Ire1a in pomc neurons is required for thermogenesis and glycemia

Whether neuronal inositol-requiring enzyme 1 (Ire1) is required for the proper regulation of energy balance and glucose homeostasis is unclear. We found that proopiomelanocortin (Pomc)-specific deficiency of Ire1a accelerated diet-induced obesity concomitant with a decrease in energy expenditure. This hypometabolic phenotype included deficits in thermogenic responses to diet and cold exposure as well as "beiging" of white adipose tissue. We also demonstrate that loss of Ire1a in Pomc neurons impaired whole-body glucose and insulin tolerance as well as hepatic insulin sensitivity. At the cellular level, deletion of Ire1a in Pomc neurons elevated hypothalamic endoplasmic reticulum (ER) stress and predisposed Pomc neurons to leptin and insulin resistance. Together, the current studies extend and confirm conclusions that Ire1a-Xbp1s and associated molecular targets link ER stress in arcuate Pomc neurons to aspects of normal energy and glucose homeostasis.