Hypoxia induces basolateral membrane remodeling in T84 intestinal epithelia: Role of PKCe and PLCГ

2000 ◽  
Vol 118 (4) ◽  
pp. A613
Author(s):  
Edward C. Mun ◽  
Jaekyung C. Song ◽  
Celina M. Hanson ◽  
Jeffrey B. Matthews
Keyword(s):  
Basolateral Membrane ◽  
Membrane Remodeling ◽  
Intestinal Epithelia

Opposing effects of PKCα and PKCε on basolateral membrane dynamics in intestinal epithelia

2002 ◽  
Vol 283 (5) ◽  
pp. C1548-C1556 ◽  
Author(s):  
Jaekyung Cecilia Song ◽  
Patangi K. Rangachari ◽  
Jeffrey B. Matthews
Keyword(s):  
Time Course ◽  
Basolateral Membrane ◽  
Membrane Dynamics ◽  
T84 Cells ◽  
Intestinal Epithelia ◽  
Early Activation ◽  
Pkc Isoforms ◽  
Opposing Effects ◽  
Stimulation Of

PKC is a critical effector of plasma membrane dynamics, yet the mechanism and isoform-specific role of PKC are poorly understood. We recently showed that the phorbol ester PMA (100 nM) induces prompt activation of the novel isoform PKCε followed by late activation of the conventional isoform PKCα in T84 intestinal epithelia. PMA also elicited biphasic effects on endocytosis, characterized by an initial stimulatory phase followed by an inhibitory phase. Activation of PKCε was shown to be responsible for stimulation of basolateral endocytosis, but the role of PKCα was not defined. Here, we used detailed time-course analysis as well as selective activators and inhibitors of PKC isoforms to infer the action of PKCα on basolateral endocytosis. Inhibition of PKCα by the selective conventional PKC inhibitor Gö-6976 (5 μM) completely blocked the late inhibitory phase and markedly prolonged the stimulatory phase of endocytosis measured by FITC-dextran uptake. The PKCε-selective agonist carbachol (100 μM) induced prolonged stimulation of endocytosis devoid of an inhibitory phase. Actin disassembly caused by PMA was completely blocked by Gö-6850 but not by Gö-6976, implicating PKCε as the key isoform responsible for actin disruption. The Ca2+ agonist thapsigargin (5 μM) induced early activation of PKCα when added simultaneously with PMA. This early activation of PKCα blocked the ability of PMA to remodel basolateral F-actin and abolished the stimulatory phase of basolateral endocytosis. Activation of PKCα stabilizes F-actin and thereby opposes the effect of PKCε on membrane remodeling in T84 cells.

PKC-ε regulates basolateral endocytosis in human T84 intestinal epithelia: role of F-actin and MARCKS

1999 ◽  
Vol 277 (6) ◽  
pp. C1239-C1249 ◽  
Author(s):  
Jaekyung Cecilia Song ◽  
Bruce J. Hrnjez ◽  
Omid C. Farokhzad ◽  
Jeffrey B. Matthews
Keyword(s):  
Membrane Trafficking ◽  
Mammalian Cells ◽  
Basolateral Membrane ◽  
Phosphorylation Site ◽  
Fluid Phase ◽  
Cytochalasin D ◽  
Pkc Inhibitor ◽  
Intestinal Epithelia ◽  
Stimulation Of

Protein kinase C (PKC) and the actin cytoskeleton are critical effectors of membrane trafficking in mammalian cells. In polarized epithelia, the role of these factors in endocytic events at either the apical or basolateral membrane is poorly defined. In the present study, phorbol 12-myristate 13-acetate (PMA) and other activators of PKC selectively enhanced basolateral but not apical fluid-phase endocytosis in human T84 intestinal epithelia. Stimulation of basolateral endocytosis was blocked by the conventional and novel PKC inhibitor Gö-6850, but not the conventional PKC inhibitor Gö-6976, and correlated with translocation of the novel PKC isoform PKC-ε. PMA treatment induced remodeling of basolateral F-actin. The actin disassembler cytochalasin D stimulated basolateral endocytosis and enhanced stimulation of endocytosis by PMA, whereas PMA-stimulated endocytosis was blocked by the F-actin stabilizers phalloidin and jasplakinolide. PMA induced membrane-to-cytosol redistribution of the F-actin cross-linking protein myristoylated alanine-rich C kinase substrate (MARCKS). Cytochalasin D also induced MARCKS translocation and enhanced PMA-stimulated translocation of MARCKS. A myristoylated peptide corresponding to the phosphorylation site domain of MARCKS inhibited both MARCKS translocation and PMA stimulation of endocytosis. MARCKS translocation was inhibited by Gö-6850 but not Gö-6976. The results suggest that a novel PKC isoform, likely PKC-ε, stimulates basolateral endocytosis in model epithelia by a mechanism that involves F-actin and MARCKS.

scholarly journals The role of VPS4 in ESCRT-III polymer remodeling

2019 ◽  
Vol 47 (1) ◽  
pp. 441-448 ◽  
Author(s):  
Christophe Caillat ◽  
Sourav Maity ◽  
Nolwenn Miguet ◽  
Wouter H. Roos ◽  
Winfried Weissenhorn
Keyword(s):  
Active Role ◽  
Mechanistic Models ◽  
Membrane Remodeling ◽  
Filament Formation ◽  
Enveloped Viruses ◽  
Endosomal Sorting ◽  
Membrane Fission ◽  
Dynamic Assembly ◽  
Inside Out

Abstract The endosomal sorting complex required for transport-III (ESCRT-III) and VPS4 catalyze a variety of membrane-remodeling processes in eukaryotes and archaea. Common to these processes is the dynamic recruitment of ESCRT-III proteins from the cytosol to the inner face of a membrane neck structure, their activation and filament formation inside or at the membrane neck and the subsequent or concomitant recruitment of the AAA-type ATPase VPS4. The dynamic assembly of ESCRT-III filaments and VPS4 on cellular membranes induces constriction of membrane necks with large diameters such as the cytokinetic midbody and necks with small diameters such as those of intraluminal vesicles or enveloped viruses. The two processes seem to use different sets of ESCRT-III filaments. Constriction is then thought to set the stage for membrane fission. Here, we review recent progress in understanding the structural transitions of ESCRT-III proteins required for filament formation, the functional role of VPS4 in dynamic ESCRT-III assembly and its active role in filament constriction. The recent data will be discussed in the context of different mechanistic models for inside-out membrane fission.

scholarly journals Role of Membrane Remodeling Proteins in Ultrafast Endocytosis

2019 ◽  
Vol 116 (3) ◽  
pp. 313a
Author(s):  
Sumana Raychaudhuri ◽  
Eduardo Sandoval ◽  
Shigeki Watanabe
Keyword(s):  
Membrane Remodeling

Role of facilitated diffusion of calcium by calbindin in intestinal calcium absorption

1992 ◽  
Vol 262 (2) ◽  
pp. C517-C526 ◽  
Author(s):  
J. J. Feher ◽  
C. S. Fullmer ◽  
R. H. Wasserman
Keyword(s):  
Negative Feedback ◽  
Calcium Absorption ◽  
Feedback Inhibition ◽  
Basolateral Membrane ◽  
Reaction Diffusion ◽  
Diffusion Problem ◽  
Facilitated Diffusion ◽  
Calbindin D9k ◽  
And Diffusion

Computer simulations of transcellular Ca2+ transport in enterocytes were carried out using the simulation program SPICE. The program incorporated a negative-feedback entry of Ca2+ at the brush-border membrane that was characterized by an inhibitor constant of 0.5 microM cytosolic Ca2+ concentration ([Ca2+]). The basolateral Ca(2+)-ATPase was simulated by a four-step mechanism that resulted in Michaelis-Menten kinetics with a Michaelis constant of 0.24 microM [Ca2+]. The cytosolic diffusion of Ca2+ was simulated by dividing the cytosol into 10 slabs of equal width. Ca2+ binding to calbindin-D9K was simulated in each slab, and diffusion of free Ca2+, free calbindin, and Ca(2+)-laden calbindin was simulated between each slab. The cytosolic [Ca2+] of the simulated cells was regulated within the physiological range. Calbindin-D9K reduced the cytosolic [Ca2+] gradient, increased Ca2+ entry into the cell by removing the negative-feedback inhibition of Ca2+ entry, increased cytosolic Ca2+ flow, and increased the efflux of Ca2+ across the basolateral membrane by increasing the free [Ca2+] immediately adjacent to the pump. The enhancement of transcellular Ca2+ transport was nearly linearly dependent on calbindin-D9K concentration. The values of the dissociation constant (Kd) for calbindin-D9K were previously obtained experimentally in the presence and absence of KCl. Calbindin with the Kd obtained in the presence of KCl enhanced the simulated Ca2+ transport more than with the Kd obtained in the absence of KCl. This result suggests that the physiological Kd of calbindin is optimal for the enhancement of transcellular Ca2+ transport. The simulated Ca2+ flow was less than that predicted from the "near-equilibrium" analytic solution of the reaction-diffusion problem.

Intracellular pH regulation in rabbit S3 proximal tubule: basolateral Cl-HCO3 exchange and Na-HCO3 cotransport

1990 ◽  
Vol 258 (2) ◽  
pp. F371-F381 ◽  
Author(s):  
N. L. Nakhoul ◽  
L. K. Chen ◽  
W. F. Boron
Keyword(s):  
Proximal Tubule ◽  
Intracellular Ph ◽  
Initial Rate ◽  
Ph Regulation ◽  
Basolateral Membrane ◽  
Intracellular Ph Regulation ◽  
S3 Segment ◽  
Absorbance Spectra ◽  
Rule Out

We studied the role of basolateral HCO3- transport in the regulation of intracellular pH (pHi) in the isolated perfused S3 segment of the rabbit proximal tubule. pHi was calculated from absorbance spectra of the pH-sensitive dye dimethylcarboxyfluorescein. Solutions were normally buffered to pH 7.4 at 37 degrees C with 25 mM HCO3- 5% CO2. pHi fell by approximately 0.17 when luminal [HCO3-] was lowered to 5 mM at fixed PCO2 (i.e., reducing pH to 6.8) but by approximately 0.42 when [HCO3-] in the bath (i.e., basolateral solution) was lowered to 5 mM. The pHi decrease elicited by reducing bath [HCO3-] was substantially reduced by removal of Cl- or Na+, suggesting that components of basolateral HCO3- transport are Cl- and/or Na+ dependent. We tested for the presence of basolateral Cl-HCO3 exchange by removing bath Cl-. This caused pHi to increase by approximately 0.23, with an initial rate of approximately 100 X 10(-4) pH/s. Although the initial rate of this pHi increase was not reduced by removing Na+ bilaterally, it was substantially lowered by the nominal removal of HCO3- from bath and lumen or by the addition of 0.1 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) to the bath. The results thus suggest that a Na-independent Cl-HCO3 exchanger is present at the basolateral membrane. We tested for the presence of basolateral Na-HCO3 cotransport by removing bath Na+. This caused pHi to fall reversibly by approximately 0.26 with initial rates of pHi decline and recovery being approximately 30 and approximately 41 X 10(-4) pH/s, respectively. Although the bilateral removal of Cl- had no effect on these rates, the nominal removal of HCO3- or the presence of DIDS substantially slowed the pHi changes. Thus, in addition to a Cl-HCO3 exchanger, the basolateral membrane of the S3 proximal tubule also appears to possess a Na-HCO3 cotransport mechanism. The data do not rule out the possibility of other basolateral HCO3- transporters.

Basolateral membrane H-OH-HCO3 transport in the proximal tubule

1989 ◽  
Vol 256 (5) ◽  
pp. F751-F765
Author(s):  
P. A. Preisig ◽  
R. J. Alpern
Keyword(s):  
Metabolic Acidosis ◽  
Proximal Tubule ◽  
Basolateral Membrane ◽  
Respiratory Acidosis ◽  
Cell Voltage ◽  
Transport Mechanisms ◽  
Transport Capacity ◽  
Chronic Metabolic Acidosis

This review focuses on the basolateral membrane mechanisms of H-OH-HCO3 transport in the proximal tubule. The mechanism that has the greatest transport capacity and mediates most of transepithelial H-HCO3 transport is the electrogenic, Na-3HCO3 cotransporter. This transporter has been extensively characterized in the salamander, rat, and rabbit proximal tubule, and has now been found in a number of other epithelia that effect transepithelial NaHCO3 transport. Transporter rate is sensitive to intra- and extracellular [Na], intra- and extracellular [HCO3]/pH, and cell voltage. Adaptations in transporter activity have been demonstrated in chronic metabolic acidosis and alkalosis, chronic respiratory acidosis and alkalosis, and chronic hyperfiltration. In addition to the Na-3HCO3 cotransporter, the basolateral membrane possesses both Na-dependent and -independent Cl-HCO3 exchangers, a H leak, and in the S3 proximal tubule an Na-H antiporter. The role of these H-OH-HCO3 transport mechanisms in transcellular HCO3 and Cl absorption and pHi defense is discussed.

scholarly journals The FtsZ Homolog, FszB, Inhibits Mitochondrial Dynamics in Dictyostelium discoideum

Cells ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 64 ◽  
Author(s):  
Ericka Vogel ◽  
Pristine Bay Pittman ◽  
Kari Naylor
Keyword(s):  
Dictyostelium Discoideum ◽  
Mitochondrial Dynamics ◽  
Model System ◽  
Membrane Remodeling ◽  
Positive Role ◽  
Actual Mechanism

Dictyostelium discoideum is a well-established mitochondrial model system for both disease and dynamics, yet we still do not understand the actual mechanism of mitochondrial dynamics in this system. The FtsZ proteins are known to mediate membrane remodeling events such as cytokinesis in bacteria and fission of chloroplasts; D. discoideum has two FtsZ proteins, FszA and FszB. To determine the role of these proteins in mitochondrial dynamics we overexpressed FszB-GFP and determined its effect on fission, fusion, and motility in the presence of intact and disrupted cytoskeletal filaments. Here we show that overexpression of FszB-GFP decreases mitochondrial dynamics and suggest that actin may play a positive role driving fission in the context of excessive inhibition by overexpressed FszB-GFP.

Influence of vascular and luminal hexoses on rat intestinal basolateral glucose transport

1994 ◽  
Vol 72 (4) ◽  
pp. 317-326 ◽  
Author(s):  
Raymond Tsang ◽  
Ziliang Ao ◽  
Chris Cheeseman
Keyword(s):  
Glucose Transport ◽  
Plasma Glucose ◽  
Intestinal Adaptation ◽  
Basolateral Membrane ◽  
Physiological Role ◽  
Intestinal Transport ◽  
Membrane Vesicles ◽  
Luminal Perfusion

The influence of luminal and vascular hexoses in rats on glucose transport across the jejunal basolateral membrane (BLM) was measured using isolated membrane vesicles prepared from infused animals. In vivo vascular infusions of glucose produced an increase in glucose transport across BLM vesicles. Sucrose, mannose, galactose, and fructose had no significant effect. Plasma glucose concentrations were unaffected by galactose and sucrose vascular infusions, while mannose and fructose produced a modest rise, and glucose increased plasma glucose to 20 mM. Insulin release was significantly increased by vascular infusion of glucose and fructose, while mannose produced only a small sustained rise. Sucrose and galactose had no effect. Perfusion through the lumen of the rat jejunum in vivo, for up to 4 h, with glucose, fructose, sucrose, or lactate (100 or 25 mM) produced a significant increase in the maximal rate of glucose transport (up to 4- to 5-fold) across BLMs. Galactose and mannose had no effect. Luminal glucose perfusion produced a small nonsignificant increase in glucose inhibitable cytochalasin B binding to BLM vesicles, and no change was seen in the microsomal pool of binding sites. The abundance of GLUT2 in the jejunal BLM, as determined by Western blotting, was unaffected by luminal perfusion of 100 mM glucose for 4 h. Fructose almost completely inhibited the carrier-mediated uptake of glucose in control and upregulated jejunal BLM vesicles. These results are discussed in relation to the physiological role of the upregulation of GLUT2 activity by luminal and vascular hexoses.Key words: intestinal transport, basolateral membrane, glucose transport, intestinal adaptation.

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