Author
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Hausman, Gary |
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Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only Publication Acceptance Date: 4/21/2005 Publication Date: 7/20/2005 Citation: Hausman, G.J. 2005. Tissue proteolytic enzymes: modifiers of muscle and adipose tissue [abstract]. Journal of Animal Science Supplement. 83(1):208. Interpretive Summary: Technical Abstract: Degradation or proteolysis of ECM proteins is implicated in cell attachment, cell migration / ECM invasion, angiogenesis and release and processing of membrane bound cytokines and growth factors. Extracellular proteolysis involves several families of proteolytic enzymes, including the plasminogen activator (PA) - plasmin system, the adamalysins (ADAMs) family and the matrixin matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). The MMP family is the most prominent of these protease families and MMP-2, MMP-9, TIMP-1 and TIMP-2 are the most prominent and most studied components of the MMP regulatory system. Expression of MMPs is critical to development since deficiencies in both MMP-2 and MMP-14 is lethal and MMP-9 deficiency results in transient abnormal bone development. Many MMPs including MMP-2 and MMP-9 and TIMPs are expressed by both skeletal muscle and isolated myogenic cells and fibroblasts and by adipose tissue and isolated stromal-vascular cells in a depot dependent manner. The role of extracellular proteolysis in myogenesis is discussed including the evidence that MMPs and the PA- plasmin system components mediate myoblast migration and fusion. The ramifications of the influence of PA inhibitor-1 (PAI-1) on migration of preadipocytes and associated endothelial cells will be discussed. Finally, evidence that MMPs and, in particular, MMP-9 mediate adipocyte differentiation in vitro will be reviewed. |
