Involvement of matrix metalloproteinases in the adipose conversion of 3T3-L1 preadipocytes.
When mouse 3T3-L1 preadipocytes are induced to differentiate into adipocytes, they change from an extended fibroblast-like morphology to a rounded one. This change most likely occurs through extracellular matrix remodelling, a process known to be mediated in part by matrix metalloproteinases (MMPs). In this study, we have shown by semi-quantitative reverse transcriptase-PCR, zymographic and immunoblot analysis that MMP-2, MMP-9 and membrane type 1 (MT1)-MMP are regulated during adipose conversion. To assess the importance of MMPs for adipocytic differentiation we have used MMP-specific inhibitors as well as neutralizing antibodies. Treatment of 3T3-L1 preadipocytes with the broad MMP inhibitor Ilomastat or the more restricted MMP-2 Inhibitor I prevented their differentiation into adipocytes in a dose-dependent manner, as evidenced by absence of triglyceride accumulation. Inhibitor treatment prevented the fibronectin-network degradation, as well as the induction of the genes for peroxisome-proliferator-activated receptor gamma and adipsin, two adipocyte phenotype markers. Inhibitor treatment was effective when applied during the early stages of adipocytic conversion, whereas inhibitor treatment during later stages had little effect. Inhibitor treatment did not inhibit clonal mitotic expansion; nor did it affect the expression pattern of the adipogenic transcription factor CCAAT/enhancer-binding protein beta (C/EBPbeta) or its nuclear translocation. It did, however, markedly reduce C/EBPbeta DNA-binding capacity. Taken together, these results suggest that MMPs, and notably MMP-2 and MMP-9, may be necessary mediators of adipocytic differentiation of 3T3-L1 cells.
Croissandeau
Gilles
G
Diseases of Aging Program, Ottawa Health Research Institute, University of Ottawa, Ottawa, Ontario K1Y 4K9, Canada.
Chrétien
Michel
M
Mbikay
Majambu
M
D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology* / Q000201:enzymology; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D006877:Hydroxamic Acids; D007211:Indoles / Q000494:pharmacology; D007700:Kinetics; D053511:Matrix Metalloproteinase 14; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000378:metabolism; D051379:Mice; D011480:Protease Inhibitors / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000906:Antibodies; D022782:CCAAT-Enhancer-Binding Protein-beta; D006877:Hydroxamic Acids; D007211:Indoles; C507096:Mmp14 protein, mouse; D011480:Protease Inhibitors; D020782:Matrix Metalloproteinases; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D053511:Matrix Metalloproteinase 14; C119203:ilomastat