Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UNIPROT:P01275 (glucagon)
26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hormone-sensitive lipase and cholesterol ester hydrolase of chicken adipose tissue were markedly activated by adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase (on the average, 235 to 275%; occasionally as much as 1000%). Diglyceride and monoglyceride hydrolases were also activated, but to a lesser extent (60 to 87%). The activation of all four hydrolases was inhibited by protein kinase inhibitor and reversed by the addition of exogenous protein kinase. Following activation by cAMP-dependent protein kinase, all four hydrolases were deactivated in a Mg2+-dependent reaction and then reactivated to or near initial levels on incubation with cAMP and Mg2+-ATP. The reversible deactivation is assumed to reflect activity of one or more protein phosphatases. The maximum activation obtainable for the four hydrolases decreased when the tissue had been previously exposed to glucagon, indicating that the glucagon-induced activation was probably similar to or identical with the activation demonstrated in cell-free preparations. The pH optima for the four hydrolase activities were similar (7.13 to 7.38). Although the absolute activities and relative degrees of kinase activation differed according to the particular emulsified substrates used, the results do not rule out the possibility that all four hydrolase activities are referable to a single hormone-sensitive hydrolase. Hormone-sensitive acyl hydrolases were separated from lipoprotein lipase by heparin-Sepharose affinity chromatography. Lipoprotein lipase was active against triolein, diolein, and monoolein, but not cholesterol oleate. Incubation of lipoprotein lipase with exogenous protein kinase, cAMP, and Mg2+ATP had no effect on any of the three hydrolase activities. Lipoprotein lipase was further purified to homogeneity and used to prepare antiserum in rabbits. The immunoglobin G fraction from these antisera completely inhibited lipoprotein lipase eluted from heparin-Sepharose columns. However, the hormone-sensitive hydrolase activities (not retained on heparin-Sepharose affinity chromatography) were not inhibited by anti-lipoprotein lipase immunoglobin G, and anti-lopoprotein lipase immunoglobin G did not affect the activation process in crude fractions. Thus, hormone-sensitive lipase and lipoprotein lipase, functionally distinct enzymes, have been physically resolved and immunochemically distinguished. Apparently lipoprotein lipase activity is not regulated, at least directly, by cAMP-dependent protein kinase.
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PMID:Triglyceride, diglyceride, monoglyceride, and cholesterol ester hydrolases in chicken adipose tissue activated by adenosine 3':5'-Monophosphate-dependent protein kinase. Chromatographic resolution and immunochemical differentiation from lipoprotein lipase. 0 45

High-performance liquid chromatography-purified 125I-vasoactive intestinal peptide (VIP) bound to T-47D human breast cancer cells in a specific, saturable, and reversible manner. Scatchard plots were compatible with the presence of one class of VIP receptors with high affinity (Kd = 4.5 X 10(-10) M VIP, and Bmax = 293 fmol/mg protein). The neuropeptide and its natural analogues inhibited the binding of 125I-VIP and stimulated cyclic AMP (cAMP) generation in T-47D cells 96-fold (EC50 = 7 X 10(-10) M VIP), in the following order of potency: VIP greater than helodermin greater than human peptide with N-terminal histidine and C-terminal methionine greater than human pancreatic growth hormone-releasing factor greater than human secretin. In contrast, 125I-VIP binding was not displaced by pancreatic glucagon, human oxyntomodulin, truncated glucagon-like peptide-1, glucagon-like peptide-2, the somatostatin analogue SMS 201-995, gastric inhibitory peptide, and a series of steroid hormones or peptides unrelated to VIP. VIP also increased cAMP generation in seven other human breast cancer cell lines: H4-66B, HSL 53, HSL 78, MCF 7, MDA-MB231, T-47D2, and ZR75-1. Adenylate cyclase activity rose from 72.2 +/- 14 to 1069 +/- 66 pmol cAMP/min mg protein after the addition of 10(-7) M VIP to T-47D plasma membranes. In agreement with our pharmacological results and the Scatchard analysis of the binding data, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the solubilized receptor in the T-47D membranes permitted identification of one autoradiographic band with a molecular weight of 69,000. The sensitivity of the Mr 69,000 binding site to GTP and low doses of VIP implies that in T-47D cells, this component constitutes the membrane domain involved in the functional regulation of adenylate cyclase by VIP receptors. Our results indicate a role for the VIP receptor-cAMP system in human breast cancer cells.
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PMID:Pharmacology, molecular identification and functional characteristics of vasoactive intestinal peptide receptors in human breast cancer cells. 284 44

These trials explored metabolic events associated with monensin-induced changes in milk composition. In trial 1, diets containing 0 or 33 ppm monensin sodium were fed ad libitum to separate groups of 7 mature lactating goats. In trial 2, diets containing 0 or 18 ppm monensin sodium were fed ad libitum to two groups with 5 mature (greater than 2 yr) and seven young (less than 2 yr) lactating does in each group. Blood was sampled at 1200 h and at 3 min after morning milking in both trials. Diets containing 33 ppm monensin increased serum growth hormone and plasma glucagon. Monensin (33 ppm) increased growth hormone from 13 to 60 ng/ml in samples taken 3 min after milking. Monensin (33 ppm) decreased insulin in these postmilking samples from 432 to 317 pg/ml but increased midday insulin in the samples taken between milkings from 279 to 349 pg/ml. Monensin did not affect plasma glucose or serum prolactin concentrations. Monensin fed at 18 ppm did not affect growth hormone, glucagon, adipose acetyl CoA carboxylase activity, hormone-sensitive lipase, or glucose concentrations. Young animals had higher growth hormone, glucose, and glucagon than mature does. The results indicate that effects of milk production intensity can be more important than monensin treatment on milk composition and circulating hormone concentrations.
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PMID:Effects of feeding monensin to lactating goats: acetyl coenzyme A carboxylase, hormone-sensitive lipase, plasma glucose, and circulating hormones. 288 43

In an attempt to explain the rarity of ketonuria in Indian diabetics, plasma glucose, insulin and free fatty acid (FFA) levels were measured in 35 non-obese patients with non-insulin-dependent diabetes in the young and 35 matched controls during a 100 g oral glucose tolerance test. Compared with the controls, the patients had a severe degree of hyperglycaemia, fasting hyperinsulinism, and an attenuated and delayed insulinaemic response. However, in addition to the fasting plasma FFA levels being similar in the two groups, the decrement in the FFA responses was equivalent. Thus, the hormone-sensitive lipase of the adipose tissue appeared to be sensitive to inhibition by insulin. Also, the fasting insulin:glucagon molar ratios were computed and found to be no different in the two groups. The normal fasting FFA levels, relative sensitivity to insulin of lipolysis in the adipocyte and normal insulin: glucagon molar ratios may help to explain in part the general rarity of ketosis-prone diabetes in the South African Indian population.
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PMID:A plausible explanation for the aketonuria of young Indian non-insulin-dependent diabetics. 392 67

Rat adipose tissue was homogenized in 0.154 m KCl, and the supernatant fluid, obtained after centrifugation at 15,000 g, was extracted with benzene to remove triglycerides. Most of the lipase activity in the extracted fluid was precipitated with ammonium sulfate between 15 and 40% saturation. The specific activity of the lipase in this fraction was about three times that in the benzene-extracted supernatant fluid. The specific activity of the monoglyceride esterase was increased to a lesser extent. Lipase activity in the benzene-extracted fluid and in the ammonium sulfate fraction was increased 15-45% by incubation with 0.3 mm ATP, 10 mm MgCl(2), and 0.03 mm cyclic AMP for 10 min before assay. None of these compounds alone or in combinations of two was as effective as all three together. The specific activity of the 15-40% ammonium sulfate fraction prepared from fat cells exposed to epinephrine and glucagon was greater than that from portions of the same cell pool not exposed to hormones. In addition, the already elevated lipase activity in preparations from hormone-treated cells was not enhanced by incubation with ATP, MgCl(2), and cyclic AMP. Thus, it seems probable that the lipase activity in the ammonium sulfate fractions represents, at least in part, hormone-sensitive lipase.
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PMID:Activation of hormone-sensitive lipase in extracts of adipose tissue. 432 64

Lipoprotein lipase (LPL) exists in two distinct fractions in heart and skeletal muscle: LPL in capillary beds regulates the metabolism of chylomicrons and very low-density lipoproteins on the surface of the endothelial cells; in contrast, the intracellular fraction of LPL regulates endogenous triacylglycerol (TG) stores. The name of the intracellular enzyme has been changed from LPL to type L hormone-sensitive lipase (HSL) because it is responsive to epinephrine and glucagon levels in heart. In this symposium evidence will show that epinephrine also activates type L HSL in skeletal muscle. Further justification for the name change is that plasma lipoproteins do not exist in parenchymal cells of muscle and the intracellular enzyme possesses many of the classical characteristics described for LPL. Exercise activates type L HSL in heart and skeletal muscle with a concomitant decrease in muscle TG stores. These results provide evidence that under a normal physiological condition, such as exercise, type L HSL participates in the regulation of intramuscular TG stores.
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PMID:Type L hormone-sensitive lipase hydrolyzes endogenous triacylglycerols in muscle in exercised rats. 662 26

We describe here an activable neutral cholesteryl esterase (EC 3.1.1.13) in arteries similar to the hormone-sensitive lipase of adipose tissue and adrenal cortex. Maximum enzyme activity in rabbit aorta was given by cholesteryl ester substrates dispersed as a mixed micelle with phosphatidylcholine and Na taurocholate (molar ratio 1:4:2). A quantitative assay of enzymic activity was obtained with the following component concentrations: 6.0 microM cholesteryl [1-14C]oleate, 23.7 microM phosphatidylcholine, 12.5 microM Na taurocholate, 0.04% serum albumin, and 85 mM K phosphate buffer, pH 7.0. The enzymic activity in aortic homogenates was stimulated 2-fold by addition of 5 microM glucagon or 100 microM dibutyryl cAMP. This activation was Mg-ATP dependent. Addition of 50 micrograms/ml of exogenous protein kinase could reverse the action of protein kinase inhibitor on dibutyryl cAMP activation of the neutral cholesteryl esterase. In addition to activation by cAMP-dependent protein kinase, the enzyme could be distinguished from the more active arterial lysosomal cholesteryl esterase by its pH 7.0 optimum, relative stability to preincubation at elevated temperatures, and exclusive localization in the cell cytosol. Subcellular fractionation of lipid-laden arterial foam cells revealed a significant portion of the neutral cholesteryl esterase bound to cytoplasmic cholesteryl ester-rich lipid droplets. Our results suggest that the breakdown of cytoplasmic cholesteryl ester droplets in arterial cells may be under hormonal regulation.
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PMID:Arterial neutral cholesteryl esterase. A hormone-sensitive enzyme distinct from lysosomal cholesteryl esterase. 684 93

Broiler adipocytes in culture were used to determine whether prolonged preincubation with an antilipolytic hormone, pancreatic polypeptide, enhances lipolysis by inducing desensitization of lipolysis inhibition. Preincubation of broiler adipocytes with pancreatic polypeptide resulted in a dose-response and time-dependent enhancement (P < .05) of basal and glucagon-stimulated lipolysis. Lipolysis was enhanced at 4 and 24 h but not at .5 h of pretreatment. Acute inhibition of basal lipolysis was unaffected by long-term (24 h) exposure of adipocytes to a maximally effective dose (12 nM) of pancreatic polypeptide. Thus, desensitization of lipolysis inhibition cannot explain the enhanced lipolysis from pancreatic polypeptide-treated adipocytes. However, preincubation with 12 nM pancreatic polypeptide for 24 h reduced (P < .05) pancreatic polypeptide and somatostatin inhibition of lipolysis stimulated by glucagon. Moreover, basal lipolysis and submaximal lipolysis were enhanced to a similar extent (27 vs 29 nmol/h) but to a greater (P < .05) extent (27 vs 13 nmol/h) than maximal lipolysis when adipocytes were exposed to 12 nM pancreatic polypeptide for 24 h. These results suggest that the enhanced lipolysis induced by prolonged exposure of adipocytes to pancreatic polypeptide resulted from increased activity of hormone-sensitive lipase and activators of this enzyme and not from attenuation of lipolysis inhibition.
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PMID:Enhanced lipolysis from broiler adipocytes pretreated with pancreatic polypeptide. 822 63

The activity of adipose tissue hormone-sensitive lipase in animals with hyperinsulinemia has been reported to be increased compared with that in control animals. We examined whether this results from a direct effect of insulin on the tissue and whether it is accompanied by alteration in the regulation of lipolysis. When rat epididymal fat pads are incubated in culture medium with bovine serum albumin for 2-4 h with 2 ng/ml or 50 microU/ml of insulin, hormone-sensitive lipase activity in the postmicrosomal supernatant fraction after acid precipitation and activation with ATP-Mg2+ increases significantly compared with preparations from tissues incubated with the vehicle. The specific activities of hormone-sensitive lipase in sonicates of adipocytes after primary culture with insulin at concentrations from 10 to 4000 ng/ml (250 microU to 100 mU/ml) increase in an insulin-dose-related manner. Lipolysis in response to 10(-7) M isoproterenol also increases in an insulin-dose-dependent manner. Enhancement of isoproterenol-mediated lipolysis is not attributable to a difference in the triglyceride content of the cells. Lipolysis caused by the beta-agonist could be completely blocked by the simultaneous presence of insulin in both control and insulin-treated cells reflecting normal responsiveness of both types of cells to the acute effect of insulin. Although an increase in lipolysis is seen with norepinephrine and growth hormone after insulin treatment, other lipolytic agents such as ACTH, thyrotropin, and glucagon evoke similar responses in insulin-treated and control cells. The simultaneous presence of growth hormone and insulin during the 16-h culture results in additive effects on the subsequent response of the cells to 10(-7) M isoproterenol compared with the responses of the cells cultured with each hormone alone. beta-Agonist-mediated cAMP accumulation in the presence of Ro-20.1724, a specific phosphodiesterase inhibitor, is significantly higher in cells cultured in the presence of insulin than in control cells. Forskolin (1-25 microM) increases the lipolytic responses of insulin-treated cells compared with control cells, but the maximal response of the insulin-treated cells to forskolin is lower than that to isoproterenol. We conclude that changes produced by chronic insulin treatment involve more than one site along the lipolytic cascade.
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PMID:Chronic exposure of rat fat cells to insulin enhances lipolysis and activation of partially purified hormone-sensitive lipase. 839 27

The effects of pyrazinoylguanidine (PZG) on lipolysis and intracellular cyclic AMP concentrations were investigated in isolated rat adipocytes. PZG reduced basal cyclic AMP concentrations and blocked in a concentration-dependent manner forskolin (1 mumol/l) and isoproterenol (1 mumol/l) stimulatory effects on intracellular cyclic AMP production and lipolysis. PZG's effects on hormone-sensitive lipase were investigated in the presence and absence of glucagon (1 mumol/l) or isoproterenol (1 mumol/l). PZG inhibited uncompetitively the induction of hormone-sensitive lipase by either glucagon or isoproterenol. PZG's antilipolytic effects appeared to result from downregulation of intracellular cyclic AMP concentrations. In adipose tissue, cyclic AMP controls lipolysis through hormone-sensitive lipase. PZG's downregulation of lipolysis and cyclic AMP concentrations was unaffected by adenosine deaminase or pertussis toxin, suggesting that PZG did not activate Gi, the inhibitory guanyl nucleotide regulatory protein.
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PMID:Studies on pyrazinoylguanidine. 3. Downregulation of lipolysis in isolated adipocytes. 895 58


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