The levels of lactase and of sucrase‐isomaltase along the rabbit small intestine are regulated both at the mRNA level and post‐translationally

Keller, Patrick; Zwicker, Elmar; Mantei, Ned; Semenza, Giorgio

doi:10.1016/0014-5793(92)81206-2

Cited by 33 publications

(24 citation statements)

References 33 publications

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“…This is also the case for the carbonic anhydrase 1 transcript, although this transcript is not expressed in the small intestine. Thus, each of these genes shows different developmental and cell-specific reg- RT mix, reverse transcription mixture the small intestine (12, [16][17][18][19][20][21][22], information is limited, particularly in humans, concerning their relative expression at different stages of development and in different parts of the intestine. It is hard to compare the results obtained in different studies on different samples by different methods.…”

Section: 94807 Villejuif Ceder France (M R]mentioning

confidence: 99%

Expression of Human Intestinal mRNA Transcripts during Development: Analysis by a Semiquantitative RNA Polymerase Chain Reaction Method

et al. 1994

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Section: 94807 Villejuif Ceder France (M R]mentioning

confidence: 99%

Expression of Human Intestinal mRNA Transcripts during Development: Analysis by a Semiquantitative RNA Polymerase Chain Reaction Method

et al. 1994

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“…These reports support a transcriptional mechanism for regulating the lactase maturational decline. However, a lack of correlation between the decline in lactase mRNA and enzyme expression also has been described in rats (5,7,8), rabbits (9), pigs (10), and humans (8), suggesting that post-transcriptional mechanisms may also play a role in the maturational activity decline.…”

mentioning

confidence: 99%

Regulation of Intestine-specific Spatiotemporal Expression by the Rat Lactase Promoter

Lee

Wang

Lin

et al. 2002

Journal of Biological Chemistry

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Lactase gene transcription is spatially restricted to the proximal and middle small intestine of the developing mouse. To identify regions of the lactase gene involved in mediating the spatiotemporal expression pattern, transgenic mice harboring 0.8-, 1.3-, and 2.0-kb fragments of the 5-flanking region cloned upstream of a firefly-luciferase reporter were generated. Transgene expression was assessed noninvasively in living mice using a sensitive low light imaging system. Two independent, 1.3-and 2.0-kb, lactase promoter-reporter transgenic lines expressed appropriate high levels of luciferase activity in the small intestine (300 -3,000 relative light units/g) with maximal expression in the middle segments. Post-weaned 30-day transgenic offspring also demonstrated an appropriate 4-fold maturational decline in luciferase expression in the small intestine. The pattern of the 2.0-kb promoter transgene mRNA abundance most closely mimicked that of the endogenous lactase gene with respect to spatiotemporal restriction. In contrast, a 0.8-kb promoter-reporter construct expressed low level luciferase activity (<25 relative light units/g) in multiple organs and throughout the gastrointestinal tract in transgenic mice. Thus, a distinct 5-region of the lactase promoter directs intestine-specific expression in the small intestine of transgenic mice, and regulatory sequences have been localized to a 1.2-kb region upstream of the lactase transcription start site. In addition, we have demonstrated that in vivo bioluminescence imaging can be utilized for assessment of intestinal expression patterns of a luciferase reporter gene driven by lactase promoter regions in transgenic mice.Intestinal lactase-phlorizin hydrolase (LPH, 1 lactase) is the absorptive enterocyte membrane glycoprotein essential for digestive hydrolysis of lactose in milk. Lactase is present predominantly along the brush-border membrane of differentiated enterocytes lining the villi of the small intestine. Expression of the lactase gene is spatially restricted along the longitudinal axis of the gut (1). The lactase gene is expressed maximally in the proximal and middle small intestine and declines significantly in the distal segments of the intestine. Lactase gene expression is also temporally restricted in the gut during intestinal maturation. Enzyme activity is maximal in the small intestine of pre-weaned mammals and declines markedly during maturation. The maturational decline in lactase activity contrasts with a maturational increase in enzymatic activity of other intestinal hydrolases essential for digestion of solid foods (for comprehensive review see Ref. 2).Although the mechanisms regulating the spatial and temporal restriction of lactase gene expression have not been fully defined, lactase spatiotemporal restriction is largely regulated at the level of gene transcription. This is suggested by colocalization of lactase protein along the longitudinal axis of the gut and lactase mRNA transcripts detected by Northern blot and in situ hybridization (1). With...

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“…RDEC-1 has been found to adhere to the brush borders of adult rabbits but not to those of baby rabbits (12,13). This finding was due to the demonstration that no SI appears to be present in the baby intestine, as mRNA of SI is expressed only in the intestines of adult rabbits (4,27). In this study, we observed that the numbers of bacteria that adhered to the individual brush borders with the same morphology differed from 0 to over 25 per brush border.…”

Section: Discussionmentioning

confidence: 36%

Escherichia coli Strain RDEC-1 AF/R1 Endogenous Fimbrial Glycoconjugate Receptor Molecules in Rabbit Small Intestine

et al. 2001

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Escherichia coli strain RDEC-1 causes a diarrheagenic infection in rabbits with AF/R1 fimbriae, which have been identified as an important colonization factor in RDEC-1 adherence leading to disease. The AF/R1-mediated RDEC-1 adherence model has been used as a model systems for E. coli diarrheal diseases. In this study, RDEC-1 adhered specifically to small intestinal brush borders, with both sialic acid and ␤-galactosyl residues apparently involved. The AF/R1-mediated adherence activity of [ 14 C]-labeled RDEC-1 was analyzed quantitatively by using 24-well plates coated with purified brush borders and purified microvilli. Two microvillus membrane proteins (130 and 140 kDa) were individually isolated, and chicken antibody raised to each protein inhibited bacterial adherence. These same two proteins, previously shown to be recognized by AF/R1, were individually digested with trypsin, and the amino acid sequences of peptides were determined by reversedphase capillary liquid chromatography-mass spectrometry tandem mass spectrometry (LC-MS). This LC-MS analysis indicated that these proteins are subunits of the rabbit sucrase-isomaltase protein (SI) complex. Guinea pig serum raised to purified rabbit SI complex inhibited bacterial adherence to microvilli. Additionally, as determined by high-performance thin-layer chromatography and autoradiography, RDEC-1 adhered selectively, via AF/R1 fimbriae, to a glycolipid tentatively identified as galactosylceramide (Gal␤1-1Cer) in the lipid extract of rabbit small intestinal brush borders. RDEC-1 adherence to Gal␤1-1Cer was partially inhibited in the presence of galactose. These combined results indicate that the endogenous receptor molecule for AF/R1 fimbriae of RDEC-1 is each individual component of the SI complex, although binding to glycolipid may be responsible for an additional adherence mechanism.Adherence of pathogenic bacteria to receptors on the surface of epithelial cells has been recognized as an important early event in colonization of bacteria (18). In many cases, the adhesion of Escherichia coli and other gram-negative bacteria takes place through the binding of bacterial fimbriae to specific receptors on the host cell surface, via adhesin-receptor interactions (1,2,7,11,13,24). The specificity, the affinity, and the concentrations of the interacting molecules and the presence of nutritional and inhibitory components will determine the degree of success of the bacterial colonization. Most bacterial receptor molecules have been reported to be glycoproteins and glycolipids (11,26,39,40).The first stage in pathogenesis of both enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC) infections is the fimbria-mediated adherence of the bacteria to intestinal brush borders, which then allows the production of disease through later stages involving additional virulence determinants (11,15,19). With EPEC, intestinal microvilli are effaced and the host cell cytoskeleton is dramatically rearranged to form pedestals on which the bacteria are intimately associated (...

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The levels of lactase and of sucrase‐isomaltase along the rabbit small intestine are regulated both at the mRNA level and post‐translationally

Cited by 33 publications

References 33 publications

Expression of Human Intestinal mRNA Transcripts during Development: Analysis by a Semiquantitative RNA Polymerase Chain Reaction Method

Expression of Human Intestinal mRNA Transcripts during Development: Analysis by a Semiquantitative RNA Polymerase Chain Reaction Method

Regulation of Intestine-specific Spatiotemporal Expression by the Rat Lactase Promoter

Escherichia coli Strain RDEC-1 AF/R1 Endogenous Fimbrial Glycoconjugate Receptor Molecules in Rabbit Small Intestine

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