MT1-MMP shedding involves an ADAM and is independent of its localization in lipid rafts |
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Authors: | Toth Marta Sohail Anjum Mobashery Shahriar Fridman Rafael |
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Affiliation: | Department of Chemistry and Biochemistry and the Walther Cancer Research Center, University of Notre Dame, Notre Dame, IN 46556, USA. |
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Abstract: | The membrane type 1-matrix metalloproteinase (MT1-MMP) is a membrane-anchored protease that its entire ectodomain is shed from the cell surface. Here we show that in HT1080 cells MT1-MMP is shed as two soluble forms of approximately 52 and approximately 50kDa. Analyses in purified HT1080 plasma membranes show that release of these species is a two-step time-dependent process that is mediated by integral membrane metalloprotease(s). Differential sensitivity to TIMP-3 inhibition of the shedding process suggests that the second cleavage step leading to the formation of the 50-kDa soluble species is mediated by an ADAM. We also show that shedding of MT1-MMP is independent of its partition into lipid rafts because both wild type and glycosylphosphatidylinositol (GPI)-anchored MT1-MMP are shed. These studies provide new insights into the process of MT1-MMP ectodomain shedding, which may regulate pericellular proteolysis. |
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Keywords: | Matrix metalloproteinases Ectodomain shedding Plasma membrane Tissue inhibitors of metalloproteinases Protease inhibitors Lipid rafts |
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