Obesity Research Today is a free monthly online journal that collates and summarizes the latest research about Obesity, including details on health, diet, prevention, exercise. | ||||||||
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Inactivation of signal transducer and activator of transcription 3 in proopiomelanocortin (Pomc) neurons causes decreased pomc expression, mild obesity, and defects in compensatory refeeding.Xu AW, Ste-Marie L, Kaelin CB, Barsh GS Department of Genetics, Stanford University School of Medicine, San Francisco, California 94143, USA. axu@diabetes.ucsf.edu Leptin is an adipocyte-derived hormone that signals body energy status to the brain by acting on multiple neuronal subgroups in the hypothalamus, including those that express proopiomelanocortin (Pomc) and agouti-related protein (Agrp). Signal transducer and activator of transcription 3 (Stat3) is an important intracellular signaling molecule activated by leptin, and previous studies have shown that mice carrying a mutated leptin receptor that abolished Stat3 binding are grossly obese. To determine the extent to which Stat3 signaling in Pomc neurons was responsible for these effects, we constructed Pomc-specific Stat3 mutants using a Cre recombinase transgene driven by the Pomc promoter. We find that Pomc expression is diminished in the mutant mice, suggesting that Stat3 is required for Pomc transcription. Pomc-specific Stat3 female mutant mice exhibit a 2-fold increase in fat pad mass but only a slight increase in total body weight. Mutant mice remain responsive to leptin-induced hypophagia and are not hypersensitive to a high-fat diet; however, mutant mice fail to mount a normal compensatory refeeding response. These results demonstrate a requirement for Stat3 in transcriptional regulation of Pomc but indicate that this circuit is only one of several components that underlie the neuronal response to leptin and the role of Stat3 in that response. Published 20 December 2006 in Endocrinology, 148(1): 72-80.
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