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: EC:3.1.1.79 (hormone-sensitive lipase)
2,163 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Carbenoxolone slightly but significantly decreased the release of FFA from rat epididymal fat pads. The antilipolytic action of carbenoxolone was not blocked by 10(-3)M 3-isobutyl-1-methylxanthine, a potent inhibitor of phosphodiesterase. The findings suggest that carbenoxolone exerts its antilipolytic activity by acting on adenylate cyclase, thereby decreasing cyclic AMP concentrations and the activity of the hormone-sensitive lipase in adipose tissue.
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PMID:Effect of carbenoxolone on lipolysis in rat adipose tissue. 2 44

1. Lipolysis has been estimated by measuring the release of glycerol in isolated adipose tissue cells obtained from women in early prognancy, late pregnancy and 1 - 3 days post partum and from non-pregnant women. 2. Adipocytes of women at the end of pregnancy exhibited higher rates of lipolysis in response to adrenaline (1.5 - 15 muM) plus phentolamine (13 muM) than those of non-pregnant women or those in early pregnancy. 3. Lipolysis in response to adrenaline plus phentolamine in fat cells from women 1 - 3 days post partum was reduced compared to that at the end of gestation but was enhanced relative to that in the non-pregnant or early pregnant state. 4. Basal lipolysis also tended to be greatest at term. 5. Under conditions where the production of cyclic AMP was not rate limiting for the stimulation of lipolysis, that is in the presence of dibutyryl cyclic AMP (1 mM) or adrenaline (15 muM) plus phentolamine (13 muM) plus caffeine (1 mM), the release of glycerol in cells from women at term and in the puerperium was greater than that in women in the non-pregnant or early pregnant state. 6. Cell levels of cyclic AMP rose after incubation with adrenaline (6 muM) plus phentolamine or adrenaline (15 muM) plus phentolamine plus caffeine (1 mM) but were similar in all four groups of women. 7. It is concluded that the observed enhancement of lipolysis demonstrated in fat cells from women at the end of pregnancy reflects an increase in hormone-sensitive lipase activity rather than a modification of hormone receptor site sensitivity or of the rates of synthesis or breakdown of cyclic AMP. 8. This increase in adipose tissue lipolysis at the end of gestation could contribute to the reported rise in plasma nonesterified fatty acids in the final weeks of pregnancy.
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PMID:The effect of pregnancy on the control of lipolysis in fat cells isolated from human adipose tissue. 16 84

Starvation did not cause increase of hormone-sensitive lipase in rat epididymal adipose tissue. Adrenaline did not activate lipase in the fat cells, although it accelerated the release of free fatty acids from the cells. The results suggest that the mechanism of the stimulation of lipolysis by adrenaline is different from that in the cyclic AMP theory. Adrenaline-sensitive fat globules were prepared by hypotonic treatment of fat cells. Lipolysis in the fat globules was stimulated by adrenaline. It was shown that adrenaline-induced lipolysis in the fat globules was not due to activation of lipase but to initiation of a reaction between lipase and triglyceride. It is well known that calcium ions are essential for ACTH-induced lipolysis and that the hormone stimulates calcium uptake into adipose tissue. It was demonstrated that calcium ions accelerated formation of a complex between fat and lipase. The mechanism of the actions of adrenaline and ACTH are discussed on the basis of these results.
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PMID:Mechanism of actions of adrenaline and ACTH in fat mobilization. 17 4

A tri-, di-, and monoacylglycerol-hydrolyzing enzyme from rat adipose tissue has been detergent-solubilized and separated from monoacylglycerol lipase (H. Tornqvist and P. Belfrage, 1976, J. Biol. Chem. 251, 813-819) and lipoprotein lipase by use of ion-exchange chromatography, broad and narrow pH range electrofocusing and gel chromatography. The final preparation contained several different proteins. One of these, with an apparent minimum molecular weight of 86,000 by SDS-gel electrophoresis, was identified as the enzyme protein of hormone-sensitive lipase: a) the enzyme activity was reproducibly stimulated 50-100% by incubation with cyclic AMP-dependent protein kinase, cyclic AMP and ATP-Mg2+; b) the relative intensity of the Mw 86,000 protein band, and only this, closely paralleled the enzyme activity during narrow pH range electrofocusing and during subsequent gel chromatography of the electrofocusing enzyme peak fraction; c) only the Mw 86,000 protein extensively incorporated 32p from [gamma-32P]ATP after incubation with protein kinase and cyclic AMP. The pI of the enzyme was 6.7, it had the same Stokes radius on Sephadex G 200 as IgG and was 50% inactivated by 10 micron HgCl2, 20 micron PCMB, 50 micron DFP, 10 mM NaF and non-ionic detergents above their critical micellar concentration.
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PMID:Identification and some characteristics of the enzyme protein of the hormone-sensitive lipase from rat adipose tissue. 66 58

We established a cell-free system in which epinephrine and other lipolytic agents stimulated lipolysis of endogenous lipid droplets from fat cells by hormone-sensitive lipase. The endogenous lipid droplets were prepared by hypotonic treatment of fat cells and their successive washing with buffer containing 0.025% Triton X-100. In the cell-free system, propranolol inhibited lipolysis induced by various lipolytic agents such as norepinephrine, theophylline and cyclic AMP (cAMP), whereas phenoxybenzamine did not inhibit lipolysis. The binding of these lipolytic agents to endogenous lipid droplets was inhibited by propranolol, but not by phenoxybenzamine. The "propranolol-sensitive" binding of these lipolytic agents to the droplets may be involved in lipolysis. Treatment of the droplets with phospholipase C, but not phospholipase D, inhibited the propranolol-sensitive binding of these lipolytic agents to the droplets. These results suggest that the phosphate group of phospholipid in the droplets may be the site of propranolol-sensitive of binding of theophylline, and cAMP in addition to norepinephrine.
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PMID:Propranolol-sensitive binding of lipolytic agents to lipid droplets from adipocytes. 165 19

Phosphorylation site 2 on bovine hormone-sensitive lipase (HSL), which is phosphorylated in vitro by the AMP-activated protein kinase, has been found also to be phosphorylated in vitro by glycogen synthase kinase-4. Peptide mapping of HSL phosphorylated in vitro and in isolated adipocytes demonstrates that this site corresponds to the basal phosphorylation site on HSL, which is phosphorylated in intact adipocytes in the absence of lipolytic stimuli. Site 2 has been proposed to have an antilipolytic role in that phosphorylation at this site greatly reduces subsequent phosphorylation (at site 1) and activation of HSL by cyclic-AMP-dependent protein kinase. Further evidence for an antilipolytic role of site 2 has been obtained using a synthetic peptide based on the sequence around sites 1 and 2. Phosphorylation of the peptide at site 2 totally prevents the subsequent phosphorylation of site 1 and vice versa.
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PMID:Identification and role of the basal phosphorylation site on hormone-sensitive lipase. 216 6

Hormone-sensitive lipase is phosphorylated at a single site (site 2) in vitro by the AMP-activated protein kinase, without any direct effect on the activity of the enzyme. The amino acid sequence around this site has been determined. Ca2+/calmodulin-dependent protein kinase II also phosphorylates hormone-sensitive lipase predominantly at this site, whilst cyclic-GMP-dependent protein kinase phosphorylates exclusively the regulatory site (site 1) which is also phosphorylated by cyclic-AMP-dependent protein kinase. Phosphorylation of site 2 has been found to inhibit subsequent phosphorylation and activation of hormone-sensitive lipase by the cyclic-AMP-dependent and cyclic-GMP-dependent protein kinases, indicating that site-2 phosphorylation may have an antilipolytic role in vivo.
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PMID:Phosphorylation of bovine hormone-sensitive lipase by the AMP-activated protein kinase. A possible antilipolytic mechanism. 253

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

Adipocytes from trained rats release more free fatty acids in response to hormonal challenge compared to fat cells from sedentary rats. Lipolysis results from increased triglyceride hydrolysis that is catalyzed by a hormone-sensitive lipase, which, in turn, is activated by a phosphorylation mechanism involving cyclic AMP-dependent protein kinase. Cyclic AMP levels within the fat cell are regulated by beta-adrenergic receptor/adenylate cyclase interactions and cyclic AMP phosphodiesterase activity. This review focuses on cyclic AMP regulation of lipolysis in adipocytes from trained and sedentary animals. Although lipolysis is elevated in fat cells from trained rats, no differences are found in beta-adrenergic receptor number or affinity, adenylate cyclase activity, protein kinase activity, or partially purified hormone-sensitive lipase activity when compared to sedentary rats. The major lipolytic alteration induced by exercise training appears to occur at a site distal to hormonal regulation of the beta-adrenergic receptor.
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PMID:Cyclic AMP regulation of fuel metabolism during exercise: regulation of adipose tissue lipolysis during exercise. 285 68

In intact rat adipocytes hormone-sensitive lipase has been shown to be phosphorylated on serine residues in two different phosphorylation sites: a regulatory site phosphorylated by cyclic AMP-dependent protein kinase and a basal site, which does not directly affect the enzyme activity, phosphorylated by cyclic AMP-independent protein kinase(s) [(1984) Proc. Natl. Acad. Sci. USA 81, 3317-3321]. Cyclic GMP-dependent protein kinase catalyzed the phosphorylation of the same two phosphorylation sites on the isolated enzyme, at serine residues. Both sites were phosphorylated at about the same rate, with the hormone-sensitive lipase activity concomitantly enhanced.
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PMID:Phosphorylation of hormone-sensitive lipase by cyclic GMP-dependent protein kinase. 298 24


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