The Experts below are selected from a list of 1239 Experts worldwide ranked by ideXlab platform
Mordecai M. Popovtzer - One of the best experts on this subject based on the ideXlab platform.
-
The ontogeny of the expression of K+ channel-like gene (CHIF) in the rat Kidney Papilla
Pediatric Nephrology, 1998Co-Authors: Yosef S. Haviv, Hanna Wald, H. Garty, Mordecai M. PopovtzerAbstract:Recently, an IsK-like potassium (K+) channel corticosteroid-induced gene (CHIF) was cloned. A high-K+ diet enhances, while a low-K+ diet decreases the expression of this gene. The major expression of CHIF in the adult rat Kidney is in the Papilla, where it is constitutive, in contrast to its inducibility by corticosteroids and a low-salt diet in the rat colon. In order to further understand the ontogeny of K+ clearance, we studied the presence of CHIF in the Kidney Papilla in different stages of rat development. Total RNA from rat Kidney Papillae of 1- to 3-day pre-labor unborn offspring, 2- to 3-day-old newborns, 10-day-old, 6-week-old, and 43-week-old rats underwent northern hybridization for CHIF and the α-subunit of the Na+-K+-ATPase mRNA. Minor expression of CHIF mRNA was found in fetal and newborn rat Papillae, while older rats showed an age-related increase in gene expression1.The expression of the α-sub unit of the Na+-K+-ATPase was not age related. We conclude that CHIF is present in the rat Kidney Papilla and the expression is related to age. The relative deficiency of CHIF in the newborn may be one of the factors responsible for the reduced K+ clearance in is period.
-
The ontogeny of the expression of K^+ channel-like gene (CHIF) in the rat Kidney Papilla
Pediatric Nephrology, 1998Co-Authors: Yosef S. Haviv, Hanna Wald, H. Garty, Mordecai M. PopovtzerAbstract:Recently, an IsK-like potassium (K^+) channel corticosteroid-induced gene ( CHIF ) was cloned. A high-K^+ diet enhances, while a low-K^+ diet decreases the expression of this gene. The major expression of CHIF in the adult rat Kidney is in the Papilla, where it is constitutive, in contrast to its inducibility by corticosteroids and a low-salt diet in the rat colon. In order to further understand the ontogeny of K^+ clearance, we studied the presence of CHIF in the Kidney Papilla in different stages of rat development. Total RNA from rat Kidney Papillae of 1- to 3-day pre-labor unborn offspring, 2- to 3-day-old newborns, 10-day-old, 6-week-old, and 43-week-old rats underwent northern hybridization for CHIF and the α-subunit of the Na^+-K^+-ATPase mRNA. Minor expression of CHIF mRNA was found in fetal and newborn rat Papillae, while older rats showed an age-related increase in gene expression^1.The expression of the α-sub unit of the Na^+-K^+-ATPase was not age related. We conclude that CHIF is present in the rat Kidney Papilla and the expression is related to age. The relative deficiency of CHIF in the newborn may be one of the factors responsible for the reduced K^+ clearance in is period.
H. Garty - One of the best experts on this subject based on the ideXlab platform.
-
The ontogeny of the expression of K+ channel-like gene (CHIF) in the rat Kidney Papilla
Pediatric Nephrology, 1998Co-Authors: Yosef S. Haviv, Hanna Wald, H. Garty, Mordecai M. PopovtzerAbstract:Recently, an IsK-like potassium (K+) channel corticosteroid-induced gene (CHIF) was cloned. A high-K+ diet enhances, while a low-K+ diet decreases the expression of this gene. The major expression of CHIF in the adult rat Kidney is in the Papilla, where it is constitutive, in contrast to its inducibility by corticosteroids and a low-salt diet in the rat colon. In order to further understand the ontogeny of K+ clearance, we studied the presence of CHIF in the Kidney Papilla in different stages of rat development. Total RNA from rat Kidney Papillae of 1- to 3-day pre-labor unborn offspring, 2- to 3-day-old newborns, 10-day-old, 6-week-old, and 43-week-old rats underwent northern hybridization for CHIF and the α-subunit of the Na+-K+-ATPase mRNA. Minor expression of CHIF mRNA was found in fetal and newborn rat Papillae, while older rats showed an age-related increase in gene expression1.The expression of the α-sub unit of the Na+-K+-ATPase was not age related. We conclude that CHIF is present in the rat Kidney Papilla and the expression is related to age. The relative deficiency of CHIF in the newborn may be one of the factors responsible for the reduced K+ clearance in is period.
-
The ontogeny of the expression of K^+ channel-like gene (CHIF) in the rat Kidney Papilla
Pediatric Nephrology, 1998Co-Authors: Yosef S. Haviv, Hanna Wald, H. Garty, Mordecai M. PopovtzerAbstract:Recently, an IsK-like potassium (K^+) channel corticosteroid-induced gene ( CHIF ) was cloned. A high-K^+ diet enhances, while a low-K^+ diet decreases the expression of this gene. The major expression of CHIF in the adult rat Kidney is in the Papilla, where it is constitutive, in contrast to its inducibility by corticosteroids and a low-salt diet in the rat colon. In order to further understand the ontogeny of K^+ clearance, we studied the presence of CHIF in the Kidney Papilla in different stages of rat development. Total RNA from rat Kidney Papillae of 1- to 3-day pre-labor unborn offspring, 2- to 3-day-old newborns, 10-day-old, 6-week-old, and 43-week-old rats underwent northern hybridization for CHIF and the α-subunit of the Na^+-K^+-ATPase mRNA. Minor expression of CHIF mRNA was found in fetal and newborn rat Papillae, while older rats showed an age-related increase in gene expression^1.The expression of the α-sub unit of the Na^+-K^+-ATPase was not age related. We conclude that CHIF is present in the rat Kidney Papilla and the expression is related to age. The relative deficiency of CHIF in the newborn may be one of the factors responsible for the reduced K^+ clearance in is period.
-
A corticosteroid-induced gene expressing an "IsK-like" K+ channel activity in Xenopus oocytes
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: Bernard Attali, Hedva Latter, Nurit Rachamim, H. GartyAbstract:Abstract Screening a rat colon cDNA library for aldosterone-induced genes resulted in the molecular cloning of a cDNA whose corresponding mRNA is strongly induced in the colon by dexamethasone, aldosterone, and a low NaCl diet. A similar mRNA was detected in Kidney Papilla but not in brain, heart, or skeletal muscle. Xenopus laevis oocytes injected with cRNA synthesized from this clone, designated CHIF (channel-inducing factor), express a K(+)-specific channel activity. The biophysical, pharmacological, and regulatory characteristics of this channel are very similar to those reported before for IsK (minK). These include: slow (tau > 20 s) activation by membrane depolarization with a threshold potential above -50 mV, blockade by clofilium, inhibition by phorbol ester, and activation by 8-bromoadenosine 3',5'-cyclic monophosphate and high cytoplasmic Ca2+. The primary structure of this clone, however, shows no homology to IsK. Instead, CHIF exhibits > 50% similarity to two other short bitopic membrane proteins, phospholemman and the gamma subunit of Na+K(+)-ATPase. The data are consistent with the possibility that CHIF is a member of a family of transmembrane regulators capable of activating endogenous oocyte transport proteins.
Dennis Brown - One of the best experts on this subject based on the ideXlab platform.
-
Heat shock protein 70 interacts with aquaporin-2 and regulates its trafficking.
Journal of Biological Chemistry, 2007Co-Authors: Tian-xiao Sun, Toshiyuki Matsuzaki, Jairam R. Eswara, Richard Bouley, Mary Mckee, Dennis BrownAbstract:The trafficking of aquaporin-2 (AQP2) involves multiple complex pathways, including regulated, cAMP-, and cGMP-mediated pathways, as well as a constitutive recycling pathway. Although several accessory proteins have been indirectly implicated in AQP2 recycling, the direct protein-protein interactions that regulate this process remain largely unknown. Using yeast two-hybrid screening of a human Kidney cDNA library, we have identified the 70-kDa heat shock proteins as AQP2-interacting proteins. Interaction was confirmed by mass spectrometry of proteins pulled down from rat Kidney Papilla extract using a GST-AQP2 C-terminal fusion protein (GST-A2C) as a bait, by co-immunoprecipitation (IP) assays, and by direct binding assays using purified hsc70 and the GST-A2C. The direct interaction of AQP2 with hsc70 is partially inhibited by ATP, and the Ser-256 residue in the AQP2 C terminus is important for this direct interaction. Vasopressin stimulation in cells enhances the interaction of hsc70 with AQP2 in IP assays, and vasopressin stimulation in vivo induces an increased co-localization of hsc70 and AQP2 on the apical membrane of principal cells in rat Kidney collecting ducts. Functional knockdown of hsc70 activity in AQP2 expressing cells results in membrane accumulation of AQP2 and reduced endocytosis of rhodamine-transferrin. Our data also show that AQP2 interacts with hsp70 in multiple in vitro binding assays. Finally, in addition to hsc70 and hsp70, AQP2 interacts with several other key components of the endocytotic machinery in co-IP assays, including clathrin, dynamin, and AP2. To summarize, we have identified the 70-kDa heat shock proteins as a AQP2 interactors and have shown for hsc70 that this interaction is involved in AQP2 trafficking.
-
A basolateral CHIP28/MIP26-related protein (BLIP) in Kidney principal cells and gastric parietal cells.
American Journal of Physiology-cell Physiology, 1994Co-Authors: Giovanna Valenti, Alan S. Verkman, J. M. Verbavatz, Ivan Sabolić, Dennis A. Ausiello, Dennis BrownAbstract:The water channel CHIP28 accounts for the high water permeability of proximal tubules and thin descending limbs of Henle; a homologous water channel, WCH-CD, in the apical membrane of collecting duct principal cells, may be the vasopressin-sensitive water channel. We show here that one antiserum, raised against CHIP28, immunostains the basolateral membrane of collecting duct principal cells, in addition to staining CHIP28 in other cells. This serum was named anti-basolateral integral protein (anti-BLIP) to distinguish it from other anti-CHIP28 antisera. By Western blotting, BLIP serum recognized both CHIP28 and MIP26, and it stained lens fibers, which contain MIP26 but not CHIP28. BLIP antiserum immunoprecipitated a 28-kDa band, a broad 35- to 50-kDa band, and an approximately 16-kDa band from Kidney Papilla. It also stained the basolateral membrane of gastric parietal cells, which were not stained with anti-CHIP28 or anti-MIP26 antibodies. BLIP antiserum immunoprecipitated a 28-kDa protein band from stomach; this protein was not precipitated by anti-CHIP28 antibodies. These results suggest that basolateral membranes of principal cells and parietal cells contain a protein(s) that shares common epitopes with CHIP28 and MIP26. Finally, BLIP but not CHIP28 antiserum stained mesothelial (but not epithelial) cells of toad urinary bladder, a further indication that the BLIP antiserum recognizes a protein distinct from CHIP28.
-
A 28 kDa sarcolemmal antigen in Kidney principal cell basolateral membranes: relationship to orthogonal arrays and MIP26.
Journal of cell science, 1994Co-Authors: J. M. Verbavatz, A S Verkman, Giovanna Valenti, Dennis A. Ausiello, A N Van Hoek, I Sabolic, M H Ellisman, Dennis BrownAbstract:Two recently cloned water channels, CHIP28 and WCH-CD, are homologous to MIP26, an integral membrane channel-forming protein found in lens fiber plasma membranes. CHIP28 is found in basolateral and apical plasma membranes of Kidney proximal tubules and thin descending limbs of Henle, whereas WCH-CD is apically located in collecting duct principal cells. So far, the putative water channel that may be responsible for the high constitutive permeability of principal cell basolateral membranes has not been identified. Interestingly, freeze-fracture electron microscopy has shown that characteristic orthogonal arrays of intramembrane particles (OAPs) are found on the basolateral plasma membranes of collecting duct principal cells, and that morphologically identical OAPs present in lens fiber cell plasma membranes contain the protein MIP26. Similar OAPs have also been detected on plasma membranes of other cell types including gastric parietal cells, astroglial cells and skeletal muscle fibers. By indirect immunofluorescence, western blotting and northern blotting, MIP26 was found only in lens fibers. In addition, functional studies on reconstituted and oocyte-expressed MIP26 excluded the possibility that MIP26 might be a basolateral water channel in the Kidney. However, a polyclonal antibody raised against skeletal muscle sarcolemmal vesicles, which are enriched in OAPs, produced an intense staining of principal cell basolateral plasma membranes in Kidney collecting duct and immunoprecipitated a 28 kDa protein from Kidney Papilla. The immunoprecipitated protein from Papilla was not recognized by anti-CHIP28 or anti-MIP26 antibodies, indicating that principal cell basolateral membranes contain a novel member of the CHIP/MIP family. Because this antibody also stained brain astrocyte end feet, which are enriched in OAPs, it is possible that the 28 kDa protein is related to these structures. We conclude that OAPs probably contain related but distinct proteins that may have different membrane channel functions in different cell types.
Alan S. Verkman - One of the best experts on this subject based on the ideXlab platform.
-
A basolateral CHIP28/MIP26-related protein (BLIP) in Kidney principal cells and gastric parietal cells.
American Journal of Physiology-cell Physiology, 1994Co-Authors: Giovanna Valenti, Alan S. Verkman, J. M. Verbavatz, Ivan Sabolić, Dennis A. Ausiello, Dennis BrownAbstract:The water channel CHIP28 accounts for the high water permeability of proximal tubules and thin descending limbs of Henle; a homologous water channel, WCH-CD, in the apical membrane of collecting duct principal cells, may be the vasopressin-sensitive water channel. We show here that one antiserum, raised against CHIP28, immunostains the basolateral membrane of collecting duct principal cells, in addition to staining CHIP28 in other cells. This serum was named anti-basolateral integral protein (anti-BLIP) to distinguish it from other anti-CHIP28 antisera. By Western blotting, BLIP serum recognized both CHIP28 and MIP26, and it stained lens fibers, which contain MIP26 but not CHIP28. BLIP antiserum immunoprecipitated a 28-kDa band, a broad 35- to 50-kDa band, and an approximately 16-kDa band from Kidney Papilla. It also stained the basolateral membrane of gastric parietal cells, which were not stained with anti-CHIP28 or anti-MIP26 antibodies. BLIP antiserum immunoprecipitated a 28-kDa protein band from stomach; this protein was not precipitated by anti-CHIP28 antibodies. These results suggest that basolateral membranes of principal cells and parietal cells contain a protein(s) that shares common epitopes with CHIP28 and MIP26. Finally, BLIP but not CHIP28 antiserum stained mesothelial (but not epithelial) cells of toad urinary bladder, a further indication that the BLIP antiserum recognizes a protein distinct from CHIP28.
-
Cloning, functional analysis and cell localization of a Kidney proximal tubule water transporter homologous to CHIP28.
Journal of Cell Biology, 1993Co-Authors: Rubin Zhang, H Hasegawa, William R. Skach, A. Van Hoek, Alan S. VerkmanAbstract:The localization and transporting properties of a Kidney protein homologous to human erythrocyte protein CHIP28 was evaluated. The cDNA encoding rat Kidney protein CHIP28k was isolated from a rat renal cortex cDNA library. A 2.8-kb cDNA was identified which contained an 807 bp open reading frame encoding a 28.8 kD protein with 94% amino acid identity to CHIP28. in vitro translation of CHIP28k cDNA in rabbit reticulocyte lysate generated a 28-kD protein; addition of ER-derived microsomes gave a 32-kD transmembrane glycoprotein. Translation of truncated RNA demonstrated glycosylation of residue Asn42 which is predicted to lie between the first and second transmembrane domains. Expression of in vitro transcribed mRNA encoding CHIP28k in Xenopus oocytes increased oocyte osmotic water permeability (Pf) from (4 +/- 1) x 10(-4) to (33 +/- 4) x 10(-4) cm/s at 10 degrees C; the increase in oocyte Pf was weakly temperature dependent and inhibited by HgCl2. Two-electrode voltage clamp measurements indicated that CHIP28k was not permeable to ions. Oocyte Pf also increased with expression of total mRNA from Kidney cortex and Papilla; the increase in Pf with mRNA from cortex, but not Kidney Papilla, was blocked by coinjection with excess antisense CHIP28k cRNA. In situ hybridization of a 150 base cRNA antisense probe to tissue sections from rat Kidney showed selective CHIP28k localization to epithelial cells in proximal tubule and thin descending limb of Henle. Pf in purified apical membrane vesicles from rat and human proximal tubule, and in proteoliposomes reconstituted with purified protein, was very high and inhibited by HgCl2; stripping of apical vesicles with N-lauroylsarcosine enriched a 28-kD protein by 25-fold and yielded a vesicle population with high water, but low urea and proton permeabilities. CHIP28k identity was confirmed by NH2-terminus sequence analysis. These results indicate that CHIP28k is a major and highly selective water transporting protein in the Kidney proximal tubule and thin descending limb of Henle, but not collecting duct.
-
Expression of mRNA coding for Kidney and red cell water channels in Xenopus oocytes.
Journal of Biological Chemistry, 1990Co-Authors: R B Zhang, K A Logee, Alan S. VerkmanAbstract:Abstract The existence and identity of protein water transporters in biological membranes has been uncertain. Osmotic water permeability (Pf) was measured in defolliculated Xenopus oocytes microinjected with water or mRNA from Kidney cortex, Kidney Papilla, reticulocyte, brain, and muscle. Pf was measured by quantitative image analysis from the time course of oocyte swelling in response to an osmotic gradient. When assayed at 10 degrees C, Pf in water-injected oocytes increased from (3.6 +/- 0.9) x 10(-4) cm/s (S.D., n = 16) to 74 x 10(-4) cm/s with addition of amphotericin B, showing absence of unstirred layers. At 48-72 h after injection of 50 ng of unfractionated mRNA, Pf (in cm/s x 10(-4] was: 4.0 +/- 1.5 (rabbit brain, n = 15), 4.2 +/- 1.8 (rabbit muscle, n = 10), 18.4 +/- 6.3 (rabbit reticulocyte, n = 20), 16.1 +/- 5.6 (rat renal Papilla, n = 24), 12.9 +/- 6.3 (rat renal cortex, n = 20), 14.4 +/- 6.1 (rabbit renal Papilla, n = 15), and 11.8 +/- 3.4 (rabbit renal cortex, n = 8). In oocytes injected with mRNA from rat renal Papilla, Pf was inhibited reversibly by 0.3 mM HgCl2 (4.1 +/- 1.6, n = 10); expressed water channels from Kidney and red cell had activation energies of less than 4 kcal/mol. These results show functional oocyte expression of water channels from red cell, Kidney proximal tubule (cortex), and the vasopressin-sensitive Kidney collecting tubule (Papilla), indicating that water channels are proteins, and providing an approach for the expression cloning of water channels.
Yosef S. Haviv - One of the best experts on this subject based on the ideXlab platform.
-
The ontogeny of the expression of K+ channel-like gene (CHIF) in the rat Kidney Papilla
Pediatric Nephrology, 1998Co-Authors: Yosef S. Haviv, Hanna Wald, H. Garty, Mordecai M. PopovtzerAbstract:Recently, an IsK-like potassium (K+) channel corticosteroid-induced gene (CHIF) was cloned. A high-K+ diet enhances, while a low-K+ diet decreases the expression of this gene. The major expression of CHIF in the adult rat Kidney is in the Papilla, where it is constitutive, in contrast to its inducibility by corticosteroids and a low-salt diet in the rat colon. In order to further understand the ontogeny of K+ clearance, we studied the presence of CHIF in the Kidney Papilla in different stages of rat development. Total RNA from rat Kidney Papillae of 1- to 3-day pre-labor unborn offspring, 2- to 3-day-old newborns, 10-day-old, 6-week-old, and 43-week-old rats underwent northern hybridization for CHIF and the α-subunit of the Na+-K+-ATPase mRNA. Minor expression of CHIF mRNA was found in fetal and newborn rat Papillae, while older rats showed an age-related increase in gene expression1.The expression of the α-sub unit of the Na+-K+-ATPase was not age related. We conclude that CHIF is present in the rat Kidney Papilla and the expression is related to age. The relative deficiency of CHIF in the newborn may be one of the factors responsible for the reduced K+ clearance in is period.
-
The ontogeny of the expression of K^+ channel-like gene (CHIF) in the rat Kidney Papilla
Pediatric Nephrology, 1998Co-Authors: Yosef S. Haviv, Hanna Wald, H. Garty, Mordecai M. PopovtzerAbstract:Recently, an IsK-like potassium (K^+) channel corticosteroid-induced gene ( CHIF ) was cloned. A high-K^+ diet enhances, while a low-K^+ diet decreases the expression of this gene. The major expression of CHIF in the adult rat Kidney is in the Papilla, where it is constitutive, in contrast to its inducibility by corticosteroids and a low-salt diet in the rat colon. In order to further understand the ontogeny of K^+ clearance, we studied the presence of CHIF in the Kidney Papilla in different stages of rat development. Total RNA from rat Kidney Papillae of 1- to 3-day pre-labor unborn offspring, 2- to 3-day-old newborns, 10-day-old, 6-week-old, and 43-week-old rats underwent northern hybridization for CHIF and the α-subunit of the Na^+-K^+-ATPase mRNA. Minor expression of CHIF mRNA was found in fetal and newborn rat Papillae, while older rats showed an age-related increase in gene expression^1.The expression of the α-sub unit of the Na^+-K^+-ATPase was not age related. We conclude that CHIF is present in the rat Kidney Papilla and the expression is related to age. The relative deficiency of CHIF in the newborn may be one of the factors responsible for the reduced K^+ clearance in is period.
