title: Mechanical strain induces collagenase-3 (MMP-13) expression in MC3T3-E1 osteoblastic cells.
abstract: Mechanical strain plays a crucial role in bone remodeling during growth and development and healing of bone besides systemic and local factors. One of the major factors involves in remodeling process is matrix metalloproteinases (MMPs) such as MMP-13 that has been shown to degrade the native interstitial collagens in several tissues. To study how mechanical strain affects extracellular matrix degradation by MMP-13, a biaxial strain was applied to MC3T3-E1 osteoblastic cells plated onto a collagen-coated flexible elastic membrane. The MMP-13 protein and mRNA expression were determined by Western blotting and reverse transcriptase-PCR, respectively. The zymographic activities of MMP-13 increased dramatically at 30 min, reached a peak by 2-fold at 1 h, and maintained up to 4 h. Moreover, the MMP-13 and c-fos mRNA expressed at 5 min, increased to 2.8- and 3-fold at 1 h, respectively, and gradually declined thereafter. Cycloheximide and actinomycin D did not inhibit the MMP-13 and c-fos mRNA expression, suggesting that such expression does not require de novo protein synthesis and not change their stabilities. To investigate which of the mitogen-activated protein kinase (MAPK) pathways involves in the expression of MMP-13, inhibitors such as PD98059, SB203580, and SP600125 were used. However, only PD98059 (an inhibitor of MEK1/2 activation) inhibited MMP-13 and c-fos gene expression; the result was further substantiated by transfecting with the dominant negative mutants of MEK1/2 (MEK K97R) and ERK2. Taken together, our results showed that mechanical strain induces the MMP-13 expression through MEK-ERK signaling pathway to regulate mechanical adaptation.
authors.affiliation: Department of Pharmacology, College of Medicine, Chang Gung University, Tao-Yuan 333, Taiwan.
authors.forename: Chuen-Mao
authors.initials: CM
authors.lastname: Yang
authors.forename: Chin-Sung
authors.initials: CS
authors.lastname: Chien
authors.forename: Chung-Chen
authors.initials: CC
authors.lastname: Yao
authors.forename: Li-Der
authors.initials: LD
authors.lastname: Hsiao
authors.forename: Yu-Chen
authors.initials: YC
authors.lastname: Huang
authors.forename: Chou Bing
authors.initials: CB
authors.lastname: Wu
mesh_terms: D016475:3T3 Cells; D000818:Animals; D015153:Blotting, Western; D003094:Collagen / Q000378:metabolism; D017364:Collagenases / Q000096:biosynthesis* / Q000378:metabolism; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D003720:Densitometry; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005799:Genes, Dominant; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020935:MAP Kinase Signaling System; D053509:Matrix Metalloproteinase 13; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009154:Mutation; D010006:Osteoblasts / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013314:Stress, Mechanical; D013997:Time Factors; D014162:Transfection
chemical_list: D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D003609:Dactinomycin; D003094:Collagen; D003513:Cycloheximide; D011505:Protein-Tyrosine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D017364:Collagenases; D053509:Matrix Metalloproteinase 13; C507081:Mmp13 protein, mouse