Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We selectively focus on two growth factors, epidermal growth factor (EGF) and insulin-like growth factor (IGF), and discuss their roles on regulation of renal function and associated diseases conditions, as well. EGF, 6 kD polypeptide, is derived by proteolysis from a large precursor (prepro EGF, 133 kD). Prepro EGF is a membrane-anchored protein and its mRNA is predominantly localized to distal tubules of mouse and rat kidneys. We immunohistochemically demonstrated the glomerular distribution of EGF and EGF-receptor in normal and nephritic human kidneys. The physiologic roles of EGF produced in the kidney are various; it is mitogenic for tubular epithelial cell, inhibits gluconeogenesis and salt and water reabsorption in the tubules, and effects on glomerular hemodynamics. Alteration of renal EGF expression is suggested in renal ischemic injury, renal hypertrophy and cystic renal disease. IGF-I, somatomedin-C, is produced in collecting duct, and glomerular cells, and exerts a variety of actions on kidney. IGF-I stimulates gluconeogenesis in renal tubules, and is mitogenic for mesangial cells. The administration of this growth factor increases glomerular filtration rate. Enhanced expression of renal IGF-I was observed in the uninephrectomized animals.
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PMID:[Growth factors: a regulator of renal function]. 149 47

We describe a 20-kDa phosphorylated polypeptide, which is secreted constitutively at the apical surface of the kidney-derived Madin-Darby canine kidney cell line. Using polyclonal antibodies raised against this protein, we show that it is generated from a 60-kDa O-glycosylated, sulfated, and phosphorylated precursor protein by an intracellular proteolytic maturation step, which is pH-sensitive. Amino acid sequence analysis of the 20-kDa secreted polypeptide demonstrated that it displays 70% identity with the carboxyl-terminal amino acids of human osteopontin. The amino-terminal amino acid of the 20-kDa polypeptide corresponds to amino acid 213 of human osteopontin. Thrombin has been shown to cleave rat osteopontin in vivo and in vitro at amino acid 153, yielding two fragments of 28 and 26 kDa. A similar cleavage product can be detected by thrombin treatment of the 60-kDa precursor, suggesting that the precursor is identical or closely related to osteopontin. In the rat nephron, the protein has been localized along the luminal surfaces of the proximal and distal tubule and the collecting duct cells. These results show that in the kidney-derived cell line Madin-Darby canine kidney osteopontin or a closely related protein is proteolytically processed to a 20-kDa polypeptide, raising the possibility that diverse functions of osteopontin in various tissues might be attributed to specific processing to distinct polypeptides.
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PMID:Biosynthesis and secretion of an osteopontin-related 20-kDa polypeptide in the Madin-Darby canine kidney cell line. 199 15

cDNA clones coding for the gp 80 heterodimeric glycoprotein complex secreted constitutively at the apical surface of Madin-Darby canine kidney (MDCK) cells have been isolated from MDCK cDNA libraries in lambda gt11 and lambda gt10. The cloned sequences encode a polypeptide chain of 445 amino acids. The deduced amino acid sequence of the gp 80 protein reveals 80% homology to rat SGP-2, a major secretory protein of the testes epithelium and 83% homology to SP-40,40, a human complement-associated protein. SGP-2 and SP-40,40 have been proposed to be serum and seminal forms of the same protein. The sequence homology as well as the results of Southern and Northern blot analyses and immunological studies suggest that gp 80 is the canine homolog of the rat SGP-2 and the human SP-40,40. The protein is expressed in the embryonic kidney already early during organogenesis. In the adult kidney the protein has been localized along the luminal surfaces of the proximal and distal tubule and the collecting duct cells.
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PMID:Molecular cloning of gp 80, a glycoprotein complex secreted by kidney cells in vitro and in vivo. A link to the reproductive system and to the complement cascade. 203 78

Epidermal growth factor (EGF) is a 53-amino acid polypeptide that is known to produce a number of biologic effects both in vitro and in vivo. High concentrations of EGF are found in urine, and high concentrations of prepro-EGF mRNA have been detected in kidney, localized to thick ascending limb of Henle (TALH) and distal convoluted tubule. Specific high-affinity EGF receptors have been demonstrated in mesangial cells, proximal tubule, and cortical and inner medullary collecting duct, as well as in medullary interstitial cells. In the proximal tubule, EGF binding and EGF receptor-associated tyrosine kinase activity are localized to basolateral membrane, and functional responses in collecting duct are observed only with basolateral administration of EGF. A number of renal responses to administration of EGF have recently been described, including modulation of glomerular hemodynamics, renal metabolism, tubular transport functions, and eicosanoid synthesis. In addition, EGF has been shown to be a potent mitogen in vitro for a variety of cell types in the kidney and may be an important mediator of renal repair following injury.
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PMID:Potential physiologic roles for epidermal growth factor in the kidney. 204 35

At least two configurations of intercalated cells, type A and type B, are present in the cortical collecting duct. Intercalated cells are rich in carbonic anhydrase. However, it is not known whether there are differences in the level and subcellular distribution of this enzyme between type A and type B intercalated cells. The purpose of this study was to determine the relative content and intracellular distribution of carbonic anhydrase II in the various subpopulations of intercalated cells in the rat collecting duct. A rabbit polyclonal antibody directed against mouse erythrocyte carbonic anhydrase II was employed to localize carbonic anhydrase, II by light and electron microscopy by an indirect immunoperoxidase method. A Western immunoblot analysis of homogenates of rat kidney cortex and medulla with the carbonic anhydrase II antibody revealed a single polypeptide band at 29 kDa corresponding to the molecular size of carbonic anhydrase II. By both light and electron microscopy, carbonic anhydrase II immunoreactivity was present in all intercalated cells but the intensity of staining was much greater in type A than in type B cells. In addition, immunostaining in type A cells was especially pronounced in the apical cytoplasm and apical microprojections whereas in type B cells, immunostaining was more diffuse throughout the cytoplasm. A third configuration of intercalated cell with diffuse immunostaining for carbonic anhydrase II was occasionally observed in the connecting segment. Very weak immunostaining was present in principal cells, whereas connecting tubule cells and inner medullary collecting duct cells were negative for carbonic anhydrase II.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ultrastructural localization of carbonic anhydrase II in subpopulations of intercalated cells of the rat kidney. 212 9

Growth hormone (GH) exerts a variety of metabolic and anabolic effects on skeletal and soft tissues including kidney. Some of these actions are mediated directly, whereas others result from GH-dependent synthesis and release of polypeptide growth factors designated insulin-like growth factors (IGFs). Receptors for GH are present in proximal tubule and GH directly stimulates gluconeogenesis at this site. IGF receptors are found in glomerulus and proximal tubule. Mechanisms for signal transduction by GH and IGFs have been characterized using proximal tubular basolateral membranes. IGFs regulate metabolic and transport processes in cultured glomerular mesangial cells and in isolated proximal tubular cells. IGF I is synthesized in cultured mesangial cells and is produced in a GH-dependent manner in cortical and medullary collecting duct. Evidence has accumulated that IGF I of renal origin functions as a paracrine growth factor in the settings of GH-induced hypertrophy and compensatory hypertrophy of the kidney, and in the setting of proximal tubular regeneration following ischemic injury. IGFs are embryonal mitogens and IGF II may act as a transforming agent for Wilms' tumor. Further characterization of the GH-IGF axis in kidney will provide additional insights into the roles of these peptides as regulators of renal function, growth, and development.
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PMID:The growth hormone-insulin-like growth factor axis in kidney. 267 42

Intrarenal arterial infusion of a synthetic alpha-human atrial natriuretic polypeptide (alpha-hANP) in a dose of 5.0 micrograms/min to anesthetized dogs led to a significant increase in urine flow and urinary excretion of electrolytes. Tubular sites of action of alpha-hANP were determined by using free water clearance techniques and in stop-flow experiments. During water diuresis, free water clearance did not increase in proportion to the increase in urine flow rate. Intrarenal administration of the peptide to dehydrated animals resulted in no change in solute-free water reabsorption, notwithstanding a significant increase in osmolar clearance. These data suggest that the peptide acts on the diluting segment of the ascending limb of Henle and also at the distal nephrons, findings which support data obtained in stop-flow experiments. Infusion of the peptide lowered inulin concentration and elevated sodium concentration in the stop-flow urine from the distal tubules and collecting duct. It is tentatively concluded that alpha-hANP produces potent diuretic and natriuretic responses by suppressing water and sodium transport in the distal portion of the nephron.
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PMID:Possible tubular site of action in anesthetized dogs of a synthetic alpha-human atrial natriuretic polypeptide. 294 79

In order to identify the molecular size of receptors for alpha-rat atrial natriuretic polypeptide (alpha-rANP), we utilized the direct UV irradiation method for photoaffinity labeling with the biologically active [125I] alpha-rANP. In the preparation of isolated glomerulus and the inner medullary collecting duct (IMCT)-rich fraction, the autoradiograms of the electrophoresed sodium dodecyl sulfate (SDS)-polyacrylamide gels showed a single radioactive band which is displaceable with unlabeled alpha-rANP. The dose-dependent displacement fit very well with a binding-inhibition curve representing the binding affinity of 6.5 X 10(-10) M. The molecular size of the ligand-receptor complex was about 65,000 daltons for both glomerulus and IMCT-rich fraction. In contrast, in homogenate of the aorta and adrenal gland, the ligand-receptor complex was 140,000 daltons.
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PMID:Difference in molecular size of receptors for alpha-rat atrial natriuretic polypeptide among the kidney, aorta, and adrenal gland as identified by direct UV-photoaffinity labeling. 301 Sep 63

Epidermal growth factor (EGF) is a potent polypeptide mitogen with various receptor-mediated growth effects on cells from the skin, breast, and gastrointestinal tract. Recent studies indicate that EGF is produced in the kidney and is excreted in the urine, but the biological significance of renal EGF is uncertain. We demonstrate in vitro mitogenicity of EGF for LLC-PK1 cells, a tubular epithelial cell line derived from pig kidney cortex. Furthermore, when subconfluent monolayers of LLC-PK1 cells are exposed to EGF for 24 h, sodium-dependent phosphate transport is stimulated (209-410% of control). These cells possess EGF-specific high-affinity binding sites at their surface (Kd 300-700 pM) but cannot synthesize the growth factor. EGF binding sites are not a peculiarity of the LLC-PK1 cell line, since similar sites are present on MDCK cells (derived from dog kidney distal tubule or collecting duct), primary cultures of mouse proximal tubular cells, and freshly prepared membrane fractions from mouse kidney. Cortical basolateral membranes are highly enriched in EGF binding sites, whereas EGF binding by brush-border membrane fractions is minimal and is compatible with contamination.
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PMID:Renal tubular cells are potential targets for epidermal growth factor. 326 62

Poly- and monoclonal antibodies have been prepared against the cytoplasmic domain (43 kDa) and the 17-, 20-, and 35-kDa fragments of the membrane-spanning domain of the human erythrocyte anion exchanger, band 3. The antibodies were used to localize and further characterize analogues of band 3 in the human kidney. We report here that the basolateral membrane of intercalated cells of the connecting tubules and collecting ducts contains an analogue of band 3 that appears to be highly homologous to the erythrocyte anion exchanger. This band 3-like protein is probably important for reabsorption of bicarbonate in the collecting duct system and thus for acidification of the forming urine. The band 3-like protein of the intercalated cells contain immunoreactive sites of both the cytoplasmic domain and the three major fragments of the membrane-spanning domain of erythrocyte band 3. Although no immunological differences were detected between the membrane-spanning domains of band 3 in erythrocytes and intercalated cells, there are at least three sites along the cytoplasmic domain of kidney band 3 that differ from erythrocyte band 3 in either amino acid composition or posttranslational modifications. The main kidney analogue of band 3 that contains epitopes of the cytoplasmic domain as well as the 17- and 35-kDa membrane-spanning domain of erythroid band 3 is a polypeptide with an apparent molecular mass of 100-110 kDa. Further immunoreactive polypeptides at approximately 180, approximately 140, approximately 38, approximately 25-30 kDa that were detected at lower stringency and higher sensitivity of the immunoblotting procedure may be members of a multigene family that encodes a series of related proteins.
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PMID:Immunochemical characterization of a band 3-like anion exchanger in collecting duct of human kidney. 361 86


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