title: Smooth muscle cell phenotypic transition associated with calcification: upregulation of Cbfa1 and downregulation of smooth muscle lineage markers.
abstract: Bovine aortic smooth muscle cell (BASMC) cultures undergo mineralization on addition of the organic phosphate donor, beta-glycerophosphate (betaGP). Mineralization is characterized by apatite deposition on collagen fibrils and the presence of matrix vesicles, as has been described in calcified vascular lesions in vivo as well as in bone and teeth. In the present study, we used this model to investigate the molecular mechanisms driving vascular calcification. We found that BASMCs lost their lineage markers, SM22alpha and smooth muscle alpha-actin, within 10 days of being placed under calcifying conditions. Conversely, the cells gained an osteogenic phenotype as indicated by an increase in expression and DNA-binding activity of the transcription factor, core binding factor alpha1 (Cbfa1). Moreover, genes containing the Cbfa1 binding site, OSE2, including osteopontin, osteocalcin, and alkaline phosphatase were elevated. The relevance of these in vitro findings to vascular calcification in vivo was further studied in matrix GLA protein null (MGP(-/-)) mice whose arteries spontaneously calcify. We found that arterial calcification was associated with a similar loss in smooth muscle markers and a gain of osteopontin and Cbfa1 expression. These data demonstrate a novel association of vascular calcification with smooth muscle cell phenotypic transition, in which several osteogenic proteins including osteopontin, osteocalcin, and the bone determining factor Cbfa1 are gained. The findings suggest a positive role for SMCs in promoting vascular calcification.
authors.affiliation: Department of Bioengineering, University of Washington, Seattle, Washington, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Steitz
authors.forename: M Y
authors.initials: MY
authors.lastname: Speer
authors.forename: G
authors.initials: G
authors.lastname: Curinga
authors.forename: H Y
authors.initials: HY
authors.lastname: Yang
authors.forename: P
authors.initials: P
authors.lastname: Haynes
authors.forename: R
authors.initials: R
authors.lastname: Aebersold
authors.forename: T
authors.initials: T
authors.lastname: Schinke
authors.forename: G
authors.initials: G
authors.lastname: Karsenty
authors.forename: C M
authors.initials: CM
authors.lastname: Giachelli
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D001011:Aorta / Q000378:metabolism / Q000473:pathology; D002114:Calcinosis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D002130:Calcium Phosphates / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D002339:Carotid Arteries / Q000378:metabolism / Q000473:pathology; D002417:Cattle; D002478:Cells, Cultured; D050659:Core Binding Factor Alpha 1 Subunit; D050660:Core Binding Factors; D016326:Extracellular Matrix Proteins; D005994:Glycerophosphates; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009363:Neoplasm Proteins; D015675:Osteocalcin / Q000378:metabolism; D053495:Osteopontin; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D012795:Sialoglycoproteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000097568:Matrix Gla Protein
chemical_list: D000943:Antigens, Differentiation; D002130:Calcium Phosphates; D002135:Calcium-Binding Proteins; D050659:Core Binding Factor Alpha 1 Subunit; D050660:Core Binding Factors; D016326:Extracellular Matrix Proteins; D005994:Glycerophosphates; D009363:Neoplasm Proteins; D015675:Osteocalcin; D053495:Osteopontin; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D014157:Transcription Factors; D000097568:Matrix Gla Protein; C506895:SPP1 protein, human; C506896:Spp1 protein, mouse; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous; C031463:beta-glycerophosphoric acid