FOXO1-KLF10 reinforcing loop promotes adipose lipolysis to facilitate exercise-induced anti-obesity effect in male mice
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ABSTRACT: Exercise is recognized to be an effective way in the combat against obesity and related metabolic disorders, but the underlying mechanism is incompletely understood. Krüppel-like factor 10 (KLF10) is a transcription factor participating in diverse biological processes. KLF10 expression is abundant in adipose tissue, but its role in obesity is not well defined. Here, we show that exercise could facilitate adipocyte-derived KLF10 expression via the SIRT1/FOXO1 pathway. Adipocyte-specific knockout of KLF10 (KLF10AKO) blunts exercise-promoted white adipose browning, energy expenditure, fat loss, and glucose tolerance in diet-induced obese (DIO) mice. On the contrary, adipocyte-specific transgenic expression of KLF10 in mice (KLF10ATG) enhanced the abovementioned metabolic benefits induced by exercise. Mechanistically, KLF10 interacts with FOXO1 and facilitates the recruitment of KDM4A to form a ternary complex on the promoter regions of the Pnpla2 and Lipe genes to promote the expression of these key lipolytic genes, therefore facilitating lipolysis to defend against DIO in mice. As a newfound downstream effector responding to exercise, adipose KLF10 could act as a potential target in the fight against obesity
Project description:Activation of brown fat thermogenesis increases energy expenditure and alleviates obesity. Sympathetic nervous system (SNS) is important in brown/beige adipocyte thermogenesis. Here we discover a novel fat-derived “adipokine” neurotrophic factor neurotrophin 3 (NTF3) and its receptor Tropomyosin receptor kinase C (TRKC) as key regulators of SNS growth and innervation in adipose tissue. NTF3 is highly expressed in brown/beige adipocytes, and potently stimulates sympathetic neuron neurite growth. NTF3/TRKC regulates a plethora of pathways in neuronal axonal growth and elongation. Adipose tissue sympathetic innervation is significantly increased in mice with adipocyte-specific NTF3 overexpression, but profoundly reduced in mice with TRKC haploinsufficiency (TRKC+/-). Increasing NTF3 via pharmacological or genetic approach promotes beige adipocyte development, enhances cold-induced thermogenesis and protects against diet-induced obesity (DIO); whereas TRKC+/- mice or SNS TRKC deficient mice are cold intolerant and prone to DIO. Thus, NTF3 is an important fat-derived neurotrophic factor regulating SNS innervation, energy metabolism and obesity.
Project description:Exercise benefits M2 macrophage polarization, energy homeostasis and protects against obesity partially through exercise-induced circulating factors. Here, by unbiased quantitative proteomics on serum samples from sedentary and exercised mice, we identify parvalbumin as a circulating factor suppressed by exercise. Parvalbumin functions as a non-competitive CSF1R antagonist to inhibit M2 macrophage activation and energy expenditure in adipose tissue. More importantly, serum concentrations of parvalbumin positively correlate with obesity in mouse and human, while treating mice with a recombinant parvalbumin blocker prevents its interaction with CSF1R and promotes M2 macrophage polarization and ameliorates diet-induced obesity. Thus, although further studies are required to assess the significance of parvalbumin in mediating the effects of exercise, our results implicate parvalbumin as a potential therapeutic strategy against obesity.
Project description:To assess changes in expression level of various chemokines and their receptors on diet-induced obesity, we analysed gene expression in adipose tissue of C56BL/6J mice fed a high-fat (HF) diet or normal chow diet for 8 weeks. HF diet-induced obese (DIO) mice showed adipose tissue inflammation and insulin resistance. Comprehensive gene expression analysis showed that MCP-1–CCR2 and CCL5–CCR5 signalling in epididymal white adipose tissue (eWAT) were enhanced during the development of obesity. Surprisingly, the gene expression of Cx3cl1 was decreased in the eWAT of DIO mice compared with lean mice. While Cx3cr1 expression showed no significant difference between DIO and lean mice. Decreased CX3CL1-CX3CR1 signalling in adipose tissue may also be involved in the development of obesity-induced adipose tissue inflammation and insulin resistance.
Project description:Obesity is a major public health concern that is associated with negative health outcomes. Exercise and dietary restriction are commonly recommended to prevent, or combat obesity. The purpose of this study was to examine the mechanism by which aberrantly expressed genes in the hypothalamic arcuate nucleus (ARC) of diet-induced obese (DIO) rats is attenuated through voluntary exercise. Methods: A transcriptomic approach assessed novel genes in the ARC that affect DIO by voluntary wheel running and a combined approach of physiology, pharmacology, transcriptomic and bioinformatics analysis were used to evaluate the role of miR in the reversal of obesity. Results: Exercise attenuated body weight gain, decreased fat mass, and restored gene expression in the ARC. As high-fat diet (HFD) consumption can cause dysregulation of satiety/hunger regulation mechanisms in the ARC, we outlined transcriptional clusters which depicted alterations in patterns of gene expression through running. Among them were genes involved with inflammation and cellular structure. To uncover regulatory mechanisms governing gene expression in DIO attenuation, we explored the role of miR-211, as it has been implicated in systemic inflammation. The DIO overexpression of miR-211 was ameliorated by exercise, demonstrating its pivotal role in the regulation of inflammation in the ARC. Further, in vivo central administration of miR-211-mimic affected the expression of immunity and cell cycle related genes. By comparing genes attenuated by running and genes downregulated by miR-211, we produced a list of candidate genes that might be involved in the modulation by miR-211 in attenuating obesity by exercise. Conclusion: This research suggests that exercise may have a rescue effect on obesity through changes in gene expression that are mediated partially though miR-211.
Project description:While adipocytes are critical pillars of energy metabolism, their dysfunction is linked to adipose tissue (AT) inflammation, insulin resistance, and ectopic lipotoxicity in cardiometabolic diseases. However, he mechanisms causing adipocyte inflammation and insulin resistance remain unclear. Here, we show that excess cholesterol induces adipocyte dysfunction, which is suppressed by the transcription factor Nfe2l1 (nuclear factor erythroid derived-2, like-1). Nfe2l1 is required to sustain proteasome function in adipocytes and proteotoxic stress induces adipocyte inflammation via the activation of Atf3. In humans, the Nfe2l1-proteasome pathway is inversely correlated to body mass index (BMI) in an adipose-depot specific manner. In mice, loss of adipocyte Nfe2l1 caused AT inflammation with a pronounced infiltration of macrophages and T cells. Mice lacking adipocyte Nfe2l1 displayed severe adipocyte dysfunction during diet-induced obesity (DIO), characterized by lower adipokine levels, steatosis, glucose intolerance and insulin resistance. Nfe2l1ΔAT mice on an Apoe-deficient (Apoe-/-) background fed a cholesterol-rich Western Diet (WD), developed a lipoatrophy-like syndrome, dyslipidemia, and enhanced atherosclerosis. Our results reveal an important role for proteasome-mediated proteostasis in adipocytes and indicate that Nfe2l1 is linked to metabolic health in humans and preclinical mouse models. Promoting proteostasis in adipocytes may thus alleviate inflammation in obesity, potentially averting adverse cardiometabolic outcomes.
Project description:Overeating disorders significantly contribute to worldwide incidences of obesity. Available treatments are limited. Here, we discovered that long-term chemogenetic activation of ventrolateral periaqueductal gray (vlPAG) GABAergic cells rescue obesity of high-fat diet induced obesity (DIO) mice. This was associated with the recovery of enhanced mIPSCs, decreased food intake, increased energy expenditure, and inguinal white adipose tissue (iWAT) browning. In vivo calcium imaging confirmed vlPAG GABAergic suppression for DIO mice, with corresponding reduction in intrinsic excitability. Single-nucleus RNA sequencing identified transcriptional expression changes in GABAergic cell subtypes in DIO mice, highlighting Cacna2d1 as of potential importance. Overexpressing Cacna2d1 in vlPAG GABAergic cells of DIO mice rescued enhanced mIPSCs and calcium response, reversed obesity, and therefore presented here as a potential target for obesity treatment.
Project description:Activated brown adipose tissue contributes to control of energy and glucose homeostasis in rodents and humans. Defining cell-autonomous processes underlying BAT differentiation and activation may thus reveal novel therapeutic targets for obesity and type 2 diabetes mellitus intervention. Here we show that ageing- and obesity-associated demises in BAT function coincide with down-regulation of mature microRNAs in BAT in the presence of reduced expression of the critical microRNA processing enzyme Dicer1. To mimic this partial down-regulation of microRNA processing in obesity and ageing, we inactivated one allele of Dicer1 selectively in BAT of mice. BAT- restricted heterozygosity of Dicer1 caused glucose intolerance in lean mice and aggravated diet-induced-obesity (DIO)-evoked deterioration of glucose homeostasis. Using combinatorial analyses of altered microRNA-expression in BAT during in vitro preadipocyte commitment and mouse models of progeria, longevity and DIO, we identified 23 microRNAs dysregulated among these conditions. Of these, we identified miR-328 as a novel regulator of BAT differentiation. miR-328 over-expression promotes BAT-differentiation and impairs muscle progenitor commitment, while reducing miR-328 expression blocks BAT specification. We validated the ß-Secretase Bace1 as a target of miR-328, which is consequently over-expressed in BAT of obese and premature ageing mice. Reducing Bace1 expression enhances brown adipocyte, while impairing myogenic differentiation in vitro. In vivo small-molecule Bace1 inhibition in obese mice delayed DIO-induced weight gain, ameliorated obesity-associated deterioration of glucose metabolism and improved insulin sensitivity. Collectively, these experiments reveal reduced Dicer1-miR-328-Bace1 axis in presence of generalized impairment of microRNA processing in ageing and obesity as a novel determinant of ageing- and obesity-associated decline in BAT function. This may define in vivo Bace1-inhibition as an innovative therapeutic approach to not only target age-related neurodegenerative diseases but at the same time improving age-related impairment of BAT-function and metabolism. C57BL/6 mice ( 4 weeks of age) were treated with a calory-rich, high-sugar high-fat diet (HFD) for a course of 4 weeks. Then groups were stratified and one group continued to receive HFD (BAT13-15) or HFD supplemented with an experimental small-molecule Bace 1 inhibitor (BAT17, 33, 35).
Project description:Diet-induced obesity (DIO) predisposes individuals to insulin resistance, and adipose tissue has a major role in the disease. Insulin resistance can be induced in cultured adipocytes by a variety of treatments, but what aspects of the in vivo responses are captured by these models remains unknown. We use global RNA sequencing to investigate changes induced by TNF-a, hypoxia, dexamethasone, high insulin, and a combination of TNF-a and hypoxia, comparing the results to the changes in white adipose tissue from DIO mice. We found that different in vitro models capture distinct features of DIO adipose insulin resistance, and a combined treatment of TNF-a and hypoxia is most able to mimic the in vivo changes. Using genome-wide DNase I hypersensitivity followed by sequencing, we further examined the transcriptional regulation of TNF-a-induced insulin resistance, and we found that C/EPBM-CM-^_ key regulator of adipose insulin resistance. RNA-seq for 6 insulin resistance conditions and 2 control conditions, Dnase hypersensitivity-seq of 4 conditions and 1 control condition, ChIP-seq on p65 after TNFa treatment.
Project description:Increases in organismal energy expenditure, as during cold exposure or exercise training, can improve metabolic health. This process is dependent also on brown adipose tissue (BAT) thermogenesis in mice and humans. Understanding and harnessing the molecular circuits activating BAT function is thus of great interest to devise novel approaches to counteract obesity and type 2 diabetes (T2D). In contrast to protein-coding genes, the role of long noncoding RNAs (lncRNAs) during BAT differentiation and function remains poorly understood. To address this, we performed RNA-Seq and identified the maternal allele-specific (imprinted) lncRNA H19 increased upon cold-mediated BAT activation and decreased upon chronic diet-induced obesity (DIO) BAT dysfunction. An inverse correlation of H19 expression with body-mass indices (BMI) was observed in a cohort of >160 lean and obese humans. H19 silencing impaired adipogenesis and oxidative metabolism in brown but not white adipocytes, while H19 gain-of-function increased nutrient oxidation and mitochondrial respiration, thus supporting a BAT-regulatory role for H19. In vivo H19 overexpression protected against DIO, improved insulin sensitivity and rescued DIO-mediated defects in energy expenditure in conjunction with improved mitochondrial biogenesis. In contrast, BAT-selective H19 loss decreased energy dissipation and sensitized towards high fat diet-induced body weight gains. When investigating other parent-of-origin specific, monoallelically expressed genes, we strikingly observed that paternally expressed genes (PEGs) were largely absent from BAT and coordinately downregulated during brown adipogenesis, whilst the same gene set was robustly expressed in white fat stores, a phenomenon not observed for maternally expressed genes (MEGs). Using H19 loss- and gain-of-function in primary adipocytes, we demonstrate that H19 acts as ‘PEG gatekeeper’ in brown, not white adipocytes, potentially due to recruitment of PEG-inactivating H19-MBD1 complexes in mature brown adipocytes. The exclusive PEG expression in white adipose tissuer could underly the observed susceptibility of mice exhibiting high PEG abundances towards DIO-evoked weight gain. Collectively, we here define novel roles for the imprinted lncRNA H19 in brown adipocyte differentiation and function in vitro, control of energy expenditure in vivo and repression of paternal allele-specific gene expression in BAT. This has far-reaching implications for our understanding of how monoallelical gene expression affects metabolic eustasis in both rodent models and, potentially, human patients.