Developmental characterization of the gene for laminin alpha-chain in sea urchin embryos.
We describe the isolation and characterization of a cDNA clone encoding a region of the carboxy terminal globular domain (G domain) of the alpha-1 chain of laminin from the sea urchin, Strongylocentrotus purpuratus. Sequence analysis indicates that the 1.3 kb cDNA (spLAM-alpha) encodes the complete G2 and G3 subdomains of sea urchin a-laminin. The 11 kb spLAM-alpha mRNA is present in the egg and declines slightly in abundance during development to the pluteus larva. The spLAM-alpha gene is also expressed in a variety of adult tissues. Whole mount in situ hybridization of gastrula stage embryos indicates that ectodermal and endodermal epithelia and mesenchyme cells contain the spLAM-alpha mRNA. Immunoprecipitation experiments using an antibody made to a recombinant fusion protein indicates spLAM-alpha protein is synthesized continuously from fertilization as a 420 kDa protein which accumulates from low levels in the egg to elevated levels in the pluteus larva. Light and electron microscopy identify spLAM-alpha as a component of the basal lamina. Blastocoelic microinjection of an antibody to recombinant spLAM-alpha perturbs gastrulation and skeleton formation by primary mesenchyme cells suggesting an important role for laminin in endodermal and mesodermal morphogenesis.
D000818:Animals; D001485:Basement Membrane / Q000648:ultrastructure; D015152:Blotting, Northern; D001842:Bone and Bones / Q000196:embryology; D018076:DNA, Complementary / Q000378:metabolism; D005775:Gastrula / Q000378:metabolism / Q000473:pathology; D015723:Gene Library; D015151:Immunoblotting; D017403:In Situ Hybridization; D007797:Laminin / Q000235:genetics* / Q000378:metabolism; D008845:Microinjections; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D011233:Precipitin Tests; D012617:Sea Urchins / Q000196:embryology*; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014018:Tissue Distribution