title: Mouse fibroblasts null for the long isoform of β1,4-galactosyltransferase-I show defective cell-matrix interactions.
abstract: β1,4 Galactosyltransferase-I (GalT-I) is expressed as two nearly identical polypeptides that differ only in the length of their cytoplasmic domains. The longer isoform has been implicated as a cell surface receptor for extracellular glycoside ligands, such as laminin. To more stringently test the function of the long GalT-I isoform during cell interactions with laminin, we created multiple independent fibroblastic cell lines that fail to express the long isoform, but which express the short GalT-I isoform normally and appear to have normal intracellular galactosylation. Cells devoid of the long GalT-I isoform are unable to adhere and spread on laminin substrates as well as control cells, but retain near normal interactions with fibronectin, which do not rely upon surface GalT-I function. The loss of the long GalT-I isoform also leads to a loss of actin stress fibers, focal adhesions and rac GTPase activation.
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Brooke H
authors.initials: BH
authors.lastname: Elder
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA. Electronic address: barryshur@gmail.com.
authors.forename: Barry D
authors.initials: BD
authors.lastname: Shur
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D002450:Cell Communication / Q000187:drug effects; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D021982:Cell-Matrix Junctions / Q000187:drug effects / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts / Q000378:metabolism*; D005353:Fibronectins / Q000494:pharmacology; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism; D007797:Laminin / Q000494:pharmacology; D051379:Mice; D009237:N-Acetyllactosamine Synthase / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D022502:Stress Fibers / Q000187:drug effects / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000378:metabolism
chemical_list: D005353:Fibronectins; D007797:Laminin; D020033:Protein Isoforms; D009237:N-Acetyllactosamine Synthase; D020744:rac GTP-Binding Proteins
keywords: Cell surface GalT-I; Cell-matrix interactions; Laminin receptors; β1,4-galactosyltransferase-I