Project description:Various physiological stimuli, such as cold environment, diet, and hormones, trigger brown adipose tissue (BAT) to produce heat through sympathetic nervous system (SNS)- and -adrenergic receptors (ARs). The AR stimulation increases intracellular cAMP levels through heterotrimeric G proteins and adenylate cyclases, but the processes by which cAMP modulates brown adipocyte function are not fully understood. Here we described that specific ablation of cAMP production in brown adipocytes led to reduced lipolysis, mitochondrial biogenesis, uncoupling protein 1 (Ucp1) expression, and consequently defective adaptive thermogenesis. Elevated cAMP signaling by sympathetic activation inhibited Salt-inducible kinase 2 (Sik2) through protein kinase A (PKA)-mediated phosphorylation in brown adipose tissue. Inhibition of SIKs enhanced Ucp1 expression in differentiated brown adipocytes and Sik2 knockout mice exhibited enhanced adaptive thermogenesis at thermoneutrality in an Ucp1-dependent manner. Taken together, our data indicate that suppressing Sik2 by PKA-mediated phosphorylation is a requisite for SNS-induced Ucp1 expression and adaptive thermogenesis in BAT, and targeting Sik2 may present a novel therapeutic strategy to ramp up BAT thermogenic activity in humans.
Project description:Analysis of brown adipose tissue from Yin Yang 1 (YY1) brown fat specific knockout mice fed a high fat diet for 3 months. YY1 deficiency in brown adipose tissue leads to strong thermogenic deficiency. The goal was to identify the genes controlled by YY1 responsible of brown fat defective function.
Project description:We report the application of sequencing technology for high-throughput profiling of PPARα/γ in mammalian cells. By obtaining over 3 billion bases of sequence from chromatin immunoprecipitated DNA, we generated genome-wide chromatin-state maps of mouse brown adipose tissue. We find that PPARα binds to a subset of PPARγ sites, suggesting a potential redundancy in which PPARα function may not be necessary in brown adipose tissue.While PPARα may not itself be necessary for BAT function, shared targets regulation by PPARα and PPARγ may nonetheless reveal relevant biology in this tissue.This study provides a framework for the application of comprehensive chromatin profiling towards characterization of PPARα/γ regulation in mouse brown adipose tissue.
Project description:Analysis of brown adipose tissue from Yin Yang 1 (YY1) brown fat specific knockout mice fed a high fat diet for 3 months. YY1 deficiency in brown adipose tissue leads to strong thermogenic deficiency. The goal was to identify the genes controlled by YY1 responsible of brown fat defective function. Control mice YY1flox/flox versus YY1flox/flox; Ucp1Cre were fed a high fat diet for 3 months
Project description:Gene expression profile from brown adipose tissues of Prdm16 knockout and wile type mice. Prdm16 is a transcription factor that regulates the thermogenic gene program in brown and beige adipocytes. However, whether Prdm16 is required for the development or physiological function of brown adipose tissue (BAT) in vivo has been unclear. By analyzing mice that selectively lacked Prdm16 in the brown adipose lineage, we found that Prdm16 was dispensable for embryonic BAT development.
Project description:Cold and nutrient activated brown adipose tissue (BAT) is capable of increasing systemic energy expenditure via uncoupled respiration and secretion of endocrine factors thereby protecting mice against diet-induced obesity and improving insulin response and glucose tolerance in men. Long non-coding RNAs (lncRNAs) have recently been identified as fine tuning regulators of cellular function. While certain lncRNAs have been functionally characterised in adipose tissue, their overall contribution in the activation of BAT remains elusive. We identified lncRNAs correlating to inter- scapular brown adipose tissue (iBAT) function in high fat diet (HFD) and cold stressed mice. We focused on Gm15551 which has an adipose tissue specific expression profile, is highly upregulated during adipogenesis and downregulated by β-adrenergic activation in mature adipocytes. Albeit we performed comprehensive transcriptional and adipocyte physiology profiling in vitro and in vivo, we could not detect an effect of gain or loss of function of Gm15551.
