Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The role of insulin in the regulatory mechanisms governing cessation of intestinal absorption of macromolecules and sucrase development was studied in the adrenalectomized suckling rat (ADX rat). 2. Intestinal absorption of bovine immunoglobulin (IgG) infused orally was dose-dependently suppressed to 35-75% in ADX rats repeatedly injected subcutaneously with insulin. 3. When insulin was administered orally, the IgG absorption was also suppressed. 4. Intestinal sucrase activity was also induced precociously by insulin administered subcutaneously and orally. 5. These results suggest that insulin plays a role in the maturation of suppression mechanisms for macromolecular transmission and sucrase development in the small intestine of the suckling rat.
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PMID:Precocious cessation of intestinal macromolecular transmission and sucrase development induced by insulin in adrenalectomized suckling rat. 167 30

Adaptive growth and precocious expression of sucrase activity occur in the small intestine of artificially reared (AR) rat pups fed a hormone-free diet. The physiological mechanisms underlying adaptive intestinal growth were studied. Day 12 rat pups that received jejunal isografts subcutaneously on day 0 were subjected to artificial feeding and were killed on day 16. Crypt cellularity and DNA labeling index in isografts from AR, but not from mother-fed, rats increased significantly to levels found in in situ host jejunum of AR rats, indicating that humoral regulatory mechanisms are responsible for intestinal cell proliferation in AR pups. Radioimmunoassays of serum corticosterone, thyroxine, insulin, and gastrin and of gastric gastrin contents revealed that only serum corticosterone concentrations were significantly elevated, suggesting that corticosterone plays a critical role for intestinal growth. To examine this possibility directly, day 12 rats were adrenalectomized (ADX) and AR by continuous infusion of diets containing 0, 10, or 50 micrograms/ml corticosterone. Serum corticosterone concentrations paralleled the infused doses of corticosterone. Jejunal DNA labeling index increased in all ADX AR rats at day 13 in a dose-dependent manner. Increased jejunal DNA labeling index was maintained on day 14 in intact AR rats and ADX AR rats fed 10 micrograms/ml corticosterone but not in ADX AR rats receiving 0 or 50 micrograms/ml. We conclude that endogenous corticosterone is one of the systemic factors responsible for the adaptive increase in intestinal growth of AR rats.
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PMID:Hormonal regulation of adaptive intestinal growth in artificially reared rat pups. 332 40

Jejunal sucrase is known to display glucocorticoid responsiveness from birth through day 17 but not beyond that age. The aim of the current study was to determine whether this abrupt loss of responsiveness was shared by maltase, lactase, and acid beta-galactosidase. Glucocorticoid concentrations were manipulated by both adrenalectomy (ADX) and by administration of cortisone acetate (CA). Surgery or treatment was performed on each day from 16--22 days of age. Maltase activity was reduced by ADX at day 18 and earlier and was increased by CA at days 16 and 17. There were no effects at later ages. Acid beta-galactosidase was increased by ADX only at day 18 and earlier and was decreased by CA only at day 16. Lactase activity was increased by ADX at all ages up to and including day 20 but was reduced by CA only at days 16 and 17. Thus, we conclude that loss of glucocorticoid responsiveness at a relatively early stage of development is a common feature of both brush-border and lysosomal enzymes of the small intestine.
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PMID:Coordinate loss of glucocorticoid responsiveness by intestinal enzymes during postnatal development. 680 95

A yeast strain deficient in secreted invertase but expressing a cytoplasmic sucrose synthase has been used to select for potato genes that enable growth on sucrose as the sole carbon source by suppressing the sucrose uptake deficiency. Besides the already known sucrose transporter gene (StSUT1), ten different suppressor clones were identified and characterized. One of these cDNAs (PCP1) enabled efficient growth of the mutant yeast strain and mediated uptake of radiolabeled sucrose. The cDNA encodes a protein of 509 amino acids which is highly hydrophilic and thus does not seem to represent a transporter. Sequence comparisons show that the protein contains zinc finger motifs and shares weak homologies with the Drosophila couch potato gene, which serves as a transcriptional regulator, indicating that PCP1 activates a silent endogenous sucrose uptake system. The other suppressor clones encode either putative transcriptional regulators, protein kinases or enzymes involved in thiamine biosynthesis, ferredoxin reduction or glutamyl tRNA reduction and suppress the phenotype by unknown mechanisms.
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PMID:A novel zinc finger protein encoded by a couch potato homologue from Solanum tuberosum enables a sucrose transport-deficient yeast strain to grow on sucrose. 761 68

The goal of our study was to determine how sucrase-isomaltase (SI) gene expression in the rat small intestine is modulated by glucocorticoids during the second and third postnatal weeks. SI mRNA was quantitated by Northern blot and was compared with sucrase activities in the same tissue samples. The role of endogenous glucocorticoids was assessed by measuring SI mRNA and enzyme activity in rat pups adrenalectomized (ADX) on postnatal day 9. ADX pups showed a retarded appearance of sucrase activity compared with sham-operated control pups, and the appearance of SI mRNA paralleled the enzyme activity. To determine the role of exogenous glucocorticoids, a saturating dose of dexamethasone (Dex) was administered daily in three series of experiments starting on days 10, 16, and 18. In the day 10 series, Dex caused precocious appearance of both SI mRNA and sucrase activity. In the day 16 series, Dex accelerated the rate of rise of the two parameters, whereas by day 18 there was no significant effect of Dex. To investigate whether the accelerated rise in the day 16 series was associated with changes in epithelial cell kinetics, the location of SI protein was assessed by immunofluorescence staining. The results indicated that the effect of Dex at this age was due to faster emergence of SI-bearing enterocytes from the intestinal crypts.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ontogeny of sucrase-isomaltase gene expression in rat intestine: responsiveness to glucocorticoids. 844 13

The effect of hydrocortisone, sucrose, and epidermal growth factor (EGF), alone or in combination, was investigated on the precocious expression of sucrase activity and sucrase-isomaltase (SI) mRNA in normal and adrenalectomized (ADX) suckling rats. In normal rats, each regulatory factor administered separately from 12 to 13 days of age induced a parallel expression of sucrase activity and SI mRNA. A potentiation of both sucrase activity and SI mRNA was observed after administration of hydrocortisone plus sucrose. Only SI mRNA was potentiated after EGF-sucrose administration or EGF-hydrocortisone administration. However, the potentiation of the activity was obtained after a prolonged treatment period of 4 days. In adrenalectomized rats, sucrose and EGF were still able to induce precocious induction of SI mRNA and sucrase activity, but sucrase activity was lowered by 75% by sucrose and by 30% by EGF. The combined treatments gave results similar to those obtained in normal rats. The results obtained in ADX rats indicate that the effects of sucrose and EGF on the precocious expression of sucrase and the potentiation of SI mRNA are independent of endogenous glucocorticoids. The rate of [3H]thymidine incorporation into mucosal DNA of normal sucklings was similar after single or combined treatments. From this study, we conclude that the precocious induction of intestinal sucrase by various regulatory factors, alone or in combination, is primarily regulated at the level of mRNA and is independent of increases in cellular proliferation and circulating glucocorticoids.
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PMID:Sucrase-isomaltase gene expression in suckling rat intestine: hormonal, dietary, and growth factor control. 889 76