title: Transmembrane-deletion mutants of the membrane-type matrix metalloproteinase-1 process progelatinase A and express intrinsic matrix-degrading activity.
abstract: Membrane-type matrix metalloproteinase-1 (MT-MMP-1) has been proposed to play a critical role in regulating the expression of tissue-invasive phenotypes in normal and neoplastic cells by directly or indirectly mediating the activation of progelatinase A. To begin characterizing MT-MMP-1 structure-function relationships, transmembrane-deletion mutants were constructed, and the processing of the zymogens as well as the enzymic activity of the mature proteinases was analyzed. We now demonstrate that pro-MT-MMP-1 mutants are efficiently processed to active proteinases following post-translational endoproteolysis immediately downstream of an Arg108-Arg-Lys-Arg basic motif by a proprotein convertase-dependent pathway. The secreted form of active MT-MMP-1 not only displays an N terminus identical with that described for the processed wild-type enzyme at Tyr112 (Strongin, A. Y., Collier, I., Bannikov, G., Marmer, B. L., Grants, G. A., and Goldberg, G. I. (1995) J. Biol. Chem. 270, 5331-5338), but also directly mediated progelatinase A activation via a two-step proteolytic cascade indistinguishable from that observed with intact cells. Furthermore, although the only function previously ascribed to MT-MMP-1 is its ability to act as a progelatinase A activator, purified transmembrane deletion mutants also expressed proteolytic activities against a wide range of extracellular matrix molecules. Given recent reports that MT-MMP-1 ectodomains may undergo intercellular transfer in vivo (Okada, A., Bellocq, J.-P., Rouyer, N., Chenard, M.-P., Rio, M.-C., Chambon, P., and Basset, P. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 2730-2734), our data suggest that soluble forms of the proteinase confer recipient cells with the ability to not only process progelatinase A, but also directly degrade extracellular matrix components.
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Comprehensive Cancer Center, Ann Arbor, 48109, USA.
authors.forename: D
authors.initials: D
authors.lastname: Pei
authors.forename: S J
authors.initials: SJ
authors.lastname: Weiss
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002522:Chlorocebus aethiops; D017364:Collagenases / Q000737:chemistry / Q000378:metabolism*; D017931:DNA Primers / Q000737:chemistry; D004285:Dogs; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism*; D018093:Gelatinases / Q000378:metabolism*; D006801:Humans; D020781:Matrix Metalloproteinase 1; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008666:Metalloendopeptidases / Q000378:metabolism*; D008969:Molecular Sequence Data; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014162:Transfection
chemical_list: D017931:DNA Primers; D004792:Enzyme Precursors; D008565:Membrane Proteins; D017364:Collagenases; D018093:Gelatinases; D008666:Metalloendopeptidases; C069860:progelatinase; D020781:Matrix Metalloproteinase 1