Hormone-stimulated lipolysis in cardiac myocytes

Type L hormone-sensitive lipase (HSL) activity was increased approx. 35% above control in cardiac myocytes incubated for 15 min with 5 nM-adrenaline. Concomitantly. adrenaline-stimulated myocytes had a lower triacylglycerol content, released more non-esterified fatty acid and had a higher intracellular concentration of cyclic AMP than did myocytes incubated without hormone. The lipase activity measured in adrenaline-stimulated and non-stimulated myocytes was stable in acetone/diethyl ether, stimulated by serum and inhibited by NaCl. These properties are consistent with the type L designation of this HSL. The finding that type L HSL is stimulated by adrenaline indicates that the enzyme that is being activated is found in the cell and not associated with an extracellular compartment of the myocardium.

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Hormonal activation of type-L hormone-sensitive lipase measured in defatted heart powders

Biochemical Journal ◽

10.1042/bj2120379 ◽

1983 ◽

Vol 212 (2) ◽

pp. 379-383 ◽

Cited By ~ 10

Author(s):

W K Palmer ◽

T A Kane

Keyword(s):

Cyclic Amp ◽

Diethyl Ether ◽

Rat Heart ◽

Hormone Sensitive Lipase ◽

Dependent Manner ◽

Ph Optimum ◽

Protamine Sulphate ◽

Hormone Sensitive ◽

The Stability ◽

Ether Treatment

Adrenaline, 3-isobutyl-1-methylxanthine (MIX) and dibutyryl cyclic AMP (Bt2 cyclic AMP) stimulated type-L hormone-sensitive lipase (HSL) activity when measurements were made on defatted rat heart powders. These lipolytic agents stimulated the activity of this enzyme in a time- and dose-dependent manner. This activation was reversible, because removal of adrenaline from the perfusate was accompanied by the return of type-L HSL activity to control levels. We have reported [Palmer, Caruso & Oscai (1981) Biochem. J. 198, 159-166] that perfusion with low levels of adrenaline, MIX or Bt2 cyclic AMP reduced type-L HSL activity below control levels when measurements were made in aqueous homogenates. However, in the present study, when activities were measured in acetone/diethyl ether heart powders, all concentrations of these agents studied stimulated enzyme activity, and at no concentration was there enzyme inhibition. These data suggest that acetone/diethyl ether treatment may remove a factor that plays a role in type-L HSL regulation. Type-L HSL activity measured in acetone/diethyl ether powders of control and stimulated rat heart exhibited properties that include alkaline pH optimum, serum requirement, activation by heparin and inhibition by high salt and protamine sulphate. These characteristics, in addition to the stability of the enzyme to treatment with organic solvents, fulfil the requirements for the type-L HSL classification.

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Relationship between type L hormone-sensitive lipase activity and endogenous triacylglycerol in the hearts of colchicine-treated rats

Biochemical Journal ◽

10.1042/bj2240793 ◽

1984 ◽

Vol 224 (3) ◽

pp. 793-798 ◽

Cited By ~ 1

Author(s):

W C Miller ◽

W K Palmer ◽

L B Oscai

Keyword(s):

Enzyme Activity ◽

Cyclic Amp ◽

Lipoprotein Lipase ◽

Lipase Activity ◽

Negative Relationship ◽

Indirect Evidence ◽

Colchicine Treatment ◽

Hormone Sensitive Lipase ◽

Control Value ◽

Hormone Sensitive

Colchicine injection was used as a tool to potentiate the increase in intracellular lipoprotein lipase (type L hormone-sensitive lipase) activity normally seen with fasting to determine if elevation of enzyme activity by this method produced a reduction in endogenous triacylglycerol (TG) in rat heart. Both fasting and fasting+colchicine treatment increased total lipoprotein lipase (LPL) activity from a control value of 80 units/g to approx. 144 units/g. The initial control value was obtained at 08:00 h after overnight feeding and the final values were obtained at 17:00 h, after 9 h of fasting. Fasting alone increased activity in both the capillary-bound LPL and type L hormone-sensitive lipase (HSL) fractions of cardiac muscle. In contrast, colchicine treatment, by blocking the export of enzyme from the cell as a result of microtubular disruption, restricted the increase in enzyme activity to the intracellular fraction of the heart. There was a highly significant (P less than 0.001) negative relationship (r = −0.73) between type L HSL activity and TG content in hearts of fasting and fasting+colchicine-treated rats. At a time when type L HSL activity was increased and TG content decreased, the cyclic AMP concentration of heart remained unchanged, ruling out the possibility that cyclic AMP might be activating any one of the identified cardiac TG lipases. These data provided indirect evidence that type L HSL is ‘seeing the intracellular TG droplet’ and that this enzyme may play a role in the regulation of myocardial lipolysis.

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Rat adipose tissue lipases: hormone-sensitive lipase activity against triglycerides compared with activity against lower glycerides

The Journal of Lipid Research ◽

10.1016/s0022-2275(20)40184-1 ◽

1964 ◽

Vol 5 (4) ◽

pp. 554-562 ◽

Cited By ~ 1

Author(s):

Ove Strand ◽

Martha Vaughan ◽

Daniel Steinberg

Keyword(s):

Adipose Tissue ◽

Lipase Activity ◽

Hormone Sensitive Lipase ◽

Hormone Sensitive ◽

Rat Adipose Tissue

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Expression of hormone-sensitive lipase and its regulation by adrenaline in skeletal muscle

Biochemical Journal ◽

10.1042/bj3400459 ◽

1999 ◽

Vol 340 (2) ◽

pp. 459-465 ◽

Cited By ~ 91

Author(s):

Jozef LANGFORT ◽

Thorkil PLOUG ◽

Jacob IHLEMANN ◽

Michele SALDO ◽

Cecilia HOLM ◽

...

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Soleus Muscle ◽

Lipase Activity ◽

Glycogen Phosphorylase ◽

Hormone Sensitive Lipase ◽

Dependent Protein Kinase ◽

Dependent Protein ◽

Hormone Sensitive ◽

Neutral Lipase

The enzymic regulation of triacylglycerol breakdown in skeletal muscle is poorly understood. Western blotting of muscle fibres isolated by collagenase treatment or after freeze-drying demonstrated the presence of immunoreactive hormone-sensitive lipase (HSL), with the concentrations in soleus and diaphragm being more than four times the concentrations in extensor digitorum longus and epitrochlearis muscles. Neutral lipase activity determined under conditions optimal for HSL varied directly with immunoreactivity. Expressed relative to triacylglycerol content, neutral lipase activity in soleus muscle was about 10 times that in epididymal adipose tissue. In incubated soleus muscle, both neutral lipase activity against triacylglycerol (but not against a diacylglycerol analogue) and glycogen phosphorylase activity increased in response to adrenaline (epinephrine). The lipase activation was completely inhibited by anti-HSL antibody and by propranolol. The effect of adrenaline could be mimicked by incubation of crude supernatant from control muscle with the catalytic subunit of cAMP-dependent protein kinase, while no effect of the kinase subunit was seen with supernatant from adrenaline-treated muscle. The results indicate that HSL is present in skeletal muscle and is stimulated by adrenaline via β-adrenergic activation of cAMP-dependent protein kinase. The concentration of HSL is higher in oxidative than in glycolytic muscle, and the enzyme is activated in parallel with glycogen phosphorylase.

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Clearing-factor lipase in adipose tissue. A possible role of adenosine 3′,5′-(cyclic)-monophosphate in the regulation of its activity

Biochemical Journal ◽

10.1042/bj1090841 ◽

1968 ◽

Vol 109 (5) ◽

pp. 841-849 ◽

Cited By ~ 70

Author(s):

D. R. Wing ◽

D S Robinson

Keyword(s):

Adipose Tissue ◽

Fatty Acid ◽

Free Fatty Acid ◽

Cyclic Amp ◽

Lipase Activity ◽

Glucose Concentration ◽

Free Fatty Acid Concentration ◽

Epididymal Fat ◽

Fat Bodies

1. The rise in clearing-factor lipase activity that occurs when epididymal fat bodies from starved rats are incubated in appropriate media in vitro is inhibited in the presence of 6-N-2′-O-dibutyryl-3′,5′-(cyclic)-AMP (1mm). 2. Inhibition occurs at a concentration of glucose in the incubation medium of 1·3mg./ml. or less, but not at a glucose concentration of 2·4mg./ml., unless caffeine (1mm), an inhibitor of 3′,5′-(cyclic)-nucleotide phosphodiesterase, is also present. Caffeine (5mm) alone inhibits the rise in clearing-factor lipase activity at a glucose concentration of 2·4mg./ml. of medium. 3. The concentration of free fatty acids in the epididymal fat bodies normally falls during incubations in vitro as the rise in clearing-factor lipase activity occurs. In the presence of 1mm-6-N-2′-O-dibutyryl-3′,5′-(cyclic)-AMP, however, either the tissue free fatty acid concentration is increased or it does not fall to the same extent. The concentration of glucose in the incubation medium is important in determining the direction and extent of the changes in tissue free fatty acid concentration that occur in the presence of 6-N-2′-O-dibutyryl-3′,5′-(cyclic)-AMP. 4. Free fatty acid concentrations in epididymal fat bodies in vivo rise as the clearing-factor lipase activity of the tissue falls during starvation. 5. The possibility that the concentration of 3′,5′-(cyclic)-AMP in adipose tissue may regulate clearing-factor lipase activity, and that the regulation may occur through effects of the nucleotide on tissue free fatty acid concentrations, is discussed.

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Fatty acid oxidation and triacylglycerol hydrolysis are enhanced after chronic leptin treatment in rats

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00303.2001 ◽

2002 ◽

Vol 282 (3) ◽

pp. E593-E600 ◽

Cited By ~ 65

Author(s):

Gregory R. Steinberg ◽

Arend Bonen ◽

David J. Dyck

Keyword(s):

Fatty Acid ◽

Citrate Synthase ◽

Uncoupling Protein ◽

Oxidative Capacity ◽

Hormone Sensitive Lipase ◽

Acid Oxidation ◽

Sprague Dawley ◽

Sprague Dawley Rats ◽

Triacylglycerol Hydrolysis ◽

Hormone Sensitive

Leptin acutely increases fatty acid (FA) oxidation and triacylglycerol (TG) hydrolysis and decreases TG esterification in oxidative rodent muscle. However, the effects of chronic leptin administration on FA metabolism in skeletal muscle have not been examined. We hypothesized that chronic leptin treatment would enhance TG hydrolysis as well as the capacity to oxidize FA in soleus (SOL) muscle. Female Sprague-Dawley rats were infused for 2 wk with leptin (LEPT; 0.5 mg · kg−1 · day−1) by use of subcutaneously implanted miniosmotic pumps. Control (AD-S) and pair-fed (PF-S) animals received saline-filled implants. Subsequently, FA metabolism was monitored for 45 min in isolated, resting, and contracting (20 tetani/min) SOL muscles by means of pulse-chase procedures. Food intake (−33 ± 2%, P < 0.01) and body mass (−12.5 ± 4%, P = 0.01) were reduced in both LEPT and PF-S animals. Leptin levels were elevated (+418 ± 7%, P < 0.001) in treated animals but reduced in PF-S animals (−73 ± 8%, P< 0.05) relative to controls. At rest, TG hydrolysis was increased in leptin-treated rats (1.8 ± 2.2, AD-S vs. 23.5 ± 8.1 nmol/g wet wt, LEPT; P < 0.001). In contracting SOL muscles, TG hydrolysis (1.5 ± 0.6, AD-S vs. 3.6 ± 1.0 μmol/g wet wt, LEPT; P = 0.02) and palmitate oxidation (18.3 ± 6.7, AD-S vs. 45.7 ± 9.9 nmol/g wet wt, LEPT; P < 0.05) were both significantly increased by leptin treatment. Chronic leptin treatment had no effect on TG esterification either at rest or during contraction. Markers of overall (citrate synthase) and FA (hydroxyacyl-CoA dehydrogenase) oxidative capacity were unchanged with leptin treatment. Protein expression of hormone-sensitive lipase (HSL) was also unaltered following leptin treatment. Thus leptin-induced increases in lipolysis are likely due to HSL activation (i.e., phosphorylation). Increased FA oxidation secondary to chronic leptin treatment is not due to an enhanced oxidative capacity and may be a result of enhanced flux into the mitochondrion (i.e., carnitine palmitoyltransferase I regulation) or electron transport uncoupling (i.e., uncoupling protein-3 expression).

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Physical Association between the Adipocyte Fatty Acid-binding Protein and Hormone-sensitive Lipase

Journal of Biological Chemistry ◽

10.1074/jbc.m410301200 ◽

2004 ◽

Vol 279 (50) ◽

pp. 52399-52405 ◽

Cited By ~ 39

Author(s):

Anne J. Smith ◽

Mark A. Sanders ◽

Brian R. Thompson ◽

Constantine Londos ◽

Fredric B. Kraemer ◽

...

Keyword(s):

Energy Transfer ◽

Fatty Acid ◽

Fluorescence Resonance Energy Transfer ◽

Fluorescent Protein ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

Hormone Sensitive Lipase ◽

Fatty Acid Binding ◽

Hormone Sensitive ◽

Fluorescence Resonance

Previousin vitrostudies have established that hormone sensitive lipase (HSL) and adipocyte fatty acid-binding protein (AFABP) form a physical complex that presumably positions the FABP to accept a product fatty acid generated during catalysis. To assess AFABP-HSL interaction within a cellular context, we have used lipocytes derived from 293 cells (C8PA cells) and examined physical association using fluorescence resonance energy transfer. Transfection of C8PA cells with cyan fluorescent protein (CFP)-HSL, yellow fluorescent protein (YFP)-adipocyte FABP, or YFP-liver FABP revealed that under basal conditions each protein was cytoplasmic. In the presence of 20 μmforskolin, CFP-HSL translocated to the triacylglycerol droplet, coincident with BODIPY-FA labeled depots. Fluorescence resonance energy transfer analysis demonstrated that CFP-HSL associated with YFP-adipocyte FABP in both basal and forskolin-treated cells. In contrast, little if any fluorescence resonance energy transfer could be detected between CFP-HSL and YFP-liver FABP. These results suggest that a pre-lipolysis complex containing at least AFABP and HSL exists and that the complex translocates to the surface of the lipid droplet.

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