Hydrolysis of triolein, cholesterol oleate, and 4-methylumbelliferyl stearate by acid and neutral ester hydrolases (lipases) from pigeon adipose tissues: effect of cAMP-dependent protein kinase

The properties of ester hydrolases (lipases) in a pH 5.2 precipitate fraction from pigeon adipose tissue have been determined in assays which have used a variety of different substrate preparations. Hydrolase activity measured with an ethanolic triolein substrate dispersion was characterized as having a single pH optimum of 7.5. In contrast, assays performed with a glycerol-dispersed triolein preparation resulted in a distinct shoulder of hydrolase activity at acid pH values in addition to a pH optimum of 7.5; addition of lecithin to the glycerol- dispersed triolein substrate preparation decreased hydrolase activity at neutral and alkaline pH values but allowed a distinct acid pH optimum (at pH 5) to be observed. Assays with glycerol-dispersed preparations of cholesterol oleate and the fluorogenic substrate, 4-methylumbelliferyl stearate (MU-stearate) (both containing lecithin) also demonstrated hydrolase activity with both acid (pH 4.5) and neutral (pH 7.5–8) pH optima. Preincubation of the pigeon adipose tissue pH 5.2 precipitate fraction with Mg2+, ATP, and cAMP resulted in a time-dependent increase in triglyceride (TG) hydrolase activity determined at pH 7 with an ethanolic triolein emulsion. This cAMP-dependent activation could be blocked by the addition of skeletal muscle protein kinase inhibitor; the addition of exogenous protein kinase (PrK) could reverse this inhibition. A Mg2+-dependent deactivation of PrK-activated TG hydrolase was observed; the rate of deactivation was enhanced by the addition of an exogenous phosphoprotein phosphatase. A cAMP-dependent PrK-catalyzed activation of hydrolase activity measured at pH 7 could also be determined with glycerol-dispersed substrate preparations of triolein, cholesterol oleate, and MU-stearate. Acid hydrolase activity (measured at pH 4.5–5 with glycerol-dispersed substrates) was not increased by preincubation with ATP, cAMP, and PrK. In experiments with glycerol-dispersed substrates, the kinetic mechanism associated with activation of pigeon adipose tissue hydrolase(s) was found to be due to an increase in Vmax with little or no change in substrate affinity.

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AMPK Phosphorylates Desnutrin/ATGL and Hormone-Sensitive Lipase To Regulate Lipolysis and Fatty Acid Oxidation within Adipose Tissue

Molecular and Cellular Biology ◽

10.1128/mcb.00244-16 ◽

2016 ◽

Vol 36 (14) ◽

pp. 1961-1976 ◽

Cited By ~ 91

Author(s):

Sun-Joong Kim ◽

Tianyi Tang ◽

Marcia Abbott ◽

Jose A. Viscarra ◽

Yuhui Wang ◽

...

Keyword(s):

Adipose Tissue ◽

Fatty Acid ◽

Protein Kinase ◽

Hydrolase Activity ◽

Hormone Sensitive Lipase ◽

Acid Oxidation ◽

Peroxisome Proliferator ◽

Hormone Sensitive

The role of AMP-activated protein kinase (AMPK) in promoting fatty acid (FA) oxidation in various tissues, such as liver and muscle, has been well understood. However, the role of AMPK in lipolysis and FA metabolism in adipose tissue has been controversial. To investigate the role of AMPK in the regulation of adipose lipolysisin vivo, we generated mice with adipose-tissue-specific knockout of both the α1 and α2 catalytic subunits of AMPK (AMPK-ASKO mice) by using aP2-Cre and adiponectin-Cre. Both models of AMPK-ASKO ablation show no changes in desnutrin/ATGL levels but have defective phosphorylation of desnutrin/ATGL at S406 to decrease its triacylglycerol (TAG) hydrolase activity, lowering basal lipolysis in adipose tissue. These mice also show defective phosphorylation of hormone-sensitive lipase (HSL) at S565, with higher phosphorylation at protein kinase A sites S563 and S660, increasing its hydrolase activity and isoproterenol-stimulated lipolysis. With higher overall adipose lipolysis, both models of AMPK-ASKO mice are lean, having smaller adipocytes with lower TAG and higher intracellular free-FA levels. Moreover, FAs from higher lipolysis activate peroxisome proliferator-activated receptor delta to induce FA oxidative genes and increase FA oxidation and energy expenditure. Overall, for the first time, we providein vivoevidence of the role of AMPK in the phosphorylation and regulation of desnutrin/ATGL and HSL and thus adipose lipolysis.

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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.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)33473-7 ◽

1976 ◽

Vol 251 (10) ◽

pp. 2882-2890 ◽

Cited By ~ 18

Author(s):

J C Khoo ◽

D Steinberg ◽

J J Huang ◽

P R Vagelos

Keyword(s):

Adipose Tissue ◽

Protein Kinase ◽

Lipoprotein Lipase ◽

Cholesterol Ester ◽

Dependent Protein Kinase ◽

Dependent Protein ◽

Chromatographic Resolution ◽

Ester Hydrolases

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Monoacylmonoalkylglycerol as a substrate for diacylglycerol hydrolase activity in adipose tissue.

The Journal of Lipid Research ◽

10.1016/s0022-2275(20)41298-2 ◽

1978 ◽

Vol 19 (5) ◽

pp. 654-656

Author(s):

H Tornqvist ◽

P Björgell ◽

L Krabisch ◽

P Belfrage

Keyword(s):

Adipose Tissue ◽

Hydrolase Activity

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Role of the AMP-activated protein kinase in regulating fatty acid metabolism during exerciseThis paper is one of a selection of papers published in this Special Issue, entitled 14th International Biochemistry of Exercise Conference – Muscles as Molecular and Metabolic Machines, and has undergone the Journal’s usual peer review process.

Applied Physiology Nutrition and Metabolism ◽

10.1139/h09-009 ◽

2009 ◽

Vol 34 (3) ◽

pp. 315-322 ◽

Cited By ~ 26

Author(s):

Gregory R. Steinberg

Keyword(s):

Skeletal Muscle ◽

Fatty Acids ◽

Adipose Tissue ◽

Fatty Acid ◽

Protein Kinase ◽

Fatty Acid Metabolism ◽

Acid Metabolism ◽

Moderate Intensity ◽

Amp Activated Protein Kinase

During moderate-intensity exercise, fatty acids are the predominant substrate for working skeletal muscle. The release of fatty acids from adipose tissue stores, combined with the ability of skeletal muscle to actively fine tune the gradient between fatty acid and carbohydrate metabolism, depending on substrate availability and energetic demands, requires a coordinated system of metabolic control. Over the past decade, since the discovery that AMP-activated protein kinase (AMPK) was increased in accordance with exercise intensity, there has been significant interest in the proposed role of this ancient stress-sensing kinase as a critical integrative switch controlling metabolic responses during exercise. In this review, studies examining the role of AMPK as a regulator of fatty acid metabolism in both adipose tissue and skeletal muscle during exercise will be discussed. Exercise induces activation of AMPK in adipocytes and regulates triglyceride hydrolysis and esterfication through phosphorylation of hormone sensitive lipase (HSL) and glycerol-3-phosphate acyl-transferase, respectively. In skeletal muscle, exercise-induced activation of AMPK is associated with increases in fatty acid uptake, phosphorylation of HSL, and increased fatty acid oxidation, which is thought to occur via the acetyl-CoA carboxylase-malony-CoA-CPT-1 signalling axis. Despite the importance of AMPK in regulating fatty acid metabolism under resting conditions, recent evidence from transgenic models of AMPK deficiency suggest that alternative signalling pathways may also be important for the control of fatty acid metabolism during exercise.

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ATP (Mg2+) induced inhibition of cyclic AMP reactivity with a skeletal muscle protein kinase

Biochemical and Biophysical Research Communications ◽

10.1016/0006-291x(72)90542-6 ◽

1972 ◽

Vol 47 (4) ◽

pp. 653-661 ◽

Cited By ~ 58

Author(s):

Mari K. Haddox ◽

Nancy E. Newton ◽

Diane K. Hartle ◽

Nelson D. Goldberg

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Cyclic Amp ◽

Muscle Protein ◽

Skeletal Muscle Protein

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The Role of Uncoupling Protein 1 in the Metabolism and Adiposity of RIIβ-Protein Kinase A-Deficient Mice

Molecular Endocrinology ◽

10.1210/me.2004-0194 ◽

2004 ◽

Vol 18 (9) ◽

pp. 2302-2311 ◽

Cited By ~ 21

Author(s):

Michael A. Nolan ◽

Maria A. Sikorski ◽

G. Stanley McKnight

Keyword(s):

Adipose Tissue ◽

Oxygen Consumption ◽

Protein Kinase ◽

Protein Kinase A ◽

Uncoupling Protein ◽

Mrna Level ◽

Regulatory Subunit ◽

Uncoupling Protein 1 ◽

Brown Adipose ◽

Kinase A

Abstract Mice lacking the RIIβ regulatory subunit of protein kinase A exhibit a 50% reduction in white adipose tissue stores compared with wild-type littermates and are resistant to diet-induced obesity. RIIβ−/− mice also have an increase in resting oxygen consumption along with a 4-fold increase in the brown adipose-specific mitochondrial uncoupling protein 1 (UCP1). In this study, we examined the basis for UCP1 induction and tested the hypothesis that the induced levels of UCP1 in RIIβ null mice are essential for the lean phenotype. The induction of UCP1 occurred at the protein but not the mRNA level and correlated with an increase in mitochondria in brown adipose tissue. Mice lacking both RIIβ and UCP1 (RIIβ−/−/Ucp1−/−) were created, and the key parameters of metabolism and body composition were studied. We discovered that RIIβ−/− mice exhibit nocturnal hyperactivity in addition to the increased oxygen consumption at rest. Disruption of UCP1 in RIIβ−/− mice reduced basal oxygen consumption but did not prevent the nocturnal hyperactivity. The double knockout animals also retained the lean phenotype of the RIIβ null mice, demonstrating that induction of UCP1 and increased resting oxygen consumption is not the cause of leanness in the RIIβ mutant mice.

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Intravenous administration of amino acids during anesthesia stimulates muscle protein synthesis and heat accumulation in the body

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00333.2005 ◽

2006 ◽

Vol 290 (5) ◽

pp. E882-E888 ◽

Cited By ~ 24

Author(s):

Ippei Yamaoka ◽

Masako Doi ◽

Mitsuo Nakayama ◽

Akane Ozeki ◽

Shinji Mochizuki ◽

...

Keyword(s):

Protein Synthesis ◽

Protein Kinase ◽

Intravenous Administration ◽

Translation Initiation ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Mammalian Target Of Rapamycin ◽

The Body ◽

Initiation Factor ◽

Heat Accumulation

The present study was conducted to determine the contribution of muscle protein synthesis to the prevention of anesthesia-induced hypothermia by intravenous administration of an amino acid (AA) mixture. We examined the changes of intraperitoneal temperature (Tcore) and the rates of protein synthesis ( Ks) and the phosphorylation states of translation initiation regulators and their upstream signaling components in skeletal muscle in conscious (Nor) or propofol-anesthetized (Ane) rats after a 3-h intravenous administration of a balanced AA mixture or saline (Sal). Compared with Sal administration, the AA mixture administration markedly attenuated the decrease in Tcore in rats during anesthesia, whereas Tcore in the Nor-AA group became slightly elevated during treatment. Stimulation of muscle protein synthesis resulting from AA administration was observed in each case, although Ks remained lower in the Ane-AA group than in the Nor-Sal group. AA administration during anesthesia significantly increased insulin concentrations to levels ∼6-fold greater than in the Nor-AA group and enhanced phosphorylation of eukaryotic initiation factor 4E-binding protein-1 (4E-BP1) and ribosomal protein S6 protein kinase relative to all other groups and treatments. The alterations in the Ane-AA group were accompanied by hyperphosphorylation of protein kinase B and the mammalian target of rapamycin (mTOR). These results suggest that administration of an AA mixture during anesthesia stimulates muscle protein synthesis via insulin-mTOR-dependent activation of translation initiation regulators caused by markedly elevated insulin and, thereby, facilitates thermal accumulation in the body.

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