Matrix assembly, regulation, and survival functions of laminin and its receptors in embryonic stem cell differentiation.
Laminin-1 is essential for early embryonic basement membrane assembly and differentiation. Several steps can be distinguished, i.e., the expression of laminin and companion matrix components, their accumulation on the cell surface and assembly into basement membrane between endoderm and inner cell mass, and the ensuing differentiation of epiblast. In this study, we used differentiating embryoid bodies derived from mouse embryonic stem cells null for gamma1-laminin, beta1-integrin and alpha/beta-dystroglycan to dissect the contributions of laminin domains and interacting receptors to this process. We found that (a) laminin enables beta1-integrin-null embryoid bodies to assemble basement membrane and achieve epiblast with beta1-integrin enabling expression of the laminin alpha1 subunit; (b) basement membrane assembly and differentiation require laminin polymerization in conjunction with cell anchorage, the latter critically dependent upon a heparin-binding locus within LG module-4; (c) dystroglycan is not uniquely required for basement membrane assembly or initial differentiation; (d) dystroglycan and integrin cooperate to sustain survival of the epiblast and regulate laminin expression; and (e) laminin, acting via beta1-integrin through LG1-3 and requiring polymerization, can regulate dystroglycan expression.
Li
Shaohua
S
Department of Pathology and Laboratory Medicine, University of Medicine and Dentistry of New Jersey (UMDNJ), Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.
Harrison
David
D
Carbonetto
Salvatore
S
Fassler
Reinhard
R
Smyth
Neil
N
Edgar
David
D
Yurchenco
Peter D
PD
D000818:Animals; D017209:Apoptosis; D001485:Basement Membrane / Q000378:metabolism / Q000648:ultrastructure; D001665:Binding Sites; D002454:Cell Differentiation; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism; D049030:Dystroglycans; D006493:Heparin / Q000378:metabolism; D019012:Integrin beta1 / Q000378:metabolism; D007797:Laminin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D008958:Models, Molecular; D009154:Mutation; D020033:Protein Isoforms / Q000502:physiology; D017434:Protein Structure, Tertiary; D017474:Receptors, Laminin / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013234:Stem Cells / Q000502:physiology* / Q000648:ultrastructure
D003598:Cytoskeletal Proteins; D019012:Integrin beta1; D007797:Laminin; D008562:Membrane Glycoproteins; D020033:Protein Isoforms; D017474:Receptors, Laminin; D011994:Recombinant Proteins; D049030:Dystroglycans; D006493:Heparin