Selective modulation of the interaction of alpha 7 beta 1 integrin with fibronectin and laminin by L-14 lectin during skeletal muscle differentiation.
The alpha 7 beta 1 integrin was originally identified and isolated from differentiating skeletal muscle and shown to be a laminin-binding protein (Song et al. (1992) J. Cell Biol. 117, 643-657). Expression of the alpha 7 gene and protein are developmentally regulated during skeletal muscle differentiation and have been used to identify cells at distinct stages of the myogenic lineage (George-Weinstein et al. (1993) Dev. Biol. 156, 209-229). The lactoside-binding protein L-14 exists as a dimer and has been localized on a variety of cells, in association with extracellular matrix. During myogenesis in vitro, L-14 is synthesized within replicating myoblasts but it is not secreted until these cells commence terminal differentiation and fusion into multinucleate fibers (Cooper and Barondes, J. Cell Biol. (1990) 110, 1681-1691). Addition of purified L-14 to myogenic cells plated on laminin inhibits myoblast spreading and fusion, suggesting that the L-14 lectin regulates muscle cell interactions with the extracellular matrix that are germane to myogenic development (Cooper et al. (1991) J. Cell Biol. 115, 1437-1448). We demonstrate here, using affinity chromatography and immunoblots, that alpha 7 beta 1 also binds to fibronectin and to the L-14 lectin. L-14 binds to both laminin and to the alpha 7 beta 1 integrin, and it can effectively inhibit the association of laminin and this integrin. Modulation of alpha 7 beta 1 interaction with its ligands by L-14 is selective: L-14 does not bind to fibronectin, nor does it interfere with the binding of fibronectin to alpha 7 beta 1.(ABSTRACT TRUNCATED AT 250 WORDS)
Gu
M
M
Department of Cell and Structural Biology, University of Illinois, Urbana 61801.
Wang
W
W
Song
W K
WK
Cooper
D N
DN
Kaufman
S J
SJ
D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D005353:Fibronectins / Q000378:metabolism*; D037483:Galectin 1; D006388:Hemagglutinins / Q000096:biosynthesis / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D016023:Integrins / Q000302:isolation & purification / Q000378:metabolism*; D007797:Laminin / Q000378:metabolism*; D008970:Molecular Weight; D009132:Muscles / Q000166:cytology* / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D017474:Receptors, Laminin / Q000378:metabolism; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D014407:Tumor Cells, Cultured
D005353:Fibronectins; D037483:Galectin 1; D006388:Hemagglutinins; D016023:Integrins; D007797:Laminin; D017474:Receptors, Laminin; D011994:Recombinant Proteins; C082908:integrin alpha7beta1