Role of PKC isozyme III (γ) in water transport in amphibian urinary bladder

1992 ◽  
Vol 50 (1) ◽  
pp. 796-797
Author(s):  
A.J Mia ◽  
L.X. Oakford ◽  
P.D. Thompson ◽  
Z.H. Ning ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Phorbol Esters ◽  
Apical Membrane ◽  
Protein A ◽  
Water Channels ◽  
Renal Epithelia ◽  
Amphibian Urinary Bladder ◽  
Pkc Isozymes

Vasopressin stimulated water flow across renal epithelia is thought to occur through a V2 receptor coupled to adenylcyclase. The increase in water flow occurs as a result of a fusion of water channels with the apical membrane and is indicative of an increase in membrane capacitance following hormone addition.What controls the cycling of water channels and their insertion into the membrane is uncertain. Our laboratory has demonstrated that renal epithelia as well as amphibian urinary bladder membranes, contain a vasopressin V1 receptor which upon activation results in the breakdown of phosphoinositide and the formation of inositol triphosphate and diacylglycerol, the latter an activator of protein kinase C (PKC). The initiation of transepithelial water flow also appears to involve V1 receptors and possibly activation of PKC. To test this hypothesis, we have been using activators of PKC, such as phorbol esters and mezerein, as pharmacological tools to determine if PKC activation results in similar physiological responses as the hormone. Several PKC isozymes, upon activation, are known to be translocated to the apical membrane as visualized by FITC immunofluorescence. Previously, we reported co-localization of PKC subtypes I (γ) and II (β) in toad urinary bladders using monoclonal antibodies and protein A-gold probes. This report includes the localization of PKC subtype III (α) and its distribution pattern using immunogold labeling.

Role of PKC isozymes in water transport in toad urinary bladder

1991 ◽  
Vol 49 ◽  
pp. 302-303
Author(s):  
A.J. Mia ◽  
L.X. Oakford ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Apical Membrane ◽  
Membrane Surface ◽  
Protein A ◽  
Cell Types ◽  
Leukemic Cells ◽  
Toad Urinary Bladder ◽  
Pkc Isozymes ◽  
Antibody Labeling

Protein kinase C (PKC) isozymes, when activated, are translocated to particulate membrane fractions for transport to the apical membrane surface in a variety of cell types. Evidence of PKC translocation was demonstrated in human megakaryoblastic leukemic cells, and in cardiac myocytes and fibroblasts, using FTTC immunofluorescent antibody labeling techniques. Recently, we reported immunogold localizations of PKC subtypes I and II in toad urinary bladder epithelia, following 60 min stimulation with Mezerein (MZ), a PKC activator, or antidiuretic hormone (ADH). Localization of isozyme subtypes I and n was carried out in separate grids using specific monoclonal antibodies with subsequent labeling with 20nm protein A-gold probes. Each PKC subtype was found to be distributed singularly and in discrete isolated patches in the cytosol as well as in the apical membrane domains. To determine if the PKC isozymes co-localized within the cell, a double immunogold labeling technique using single grids was utilized.

ADH-induced water permeability and particle aggregates: alteration by a synthetic estrogen

1991 ◽  
Vol 261 (1) ◽  
pp. F144-F152 ◽  
Author(s):  
G. Calamita ◽  
Y. Le Guevel ◽  
J. Bourguet
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Water Permeability ◽  
Glucose Transporter ◽  
Apical Membrane ◽  
Selective Inhibition ◽  
Synthetic Estrogen ◽  
Permeability Changes ◽  
Particle Aggregates ◽  
Amphibian Urinary Bladder

In the amphibian urinary bladder, the increase in water permeability induced by antidiuretic hormone (ADH) is accompanied by the appearance of apical intramembrane particle (IMP) aggregates that are believed to contain specific channels for water. In a previous work, we have shown that 3,3'-diallyldiethylstilbestrol (DADES), a synthetic estrogen which is a blocker of the glucose transporter, also inhibits the hydrosmotic response to ADH in the bladder. Our aim in the present study was to analyze the alterations of the membrane fine structure further and to correlate them with the water permeability changes. The results point to a selective inhibition of the ADH-induced net water flow, probably due to an interference with one of the last steps of the response to the hormone. This inhibition is associated with an increase in the density of the apical IMP aggregates, which are thus probably not operational. The resting net water flow is not inhibited and, surprisingly, typical IMP aggregates are frequently observed in the apical membrane after DADES treatment. The compound also induces the appearance of unusual loose IMP clusters that can only be seen on the apical membrane of the granular cells and that share several ultrastructural similarities with the ADH-induced aggregates. These results suggest that 1) apical DADES treatment stimulates the insertion of IMP aggregates in the apical membrane of the urinary bladder and 2) DADES inhibits the ADH-induced water flow by interfering with the aggregates and thus probably by blocking the specific water channels.

Alterations in surface substructure and degranulation of subapical cytoplasmic granules by mezereinu (MZ) in toad urinary bladder epithelia

1989 ◽  
Vol 47 ◽  
pp. 916-917
Author(s):  
A. J. Mia ◽  
L. X. Oakfoid ◽  
T. Yorio
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Urinary Bladder ◽  
Water Flow ◽  
Apical Membrane ◽  
Water Channels ◽  
Phosphoinositide Metabolism ◽  
Apical Surface ◽  
Ultrastructural Studies ◽  
Kinase C

The increase in transepithelial water flow induced by antidiuretic hormone (ADH) occurs through the ADH V2 receptor, and includes the stimulation of adenylcyclase, an increase in cAMP synthesis and the activation of protein kinase A. These biochemical events in amphibian urinary bladder tissues are reported to be accompanied by apical membrane transformations including the induction of numerous microvilli, and an increase in apical surface area as a result of incorporation of water channels. Amphibian epithelia also contain an ADH V1 receptor coupled to phosphoinositide metabolism and inositol phosphate release. Recently, it was demonstrated that mezerein (MZ), a non-phorbol activator of protein kinase C (PKC)increased transepithelial water flow when added to mucosal surface. The magnitude of water transport was less and occurred over a longer period of time than compared to ADH-stimulated tissues (7,and also Table 1). However, there is little or no information available on ultrastructural studies linking the events due to the ADH V1 receptor and osmotic water flow. Presently, we report on morphological and cytological observations which suggests that the ADH V1 receptor cascade may play a role in the insertion of water channels into the apical membrane possibly through the activation of PKC. The present study utilizes mezerein (MZ), a non-phorbol activator of protein kinase C (PKC) to examine the effect of MZ on epithelial cytomorphology.

Effect of verapamil on cytoplasmic distribution of granules and microfilaments in amphibian urinary bladder

1988 ◽  
Vol 46 ◽  
pp. 324-325
Author(s):  
A.J. Mia ◽  
L.X. Oakford ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Morphological Changes ◽  
Granular Cell ◽  
Cytosolic Calcium ◽  
Calcium Storage ◽  
Amphibian Urinary Bladder ◽  
Vesicular Membrane ◽  
High Concentrations ◽  
Cytoskeletal System

The amphibian urinary bladder has been used as a ‘model’ system for studies of the mechanism of action of antidiuretic hormone (ADH) in stimulating transepithelial water flow. The increase in water permeability is accompanied by morphological changes that include the stimulation of apical microvilli, mobilization of microtubules and microfilaments and vesicular membrane fusion events . It has been shown that alterations in the cytosolic calcium concentrations can inhibit ADH transmembrane water flow and induce alterations in the epithelial cell cytomorphology, including the cytoskeletal system . Recently, the subapical granules of the granular cell in the amphibian urinary bladder have been shown to contain high concentrations of calcium, and it was suggested that these cytoplasmic constituents may act as calcium storage sites for intracellular calcium homeostasis. The present study utilizes the calcium antagonist, verapamil, to examine the effect of calcium deprivation on the cytomorphological features of epithelial cells from amphibian urinary bladder, with particular emphasis on subapical granule and microfilament distribution.

Polyclonal antibodies in study of ADH-induced water channels in frog urinary bladder

1991 ◽  
Vol 261 (3) ◽  
pp. F437-F442
Author(s):  
G. Valenti ◽  
G. Calamita ◽  
M. Svelto
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Apical Membrane ◽  
Polyclonal Antibodies ◽  
Immune Serum ◽  
Frog Urinary Bladder ◽  
Hormonal Stimulation ◽  
Osmotic Water ◽  
Triton X ◽  
Osmotic Water Flow

It is now generally accepted that changes in water permeability in anti-diuretic hormone (ADH)-responsive target epithelial cells result from the insertion in the plasma apical membrane of new components that contain channels for water. The specificity of these channels suggests that they are formed by intrinsic proteins having access to both facies and spanning the whole membrane. We have previously shown that Triton X-100 apical extracts from ADH-stimulated frog urinary bladder contain some proteins inserted under hormonal stimulation. In the present study we have developed polyclonal antibodies using Triton X-100 extract as an immunogen. After considering the inhibitory effect exerted by the whole immune serum on the osmotic water flow, we used different adsorption steps to select, from the immune serum, antibodies to apical membrane proteins inserted in response to the hormone. Immunoblot analysis of these selected antibodies shows that they recognize seven to eight proteins, of which 55-, 35-, 26-, and 17-kDa proteins are always present. Antibodies to these four proteins, affinity purified on nitrocellulose sheets, inhibited ADH-induced osmotic water flow. Altogether these results strongly suggest that proteins of 55, 35, 26, and 17 kDa (or at least one of them) are likely to be involved in the mechanism of water transport.

Acidification of vasopressin-induced endosomes in toad urinary bladder

1994 ◽  
Vol 267 (1) ◽  
pp. F106-F113
Author(s):  
F. Emma ◽  
H. W. Harris ◽  
K. Strange
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Apical Membrane ◽  
Fluid Phase ◽  
Endocytic Pathway ◽  
Toad Urinary Bladder ◽  
Acidic Ph ◽  
Terminal Event ◽  
Ultimate Fate

It is well established that water channels (WC) are removed from the apical membrane of vasopressin-sensitive epithelia by endocytosis. The processing and the ultimate fate of endocytosed WC is, however, incompletely understood. In many cells, endosome acidification plays an important role in the processing and sorting of endocytosed proteins. Endosome acidification in the toad urinary bladder was therefore examined in vivo by fluorescence ratio video microscopy after induction of endocytosis by vasopressin removal and transepithelial water flow in the presence of the pH-sensitive fluid phase marker 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein-dextran. Fifteen minutes after induction of endocytosis, the majority of endosomes had a neutral or slightly acidic pH. The number of acidic endosomes increased progressively with time. Two hours after endocytosis began, 98% of the endosomes had a pH < 6.0. Bafilomycin completely blocked endosome acidification, indicating that H+ transport is mediated by a vacuolar H(+)-adenosinetriphosphatase. Bafilomycin had no effect on transepithelial water flow in bladders repetitively stimulated by vasopressin. These findings, as well as the work of other investigators, suggest that if WC recycling occurs, it is not dependent on acidification of the endosomal compartment. Acidification of vasopressin-induced endosomes most likely represents a terminal event in the endocytic pathway.

Modulation of antidiuretic hormone-dependent capacitance and water flow in toad urinary bladder

1984 ◽  
Vol 246 (4) ◽  
pp. F501-F508
Author(s):  
L. G. Palmer ◽  
N. Speez
Keyword(s):  
Urinary Bladder ◽  
Antidiuretic Hormone ◽  
Water Flow ◽  
Water Permeability ◽  
Apical Membrane ◽  
Toad Urinary Bladder ◽  
Osmotic Gradient ◽  
Apical Surface ◽  
Membrane Area ◽  
Close Relationship

To test the hypothesis that antidiuretic hormone- (ADH) dependent water permeability is associated with changes in apical membrane area, hormone-dependent water flow and capacitance changes were measured in the toad urinary bladder under a number of different conditions. Dose-response relationships for water flow (Jv) and capacitance increases (delta C) were similar from 1 to 20 mU/ml ADH. At higher concentrations, Jv reached a plateau, while delta C decreased. The decrease in delta C was prevented by elimination of the osmotic gradient across the tissue. Serosal hydrazine (10 mM) increased Jv sevenfold and delta C threefold in the presence of 1 mU/ml ADH. Mucosal NH4Cl, at constant mucosal pH, increased Jv by 50-100%, but did not significantly change delta C. In the absence of an osmotic gradient, mucosal NH+4 increased delta C by 50%. NH4Cl had no effect on hydroosmotic response to 8-bromo-adenosine 3',5'-cyclic monophosphate (cAMP). Mucosal CO2 (9%) decreased Jv by greater than 90%, and delta C by 60% with 20 mU/ml ADH. Mucosal CO2 also inhibited the hydroosmotic response to 8-bromo-cAMP. Removal of serosal Na diminished cAMP-dependent Jv and delta C. The results confirmed the close relationship between ADH-dependent water permeability and membrane capacitance. They indicate, however, that under some circumstances membrane may be retrieved from the apical surface without affecting water permeability.

Protein kinase C regulates endocytosis and recycling of E-cadherin

2002 ◽  
Vol 283 (2) ◽  
pp. C489-C499 ◽  
Author(s):  
Tam Luan Le ◽  
Shannon R. Joseph ◽  
Alpha S. Yap ◽  
Jennifer L. Stow
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Esters ◽  
Recycling Endosomes ◽  
Kinase C ◽  
Pkc Isozymes ◽  
Pkc Activation ◽  
Darby Canine Kidney ◽  
E Cadherin

E-cadherin is a major component of adherens junctions in epithelial cells. We showed previously that a pool of cell surface E-cadherin is constitutively internalized and recycled back to the surface. In the present study, we investigated the potential role of protein kinase C (PKC) in regulating the trafficking of surface E-cadherin in Madin-Darby canine kidney cells. Using surface biotinylation and immunofluorescence, we found that treatment of cells with phorbol esters increased the rate of endocytosis of E-cadherin, resulting in accumulation of E-cadherin in apically localized early or recycling endosomes. The recycling of E-cadherin back to the surface was also decreased in the presence of phorbol esters. Phorbol ester-induced endocytosis of E-cadherin was blocked by specific inhibitors, implicating novel PKC isozymes, such as PKC-ε in this pathway. PKC activation led to changes in the actin cytoskeleton facilitating E-cadherin endocytosis. Depolymerization of actin increased endocytosis of E-cadherin, whereas the PKC-induced uptake of E-cadherin was blocked by the actin stabilizer jasplakinolide. Our findings show that PKC regulates vital steps of E-cadherin trafficking, its endocytosis, and its recycling.

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