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B L Hogan

Publications and source records attributed to B L Hogan.

180 records · Page 10Linked to original sources
PubMed1981

Studies on the biosynthesis of laminin by murine parietal endoderm cells.

The biosynthesis and processing of the polypeptides A (Mr = 450 x 10(3)), B1 (Mr = 240 x 10(3)), B2 (Mr = 230 x 10(3)) and C (Mr = 150 x 10(3)) of the extracellular matrix protein, laminin, were studied in murine parietal endoderm cells labelled with [35S]methionine. Various lines of evidence suggest that the A chains are not precursors to the smaller B chains. Firstly, the pulse-chase experiments, radioactivity in cytoplasmic A and (B1 + B2) chains declines with the same half-life of about 70 min. Secondly, peptide maps generated by digestion of A and B (B1 + B2) chains with Staphylococcus aureus V8 protease are different. Finally, rabbit antibodies to isolated, denatured (B1 + B2) chains do not cross-react with reduced and alkylated A chains. A, B1, B2 and C polypeptides are all glycosylated by an intracellular process involving the addition of tunicamycin and endo-beta-N-acetylglucosaminidase-H-sensitive N-linked oligosaccharide side chains. Further glycosylation probably occurs around the time of secretion. Disulphide bonding of some A and B chains can be observed in the cytoplasm within 10 min of adding [35S]methionine. However, it appears that some free A and B2 chains are present in the cytoplasm and that free A chains exist in the medium. The relationship between the 150 x 10(3)-Mr C glycoprotein and the A and B components is discussed. Although B and C chains generate different peptide maps after digestion with S. aureus V8 protease, antibodies raised against isolated, denatured C chains cross-react with reduced and alkylated B (but not A) chains. This suggests that B and C chains may share some antigenic determinant(s).

Animals↗
PubMed1981

Cell interactions and endoderm differentiation in cultured mouse embryos.

Morphological and biochemical evidence is presented that the visceral extraembryonic endoderm of the 6.5-day mouse embryo will differentiate into parietal endoderm when cultured in contact with extraembryonic ectoderm undergoing transition into trophoblast giant cells. Egg cylinders from 6.5-day embryos were dissected into embryonic and extraembryonic halves and cultured in suspension in vitro for up to 7 days. After 4 days, the endoderm cells of the extraembryonic fragments morphologically resemble parietal endoderm, are associated with a thick basement membrane and synthesize large amounts of the matrix proteins laminin and Type IV procollagen. A similar transition in phenotype is not seen in the endoderm of embryonic fragments, nor in visceral extraembryonic endoderm cells cultured in isolation. In another series of experiments, complete egg cylinders were dissected free of visceral endoderm overlying the extraembryonic ectoderm and then cultured in vitro. The visceral endoderm cells which recolonize the surface of the extraembryonic ectoderm develop a parietal endoderm phenotype and lay down a thick basement membrane. These results suggest that the differentiation of the extraembryonic endoderm of the early mouse embryo into visceral and parietal phenotypes can be influenced by local cell-cell or cell-substrate interactions, and is not determined solely by cell lineage.

Animals↗
PubMedDate not supplied

The DVR gene family in embryonic development.

The DVR gene family consists of at least 15 members, including decapentaplegic from Drosophila, Xenopus Vg1 and the mammalian bone morphogenetic protein genes, encoding secreted proteins closely related to transforming growth factor beta Genetic and biochemical evidence supports the idea that DVR proteins form part of a cascade of extracellular signalling molecules mediating inductive tissue interactions during development.

Animals↗
PubMedDate not supplied

Co-expression of vimentin and cytokeratins in parietal endoderm cells of early mouse embryo.

Of the five classes of intermediate filaments found in vertebrate tissues, the cytokeratins are considered unique to epithelial tissues, while vimentin is expressed by endothelial and mesenchymal cells. In neither case is the precise function of the filament system known. Epithelial cells in culture often express vimentin as well as cytokeratins, but co-expression in vivo, as reported for pleomorphic adenomas of the parotid gland and metastatic carcinoma cells in ascites or pleural fluid, is still controversial. Here we report the co-expression of cytokeratins and vimentin in situ, in the parietal endoderm of the mouse embryo 8.5-13.5 days old. This population of individual, motile cells seems to be derived from a conventional epithelium by migration and differentiation. Our results support the idea that vimentin expression is specifically related to reduced cell-to-cell contact, and to the independent existence of a cell following detachment from an epithelial sheet.

Animals↗
PubMedDate not supplied

Mouse small eye results from mutations in a paired-like homeobox-containing gene.

Small eye (Sey) in mouse is a semidominant mutation which in the homozygous condition results in the complete lack of eyes and nasal primordia. On the basis of comparative mapping studies and on phenotypic similarities, Sey has been suggested to be homologous to congenital aniridia (lack of iris) in human. A candidate gene for the aniridia (AN) locus at 11p13 has been isolated by positional cloning and its sequence and that of the mouse homologue has been established (C.T., manuscript in preparation). This gene belongs to the paired-like class of developmental genes first described in Drosophila which contain two highly conserved motifs, the paired box and the homeobox. In vertebrates, genes which encode the single paired domain as well as those which express both motifs have been described as the Pax multigene family. A Pax gene recently described as Pax-6 is identical to the mouse homologue of the candidate aniridia gene. Here we report the analysis of three independent Sey alleles and show that indeed this gene is mutated and that the mutations would predictably interrupt gene function.

Alleles↗