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

1978 ◽  
Vol 19 (5) ◽  
pp. 654-656
Author(s):  
H Tornqvist ◽  
P Björgell ◽  
L Krabisch ◽  
P Belfrage
Keyword(s):  
Adipose Tissue ◽  
Hydrolase Activity

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

2016 ◽  
Vol 36 (14) ◽  
pp. 1961-1976 ◽  
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.

scholarly journals The presence of acyl-CoA hydrolase in rat brown-adipose-tissue peroxisomes

1989 ◽  
Vol 262 (1) ◽  
pp. 41-46 ◽  
Author(s):  
S E Alexson ◽  
H Osmundsen ◽  
R K Berge
Keyword(s):  
Adipose Tissue ◽  
Substrate Specificity ◽  
Brown Adipose Tissue ◽  
Cytochrome Oxidase ◽  
Gradient Centrifugation ◽  
Hydrolase Activity ◽  
Short Chain ◽  
Marker Enzyme ◽  
Brown Adipose ◽  
Coa Hydrolase

The subcellular distribution of acyl-CoA hydrolase was studied in rat brown adipose tissue, with special emphasis on possible peroxisomal localization. Subcellular fractionation by sucrose-density-gradient centrifugation, followed by measurement of short-chain (propionyl-CoA) acyl-CoA hydrolase in the presence of NADH, resulted in two peaks of activity in the gradient: one peak corresponded to the distribution of cytochrome oxidase (mitochondrial marker enzyme), and another peak of activity coincided with the peroxisomal marker enzyme catalase. The distribution of the NADH-inhibited short-chain hydrolase activity fully resembled that of cytochrome oxidase. The substrate-specificity curve of the peroxisomal acyl-CoA hydrolase activity indicated the presence of a single enzyme exhibiting a broad substrate specificity, with maximal activity towards fatty acids with chain lengths of 3-12 carbon atoms. The mitochondrial acyl-CoA hydrolase substrate specificity, in contrast, indicated the presence of at least two acyl-CoA hydrolases (of short- and medium-chain-length specificity). The peroxisomal acyl-CoA hydrolase activity was inhibited by CoA at low (microM) concentrations and by ATP at high concentrations (greater than 0.8 mM). In contrast with the mitochondrial short-chain hydrolase, the peroxisomal acyl-CoA hydrolase activity was not inhibited by NADH.

scholarly journals Simple assay for monoacylglycerol hydrolase activity of rat adipose tissue

1974 ◽  
Vol 15 (3) ◽  
pp. 291-294
Author(s):  
Hans Tornqvist ◽  
Lennart Krabisch ◽  
Per Belfrage
Keyword(s):  
Adipose Tissue ◽  
Hydrolase Activity ◽  
Rat Adipose Tissue

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

1981 ◽  
Vol 59 (6) ◽  
pp. 418-429 ◽  
Author(s):  
David L. Severson ◽  
Thea Fletcher ◽  
Gerald Groves ◽  
Brenda Hurley ◽  
Shellie Sloan
Keyword(s):  
Adipose Tissue ◽  
Protein Kinase ◽  
Muscle Protein ◽  
Hydrolase Activity ◽  
Substrate Affinity ◽  
Ph Optimum ◽  
Ph Values ◽  
Acid Ph ◽  
Precipitate Fraction ◽  
Ester Hydrolases

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.

scholarly journals An Epistatic Interaction between Pnpla2 and Lipe Reveals New Pathways of Adipose Tissue Lipolysis

Cells ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 395 ◽  
Author(s):  
Xiao Zhang ◽  
Cong Cong Zhang ◽  
Hao Yang ◽  
Krishnakant G. Soni ◽  
Shu Pei Wang ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Epistatic Interaction ◽  
Hydrolase Activity ◽  
Hormone Sensitive Lipase ◽  
Adipose Triglyceride Lipase ◽  
Monoglyceride Lipase ◽  
Genetic Deficiency ◽  
Hormone Sensitive ◽  
Adipose Tissue Lipolysis ◽  
Hydrolysis Of

White adipose tissue (WAT) lipolysis contributes to energy balance during fasting. Lipolysis can proceed by the sequential hydrolysis of triglycerides (TGs) by adipose triglyceride lipase (ATGL), then of diacylglycerols (DGs) by hormone-sensitive lipase (HSL). We showed that the combined genetic deficiency of ATGL and HSL in mouse adipose tissue produces a striking different phenotype from that of isolated ATGL deficiency, inconsistent with the linear model of lipolysis. We hypothesized that the mechanism might be functional redundancy between ATGL and HSL. To test this, the TG hydrolase activity of HSL was measured in WAT. HSL showed TG hydrolase activity. Then, to test ATGL for activity towards DGs, radiolabeled DGs were incubated with HSL-deficient lipid droplet fractions. The content of TG increased, suggesting DG-to-TG synthesis rather than DG hydrolysis. TG synthesis was abolished by a specific ATGL inhibitor, suggesting that ATGL functions as a transacylase when HSL is deficient, transferring an acyl group from one DG to another, forming a TG plus a monoglyceride (MG) that could be hydrolyzed by monoglyceride lipase. These results reveal a previously unknown physiological redundancy between ATGL and HSL, a mechanism for the epistatic interaction between Pnpla2 and Lipe. It provides an alternative lipolytic pathway, potentially important in patients with deficient lipolysis.

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