Action de la biosynthèse de l'amylase et de quelques autres enzymes du pancréas de rat

Palla, Jayasree; Abdeljlil, A. Ben; Desnuelle, P.

doi:10.1016/0304-4165(68)90068-8

Cited by 54 publications

(21 citation statements)

References 16 publications

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“…The changes, an increase and a decrease in the synthesis ofanionic trypsinogen and amylase, respectively, are observed in the table both immediately after the pulse and after a 90-min chase period. (7), lipase synthesis is regulated by secretin (13,29), and amylase synthesis is regulated by insulin (30)(31)(32)(33) and glucocorticoids (34). In contrast to the results observed after changes in diets, the findings shown here indicated no change in mRNA levels during 24 hr of caerulein stimulation.…”

Section: Methodscontrasting

confidence: 56%

Translational control of anionic trypsinogen and amylase synthesis in rat pancreas in response to caerulein stimulation.

Steinhilber

Poensgen

Rausch

et al. 1988

Proc. Natl. Acad. Sci. U.S.A.

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Infusion of rats with optimal doses of caerulein for up to 24 hr resulted in divergent changes in protein synthesis in the exocrine pancreas: a 3-fold increase in synthesis of anionic trypsinogen and a 75% decrease in synthesis of amylase. Lipase synthesis showed no change. Rates of total protein synthesis increased 2-fold, while DNA, RNA, and poly(A)+ mRNA concentrations were unchanged during hormonal stimulation. mRNA concentrations for anionic trypsinogen, lipase, and amylase were determined by dot blot hybridization analysis with cDNA and cRNA probes. Despite 12-fold changes in the ratio of synthesis of anionic trypsinogen to amylase at 24 hr of caerulein stimulation, changes in levels of mRNA encoding these two proteins were not observed. The slight decreases observed in amylase mRNA concentrations were found in both hormone and saline-infused animals. In vitro pulse-chase experiments after 12 hr of saline or caerulein infusion indicated that differential turnover of anionic trypsinogen and amylase did not occur during hormone stimulation. These data demonstrate that the differential regulation observed in protein synthesis that results from a single period of hormone stimulation is mediated by differential regulation of mRNA translation. The high degree of conservation observed in the 5' terminal sequences of both amylase and anionic trypsinogen mRNAs between mouse, rat, and dog suggests that sequence-specific mechanisms and secondary structure may play a role in the translational control of these two mRNAs.Regulation of gene expression has been studied to the greatest extent in prokaryotic organisms where mechanisms that regulate gene transcription predominate (1). In prokaryotes the half-lives of mRNA are measured in minutes (2). In eukaryotes, the half-lives of mRNA, which represent differentiated products of gene transcription (e.g., mRNAs encoding secretory products), are measured in hours to days (2, 3). mRNAs for pancreatic secretory proteins show half-lives of 3-6 hr (3). It is therefore likely that mechanisms that regulate rapid changes in gene expression in eukaryotic tissues (biological response in minutes to hours) occur at the translational level. However, few examples of translational control have been documented in higher animals. Recently, translational control has been demonstrated for insulin biosynthesis in response to changes in glucose concentrations in the blood circulation in the rat (4), for a 70-kDa protein during the response to heat shock in Drosophila (5), and for a group of =20 proteins during the early mitotic response in 3T3 cells (6). In the exocrine pancreas, we have reported that the synthesis of anionic but not cationic trypsinogen is regulated at the level of mRNA translation during caerulein stimulation (7-9). We now report that the divergent changes in synthesis of anionic trypsinogen and amylase during a 24-hr period of caerulein stimulation are regulated through mechanisms of translational control. MATERIALS AND METHODSHormone Infusion. Caerulein, a cholecyst...

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Section: Methodscontrasting

confidence: 56%

Translational control of anionic trypsinogen and amylase synthesis in rat pancreas in response to caerulein stimulation.

Steinhilber

Poensgen

Rausch

et al. 1988

Proc. Natl. Acad. Sci. U.S.A.

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“…This effect can be produced by treatment with a variety of diabetogenic agents, including streptozotocin, alloxan, and diazamide (S61ing and Unger 1972). The ability of insulin to restore normal levels in diabetic animals has been established for the intact amylase gene (Ben-Abdeljlil et al 1965;Palla et al 1968;Korc et al 1981;Osbom et al 1987) and for an amylase (-208/ + 19)/CAT hybrid gene (Osbom et al 1988). The use of transgenic mice enabled us to study this regulatory function of insulin, for which a cultured cell model is not available.…”

Section: Discussionmentioning

confidence: 99%

“…Elastase, trypsin, chymotrypsin, lipase, and ribonuclease are also expressed specifically in pancreas but are not affected in diabetic animals (Palla et al 1968;S61ing and Unger 1972;Korc et al 1981; L.C. Samuelson and M.H.…”

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confidence: 99%

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Regulation of amylase gene expression in diabetic mice is mediated by a cis-acting upstream element close to the pancreas-specific enhancer.

Keller¹,

Rosenberg²,

Johnson³

et al. 1990

Genes Dev.

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We localized the c/s-acting sequences that mediate the regulation of a pancreatic amylase gene, Amy-2.2, in diabetic mice. We constructed three hybrid genes containing sequences from the 5'-flanking region of the amylase gene upstream of the heterologous elastase promoter linked to the CAT structural gene. These constructs were transferred to the germ line of transgenic mice by microinjection of fertilized eggs. The amylase sequences had two effects on expression of the elastase promoter: Basal expression was increased, and expression in diabetic animals was reduced to -~2% of basal levels. A 30-bp amylase fragment was sufficient to transfer both of these regulatory functions to the elastase promoter. Sequences within this 30-bp fragment are included in the binding site for the pancreatic nuclear protein PTFI. The close association of the PTFl-binding site and the regulatory functions is consistent with a mechanism based on interference with activation by PTFI in diabetic pancreas. PTFl-binding activity is not reduced in diabetic pancreas. The data presented here demonstrate that the 5'-flanking region of the pancreatic amylase gene contains a novel insulin-dependent element (IDE) that mediates the loss of expression in diabetic animals.

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“…The induction of pancreatic amylase in diabetic rodents is one of the well-characterized responses to insulin (8,9). Amylase transcripts account for 20% of total mRNA in the normal pancreas.…”

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confidence: 99%

Vanadate Induction of Pancreatic Amylase mRNA in Diabetic Rats

1990

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Amylase activity and mRNA abundance are reduced to < 1 % of normal levels in diabetic rat pancreas. Administration of vanadate in drinking water restored normal amylase activity and amylase mRNA levels. These results demonstrate an effect of vanadate on pancreatic acinar cells and suggest that vanadate can mimic the effect of insulin on transcription of the pancreatic amylase gene. Diabetes 39:757-59,1990 I norganic vanadate has the remarkable property of reproducing several of the biological effects of insulin in cultured cells and intact animals (for review, see refs. 1 -3). In diabetic rats, oral administration of vanadate results in normalized blood glucose levels (1,4). The correction of hyperglycemia is accompanied by vanadate-stimulated glucose uptake in muscle and liver (5). In the liver of diabetic rats, vanadate mimics the effect of insulin on levels of glucokinase and fructose-2,6-bisphosphate activity (6,7). Molecular characterization of the insulinlike activities of vanadate is the subject of active investigation in several laboratories.The induction of pancreatic amylase in diabetic rodents is one of the well-characterized responses to insulin (8,9). Amylase transcripts account for 20% of total mRNA in the normal pancreas. When animals are given streptozocin or other diabetogenic agents, the abundance of the amylase mRNA is reduced to < 1 % of normal (10-12). Normal levels of amylase mRNA can be restored by administration of insulin. The response to insulin is dependent on an enhancer element in the 5'-flanking region of the amylase gene (13; unpublished observations). is one of the largest effects of insulin on a specific mRNA (14). In this study, we investigate the ability of vanadate to replace insulin in the regulation of pancreatic amylase. RESEARCH DESIGN AND METHODSDiabetes was induced in male Wistar rats weighing 325-340 g by injection of freshly prepared streptozocin in citrate buffer, pH 4.5, at a dose of 60 mg/kg body wt i.p. Blood glucose levels were determined 48 h after streptozocin administration with an Accu-Check II blood glucose monitor. Animals with blood glucose concentrations >17 mM were included in the study. Untreated controls were matched for age and weight.Sodium orthovanadate (0.8 mg/ml) was administered in drinking water. Treatment was initiated 7 days after administration of streptozocin and continued for 26 days. Blood glucose levels were determined at 4-day intervals. Animals that responded to vanadate with reduction of blood glucose concentrations to <11 mM were included in the study. Animals were weighed daily, and weight loss of >15 g was treated by injection of 10 ml lactated Ringer's bicarbonate solution s.c. (0.84%). Rehydration was required by -2 0 % of the rats, usually during the 1st wk of vanadate treatment.Amylase activity of pancreatic homogenates was assayed by measurement of reducing groups generated from soluble potato starch as previously described (15). One unit of amylase catalyzes the release of 1 jxmol reducing groups/min at 30°C in the presence of ...

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Action de la biosynthèse de l'amylase et de quelques autres enzymes du pancréas de rat

Cited by 54 publications

References 16 publications

Translational control of anionic trypsinogen and amylase synthesis in rat pancreas in response to caerulein stimulation.

Translational control of anionic trypsinogen and amylase synthesis in rat pancreas in response to caerulein stimulation.

Regulation of amylase gene expression in diabetic mice is mediated by a cis-acting upstream element close to the pancreas-specific enhancer.

Vanadate Induction of Pancreatic Amylase mRNA in Diabetic Rats

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