Colonic epithelial cells

Rendon, M. A., Saldana, Z., Erdem, A. L., Monteiro-Neto, V., Vazquez, A., Kaper, J. B., Puente, J. L., and Giron, J. A. (2007). Commensal and pathogenic Escherichia coli use a common pilus adherence factor for epithelial cell colonization. Proc. Natl. Acad. Sci. USA 104,10637-10642. 

ENaC is located in the apical membrane of polarized epithelial cells where it mediates Na+ transport across tight epithelia [3], The most important tight epithelia expressing ENaC include the distal nephron of the kidney, the respiratory epithelium, and the distal colon. The basic function of ENaC in polarized epithelial cells is to allow vectorial transcellular transport of Na+ ions. This transepithelial Na+ transport through a cell involves... 

HAGUE A, DIAZ G D, HICKS D J, KRAJEWSKI s, REED c, PARASKEVA c (1997) Blc-2 and bak may play a pivotal role in sodium butyrate-induced apoptosis in colonic epithelial cells however over expression of blc-2 does not protect against bak-mediated apoptosis. Int. J. Cancer 72 898-905. 

Studies by Hudson et al, (2000) have demonstrated the presence of eight polyphenols in rice bran by using high-pressure liquid chromatography. They are protocatechuic acid, p-coumaric acid, ferulic acid, sinapic aci vanillic acid, caffeic acid, which is a methoxycirmamic acid derivative, and tricin. The effect of these polyphenols on cell viability and on the colony-forming ability of human-derived MDA MB 468 and HBL 100 breast cells, colon-derived SW 480 and human colonic epithelial cells was assessed. These authors concluded that rice bran polyphenols have putative cancer chemopreventive properties. 

The physiological role of the ICOR is not clear and may be heterogeneous in the various tissues. In the thick ascending limb of the loop of Henle this channel appears to serve as the exit for CP at the basal cell pole [16,65,66], This conductive mechanism, therefore, is required for the reabsorption of Na and CP by this segment of the nephron [16]. In the rectal gland of Squalus acanthias a very similar channel is utilized for Na" and CP secretion. In these latter cells the CP-channel is present in the luminal membrane and is controlled by cytosolic cAMP [15,56,71]. It has been claimed that this kind of channel is also responsible for the secretion of CP in the colonic crypt cell, in colonic carcinoma cells and in respiratory epithelial cells [17,19,20,22]. Recent data have cast some doubt on this concept ... 

CP-channels with even smaller conductance have been described for the lacrimal and other exocrine glands [76,77]. These channels have a conductance of 1-2 pS. Unlike the ICOR-channel they appear to be blocked by millimolar concentrations of furosemide [77]. Most recent and only partially published data from my own laboratory obtained with the above modified nystatin technique [50,133,134] indicate that the respiratory epithelial cells and colonic carcinoma cells possess these types of small CP channels, and that these channels are involved in hormonal regulation of CP-conductance (cf. section 5). These CP-channels are regulated by cytosolic Ca. Hormonally induced increases in cytosolic Ca lead to an abrupt increase in the probability of these small CP-channels being open, yet they have no effect on the ICOR-channel. Data of this kind reinforce that the physiological importance of these small CP-channels may have been grossly underestimated. 

It has been known for some time that the Cl -conductance of epithelial cells can, in addition to its regulation via cAMP, be enhanced by increases in cytosolic Ca " (cf. Fig. 3). This has been shown with Ca -ionophores [120,121] or with hormones increasing cytosolic Ca such as carbachol, neurotensin, ATP, etc. [50,103,104]. Usually these agonists have dual effects. They increase the Cl - as well as the K" -conductance [104]. Stubs et al. [122] have shown that CF cells still increase their Cl -conductance in response to ATP. Another mechanism of Cl -channel activation has been described in whole-cell patches of colonic carcinoma and RE cells [123,124] when the cells are exposed to hypotonic media they swell and increase their Cl -conductance. This is a rather general phenomenon which is present in a lot of cells [11]. In their effort to reduce cell volume in hypotonic media (regulatory... 

Cell culture Damage to small intestinal epithelial cells by XO can be prevented by SOD and desferrioxamine (Ma et al., 1991), whilst that to rat enterocytes, CaCo cells or rabbit colonic epithelial cells by XO can be decreased by catalase (Baker and Baker, 1990 Baker and Campbell, 1991 Kawabe etal., 1992). 

Craven, P.A., Pfanstiel, J., Saito, R. and DeRubertis, F.R. (1987). Actions of sulfasalazine and 5-aminosalisylic acid as reactive oxygen scavengers in the suppression of bile acid-induced increases in colonic epithelial cell loss and proliferative activity. Gastroenterology 92, 1998-2008. 

Kawabe, T., Hiraishi, H., Hata, Y., Razandi, M., Teranoa, T. and Ivey, K.J. (1992). Reactive oxygen metabolites mediate cytotoxicity to cultured colonic epithelial cells. Gastroen-terolc 102, A644. 

Fiorelli, G. Picariello, L. Martineti, V. Tonelli, F. Brandi, M. L. Estrogen synthesis in human colon cancer epithelial cells. J. Steroid Biochem. Mol. Biol. 1999, 71, 223-230. 

An alteration in the inflammatory response regulated by intestinal epithelial cells may also contribute to development of IBD. This may involve inappropriate processing of antigens presented to the GI epithelial cells.3 The inflammatory response in IBD may actually be directed at bacteria that normally colonize... 

The passage of fluids into and out of the colon is regulated by epithelial cells. In IBS, the colonic lining (epithelium) appears to work properly. However, increased movement of the contents in the colon can overwhelm its absorptive capacity. 

Enhanced binding of Candida to epithelial cells due to hyperglycemia asymptomatic colonization is more common in patients with diabetes elevated sugar levels may cause conversion to symptomatic infection... 

Four major tissue layers, from the lumen outward, form the large intestine the mucosa, submucosa, muscularis externa, and serosa (Fig. 88-2). Complete replacement of surface epithelial cells occurs approximately weekly, with the total number of epithelial cells remaining constant in normal colonic tissue. As patients age, abnormal cells accumulate on the surface epithelium and protrude into the stream of fecal matter their contact with fecal mutagens can lead to further cell mutations and eventual adenoma formation.4... 

Figure 2 Comparison of intestinal epithelial cells in culture and in situ. (A) Human colon Caco-2 cells grown in culture for 16 days on a semiporous filter. (B) Epithelial layer of rat jejunum. AP, apical or luminal membrane B, basal or abluminal membrane BM, basement membrane G, goblet cell LS, lateral space mv, microvilli Nu, nucleus TJ, tight junction. Bars equal 10 pm. 

Another way to increase the entry of Ca2+ across the plasma membrane is to hyperpolarize the plasma membrane by elevating active ion transport. Fischer et al. [130] demonstrated that hyperpolarization of colonic epithelial cells (HT-29) with carbachol elevates the intracellular levels of Ca2+, [Ca2+]i while depolarization with gramicidin D or elevation of K+ in the bathing fluid reverses it. Treatment with 0.1 mM carbachol produced a spontaneous increase in [Ca2+]i from 63 nM to 901 nM. This lasted for about 3 min, beyond which a plateau level of 309 nM was maintained. While the initial Ca2+ transient was present in Ca2+-free medium containing 0.1 mM EGTA, the plateau phase was suppressed to baseline levels, suggesting that carbachol initially releases Ca2+ from the intracellular stores and subsequently increases the Ca2+ entry across the plasma membrane. In cells hyperpolarized with carbachol, induction of depolarization by ele-... 

D Chang, NL Kushman, DC Dawson. (1991). Intracellular pH regulates basolateral K+ and CD conductances in colonic epithelial cells by modulating Ca2+ activation. J Gen Physiol 98 183-196. 

Jung, H.C., Eckmann, L., Yang, S.K, Panja, A., Fierer, J., Morzyckawroblewska, E. and Kagnoff, M.F. (1995) A distinct array of proinflammatory cytokines is expressed in human colon epithelial cells in response to bacterial invasion. Journal of Clinical Investigation 95, 55-65. 

Scheuerermaly, C.C., Eckmann, L., Kagnoff, M.F., Falco, M.T. and Maly, F.E. (1994) Colonic epithelial cell lines as a source of interleukin-8 stimulation by inflammatory cytokines and bacterial lipopolysaccharide. Immunology 81, 85-91. 

Song, F., Ito, K., Denning, T.L., Kuninger, D., Papaconstantinou, J., Gourley, W., Klimpel, G., Balish, E., Hokanson, J. and Ernst, P.B. (1999) Expression of the neutrophil chemokine KC in the colon of mice with enterocolitis and by intestinal epithelial cell lines effects of flora and proinflammatory cytokines. Journal of Immunology 162, 2275-2280. 

The paracellular pathway, between the epithelial cells, is both size- (MW, volume) and charge-dependent [60, 109, 110]. In general, compounds that are limited to paracellular transport are not efficiently absorbed due to the small available absorptive area and the restriction by tight junctions. The molecular weight cut-off seems to be around 400 g mol-1 and 300 g mol-1 for the small and large intestine respectively, and 300 g mol-1 for the Caco-2 cell monolayers [60], which shows the more colonic nature of the Caco-2 monolayer model. Compounds with a... 

Colon adenocarcinoma epithelial cell line Rat renal proximal tubular epithelial cell line Tetrahydrofuranyl Valacyclovir hydrolase... 

P-glycoprotein is not only expressed in tumor cells, but also in cells of several healthy tissues. In liver it was detected in the biliary canalicular surface of hepato-cytes and the apical surface of small biliary ductules. In the small intestine and colon, it is localized in the apical surface of columnar epithelial cells, and in kidneys it is found in the brush border membrane of proximal tubules. Moreover, it is detectable on the apical surface of small ductules in the pancreas and on the surface of cells in the medulla and cortex of adrenals [2]. 

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