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Biomedical subjects

B L Hogan

Publications and source records attributed to B L Hogan.

At least 163 records · Page 9Linked to original sources
PubMed1985

Chromosomal assignments of the genes coding for human types II, III, and IV collagen: a dispersed gene family.

The human type II collagen gene, COL2A1, has been assigned to chromosome 12, the type III gene, COL3A1, to chromosome 2, and one of the type IV genes, COL4A1, to chromosome 13. These assignments were made by using cloned genes as probes on Southern blots of DNA from a panel of mouse/human somatic cell hybrids. The two genes of type I collagen, COL1A1 and COL2A1, have been mapped previously to chromosomes 17 and 7, respectively. This family of conserved genes seems therefore to be dispersed throughout the genome.

Animals↗
PubMed1985

Expression of c-fos in parietal endoderm, amnion and differentiating F9 teratocarcinoma cells.

The expression of the cellular proto-oncogene, c-fos, in extra-embryonic tissues of the mouse was investigated using a v-fos DNA probe and an affinity-purified antiserum raised against a C-terminal synthetic peptide. At 13.5 days of development, parietal endoderm--a tissue not previously studied using these methods--was found to express c-fos RNA at a higher level than the amnion or placenta. The previously reported dramatic increase in c-fos RNA levels in extra-embryonic membranes during gestation was found to be confined to the amnion. The antipeptide serum specifically recovered proteins with Mr values of 46,000 and 39,000 from extracts of parietal endoderm and amnion cells labelled for 15 min with 35S-methionine. On sodium-dodecyl-sulphate/polyacrylamide gel electrophoresis these proteins co-migrated with proteins immunoprecipitated using serum from rats inoculated with FBJ-MuSV-transformed cells (tumour-bearing rat serum). Pulse-chasing and 32P-labelling experiments showed that the protein with an Mr of 46,000 was rapidly converted into higher-molecular-weight phosphorylated derivatives. F9 teratocarcinoma stem cells differentiated into parietal-endoderm-like cells in response to treatment with retinoic acid and dibutyryl cyclic AMP. However, this differentiation was not accompanied by any large transient increase in c-fos RNA expression.

Amnion↗
PubMed1984

Cell surface-associated proteins which bind native type IV collagen or gelatin.

Gelatin coupled to Sepharose has been used to isolate [35S]methionine-labeled polypeptides of Mr = 47,000, 56,000, 62,000, and 65,000 from the 12,000 X g supernatant of detergent extracts of mouse embryo parietal endoderm cells. The polypeptides can also be recovered from various established cell lines which synthesize type IV procollagen, and in these cells the Mr = 47,000 polypeptide is the major gelatin-binding component. Several lines of evidence, including the results of continuous labeling and pulse-chase experiments, show that the polypeptides are not derived by proteolytic cleavage of larger precursors and are distinct from fragments of fibronectin. The Mr = 47,000, 62,000, and 65,000 polypeptides all contain N-linked oligosaccharide side chains, as judged by their labeling with [3H]mannose and their sensitivity to tunicamycin. The Mr = 62,000 and 65,000 polypeptides can be resolved by two-dimensional gel electrophoresis into species with different isoelectric points, and the Mr = 47,000 has a pI of 7.5-8.0. None of the gelatin-binding polypeptides appear to accumulate in the culture medium, and the Mr = 47,000, 62,000, and 65,000 species are labeled in a lactoperoxidase-catalyzed iodination of intact cells, suggesting that they are associated with the cell surface. Only the Mr = 47,000 glycoprotein binds to native type IV collagen. Possible functions for these surface components in vivo are discussed.

Animals↗
PubMed1984

Reichert's membrane as a model for studying the biosynthesis and assembly of basement membrane components.

The major components of Reichert's membrane (laminin, type IV procollagen, entactin and heparan sulphate proteoglycan) are all synthesized by the parietal endoderm cells of the mouse embryo. Fibronectin is found mainly on the trophoblast side of Reichert's membrane and does not appear to be a major structural component. Parietal endoderm cells are thought to differentiate and migrate as individual cells from the margins of the epithelial visceral endoderm layer. They may interact with the type IV collagen in Reichert's membrane via a surface-associated protein of Mr = 47000 known as 'colligin'. Parietal endoderm cells are a rich source of mRNAs for basement membrane components and have been used to prepare a cDNA library in the expression vectors pUC8 and pUC9 from which cDNAs for type IV collagen and laminin B chains have been isolated.

Animals↗
PubMed1984

Pattern of serum protein gene expression in mouse visceral yolk sac and foetal liver.

We have shown by molecular hybridisation that the mRNAs for albumin, transferrin, apolipoprotein-A1, and alpha 1-antitrypsin are expressed at high levels in mouse visceral yolk sac. In contrast, the mRNAs for contrapsin (a plasma protease inhibitor) and the major urinary proteins (MUPs) are not detected in the visceral yolk sac at any stage of embryonic development. Contrapsin and MUP mRNAs both appear late in liver development. These differences in expression suggest that the visceral yolk sac is more similar to the foetal than adult mouse liver in its pattern of gene expression. However, the developmental time course of expression of these mRNAs is different between the foetal liver and the yolk sac. Evidence is also presented that the visceral yolk sac synthesises and secretes other apolipoproteins in addition to apolipoprotein-A1. These results suggest that the visceral yolk sac and foetal liver, two tissues with different embryological lineages, perform similar functions but are independently programmed for expression of the same set of serum protein genes.

Animals↗
PubMed1984

Sequencing of laminin B chain cDNAs reveals C-terminal regions of coiled-coil alpha-helix.

cDNAs for laminin B chains have been isolated from a parietal endoderm cDNA library in pUC8 and pUC9. Identification is based on: ability to direct the synthesis in Escherichia coli of polypeptides carrying laminin antigen determinants, in vitro translation of hybrid selected mRNA, and hybridization to high mol. wt. RNA differentially expressed in cells synthesizing large amounts of laminin. The plasmid pPE9 hybrid selects mRNA for the B2 (mol. wt. 185 000) chain and provides 217 residues of C-terminal amino acid sequence. The plasmids pPE386 and 49 both hybrid select mRNAs for the B1a (mol. wt. 205 000) and B1b (mol. wt. 200 000) chains. These two cDNAs are identical over much of their sequence, but pPE386 includes 133 nucleotides of 3' non-coding sequence and a poly(A) tail. Together they provide 495 residues of C-terminal amino acid sequence. Analysis of the predicted sequences reveals a striking heptad repeat, with a high probability that residues a and d are hydrophobic. Such a repeat is typical of the coiled-coil alpha-helices found in proteins such as myosin, tropomyosin and desmin (2-stranded) and fibrinogen (3-stranded).

Amino Acid Sequence↗
PubMed1984

A scanning electron microscope study of the extraembryonic endoderm of the 8th-day mouse embryo.

Late primitive streak embryos were dissected to reveal the junction between the visceral (VE) and parietal (PE) extraembryonic endoderm. Scanning electron microscopy showed that the two cell types differ markedly in their surface morphology and intercellular organization: the VE cells have numerous apical microvilli and form part of a continuous epithelial layer, while the smoother PE cells are scattered individually over the surface of Reichert's membrane. One interpretation of the morphology of the junction between the two tissues is that visceral endoderm cells in this region are detaching from the epithelial layer, migrating on to Reichert's membrane and differentiating into parietal endoderm. Preparatory to this, the visceral endoderm cells in the junctional zone may undergo extensive reorganization of their surface membranes.

Animals↗
PubMed1984

Expression of EGF receptor and transferrin by F9 and PC13 teratocarcinoma cells.

We document the time of appearance and the levels of two markers of differentiation during the formation of embryoid bodies by two embryonal carcinoma (EC) cell lines. Neither of these markers has been described before for EC cells differentiating in aggregate culture, and they further extend the identification and characterization of new cell types. Both F9 and PC13 EC cell lines form embryoid bodies (so-called because they resemble early mouse embryos) with an outer epithelial layer of visceral endoderm cells, after suspension culture in the presence of retinoic acid. However, the two cell lines differ in the procedures needed to initiate the differentiation process. Once floating aggregate cultures have been formed, the time course of the appearance of epidermal growth factor (EGF) receptors and of the secretion of transferrin are similar in both cell lines, although the levels differ. EGF receptors and transferrin are quantified by 125I-EGF binding assays and enzyme-linked immunosorbent assays (ELISA) using specific antibodies, respectively. The expression of EGF receptors increases about two fold while that of transferrin increases up to 40 fold after treating F9 aggregates with retinoic acid. The EGF receptors reach a maximum 4 days after adding retinoic acid and then decline, while transferrin only increases later from a low but detectable level. For PC13 cells, EGF receptors increase tenfold, and transferrin synthetic rate increases 40 fold during the time-course. Interestingly, unstimulated F9 cells in monolayer cultures also express low levels of these markers, while the levels in PC13 EC cells are barely detectable above background.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Isolation of cDNA clones for basal lamina components: type IV procollagen.

We have isolated cDNA clones for mouse type IV procollagen from a library constructed from total poly A+RNA of 13.5 day mouse embryo parietal endoderm (PE) cells. In Northern analysis these clones hybridise to a 6.8 kb RNA which is abundant in embryonic PE cells and in differentiated F9 teratocarcinoma cells. Hybrid selection and in vitro translation of the cDNA specific mRNA produced a single polypeptide of Mr = 165 000. This polypeptide was specifically immunoprecipitated with mouse type IV procollagen antisera and comigrated on SDS-gel electrophoresis with one of the two in vitro synthesised chains of type IV procollagen. Undifferentiated F9 teratocarcinoma cells can be induced by retinoic acid and dibutyryl cAMP to differentiate in vitro into endoderm-like cells which resemble mouse PE cells in synthesising large amounts of basement membrane proteins, including type IV procollagen. Here we show, using one of the cDNA clones as a probe for type IV procollagen, that an increase in cellular concentration of type IV procollagen mRNA occurs within 24 to 48 hours of induction, reaching a constant high level by 72 hours.

Animals↗
PubMed1983

In vitro synthesis of laminin and entactin polypeptides.

Total RNA and poly(A+) RNA, isolated from 13.5-day-old mouse embryo parietal endoderm cells and from differentiated F9 teratocarcinoma cells that synthesize laminin and entactin, were translated in the reticulocyte lysate. Antiserum raised against purified and denatured laminin B chains specifically immunoprecipitated from the translation reaction polypeptides of Mr = 205,000, 200,000, and 185,000. Antiserum against the native complex of laminin and entactin also immunoprecipitated these polypeptides, although less efficiently. In addition, this antiserum immunoprecipitated polypeptides of Mr = 300,000, 270,000, and 140,000. Antiserum against purified and denatured entactin immunoprecipitated only the Mr = 140,000 polypeptide. In contrast, no polypeptides were immunoprecipitated from translation reactions programmed with RNA from undifferentiated F9 cells that produce only small amounts of laminin and entactin. The in vitro synthesized polypeptides migrate on NaDodSO4-polyacrylamide gel electrophoresis slower than the respective unglycosylated laminin and entactin chains isolated from cells treated with tunicamycin. Supplementing the reticulocyte lysate with dog pancreas microsomal membranes yields in vitro translation products which co-migrate with the respective glycosylated laminin and entactin chains of control cells. Taken together, these results suggest that the polypeptides described represent in vitro synthesized laminin and entactin chains.

Animals↗
PubMed1983

Changes in the rate of laminin and entactin synthesis in F9 embryonal carcinoma cells treated with retinoic acid and cyclic amp.

The synthesis of laminin A and B chains, and of entactin, has been measured in murine F9 embryonal carcinoma cells differentiating in response to retinoic acid and cyclic AMP. Undifferentiated cells synthesis low levels of laminin, amounting to approximately 0.02% of the [35S]methionine incorporated into cytoplasmic protein during a 15-min pulse. After 6 days induction, laminin synthesis has increased 15- to 20-fold. Undifferentiated F9 cells synthesise more intracellular laminin B2 chains (Mr 225,000) than B1 chains (Mr 225,000), but the excess B2 chains are apparently not assembled into the secreted laminin molecule. Indirect immunofluorescence shows faint cytoplasmic staining and short fibrils of laminin between the undifferentiated F9 cells.

1-Methyl-3-isobutylxanthine↗
PubMed1982

In vitro synthesis of type IV procollagen.

Total RNA was isolated from parietal endoderm cells of 131/2-day mouse embryos that synthesize large amounts of type IV procollagen. In vitro translation of this RNA in the reticulocyte lysate supplemented with a ribonuclease inhibitor yielded two equally prominent polypeptides of Mr = 165,000 and 168,000, immunoprecipitable with anti-mouse type IV collagen serum. The Mr = 165,000 polypeptide was shown by one-dimensional peptide mapping to represent an unmodified chain of type IV procollagen. The Mr = 168,000 polypeptide, the in vitro synthesis of which was barely detectable in the absence of a ribonuclease inhibitor, most likely represents the other genetically distinct chain of type IV procollagen. Similar results to those described were also obtained using poly(A) + RNA prepared from murine F9 embryonal carcinoma cells induced to differentiate in vitro into parietal endoderm.

Animals↗
PubMed1982

Localization of fibronectin, laminin-entactin, and entactin in Reichert's membrane by immunoelectron microscopy.

Immunoelectron microscopy using protein A-colloidal gold complexes of different sizes was used to study the relative distribution of extracellular matrix glycoproteins within Reichert's membrane (RM) of 13.5-day mouse embryos. Labelling for fibronectin was distributed asymmetrically; the highest concentration occurring in the outermost layer adjacent to the trophoblast cells and negligible labelling in the inner matrix, beneath the parietal endoderm cells. Within the main body of the membrane, fibronectin was concentrated in discrete electron-opaque deposits. Antibodies raised against the native complex between laminin and entactin , and against entactin alone labelled the RM more uniformly.

Animals↗
PubMed1982

Synthesis and localization of two sulphated glycoproteins associated with basement membranes and the extracellular matrix.

Two sulphated glycoproteins (sgps) of apparent molecular weight (Mr) 180,000 and 150,000, are synthesized by murine PYS and PF HR9 parietal endoderm and Swiss 3T3 cells. The Mr 150,000 sgp has a similar chemical structure to the sulphated glycoprotein, C, synthesized and laid down in Reichert's membrane by mouse embryo parietal endoderm cells (Hogan, B. L.M., A. Taylor, and A.R. Cooper, 1982, Dev. Biol., 90:210-214). Both the Mr 180,000 and 150,000 sgps are deposited in the detergent-insoluble matrix of cultured cells, but they do not apparently undergo any disulphide-dependent intermolecular interactions and are not precursors or products of each other. They contain asparagine-linked oligosaccharides, but these are not the exclusive sites of sulphate labeling. Antiserum raised against the Mr 150,000 sgp C of Reichert's membranes has been used in an immunohistochemical analysis of rat skin. In early foetal and adult skin the antigen is present only in basement membranes, but transiently before and after birth it is also found throughout the upper part of the dermis. This suggests that 150,000 sgp C is at times synthesized by nonepithelial cells and contributes to the extracellular matrix of mesenchymal tissues.

Animals↗