Expression Of Uncoupling Protein Research Articles

Bisphenol A and its metabolites promote white adipogenesis and impair brown adipogenesis in vitro

Bisphenol A (BPA), an obesogen, can disrupt adipogenesis in vitro, but these studies did not distinguish adipocytes as white or brown. BPA can be metabolized into BPA-glucuronide (BPA-G) and BPA-sulfate (BPA-S). These metabolites are not completely inactive in the body, but the related studies remain limited. In this study, preadipocytes isolated from mouse white and brown adipose tissues were treated with 0.1, 1, and 10μM of BPA and its metabolites for 6 days, which are equivalent to the exposure level of general and occupational populations, to investigate and compare the effects of BPA and its metabolites on white and brown adipogenesis. The results showed that BPA and BPA-G increased lipid accumulation during white adipogenesis, whereas only BPA induced this same effect during brown adipogenesis. Moreover, BPA and its metabolites upregulated the expression of pan-adipogenic markers, such as peroxisome proliferator-activated receptor gamma (PPARγ), during white adipogenesis, whereas they downregulated that of PPARγ during brown adipogenesis. Additionally, BPA also inhibited the mRNA and protein expression of brown fat-specific markers (e.g., PPARγ coactivator 1-1alpha (PGC1-α) and uncoupling protein 1 (UCP1)), and mitochondrial activity during brown adipogenesis, and BPA-G also reduced the mRNA expression levels of Pgc1-α and Ucp1. These findings indicated that BPA induced different effects on white and brown adipogenesis, enhancing the former and hindering the latter. Despite less potent than BPA, BPA-G and BPA-S might also affect white and brown adipogenesis. This research provides in-depth insights into the obesogenic effects of BPA and the biological activities of its metabolites.

Hepatic SerpinA1 improves energy and glucose metabolism through regulation of preadipocyte proliferation and UCP1 expression.

Lipodystrophy and obesity are associated with insulin resistance and metabolic syndrome accompanied by fat tissue dysregulation. Here, we show that serine protease inhibitor A1 (SerpinA1) expression in the liver is increased during recovery from lipodystrophy caused by the adipocyte-specific loss of insulin signaling in mice. SerpinA1 induces the proliferation of white and brown preadipocytes and increases the expression of uncoupling protein 1 (UCP1) to promote mitochondrial activation in mature white and brown adipocytes. Liver-specific SerpinA1 transgenic mice exhibit increased browning of adipose tissues, leading to increased energy expenditure, reduced adiposity and improved glucose tolerance. Conversely, SerpinA1 knockout mice exhibit decreased adipocyte mitochondrial function, impaired thermogenesis, obesity, and systemic insulin resistance. SerpinA1 forms a complex with the Eph receptor B2 and regulates its downstream signaling in adipocytes. These results demonstrate that SerpinA1 is an important hepatokine that improves obesity, energy expenditure and glucose metabolism by promoting preadipocyte proliferation and activating mitochondrial UCP1 expression in adipocytes.

Abstract 4140191: ChREBP Drives Brown Adipocyte Differentiation and Lipid Utilization for Excess Energy Expenditure

Introduction: Although several anti-obesity drugs have become recently available, they reduce patients’ appetite, which might worsen cardiovascular disease (CVD) prognosis by malnutrition/cachexia. Brown adipose tissue (BAT) oxidizes glucose and lipids for thermogenesis, a process that requires excess energy expenditure provided by uncoupling protein 1 (UCP1) + cells. Recently, critical roles of BAT in cardio-protection have been discovered. Taken together, boosting BAT activity can be a novel anti-obesity treatment suitable for CVD patients. In this study, we aimed to establish anti-obesity strategy by manipulation of the glucose-sensing lipid-storage transcription factor, ChREBP, with unexpected function of boosting lipid utilization in BAT. Methods and Results: Through mouse/human single-cell/nucleus RNA sequencing analyses, we identified ChREBP as specifically expressed in highly thermogenic UCP1 + brown adipocytes ( Fig.A ). To investigate the role of ChREBP in BAT formation, we generated human brown adipocyte-like model from induced pluripotent stem cells (iPSC-BAT, Fig.B ). The iPSC-BAT exhibited high UCP1 and ChREBP expression, multi-locular lipid droplets, and vigorous oxygen consumption. Knocking down ChREBP strongly blocked iPSC-BAT differentiation ( Fig.C ) and impaired lipid utilization ( Fig.D ). Consistently, in vitro deletion of ChREBP in mouse BAT progenitors impeded differentiation, lipid droplet accumulation, and oxygen consumption ( Fig.E-F ). In vivo, BAT-specific deletion of all ChREBP isoforms reduced lipid accumulation and BAT characteristics. Conversely, using a new mouse model for Cre-mediated ChREBPβ overexpression, we showed that ChREBPβ overexpression in BAT (Chβ BATOX) increased BAT cellularity and activated lipogenic machineries, with paradoxical decreased lipid content, suggesting excessively activated lipid consumption in BAT ( Fig.G ). More importantly, Chβ BATOX maintained UCP1 expression and reduced fat volume ( Fig.H ) even after strongly inhibiting BAT activity. Conclusion: In summary, ChREBP is essential for BAT development and thermogenic capacity by affecting lipid utilization. Our results suggest that ChREBPβ activation may be a novel anti-obesity avenue for CVD patients.

Intermittent Fasting Improves Insulin Resistance by Modulating the Gut Microbiota and Bile Acid Metabolism in Diet-Induced Obesity.

Adipose tissue macrophages (ATMs) are crucial in the pathogenesis of insulin resistance (IR). Intermittent fasting (IF) is an effective intervention for obesity. However, the underlying mechanism by which IF improves IR remains unclear. Male C57BL/6J mice are fed chow-diet and high-fat diet (HFD) for 12 weeks, then is randomized into ad libitum feeding or every other day fasting for 8 weeks. Markers of ATMs and expression of uncoupling protein 1 (UCP-1) are determined. Gut microbiota and bile acids (BAs) are profiled using 16S rRNA sequencing and targeted metabolomics analysis. Results indicate that IF improves IR in HFD-induced obesity. IF decreases ATM infiltration, pro-inflammatory M1 gene expression, and promotes white adipose tissue (WAT) browning by elevating UCP-1 expression. IF restructures microbiota composition, significantly expanding the abundance of Verrucomicrobia particularly Akkermansia muciniphila, with the decrease of that of Firmicutes. IF increases the level of total BAs and alters the composition of BAs with higher proportion of 12α-hydroxylated (12α-OH) BAs. The changes in these BAs are correlated with differential bacteria. The findings indicate that IF improves IR partially mediated by the interplay between restructured gut microbiota and BAs metabolism, which has implications for the dietary management in obesity.

USP2 Mitigates Reactive Oxygen Species-Induced Mitochondrial Damage via UCP2 Expression in Myoblasts

Ubiquitin-specific protease 2 (USP2) maintains mitochondrial integrity in culture myoblasts. In this study, we investigated the molecular mechanisms underlying the protective role of USP2 in mitochondria. The knockout (KO) of the Usp2 gene or the chemical inhibition of USP2 induced a robust accumulation of mitochondrial reactive oxygen species (ROS), accompanied by defects in mitochondrial membrane potential, in C2C12 myoblasts. ROS removal by N-acetyl-L-cysteine restored the mitochondrial dysfunction induced by USP2 deficiency. Comprehensive RT-qPCR screening and following protein analysis indicated that both the genetic and chemical inhibition of USP2 elicited a decrease in uncoupling protein 2 (UCP2) at mRNA and protein levels. Accordingly, the introduction of a Ucp2-expressing construct effectively recovered the mitochondrial membrane potential, entailing an increment in the intracellular ATP level in Usp2KO C2C12 cells. In contrast, USP2 deficiency also decreased peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) protein in C2C12 cells, while it upregulated Ppargc1a mRNA. Overexpression studies indicated that USP2 potentially stabilizes PGC1α in an isopeptidase-dependent manner. Given that PGC1α is an inducer of UCP2 in C2C12 cells, USP2 might ameliorate mitochondrial ROS by maintaining the PGC1α–UCP2 axis in myoblasts.

Repurposed genipin targeting UCP2 exhibits antitumor activity through inducing ferroptosis in glioblastoma.

Uncoupling protein-2 (UCP2) controls the antioxidant response and redox homeostasis in cancer and is considered a potent molecular target for cancer treatment. However, the specific mechanism of UCP2 inhibition and its role in glioblastoma (GBM) have not yet been elucidated. Here, we attempt to identify a UCP2 inhibitor and study the underlying molecular mechanism in GBM. Bioinformatics analysis and immunohistochemistry are used to validate the high expression of UCP2 in GBM and its prognostic significance. Drug intervention and tumor xenograft experiments are conducted to determine the inhibitory effect of genipin, a UCP2 inhibitor, on UCP2. The mitochondrial membrane potential and key ferroptosis genes are examined to determine the occurrence of ferroptosis. High expression of UCP2 in GBM is associated with poor prognosis, and inhibiting UCP2 can alleviate the malignant behavior of GBM tumors. Genipin can downregulate the expression of GPX4 and upregulate the expression of ACSL4 by inhibiting UCP2, leading to ferroptosis and alleviating the malignant behavior of tumors. In summary, UCP2 is a potential therapeutic target for GBM. Genipin, which targets UCP2, effectively inhibits GBM development by inducing ferroptosis in vivo and in vitro. These findings indicate that genipin treatment based on UCP2 targeting has potential therapeutic applications with a clinical perspective for the treatment of GBM patients.

A Comprehensive Pan-Cancer Analysis of the Mitochondrial Uncoupling Protein UCP2, with a Focus on Sex and Gender-Related Aspects.

Mitochondrial uncoupling protein 2 (UCP2) plays a crucial role in regulating oxidative stress and cellular metabolism, positioning it as an important subject in oncological research. The involvement of UCP2 in cancer is complex and context-dependent, suggesting it as a potential therapeutic target. In this study, we aimed to perform a comprehensive pan-cancer analysis of UCP2, with a particular focus on gender-related malignancies such as breast (BRCA), prostate (PRAD), ovarian (OV), and testicular tumors (TGCT). We analyzed UCP2 expression in The Cancer Genome Atlas (TCGA), examining correlations with prognosis, tumor mutational burden (TMB), microsatellite instability (MSI), immune cell infiltration, immune checkpoint genes, genes involved in steroidogenesis, sex hormone receptor genes, and drug sensitivity. Significant variability in UCP2 expression was observed across cancer types. UCP2 levels were elevated in BRCA and OV but reduced in PRAD and TGCT. High UCP2 expression was associated with a better prognosis in OV and poorer overall survival in PRAD. Furthermore, UCP2 correlated with TMB and MSI in OV, TGCT, and BRCA. UCP2 expression was also linked to immune cell infiltration, immune checkpoint genes, steroidogenic genes, and sex hormone receptor genes, with variable effects depending on cancer type and gender. Additionally, UCP2 also demonstrated sensitivity to specific anticancer drugs. Our findings highlight the interplay between UCP2, immune and hormonal pathways, and drug responseand reveal potential opportunities for new therapeutic combinations, especially in gender-related cancers.

HuR-dependent expression of RyR2 contributes to calcium-mediated thermogenesis in brown adipocytes.

Several uncoupling protein 1 (UCP1)-independent thermogenic pathways have been described in thermogenic adipose tissue, including calcium-mediated thermogenesis in beige adipocytes via sarco/endoplasmic reticulum ATPase (SERCA). We have previously shown that adipocyte-specific deletion of the RNA binding protein human antigen R (HuR) results in thermogenic dysfunction independent of UCP1 expression. RNA sequencing revealed the downregulation of several genes involved in calcium ion transport upon HuR deletion. The goal of this work was to define the HuR-dependent mechanisms of calcium driven thermogenesis in brown adipocytes. We generated (BAT)-specific HuR-deletion (BAT-HuR -/- ) mice and show that their body weight, glucose tolerance, brown and white adipose tissue weights, and total lipid droplet size were not significantly different compared to wild-type. Similar to our initial findings in Adipo-HuR -/- mice, mice with BAT-specific HuR deletion are cold intolerant following acute thermal challenge at 4°C, demonstrating specificity of acute HuR-dependent thermogenesis to BAT. We also found decreased expression of ryanodine receptor 2 (RyR2), but no changes in RyR2, SERCA1, SERCA2, or UCP1 expression, in BAT from BAT-HuR -/- mice. Next, we used Fluo-4 calcium indicator dye to show that genetic deletion or pharmacological inhibition of HuR blunts the increase in cytosolic calcium concentration in SVF-derived primary brown adipocytes. Moreover, we saw a similar blunting in β-adrenergic-mediated heat generation, as assessed by ERtherm AC fluorescence, in SVF-derived brown adipocytes following HuR inhibition or deletion. Mechanistically, we show that HuR directly binds and reduces the decay rate of RyR2 mRNA in brown adipocytes, and stabilization of RyR2 via S107 rescues β-adrenergic-mediated cytosolic calcium increase and heat generation in HuR deficient brown adipocytes. In conclusion, our results suggest that HuR-dependent control of RyR2 expression plays a significant role in the thermogenic function of brown adipose tissue through modulation of SR calcium cycling.

Expression of PGC-1α, PPAR-α and UCP1 genes, metabolic and anthropometric factors in response to sodium butyrate supplementation in patients with obesity: a triple-blind, randomized placebo-controlled clinical trial.

There is increasing evidence that gut metabolites have a role in the etiology of obesity. This study aimed to investigate the effects of sodium butyrate (NaB) supplementation on the expression of peroxisome proliferator-activated receptor (PPAR) gamma coactivator-1α (PGC-1α), PPAR-α, and uncoupling protein-1 (UCP-1) genes, as well as on the metabolic parameters and anthropometric indices in persons with obesity. In this triple-blind placebo-controlled randomized clinical trial, 50 individuals with obesity were randomly assigned to NaB (600 mg/day) + hypo-caloric diet or placebo group + hypo-caloric diet for 8 weeks. The study measured the participants' anthropometric characteristics, food consumption, and feelings of hunger in addition to the serum levels of metabolic indices and the mRNA expression of the PGC-1α, PPAR-α, and UCP-1 genes in peripheral blood mononuclear cells (PBMCs). PGC-1α and UCP-1 genes expression significantly increased in NaB group compared to the placebo at the endpoint. A significant decrease in weight, BMI, and waist circumference (WC) was observed in NaB group. Among the metabolic factors, NaB significantly decreased fasting blood sugar (FBS) (P = 0.04), low-density lipoprotein cholesterol (LDL-C) (P = 0.038) and increased high-density lipoprotein cholesterol (HDL-C) (P = 0.016). NaB could not significantly change serum GLP-1 level. This study unveiled NaB supplementation alone cannot have significant beneficial effects on anthropometric, and biochemical factors. NaB could affect anthropometric and metabolic risk variables associated with obesity only when prescribed, along with calorie restriction. This study was registered in the Iranian Registry of Clinical Trials ( https://en.irct.ir/trial/53968 ) on 31 January 2021 (registry number IRCT20190303042905N2).

Gut microbiota is involved in leptin-induced thermoregulation in Mongolian gerbil (Meriones unguiculatus).

Leptin is a hormone that secreted by adipocytes and may promote energy expenditure by increasing thermogenesis. Our previous studies have shown that thermo-transient receptor potentials (thermo-TRPs) and gut microbiota are associated with thermoregulation in Mongolian gerbils, which are characterized by relative high serum leptin concentrations. Here, we test whether leptin can stimulate non-shivering thermogenesis (NST) in Mongolian gerbils, and whether thermo-TRPs and gut microbiota are involved in leptin-induced thermogenesis. First, gerbils were given acute leptin treatment (ALT) with different doses. Results showed that ALT significantly increased the body temperature of gerbils and change the composition of gut microbiota. Moreover, ALT groups showed a trend towards increased expression of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT). Then, we investigated the effect of chronic leptin treatment (CLT) on gerbils. Surprisingly, CLT did not affect gerbils' food intake and body weight, but it significantly increased the body temperature at the end. Besides, CLT did not affect the expression of thermogenic markers in BAT, white adipose tissue (WAT) and skeletal muscle. However, CLT increased the expression of leptin receptors and TRPV2 in the small intestine and affected the composition of gut microbiota. Together, our data suggest leptin may increase body temperature by regulating gut microbiota. In conclusion, the Mongolian gerbils with serum hyperleptin is beneficial for adapting the cold living environments, and TRPV2 and gut microbiota are involved.

CAMP driven UCP1 induction in human adipocytes requires ATGL-catalyzed lipolysis

ObjectiveThe uncoupling protein 1 (UCP1) is induced in brown or “beige” adipocytes through catecholamine-induced cAMP signaling, which activates diverse transcription factors. UCP1 expression can also be enhanced by PPARγ agonists such as rosiglitazone (Rsg). However, it is unclear whether this upregulation results from de-novo differentiation of beige adipocytes from progenitor cells, or from the induction of UCP1 in pre-existing adipocytes. To explore this, we employed human adipocytes differentiated from progenitor cells and examined their acute response to Rsg, to the adenylate-cyclase activator forskolin (Fsk), or to both simultaneously. MethodsAdipocytes generated from primary human progenitor cells were differentiated without exposure to PPARγ agonists, and treated for 3, 6 or 78 h to Fsk, to Rsg, or to both simultaneously. Bulk RNASeq, RNAScope, RT-PCR, CRISPR-Cas9 mediated knockout, oxygen consumption and western blotting were used to assess cellular responses. ResultsUCP1 mRNA expression was induced within 3 h of exposure to either Rsg or Fsk, indicating that Rsg’s effect is independent on additional adipocyte differentiation. Although Rsg and Fsk induced distinct overall transcriptional responses, both induced genes associated with calcium metabolism, lipid droplet assembly, and mitochondrial remodeling, denoting core features of human adipocyte beiging. Unexpectedly, we found that Fsk-induced UCP1 expression was reduced by approximately 80% following CRISPR-Cas9-mediated knockout of PNPLA2, the gene encoding the triglyceride lipase ATGL. As anticipated, ATGL knockout suppressed lipolysis; however, the associated suppression of UCP1 induction indicates that maximal cAMP-mediated UCP1 induction requires products of ATGL-catalyzed lipolysis. Supporting this, we observed that the reduction in Fsk-stimulated UCP1 induction caused by ATGL knockout was reversed by Rsg, implying that the role of lipolysis in this process is to generate natural PPARγ agonists. ConclusionsUCP1 transcription is known to be stimulated by transcription factors activated downstream of cAMP-dependent protein kinases. Here we demonstrate that UCP1 transcription can also be acutely induced through PPARγ-activation. Moreover, both pathways are activated in human adipocytes in response to cAMP, synergistically inducing UCP1 expression. The stimulation of PPARγ in response to cAMP may result from the production of natural PPARγ activating ligands through ATGL-mediated lipolysis.

A pectic polysaccharide from Typhonii Rhizoma: Characterization and antiproliferative activity in K562 cells through regulating mitochondrial function and energy metabolism

The pectic polysaccharide WTRP-A0.2b (43 kDa) has been isolated from Typhonii rhizoma and analyzed in terms of its structural features, anti-tumor activities and mechanism of action. NMR, FT-IR, monosaccharide composition, and enzymology demonstrate that WTRP-A0.2b is composed of rhamnogalacturonan I (RG-I), rhamnogalacturonan II (RG-II) and homogalacturonan (HG) domains with mass ratios of 3.7:1:1.7, respectively. The RG-I domains contain a highly branched structure that is substituted primarily with β-D-1,4-galactan, α-L-1,5-arabinan, and AG-II. The HG domains contain un-esterified and methyl-esterified and/or acetyl-esterified oligogalacturonides with a degree of polymerization of 1–8. In vitro experiments demonstrate that WTRP-A0.2b inhibits proliferation of K562 cells by inducing mitochondrial damage and suppressing glycolysis. This activity promotes mitochondrial permeability, increases production of reactive oxygen species (ROS), boosts extracellular oxygen consumption and adenosine triphosphate (ATP) content, while it decreases uncoupling protein-2 (UCP2) expression and lactic acid content. Our results provide valuable insight for screening natural polysaccharide-based anti-tumor effects of polysaccharides from Typhonii rhizoma.

Fas (CD95) expression in adipocytes contributes to diet-induced obesity.

Induction of browning in white adipose tissue (WAT) increases energy expenditure and may be an attractive target for the treatment of obesity. Since activation of Fas (CD95) induces pathways known to blunt expression of uncoupling protein 1 (UCP1), we hypothesized that Fas expression in adipocytes inhibits WAT browning and thus contributes to the development of obesity. Adipocyte-specific Fas knockout (FasΔadipo) and control littermate (FasF/F) mice were fed a regular chow diet or a high-fat diet (HFD) for 20 weeks. Energy expenditure was assessed by indirect calorimetry, and browning was determined in subcutaneous WAT. In vitro, UCP1 was analyzed in subcutaneous murine adipocytes treated with or without Fas ligand. Moreover, FAS expression in WAT was correlated to UCP1 and percentage of body fat in human individuals. HFD-fed FasΔadipo mice displayed reduced body weight gain and blunted adiposity compared to control littermates. Concomitantly, whole-body energy expenditure and WAT browning were elevated. In cultured adipocytes, Fas ligand treatment blunted isoproterenol-induced UCP1 protein levels. In support of these findings in rodents, FAS expression in WAT correlated negatively with UCP1 but positively with adiposity in human individuals. Fas activation in adipocytes contributes to HFD-associated adiposity in rodents and may be a therapeutic target to reduce obesity and associated diseases.

Myricetin and myricitrin indirectly and directly increases uncoupling protein-1 mRNA expression in C3H10T1/2 beige adipocytes

In thermogenic brown and beige adipocytes, the proton gradient formed by energy derived from nutrients such as lipids and carbohydrates is consumed by uncoupling protein-1 (UCP-1), resulting in thermogenesis without ATP production in the mitochondria. Accordingly, increased UCP-1 expression represents a crucial aspect of dietary management for individuals with overweight and obesity. Myricetin and its glycoside, myricitrin, are food-derived flavonoids that possess various beneficial effects. This is the first study to examine the effects of myricetin and myricitrin on the inflammation-inhibited expression of Ucp-1 using a modified cell-based assay with conditioned medium (CM). The CM derived from lipopolysaccharide (LPS)-activated RAW264.7 macrophages was observed to inhibit the Ucp-1 expression induced by adrenergic stimulation in 10T1/2 adipocytes. Conversely, the CM derived from activated macrophages treated with myricetin or myricitrin reversed this inhibition of Ucp-1 expression. Subsequently, the direct effects of both the compounds on basal and adrenaline-induced expression of Ucp-1 were investigated. In contrast to a previous report, myricetin and myricitrin did not increase the basal Ucp-1 mRNA expression in 10T1/2 adipocytes when treated during the differentiation-promoting period. However, we have found for the first time that both compounds enhanced the adrenergic sensitivity of 10T1/2 adipocytes when treated during the differentiation-inducing period. These results indicate that myricetin and myricitrin have indirect effects on inflammation-induced suppression and direct effects on adrenergic sensitivity, suggesting a novel mechanism that both compounds increase Ucp-1 expression in vivo by both indirect and direct effects, rather than by affecting basal expression.

Keys to the switch of fat burning: stimuli that trigger the uncoupling protein 1 (UCP1) activation in adipose tissue.

As one of the main pathogenic factors of cardiovascular and cerebrovascular diseases, the incidence of metabolic diseases such as adiposity and metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing annually. It is urgent and crucial to find more therapeutic targets to treat these diseases. Mainly expressed in brown adipocytes, mitochondrial uncoupling protein 1 (UCP1) is key to the thermogenesis of classical brown adipose tissue (BAT). Furthermore, white adipose tissue (WAT) is likely to express more UCP1 and subsequently acquire the ability to undergo thermogenesis under certain stimuli. Therefore, targeting and activating UCP1 to promote increased BAT thermogenesis and browning of WAT are helpful in treating metabolic diseases, such as adiposity and MASLD. In this case, the stimuli that activate UCP1 are emerging. Therefore, we summarize the thermogenic stimuli that have activated UCP1 in recent decades, among which cold exposure is one of the stimuli first discovered to activate BAT thermogenesis. As a convenient and efficient therapy with few side effects and good metabolic benefits, physical exercise can also activate the expression of UCP1 in adipose tissue. Notably, for the first time, we have summarized and demonstrated the stimuli of traditional Chinese medicines that can activate UCP1, such as acupuncture, Chinese herbal formulas, and Chinese medicinal herbs. Moreover, pharmacological agents, functional foods, food ingredients, and the gut microbiota are also commonly associated with regulating and activating UCP1. The identification and analysis of UCP1 stimuli can greatly facilitate our understanding of adipose tissue thermogenesis, including the browning of WAT. Thus, it is more conducive to further research and therapy for glucose and lipid metabolism disorders.

CPEB2-activated Prdm16 translation promotes brown adipocyte function and prevents obesity

ObjectiveBrown adipose tissue (BAT) plays an important role in mammalian thermogenesis through the expression of uncoupling protein 1 (UCP1). Our previous study identified cytoplasmic polyadenylation element binding protein 2 (CPEB2) as a key regulator that activates the translation of Ucp1 with a long 3′-untranslated region (Ucp1L) in response to adrenergic signaling. Mice lacking CPEB2 or Ucp1L exhibited reduced UCP1 expression and impaired thermogenesis; however, only CPEB2-null mice displayed obesogenic phenotypes. Hence, this study aims to investigate how CPEB2-controlled translation impacts body weight. MethodsBody weight measurements were conducted on mice with global knockout (KO) of CPEB2, UCP1 or Ucp1L, as well as those with conditional knockout of CPEB2 in neurons or adipose tissues. RNA sequencing coupled with bioinformatics analysis was used to identify dysregulated gene expression in CPEB2-deficient BAT. The role of CPEB2 in regulating PRD1-BF1-RIZ1 homologous-domain containing 16 (PRDM16) expression was subsequently confirmed by RT-qPCR, Western blotting, polysomal profiling and luciferase reporter assays. Adeno-associated viruses (AAV) expressing CPEB2 or PRDM16 were delivered into BAT to assess their efficacy in mitigating weight gain in CPEB2-KO mice. ResultsWe validated that defective BAT function contributed to the increased weight gain in CPEB2-KO mice. Transcriptomic profiling revealed upregulated expression of genes associated with muscle development in CPEB2-KO BAT. Given that both brown adipocytes and myocytes stem from myogenic factor 5-expressing precursors, with their cell-fate differentiation regulated by PRDM16, we identified that Prdm16 was translationally upregulated by CPEB2. Ectopic expression of PRDM16 in CPEB2-deprived BAT restored gene expression profiles and decreased weight gain in CPEB2-KO mice. ConclusionsIn addition to Ucp1L, activation of Prdm16 translation by CPEB2 is critical for sustaining brown adipocyte function. These findings unveil a new layer of post-transcriptional regulation governed by CPEB2, fine-tuning thermogenic and metabolic activities of brown adipocytes to control body weight.

Maid gene dysfunction promotes hyperobesity via the reduction of adipose tissue inflammation in Mc4r gene-deficient mice

The onset and progression mechanisms of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) are being studied. We developed and analyzed a new mouse model of obesity by combining maternal Id-like molecule (Maid) and melanocortin-4 receptor (Mc4r) gene deletions. Four mice, each at 12 and 28 weeks of age, were analyzed for each genotype: Maid gene knockout, Mc4r gene knockout, combined Mc4r and Maid gene knockout, and Mc4r gene knockout with a high-fat diet. Mice with a combined deficiency of Mc4r and Maid gene showed significantly more severe obesity compared to all other genotypes, but no liver fibrosis or a decline in metabolic status were observed. In visceral white adipose tissue, Maid and Mc4r gene knockout mice had fewer CD11c-positive cells and lower mRNA expression of both inflammatory and anti-inflammatory cytokines. Furthermore, Maid and Mc4r gene knockout mice showed lower expression of adipocytokines in visceral white adipose tissue and uncoupling protein-1 in scapular brown adipose tissue. The expression of adipocytokines and uncoupling protein-1 is regulated by sympathetic nerve signaling that contribute severe obesity in Maid and Mc4r gene knockout mice. These mechanisms contribute hyperobesity in Maid and Mc4r gene knockout mice.

Regulatory Roles of Long Non-Coding RNAs in Arterial Stiffness and Hypertension: Insights from Two African American Studies.

Arterial stiffness, commonly assessed via pulse wave velocity (PWV), is marked by reduced arterial elasticity and serves as a significant risk factor for cardiovascular disease and an early indicator of hypertension. This study investigated the regulatory roles of long non-coding RNAs (lncRNAs) in modulating mRNAs associated with arterial stiffness and hypertension, with a particular focus on African Americans, a population disproportionately impacted by hypertension. We utilized whole-blood transcriptome sequencing data from two African American (AA) cohorts with high hypertension prevalence: the GENE-FORECAST study (436 subjects) and the MH-GRID study (179 subjects). Our objectives were to: (1) identify lncRNAs and mRNAs differentially expressed (DE) between the upper and lower tertiles of PWV, (2) determine DE lncRNAs associated with the expression levels of each DE mRNA, and (3) link the lncRNA-modulated mRNAs to hypertension across both datasets. Differential expression analysis revealed 1,035 DE mRNAs and 31 DE lncRNAs between upper and lower PWV groups. Then lncRNA-mRNA pairs significantly associated were identified, involving 31 unique lncRNAs and 1,034 unique mRNAs. Finally, 22 of the lncRNA-modulated mRNAs initially linked to PWV were found associated with hypertension, in both datasets. Interestingly, 30 lncRNAs were linked to the expression of UCP2 (Uncoupling Protein 2), a gene implicated in oxidative stress and endothelial function. Our findings underscore the significant roles of lncRNAs in regulating gene expression associated with arterial stiffness and hypertension. The differential expression of UCP2 in relation to PWV and hypertension, along with its potential regulation by lncRNAs, offers valuable insights into the molecular mechanisms underlying arterial stiffness and its connection with hypertension.

PPARγ activation by lipolysis-generated ligands is required for cAMP dependent UCP1 induction in human thermogenic adipocytes.

The uncoupling protein 1 (UCP1) is induced in brown or "beige" adipocytes through catecholamine-induced cAMP signaling, which activates diverse transcription factors. UCP1 expression can also be enhanced by PPARγ agonists such as rosiglitazone (Rsg). However, it is unclear whether this upregulation results from de-novo differentiation of beige adipocytes from progenitor cells, or from the induction of UCP1 in pre-existing adipocytes. To explore this, we employed human adipocytes differentiated from progenitor cells and examined their acute response to Rsg, to the adenylate-cyclase activator forskolin (Fsk), or to both simultaneously. Adipocytes generated from primary human progenitor cells were differentiated without exposure to PPARγ agonists, and treated for 3, 6 or 78 hours to Fsk, to Rsg, or to both simultaneously. Bulk RNASeq, RNAScope, RT-PCR, CRISPR-Cas9 mediated knockout, oxygen consumption and western blotting were used to assess cellular responses. UCP1 mRNA expression was induced within 3 hours of exposure to either Rsg or Fsk, indicating that Rsg's effect is independent on additional adipocyte differentiation. Although Rsg and Fsk induced distinct overall transcriptional responses, both induced genes associated with calcium metabolism, lipid droplet assembly, and mitochondrial remodeling, denoting core features of human adipocyte beiging. Unexpectedly, we found that Fsk-induced UCP1 expression was reduced by approximately 80% following CRISPR-Cas9-mediated knockout of PNPLA2 , the gene encoding the triglyceride lipase ATGL. As anticipated, ATGL knockout suppressed lipolysis; however, the associated suppression of UCP1 induction indicates that maximal cAMP-mediated UCP1 induction requires products of ATGL-catalyzed lipolysis. Supporting this, we observed that the reduction in Fsk-stimulated UCP1 induction caused by ATGL knockout was reversed by Rsg, implying that the role of lipolysis in this process is to generate natural PPARγ agonists. UCP1 transcription is known to be stimulated by transcription factors activated downstream of cAMP-dependent protein kinases. Here we demonstrate that UCP1 transcription can also be acutely induced through PPARγ-activation. Moreover, both pathways are activated in human adipocytes in response to cAMP, synergistically inducing UCP1 expression. The stimulation of PPARγ in response to cAMP occurs as a result of the production of natural PPARγ activating ligands through ATGL-mediated lipolysis.

A Mixture of Lactobacillus HY7601 and KY1032 Regulates Energy Metabolism in Adipose Tissue and Improves Cholesterol Disposal in High-Fat-Diet-Fed Mice.

We aimed to characterize the anti-obesity and anti-atherosclerosis effects of Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032 using high-fat diet (HFD)-fed obese C57BL/6 mice. We divided the mice into control (CON), HFD, HFD with 108 CFU/kg/day probiotics (HFD + KL, HY7301:KY1032 = 1:1), and HFD with 109 CFU/kg/day probiotics (HFD + KH, HY7301:KY1032 = 1:1) groups and fed/treated them during 7 weeks. The body mass, brown adipose tissue (BAT), inguinal white adipose tissue (iWAT), and epididymal white adipose tissue (eWAT) masses and the total cholesterol and triglyceride concentrations were remarkably lower in probiotic-treated groups than in the HFD group in a dose-dependent manner. In addition, the expression of uncoupling protein 1 in the BAT, iWAT, and eWAT was significantly higher in probiotic-treated HFD mice than in the HFD mice, as demonstrated by immunofluorescence staining and Western blotting. We also measured the expression of cholesterol transport genes in the liver and jejunum and found that the expression of those encoding liver-X-receptor α, ATP-binding cassette transporters G5 and G8, and cholesterol 7α-hydroxylase were significantly higher in the HFD + KH mice than in the HFD mice. Thus, a Lactobacillus HY7601 and KY1032 mixture with 109 CFU/kg/day concentration can assist with body weight regulation through the management of lipid metabolism and thermogenesis.