The Nutritional Induction of COUP-TFII Gene Expression in Ventromedial Hypothalamic Neurons Is Mediated by the Melanocortin Pathway

et al. (2010) The Nutritional Induction of COUP-TFII Gene Expression in Ventromedial Hypothalamic Neurons Is Mediated by the Melanocortin Pathway. PLoS ONE 5(10): e13464. doi:10.1371/journal.pone.0013464 The Nutritional Induction of COUP-TFII Gene Expression in Ventromedial Hypothalamic Neurons Is Mediated by the Melanocortin Pathway Lina Sabra-Makke 0 1 Ce cile Tourrel-Cuzin 0 1 Raphae l G. P. Denis 0 1 Marthe Moldes 0 1 Jean-Paul 0 1 Pe gorier 0 1 Serge Luquet 0 1 Mireille Vasseur-Cognet 0 1 Pascale Bossard 0 1 Bernadette Breant, INSERM, France 0 Funding: This work was supported by grants from ALFEDIAM-Antadir, France , 2008, and from the BQR (Bonus Qualite Recherche) , Paris V University, France, 2007. L.S.M. is the recipient of a doctoral fellowship from the Conseil national de la recherche scientifique du Liban and the Fondation pour la Recherche Me dicale. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript 1 1 Institut Cochin, Universite Paris Descartes, Department of Endocrinology, Metabolism and Cancer, CNRS (UMR 8104) , Paris, France, 2 INSERM, U1016, Paris , France , 3 Laboratoire de Biologie et Pathologie du Pancre as Endocrine, Unite ''Biologie Fonctionnelle & Adaptative'', Universite Paris Diderot-Paris 7, CNRS EAC 4413, Paris, France , 4 Team HERGE , Unite ''Functional and Adaptive Biology, Biologie Fonctionnelle & Adaptative'', Universite Paris Diderot-Paris 7, CNRS EAC 4413 , Paris , France Background: The nuclear receptor chicken ovalbumin upstream promoter transcription factor II (COUP-TFII) is an important coordinator of glucose homeostasis. We report, for the first time, a unique differential regulation of its expression by the nutritional status in the mouse hypothalamus compared to peripheral tissues. Methodology/Principal Findings: Using hyperinsulinemic-euglycemic clamps and insulinopenic mice, we show that insulin upregulates its expression in the hypothalamus. Immunofluorescence studies demonstrate that COUP-TFII gene expression is restricted to a subpopulation of ventromedial hypothalamic neurons expressing the melanocortin receptor. In GT1-7 hypothalamic cells, the MC4-R agonist MTII leads to a dose dependant increase of COUP-TFII gene expression secondarily to a local increase in cAMP concentrations. Transfection experiments, using a COUP-TFII promoter containing a functional cAMP responsive element, suggest a direct transcriptional activation by cAMP. Finally, we show that the fed state or intracerebroventricular injections of MTII in mice induce an increased hypothalamic COUP-TFII expression associated with a decreased hepatic and pancreatic COUP-TFII expression. Conclusions/Significance: These observations strongly suggest that hypothalamic COUP-TFII gene expression could be a central integrator of insulin and melanocortin signaling pathway within the ventromedial hypothalamus. COUP-TFII could play a crucial role in brain integration of circulating signal of hunger and satiety involved in energy balance regulation. - The hypothalamus receives information from circulating nutrients and hormones and integration of these signals by appropriate neurocircuitry will in turn translate into adaptive metabolic and behavioral responses in order to sustain energy balance. Food intake modulation, insulin secretion and peripheral glucose metabolism together with endocrine regulation are part of this integrated response. Any disturbance of this mechanism leads to metabolic diseases such as obesity and diabetes [1,2]. Nuclear receptors are part of a family of ligand-activated transcription factor such as PPARs, LXRs, RXR, involved in the regulation of many key metabolic functions both at the central and peripheral level. Among these transcription factors, our team has focused its attention on the Chicken Ovalbumin Upstream Promoter-Transcription Factor II (COUP-TFII also named NR2F2). COUP-TFII is an orphan member of the steroid/ thyroid hormone receptor superfamily with no identified physiological ligand. It binds DNA by a zinc finger motif on a variety of hormone responsive elements that contain direct or inverted imperfect AGGTCA repeats with various spacings [3]. COUPTFII is involved in the control of development, cellular differentiation, growth and metabolism [4,5,6]. In terms of metabolic control, we and others showed its functional role in respect to genetic programs associated with insulin biosynthesis and secretion in pancreatic beta cells [7,8], in the regulation of lipid utilization/cholesterol homeostasis in skeletal muscle cells [9] and in white adipose tissue development and energy metabolism [10]. The fact that heterozygous COUP-TFII gene inactivation mouse models, i.e conditional beta cells [8] or complete invalidation [10] (50% decrease in COUP-TFII expression) displayed a strong phenotype suggests that any small variations of COUP-TFII expression does lead to a disturbed physiology. Interestingly, its expression is modulated by the nutritional status in several tissues. We previously reported that COUP-TFII expression was reduced in the pancreas and liver of mice refed onto with a carbohydrate rich diet [7]. In fact, COUP-TFII gene expression is decreased by secreted insulin in response to glucose in pancreatic beta cells and by insulin and glucose in hepatocytes [7]. In situ hybridization data showed that COUP-TFII mRNA was also expressed in the hypothalamus [11,12]. As an actor of glucose homeostasis, whose expression is modulated by the nutritional status in several tissues and as it is expressed in the hypothalamus whose function is central to energy homeostasis, it was of interest to decipher the regulation of COUPTFII expression by the nutritional status in the hypothalamus. In this paper, we report 1) a differential regulation of COUPTFII mRNA levels by the nutritional status with an induction of its expression in the hypothalamus in the fed state 2) COUP-TFII protein expression in a subpopulation of ventromedial hypothalamic neurons 3) COUP-TFII expression in the hypothalamus and in a hypothalamic cell line being controlled by the melanocortin pathway leading to a direct COUP-TFII transcriptional activation. Hypothalamic COUP-TFII expression is induced by the fed state in adult mice Previous studies from our lab and from others had observed an expression of COUP-TFII mRNA in embryonic and adult hypothalamus [12,13,14]. From our previous studies on COUPTFII mRNA regulation in liver and pancreas, we looked at the regulation of COUP-TFII mRNA levels in the hypothalamus of C57bl/6J adult mice according to their nutritional status. Mice were subjected to a 24 hours fast and compared with mice refed a regular chow diet for 6 hours, which causes a major switch leading to elevated plasma glucose (from 102610.2 mg/dl at the fasted state to 16569.5 mg/dl in the fed mice) and plasma insulin levels (from 0.660.2 at the fasted state to 1.960.3 in the (...truncated)