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Approaches to Measuring the Activity of Major Lipolytic and Lipogenic Enzymes In Vitro and Ex Vivo. Int J Mol Sci 2022; 23:ijms231911093. [PMID: 36232405 PMCID: PMC9570359 DOI: 10.3390/ijms231911093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/14/2022] [Accepted: 09/16/2022] [Indexed: 11/17/2022] Open
Abstract
Since the 1950s, one of the goals of adipose tissue research has been to determine lipolytic and lipogenic activity as the primary metabolic pathways affecting adipocyte health and size and thus representing potential therapeutic targets for the treatment of obesity and associated diseases. Nowadays, there is a relatively large number of methods to measure the activity of these pathways and involved enzymes, but their applicability to different biological samples is variable. Here, we review the characteristics of mean lipogenic and lipolytic enzymes, their inhibitors, and available methodologies for assessing their activity, and comment on the advantages and disadvantages of these methodologies and their applicability in vivo, ex vivo, and in vitro, i.e., in cells, organs and their respective extracts, with the emphasis on adipocytes and adipose tissue.
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Wang F, Ren X, Chen Z, Li X, Zhu H, Li S, Ou X, Zhang C, Zhang F, Zhu B. The N‐terminal His‐tag affects the triglyceride lipase activity of hormone‐sensitive lipase in testis. J Cell Biochem 2019; 120:13706-13716. [PMID: 30937958 DOI: 10.1002/jcb.28643] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/06/2019] [Accepted: 02/14/2019] [Indexed: 02/06/2023]
Affiliation(s)
- Feng Wang
- College of Life Sciences Capital Normal University Beijing China
- Fertility Preservation Lab, Reproductive Medicine Center Guangdong Second Provincial General Hospital Guangzhou China
| | - Xiao‐Fang Ren
- College of Life Sciences Capital Normal University Beijing China
| | - Zheng Chen
- College of Life Sciences Capital Normal University Beijing China
| | - Xiao‐Long Li
- Fertility Preservation Lab, Reproductive Medicine Center Guangdong Second Provincial General Hospital Guangzhou China
| | - Hai‐Jing Zhu
- Fertility Preservation Lab, Reproductive Medicine Center Guangdong Second Provincial General Hospital Guangzhou China
| | - Sen Li
- Fertility Preservation Lab, Reproductive Medicine Center Guangdong Second Provincial General Hospital Guangzhou China
| | - Xiang‐Hong Ou
- Fertility Preservation Lab, Reproductive Medicine Center Guangdong Second Provincial General Hospital Guangzhou China
| | - Cheng Zhang
- College of Life Sciences Capital Normal University Beijing China
| | - Fei‐Xiong Zhang
- College of Life Sciences Capital Normal University Beijing China
| | - Bao‐Chang Zhu
- College of Life Sciences Capital Normal University Beijing China
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Ser649 and Ser650 are the major determinants of protein kinase A-mediated activation of human hormone-sensitive lipase against lipid substrates. PLoS One 2008; 3:e3756. [PMID: 19018281 PMCID: PMC2582450 DOI: 10.1371/journal.pone.0003756] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Accepted: 10/22/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Hormone-sensitive lipase (HSL) is a key enzyme in the mobilization of fatty acids from stored triacylglycerols. Its activity is regulated by reversible protein phosphorylation. In rat HSL Ser563, Ser659 and Ser660 have been shown to be phosphorylated by protein kinase A (PKA) in vitro as well as in vivo. METHODOLOGY/PRINCIPAL FINDINGS In this study we employed site-directed mutagenesis, in vitro phosphorylation and mass spectrometry to show that in vitro phosphorylation of human HSL by PKA occurs primarily on Ser649 and Ser650 (Ser659 and Ser660 in rat HSL). The wild type enzyme and four mutants were expressed in C-terminally His-tagged form in Sf9 insect cells and purified to homogeneity. HSL variants in which Ser552 and/or Ser554 were mutated to Ala or Glu retained both lipolytic and non-lipolytic activity and were phosphorylated by PKA and activated to a similar extent as the wild type enzyme. (32)P-labeling studies revealed that the bulk of the phosphorylation was on the Ser649/Ser650 site, with only a minor phosphorylation of Ser552 and Ser554. MS/MS analysis demonstrated that the peptide containing Ser649 and Ser650 was primarily phosphorylated on Ser650. The mutant lacking all four serines had severely reduced lipolytic activity, but a lesser reduction in non-lipolytic activity, had S(0.5) values for p-nitrophenol butyrate and triolein comparable to those of wild type HSL and was not phosphorylated by PKA. PKA phosphorylation of the wild type enzyme resulted in an increase in both the maximum turnover and S(0,5) using the TO substrate. CONCLUSIONS Our results demonstrate that PKA activates human HSL against lipid substrates in vitro primarily through phosphorylation of Ser649 and Ser650. In addition the results suggest that Ser649 and Ser650 are located in the vicinity of a lipid binding region and that PKA phosphorylation controls the accessibility of this region.
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Magra AL, Mertz PS, Torday JS, Londos C. Role of adipose differentiation-related protein in lung surfactant production: a reassessment. J Lipid Res 2006; 47:2367-73. [PMID: 16936283 DOI: 10.1194/jlr.m600157-jlr200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Based on data developed with the use of isolated lipid droplets from neonatal rat lung lipofibroblasts, we speculated previously that the droplet coat protein, adipose differentiation-related protein (ADFP), mediated the transfer of lipids into type 2 lung epithelial cells for the production of surfactant phospholipids. The present studies were designed to test the role of ADFP in this transfer with the use of ADFP-coated lipid droplets from CHO fibroblast cells and a cultured human lung epithelial cell line. We found no role for ADFP in the lipid transfer and conclude that a lipase associated with the lipid droplets hydrolyzes their core triacylglycerols, releasing fatty acids that are taken up by the epithelial cells.
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Affiliation(s)
- Amy L Magra
- Membrane Regulation Section, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-8028, USA
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Su CL, Sztalryd C, Contreras JA, Holm C, Kimmel AR, Londos C. Mutational analysis of the hormone-sensitive lipase translocation reaction in adipocytes. J Biol Chem 2003; 278:43615-9. [PMID: 12832420 DOI: 10.1074/jbc.m301809200] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Lipolysis in adipocytes governs the release of fatty acids for the supply of energy to various tissues of the body. This reaction is mediated by hormone-sensitive lipase (HSL), a cytosolic enzyme, and perilipin, which coats the lipid droplet surface in adipocytes. Both HSL and perilipin are substrates for polyphosphorylation by protein kinase A (PKA), and phosphorylation of perilipin is required to induce HSL to translocate from the cytosol to the surface of the lipid droplet, a critical step in the lipolytic reaction (Sztalryd C., Xu, G., Dorward, H., Tansey, J. T., Contreras, J.A, Kimmel, A. R., and Londos, C. (2003) J. Cell Biol. 161, 1093-1103). In the present paper we demonstrate that phosphorylation at one of the two more recently discovered PKA sites within HSL, serines 659 and 660, is also required to effect the translocation reaction. Translocation does not occur when these serines residues are mutated simultaneously to alanines. Also, mutation of the catalytic Ser-423 eliminates HSL translocation, showing that the inactive enzyme does not migrate to the lipid droplet upon PKA activation. Thus, HSL translocation requires the phosphorylation of both HSL and perilipin.
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Affiliation(s)
- Chun-Li Su
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-8028, USA
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Zhang L, Wu G, Tate CG, Lookene A, Olivecrona G. Calreticulin promotes folding/dimerization of human lipoprotein lipase expressed in insect cells (sf21). J Biol Chem 2003; 278:29344-51. [PMID: 12740382 DOI: 10.1074/jbc.m300455200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipoprotein lipase (LPL) is a non-covalent, homodimeric, N-glycosylated enzyme important for metabolism of blood lipids. LPL is regulated by yet unknown post-translational events affecting the levels of active dimers. On co-expression of LPL with human molecular chaperones, we found that calreticulin had the most pronounced effects on LPL activity, but calnexin was also effective. Calreticulin caused a 9-fold increase in active LPL, amounting to about 50% of the expressed LPL protein. The total expression of LPL protein was increased less than 20%, and the secretion rates for active and inactive LPL were not significantly changed by the chaperone. Thus, the main effect was an increased specific activity of LPL both in cells and media. Chromatography on heparin-Sepharose and sucrose density gradient centrifugation demonstrated that most of the inactive LPL was monomeric and that calreticulin promoted formation of active dimers. Higher oligomers of inactive LPL were present in cell extracts, but only monomers and dimers were secreted to the medium. Interaction between LPL and calreticulin was demonstrated, and the effect of the chaperone was prevented by castanospermine, an inhibitor of N-glycan glucose trimming. Our data indicate an important role of endoplasmic reticulum-based chaperones for the folding/dimerization of LPL.
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Affiliation(s)
- Liyan Zhang
- Department of Medical Biosciences, Physiological Chemistry, Umeå University, SE-901 87 Umeå, Sweden
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Sztalryd C, Xu G, Dorward H, Tansey JT, Contreras JA, Kimmel AR, Londos C. Perilipin A is essential for the translocation of hormone-sensitive lipase during lipolytic activation. J Cell Biol 2003; 161:1093-103. [PMID: 12810697 PMCID: PMC2172984 DOI: 10.1083/jcb.200210169] [Citation(s) in RCA: 404] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Akey step in lipolytic activation of adipocytes is the translocation of hormone-sensitive lipase (HSL) from the cytosol to the surface of the lipid storage droplet. Adipocytes from perilipin-null animals have an elevated basal rate of lipolysis compared with adipocytes from wild-type mice, but fail to respond maximally to lipolytic stimuli. This defect is downstream of the beta-adrenergic receptor-adenylyl cyclase complex. Now, we show that HSL is basally associated with lipid droplet surfaces at a low level in perilipin nulls, but that stimulated translocation from the cytosol to lipid droplets is absent in adipocytes derived from embryonic fibroblasts of perilipin-null mice. We have also reconstructed the HSL translocation reaction in the nonadipocyte Chinese hamster ovary cell line by introduction of GFP-tagged HSL with and without perilipin A. On activation of protein kinase A, HSL-GFP translocates to lipid droplets only in cells that express fully phosphorylatable perilipin A, confirming that perilipin is required to elicit the HSL translocation reaction. Moreover, in Chinese hamster ovary cells that express both HSL and perilipin A, these two proteins cooperate to produce a more rapidly accelerated lipolysis than do cells that express either of these proteins alone, indicating that lipolysis is a concerted reaction mediated by both protein kinase A-phosphorylated HSL and perilipin A.
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Affiliation(s)
- Carole Sztalryd
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-2715, USA
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Osterlund T. Structure-function relationships of hormone-sensitive lipase. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:1899-907. [PMID: 11277912 DOI: 10.1046/j.1432-1327.2001.02097.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Research into the structure-function relationships of lipases and esterases has increased significantly during the past decade. Of particular importance has been the deduction of several crystal structures, providing a new basis for understanding these enzymes. The generated insights have, together with cloning and expression, aided studies on structure-function relationships of hormone-sensitive lipase (HSL). Novel phosphorylation sites have been identified in HSL, which are probably important for activation of HSL and lipolysis. Functional and structural analyses have revealed features in HSL common to lipases and esterases. In particular, the catalytic core with a catalytic triad has been unveiled. Furthermore, the investigations have given clear suggestions with regard to the identity of functional and structural domains of HSL. In the present paper, these studies on HSL structure-function relationships and short-term regulation are reviewed, and the results presented in relation to other discoveries in regulated lipolysis.
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Affiliation(s)
- T Osterlund
- Department of Biosciences at Novum, Karolinska Institute, Huddinge, Sweden.
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Holm C, Osterlund T, Laurell H, Contreras JA. Molecular mechanisms regulating hormone-sensitive lipase and lipolysis. Annu Rev Nutr 2001; 20:365-93. [PMID: 10940339 DOI: 10.1146/annurev.nutr.20.1.365] [Citation(s) in RCA: 302] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hormone-sensitive lipase, the rate-limiting enzyme of intracellular TG hydrolysis, is a major determinant of fatty acid mobilization in adipose tissue as well as other tissues. It plays a pivotal role in lipid metabolism, overall energy homeostasis, and, presumably, cellular events involving fatty acid signaling. Detailed knowledge about its structure and regulation may provide information regarding the pathogenesis of such human diseases as obesity and diabetes and may generate concepts for new treatments of these diseases. The current review summarizes the recent advances with regard to hormone-sensitive lipase structure and molecular mechanisms involved in regulating its activity and lipolysis in general. A summary of the current knowledge regarding regulation of expression, potential involvement in lipid disorders, and role in tissues other than adipose tissue is also provided.
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Affiliation(s)
- C Holm
- Department of Cell and Molecular Biology, Section for Molecular Signalling, Lund University, Lund, Sweden.
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Osterlund T, Beussman DJ, Julenius K, Poon PH, Linse S, Shabanowitz J, Hunt DF, Schotz MC, Derewenda ZS, Holm C. Domain identification of hormone-sensitive lipase by circular dichroism and fluorescence spectroscopy, limited proteolysis, and mass spectrometry. J Biol Chem 1999; 274:15382-8. [PMID: 10336425 DOI: 10.1074/jbc.274.22.15382] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Structure-function relationship analyses of hormone-sensitive lipase (HSL) have suggested that this metabolically important enzyme consists of several functional and at least two structural domains (Osterlund, T., Danielsson, B., Degerman, E., Contreras, J. A., Edgren, G., Davis, R. C., Schotz, M. C., and Holm, C. (1996) Biochem. J. 319, 411-420; Contreras, J. A., Karlsson, M., Osterlund, T., Laurell, H., Svensson, A., and Holm, C. (1996) J. Biol. Chem. 271, 31426-31430). To analyze the structural domain composition of HSL in more detail, we applied biophysical methods. Denaturation of HSL was followed by circular dichroism measurements and fluorescence spectroscopy, revealing that the unfolding of HSL is a two-step event. Using limited proteolysis in combination with mass spectrometry, several proteolytic fragments of HSL were identified, including one corresponding exactly to the proposed N-terminal domain. Major cleavage sites were found in the predicted hinge region between the two domains and in the regulatory module of the C-terminal, catalytic domain. Analyses of a hinge region cleavage mutant and calculations of the hydropathic pattern of HSL further suggest that the hinge region and regulatory module are exposed parts of HSL. Together, these data support our previous hypothesis that HSL consists of two major structural domains, encoded by exons 1-4 and 5-9, respectively, of which the latter contains an exposed regulatory module outside the catalytic alpha/beta-hydrolase fold core.
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Affiliation(s)
- T Osterlund
- Department of Cell and Molecular Biology, Lund University, S-221 00 Lund, Sweden
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Contreras JA, Danielsson B, Johansson C, Osterlund T, Langin D, Holm C. Human hormone-sensitive lipase: expression and large-scale purification from a baculovirus/insect cell system. Protein Expr Purif 1998; 12:93-9. [PMID: 9473462 DOI: 10.1006/prep.1997.0821] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hormone-sensitive lipase (HSL) is a key enzyme in lipid metabolism and overall energy homeostasis in mammals. It catalyzes the rate-limiting step in the hydrolysis of triglyceride stores in the adipocytes, delivering free fatty acids for their use as energy substrates. HSL activity is under acute hormonal and neural control, mediated through reversible phosphorylation of the enzyme. Emerging data from clinical studies indicate that HSL deficiency or malfunction is associated with several pathological situations in humans. In order to perform a biochemical characterization of human HSL, and to elucidate its molecular properties, purification of homogeneous protein in large amounts is required. Here, we describe the expression and purification of a catalytically active recombinant human HSL. The process allows the purification of milligram amounts of homogeneous protein, and should provide a valuable tool for a thorough molecular characterization of the enzyme.
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Affiliation(s)
- J A Contreras
- Department of Cell and Molecular Biology, Lund University, Lund, Sweden
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Holm C, Langin D, Manganiello V, Belfrage P, Degerman E. Regulation of hormone-sensitive lipase activity in adipose tissue. Methods Enzymol 1997; 286:45-67. [PMID: 9309644 DOI: 10.1016/s0076-6879(97)86004-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- C Holm
- Department of Cell and Molecular Biology, Lund University, Sweden
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