title: Activation of matrix metalloproteinase-2 from hepatic stellate cells requires interactions with hepatocytes.
abstract: Activation of matrix metalloproteinase (MMP)-2, the 72-kd collagenase IV/gelatinase A, is involved in extracellular matrix remodeling. It has been suggested that a membrane-type MMP (MT-MMP-1) and the tissue inhibitor of metalloproteinase (TIMP)-2 are involved in MMP-2 processing, but the exact mechanism(s) of its activation remains unclear. We have investigated the role of cell-cell cooperation in the activation of pro-MMP-2 in the liver, using pure cultures and co-cultures of hepatocytes and hepatic stellate cells (HSCs). Northern blot analysis and in situ hybridization showed that, in both pure and co-cultures, HSCs, but not hepatocytes, expressed MMP-2, TIMP-2, and MT-MMP-1 mRNA. Zymography analyses revealed the latent form of MMP-2 in medium from 2-day-old pure HSC cultures with higher amounts in medium from hepatocyte/HSC co-cultures. When hepatocytes were added to 10-day-old HSC cultures, the activated form of MMP-2 was detected, concomitantly with the deposition of an abundant extracellular matrix. Incubation of plasma membrane-enriched fractions from hepatocytes with conditioned medium from pure HSC cultures generated the activated species of MMP-2 (62 and 59 kd). Activation of pro-MMP-2 by hepatocyte membranes was inhibited by EDTA, heat, and trypsin but not by serine proteinase inhibitors. These data show that the co-expression of TIMP-2, MMP-2, and MT-MMP-1 by HSCs does not lead to secretion of the activated form of MMP-2. Hepatocytes, which do not express MMP-2, TIMP-2, or MT-MMP-1, induce MMP-2 activation through a plasma membrane-dependent mechanism(s), thus suggesting that cell-cell interactions are involved in this process in vivo.
authors.affiliation: Detoxication and Tissue Repair Unit INSERM, U-456, Rennes I University School of Medicine, France.
authors.forename: N
authors.initials: N
authors.lastname: Théret
authors.forename: O
authors.initials: O
authors.lastname: Musso
authors.forename: A
authors.initials: A
authors.lastname: L'Helgoualc'h
authors.forename: B
authors.initials: B
authors.lastname: Clément
mesh_terms: D000818:Animals; D002450:Cell Communication; D018920:Coculture Techniques; D017364:Collagenases / Q000235:genetics; D004789:Enzyme Activation; D005109:Extracellular Matrix / Q000378:metabolism; D018093:Gelatinases / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000166:cytology* / Q000201:enzymology*; D008297:Male; D020781:Matrix Metalloproteinase 1; D020778:Matrix Metalloproteinase 2; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D019716:Tissue Inhibitor of Metalloproteinase-2
chemical_list: D011506:Proteins; D012333:RNA, Messenger; D019716:Tissue Inhibitor of Metalloproteinase-2; D017364:Collagenases; D018093:Gelatinases; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2; D020781:Matrix Metalloproteinase 1