets of miR-181a. Taken together, we provide evidence for a crucial functional link between a specific miRNA, miR-181a and osteoblastic differentiation.
authors.affiliation: Institute for Chemistry and Biochemistry, Freie Universitaet Berlin, Berlin, Germany.
authors.forename: Raghu
authors.initials: R
authors.lastname: Bhushan
authors.forename: Johannes
authors.initials: J
authors.lastname: Grünhagen
authors.forename: Jessica
authors.initials: J
authors.lastname: Becker
authors.forename: Peter N
authors.initials: PN
authors.lastname: Robinson
authors.forename: Claus-Eric
authors.initials: CE
authors.lastname: Ott
authors.forename: Petra
authors.initials: P
authors.lastname: Knaus
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002454:Cell Differentiation; D050993:GATA6 Transcription Factor / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D020710:RGS Proteins / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D019485:Bone Morphogenetic Proteins; D050993:GATA6 Transcription Factor; C494760:Gata6 protein, mouse; D035683:MicroRNAs; D020710:RGS Proteins; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; C529100:mirn181 microRNA, mouse; C098799:RGS4 protein; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625842:Tgfbr1 protein, mouse