Increasing evidence indicates that brown adipose tissue (BAT) transplantation enhances whole-body energy metabolism in a mouse model of diet-induced obesity. However, it remains unclear whether BAT also has such beneficial effects on genetically obese mice. To address this issue, we transplanted BAT from C57/BL6 mice into the dorsal subcutaneous region of age- and sex-matched leptin deficient Ob/Ob mice. Interestingly, BAT transplantation led to a significant reduction of body weight gain with increased oxygen consumption and decreased total body fat mass, resulting in improvement of insulin resistance and liver steatosis. In addition, BAT transplantation increased the level of circulating adiponectin, whereas it reduced the levels of circulating free T3 and T4, which regulate thyroid hormone sensitivity in peripheral tissues. BAT transplantation also increased β3-adrenergic receptor and fatty acid oxidation related gene expression in subcutaneous and epididymal (EP) white adipose tissue. Accordingly, BAT transplantation increased whole-body thermogenesis. Taken together our results demonstrate that BAT transplantation may reduce obesity and its related diseases by activating endogenous BAT.

SUMMARYAbscisic acid (ABA) is an important phytohormone controlling responses to abiotic stresses and is sensed by proteins from the PYR/PYL/RCAR family. To explore the genetic contribution of PYLs toward ABA-dependent and ABA-independent processes, we generated and characterized high-order Arabidopsis mutants with mutations in the PYL family. We obtained a pyl quattuordecuple mutant and found that it was severely impaired in growth and failed to produce seeds. Thus, we carried out a detailed characterization of a pyl duodecuple mutant, pyr1pyl1/2/3/4/5/7/8/9/10/11/12. The duo-decuple mutant was extremely insensitive to ABA effects on seed germination, seedling growth, stomatal closure, leaf senescence, and gene expression. The activation of SnRK2 protein kinases by ABA was blocked in the duodecuple mutant, but, unexpectedly, osmotic stress activation of SnRK2s was enhanced. Our results demonstrate an important role of basal ABA signaling in growth, senescence, and abscission and reveal that PYLs antagonize ABA-independent activation of SnRK2s by osmotic stress.