Sirtuin 6 supra-physiological overexpression in hypothalamic pro-opiomelanocortin neurons promotes obesity via the hypothalamus-adipose axis.

Sirtuin 6 (Sirt6), a member of the Sirtuin family, has important roles in maintaining glucose and lipid metabolism. Our previous studies demonstrated that the deletion of Sirt6 in pro-opiomelanocortin (POMC)-expressing cells by the loxP-Cre system resulted in severe obesity and hepatic steatosis. However, whether overexpression of Sirt6 in hypothalamic POMC neurons could ameliorate diet-induced obesity is still unknown. Thus, we generated mice specifically overexpressing Sirt6 in hypothalamic POMC neurons (PSOE) by stereotaxic injection of Cre-dependent adeno-associated viruses into the arcuate nucleus of Pomc-Cre mice. PSOE mice showed increased adiposity and decreased energy expenditure. Furthermore, thermogenesis of BAT and lipolysis of WAT were both impaired, caused by reduced sympathetic nerve innervation and activity in adipose tissues. Mechanistically, Sirt6 overexpression decreasing STAT3 acetylation, thus lowering POMC expression in the hypothalamus underlined the observed phenotypes in PSOE mice. These results demonstrate that Sirt6 overexpression specifically in the hypothalamic POMC neurons exacerbates diet-induced obesity and metabolic disorders via the hypothalamus-adipose axis.

Pterostilbene, a Bioactive Component of Blueberries, Alleviates Renal Interstitial Fibrosis by Inhibiting Macrophage-Myofibroblast Transition.

Pterostilbene (PTB) is a derivative of resveratrol present in grapes and blueberries. PTB is structurally similar to resveratrol, possessing properties such as being analgesic, anti-aging, antidiabetic, anti-inflammatory, anti-obesity, anti-oxidation, cholesterol-reductive, and neuroprotective. However, there have not been reports on the effect of PTB on macrophage-myofibroblast transition (MMT) induced fibrosis in kidney. In this study, we investigated the antifibrotic effects of PTB on the in vivo mouse unilateral ureteral obstruction (UUO) model and in vitro MMT cells. Kidneys subjected to UUO with PTB treatment were collected for the investigation of PTB mediating MMT derived renal interstitial fibrosis. We conducted kidney RNA-seq transcriptomes and TGF-[Formula: see text]1-induced bone marrow-derived macrophages assays to determine the mechanisms of PTB. We found that PTB treatment suppressed the interstitial fibrosis in UUO mice. PTB also attenuated the number of MMT cells in vivo and in vitro. The transcriptomic analysis showed that CXCL10 may play a central role in the process of PTB-treated renal fibrosis. The siRNA-mediated CXCL10 knockdown decreased the number of MMT cells in TGF-[Formula: see text]1-induced bone marrow-derived macrophages. Our results suggested that PTB attenuated renal interstitial fibrosis by mediating MMT by regulating transcriptional activity of CXCL10.

Sirt6 in pro-opiomelanocortin neurons controls energy metabolism by modulating leptin signaling.

OBJECTIVE: Sirt6 is an essential regulator of energy metabolism in multiple peripheral tissues. However, the direct role of Sirt6 in the hypothalamus, specifically pro-opiomelanocortin (POMC) neurons, controlling energy balance has not been established. Here, we aimed to determine the role of Sirt6 in hypothalamic POMC neurons in the regulation of energy balance and the underlying mechanisms. METHODS: For overexpression studies, the hypothalamic arcuate nucleus (ARC) of diet-induced obese mice was targeted bilaterally and adenovirus was delivered by using stereotaxic apparatus. For knockout studies, the POMC neuron-specific Sirt6 knockout mice (PKO mice) were generated. Mice were fed with chow diet or high-fat diet, and body weight and food intake were monitored. Whole-body energy expenditure was determined by metabolic cages. Parameters of body composition and glucose/lipid metabolism were evaluated. RESULTS: Sirt6 overexpression in the ARC ameliorated diet-induced obesity. Conversely, selective Sirt6 ablation in POMC neurons predisposed mice to obesity and metabolic disturbances. PKO mice showed an increased fat mass and food intake, while the energy expenditure was decreased. Mechanistically, Sirt6 could modulate leptin signaling in hypothalamic POMC neurons, with Sirt6 deficiency impairing leptin-induced phosphorylation of signal transducer and activator of transcription 3. The effects of leptin on reducing food intake and body weight and leptin-stimulated lipolysis were also impaired. Moreover, Sirt6 inhibition diminished the leptin-induced depolarization of POMC neurons. CONCLUSIONS: Our results reveal a key role of Sirt6 in POMC neurons against energy imbalance, suggesting that Sirt6 is an important molecular regulator for POMC neurons to promote negative energy balance.