Effects of phloretin and theophylline on 3-O-methylglucose transport by intestinal epithelial cells

1978 ◽  
Vol 234 (3) ◽  
pp. C64-C72 ◽  
Author(s):  
J. Randles ◽  
G. A. Kimmich
Keyword(s):  
Epithelial Cells ◽  
Transport System ◽  
Intestinal Epithelial Cells ◽  
Sugar Transport ◽  
Inhibitory Effect ◽  
Metabolic Effects ◽  
Transport Systems ◽  
Facilitated Diffusion ◽  
Intestinal Epithelial ◽  
Gradient Enhancement

Phloretin and theophylline each exert an immediate inhibitory effect on the Na+-independent, facilitated-diffusion transport system for sugar associated with intestinal epithelial cells. Phloretin inhibits approximately 50% more of the total Na+-independent sugar flux than theophylline. Neither agent has an immediate effect on the Na+-dependent, concentrative sugar transport system, although preincubation of the cells with phloretin causes a significant inhibition. The slowly developing effect is correlated with a decrease in cellular adenosine triphosphate (ATP) and an elevation of intracellular Na+. Other agents which elevate cell Na+ also inhibit Na+-dependent sugar influx, even if ATP levels are not depleted. On the other hand, if ATP is depleted by phloretin under conditions in which the cells do not gain Na+, the inhibitory effect on Na+-dependent sugar flux tends to disappear. The slow-onset phloretin effects are due to transinhibition of the Na+-dependent sugar carrier by cellular Na+. When the passive sugar carrier is inhibited by phloretin or theophylline, the concentrative system can establish an enhanced sugar gradient. Because of the secondary metabolic effects of phloretin, theophylline induces a greater gradient enhancement despite its more limited effect on the passive sugar-transport system. Sugar gradients as large as 20-fold are induced by theophylline, in contrast to 12-fold gradients observed in the presence of phloretin and approximately 7- to 8-fold for untreated cells. These results are discussed in terms of conceptual questions regarding the energetics of Na+-dependent transport systems.

Energetics of sugar transport by isolated intestinal epithelial cells: effects of cytochalasin B

1979 ◽  
Vol 237 (1) ◽  
pp. C56-C63 ◽  
Author(s):  
G. A. Kimmich ◽  
J. Randles
Keyword(s):  
Steady State ◽  
Epithelial Cells ◽  
Transport System ◽  
Cytochalasin B ◽  
Intestinal Epithelial Cells ◽  
Sugar Accumulation ◽  
Facilitated Diffusion ◽  
Intestinal Epithelial ◽  
Passive System ◽  
Concentration Gradients

The capability of isolated intestinal epithelial cells to establish concentration gradients of 3-O-methylglucose (3-OMG) by a Na+-dependent transport system is limited by concomitant function of a Na+-independent, facilitated diffusion transport system. Monosaccharides accumulated by the active system are continuously lost via the passive system, which acts to lower steady-state sugar gradients maintained by the cell. Cytochalasin B is a potent inhibitor of the passive system and allows the cells to establish a sugar gradient that is much higher than normal. When extracellular [3-;OMG] is 1 mM, cytochalasin induces sugar accumulation ratios of 30-;fold (+/- phlorizin) in contrast to control ratios of approximately 10-;fold. When [3-;OMG] is 0.1 mM, cytochalasin (0.1 mM) induces 40-;fold accumulation ratios. When changes in extracellular sugar concentration are considered, steady-state concentration gradients observed are 70-;fold. For a Na:sugar coupling stoichiometry of 1:1, gradients of this magnitude represent the approximate theoretical maximum for a transport system driven exclusively by the transmembrane electrochemical potential for Na+.

Regulation of Na+-dependent sugar transport in intestinal epithelial cells by exogenous ATP

1980 ◽  
Vol 238 (5) ◽  
pp. C177-C183 ◽  
Author(s):  
G. Kimmich ◽  
J. Randles
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Sugar Transport ◽  
Late Effect ◽  
Nucleoside Triphosphate ◽  
Intestinal Epithelial ◽  
Early Effect ◽  
Adenine Ring ◽  
Transport Inhibition ◽  
Gradient Enhancement

Exogenous ATP (1 mM) exerts a dramatic biphasic effect on the accumulation of 100 micro M 3-O-methylglucose by isolated intestinal epithelial cells. The initial effect ensues approximately 15 s after exposure and inhibits 80% of the undirectional sugar influx. Cellular phosphatases totally degrade the added ATP within a period of 20 min leading to a reactivation of transport capability. The cells exposed to ATP ultimately establish a concentration gradient of sugar about twice that observed for control cells. Pyrophosphate (10 mM) delays the degradation of added ATP and prolongs the interval of transport inhibition. The late effect of gradient enhancement is still observed. No other nucleoside triphosphate induces the early inhibition of transport, but ADP is approximately two-thirds as effective as ATP. AMP and other molecules containing the adenine ring system can cause the late effect of gradient enhancement without causing an early transport inhibition. Because rotenone-treated ATP-depleted cells also show an ATP-induced inhibition of sugar influx, it seems likely that the early effect represents a direct modification of carrier capability rather than an effect mediated via an alteration of cellular energetics.

Inhibitory effect of carnosine on interleukin-8 production in intestinal epithelial cells through translational regulation

Cytokine ◽  
2008 ◽  
Vol 42 (2) ◽  
pp. 265-276 ◽  
Author(s):  
Dong Ok Son ◽  
Hideo Satsu ◽  
Yoshinobu Kiso ◽  
Mamoru Totsuka ◽  
Makoto Shimizu
Keyword(s):  
Epithelial Cells ◽  
Translational Regulation ◽  
Intestinal Epithelial Cells ◽  
Inhibitory Effect ◽  
Interleukin 8 ◽  
Intestinal Epithelial

scholarly journals JunD enhances miR-29b levels transcriptionally and posttranscriptionally to inhibit proliferation of intestinal epithelial cells

2015 ◽  
Vol 308 (10) ◽  
pp. C813-C824 ◽  
Author(s):  
Tongtong Zou ◽  
Jaladanki N. Rao ◽  
Lan Liu ◽  
Lan Xiao ◽  
Hee Kyoung Chung ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Transcription Factor ◽  
Epithelial Cells ◽  
Transcriptional Activation ◽  
Binding Sites ◽  
Intestinal Epithelial Cells ◽  
Inhibitory Effect ◽  
Microrna Expression ◽  
Intestinal Epithelial ◽  
Gut Epithelium

Through its actions as component of the activating protein-1 (AP-1) transcription factor, JunD potently represses cell proliferation. Here we report a novel function of JunD in the regulation of microRNA expression in intestinal epithelial cells (IECs). Ectopically expressed JunD specifically increased the expression of primary and mature forms of miR-29b, whereas JunD silencing inhibited miR-29b expression. JunD directly interacted with the miR-29b1 promoter via AP-1-binding sites, whereas mutation of AP-1 sites from the miR-29b1 promoter prevented JunD-mediated transcriptional activation of the miR-29b1 gene. JunD also enhanced formation of the Drosha microprocessor complex, thus further promoting miR-29b biogenesis. Cellular polyamines were found to regulate miR-29b expression by altering JunD abundance, since the increase in miR-29b expression levels in polyamine-deficient cells was abolished by JunD silencing. In addition, miR-29b silencing prevented JunD-induced repression of IEC proliferation. Our findings indicate that JunD activates miR-29b by enhancing its transcription and processing, which contribute to the inhibitory effect of JunD on IEC growth and maintenance of gut epithelium homeostasis.

Some factors affecting the adherence of probiotic Propionibacterium acidipropionici CRL 1198 to intestinal epithelial cells

2002 ◽  
Vol 48 (5) ◽  
pp. 449-457 ◽  
Author(s):  
Gabriela Zárate ◽  
Vilma Morata De Ambrosini ◽  
Adriana Perez Chaia ◽  
Silvia González
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Divalent Cations ◽  
Metabolic Effects ◽  
Bacterial Cells ◽  
Intestinal Epithelial ◽  
Propionibacterium Acidipropionici ◽  
Sodium Metaperiodate

Adhesion to the intestinal mucosa is generally considered an important property of probiotic microorganisms and has been related to many of their health benefits. This study investigated some factors that could affect or be involved in the adherence of Propionibacterium acidipropionici CRL 1198, a dairy strain with suggested probiotic effects and high adherence in vitro and in vivo to intestinal epithelial cells. In vitro adhesion of propionibacteria was decreased by gastric digestion but not affected by bile and pancreatic enzymes. Adherence was also decreased by pretreatment of bacterial cells with protease, sodium metaperiodate, and trichloroacetic acid, revealing that different features of the cell surface, like protein factors, carbohydrates, and teichoic acids, are involved in the process. Adherence to intestinal epithelial cells was enhanced by calcium and was dependent on other divalent cations. Adhesion to intestinal mucus was also demonstrated. The results should explain the metabolic effects in the host previously obtained with this strain and support the potential of Propionibacterium for development of new probiotics.Key words: propionibacteria, adhesion, probiotics.

NF-κB-mediated IAP expression induces resistance of intestinal epithelial cells to apoptosis after polyamine depletion

2004 ◽  
Vol 286 (5) ◽  
pp. C1009-C1018 ◽  
Author(s):  
Tongtong Zou ◽  
Jaladanki N. Rao ◽  
Xin Guo ◽  
Lan Liu ◽  
Huifang M. Zhang ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Caspase 3 ◽  
Intestinal Epithelial Cells ◽  
Specific Inhibitor ◽  
Inhibitory Effect ◽  
Intestinal Epithelial ◽  
Tnf Α ◽  
Induced Apoptosis ◽  
Necrosis Factor ◽  
Active Caspase

Apoptosis plays a crucial role in maintenance of intestinal epithelial integrity and is highly regulated by numerous factors, including cellular polyamines. We recently showed that polyamines regulate nuclear factor (NF)-κB activity in normal intestinal epithelial (IEC-6) cells and that polyamine depletion activates NF-κB and promotes resistance to apoptosis. The current study went further to determine whether the inhibitors of apoptosis (IAP) family of proteins, c-IAP2 and XIAP, are downstream targets of activated NF-κB and play a role in antiapoptotic activity of polyamine depletion in IEC-6 cells. Depletion of cellular polyamines by α-difluoromethylornithine not only activated NF-κB activity but also increased expression of c-IAP2 and XIAP. Specific inhibition of NF-κB by the recombinant adenoviral vector containing IκBα superrepressor (Ad Iκ BSR) prevented the induction of c-IAP2 and XIAP in polyamine-deficient cells. Decreased levels of c-IAP2 and XIAP proteins by inactivation of NF-κB through Ad Iκ BSR infection or treatment with the specific inhibitor Smac also overcame the resistance of polyamine-depleted cells to apoptosis induced by the combination of tumor necrosis factor (TNF)-α and cycloheximide (CHX). Although polyamine depletion did not alter levels of procaspase-3 protein, it inhibited formation of the active caspase-3. Decreased levels of c-IAP2 and XIAP by Smac prevented the inhibitory effect of polyamine depletion on the cleavage of procaspase-3 to the active caspase-3. These results indicate that polyamine depletion increases expression of c-IAP2 and XIAP by activating NF-κB in intestinal epithelial cells. Increased c-IAP2 and XIAP after polyamine depletion induce the resistance to TNF-α/CHX-induced apoptosis, at least partially, through inhibition of the caspase-3 activity.

Functional involvement of RFVT3/SLC52A3 in intestinal riboflavin absorption

2014 ◽  
Vol 306 (2) ◽  
pp. G102-G110 ◽  
Author(s):  
Hiroki Yoshimatsu ◽  
Atsushi Yonezawa ◽  
Yoshiaki Yao ◽  
Kumiko Sugano ◽  
Shunsaku Nakagawa ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Small Intestine ◽  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Biological Membrane ◽  
Transport Systems ◽  
Intestinal Epithelial ◽  
T84 Cells ◽  
Functional Involvement ◽  
Apical Membranes

Riboflavin, also known as vitamin B2, is transported across the biological membrane into various organs by transport systems. Riboflavin transporter RFVT3 is expressed in the small intestine and has been suggested to localize in the apical membranes of the intestinal epithelial cells. In this study, we investigated the functional involvement of RFVT3 in riboflavin absorption using intestinal epithelial T84 cells and mouse small intestine. T84 cells expressed RFVT3 and conserved unidirectional riboflavin transport corresponding to intestinal absorption. Apical [3H]riboflavin uptake was pH-dependent in T84 cells. This uptake was not affected by Na+ depletion at apical pH 6.0, although it was significantly decreased at apical pH 7.4. The [3H]riboflavin uptake from the apical side of T84 cells was prominently inhibited by the RFVT3 selective inhibitor methylene blue and significantly decreased by transfection of RFVT3-small-interfering RNA. In the gastrointestinal tract, RFVT3 was expressed in the jejunum and ileum. Mouse jejunal and ileal permeabilities of [3H]riboflavin were measured by the in situ closed-loop method and were significantly reduced by methylene blue. These results strongly suggest that RFVT3 would functionally be involved in riboflavin absorption in the apical membranes of intestinal epithelial cells.

Transport of thiamine in human intestine: mechanism and regulation in intestinal epithelial cell model Caco-2

1999 ◽  
Vol 277 (4) ◽  
pp. C645-C651 ◽  
Author(s):  
Hamid M. Said ◽  
Alvaro Ortiz ◽  
Chandira K. Kumar ◽  
Nabendu Chatterjee ◽  
Pradeep K. Dudeja ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Epithelial Cells ◽  
Protein Tyrosine Kinase ◽  
Intestinal Epithelial Cells ◽  
Cell Model ◽  
Transport Systems ◽  
Organic Cations ◽  
Maximal Velocity ◽  
Intestinal Epithelial

The present study examined the intestinal uptake of thiamine (vitamin B1) using the human-derived intestinal epithelial cells Caco-2 as an in vitro model system. Thiamine uptake was found to be 1) temperature and energy dependent and occurred with minimal metabolic alteration; 2) pH sensitive; 3) Na+independent; 4) saturable as a function of concentration with an apparent Michaelis-Menten constant of 3.18 ± 0.56 μM and maximal velocity of 13.37 ± 0.94 pmol ⋅ mg protein−1⋅ 3 min−1; 5) inhibited by the thiamine structural analogs amprolium and oxythiamine, but not by unrelated organic cations tetraethylammonium, N-methylnicotinamide, and choline; and 6) inhibited in a competitive manner by amiloride with an inhibition constant of 0.2 mM. The role of specific protein kinase-mediated pathways in the regulation of thiamine uptake by Caco-2 cells was also examined using specific modulators of these pathways. The results showed possible involvement of a Ca2+/calmodulin (CaM)-mediated pathway in the regulation of thiamine uptake. No role for protein kinase C- and protein tyrosine kinase-mediated pathways in the regulation of thiamine uptake was evident. These results demonstrate the involvement of a carrier-mediated system for thiamine uptake by Caco-2 intestinal epithelial cells. This system is Na+independent and is different from the transport systems of organic cations. Furthermore, a CaM-mediated pathway appears to play a role in regulating thiamine uptake in these cells.

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