title: Plasma membrane-dependent activation of gelatinase A in human vascular endothelial cells.
abstract: The initiation of the angiogenic process requires a locally confined and time-limited proteolysis of the basement membrane (BM) components at the site of new vessel sprout. Gelatinase A, a member of the matrix metalloproteinase family, degrades BM type IV collagen and is involved in the BM breakdown by migrating tumor cells and endothelial cells (EC). Gelatinase A is synthesized as latent proenzyme and must be activated in order to express its proteolytic activity. A plasma membrane-dependent mechanism of activation has been described for several tumor and transformed cells lines. In the present study, we show that latent (72 kD) and mature (62-59 kD) forms of gelatinase A are present in EC membrane fraction from Triton X-114 extract while only latent form is found in the cytosolic fraction. The incubation of EC membrane fraction with exogenous latent gelatinase A resulted in a significant activation giving rise to 62-59 kD mature forms. 12-O-tetradecanoylphorbol-13-acetate (TPA), a strong potentiator of angiogenesis in vitro and in vivo, increases the amount of both latent and activated forms of gelatinase A in EC membrane fraction as well as the ability of this latter fraction to activate exogenous latent gelatinase A. We show that the mRNA transcript coding for the membrane-integrated MMP, the MT-MMP, previously described as a potential gelatinase A activator in invasive tumor cells is also expressed in vascular EC and is regulated through a TPA sensitive process. This enzyme may be responsible for membrane-dependent gelatinase A activation in normal vascular EC and may therefore be a determinant in the control of BM proteolysis during angiogenesis.
authors.affiliation: Laboratory of Cellular Biology, University of Liège, Belgium.
authors.forename: J M
authors.initials: JM
authors.lastname: Lewalle
authors.forename: C
authors.initials: C
authors.lastname: Munaut
authors.forename: B
authors.initials: B
authors.lastname: Pichot
authors.forename: D
authors.initials: D
authors.lastname: Cataldo
authors.forename: E
authors.initials: E
authors.lastname: Baramova
authors.forename: J M
authors.initials: JM
authors.lastname: Foidart
mesh_terms: D001483:Base Sequence; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology; D017077:Culture Media, Conditioned; D004730:Endothelium, Vascular / Q000201:enzymology* / Q000648:ultrastructure; D018093:Gelatinases / Q000378:metabolism*; D006801:Humans; D020778:Matrix Metalloproteinase 2; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D019716:Tissue Inhibitor of Metalloproteinase-2; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D017077:Culture Media, Conditioned; D011480:Protease Inhibitors; D011506:Proteins; D012333:RNA, Messenger; D019716:Tissue Inhibitor of Metalloproteinase-2; D018093:Gelatinases; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2