Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033687 (proteinuria)
 24,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Immunoblots of several urinary low-molecular-mass proteins can be very useful in investigations of pathological proteinuria. However, use of certain commercial antisera in such procedures leads to artifacts corresponding to nonspecific bands; e.g., immunoglobulins from nonimmunized rabbit serum may bind to human urinary proteins, and this binding is not inhibited by Triton X-100. We have developed a procedure to improve the specificity of detection of urinary low-Mr proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, by immunoblotting with commercial antisera: we treat the protein blot with a mixture of mercaptoethanol and sodium dodecyl sulfate before incubation with the first antiserum. This allows direct use of commercial antisera without prior absorption of contaminating antibodies.
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PMID:Reducing the artifacts produced by impure antisera in immunoblots of low-molecular-mass proteins in urine. 242 44

Heymann nephritis (HN) is an experimentally induced glomerulonephropathy of the rat characterized by subepithelial immune deposits and proteinuria. Immunization with a complex multimeric glycoprotein, gp600, comprising four subunits gp330, gp140, gp110, and gp70 has been shown to induce the complete form of the disease including proteinuria. Examination of three different batches of heterologous anti-gp600 antisera by immunoblot technique showed that the reactivity toward gp70 was dominant and common to all three antisera. gp70 was isolated from Triton X-100-solubilized Fx1A by lectin Lens culinaris affinity chromatography, and the purity was confirmed by SDS-PAGE. Ten rats were actively immunized with 200 micrograms of gp70. All 10 animals developed circulating brush border antibody and typical granular IgG deposits in the glomerulus but only 1/10 animals developed abnormal proteinuria. A potent antiserum against gp70 was prepared in the rabbit. It reacted strongly to the glomerular capillary wall and the proximal tubular brush border by immunofluorescence. By Protein A immunogold technique using anti-gp70, gold particles were found associated with the glomerular basement membrane (GBM)-endothelial region. By immunoblot analysis of rat GBM using the same anti-gp70 antiserum, a 70-kDa cross-reactive antigen was demonstrated in GBM preparations. These results show that the smallest subunit, gp70 of the complete HN antigen, gp600/Fx1A can independently induce the lesion of HN, but without proteinuria. The presence of gp70 on the endothelial side of the GBM is consistent with a role for in situ antigen-antibody reactions at sites other than the subepithelial region in the pathogenesis of HN.
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PMID:Nephritogenicity and immunocytochemical localization of the 70-kilodalton glycoprotein subunit (gp70) of Heymann antigen. 328 3

Passive Heymann nephritis with acute and severe proteinuria was produced in rats by a single injection of heterologous antibody against a purified glycoprotein which consisted of homologous subunits with a molecular weight of 108,000 (gp108). Gp108 was identified as one of the major antigens in rat renal tubular fraction (FX1A) on immunoblotting assay by using total proteins of FX1A and rabbit antiserum against FX1A. A band of gp330, which was identified as a pathogenic antigen of Heymann nephritis by Kerjaschki D and Farquhar MG (Proc Natl Acad Sci USA 79:5557, 1982) was detected as another band by Coomassie blue staining and immunoblotting. Autoantibodies in the sera of FX1A-injected (active Heymann nephritis) rats reacted to the band of gp330 but not to gp108. These results indicate that gp108 is a different glycoprotein from both gp330 and its degradation products. GP108 was subsequently purified to near homogeneity by extraction with Triton X-100, and then DEAE-cellulose and Bio-Gel A-1.5m column chromatographies. On gel permeation chromatography, the purified antigen showed a molecular weight of 310,000, suggesting that it consists of dimer or trimer of gp108. Rabbits immunized with gp108 produced an antibody which showed monospecific binding to gp108. The antibody stained with brush border of proximal renal tubules in addition to the capillary loops in rat glomeruli by indirect immunofluorescence. Injection of rabbit antiserum against gp108 in rats induced severe proteinuria within 2 days. On the 2nd day after the injection, the glomeruli of the animals showed granular immune deposits along the capillary loops in addition to dominant staining of the brush border of the proximal tubules by immunofluorescence. These results indicate that gp108 is a pathogenic antigen in passive Heymann nephritis and that an antibody against gp108 has a nephritogenic and proteinuria-inducing activity.
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PMID:Passive Heymann nephritis with acute and severe proteinuria induced by heterologous antibody against renal tubular brush border glycoprotein gp108. 375 92

Several lines of evidence suggest that increased neuraminidase activity may be responsible for the loss of glomerular N-acetylneuraminic acid (AcNeu) observed in various glomerular diseases. However, virtually no information is available on the activity of neuraminidase in glomeruli or the potential role of this enzyme in glomerular pathophysiology. Utilizing 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid (4MU-AcNeu) as substrate, we defined optimal assay conditions and characterized neuraminidase activity in glomeruli and, for comparison, in other renal fractions and liver. Neuraminidase activity in glomeruli, cortex and tubules was maximal at pH 4.4. The Km for 4MU-AcNeu was estimated to be 195 microM for glomeruli and 226 microM for cortex. Glomerular neuraminidase was inhibited by AcNeu (90% at 25 mM) and high concentrations of Triton X-100 (26% at 0.5%), but unaffected by CaCl2, EDTA or N-ethylmaleimide (each 1 mM). Neuraminidase activity (nmol/h per mg of protein; mean +/- S.E.M.) in normal rat kidney was: cortex, 14.47 +/- 0.76; medulla, 7.85 +/- 0.64; papilla, 2.64 +/- 0.11; tubules, 13.79 +/- 0.70; glomeruli, 5.57 +/- 0.28. In comparison, neuraminidase activity in rat liver was 2.58 +/- 0.14. Puromycin aminonucleoside (PAN)-induced nephrotic syndrome is a model of glomerular disease in which the loss of glomerular AcNeu is well documented. In two separate studies, we observed no change in the specific activity of neuraminidase in either glomeruli or cortex isolated from rats treated with PAN (15 mg/100 g, intraperitoneally) and killed at either the onset or the peak of proteinuria. Results were similar whether neuraminidase activity was expressed per mg of protein or per microgram of DNA.
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PMID:Renal neuraminidase. Characterization in normal rat kidney and measurement in experimentally induced nephrotic syndrome. 382 21

Protectin (CD59) is a low molecular weight glycophosphoinositol-anchored inhibitor of the membrane attack complex of complement (MAC) that is present, for example, on the membranes of endothelial cells and on epithelial cells of glomeruli and distal tubuli. To examine for the possibility that CD59 becomes detached from cell surfaces following cell injury, this study evaluated renal excretion of CD59 in patients with idiopathic membranous glomerulonephritis (MGN; N = 21), diabetic nephropathy (DNP; N = 15) and in healthy control subjects (N = 13). CD59 in human urine was quantitated by a competitive solid-phase radioimmunoassay having approximately 13 kDa soluble urinary CD59 as a standard. Immunofluorescence microscopy demonstrated a decreased expression of CD59 in the glomeruli of MGN patients. Using a Triton X-114 phase separation method 91 to 97% of urinary CD59 was found to be in a soluble form without anchor-associated phospholipid. The mean (+/- SEM) level of urinary CD59 was 5.6 +/- 0.2 micrograms/ml in MGN patients, 3.7 +/- 0.4 micrograms/ml in healthy controls (P < 0.001) and 2.6 +/- 0.1 in DNP patients (P < 0.001). When related to urinary creatinine (UCr) the corresponding values were 11.9 +/- 5.6, 4.8 +/- 0.3 (P = 0.021) and 4.4 +/- 0.2 (P < 0.002), respectively. The amount of CD59 in urine correlated with the urinary excretion of soluble terminal complement complexes, SC5b-9 (r = 0.594, P < 0.006) in MGN patients. The excretion of CD59 also correlated with the excretion of the inflammatory mediator IL-1 beta (r = 0.671, P = 0.001) but not with TNF-alpha (r = 0.314, P = 0.178). No correlation of CD59 excretion was observed with duration of the disease level of proteinuria, serum albumin concentration or serum creatinine level. Based on these findings we speculate that the increased excretion of CD59 into urine in MGN patients is due to complement activation and inflammation induced shedding of CD59 from glomerular cells.
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PMID:Urinary excretion of protectin (CD59), complement SC5b-9 and cytokines in membranous glomerulonephritis. 754 24

These studies examined the expression of the podocyte slit diaphragm protein nephrin and its association with actin at the onset of proteinuria in passive Heymann nephritis (PHN), a rat model of human membranous nephropathy. Four days after immunization, 58% of PHN rats had mild proteinuria. At that time, most slit diaphragms were still visible on electron microscopy; however, in those locations where the deposits encroached on the filtration slits, the slit diaphragms were either displaced or absent. On day 7, the PHN rats were severely proteinuric, and most slit diaphragms were either absent, displaced, or replaced by occluding-type junctions. Immunofluorescence microscopy with antibodies to the external and cytoplasmic domains of nephrin showed a progressive loss of staining and a change in the distribution of nephrin from an interrupted linear pattern in normal controls to a more dispersed and clustered pattern in PHN. In contrast, the intensity of staining for ZO-1 and CD2-associated protein (CD2AP), two other proteins that are located on the cytoplasmic face of the slit diaphragm, was undiminished. Immunogold electron microscopy confirmed the progressive disappearance of nephrin from podocyte foot processes and retention of CD2AP. Glomeruli and glomerular cell membranes were extracted sequentially with Triton X-100, followed by DNase I or potassium iodide to depolymerize actin. Western blot analysis of the extracts showed a progressive decline of total nephrin on days 4 and 7 of PHN as well as a reduction in the actin-associated fraction. These findings show that nephrin partly dissociates from actin at the onset of podocyte injury in PHN. This is accompanied by a progressive loss of nephrin from the podocyte foot processes and prominent changes in the morphology of the slit diaphragms. These events may underlie the loss of podocyte barrier function in membranous nephropathy.
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PMID:Nephrin dissociates from actin, and its expression is reduced in early experimental membranous nephropathy. 1191 54

Glomerular visceral epithelial cells (podocytes) appear to play a central role in maintaining the selective filtration barrier of the renal glomerulus. While the immunoglobulin superfamily member Nephrin was proposed to act as a cell adhesion molecule at the podocyte intercellular junction necessary for maintaining glomerular perm selectivity, the Nephrin ligand has not been identified. The existence of a new subfamily of Nephrin-like molecules including Neph1 was recently described. Genetic deletion of Nephrin or Neph1 resulted in similar phenotypes of podocyte foot process effacement and proteinuria. The subcellular localization of Neph1 and the possibility that Nephrin and Neph1 interact was investigated. Polyclonal antiserum for Neph1 was raised and characterized. Neph1 migrated as a 90-kDa protein on SDS-PAGE under reducing conditions. Neph1 was identified in a glomerular and podocyte-specific distribution in adult rat kidney. Like Nephrin and Podocin, Neph1 was enriched in Triton X-100 detergent-resistant membrane fractions. Consistent with this observation, immunogold electron microscopy demonstrated that Neph1 localized exclusively to lateral margins of podocyte foot processes at the insertion of the slit diaphragm. Neph1 and Nephrin participate in a direct cis-interaction involving their cytoplasmic domains. In addition, interactions between the extracellular domain of Nephrin and itself and between the extracellular domain of Nephrin and that of Neph1 were detected. Neph1 did not interact via a homophilic interaction. These observations suggest that Nephrin and Neph1 form a hetero-oligomeric receptor complex in the plane of the membrane that might interact across the foot process intercellular junction through interactions between Nephrin with itself and Neph1.
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PMID:Nephrin and Neph1 co-localize at the podocyte foot process intercellular junction and form cis hetero-oligomers. 1264 66