Differential regulation of functional responses by beta-adrenergic receptor subtypes in brown adipocytes.
Brown adipose tissue contains both beta(1)- and beta(3)-adrenergic receptors (beta-ARs), and whereas both receptor subtypes can activate adenylyl cyclase, recent studies suggest that these subtypes have different pharmacological properties and may serve different signaling functions. In this study, primary brown adipocyte cultures were used to determine the role of beta-AR subtypes in mediating lipolysis and uncoupling protein-1 (UCP1) gene expression, elicited by the physiological neurohormone norepinephrine (NE). NE increased both lipolysis and UCP1 mRNA levels in brown adipocyte cultures; the beta(1)-receptor-selective antagonist CGP-20712A strongly antagonized the increase in UCP1 gene expression but had little effect on lipolysis. The beta(3)-receptor-selective agonist CL-316243 (CL) also increased lipolysis and UCP1 mRNA levels, yet CL was more potent in stimulating lipolysis than UCP1 gene expression. NE also increased the phosphorylation of cAMP response element-binding protein (CREB) and perilipin (PL), both of which are protein kinase A substrates that are differentially targeted to the nucleus and lipid droplets, respectively. beta(1)-receptor blockade inhibited NE-stimulated phosphorylation of CREB but not PL. The results suggest that beta-AR subtypes regulate different physiological responses stimulated by NE in brown adipocyte cultures in part by differentially transducing signals to subcellular compartments.
Cellular and Clinical Neurobiology Program, Department of Psychiatry and Behavioral Neurosciences, Wayne State University, School of Medicine, Detroit, Michigan 48201, USA. Archana.Chaudhry@wl.com
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Chaudhry
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Granneman
D051698:Activating Transcription Factor 2; D017667:Adipocytes / Q000502:physiology*; D002001:Adipose Tissue, Brown / Q000166:cytology*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D046508:Culture Techniques; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D007473:Ion Channels; D008066:Lipolysis; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D024101:Mitochondrial Proteins; D009638:Norepinephrine / Q000502:physiology; D000070778:Perilipin-1; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism; D000071256:Uncoupling Protein 1
D051698:Activating Transcription Factor 2; D002352:Carrier Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D000070778:Perilipin-1; D010750:Phosphoproteins; D011943:Receptors, Adrenergic, beta; D014157:Transcription Factors; C000604373:Ucp1 protein, rat; D000071256:Uncoupling Protein 1; D017868:Cyclic AMP-Dependent Protein Kinases; D009638:Norepinephrine