Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Twenty human colon carcinoma cell lines were studied for their ability to develop some of the characteristics of the normal intestinal epithelium, e.g., epithelial polarity, presence of the actin-binding protein villin, or the occurrence of an enterocytic differentiation either when cultured under standard conditions, as for Caco-2 cells, or when grown in a glucose-free medium, as for HT-29 cells. Except for the regular presence of villin, which can be considered a marker of the colonic origin of the cells, the cell lines of this study could be classified into four types with regard to their differentiation characteristics. In type 1 (only one cell line, i.e., Caco-2) the cells undergo spontaneously an enterocytic differentiation characterized by a polarization of the cell layer with the formation of domes and the presence of an apical brush border the membrane of which is endowed with hydrolases such as sucrase-isomaltase, lactase, amino-peptidase N, dipeptidylpeptidase IV and alkaline phosphatase. In type 2 (three cell lines: HT-29, HCT-EB, and HCT-GEO) the cells are undifferentiated when grown in the presence of glucose but undergo an enterocytic differentiation when grown in the absence of glucose. In type 3 (eight cell lines: HCT-GLY, HCT-FET, HCT-FRI, HCT-CBS, HCT-ALA, Co-115, HRT-18, and SW-1116) the cells are organized into a polarized monolayer with the formation of domes but without any enterocytic differentiation characteristics, whatever the culture conditions. In type 4 (eight cell lines: HCT-116a, HCT-R, HCT-RCA, HCT-Moser, HCT-8R, SW-480, LS-174T, and Vaco-9P) the cells are organized into a multilayer without any feature of epithelial polarity or enterocytic differentiation, whatever the culture conditions.
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PMID:Epithelial polarity, villin expression, and enterocytic differentiation of cultured human colon carcinoma cells: a survey of twenty cell lines. 334 66

Enterocyte growth and differentiation occur simultaneously within the epithelium, but little is known regarding any relationship between these two processes. Four rat models of small intestinal epithelial hypo- and hyperplasia (neonatal ontogeny, fasting/refeeding, hypo-/hyperthyroidism, and bombesin treatment) were used to study the regulation of enterocyte gene expression in relation to epithelial growth state. Mucosal scrapings, as well as crypt and villus cell populations, were subjected to Northern blot analyses using radiolabeled cDNA probes corresponding to lactase, intestinal alkaline phosphatase, villin, ornithine decarboxylase (ODC), and the actin control. In all four models, the hypoplastic (atrophic) condition is characterized by high levels of lactase and low levels of the 3.0-kb intestinal alkaline phosphatase mRNA, whereas under hyperplastic conditions this pattern is reversed. The changes in intestinal alkaline phosphatase and lactase are qualitatively similar along the longitudinal axis of the intestine and are proportional to the degree of hyperplasia, as verified by ODC mRNA levels. Furthermore, the crypt-villus axis of differentiation is maintained regardless of epithelial growth state. In conclusion, the pattern of brush-border enzyme gene expression changes as a function of epithelial growth state, indicating a previously unrecognized degree of plasticity to the state of enterocyte differentiation.
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PMID:Pattern of rat intestinal brush-border enzyme gene expression changes with epithelial growth state. 765 20

Noninsulin-dependent diabetes mellitus (NIDDM) is an increasingly common disease, which brings a number of life-threatening complications. In rats with experimentally induced diabetes, there is an increase in the capacity of the intestine to absorb monosaccharides. We have examined the activity and the expression of monosaccharide transporters in the intestine of patients suffering from NIDDM. Na(+)-dependent D-glucose transport was 3.3-fold higher in brush-border membrane (BBM) vesicles isolated from duodenal biopsies of NIDDM patients compared with healthy controls. Western analysis indicated that SGLT1 and GLUT5 protein levels were also 4.3- and 4.1-fold higher in diabetic patients. This was associated with threefold increases in SGLT1 and GLUT5 mRNA measured by Northern blotting. GLUT2 mRNA levels were also increased threefold in the intestine of diabetic patients. Analysis of other BBM proteins indicated that the activity and abundance of sucrase and lactase were increased by 1.5- to 2-fold and the level of the structural proteins villin and beta-actin was enhanced 2-fold in diabetic patients compared with controls. The increase in the capacity of the intestine to absorb monosaccharides in human NIDDM is due to a combination of intestinal structural change with a specific increase in the expression of the monosaccharide transporters SGLT1, GLUT5, and GLUT2.
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PMID:Expression of monosaccharide transporters in intestine of diabetic humans. 1180 45

Enterocytes at the tips of microvilli are more sensitive to an ischemic insult than those cells residing in the crypts, an effect thought to be due to a relative lack of collateral flow. We speculated that this increased cellular sensitivity to ischemia might be an intrinsic feature of the cells related to their differentiated phenotype. To test this hypothesis, enterocyte response to ischemia was determined using both in vivo and in vitro models. For the in vivo studies, male Sprague-Dawley rats underwent laparotomy, and small intestinal ischemia was induced by clamping the superior mesenteric artery for 30 or 60 minutes, after which reperfusion was allowed for various time points up to 4 days. Injury was assessed histologically, as well as with Northern blots, probing for the enterocyte differentiation markers intestinal alkaline phosphatase and lactase, as well as the gut-epithelial marker villin. Mucosal changes consistent with ischemia/reperfusion injury were evident--that is, a rapid inflammatory response followed by progressive villus cell loss beginning at the tips and progressing to the crypts, depending on the degree of insult, with an eventual return to normal microanatomy. Intestinal alkaline phosphatase and lactase were lost immediately after ischemia and returned with reperfusion, confirming that the differentiated cells are particularly sensitive to ischemic injury. The in vitro studies employed two separate models of enterocyte differentiation: sodium butyrate-treated HT-29 cells and Caco-2 cells maintained for 7 days after confluence. In both models, undifferentiated and differentiated cells were subjected to treatment with 2-deoxyglucose and oligomycin-A (in vitro model of ischemia) and apoptosis was assessed by fluorescence-activated cell sorting analysis. Differentiation of both cell lines resulted in a significantly greater apoptotic response to ischemia compared to undifferentiated cells exposed to an identical insult. We conclude that differentiated enterocytes may be inherently more sensitive to ischemia-induced injury than their undifferentiated counterparts. These findings call into question the popularly held belief that villus tip cells are more susceptible to ischemia because of their location relative to the microvascular anatomy.
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PMID:Enterocyte response to ischemia is dependent on differentiation state. 1202 93

Epithelial cells are characterised by distinct apical and basolateral membrane domains that are separated by tight junctions. Establishment and maintenance of this polarity depend on specific gene expression and protein targeting to their correct location. Our former studies, performed with renal epithelial MDCK cells, revealed a new function for galectin-3, a member of a conserved family of lectins. There, galectin-3 is required for intracellular sorting and correct targeting of non-raft-associated glycoproteins to the apical plasma membrane. In the present study, we found transport defects of the intestinal brush border hydrolases lactase-phlorizin hydrolase (LPH) and dipeptidylpeptidase IV (DPPIV) in galectin-3-null mutant mice. We could show that, in enterocytes of wild-type mice, both glycoproteins directly interact with galectin-3 and transit through non-raft-dependent apical transport platforms. Therefore, this genetic analysis provides definitive evidence for the involvement of galectin-3 in protein intracellular trafficking in vivo. Further investigations revealed that gal3-null enterocytes also exhibit striking cytoarchitecture defects, with the presence of numerous and regular protrusions located along basolateral membranes. Moreover, beta-actin and villin, two characteristic markers of brush borders, become abnormally distributed along these atypical basolateral membranes in gal3(-/-) mice. Taken together, our results demonstrate that, in addition to a pivotal role in apical trafficking, galectin-3 also participates in epithelial morphogenesis in mouse enterocytes.
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PMID:Loss of galectin-3 impairs membrane polarisation of mouse enterocytes in vivo. 1821 59