title: Cbfa-1 mediates nitric oxide regulation of MMP-13 in osteoblasts.
abstract: During bone development, osteoblast differentiation requires remodeling of the extracellular matrix. Although underlying mechanisms have not been elucidated, evidence points to the participation of the nitric oxide (NO) and cyclic guanosine 3',5'-monophosphate (cGMP) system. Here, we detected increased matrix metalloproteinase (MMP)-13 mRNA, protein and activity, as well as increased inducible NO synthase (iNOS) and NO production during the differentiation of MC3T3-E1 osteoblasts. Transcriptional activity of the MMP-13 promoter was augmented by NO, 8-bromo-cGMP (8-Br-cGMP), and by a dominant-positive form of protein kinase G (PKG1-alpha). The stimulatory effect on the MMP-13 promoter was partially inhibited by mutation of the osteoblast-specific element 2 (OSE-2) binding site. Core binding factor-1 (Cbfa-1) expression peaked at 7 days of differentiation, and was phosphorylated by PKG in vitro. Cbfa-1 was localized to cell nuclei, and its translocation was inhibited by the iNOS inhibitor 1400W. Immunohistological examination revealed that MMP-13 and Cbfa-1 expression levels are both reduced in 17-day-old embryos of iNOS-deficient mice. Silencing of Cbfa-1 mRNA blocked MMP-13 expression without interfering with endogenous NO production, confirming its role in NO-induced MMP-13 expression by MC3T3-E1 cells. The results described here suggest a mechanism by which NO regulates osteogenesis.
authors.affiliation: Fundación Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain. czaragoza@cnic.es
authors.forename: Carlos
authors.initials: C
authors.lastname: Zaragoza
authors.forename: Esther
authors.initials: E
authors.lastname: López-Rivera
authors.forename: Concepción
authors.initials: C
authors.lastname: García-Rama
authors.forename: Marta
authors.initials: M
authors.lastname: Saura
authors.forename: Antonio
authors.initials: A
authors.lastname: Martínez-Ruíz
authors.forename: Tania R
authors.initials: TR
authors.lastname: Lizarbe
authors.forename: Fernando
authors.initials: F
authors.lastname: Martín-de-Lara
authors.forename: Santiago
authors.initials: S
authors.lastname: Lamas
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D020868:Gene Silencing; D006801:Humans; D053509:Matrix Metalloproteinase 13 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D015290:Second Messenger Systems / Q000502:physiology; D014158:Transcription, Genetic
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; D012333:RNA, Messenger; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D017869:Cyclic GMP-Dependent Protein Kinases; D053509:Matrix Metalloproteinase 13; D006152:Cyclic GMP