scholarly journals Biosynthesis and maturation of lactase-phlorizin hydrolase in the human small intestinal epithelial cells

1987 ◽  
Vol 241 (2) ◽  
pp. 427-434 ◽  
Author(s):  
H Y Naim ◽  
E E Sterchi ◽  
M J Lentze
Keyword(s):  
Brush Border ◽  
Intestinal Epithelial Cells ◽  
Pulse Labelling ◽  
Intestinal Epithelial ◽  
High Mannose ◽  
Small Intestinal ◽  
Single Polypeptide ◽  
Mucosal Explants ◽  
Short Time ◽  
Time Pulse

The biosynthesis and maturation of the human intestinal lactase-phlorizin hydrolase (LPH; EC 3.2.1.23-3.2.1.62) has been studied in cultured intestinal biopsies and mucosal explants. Short time pulse labelling revealed on high mannose intermediate of Mr 215,000 which was converted upon endo-beta-N-acetylglucosaminidase H (endo-H) digestion to a polypeptide of Mr 200,000. The brush border form of LPH was revealed after longer pulse periods and has Mr 160,000. It possesses mainly complex oligosaccharide chains and, owing to its partial endo-H sensitivity, at least one chain of the high mannose type. Leupeptin partially inhibited the appearance of the Mr-160,000 polypeptide. Monensin treatment of biopsies resulted in the modification of the Mr-160,000 species to the Mr-140,000 molecule, which was endo-H sensitive. Pulse-chase analysis indicated a slow post-translational processing of the high mannose precursor (Mr 215,000) to yield the mature brush-border form (Mr 160,000) of LPH. Our results further indicate that LPH is synthesized as a single polypeptide precursor which is intracellularly cleaved to yield the mature brush border of LPH. The data presented suggest that this cleavage occurs during the translocation of the molecule across the Golgi complex.

scholarly journals Peroxynitrite Uniquely Regulates Brush Border Membrane Anion/HCO3- Exchange in Rat Small Intestinal Epithelial Cells

2011 ◽  
Vol 140 (5) ◽  
pp. S-661-S-662
Author(s):  
Andrew K. Roorda ◽  
Palanikumar Manoharan ◽  
Ramesh Kekuda ◽  
Steven D. Coon ◽  
Uma Sundaram
Keyword(s):  
Epithelial Cells ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Small Intestinal

scholarly journals miRNA-30e regulates abnormal differentiation of small intestinal epithelial cells in diabetic mice by downregulating Dll4 expression

2016 ◽  
Vol 49 (1) ◽  
pp. 102-114 ◽  
Author(s):  
Ti-Dong Shan ◽  
Hui Ouyang ◽  
Tao Yu ◽  
Jie-Yao Li ◽  
Can-Ze Huang ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Diabetic Mice ◽  
Small Intestinal

scholarly journals Functional coupling of the downregulated in adenoma Cl−/base exchanger DRA and the apical Na+/H+ exchangers NHE2 and NHE3

2009 ◽  
Vol 296 (2) ◽  
pp. G202-G210 ◽  
Author(s):  
Mark W. Musch ◽  
Donna L. Arvans ◽  
Gary D. Wu ◽  
Eugene B. Chang
Keyword(s):  
Carbonic Anhydrase ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Intestinal Epithelial Cells ◽  
Functional Coupling ◽  
Intestinal Epithelial ◽  
Colon Cells ◽  
Base Exchange ◽  
Synaptotagmin I

Non-nutrient-dependent salt absorption across the brush-border membrane of intestinal epithelial cells is primarily mediated by coupled apical Na+/H+ (aNHE) and anion exchange transport, with the latter suspected of being mediated by DRA (downregulated in adenoma; SLC26A3) that is defective in congenital chloridorrhea. To investigate DRA in greater detail and determine whether DRA and NHE activities can be coupled, we measured 22Na+ and 36Cl− uptake in Caco2BBE colon cells infected with the tet-off-inducible DRA transgene. Under basal conditions, DRA activity was low in normal and infected Caco2BBE cells in the presence of tetracycline, whereas NHE activities could be easily detected. When apical NHE activity was increased by transfection or serum-induced expression of the aNHE isoforms NHE2 and NHE3, increased 36Cl− uptake was observed. Inhibition of DRA activity by niflumic acid was greater than that by DIDS as well as by the NHE inhibitor dimethylamiloride and the carbonic anhydrase inhibitor methazolamide. DRA activity was largely aNHE-dependent, whereas a component of DRA-independent aNHE uptake continued to be observed. Coupled aNHE and DRA activities were inhibited by increased cellular cAMP and calcium and were associated with synaptotagmin I-dependent, clathrin-mediated endocytosis. In summary, these data support the role of DRA in electroneutral NaCl absorption involving functional coupling of Cl−/base exchange and apical NHE.

scholarly journals Mitochondrial gene expression in small intestinal epithelial cells

1995 ◽  
Vol 308 (2) ◽  
pp. 665-671 ◽  
Author(s):  
T P Mayall ◽  
I Bjarnason ◽  
U Y Khoo ◽  
T J Peters ◽  
A J S Macpherson
Keyword(s):  
Epithelial Cells ◽  
Cytochrome Oxidase ◽  
Cytochrome B ◽  
Intestinal Epithelial Cells ◽  
Mitochondrial Gene ◽  
Cytochrome Oxidase I ◽  
Mrna Levels ◽  
Intestinal Epithelial ◽  
Mitochondrial Transcription Factor ◽  
Small Intestinal

Most mitochondrial genes are transcribed as a single large transcript from the heavy strand of mitochondrial DNA, and are subsequently processed into the proximal mitochondrial (mt) 12 S and 16 S rRNAs, and the more distal tRNAs and mRNAs. We have shown that in intestinal epithelial biopsies the steady-state levels of mt 12 S and 16 S rRNA are an order of magnitude greater than those of mt mRNAs. Fractionation of rat small intestinal epithelial cells on the basis of their maturity has shown that the greatest ratios of 12 S mt rRNA/cytochrome b mt mRNA or 12 S mt rRNA/cytochrome oxidase I mt mRNA are found in the surface mature enterocytes, with a progressive decrease towards the crypt immature enteroblasts. Cytochrome b and cytochrome oxidase I mt mRNA levels are relatively uniform along the crypt-villus axis, but fractionation experiments showed increased levels in the crypt base. The levels of human mitochondrial transcription factor A are also greater in immature crypt enteroblasts compared with mature villus enterocytes. These results show that the relative levels of mt rRNA and mRNA are distinctly regulated in intestinal epithelial cells according to the crypt-villus position and differentiation status of the cells, and that there are higher mt mRNA and mt TFA levels in the crypts, consistent with increased transcriptional activity during mitochondrial biogenesis in the immature enteroblasts.

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.

Sign in / Sign up

Export Citation Format

Share Document