Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lactase-phlorizin hydrolase (LPH) and sucrase-isomaltase (SI) are intestine-specific microvillus membrane hydrolases whose specific activities demonstrate reciprocal regulation during development but whose mechanisms of regulation have not been fully defined. To investigate transcriptional control of these two proteins, the rat LPH and SI genes were cloned, and antisense probes for preprocessed mRNAs (pre-mRNAs) were developed from intron sequence. LPH mRNA, as measured by quantitative ribonuclease (RNase) protection assays, was abundant before weaning and decreased two- to fourfold during weaning, whereas SI mRNA was first detected 14 days after birth and increased rapidly to abundant levels by age 28 days. LPH and SI pre-mRNA levels paralleled those of their respective mRNAs. LPH transcriptional rate declined during weaning, whereas that of SI increased during this time as determined by RNase protection assays of pre-mRNAs and nuclear run-on assays. In the adult rat, LPH mRNA was restricted to the jejunum and proximal ileum, whereas SI mRNA was detected throughout the small intestine, a pattern regulated by transcriptional rate as confirmed by nuclear run-on assays. Lactase and sucrase specific activities correlated well with their respective protein and mRNA concentrations in all experiments. We conclude that gene transcription plays a major role in the developmental and horizontal regulation of LPH and SI biosynthesis and that these two genes are regulated differently in rat small intestine.
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PMID:Transcriptional regulation of intestinal hydrolase biosynthesis during postnatal development in rats. 794 23

Expression of the gene encoding neurotensin (NT/N) is developmentally regulated in the adult small bowel with maximal expression noted in the distal ileum; the mechanisms responsible for this strict spatial-specific expression pattern are not known. The purpose of this study was to determine whether NT/N expression is altered by ileojejunal transposition. Rats underwent either sham operation or ileojejunal transposition and were killed 2 months after operation. The transposed (either jejunum or ileum) and sham-operated segments of gut were removed, a portion was processed for histologic examination, and the remainder was extracted for total RNA and analyzed by ribonuclease protection using a rat NT/N probe. For comparison, expression of another gut endocrine gene, peptide YY, and an enterocyte-specific gene, sucrase-isomaltase (SI), was also determined. Expression of the gut endocrine genes, NT/N and peptide YY, were minimally affected by transposition of either the jejunum or ileum. In contrast, SI expression was markedly altered in both the transposed jejunum and ileum compared with corresponding sham gut segments. Expression of the NT/N gene is minimally altered after jejunoileal transposition despite marked adaptive and morphologic changes in the transposed segments. These findings provide further support that the strict pattern of NT/N expression is "imprinted" in the gut and maintained regardless of location along the cephalocaudal gut axis.
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PMID:Effect of gut transposition on the expression of the endocrine gene neurotensin. 984 79