Project description:Recently white adipose tissues (WAT) have been shown to be able to generate heat upon cold exposure through the expression of uncoupling protein-1 (UCP1), a molecule regulating mitochondrial proton gradient. Although the role of UCP1 has been extensively investigated in adipocytes, it is currently unknown whether UCP1 in the microenvironment of WAT such as adipose-tissue macrophages (ATM) could play a role in thermogenesis. Given the critical role of hypoxia in regulating obesity and insulin resistance, we challenged our myeloid-specific hypoxia-inducible factor-1α (Hif-1α) knockout (KO) mice to high fat diet and observed that these mice were not only protected from diet-induced obesity but also resistant to the body temperature changes upon cold exposure, the latter effect being completely lost upon surgical removal of WAT. Mechanistically, ATM deficient for HIF-1α generated heat production through increased expression of UCP1 and increased mitochondrial functions, all of which lead to an enhanced lipolysis in neighboring adipocytes. Lastly, we observed a number of co-localized areas between UCP-1 and CD68 in WAT of lean mice as well as individuals whereas such areas were not observed in an obese mice or human subjects. In conclusion, we demonstrate a novel mechanism by which ATM regulate obesity through UCP1-mediated heat generation.
Project description:Obesity is associated with impaired β-adrenergic receptor (Adrb1-3) signaling and lipolysis, leading to aberrant white adipose tissue (WAT) growth. WAT research has been centered on transcriptional and posttranslational regulations, but posttranscriptional regulation and mRNA modifications are poorly understood. Here, we unveil a METTL14/N6-methyladenosine (m6A) paradigm guiding β-adrenergic signaling and lipolysis. METTL14 complex installs m6A on RNA, regulating mRNA fate and translation. We found that feeding and insulin increased adipose Mettl14 and m6A levels. Adipose Mettl14 and m6A were upregulated in high fat diet (HFD)-induced obesity. Ablation of adipose Mettl14 decreased Adrb2, Adrb3, Atgl (encoding lipase), and Cig-58 (Atgl activator) transcript m6A contents while increasing their translation and protein levels, thereby enhancing adipose β-adrenergic signaling and lipolysis. Consequently, adipocyte-specific Mettl14 knockout mice were resistant to HFD-induced obesity, insulin resistance, glucose intolerance, and NAFLD. These results unravel a METTL14/m6A-based epitranscriptomic mechanism governing β-adrenergic signaling, lipolysis, and adipose growth in health and disease.
Project description:Middle-aged obesity, characterized by excessive fat accumulation and systemic energy imbalance, often precedes various health complications. Recent research has unveiled a surprising link between DNA damage response and energy metabolism. Here, we explore the role of Eepd1, a DNA repair enzyme, in regulating adipose tissue function and obesity onset. Eepd1 is primarily expressed in adipose tissue, where its downregulation or deletion accelerates obesity development. We show that Eepd1 ablation in vivo hinders PKA activation, thereby inhibiting lipolysis and thermogenesis in adipose tissue. leading to obesity progression and dysregulation of glucose metabolism. This study reveals Eepd1’s unexpected role in promoting adipose lipolysis and thermogenesis, underscoring its potential as a promising therapeutic target to combat obesity.
Project description:Background: Uncoupling protein 1 (UCP1) is a proton uncoupler located across the mitochondrial membrane generally involved in thermogenesis of brown adipose tissues. Although UCP1 is known to be strongly expressed in brown adipocytes, recent evidence suggest that white adipocytes can also express UCP1 under certain circumstances such as cold- or β-adrenergic receptor-stimulation, allowing them to acquire brown adipocyte-like features thereby becoming 'beige' adipocytes. Results: In this study, we report that UCP1 can be expressed in adipose-tissue macrophages (ATM) lacking functional hypoxia-inducible factor-1 (HIF-1) and this does not require cold- nor β-adrenergic receptor activation. By using myeloid-specific Hif-1α knockout (KO) mice, we observed that these mice were protected from diet-induced obesity and exhibited an improved thermogenic tolerance upon cold challenge. ATM isolated from white adipose tissues (WAT) of these mice fed with high fat diet exhibited significantly higher M2-polarization, decreased glycolysis, increased mitochondrial functions and acetyl-CoA levels, along with increased expression of Ucp1, peroxisome proliferator activated receptor-gamma co-activator-1a, and others involved in histone acetylation. Consistent with the increased Ucp1 gene expression, these ATM produced a significant amount of heat mediating lipolysis of co-cultured adipocytes liberating free fatty acid. Treating ATM with acetate, a substrate for acetyl-CoA synthesis was able to boost the heat production in wild-type or Hif-1α-deficient but not UCP1-deficient macrophages, indicating that UCP1 was necessary for the heat production in macrophages. Lastly, we observed a significant inverse correlation between the number of UCP1-expressing ATM in WAT and the body mass index of human individuals. Conclusions: UCP1-expressing ATM produce the heat to mediate lipolysis of adipocytes, indicating that this can be a novel strategy to treat and prevent diet-induced obesity.
Project description: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:Macrophage-mediated inflammatory response has been implicated in the pathogenesis of obesity and insulin resistance. Brd4 has emerged as a key regulator in the innate immune response. However, the role of Brd4 in obesity-associated inflammation and insulin resistance remains uncharacterized. Here, we demonstrated that myeloid-lineage specific Brd4 knockout (Brd4-CKO) mice were protected from high-fat-diet (HFD)-induced obesity with less fat accumulation, higher energy expenditure, and increased lipolysis in adipose tissue. Brd4-CKO mice also displayed reduced local and systemic inflammation with improved insulin sensitivity upon HFD. RNA-sequencing of adipose tissue macrophages (ATMs) from HFD-fed wide-type and Brd4-CKO mice revealed that expression of antilipolytic factor Gdf3 was significantly decreased in ATMs of Brd4-CKO mice. We also found that Brd4 bound to the promoter and enhancers of Gdf3 to facilitate PPARγ-dependent Gdf3 expression in macrophages. Furthermore, Brd4-mediated expression of Gdf3 acted as a paracrine signal targeting adipocytes to suppress the expression of lipases and the associated lipolysis in cultured cells and mice. Controlling the expression of Gdf3 in ATMs could be one of the mechanisms by which Brd4 modulates lipid metabolism and diet-induced obesity. This study suggests that Brd4 could be a potential therapeutic target for obesity and insulin resistance.
Project description:This SuperSeries is composed of the following subset Series: GSE25401: Adipose Tissue MicroRNAs as Regulators of CCL2 Production in Human Obesity [gene expression] GSE25470: Adipose Tissue MicroRNAs as Regulators of CCL2 Production in Human Obesity [miRNA data] GSE25910: Adipose Tissue MicroRNAs as Regulators of CCL2 Production in Human Obesity [differentiation data] Refer to individual Series
Project description:Obesity is defined as abnormal or excessive fat accumulation of body fat and contributes to several metabolic disorders. White adipose tissue (WAT) stores energy in the form of triglycerides and releases energy as free fatty acids and glycerol through a process called lipolysis. People with obesity have impaired catecholamine-stimulated lipolysis, but comprehensive understanding of this lipolysis is still unclear. WW domain-containing E3 ubiquitin ligase 1 (WWP1) is a member of the HECT-type E3 family of ubiquitin ligases and is associated with several diseases. We previously showed that WWP1 expression was increased in WAT of obese mice. In this study, we investigated the function of WWP1 in WAT of obese mice by analyzing the phenotype of Wwp1 knockout (KO) mice fed a high-fat diet. The mRNA levels of beta-3 adrenergic receptor (Adrb3), which were decreased with a high-fat diet, were increased by Wwp1 KO in WAT. Moreover, Wwp1 KO mice showed increased phosphorylated hormone-sensitive lipase levels in WAT and plasma non-esterified fatty acid concentrations. In contrast, noradrenaline and its metabolism were not altered in WAT of obese Wwp1 KO mice. These findings indicate that WWP1, which is increased in adipocytes because of obesity, is a candidate for suppressing the Adrb3 signaling pathway and lipolysis independently of noradrenaline metabolism.
Project description:This project includes proteomic data of brown adipose tissue from high-fat diet-induced obese mice versus wild-type mice. WTB reprents the brown adipose tissue from wild-type mice.DIOB reprents the brown adipose tissue from diet-induced obesity mice.
Project description:This project includes proteomic data of inguinal white adipose tissue from high-fat diet-induced obese mice versus wild-type mice. WTi reprents the inguinal white adipose tissue from wild-type mice.DIOi reprents the inguinal white adipose tissue from diet-induced obesity mice.