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PubMed1977

Mucopolysaccharide heterogeneity of the reptilian kidney basement membranes.

The kidney basement membranes of fifteen different reptiles from marine, terrestrial, desert, amphibious and fresh-water habitats have been analysed for their mucopolysaccharide contents histochemically, employing well-known and recent techniques. Capsular and tubular basement membranes possess only neutral mucopolysaccharides; on the other hand glomerular basement membrane possesses both neutral and acidic (sialic acid) mucopolysaccharides. The concentration of different mucopolysaccharides seems to be dependent on the type of habitat. Their possible physiological significance in the kidney function is discussed in great details.

Animals↗
PubMed1980

Capsular basement membrane alterations after tubulus atrophy and glomerulosclerosis in the dog kidney: contribution to the pathology of basement membrane genesis.

After K2HPO4 had been given to beagle dogs orally at a dose of 0.8 g/kg body weight for 14-38 weeks disseminated atrophy of the proximal tubule was apparent. As a result of this process glomerular alterations occur which develop via various stages of inflammation into glomerulosclerosis. Electron microscope findings of particular interest were obtained in the parietal epithelial cells and their basement membrane (BM). Ergastoplasma-rich epithelial cells often have organelle-free intracytoplasmic zones which contain solely microfilamentous and finely flocculent BM-like material. Such regions often appear lacuna-like and are sharply demarcated from the remaining cytoplasma. These areas are in close topographical contact with the parietal BM. The parietal epithelial cells make contact with the BM through dense bundles of filaments. These contacts resemble hemidesmosomes. We also found comparable relationships between epithelial cells and the BM in the proximal tubules. We are convinced that the conditions which we have described in the intracellular production of a material which is similar to the BM and the attachment of these areas onto the BM by filament bundles and hemidesmosomes represent sequestrations and extrusion of BM material. We believe that these could be pathological secretory processes of dedifferentiated epithelial cells.

Animals↗
PubMed1988

Immunogold quantitation of laminin, type IV collagen, and heparan sulfate proteoglycan in a variety of basement membranes.

A series of basement membranes was immunolabeled for laminin, type IV collagen, and heparan sulfate proteoglycan in the hope of comparing the content of these substances. The basement membranes, including thin ones (less than 0.3 micron) from kidney, colon, enamel organ, and vas deferens, and thick ones (greater than 2 micron), i.e., Reichert's membrane, Descemet's membrane, and EHS tumor matrix, were fixed in formaldehyde, embedded in Lowicryl, and treated with specific antisera or antibodies followed by anti-rabbit immunoglobulin bound to gold. The density of gold particles, expressed per micron2, was negligible in controls (less than or equal to 1.1), but averaged 307, 146, and 23, respectively, for laminin, collagen IV, and proteoglycan over the thick basement membranes (except for Descemet's membranes, over which the density was 16, 5, and 34, respectively) and 117, 72, and 64, respectively, over the lamina densa of the thin basement membranes. Lower but significant reactions were observed over the lamina lucida. Interpretation of the gold particle densities was based on (a) the similarity between the ultrastructure of most thick basement membranes and of the lamina densa of most thin basement membranes, and (b) the biochemical content of the three substances under study in the EHS tumor matrix (Eur J Biochem 143:145, 1984). It was proposed that thick basement membranes (except Descemet's) contained more laminin and collagen IV but less heparan sulfate proteoglycan than the lamina densa of thin basement membranes. In the latter, there was a fair variation from tissue to tissue, but a tendency towards a similar molar content of the three substances.

Animals↗
PubMed1980

Comparison of the chemical and polypeptide composition of tubular and glomerular basement membranes.

Renal tubular and glomerular basement membranes were isolated from rabbit, rat and mouse kidneys. Methods were developed to obtain the basement membrane from limited numbers of animals. Rabbit and mouse tubular basement membrane as well as rabbit and rat glomerular basement membrane were obtained from single animals in quantities sufficient for electrophoresis and chemical analysis. The chemical composition of all the basement membranes were compared and sodium dodecylsulfate-polyacrylamide gel electrophoresis was performed on rabbit tubular and glomerular basement membranes in order to compare their polypeptide composition. The chemical composition of the tubular basement membranes were similar, each species having nearly equal concentrations of glycine, hydroxyproline and hydroxylysine, respectively. Glomerular basement membranes were also similar to each other and close to tubular basement membranes in chemical composition. Within each species, the glycine, hydroxyproline and hydroxylysine values for tubular basement membrane were about 10% higher than for glomerular basement membrane. The polypeptide composition of a reduced, sodium dodecylsulfate-soluble fraction of the rabbit basement membranes appeared to be alike with two exceptions. A prominent band of Mr = 160,000 seen in gels of tubular basement membrane was present as a lightly staining band in glomerular basement membrane samples and a prominent band of Mr = 140,000 in gels of glomerular basement membrane was seen as a light band in samples of tubular basement membrane.

Animals↗
PubMed1990

A non-mammalian in vivo model for cellular and molecular analysis of glucose-mediated thickening of basement membranes.

An increase of basement membrane thickness in renal glomeruli, blood vessels, and other tissues is a consistent pathological observation in individuals with diabetes mellitus. Although a number of pathological complications of the disease are thought to result from this structural abnormality in basement membranes, the mechanism(s) responsible for this glucose-mediated process remain unknown. The current study was designed to develop a non-mammalian in vivo epithelial/basement membrane model which would facilitate detailed analysis of the cellular and molecular processes which lead to thickening of basement membrane under hyperglycaemic conditions. The system developed utilizes the Cnidarian, Hydra vulgaris. Hydra lends itself to such studies because of (1) its simplified body structure which is composed of an epithelial bilayer with an intervening basement membrane (mesoglea) and (2) its extensive regenerative capacity which allows cell pellets (Hydra cell aggregates), formed from isolated Hydra cells, to develop into adult Hydra within 72-96 h. This process involves reformation of an epithelial bilayer and de novo biosynthesis of a basement membrane. Our studies indicate that exposure of developing Hydra cell aggregates to levels of D-glucose which mimic that observed in the human diabetic patient (15 mmol/l) induces a doubling of Hydra basement membrane thickness within 72-96 h of pellet formation. The same results were obtained using 15 mmol/l D-Ribose which is a highly efficient glycating agent. The data presented support the use of the Hydra cell aggregate system as a potentially powerful non-mammalian in vivo model to investigate the cellular and molecular mechanism(s) underlying glucose-mediated basement membrane thickening.

Animals↗
PubMed1993

Basement membrane proteoglycans and development.

Basement membranes contain distinct collagen, glycoprotein and proteoglycan species, and these exhibit considerable heterogeneity in isoform or type when different tissue types are compared. Additionally, many components are differentially expressed in organogenesis. We have considered the distributions in glomerulogenesis of two distinct basement membrane proteoglycans, a small heparan sulfate proteoglycan and a chondroitin sulfate proteoglycan (BM-CSPG). While the former was present in all kidney basement membranes through development, the latter was apparently regulated in distribution. BM-CSPG was only strongly expressed in the vasculature invading late comma stage glomeruli, and later in presumptive and mature Bowman's capsule. Over the first six to eight weeks, the capillary basement membranes contained BM-CSPG, but in gradually decreasing amounts until it became completely undetectable. The basement membrane of the adult rat glomerulus is unique in its lack of BM-CSPG. However, in diabetic rats, BM-CSPG is apparently re-expressed in the glomerular basement membrane, a potential marker for pathological changes in glomerular structure. While its function awaits elucidation, BM-CSPG may be essential for basement membrane integrity or stability and have important roles in kidney development.

Animals↗
PubMed1981

Structural components and characteristics of Reichert's membrane, an extra-embryonic basement membrane.

This paper presents an analysis of mouse and rat Reichert's membrane, a thick basement membrane formed between the trophoblast and parietal endoderm cells of early mammalian embryos. When analyzed by polyacrylamide gel electrophoresis. Reichert's membranes from rat and mouse conceptuses appear simple and consist primarily of collagen and 4 noncollagenous glycoproteins of approximate Mr = 415,000, 245,000, 170,000, and 50,000. The proteins at 415,000 and 245,000 are similar in molecular weight to laminin and are immunoprecipitated by anti-laminin antiserum. The protein at 170,000 is co-precipitated with laminin and represents a novel form of a laminin-like protein, whereas the protein at 50,000 is unrelated to laminin. Using metabolic labeling experiments, it is shown that parietal endoderm cells synthesize these components and incorporate them into the matrix in organ cultures but do not degrade Reichert's membrane in the conditions used over a 6-day culture period. Evidence is presented that the high molecular weight collagenase-sensitive proteins (greater than 420,000) observed on polyacrylamide gel electrophoresis are due to lysyl oxidase-derived cross-links between Reichert's membrane components.

Animals↗
PubMed1993

Laminin distribution in developing glomerular basement membranes.

The renal glomerular basement membrane (GMB) separates two distinctly different cell layers: the vascular endothelium, and visceral epithelial podocytes. When initial vascularization of the forming glomerulus takes place during nephrogenesis, the early GBM forms by fusion of a dual basement membrane between endothelial cells and podocytes. As glomerular capillary loops blossom, newly synthesized basement membrane segments derived from podocytes are then inserted or spliced into the fused GBM. The molecular processes accounting for either basement membrane fusion or splicing are unresolved. Using monoclonal anti-mouse laminin antibodies (mAbs) against the end of the laminin long arm (5D3), we have shown in adult mice that peripheral loop GBM is only weakly immunoreactive but the mesangial matrix and tubular basement membrane (TBM) is intensely positive. In contrast, mAbs against domains in the center of the laminin cross only label TBMs and mesangial matrices of mature mice and GBMs are negative. Immunofluorescence microscopy of neonatal mouse kidneys showed, however, that anti-laminin mAbs brightly labeled developing GBMs of glomeruli undergoing initial vascularization and capillary loop formation. Post-fusion GBMs of maturing stage glomeruli became unreactive for most anti-laminin mAbs but remained positive for 5D3. Our results therefore show that some GBM laminin epitopes are transiently expressed during glomerular development. These changes in GBM immunoreactivities may reflect proteolytic processing during basement membrane fusion and splicing, or temporally controlled synthesis of different laminin isoforms.

Animals↗
PubMed1978

Cellular reactivity to altered glomerular basement membrane in glomerulonephritis.

Glomerular basement membrane may be altered during glomerulonephritis, exposing antigens that are recognized as foreign. Immunochemical studies suggest that removal of peripheral glycopeptides from the basement membrane with glycosidase mimics this pathogenetic event. To examine these hypotheses, we studied 24 patients with biopsy-proved glomerulonephritis by means of the lymphocyte-blast-transformation assay. Three preparations of normal glomerular basement membrane were used: two mimicked the native state for the peripheral glycopeptides, and one was altered by glycosidases. Results showed minimal differences in responses to native glomerular basement-membrane preparations among patients with glomerulonephritis and control groups. However, patients with glomerulonephritis had a significant blastogenic response to the glycosidase-treated glomerular basement membrane as compared to patients with nonglomerular renal disease and normal controls (P less than 0.0005). These studies suggest that cellular reactivity to altered glomerular basement-membrane antigens can be detected in certain forms of progressive glomerulonephritis.

Antigens↗
PubMed1984

[Basement membranes--structure, function, pathology].

Basement membranes are extracellular structures with a heterogeneous molecular composition. Several components have been identified and could be localized in specific morphological structures. Type IV collagen is found in the lamina densa, whereas laminin is the major component of the lamina lucida. Small amounts of heparan sulfate proteoglycan are also present in the lamina lucida. In some basement membranes, fibronectin and another glycoprotein, nidogen, could be identified. Epidermal basement membranes contain, in addition, the bullous pemphigoid antigen. Basement membranes are involved in several diseases and play an important part in tumor progression. Antibodies against distinct components of basement membranes have been shown to be useful as diagnostic tools in bullous disorders (e.g., epidermolysis bullosa) and for identifying the extracellular matrix of skin tumors (e.g., neurofibroma, cylindroma, granular cell myoblastoma).

Basement Membrane↗
PubMedDate not supplied

Laminin and fibronectin content of mouse glomerular and tubular basement membrane.

Because the glomerular basement membrane (GBM) is subject to damage in a multitude of renal diseases, a model of basement membrane permeability properties would be useful for learning more about this important barrier. Isolated, perfused tubular basement membrane (TBM) allows measurement of permeability, but it is not known whether TBM is similar enough to GBM for data to be extrapolated from this model to the glomerulus. As a first approach to assessing differences between GBM and TBM, we looked at composition. Renal glomeruli and tubules were isolated from Swiss-Webster mice by sucrose-gradient centrifugation. GBM and TBM were isolated by sonication in 1% deoxycholate and then subjected to a sequential extraction procedure. Analysis of the solubilized basement membranes by electrophoresis revealed a complex mixture of proteins. Immunoblot analysis demonstrated that, among the proteins, laminin and fibronectin were found exclusively in the guanidine and guanidine/dithiotreitol extracts. The total amount of laminin extracted in GBM, 1.8 +/- 0.001 micrograms/mg dry weight (n = 2 groups animals, by inhibitory ELISA), was significantly less than in TBM, 3.4 +/- 0.1 micrograms/mg dry weight (n = 2); however, the total amount of fibronectin extracted did not differ between GBM and TBM, 8.2 +/- 0.8 and 7.7 +/- 1.0 micrograms/mg dry weight (n = 2) respectively. Examination of deoxycholate supernatants was carried out to see if components of GBM or TBM were solubilized during isolation of basement membranes. Immunoblot analysis revealed loss of some laminin and fibronectin occurred during the detergent isolation of GBM and TBM. We conclude that GBM and TBM are qualitatively similar in that they have the same protein components, but differ significantly in content of laminin and probably other macromolecular components.

Animals↗
PubMed1990

Distribution of Goodpasture antigens within various human basement membranes.

Collagenase-digested basement-membrane preparations from human kidney glomeruli, kidney tubules, lung, choroid plexus, aorta, intestine, and placenta were analysed according to their reactivity to anti-glomerular basement membrane (anti-GBM) antibody-positive Goodpasture sera. Sodium dodecylsulphate polyacryl gel electrophoresis (SDS-PAGE), and immunoblotting were performed after antigen enrichment by passage of the collagenase digests through an anion-exchange column. Reactivity of anti-GBM antibodies with one to three monomers (24, 26 and 28 kD) and two dimers (44 and 50 kD) were demonstrated in basement membrane preparations of kidney glomeruli, kidney tubules, lung, placenta, and aorta. In basement membranes of choroid plexus reactivity with only the 28 kD monomer and the 50 kD dimer were identified. In intestinal basement membrane, reactivity was restricted to the 50 kD dimer. Analysis of the amounts of Goodpasture antigen by inhibition ELISA demonstrated that the highest concentration were in glomerular basement membrane, while the lowest were found in aortic basement membrane. The results indicate that Goodpasture antigens are common to all the basement membranes investigated. The differences in antigen concentration and in reactivity on immunoblotting may indicate different antigen amounts, a heterogeneity of collagen IV within the various basement membranes, or differences in antigen accessibility within the membranes. We conclude that the primary clinical restriction of the anti-GBM disease to lungs and kidneys is not explained by a preservation of the antigen to this basement membrane. Rather, the clinical pattern may be influenced by differences in the molecular composition of the basement membranes as well as by non-immunological mechanisms.

Anti-Glomerular Basement Membrane Disease↗
PubMed2005

Pathology of thin basement membrane nephropathy.

Thin basement membrane nephropathy (TBMN) is a glomerular disorder characterized clinically by isolated hematuria and pathologically by diffuse thinning of the glomerular basement membrane (GBM) on ultrastructural examination. The pathologic diagnosis of TBMN is problematic, in part because of the wide range of GBM thicknesses in the normal population. GBM thickness varies with age, sex, and the different methods of tissue preparation and measurement. In addition, there are no standardized diagnostic criteria defining the degree or extent of GBM thinning required for the diagnosis of TBMN. GBM thinning is often seen in other glomerulopathies, where it may represent an overlap with TBMN or may be secondary to GBM damage and remodeling. Importantly, TBMN must be differentiated from the GBM thinning seen in some renal biopsy specimens from boys and female heterozygotes with X-linked Alport syndrome because of the very different prognoses of these two conditions.

Basement Membrane↗