title: Heparin-binding EGF-like growth factor and miR-1192 exert opposite effect on Runx2-induced osteogenic differentiation.
abstract: Osteoblast differentiation is a pivotal event in bone formation. Runt-related transcription factor-2 (Runx2) is an essential factor required for osteoblast differentiation and bone formation. However, the underlying mechanism of Runx2-regulated osteogenic differentiation is still unclear. Here, we explored the corresponding mechanism using the C2C12/Runx2(Dox) subline, which expresses Runx2 in response to doxycycline (Dox). We found that Runx2-induced osteogenic differentiation of C2C12 cells results in a sustained decrease in the expression of heparin-binding EGF-like growth factor (HB-EGF), a member of the epidermal growth factor (EGF) family. Forced expression of HB-EGF or treatment with HB-EGF is capable of reducing the expression of alkaline phosphatase (ALP), a defined marker of early osteoblast differentiation. HB-EGF-mediated inhibition of ALP depends upon activation of the EGFR and the downstream extracellular signal-regulated kinase, c-Jun N-terminal kinase mitogen-activated protein kinase pathways as well as phosphatidylinositol 3-kinase/Akt pathway. Runx2 specifically binds to the Hbegf promoter, suggesting that Hbegf transcription is directly inhibited by Runx2. Runx2 can upregulate miR-1192, which enhances Runx2-induced osteogenic differentiation. Moreover, miR-1192 directly targets Hbegf through translational inhibition, suggesting enhancement of Runx2-induced osteogenic differentiation by miR-1192 through the downregulation of HB-EGF. Taken together, our results suggest that Runx2 induces osteogenic differentiation of C2C12 cells by inactivating HB-EGF-EGFR signaling through the downregulation of HB-EGF via both transcriptional and post-transcriptional mechanisms.
authors.affiliation: Institute of Biomedicine, College of Life Science and Technology, Jinan University, Guangdong, Guangzhou, People's Republic of China.
authors.forename: S
authors.initials: S
authors.lastname: Yu
authors.forename: Q
authors.initials: Q
authors.lastname: Geng
authors.forename: J
authors.initials: J
authors.lastname: Ma
authors.forename: F
authors.initials: F
authors.lastname: Sun
authors.forename: Y
authors.initials: Y
authors.lastname: Yu
authors.forename: Q
authors.initials: Q
authors.lastname: Pan
authors.forename: A
authors.initials: A
authors.lastname: Hong
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation / Q000235:genetics*; D002460:Cell Line; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism*; D015536:Down-Regulation / Q000235:genetics; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D024510:Muscle Development / Q000235:genetics; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D010012:Osteogenesis / Q000235:genetics*; D014176:Protein Biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000235:genetics
chemical_list: D020413:3' Untranslated Regions; D050659:Core Binding Factor Alpha 1 Subunit; C587884:Hbegf protein, mouse; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; C586895:MIRN1192 microRNA, mouse; D035683:MicroRNAs; D012333:RNA, Messenger; D012097:Repressor Proteins