Proteolytic processing of laminin-5 by MT1-MMP in tissues and its effects on epithelial cell morphology.
The extracellular matrix macromolecule laminin-5 (Ln-5) is converted by matrix metalloproteinases (MMP) MT1-MMP and MMP-2 into a migration-promoting substrate in vitro. We now report that cleavage of Ln-5 by MT1-MMP occurs in vivo and affects epithelial tissue organization and probably Ln-5 turnover. In MT1-MMP knockout (KO) mice, the kidneys showed increased levels of total Ln-5 gamma2 subunit, but significantly reduced amounts of gamma2', an amino-terminal truncated proteolytic form of gamma2. The kidney tubular epithelia of KO animals were poorly differentiated, a phenotype reminiscent of human congenital mixed hypoplastic/dysplastic disorders. To establish a better link between Ln-5 proteolytic cleavage and epithelial morphology, MT1-MMP expression was reconstituted by transfection of MT1-MMP into a Ln-5 positive, MT1-MMP deficient epithelial cell line. MT1-MMP transfectants demonstrated increased levels of processed Ln-5 gamma2 chain and enhanced spreading on Ln-5, but not fibronectin. Recombinant MT1-MMP cleaved gamma2 constructs in vitro at a known in vivo gamma2 gamma2' processing site. These results strongly indicate that Ln-5 is a physiological substrate of MT1-MMP in vivo. Proteolytic processing of gamma2 subunit by MT1-MMP may influence Ln-5 turnover in epithelial basement membranes and affect epithelial morphogenesis.
Koshikawa
Naohiko
N
The Scripps Research Institute, Department of Cell Biology, La Jolla California, USA.
Schenk
Susann
S
Moeckel
Gilbert
G
Sharabi
Andrew
A
Miyazaki
Kaoru
K
Gardner
Humphrey
H
Zent
Roy
R
Quaranta
Vito
V
D000818:Animals; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D002465:Cell Movement; D048429:Cell Size; D004847:Epithelial Cells / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology*; D007668:Kidney / Q000002:abnormalities / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D053511:Matrix Metalloproteinase 14; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D011499:Protein Processing, Post-Translational; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D000097794:Kalinin
D015815:Cell Adhesion Molecules; D053511:Matrix Metalloproteinase 14; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D021122:Protein Subunits; D000097794:Kalinin; C507096:Mmp14 protein, mouse