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M Dziadek

Publications and source records attributed to M Dziadek.

67 records · Page 4Linked to original sources
PubMed1984

Laminin, proteoglycan, nidogen and collagen IV: structural models and molecular interactions.

Major components of basement membranes, including collagen IV, laminin, heparan sulphate proteoglycan and nidogen, were isolated from the matrix of the EHS sarcoma. The purified components were analysed for their domain structure and for the participation of distinct domains in molecular interactions and cell binding. Collagen IV consists of four domains which have triple helical or non-collagenous structures. Self-assembly of the protein into a network-like organization occurs by specific interactions between N-terminal triple helical segments and between the C-terminal globules. Cell binding requires a central triple helical segment. Laminin has the shape of an asymmetrical cross; different globular domains within this structure mediate binding to proteoglycan and to cells. The proteoglycan consists of four heparan sulphate chains attached to a small protein core. These chains have the potential to bind laminin, fibronectin and collagen IV. Nidogen was isolated in several molecular forms which showed either self-aggregation or binding to laminin.

Animals↗
PubMed1984

Ultrastructure and composition of connective tissue in hyalinosis cutis et mucosae skin.

Skin biopsies from a patient with hyalinosis cutis et mucosae (HCM) were studied by routine histology, electron microscopy, biochemical extractions, and immunofluorescence for extracellular matrix proteins. The upper dermis consisted of large hyaline regions mainly composed of noncollagenous proteins. A portion of this material was solubilized by reduction in 8 M urea. Anti-sera against these proteins revealed multiple antigens most of which were also detectable in normal skin. The hyaline regions showed a reduced content of collagens, particularly of thick fibrils and of fibronectin. The basal lamina around capillaries and at the dermal-epidermal junction appeared as multiple, concentric layers of amorphous laminae intercalated with thin collagen fibrils. They consisted of collagens type III and IV and of laminin as shown by immunofluorescence. Antibodies could also be raised against laminin of HCM skin which showed strong cross-reactions with authentic mouse laminin. Cultured fibroblasts from the HCM lesion showed increased synthesis of noncollagenous proteins at the expense of newly synthesized collagens. Some but not all of these noncollagenous proteins were also produced by fibroblasts from normal skin. The above data indicate that the hyaline material in HCM originates from the overproduction of noncollagenous proteins, most of which are normal constituents of human skin.

Adult↗
PubMed1983

Nidogen: a new, self-aggregating basement membrane protein.

Nidogen was purified from a mouse tumor basement membrane where it accounted for 2-3% of the total proteins. It was isolated as two forms (A and B) of a monomer (Mr = 80000) each consisting of a single polypeptide chain folded into a globular head connected to a small tail. The B form of the monomer was shown to be capable of aggregating into a nest-like structure (Mr greater than 250000). A smaller form (Mr = 45000) was observed in some of the extracts. The amino acid composition of nidogen was different to that of other basement membrane proteins. It contained about 10% carbohydrate, with N-linked and O-linked oligosaccharide chains in similar proportions. Isoelectrofocussing demonstrated a limited heterogeneity of nidogen with pI in the range 6.5 - 7. Monomeric nidogen failed to interact with other basement membrane components and heparin. Aggregation could be induced by limited proteolysis and was reversed by detergents or high salt concentrations. Together with the observation that most of the nidogen could be solubilized only after destroying the collagenous matrix, the data indicate that aggregation of nidogen reflects an activity involved in matrix assembly. Specific antibodies raised against nidogen did not distinguish between the monomeric and aggregated form of the protein but showed that the fragment was antigenically deficient. These antibodies did not cross-react with collagen type IV, laminin, entactin and heparansulfate proteoglycan. Immunofluorescence staining and absorption studies demonstrated that nidogen is a common component of authentic basement membranes. Larger forms of nidogen (Mr about 100000 and 150000) were found in organ cultures of Reichert's membrane suggesting that it is synthesized in precursor forms.

Animals↗
PubMed1982

Expression and methylation of the mouse alpha-fetoprotein gene in embryonic, adult, and neoplastic tissues.

Expression of the mouse alpha-fetoprotein gene in embryonic, adult, and neoplastic tissues was assessed by RNA dot hybridization using 32P-labeled alpha-fetoprotein cDNA as probe, alpha-fetoprotein mRNA was present in high levels in total RNA from yolk sac endoderm, fetal liver, and an alpha-fetoprotein-producing hepatoma. In contrast, this mRNA was greatly depleted in total RNA from yolk sac mesoderm and essentially absent in brain, adult liver, and a non-alpha-fetoprotein-producing hepatoma. These results indicated that alpha-fetoprotein gene expression was controlled primarily at the transcriptional level. The presence of the modified base, 5-methylcytosine, in the alpha-fetoprotein gene was studied by comparing hybridization patterns obtained by Southern blot analysis of DNA cleaved with the restriction endonuclease isoschizomers Msp I and Hpa II. The gross sequence organization and reiteration frequency of the alpha-fetoprotein gene were invariant among the DNA samples, whereas, in each case, there was a positive correlation between hypomethylation of six CCGG (Hpa II) sites in the alpha-fetoprotein gene and expression of this gene. These Hpa II sites were distributed throughout a large portion of the alp]a-fetoprotein gene. Patterns of cytosine methylation in this gene were established before day 15 of gestation in yolk sac endoderm and mesoderm.

Animals↗
PubMed1981

Quantitation and characterization of a species-specific and embryo stage-dependent 55-kilodalton phosphoprotein also present in cells transformed by simian virus 40.

A 55-kilodalton (kDal) protein was detected recently in primary cultures of day 12 mouse embryos by immunoprecipitation with serum from simian virus 40 (SV40) tumor-bearing hamsters (T serum), Preliminary evidence suggested that this protein was similar to a cellular 55-kDal protein induced after SV40 transformation of mouse cells. We now show that specific approximately 55-kDal [35S]methionine-labeled proteins precipitate from primary cultures of midgestation mouse, rat, and hamster embryos on addition of T serum or monoclonal antiserum prepared against the SV40-induced mouse 55-kDal proteins. The two-dimensional maps of the [35S]methionine-labeled tryptic peptides of the mouse, hamster, and rat embryo proteins are similar to the maps of the corresponding proteins from SV40-transformed cells. Primary cells from midgestation mouse, hamster, or rat embryos contain one-third to one-half as much 55-kDal protein as a SV40-transformed mouse fibroblast cell and nearly the same amount as F9 mouse embryonal carcinoma cells. The amount of 55-kDal protein is greatly reduced on replating the mouse, rat, or hamster embryo primary cells. The amount of this protein in mouse embryos is dependent on the stage of the embryo. The embryo proteins are phosphoproteins.

Animals↗
PubMed1979

Cell differentiation in isolated inner cell masses of mouse blastocysts in vitro: onset of specific gene expression.

Inner cell masses (ICMs) were isolated by immunosurgery from giant blastocysts formed by the aggregation of three morulae. A layer of endoderm cells formed on the outer surface of these primary ICMs in vitro. When this layer was removed by immunosurgery, a secondary endoderm layer formed. Alphafetoprotein (AFP) was used as a biochemical marker to characterize visceral endoderm formation in these cultured ICMs. The immunoperoxidase reaction on sections of ICMs cultured for intervals up to 120 h in vitro showed that some primary endoderm cells contained AFP, but these were always in the minority. The secondary endoderm layer, on the other hand, was composed of predominantly AFP-positive cells. It is concluded that the primary endoderm contains mainly parietal endoderm cells, while the secondary layer contains visceral endoderm cells. A model is proposed for the consecutive differentiation of parietal and visceral endoderm cell types from the ICM of mouse blastocysts.

Animals↗
PubMed1978

Localization and synthesis of alphafoetoprotein in post-implantation mouse embryos.

The localization and synthesis of alphafoetoprotein (AFP) during mouse embryogenesis were studied by immunoperoxidase and by immunoprecipitation after radioactive labelling, using an antiserum prepared against AFP. AFP is first detectable in embryos on the 7th day of gestation (7th day embryos). In 7th and 8th day embryos AFP is confined to visceral (proximal) endoderm cells around the embryonic region of the egg cylinder. Visceral extra-embryonic and parietal (distal) endoderm cells do not contain AFP. By the 9th day of gestation AFP is also present in the extra-embryonic ectoderm, mesoderm and embryonic ectoderm cells around the three cavities of the embryo. These tissues do not synthesize AFP when cultured in isolation, but can adsorb AFP when it is added to the medium. On the 12th day of gestation AFP synthesis is confined to the endoderm layer of the visceral yolk sac. It is concluded that the ability to synthesize AFP is a property which is restricted to the visceral endoderm during early post-implantation development. The presence of AFP in other tissues of the embryo appears to be due to adsorption.

Animals↗
PubMed1978

Modulation of alphafetoprotein synthesis in the early postimplantation mouse embryo.

The visceral endoderm of mouse egg cylinders on the 7th and 8th days of gestation is divided into the visceral embryonic (VE) endoderm cell population which synthesizes alphafetoprotein (AFP), and the visceral extra-embryonic (VEX) endoderm population which does not synthesize AFP. Embryonic (E) and extra-embryonic (EX) ectoderm and visceral endoderm tissues were enzymically separated, reassociated in different combinations, and cultured in vitro for 48 h. The immunoperoxidase reaction on sections of cultured tissues showed that both VE and VEX endoderm cells synthesize high levels of AFP when cultured in isolation or in association with E ectoderm, but do not synthesize AFP when in close association with EX ectoderm. Both 7th and 8th day VEX endoderm cells synthesize detectable levels of AFP 12 h after isolation, and contain high levels by 24 h. It is concluded that both VE and VEX endoderm cells have the ability to synthesize AFP, but modulation of expression occurs through an inhibitory influence of the EX ectoderm.

Animals↗
PubMed1977

An autoradiographic analysis of nucleic acid synthesis in the presumptive primordial germ cells of Xenopus laevis.

Microinjection of [3H]thymidine into Xenopus laevis embryos between late blastula (stage 10) and early tadpole (stage 44) showed that the presumptive primordial germ cells synthesis DNA between stages 10-33. The percentage of labelled cells was highest between stages 10 and 16, declined sharply between stages 22 and 26 and rose again between stages 26 and 33. The fluctuations in the labelling patterns together with increase in the number of presumptive primordial germ cells and direct observation of germ cells in mitosis suggested that the germ cells divide three times between stages 10 and 44. The first divisions probably take place during gastrulation (stages 10-12), the second relatively synchronously at about stages 22-24 and the third series again relatively synchronously about stages 37-39. This period of proliferative activity is distinguishable on the one hand from the cleavage divisions in which the number of germ cells does not increase and on the other hand from the next proliferative phase by a period of mitotic inactivity. Microinjection of [3H]uridine showed that the presumptive primordial germ cells synthesize RNA only in mid-gastrula to early tail-bud-stage embryos. There is no obvious simple causal relationship between RNA synthesis and the movement of the germ plasm to the nucleus, or with division of the germ cells or with their migration out of the endoderm.

Animals↗
PubMed1975

Mitosis in presumptive primordial germ cells in post-blastula embryos of Xenopus laevis.

In X. laevis embryos injected with (3-H) thymidine between early gastrula and late neurula, the presumptive primordial germ cell nuclei were labelled and some were observed in mitosis, confirming that division occurs throughout this developmental period. In all labelled and mitotic cells, the germ plasm adjoined the nucleus, an observation which invalidates the hypothesis that germ plasm inhibits mitosis in presumptive primordial germ cells after gastrula. In embryos which had been irradiated with UV at the vegetal pole at the 2-cell stage, the presumptive primordial germ cells also incorporated (3-H) thymidine and divided during the same developmental period.

Animals↗
PubMedDate not supplied

Extracellular matrix and its interactions in the diabetic kidney: a molecular biological approach.

Increased extracellular matrix (ECM) is the ultrastructural hallmark of diabetic microangiopathy. Its accumulation within the kidney is directly linked to the clinical manifestations of diabetic nephropathy, namely proteinuria and declining renal function. The pathogenesis of ECM changes in diabetes is not well understood, but is likely to involve interaction between cells, growth factors, structural proteins, and cell receptors for these molecules. Molecular biological techniques may offer the necessary tools for gaining insight into the pathogenetic processes that eventually lead to renal failure in diabetes.

Animals↗
PubMedDate not supplied

Differential expression of laminin, nidogen and collagen IV genes in the midgestation mouse placenta.

The distribution of laminin A, B1, B2, nidogen and collagen alpha 1(IV) mRNA was studied in the 12.5-day mouse placenta and uterus. This was compared to the pattern of laminin, nidogen and collagen IV immunoreactivity in the placenta at this time. High levels of B2 mRNA were distributed throughout the decidual layer, compared to lower levels of laminin B1, nidogen and collagen IV. In contrast, laminin B1 and nidogen mRNA were found at very high levels in the trophoblast giant cells and cytotrophoblast. Laminin B2 was much lower in trophoblast cells than in the decidua. Nidogen mRNA levels were low in the decidual cells, but high in endothelial cells lining the placental blood spaces in the decidual layer. Immunofluorescence staining of the placenta showed colocalization of laminin, nidogen and collagen IV in fetal and maternal layers of the placenta. In the antimesometrial area where the uterine epithelium was reforming laminin B1 and B2 mRNA were uniformly distributed between the epithelium and stroma, whereas nidogen and collagen alpha 1(IV) mRNA were only produced by the stromal cells. In all cell types, apart from parietal endoderm cells forming Reichert's membrane, laminin A chain mRNA was very low or absent. These results demonstrate that laminin and nidogen genes are not coordinately expressed in the midgestation mouse placenta. Comparison of the distribution of these mRNAs with collagen alpha 1(IV) mRNA suggests that different regions of the placenta produce specialized extracellular matrices which may contain different ratios of these polypeptides.

Animals↗