Role of laminin terminal globular domains in basement membrane assembly.
Laminins contribute to basement membrane assembly through interactions of their N- and C-terminal globular domains. To further analyze this process, recombinant laminin-111 heterotrimers with deletions and point mutations were generated by recombinant expression and evaluated for their ability to self-assemble, interact with nidogen-1 and type IV collagen, and form extracellular matrices on cultured Schwann cells by immunofluorescence and electron microscopy. Wild-type laminin and laminin without LG domains polymerized in contrast to laminins with deleted alpha1-, beta1-, or gamma1-LN domains or with duplicated beta1- or alpha1-LN domains. Laminins with a full complement of LN and LG domains accumulated on cell surfaces substantially above those lacking either LN or LG domains and formed a lamina densa. Accumulation of type IV collagen onto the cell surface was found to require laminin with separate contributions arising from the presence of laminin LN domains, nidogen-1, and the nidogen-binding site in laminin. Collectively, the data support the hypothesis that basement membrane assembly depends on laminin self-assembly through formation of alpha-, beta-, and gamma-LN domain complexes and LG-mediated cell surface anchorage. Furthermore, type IV collagen recruitment into the laminin extracellular matrices appears to be mediated through a nidogen bridge with a lesser contribution arising from a direct interaction with laminin.
McKee
Karen K
KK
Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
Harrison
David
D
Capizzi
Stephanie
S
Yurchenco
Peter D
PD
D000818:Animals; D001485:Basement Membrane / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D003094:Collagen / Q000737:chemistry; D024141:Collagen Type IV / Q000737:chemistry; D017353:Gene Deletion; D006801:Humans; D007797:Laminin / Q000737:chemistry*; D008562:Membrane Glycoproteins / Q000737:chemistry; D051379:Mice; D017354:Point Mutation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley
D024141:Collagen Type IV; D007797:Laminin; D008562:Membrane Glycoproteins; C029967:nidogen; D003094:Collagen