Cleavage at the stem region releases an active ectodomain of the membrane type 1 matrix metalloproteinase.
MT1-MMP (membrane type 1 matrix metalloproteinase) is a membrane-anchored MMP that can be shed to the extracellular milieu. In the present study we report the primary structure and activity of the major soluble form of MT1-MMP. MS analysis of the purified 50-kDa soluble MT1-MMP form shows that the enzyme extends from Tyr112 to Val524, indicating that formation of this species requires a proteolytic cleavage within the stem region. In agreement, deletion of the entire stem region of MT1-MMP inhibited shedding of the 50-kDa species. A recombinant 50-kDa species (Tyr112-Val524) expressed in cells exhibited enzymatic activity against pro-MMP-2 and galectin-3, and thus this species is a competent protease. The recombinant 50-kDa soluble form also decreased the level of surface-associated TIMP-2 (tissue inhibitor of metalloproteinase 2) when administered to cells expressing wild-type membrane-anchored MT1-MMP, suggesting that ectodomain shedding of MT1-MMP can alter the MMP/TIMP balance on the cell surface. A approximately 53-kDa species of MT1-MMP was also isolated from a non-detergent extract of human breast carcinoma tissue and was found to lack the cytosolic tail, as determined with specific MT1-MMP domain antibodies. Together, these data show that MT1-MMP ectodomain shedding is a physiological process that may broaden MT1-MMP activity to the pericellular space.
Toth
Marta
M
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
Osenkowski
Pamela
P
Hesek
Dusan
D
Brown
Stephen
S
Meroueh
Samy
S
Sakr
Wael
W
Mobashery
Shahriar
S
Fridman
Rafael
R
D020816:Amino Acid Motifs; D000818:Animals; D001940:Breast / Q000201:enzymology; D001943:Breast Neoplasms / Q000201:enzymology; D002384:Catalysis; D002460:Cell Line; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053504:Matrix Metalloproteinases, Membrane-Associated; D008565:Membrane Proteins; D008666:Metalloendopeptidases / Q000737:chemistry* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012995:Solubility; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism
D008565:Membrane Proteins; D019716:Tissue Inhibitor of Metalloproteinase-2; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases