title: Regulation of collagenase-3 and osteocalcin gene expression by collagen and osteopontin in differentiating MC3T3-E1 cells.
abstract: Both collagenase-3 and osteocalcin mRNAs are expressed maximally during the later stages of osteoblast differentiation. Here, we demonstrate that collagenase-3 mRNA expression in differentiating MC3T3-E1 cells is dependent upon the presence of ascorbic acid, is inhibited in the presence of the collagen synthesis inhibitor, 3,4-dehydroproline, and is stimulated by growth on collagen in the absence of ascorbic acid. Transient transfection studies show that collagenase-3 promoter activity increases during cell differentiation and requires the presence of ascorbic acid. Additionally, we show that, in differentiating MC3T3-E1 cells, collagenase-3 gene expression increases in the presence of an anti-osteopontin monoclonal antibody that binds near the RGD motif of this protein, whereas osteocalcin expression is inhibited. Furthermore, an RGD peptidomimetic compound, designed to block interaction of ligands to the alpha(v) integrin subunit, increases osteocalcin expression and inhibits collagenase-3 expression, suggesting that the RGD peptidomimetic initiates certain alpha(v) integrin signaling in osteoblastic cells. Overall, these studies demonstrate that stimulation of collagenase-3 expression during osteoblast differentiation requires synthesis of a collagenous matrix and that osteopontin and alpha(v) integrins exert divergent regulation of collagenase-3 and osteocalcin expression during osteoblast differentiation.
authors.affiliation: Department of Physiology and Biophysics, Robert Wood Johnson Medical School and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: Richard C
authors.initials: RC
authors.lastname: D'Alonzo
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Kowalski
authors.forename: David T
authors.initials: DT
authors.lastname: Denhardt
authors.forename: G Allen
authors.initials: GA
authors.lastname: Nickols
authors.forename: Nicola C
authors.initials: NC
authors.lastname: Partridge
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D002454:Cell Differentiation; D003094:Collagen / Q000502:physiology*; D017364:Collagenases / Q000235:genetics*; D005786:Gene Expression Regulation; D015971:Gene Expression Regulation, Enzymologic; D007700:Kinetics; D053509:Matrix Metalloproteinase 13; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology; D015675:Osteocalcin / Q000235:genetics*; D053495:Osteopontin; D011392:Proline / Q000031:analogs & derivatives* / Q000494:pharmacology; D011994:Recombinant Proteins / Q000096:biosynthesis; D012795:Sialoglycoproteins / Q000276:immunology / Q000502:physiology*; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D009842:Oligopeptides; D011994:Recombinant Proteins; D012795:Sialoglycoproteins; C506896:Spp1 protein, mouse; D015675:Osteocalcin; D053495:Osteopontin; C002195:3,4-dehydroproline; C047981:arginyl-glycyl-aspartic acid; D003094:Collagen; D011392:Proline; D017364:Collagenases; D053509:Matrix Metalloproteinase 13; C507081:Mmp13 protein, mouse; D001205:Ascorbic Acid