Effects of modulation of tyrosine phosphorylation on brush border enzyme activity in human Caco-2 intestinal epithelial cells

1998 ◽  
Vol 292 (3) ◽  
pp. 553-562 ◽  
Author(s):  
M. D. Basson ◽  
Nancy J. Emenaker ◽  
Zaihan Rashid
Keyword(s):  
Enzyme Activity ◽  
Epithelial Cells ◽  
Tyrosine Phosphorylation ◽  
Brush Border ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Brush Border Enzyme

The Fine-Structural Organization of the Brush Border of Intestinal Epithelial Cells

1971 ◽  
Vol 8 (3) ◽  
pp. 573-599
Author(s):  
T. M. MUKHERJEE ◽  
L. A. STAEHELIN
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Brush Border ◽  
Intestinal Epithelial Cells ◽  
Membrane Surface ◽  
Intestinal Epithelial ◽  
The Core ◽  
Unit Structure ◽  
Terminal Web ◽  
Freeze Etching

The fine structure of the brush border of intestinal epithelial cells of the mouse has been studied with both normal sectioning and freeze-etching techniques. Freeze-etching reveals the plasma membrane of the microvilli as consisting of a continuous layer, that is split during the cleaving process, in which numerous particles, 5-9 nm in diameter, are embedded, while other particle-like structures, with diameters of 7-10 nm, appear attached to the true outer membrane surface. The mucopolysaccharide surface coats of the microvilli show up more clearly in sectioned material than in freeze-etched specimens. Inside each microvillus 2 different filament systems can be demonstrated: (1) bundles of fairly closely packed and straight core microfilaments, which lead into the tip of the microvillus, and (2) short cross-filaments. Under suitable conditions the core microfilaments display a sub-unit structure with a repeating distance of approximately 6 nm. The diameter of a microfilament can vary along its length from 6 to 11 nm. Two strands of globular particles wound helically around each other seem to make up each microfilament. These and other data support the idea that the core microfilaments are actin-like. No substructure has been found on the cross-filaments, which have an orientation approximately radial to the axis of the microvilli and seem to be attached at one end to the core microfilaments and at the other to the inner surface of the microvillous membrane. The interwoven terminal web filaments also show no substructure. They form a continuous flexible platform-like structure into which the bundles of core microfilaments extend. Some terminal web filaments appear attached to the plasma membrane between the microvilli. It is suggested that the core microfilaments represent mechanical supporting elements and that the terminal web and cross-filaments are tensile elements of the brush border. In addition all 3 filament systems may also be involved in possible contractile movements of the microvilli.

scholarly journals Unique Regulation of Enterocyte Brush Border Membrane Na-Glutamine and Na-Alanine Co-Transport by Peroxynitrite during Chronic Intestinal Inflammation

2019 ◽  
Vol 20 (6) ◽  
pp. 1504 ◽  
Author(s):  
Subha Arthur ◽  
Palanikumar Manoharan ◽  
Shanmuga Sundaram ◽  
M Rahman ◽  
Balasubramanian Palaniappan ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Intestinal Inflammation ◽  
Intestinal Epithelial Cells ◽  
Rabbit Model ◽  
Intestinal Epithelial ◽  
Mechanism Of Inhibition ◽  
Chronic Intestinal Inflammation

Na-amino acid co-transporters (NaAAcT) are uniquely affected in rabbit intestinal villus cell brush border membrane (BBM) during chronic intestinal inflammation. Specifically, Na-alanine co-transport (ASCT1) is inhibited secondary to a reduction in the affinity of the co-transporter for alanine, whereas Na-glutamine co-transport (B0AT1) is inhibited secondary to a reduction in BBM co-transporter numbers. During chronic intestinal inflammation, there is abundant production of the potent oxidant peroxynitrite (OONO). However, whether OONO mediates the unique alteration in NaAAcT in intestinal epithelial cells during chronic intestinal inflammation is unknown. In this study, ASCT1 and B0AT1 were inhibited by OONO in vitro. The mechanism of inhibition of ASCT1 by OONO was secondary to a reduction in the affinity of the co-transporter for alanine, and secondary to a reduction in the number of co-transporters for B0AT1, which were further confirmed by Western blot analyses. In conclusion, peroxynitrite inhibited both BBM ASCT1 and B0AT1 in intestinal epithelial cells but by different mechanisms. These alterations in the villus cells are similar to those seen in the rabbit model of chronic enteritis. Therefore, this study indicates that peroxynitrite may mediate the inhibition of ASCT1 and B0AT1 during inflammation, when OONO levels are known to be elevated in the mucosa.

Corticosteroid receptors and 11β-hydroxysteroid dehydrogenase isoforms in rat intestinal epithelia

1999 ◽  
Vol 277 (3) ◽  
pp. G541-G547 ◽  
Author(s):  
Karen E. Sheppard ◽  
Kevin X. Z. Li ◽  
Dominic J. Autelitano
Keyword(s):  
Enzyme Activity ◽  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Reductase Activity ◽  
Distal Colon ◽  
Hydroxysteroid Dehydrogenase ◽  
Intestinal Epithelial ◽  
Rnase Protection ◽  
Intestinal Epithelia ◽  
Corticosteroid Receptors

To evaluate the potential roles that both receptors and enzymes play in corticosteroid regulation of intestinal function, we have determined glucocorticoid receptor (GR), mineralocorticoid receptor (MR), and 11β-hydroxysteroid dehydrogenase (11β-HSD) expression in intestinal epithelial cells. GR and MR mRNA and receptor binding were ubiquitously expressed in epithelial cells, with receptor levels higher in ileum and colon than jejunum and duodenum. RNase protection analysis showed that 11β-HSD1 was not expressed in intestinal epithelial cells, and enzyme activity studies detected no 11-reductase activity. 11β-HSD2 mRNA and protein were demonstrated in ileal and colonic epithelia; both MR and GR binding increased when enzyme activity was inhibited with carbenoxolone. Duodenal and jejunal epithelial cells showed very little 11β-HSD2 mRNA and undetectable 11β-HSD2 protein; despite minor (<7%) dehydrogenase activity in these cells, enzyme activity did not alter binding of corticosterone to either MR or GR. These findings demonstrate the ubiquitous but differential expression of MR and GR in intestinal epithelia and that 11β-HSD2 modulates corticosteroid binding to both MR and GR in ileum and proximal and distal colon but not in duodenum or jejunum.

scholarly journals Intermediate Filaments Interact with Dormant Ezrin in Intestinal Epithelial Cells

2005 ◽  
Vol 16 (9) ◽  
pp. 4096-4107 ◽  
Author(s):  
Flavia A. Wald ◽  
Andrea S. Oriolo ◽  
M. Llanos Casanova ◽  
Pedro J.I. Salas
Keyword(s):  
Epithelial Cells ◽  
Intermediate Filaments ◽  
Brush Border ◽  
Antisense Rna ◽  
Apical Membrane ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Undifferentiated Cells ◽  
Responsive Element

Ezrin connects the apical F-actin scaffold to membrane proteins in the apical brush border of intestinal epithelial cells. Yet, the mechanisms that recruit ezrin to the apical domain remain obscure. Using stable CACO-2 transfectants expressing keratin 8 (K8) antisense RNA under a tetracycline-responsive element, we showed that the actin-ezrin scaffold cannot assemble in the absence of intermediate filaments (IFs). Overexpression of ezrin partially rescued this phenotype. Overexpression of K8 in mice also disrupted the assembly of the brush border, but ezrin distributed away from the apical membrane in spots along supernumerary IFs. In cytochalasin D-treated cells ezrin localized to a subapical compartment and coimmunoprecipitated with IFs. Overexpression of ezrin in undifferentiated cells showed a Triton-insoluble ezrin compartment negative for phospho-T567 (dormant) ezrin visualized as spots along IFs. Pulse-chase analysis showed that Triton-insoluble, newly synthesized ezrin transiently coimmunoprecipitates with IFs during the first 30 min of the chase. Dormant, but not active (p-T567), ezrin bound in vitro to isolated denatured keratins in Far-Western analysis and to native IFs in pull-down assays. We conclude that a transient association to IFs is an early step in the polarized assembly of apical ezrin in intestinal epithelial cells.

scholarly journals STUDIES ON THE ORGANIZATION OF THE BRUSH BORDER IN INTESTINAL EPITHELIAL CELLS

1965 ◽  
Vol 26 (3) ◽  
pp. 687-691 ◽  
Author(s):  
Alexander Eichholz ◽  
Robert K. Crane
Keyword(s):  
Epithelial Cells ◽  
Brush Border ◽  
Intestinal Epithelial Cells ◽  
Companion Paper ◽  
Density Gradients ◽  
Intestinal Epithelial ◽  
Fibrillar Material ◽  
Brush Borders ◽  
Individual Bands ◽  
Positively Charged

Brush borders isolated from the epithelial cells of hamster jejunum have been dissociated by treatment with 1 M Tris(hydroxymethyl)aminomethane into several subfractions which can be separated by means of centrifugation on glycerol density gradients. Investigation of the chemical specificity of disrupting agents suggests that the amino group of Tris, in its positively charged state, is involved. Five individual bands or fractions have been routinely recovered from density gradients. The distribution of alkaline phosphatase and maltase activities among these fractions has been studied and the results indicate that both enzymes are predominantly associated with one fraction which has been identified in a companion paper as being composed of the membranes of the brush border microvilli. A fibrillar material of unidentified origin has also been obtained from Tris-disrupted brush borders.

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