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

Lipoprotein lipase activity was measured at short time intervals in cardiac and skeletal muscles of normal and streptozotocin-treated diabetic rats fed ad libitum or deprived of food. In normal animals fed ad libitum, lipoprotein lipase activities of heart, diaphragm, soleus, and fast-twitch red fibers of the quadriceps muscle showed rhythmic oscillations that appeared to coincide with the nocturnal feeding habits of the animals. During the day (7 A.M. to 7 P.M.), when food consumption by the rats was greatly reduced, lipoprotein lipase activity in all muscles increased, followed by a decline to basal levels during the night. Similar oscillatory changes in lipoprotein lipase activity were observed in the muscles of diabetic rats fed ad libitum. In normal rats deprived of food, however, the oscillatory changes in muscle lipoprotein lipase activity were not abolished and persisted for at least 48 h. In diabetic rats starved during a 48-h period, the oscillatory changes in muscle lipoprotein lipase activity were markedly altered. In all animals, muscle lipoprotein lipase activities were not correlated to plasma glucagon levels.
 ...
PMID:Oscillatory changes in muscle lipoprotein lipase activity of fed and starved rats. 14 95

Lipoprotein lipase activity was studied in mesenchymal cells isolated from rat hearts and cultured for up to 8 days. The enzyme activity increased markedly between day 3 and 5 while the subsequent increase was less pronounced. Addition of hydrocortisone to complete culture medium resulted in an increase in lipoprotein lipase activity at all stages of culture. Lipoprotein lipase activity did not increase after addition of insulin to the complete culture medium. In the presence of serum-poor medium between day 3 and 6, the increase in lipoprotein lipase activity was much lower than in the presence of complete culture medium. Addition of hydrocortisone and insulin to the serum-poor medium resulted in a significant rise in lipoprotein lipase activity while less consistent effects were obtained after addition of each hormone alone. Transfer of cells to serum-poor medium between day 6 and 7 of culture caused a fall in enzyme activity. Addition of hydrocortisone alone and with insulin restored enzyme activity to control values. No effect on lipoprotein lipase was seen with estradiol, growth hormone, or glucagon when added to serum-containing medium, or serum-poor medium. These results indicate that the lipoprotein lipase of heart is controlled by glucocorticoids and that this control might require the presence of insulin for optimal expression.
 ...
PMID:Lipoprotein lipase of cultured mesenchymal rat heart cells. III. Effect of glucocorticoids and insulin on enzyme formation. 71 72

Lipoprotein lipase and hepatic lipase are members of the lipase gene family sharing a high degree of homology in their amino acid sequences and genomic organization. We have recently shown that isolated hepatocytes from neonatal rats express both enzyme activities. We show here that both enzymes are, however, differentially regulated. Our main findings are: (i) fasting induced an increase of the lipoprotein lipase activity but a decrease of the hepatic lipase activity in whole liver, being in both cases the vascular (heparin-releasable) compartment responsible for these variations. (ii) In isolated hepatocytes, secretion of lipoprotein lipase activity was increased by adrenaline, dexamethasone and glucagon but was not affected by epidermal growth factor, insulin or triiodothyronine. On the contrary, secretion of hepatic lipase activity was decreased by adrenaline but was not affected by other hormones. (iii) The effect of adrenaline on lipoprotein lipase activity appeared to involve beta-adrenergic receptors, but stimulation of both beta- and alpha 1-receptors seemed to be required for the effect of this hormone on hepatic lipase activity. And (iv), increased secretion of lipoprotein lipase activity was only observed after 3 h of incubation with adrenaline and was blocked by cycloheximide. On the contrary, decreased secretion of hepatic lipase activity was already significant after 90 min of incubation and was not blocked by cycloheximide. We suggest that not only synthesis of both enzymes, but also the posttranslational processing, are under separate control in the neonatal rat liver.
 ...
PMID:Lipoprotein lipase and hepatic lipase activities are differentially regulated in isolated hepatocytes from neonatal rats. 156 12

3T3-L1 adipocytes were used to test the hypothesis that hormone-sensitive lipolysis and lipoprotein lipase activity might be regulated in a reciprocal manner. Intracellular lipolysis was stimulated by catecholamine, dibutyryl cAMP, and ACTH, but not by glucagon. The effects of epinephrine on lipolysis were blocked by the beta-antagonist propanolol but not by the alpha-antagonist phentolamine. Hormone-stimulated lipolysis was not changed by acute (45 min) or chronic (2 days) treatment of the cells with insulin whereas the latter treatment augmented lipoprotein lipase activity about fivefold. Epinephrine did not affect the lipoprotein lipase activity of insulin-stimulated cells. Withdrawal of glucose from the medium decreased lipoprotein lipase activity and the effect of epinephrine on lipolysis. Effects of lipolytic agents on activity of lipoprotein lipase were variable and concentration-dependent. Lipoprotein lipase activity was decreased only by concentrations of epinephrine greater than those inducing maximal intracellular lipolysis, and the decrease in activity occurred about 30 min after the increase in glycerol release. There seems to be no relationship between the level of activity of lipoprotein lipase and the maximal rate of hormone-stimulated lipolysis in 3T3-L1 cells. Unlike in adipose tissue and adipocytes of rats, hormone-stimulated lipolysis and lipoprotein lipase activity in murine 3T3-L1 adipocytes appear to be regulated independently.
 ...
PMID:Effect of epinephrine and other lipolytic agents on intracellular lipolysis and lipoprotein lipase activity in 3T3-L1 adipocytes. 301 31

Evidence is presented that all lipase activities present in the vascular and myocardial tissue from rat heart are regulated by product inhibition. Lipoprotein lipase activity, which plays a role in the uptake of circulating triglycerides, is determined by its reaction products, e.g. fatty acids and, predominantly, monoglycerides. Tissue acid and neutral lipase activities are regulated by product fatty acids and their coenzyme A (CoA) and carnitine ester derivatives. The order of potency is palmitoyl CoA approximately palmitoyl carnitine greater than palmitate for neutral lipase and palmitoyl carnitine greater than palmitoyl CoA palmitate for acid lipase activity. Product inhibition of extracellular and intracellular lipolytic processes warrants a close coupling between the supply of substrate fatty acids and the rate of fatty acid oxidation as determined by cardiac contractile activity. None of the lipases studied was directly affected by catabolic hormones (norepinephrine, glucagon) or their intracellular second messengers (cyclic AMP, protein kinase, Ca2+, calmodulin).
 ...
PMID:Regulation of lipases involved in the supply of substrate fatty acids for the heart. 400 68

Post-heparin lipase activities were measured in normolipemic men with complaints suggestive of symptomatic coronary artery disease. A study group, who showed diffuse atherosclerotic narrowing of the coronary vessels, assessed by a quantitative computer-assisted analysis method, had a lowered hepatic lipase in comparison with a group with normal angiograms. Lipoprotein lipase was lower in the study group but well within the normal range and not statistically different. Some related hormones (cortisol, estradiol, testosterone and glucagon) were different in the two groups while others (insulin, human growth hormone, prolactin, thyroid hormones) were not. The results are discussed in view of the proposed role of hepatic lipase in the uptake of HDL-cholesterol by the liver.
 ...
PMID:Post-heparin lipases, lipids and related hormones in men undergoing coronary arteriography to assess atherosclerosis. 635 16

The sequential changes in lipid metabolism during tumor growth were evaluated in inbred Lewis rats bearing a mammary adenocarcinoma (AC33). Serum lipids, insulin, glucagon, and liver and adipose tissue lipogenic enzymes were measured in tumor-bearing and control rats after 6, 12, 18, 24, and 32 days of tumor growth. Lipoprotein lipase (LPL) activity in heart, soleus muscle, and epididymal fat pads was also determined. On the sixth day, the activity of LPL was reduced in the adipose tissue and remained lower throughout the duration of the experiment. Serum triglycerides were elevated from the 12th day followed by an increase in free fatty acid levels from the 18th day of tumor growth. These changes were accompanied by a decrease in serum insulin levels in the tumor-bearing rats from Day 12. The presence of the tumor also decreased the activities of some of the lipogenic enzymes in liver and adipose tissue, but these changes occurred at the later time points. On the 24th day, a decrease in fat pad weights was found and characterized by a decrease in fat cell size but not in fat cell number. These results suggest that a defect in clearance, due to the decrease in the activity of adipose tissue LPL, may be responsible for the early development of hypertriglyceridemia during tumor growth. In this study, the alterations in the lipogenic enzymes and LPL cannot be attributed to reduced food intake but may be due to the direct or an indirect effect of the tumor on a hormone such as insulin.
 ...
PMID:Sequential changes in the activities of lipoprotein lipase and lipogenic enzymes during tumor growth in rats. 638 47

We have studied effects of weight reduction after gastroplasty on glucose and lipid metabolism in 15 grossly obese subjects. Their body weight decreased from 127 +/- 13 to 97 +/- 14 kg 6 months after surgery and remained essentially stable 8 months later. There was a marked improvement of lipid and carbohydrate metabolism with significant reductions in blood glucose, plasma insulin and glucagon levels, and in glucose tolerance. Lipoprotein lipase activity in adipose tissue was in the upper reference range and lipoprotein lipase activity in postheparin plasma tended to be low. Plasma triglyceride, cholesterol and low-density lipoprotein cholesterol concentrations decreased significantly, while high-density lipoprotein cholesterol levels tended to rise. Concomitantly, there was an increase in triglyceride clearance rate. Most of these changes were significantly correlated to the reduction in body weight/body fat, indicating that the metabolic improvements are due to body fat reduction as such.
 ...
PMID:Effects of weight reduction after gastroplasty on glucose and lipid metabolism. 639 Nov 38

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.
 ...
PMID:Type L hormone-sensitive lipase hydrolyzes endogenous triacylglycerols in muscle in exercised rats. 662 26


1 2 Next >>