SUMMARY Obesity develops due to altered energy homeostasis favoring fat storage. Here we describe a novel transcription co-regulator for adiposity and energy metabolism, TRIP-Br2 (also called SERTAD2). TRIP-Br2 null mice are resistant to obesity and obesity-related insulin resistance. Adipocytes of the knockout (KO) mice exhibited greater stimulated lipolysis secondary to enhanced expression of hormone sensitive lipase (HSL) and β3-adrenergic (Adrb3) receptors. The KOs also exhibit higher energy expenditure due to increased adipocyte thermogenesis and oxidative metabolism by up-regulating key enzymes in respective processes. Our data show for the first time that a cell cycle transcriptional co-regulator, TRIP-Br2, modulates fat storage through simultaneous regulation of lipolysis, thermogenesis and oxidative metabolism. These data together with the observation that TRIP-BR2 expression is selectively elevated in visceral fat in obese humans suggests that this transcriptional co-regulator is a novel therapeutic target for counteracting the development of obesity, insulin resistance and hyperlipidemia
