Perilipin regulates the thermogenic actions of norepinephrine in brown adipose tissue

Abstract

In response to cold, norepinephrine (NE)-induced triacylglycerol hydrolysis (lipolysis) in adipocytes of brown adipose tissue (BAT) provides fatty acid substrates to mitochondria for heat generation (adaptive thermogenesis). NE-induced lipolysis is mediated by protein kinase A (PKA)-dependent phosphorylation of perilipin, a lipid droplet-associated protein that is the major regulator of lipolysis. We investigated the role of perilipin PKA phosphorylation in BAT NE-stimulated thermogenesis using a novel mouse model in which a mutant form of perilipin, lacking all six PKA phosphorylation sites, is expressed in adipocytes of perilipin knockout (Peri KO) mice. Here, we show that despite a normal mitochondrial respiratory capacity, NE-induced lipolysis is abrogated in the interscapular brown adipose tissue (IBAT) of these mice. This lipolytic constraint is accompanied by a dramatic blunting (∼70%) of the in vivo thermal response to NE. Thus, in the presence of perilipin, PKA-mediated perilipin phosphorylation is essential for NE-dependent lipolysis and full adaptive thermogenesis in BAT. In IBAT of Peri KO mice, increased basal lipolysis attributable to the absence of perilipin is sufficient to support a rapid NE-stimulated temperature increase (∼3.0°C) comparable to that in wild-type mice. This observation suggests that one or more NE-dependent mechanism downstream of perilipin phosphorylation is required to initiate and/or sustain the IBAT thermal response. In response to cold, norepinephrine (NE)-induced triacylglycerol hydrolysis (lipolysis) in adipocytes of brown adipose tissue (BAT) provides fatty acid substrates to mitochondria for heat generation (adaptive thermogenesis). NE-induced lipolysis is mediated by protein kinase A (PKA)-dependent phosphorylation of perilipin, a lipid droplet-associated protein that is the major regulator of lipolysis. We investigated the role of perilipin PKA phosphorylation in BAT NE-stimulated thermogenesis using a novel mouse model in which a mutant form of perilipin, lacking all six PKA phosphorylation sites, is expressed in adipocytes of perilipin knockout (Peri KO) mice. Here, we show that despite a normal mitochondrial respiratory capacity, NE-induced lipolysis is abrogated in the interscapular brown adipose tissue (IBAT) of these mice. This lipolytic constraint is accompanied by a dramatic blunting (∼70%) of the in vivo thermal response to NE. Thus, in the presence of perilipin, PKA-mediated perilipin phosphorylation is essential for NE-dependent lipolysis and full adaptive thermogenesis in BAT. In IBAT of Peri KO mice, increased basal lipolysis attributable to the absence of perilipin is sufficient to support a rapid NE-stimulated temperature increase (∼3.0°C) comparable to that in wild-type mice. This observation suggests that one or more NE-dependent mechanism downstream of perilipin phosphorylation is required to initiate and/or sustain the IBAT thermal response. adipose tissue triacylglycerol lipase brown adipose tissue hormone-sensitive lipase interscapular brown adipose tissue norepinephrine perilipin isoform A perilipin knockout protein kinase A triacylglycerol uncoupling protein-1 white adipose tissue wild-type Obesity has become a major health issue in Western and developing countries as a result of increased energy intake from unhealthy diets and a sedentary lifestyle corresponding to decreased energy expenditure (1.Mokdad A. Ford E. Bowman B. Dietz W. Vinicor F. Bales V. Marks J. Prevalence of obesity, diabetes, and obesity-related health-risk factors, 2001.J. Am. Med. Assoc. 2003; 289: 76-79Crossref PubMed Scopus (4483) Google Scholar). One of the key manifestations of the metabolic imbalance resulting from obesity is the increased rate of FFA storage and release by adipose tissue. Increased FFA turnover is thought to be a critical factor for the development of insulin resistance, diabetes, and obesity-associated metabolic complications (2.Roden M. Price T. Perseghin G. Petersen K. Rothman D. Cline G. Shulman G. Mechanism of free fatty acid-induced insulin resistance in humans.J. Clin. Invest. 1996; 97: 2859-2865Crossref PubMed Scopus (1216) Google Scholar). In response to catecholamine stimulation, FFAs are released from triacylglycerol (TAG) stored within lipid droplets in white adipose tissue (WAT) and brown adipose tissue (BAT). In WAT, catecholamine-stimulated lipolysis provides fatty acids as a fuel to peripheral tissues during times of energy need. In interscapular brown adipose tissue (IBAT) of human newborns and rodents, catecholamine-stimulated lipolysis provides fatty acids for heat production in response to cold exposure or overfeeding, a process called adaptive thermogenesis (3.Robidoux J. Martin T.L. Collins S. Beta-adrenergic receptors and regulation of energy expenditure: a family affair.Annu. Rev. Pharmacol. Toxicol. 2004; 44: 297-323Crossref PubMed Scopus (105) Google Scholar). More specifically, norepinephrine (NE) is the endogenous mediator of adaptive thermogenesis (4.Thomas S. Palmitier R. Thermoregulatory metabolic phenotypes of mice lacking noradrenaline and adrenaline.Nature. 1997; 287: 94-97Crossref Scopus (219) Google Scholar, 5.Bachman E. Dhillon H. Zhang C. Cinit S. Bianco A. Koblka B. Lowell B. Beta AR signaling required for diet-induced thermogenesis and obesity resistance.Science. 2002; 297: 843-845Crossref PubMed Scopus (613) Google Scholar). Increased understanding of BAT metabolism may be critical for providing new approaches to treatments for obesity and associated disorders. In adaptive thermogenesis, fatty acids activate uncoupling protein-1 (UCP1) in the mitochondria, producing heat instead of ATP as an end product of oxidative phosphorylation (6.Kozak L. Harper M-E. Mitochondrial uncoupling proteins in energy expenditure.Annu. Rev. Nutr. 2000; 20: 339-363Crossref PubMed Scopus (91) Google Scholar, 7.Nicholls D.G. Locke R.M. Thermogenic mechanisms in brown fat.Physiol. Rev. 1984; 64: 1-64Crossref PubMed Scopus (1324) Google Scholar). IBAT thermogenesis is initiated by the binding of NE (released from sympathetic nerve endings) to β-adrenergic receptors coupled to an adenylyl cyclase system (8.Cannon B. Nedergaard J. Brown adipose tissue: function and physiological significance.Physiol. Rev. 2004; 84: 277-359Crossref PubMed Scopus (4354) Google Scholar). In white adipocytes, the increase in cAMP activates cAMP dependent protein kinase A (PKA), which phosphorylates two major substrates: hormone-sensitive lipase (HSL) and perilipins (9.Belfrage P. Fredrikson G. Olsson H. Stralfors P. Hormonal regulation of adipose tissue lipolysis by reversible phosphorylation of hormone-sensitive lipase.Prog. Clin. Biol. Res. 1982; 102: 213-223PubMed Google Scholar). Perilipins are phosphoproteins located on the surface of the lipid droplet where lipolysis occurs (10.Greenberg A.S. Egan J.J. Wek S.A. Garty N.B. Blanchette-Mackie E.J. Londos C. Perilipin, a major hormonally regulated adipocyte-specific phosphoprotein associated with the periphery of lipid storage droplets.J. Biol. Chem. 1991; 266: 11341-11346Abstract Full Text PDF PubMed Google Scholar). In the basal state, perilipins prevent the action of lipases and subsequently the hydrolysis of TAG (11.Brasaemle D. Rubin B. Harten I. Gruia-Gray J. Kimmel A. Londos C. Perilipin A increases triacylglycerol storage by decreasing the rate of triacylglycerol hydrolysis.J. Biol. Chem. 2000; 275: 38486-38493Abstract Full Text Full Text PDF PubMed Scopus (358) Google Scholar, 12.Souza S. Moitoso de Vargas L. Yamamato M. Line P. Franciosa M. Moss L. Greenberg A. Overexpression of perilipin A and B blocks the ability of tumor necrosis factor to increase adipocyte lipolysis in 3T3-L1 adipocytes.J. Biol. Chem. 1998; 273: 24665-24669Abstract Full Text Full Text PDF PubMed Scopus (247) Google Scholar, 13.Souza S. Muliro K. Liscum L. Lien P. Yamamoto Y. Schaffer J. Dallal G. Wang X. Kraemer F. Obin M. et al.Modulation of hormone-sensitive lipase and protein kinase-A-mediated lipolysis by perilipin A in an adenoviral reconstituted system.J. Biol. Chem. 2002; 277: 8267-8272Abstract Full Text Full Text PDF PubMed Scopus (193) Google Scholar). Upon phosphorylation by PKA, perilipins function as facilitators of lipolysis, orchestrating the action of lipases such as HSL and adipose tissue triacylglycerol lipase (ATGL), a recently discovered hormonally regulated lipase proposed to attenuate basal lipolysis and to enhance catecholamine-stimulated lipolysis (14.Miyoshi H. Perfield II, J.W. Souza S.C. Shen W-J. Zhang H-H. Stancheva Z.S. Kraemer F.B. Obin M.S. Greenberg A.S. Control of adipose triglyceride lipase action by serine 517 of perilipin A globally regulates protein kinase A-stimulated lipolysis in adipocytes.J. Biol. Chem. 2007; 282: 996-1002Abstract Full Text Full Text PDF PubMed Scopus (220) Google Scholar, 15.Zimmermann R. Strauss J.G. Haemmerle G. Schoiswohl G. Birner-Gruenberger R. Riederer M. Lass A. Neuberger G. Eisenhaber F. Hermetter A. et al.Fat mobilization in adipose tissue is promoted by adipose triglyceride lipase.Science. 2004; 306: 1383-1386Crossref PubMed Scopus (1451) Google Scholar). Although perilipin's role in white adipocytes is well defined, little is known about the role of perilipin and PKA-induced phosphorylation of perilipin in brown adipocytes and the resulting effects on thermogenesis. Perilipin isoform A (Peri A) is the major isoform expressed in white and brown adipocytes and has six PKA consensus sites. Recently, we demonstrated that mutating serine residues to alanines in all six sites completely abrogates cAMP-stimulated lipolysis in several in vitro cell systems (16.Zhang H.H. Souza S.C. Muliro K.V. Kraemer F.B. Obin M.S. Greenberg A.S. Lipase-selective functional domains of perilipin A differentially regulate constitutive and protein kinase A-stimulated lipolysis.J. Biol. Chem. 2003; 278: 51535-51542Abstract Full Text Full Text PDF PubMed Scopus (107) Google Scholar, 17.Miyoshi H. Souza S.C. Zhang H.H. Strissel K.J. Christoffolete M.A. Kovsan J. Rudich A. Kraemer F.B. Bianco A.C. Obin M.S. et al.Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms.J. Biol. Chem. 2006; 281: 15837-15844Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar). Despite the existence of numerous published studies in this area of investigation (16.Zhang H.H. Souza S.C. Muliro K.V. Kraemer F.B. Obin M.S. Greenberg A.S. Lipase-selective functional domains of perilipin A differentially regulate constitutive and protein kinase A-stimulated lipolysis.J. Biol. Chem. 2003; 278: 51535-51542Abstract Full Text Full Text PDF PubMed Scopus (107) Google Scholar, 17.Miyoshi H. Souza S.C. Zhang H.H. Strissel K.J. Christoffolete M.A. Kovsan J. Rudich A. Kraemer F.B. Bianco A.C. Obin M.S. et al.Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms.J. Biol. Chem. 2006; 281: 15837-15844Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar, 18.Tansey J.T. Huml A.M. Vogt R. Davis K.E. Jones J.M. Fraser K.A. Brasaemle D.L. Kimmel A.R. Londos C. Functional studies on native and mutated forms of perilipins. A role in protein kinase A-mediated lipolysis of triacylglycerols.J. Biol. Chem. 2003; 278: 8401-8406Abstract Full Text Full Text PDF PubMed Scopus (175) Google Scholar, 19.Garcia A. Subramanian V. Sekowski A. Bhattacharyya S. Love M.W. Brasaemle D.L. The amino and carboxyl termini of perilipin A facilitate the storage of triacylglycerols.J. Biol. Chem. 2004; 279: 8409-8416Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar, 20.Subramanian V. Garcia A. Sekowski A. Brasaemle D.L. Hydrophobic sequences target and anchor perilipin A to lipid droplets.J. Lipid Res. 2004; 45: 1983-1991Abstract Full Text Full Text PDF PubMed Scopus (78) Google Scholar, 21.Subramanian V. Rothenberg A. Gomez C. Cohen A.W. Garcia A. Bhattacharyya S. Shapiro L. Dolios G. Wang R. Lisanti M.P. et al.Perilipin A mediates the reversible binding of CGI-58 to lipid droplets in 3T3-L1 adipocytes.J. Biol. Chem. 2004; 279: 42062-42071Abstract Full Text Full Text PDF PubMed Scopus (244) Google Scholar), no experiments have ever been performed to examine the role of PKA-dependent phosphorylation of Peri A in regulating TAG lipolysis and adaptive thermogenesis in BAT in vivo. In this study, we used two animal models of altered perilipin function to investigate the requirement for perilipin and its PKA-dependent phosphorylation in NE-induced BAT thermogenesis, a direct measure of adaptive thermogenesis. We generated a perilipin knockout (Peri KO) mouse and a novel mouse model in which a mutant perilipin transgene lacking all six PKA phosphorylation sites expressed in adipocytes of the Peri KO mouse (Peri H. Souza S.C. Zhang H.H. Strissel K.J. Christoffolete M.A. Kovsan J. Rudich A. Kraemer F.B. Bianco A.C. Obin M.S. et al.Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms.J. Biol. Chem. 2006; 281: 15837-15844Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar). studies that perilipin is its PKA-dependent phosphorylation is for lipolysis and normal adaptive thermogenesis in vivo. studies in Peri KO mice that adaptive thermogenesis in vivo NE-dependent mechanisms in to lipolysis. and a mouse for the from from A and a generated as S. Muliro K. Liscum L. Lien P. Yamamoto Y. Schaffer J. Dallal G. Wang X. Kraemer F. Obin M. et al.Modulation of hormone-sensitive lipase and protein kinase-A-mediated lipolysis by perilipin A in an adenoviral reconstituted system.J. Biol. Chem. 2002; 277: 8267-8272Abstract Full Text Full Text PDF PubMed Scopus (193) Google Scholar). generated using the and subsequently for in Western The from and used to the Peri KO mice generated by of the perilipin which to with a the of all known perilipin Peri KO mice for to mice We generated a mouse Peri with a the using a H. Souza S.C. Zhang H.H. Strissel K.J. Christoffolete M.A. Kovsan J. Rudich A. Kraemer F.B. Bianco A.C. Obin M.S. et al.Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms.J. Biol. Chem. 2006; 281: 15837-15844Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar). This a of the the tumor and a of B. M. V. mice the in adipose tissue are to 1997; PubMed Scopus Google Scholar). A the transgene of mice. mice the Peri transgene in IBAT mice with Peri KO mice to the Peri mice for the used in these studies H. Souza S.C. Zhang H.H. Strissel K.J. Christoffolete M.A. Kovsan J. Rudich A. Kraemer F.B. Bianco A.C. Obin M.S. et al.Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms.J. Biol. Chem. 2006; 281: 15837-15844Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar). mice with all performed and of from BAT and by by as D. and of A Scholar). with a in a system using as the in the absence and presence of are expressed as of of protein The protein of the mitochondrial using a acid IBAT and thermal response to NE as J.J. G. Bianco A.C. and adaptive thermogenesis are Clin. Invest. PubMed Scopus Google Scholar). with a of and on the of the with a the of the A the and used for NE IBAT using a the brown temperature with a The to a temperature and IBAT during a of to a by NE using an model for and expressed in of in temperature and performed on of IBAT from wild-type Peri and Peri KO mice. lipid of IBAT tissue in of and lipid in of and TAG using triglyceride TAG is expressed in of tissue and the of mice tissue proteins as S.C. Yamamoto M. Franciosa M. Lien P. Greenberg A. blocks the lipolytic of tumor necrosis a new mechanism for the 1998; PubMed Scopus Google and using the protein by to and as S. Muliro K. Liscum L. Lien P. Yamamoto Y. Schaffer J. Dallal G. Wang X. Kraemer F. Obin M. et al.Modulation of hormone-sensitive lipase and protein kinase-A-mediated lipolysis by perilipin A in an adenoviral reconstituted system.J. Biol. Chem. 2002; 277: 8267-8272Abstract Full Text Full Text PDF PubMed Scopus (193) Google Scholar). Brown adipocytes using and of IBAT as M. J.W. Bianco A.C. The is essential for adaptive thermogenesis in brown adipose Clin. Invest. PubMed Scopus Google with BAT and in and and tissue a by and using a Brown adipocytes from Peri or Peri KO mice in and lipolysis basal and rate as released the using a S. Muliro K. Liscum L. Lien P. Yamamoto Y. Schaffer J. Dallal G. Wang X. Kraemer F. Obin M. et al.Modulation of hormone-sensitive lipase and protein kinase-A-mediated lipolysis by perilipin A in an adenoviral reconstituted system.J. Biol. Chem. 2002; 277: 8267-8272Abstract Full Text Full Text PDF PubMed Scopus (193) Google Scholar). is expressed to of fatty acids using an S.C. Yamamoto M. Franciosa M. Lien P. Greenberg A. blocks the lipolytic of tumor necrosis a new mechanism for the 1998; PubMed Scopus Google Scholar). from IBAT using a lipid by and from of performed in on an in a of using using on by the critical K.J. of using and the PubMed Scopus Google and to an endogenous that are by the where is the in for the target and are as or performed using A of the adipocyte-specific the of a Peri A in all six PKA sites, used to a mouse mice with Peri KO mice, the Peri mice with adipose Peri The mice the and normal and by Peri and Peri KO mice The tissue of the transgene by Western of Peri protein Peri protein to adipose no in or of the Peri mice. Peri protein in these mice in with a in and This Peri in that in the Peri KO mice in mice IBAT from Peri mice to be more to that of mice, the in Peri KO mice Peri Peri in white adipocytes, the absence of perilipin in IBAT is associated with the of which the lipid droplets S. Muliro K. Liscum L. Lien P. Yamamoto Y. Schaffer J. Dallal G. Wang X. Kraemer F. Obin M. et al.Modulation of hormone-sensitive lipase and protein kinase-A-mediated lipolysis by perilipin A in an adenoviral reconstituted system.J. Biol. Chem. 2002; 277: 8267-8272Abstract Full Text Full Text PDF PubMed Scopus (193) Google Scholar, J. C. Gruia-Gray J. D. J. M. C. Kimmel A. Londos C. Perilipin in a mouse with adipocyte lipolysis, and resistance to diet-induced PubMed Scopus Google Scholar). The of the protein lipases HSL and Peri and Peri KO mice of IBAT from mice that IBAT of Peri mice lipid droplets and more TAG that in mice In IBAT of Peri KO mice lipid droplets and TAG that in mice. the of perilipin A or perilipin in IBAT of and Peri mice, we used the model to the in vivo role of PKA-dependent perilipin phosphorylation in adaptive thermogenesis. IBAT thermogenesis we in the temperature of the IBAT in response to a NE in mice. In mice, NE a rapid and increase in IBAT and which of and the increase in temperature a of with the IBAT thermal the temperature J.J. G. Bianco A.C. and adaptive thermogenesis are Clin. Invest. PubMed Scopus Google Scholar). the IBAT thermal in the Peri KO mice with mice, in Peri mice an are as the temperature in the Peri mice to increase a in the Peri adaptive thermogenesis. the in the Peri IBAT is to a mitochondrial we the protein in animal models by Western and to be to we IBAT of in mitochondrial and and no the of Functional mitochondrial studies performed by of IBAT mitochondria in the presence of as and in the presence of D. and of A Scholar). The no in IBAT mitochondrial during and of Peri and Peri KO mice is that no increase in the of the of IBAT mitochondria S. Zhang Lowell The mitochondrial Rev. Biol. PubMed Scopus Google Scholar). a in mitochondria from and to be comparable in Peri and Peri KO mice, as D. and of A Scholar), increased of mitochondrial A increase in and FFA release in brown adipocytes with NE for In NE-stimulated lipolysis abrogated in Peri brown adipocytes the cAMP-stimulated lipolysis in cell models of Peri (16.Zhang H.H. Souza S.C. Muliro K.V. Kraemer F.B. Obin M.S. Greenberg A.S. Lipase-selective functional domains of perilipin A differentially regulate constitutive and protein kinase A-stimulated lipolysis.J. Biol. Chem. 2003; 278: 51535-51542Abstract Full Text Full Text PDF PubMed Scopus (107) Google Scholar, 17.Miyoshi H. Souza S.C. Zhang H.H. Strissel K.J. Christoffolete M.A. Kovsan J. Rudich A. Kraemer F.B. Bianco A.C. Obin M.S. et al.Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms.J. Biol. Chem. 2006; 281: 15837-15844Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar). lipolysis the of basal of perilipin brown adipocytes of Peri KO mice an increased basal and fatty acid release rate that by exposure to NE This provides the in vivo that perilipin phosphorylation is required for normal lipolysis and adaptive thermogenesis in BAT. the role of perilipin PKA phosphorylation sites in BAT thermogenesis, we a novel model Peri which a mutant perilipin transgene lacking all six PKA phosphorylation sites in adipocytes of Peri KO mice In these mice, perilipin is expressed on the lipid droplets of brown adipocytes and the of basal lipolysis are perilipin's as a to lipases in the (11.Brasaemle D. Rubin B. Harten I. Gruia-Gray J. Kimmel A. Londos C. Perilipin A increases triacylglycerol storage by decreasing the rate of triacylglycerol hydrolysis.J. Biol. Chem. 2000; 275: 38486-38493Abstract Full Text Full Text PDF PubMed Scopus (358) Google Scholar, 13.Souza S. Muliro K. Liscum L. Lien P. Yamamoto Y. Schaffer J. Dallal G. Wang X. Kraemer F. Obin M. et al.Modulation of hormone-sensitive lipase and protein kinase-A-mediated lipolysis by perilipin A in an adenoviral reconstituted system.J. Biol. Chem. 2002; 277: 8267-8272Abstract Full Text Full Text PDF PubMed Scopus (193) Google Scholar, H. Perfield II, J.W. Souza S.C. Shen W-J. Zhang H-H. Stancheva Z.S. Kraemer F.B. Obin M.S. Greenberg A.S. Control of adipose triglyceride lipase action by serine 517 of perilipin A globally regulates protein kinase A-stimulated lipolysis in adipocytes.J. Biol. Chem. 2007; 282: 996-1002Abstract Full Text Full Text PDF PubMed Scopus (220) Google Scholar, H.H. Souza S.C. Muliro K.V. Kraemer F.B. Obin M.S. Greenberg A.S. Lipase-selective functional domains of perilipin A differentially regulate constitutive and protein kinase A-stimulated lipolysis.J. Biol. Chem. 2003; 278: 51535-51542Abstract Full Text Full Text PDF PubMed Scopus (107) Google Scholar, 17.Miyoshi H. Souza S.C. Zhang H.H. Strissel K.J. Christoffolete M.A. Kovsan J. Rudich A. Kraemer F.B. Bianco A.C. Obin M.S. et al.Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms.J. Biol. Chem. 2006; 281: 15837-15844Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar, J. C. Gruia-Gray J. D. J. M. C. Kimmel A. Londos C. Perilipin in a mouse with adipocyte lipolysis, and resistance to diet-induced PubMed Scopus Google Scholar). perilipin be by PKA, NE-induced lipolysis as well (16.Zhang H.H. Souza S.C. Muliro K.V. Kraemer F.B. Obin M.S. Greenberg A.S. Lipase-selective functional domains of perilipin A differentially regulate constitutive and protein kinase A-stimulated lipolysis.J. Biol. Chem. 2003; 278: 51535-51542Abstract Full Text Full Text PDF PubMed Scopus (107) Google Scholar, 17.Miyoshi H. Souza S.C. Zhang H.H. Strissel K.J. Christoffolete M.A. Kovsan J. Rudich A. Kraemer F.B. Bianco A.C. Obin M.S. et al.Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms.J. Biol. Chem. 2006; 281: 15837-15844Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar). Thus, the of perilipin in of basal and lipolysis in brown adipocytes of Peri mice and in vitro using brown from Peri (16.Zhang H.H. Souza S.C. Muliro K.V. Kraemer F.B. Obin M.S. Greenberg A.S. Lipase-selective functional domains of perilipin A differentially regulate constitutive and protein kinase A-stimulated lipolysis.J. Biol. Chem. 2003; 278: 51535-51542Abstract Full Text Full Text PDF PubMed Scopus (107) Google Scholar, 17.Miyoshi H. Souza S.C. Zhang H.H. Strissel K.J. Christoffolete M.A. Kovsan J. Rudich A. Kraemer F.B. Bianco A.C. Obin M.S. et al.Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms.J. Biol. Chem. 2006; 281: 15837-15844Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar). a direct to the of NE to increase thermogenesis, we that NE-induced IBAT thermogenesis is in Peri mice and that this is attributable to PKA-dependent lipolytic We that in NE increased IBAT temperature by and subsequently an increase in In the thermal increase in IBAT of Peri to with no in temperature In of the that mitochondrial function is and are normal in Peri mice these the critical role of perilipin phosphorylation and PKA-dependent lipolysis in IBAT thermogenesis. The normal thermal response to NE in Peri KO mice the demonstrated requirement of perilipin for lipolysis in adipocytes J. C. Gruia-Gray J. D. J. M. C. Kimmel A. Londos C. Perilipin in a mouse with adipocyte lipolysis, and resistance to diet-induced PubMed Scopus Google Scholar, J. J. D. A. M. D. L. of perilipin in and obesity in 2000; PubMed Scopus Google Scholar). in this study, NE to TAG hydrolysis constitutive in brown adipocytes from Peri KO mice of the absence of perilipin, basal lipolysis in BAT of Peri KO mice comparable to lipolysis in mice Thus, basal of TAG hydrolysis in IBAT of Peri KO mice sufficient fatty acids to support NE-stimulated thermogenesis. of normal adaptive thermogenesis in Peri KO mice is in the normal of mice to temperature in response to cold exposure J. J. D. A. M. D. L. of perilipin in and obesity in 2000; PubMed Scopus Google Scholar). in the absence of NE the increased rate of constitutive TAG hydrolysis in Peri KO mice is sufficient to BAT thermogenesis, that NE-dependent cell mechanisms or in lipolysis are required for NE-induced thermogenesis. In the IBAT response to NE in Peri mice that PKA-mediated perilipin phosphorylation and the TAG hydrolysis are critical for adaptive thermogenesis in brown In studies for the existence of critical NE-dependent mechanisms that be to initiate and sustain the IBAT thermal response. The and A. for providing animal support and The M. for providing the for support and the of a from This by of and of by the for on and of by the Obesity of and to by the and by the for