title: O-glycosylation regulates autolysis of cellular membrane type-1 matrix metalloproteinase (MT1-MMP).
abstract: MT1-MMP is a key enzyme in cancer cell invasion and metastasis. The activity of cellular MT1-MMP is regulated by furin-like proprotein convertases, TIMPs, shedding, autoproteolysis, dimerization, exocytosis, endocytosis, and recycling. Our data demonstrate that, in addition to these already known mechanisms, MT1-MMP is regulated by O-glycosylation of its hinge region. Insignificant autolytic degradation is characteristic for naturally expressed, glycosylated, MT1-MMP. In turn, extensive autolytic degradation, which leads to the inactivation of the protease and the generation of its C-terminal membrane-tethered degraded species, is a feature of overexpressed MT1-MMP. We have determined that incomplete glycosylation stimulates extensive autocatalytic degradation and self-inactivation of MT1-MMP. Self-proteolysis commences during the secretory process of MT1-MMP through the cell compartment to the plasma membrane. The strongly negatively charged sialic acid is the most important functional moiety of the glycopart of MT1-MMP. We hypothesize that sialic acid of the O-glycosylation cassette restricts the access of the catalytic domain to the hinge region and to the autolytic cleavage site and protects MT1-MMP from autolysis. Overall, our results point out that there is a delicate balance between glycosylation and self-proteolysis of MT1-MMP in cancer cells and that when this balance is upset the catalytically potent MT1-MMP pool is self-proteolyzed.
authors.affiliation: Burnham Institute for Medical Research, La Jolla, California 92037.
authors.forename: Albert G
authors.initials: AG
authors.lastname: Remacle
authors.affiliation: Burnham Institute for Medical Research, La Jolla, California 92037.
authors.forename: Alexei V
authors.initials: AV
authors.lastname: Chekanov
authors.affiliation: Burnham Institute for Medical Research, La Jolla, California 92037.
authors.forename: Vladislav S
authors.initials: VS
authors.lastname: Golubkov
authors.affiliation: Burnham Institute for Medical Research, La Jolla, California 92037.
authors.forename: Alexei Y
authors.initials: AY
authors.lastname: Savinov
authors.affiliation: Burnham Institute for Medical Research, La Jolla, California 92037.
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Rozanov
authors.affiliation: Burnham Institute for Medical Research, La Jolla, California 92037. Electronic address: strongin@burnham.org.
authors.forename: Alex Y
authors.initials: AY
authors.lastname: Strongin
mesh_terms: D000818:Animals; D016466:CHO Cells; D020134:Catalytic Domain; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006031:Glycosylation; D006801:Humans; D053511:Matrix Metalloproteinase 14; D020782:Matrix Metalloproteinases / Q000737:chemistry* / Q000378:metabolism; D053504:Matrix Metalloproteinases, Membrane-Associated; D051379:Mice; D008807:Mice, Inbred BALB C; D008957:Models, Genetic; D009368:Neoplasm Transplantation
chemical_list: C507096:Mmp14 protein, mouse; D020782:Matrix Metalloproteinases; D053504:Matrix Metalloproteinases, Membrane-Associated; D053511:Matrix Metalloproteinase 14