title: Pancreastatin, a chromogranin A-derived peptide, inhibits leptin and enhances UCP-2 expression in isolated rat adipocytes.
abstract: Leptin, the ob gene product, is an adipocyte-secreted hormone that centrally regulates weight by decreasing caloric intake and increasing energy expenditure. Expression of leptin is regulated by dietary status, insulin, glucocorticoids and catecholamines. Pancreastatin (PST), a chromogranin A-derived peptide, correlates with catecholamine levels, and may play a role in the physiology of stress, modulating endocrine secretion and metabolism. Thus, PST has been found to exert a lipolytic and anti-insulin effect in white adipocytes. The aim of the present work was to investigate a possible role of PST modulating the expression of key genes involved in lipid storage and metabolism: leptin, PPAR-gamma2, UCP-1 and UCP-2. We incubated isolated rat epididymal adipocytes with 100 nM PST for 16 and 24 h. Leptin, UCP-2 and UCP-1 mRNA levels were assessed by RT-PCR, followed by Southern blot. Leptin secretion was also measured by ELISA. PST inhibited leptin expression and secretion at 16-h incubation, but this effect was no longer observed after 24 h. On the other hand, PST stimulated the expression of UCP-2 after 16 h. However, the effect was still significant after 24 h. The inhibitory effect of PST on leptin expression and secretion and the stimulation of UCP-2 expression were prevented by blocking PKC. UCP-1 and PPR-gamma2 expression did not change after PST stimulation. Leptin differentially regulates the expression of key genes in the rat adipocyte, upregulating the expression of UCP-2 and inhibiting the expression and secretion of leptin by a mechanism that involves PKC activity. These effects may contribute to the metabolic action of catecholamines in physiological and pathophysiological conditions with increased sympathetic activity.
authors.affiliation: Department of Medical Biochemistry and Molecular Biology, School of Medicine, Investigation Unit, Virgen Macarena University Hospital, Av. Sanchez Pizjuan 4, Seville 41009, Spain.
authors.forename: C
authors.initials: C
authors.lastname: González-Yanes
authors.forename: V
authors.initials: V
authors.lastname: Sánchez-Margalet
mesh_terms: D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D053379:Chromogranin A; D007473:Ion Channels; D020738:Leptin / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D010187:Pancreatic Hormones / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D000071256:Uncoupling Protein 1; D000071246:Uncoupling Protein 2
chemical_list: D002352:Carrier Proteins; D053379:Chromogranin A; D007473:Ion Channels; D020738:Leptin; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D010187:Pancreatic Hormones; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; C000604373:Ucp1 protein, rat; C000604391:Ucp2 protein, rat; D000071256:Uncoupling Protein 1; D000071246:Uncoupling Protein 2; C050836:pancreastatin; D011493:Protein Kinase C