Physiology and Pathophysiology of Potassium Channels in Gastrointestinal Epithelia

2008 ◽  
Vol 88 (3) ◽  
pp. 1119-1182 ◽  
Author(s):  
Dirk Heitzmann ◽  
Richard Warth
Keyword(s):  
Gastrointestinal Tract ◽  
Epithelial Cells ◽  
Cell Volume Regulation ◽  
Transport Processes ◽  
Fine Tuning ◽  
Electrogenic Transport ◽  
Channel Function ◽  
Channel Expression ◽  
Important Barrier

Epithelial cells of the gastrointestinal tract are an important barrier between the “milieu interne” and the luminal content of the gut. They perform transport of nutrients, salts, and water, which is essential for the maintenance of body homeostasis. In these epithelia, a variety of K+ channels are expressed, allowing adaptation to different needs. This review provides an overview of the current literature that has led to a better understanding of the multifaceted function of gastrointestinal K+ channels, thereby shedding light on pathophysiological implications of impaired channel function. For instance, in gastric mucosa, K+ channel function is a prerequisite for acid secretion of parietal cells. In epithelial cells of small intestine, K+ channels provide the driving force for electrogenic transport processes across the plasma membrane, and they are involved in cell volume regulation. Fine tuning of salt and water transport and of K+ homeostasis occurs in colonic epithelia cells, where K+ channels are involved in secretory and reabsorptive processes. Furthermore, there is growing evidence for changes in epithelial K+ channel expression during cell proliferation, differentiation, apoptosis, and, under pathological conditions, carcinogenesis. In the future, integrative approaches using functional and postgenomic/proteomic techniques will help us to gain comprehensive insights into the role of K+ channels of the gastrointestinal tract.

scholarly journals The Important Role of Ion Transport System in Cervical Cancer

2021 ◽  
Vol 23 (1) ◽  
pp. 333
Author(s):  
Yih-Fung Chen ◽  
Meng-Ru Shen
Keyword(s):  
Cervical Cancer ◽  
Epithelial Cells ◽  
Ion Transport ◽  
Cell Volume ◽  
Volume Regulation ◽  
Gynecological Cancer ◽  
Cell Volume Regulation ◽  
Hpv Infection ◽  
Transport Processes ◽  
Transport Systems

Cervical cancer is a significant gynecological cancer and causes cancer-related deaths worldwide. Human papillomavirus (HPV) is implicated in the etiology of cervical malignancy. However, much evidence indicates that HPV infection is a necessary but not sufficient cause in cervical carcinogenesis. Therefore, the cellular pathophysiology of cervical cancer is worthy of study. This review summarizes the recent findings concerning the ion transport processes involved in cell volume regulation and intracellular Ca2+ homeostasis of epithelial cells and how these transport systems are themselves regulated by the tumor microenvironment. For cell volume regulation, we focused on the volume-sensitive Cl− channels and K+-Cl− cotransporter (KCC) family, important regulators for ionic and osmotic homeostasis of epithelial cells. Regarding intracellular Ca2+ homeostasis, the Ca2+ store sensor STIM molecules and plasma membrane Ca2+ channel Orai proteins, the predominant Ca2+ entry mechanism in epithelial cells, are discussed. Furthermore, we evaluate the potential of these membrane ion transport systems as diagnostic biomarkers and pharmacological interventions and highlight the challenges.

scholarly journals Role of Lactobacillus reuteri cell and mucus-binding protein A (CmbA) in adhesion to intestinal epithelial cells and mucus in vitro

Microbiology ◽  
2014 ◽  
Vol 160 (4) ◽  
pp. 671-681 ◽  
Author(s):  
Hanne Jensen ◽  
Stefan Roos ◽  
Hans Jonsson ◽  
Ida Rud ◽  
Stine Grimmer ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Epithelial Cells ◽  
Lactobacillus Reuteri ◽  
Intestinal Epithelial Cells ◽  
Protein A ◽  
Surface Protein ◽  
Null Mutation ◽  
Intestinal Epithelial

Lactobacillus reuteri, a symbiotic inhabitant of the gastrointestinal tract in humans and animals, is marketed as a probiotic. The ability to adhere to intestinal epithelial cells and mucus is an interesting property with regard to probiotic features such as colonization of the gastrointestinal tract and interaction with the host. Here, we present a study performed to elucidate the role of sortase (SrtA), four putative sortase-dependent proteins (SDPs), and one C-terminal membrane-anchored cell surface protein of Lactobacillus reuteri ATCC PTA 6475 in adhesion to Caco-2 cells and mucus in vitro. This included mutagenesis of the genes encoding these proteins and complementation of mutants. A null mutation in hmpref0536_10255 encoding srtA resulted in significantly reduced adhesion to Caco-2 cells and mucus, indicating involvement of SDPs in adhesion. Evaluation of the bacterial adhesion revealed that of the five putative surface protein mutants tested, only a null mutation in the hmpref0536_10633 gene, encoding a putative SDP with an LPxTG motif, resulted in a significant loss of adhesion to both Caco-2 cells and mucus. Complementation with the functional gene on a plasmid restored adhesion to Caco-2 cells. However, complete restoration of adhesion to mucus was not achieved. Overexpression of hmpref0536_10633 in strain ATCC PTA 6475 resulted in an increased adhesion to Caco-2 cells and mucus compared with the WT strain. We conclude from these results that, among the putative surface proteins tested, the protein encoded by hmpref0536_10633 plays a critical role in binding of Lactobacillus reuteri ATCC PTA 6475 to Caco-2 cells and mucus. Based on this, we propose that this LPxTG motif containing protein should be referred to as cell and mucus binding protein A (CmbA).

Fundamental role of ClC-3 in volume-sensitive Cl- channel function and cell volume regulation in AGS cells

2003 ◽  
Vol 285 (5) ◽  
pp. G938-G948 ◽  
Author(s):  
Nan Ge Jin ◽  
Jin Kyoung Kim ◽  
Dong Ki Yang ◽  
Soo Jin Cho ◽  
Jung Mogg Kim ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cell Volume ◽  
Volume Regulation ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Reversal Potential ◽  
Hypotonic Solution ◽  
Gastric Epithelial Cells ◽  
Ags Cells

Volume regulation is essential for cell function, but it is unknown which channels are involved in a regulatory volume decrease (RVD) in human gastric epithelial cells. Exposure to a hypotonic solution caused the increase in AGS cell volume, followed by the activation of a current. The reversal potential of the swelling-induced current suggested that Cl- was the primary charge carrier. The selectivity sequence for different anions was I- > Br- > Cl- > F- > gluconate. This current was inhibited by flufenamate, DIDS, tamoxifen, and 5-nitro-2-(3-phenylpropylamino)benzoate. Intracellular dialysis of three different anti-ClC-3 antibodies abolished or attenuated the Cl- current and disrupted RVD, whereas the current and RVD was unaltered by anti-ClC-2 antibody. Immunoblot studies demonstrated the presence of ClC-3 protein in Hela and AGS cells. RT-PCR analysis detected expression of ClC-3, MDR-1, and pICln mRNA in AGS cells. These results suggest a fundamental role of endogenous ClC-3 in the swelling-activated Cl- channels function and cell volume regulation in human gastric epithelial cells.

scholarly journals Fine-tuning of β-catenin in thymic epithelial cells is required for postnatal T cell development

2021 ◽  
Author(s):  
Sayumi Fujimori ◽  
Izumi Ohigashi ◽  
Hayato Abe ◽  
M Mark Taketo ◽  
Yousuke Takahama ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Epithelial Cells ◽  
T Cell Development ◽  
Cell Development ◽  
Fine Tuning ◽  
Thymic Epithelial Cells ◽  
Loss Of Function ◽  
Thymic Epithelium

In the thymus, the thymic epithelium provides a microenvironment essential for the development of functionally competent and self-tolerant T cells. Previous findings showed that modulation of Wnt/β-catenin signaling in thymic epithelial cells (TECs) disrupts embryonic thymus organogenesis. However, the role of β-catenin in TECs for postnatal T cell development remains to be elucidated. Here, we analyzed gain-of function (GOF) and loss-of-function (LOF) of β-catenin highly specific in TECs. We found that GOF of β-catenin in TECs results in severe thymic dysplasia and T cell deficiency beginning from the embryonic period. By contrast, LOF of β-catenin in TECs reduces the number of cortical TECs and thymocytes modestly and only postnatally. These results indicate that fine-tuning of β-catenin expression within a permissive range is required for TECs to generate an optimal microenvironment to support postnatal T cell development.

Events at the Host-Microbial Interface of the Gastrointestinal Tract I. Adaptation to a microbial world: role of epithelial bactericidal/permeability-increasing protein

2005 ◽  
Vol 288 (4) ◽  
pp. G593-G597 ◽  
Author(s):  
Geraldine Canny ◽  
Sean P. Colgan
Keyword(s):  
Gastrointestinal Tract ◽  
Epithelial Cells ◽  
Inflammatory Responses ◽  
Systemic Disease ◽  
Phenotypic Characteristics ◽  
Microbial World ◽  
Microbial Products ◽  
Insight Into

Epithelial cells of many mucosal organs have adapted to coexist with microbes and microbial products. In general, most studies suggest that epithelial cells benefit from interactions with commensal microorganisms present at the lumenal surface. However, potentially injurious molecules found in this microenvironment also have the capacity to elicit local inflammatory responses and even systemic disease. In this environment, the epithelium has evolved effective mechanisms to cope with microbial products and to provide appropriate responses to potential pathogens. Although our understanding of these mechanisms is clearly in its infancy, a number of recent findings provide insight into phenotypic characteristics that allow for this discrimination. Here, we briefly review some of these mechanisms, with particular attention to epithelial expression of the anti-infective molecule bactericidal/permeability-increasing protein.

Effect of Calcium on the Growth and Differentiation of Cultured Rat Esophageal Epithelial Cells

1982 ◽  
Vol 40 ◽  
pp. 132-133
Author(s):  
W.T. Gunning ◽  
M.R. Marino ◽  
M.S. Babcock ◽  
G.D. Stoner
Keyword(s):  
Epithelial Cells ◽  
Cell Types ◽  
Replication Rate ◽  
Enzymatic Dissociation ◽  
Growth Assay ◽  
Epidermal Growth ◽  
Fetal Bovine ◽  
Esophageal Epithelial Cells ◽  
Cellular Replication

The role of calcium in modulating cellular replication and differentiation has been described for various cell types. In the present study, the effects of Ca++ on the growth and differentiation of cultured rat esophageal epithelial cells was investigated.Epithelial cells were isolated from esophagi taken from 8 week-old male CDF rats by the enzymatic dissociation method of Kaighn. The cells were cultured in PFMR-4 medium supplemented with 0.25 mg/ml dialyzed fetal bovine serum, 5 ng/ml epidermal growth factor, 10-6 M hydrocortisone 10-6 M phosphoethanolamine, 10-6 M ethanolamine, 5 pg/ml insulin, 5 ng/ml transferrin, 10 ng/ml cholera toxin and 50 ng/ml garamycin at 36.5°C in a humidified atmosphere of 3% CO2 in air. At weekly intervals, the cells were subcultured with a solution containing 1% polyvinylpyrrolidone, 0.01% EGTA, and 0.05% trypsin. After various passages, the replication rate of the cells in PFMR-4 medium containing from 10-6 M to 10-3 M Ca++ was determined using a clonal growth assay.

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