Promote Energy Expenditure Research Articles

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

Leptin is a hormone that is 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 tested 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 changed 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 mass, but it significantly increased the body temperature at the end. Further, CLT did not affect the expression of thermogenic markers in BAT, white adipose tissue (WAT) or 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, serum hyperleptin in Mongolian gerbils is beneficial for adapting to cold environments, and TRPV2 and gut microbiota are involved.

8030 Sexually Dimorphic Metabolic Consequences Of CCN5/WISP2 Gene Deletion Revealed A Male-Specific Pattern Of Gene Expression

Abstract Disclosure: M. Yang: None. V. Xega: None. M. Zakikhani: None. J. Liu: None. Matricellular protein CCN5/WISP2 is a novel target of IGF-1 and WNT signaling within the pancreatic islets. Our previous research suggests CCN5 promotes β-cell proliferation and survival through Akt/PKB and focal adhesion kinase signaling pathways. More recently, we have reported sexual dimorphic features of CCN5 gene deletion and overexpression. Specifically, male knockout mice demonstrated improved insulin sensitivity and glucose tolerance upon high-fat diet (HFD)-induced obesity, while females were unaffected (ENDO 2022). On the other hand, male aP2-CCN5 transgenic mice that overexpress CCN5 in adipose tissues were partially protected from HFD-streptozotocin induced diabetes, with improved glucose tolerance; females exhibited impaired glucose tolerance and exacerbated diabetes (ENDO 2023). Our findings indicate that an increased level of CCN5 protects β-cells, but only in male mice. This protection cannot be solely attributed to the pro-islet effect and suggests the involvement of extra-pancreatic and sex-specific roles. This study indirectly screened normal CCN5 gene expression by detecting β-galactosidase activity, measured in X-gal-stained tissues before fixation and sectioning. In order to create the gene deletion through homologous recombination, LacZ was inserted between exons 2 and 5 of the CCN5 gene. As a result, male knockout mice exhibited a distinct blue staining in the pseudostratified columnar epithelium with stereocilia of the epididymis and vas deferens. This type of epithelium comprises a single layer of cells but appears to have multiple layers due to the nuclei being at different levels. The epithelium possesses long projections made of actin filaments and plays a crucial role in absorbing, transporting, and maturing sperm cells. The staining was also clear in Leydig cells of the testis, which produce testosterone, which was confirmed using immunohistochemistry and authentic CCN5 antibody. In female mice, however, only a few cells in the ovary and scattered staining was observed in the endometrial glands of the uterus. Since androgens promote energy expenditure, lipolysis, and insulin sensitivity, knockout or overexpression of CCN5 may potentially affect androgen and/or sperm production, leading to metabolic consequences in males. Our results from in vitro, knockout, and overexpression models support the notion that CCN5 promotes β-cell growth and survival against diabetes and further suggest that it possesses sex-specific, metabolic effects. Presentation: 6/2/2024

L-Fucose-Rich Sulfated Glycans from Edible Brown Seaweed: A Promising Functional Food for Obesity and Energy Expenditure Improvement.

The global obesity epidemic, exacerbated by the sedentary lifestyle fostered by the COVID-19 pandemic, presents a growing socioeconomic burden due to decreased physical activity and increased morbidity. Current obesity treatments show promise, but they often come with expensive medications, frequent injections, and potential side effects, with limited success in improving obesity through increased energy expenditure. This study explores the potential of a refined sulfated polysaccharide (SPSL), derived from the brown seaweed Scytosiphon lomentaria (SL), as a safe and effective anti-obesity treatment by promoting energy expenditure. Chemical characterization revealed that SPSL, rich in sulfate and L-fucose content, comprises nine distinct sulfated glycan structures. In vitro analysis demonstrated potent anti-lipogenic properties in adipocytes, mediated by the downregulation of key adipogenic modulators, including 5' adenosine monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor γ (PPARγ) pathways. Inhibiting AMPK attenuated the anti-adipogenic effects of SPSL, confirming its involvement in the mechanism of action. Furthermore, in vivo studies using zebrafish models showed that SPSL increased energy expenditure and reduced lipid accumulation. These findings collectively highlight the therapeutic potential of SPSL as a functional food ingredient for mitigating obesity-related metabolic dysregulation by promoting energy expenditure. Further mechanistic and preclinical investigations are warranted to fully elucidate its mode of action and evaluate its efficacy in obesity management, potentially offering a novel, natural therapeutic avenue for this global health concern.

Abstract P216: Distal Convoluted Tubule-Specific Deletion of Specific Deletion of (Pro)Renin Receptor in Mice Increases Energy Expenditure and Enhances Aggressiveness

Our previous study suggested a potential role of (pro)renin receptor (PRR) in the regulation of Na + -Cl - cotransporter (NCC) activity in the distal convoluted tubule (DCT). Here, we employed Slc12a3 -CreERT2 to generate inducible DCT-specific deletion of PRR in mice (KO). As expected, the KO mice exhibited a 1.8-fold increase in renal NCC activity as reflected by HCTZ-induced natriuresis. Surprisingly, the KO mice developed metabolic and behavioral phenotypes. By calorimetry, 4-month-old male KO mice exhibited an enhanced energy expenditure as compared with floxed controls (oxygen consumption: 4172.5 ± 118.0 ml/kg/hr vs. 3303.5 ± 69.8 ml/kg/hr; CO 2 consumption: 3617.3 ± 87.8 ml/kg/hr vs. 2784.2 ± 58.5 ml/kg/hr; heat production: 20.4 ± 0.6 Kcal/kg/h vs. 16.2 ± 0.8 Kcal/kg/h, n = 5-9, p < 0.01), accompanied by enhanced locomotor activity (by 41.3%) and reduced body weight (30.2 ± 0.5 g vs. 28.0 ± 0.3 g, n = 5-9, p < 0.05). The changes in locomotor activity were confirmed by using radiotelemetry. Additionally, resident-intruder aggression test demonstrated that under basal condition, the KO mice exhibited a higher aggression rate as compared with floxed controls (80% in KO group vs . 30% in floxed group, n = 10). The KO mice also exhibited shorter clinch attack latencies, higher number of attacks and attack duration (attack latencies: 79.0 ± 17.6 s in KO group vs . 172.5 ± 5.3 s in floxed group; attack frequency: 3.4 ± 0.8 in KO group vs . 0.7 ± 0.4 in floxed group; attack duration: 10.1 ± 2.0 s in KO group vs . 1.1 ± 0.6 s in floxed group, n = 10, p < 0.01). Furthermore, the KO mice exhibited elevated plasma level of Klotho (321.4 ± 16.3 pg/ml in KO group vs. 254.1 ± 9.8 pg/ml in floxed group, n = 11-12, p < 0.01) that is known to promote energy expenditure in addition to its cardiorenal protective actions. In cultured renal HK2 cells, recombinant soluble PRR (sPRR-His) downregulated Klotho mRNA and protein expression by 29.8% and 37.9%, respectively. Overall, the present study uncovered a novel role of DCT PRR in the regulation of energy metabolism and behavior, part of which may be mediated by antagonism of Klotho action.

Reduced adipocyte glutaminase activity promotes energy expenditure and metabolic health

Glutamine and glutamate are interconverted by several enzymes and alterations in this metabolic cycle are linked to cardiometabolic traits. Herein, we show that obesity-associated insulin resistance is characterized by decreased plasma and white adipose tissue glutamine-to-glutamate ratios. We couple these stoichiometric changes to perturbed fat cell glutaminase and glutamine synthase messenger RNA and protein abundance, which together promote glutaminolysis. In human white adipocytes, reductions in glutaminase activity promote aerobic glycolysis and mitochondrial oxidative capacity via increases in hypoxia-inducible factor 1α abundance, lactate levels and p38 mitogen-activated protein kinase signalling. Systemic glutaminase inhibition in male and female mice, or genetically in adipocytes of male mice, triggers the activation of thermogenic gene programs in inguinal adipocytes. Consequently, the knockout mice display higher energy expenditure and improved glucose tolerance compared to control littermates, even under high-fat diet conditions. Altogether, our findings highlight white adipocyte glutamine turnover as an important determinant of energy expenditure and metabolic health.

Effects of intestine-specific deletion of FGF15 on the development of fatty liver disease with vertical sleeve gastrectomy.

Vertical sleeve gastrectomy (SGx) is a type of bariatric surgery to treat morbid obesity and metabolic dysfunction-associated steatotic liver disease (MASLD). The molecular mechanisms of SGx to improve MASLD are unclear, but increased bile acids (BAs) and FGF19 (mouse FGF15) were observed. FGF15/19 is expressed in the ileum in response to BAs and is critical in not only suppressing BA synthesis in the liver but also promoting energy expenditure. We hypothesized the reduction of obesity and resolution of MASLD by SGx may be mediated by FGF15/19. First, we conducted hepatic gene expression analysis in obese patients undergoing SGx, with the results showing increased expression of FGF19 in obese patients' livers. Next, we used wild-type and intestine-specific Fgf15 knockout mice (Fgf15ile-/-) to determine the effects of FGF15 deficiency on improving the metabolic effects. SGx improved metabolic endpoints in both genotypes, evidenced by decreased obesity, improved glucose tolerance, and reduced MASLD progression. However, Fgf15ile-/- mice showed better improvement compared to wild-type mice after SGx, suggesting that other mediators than FGF15 are also responsible for the beneficial effects of FGF15 deficiency. Further gene expression analysis in brown adipose tissue suggests increased thermogenesis. FGF15 deficiency, the larger BA pool and higher levels of secondary BAs may increase energy expenditure in extrahepatic tissues, which may be responsible for improved metabolic functions following SGx.

Macrophage ATG16L1 expression suppresses metabolic dysfunction-associated steatohepatitis progression by promoting lipophagy.

Metabolic dysfunction-associated steatohepatitis (MASH) is an unmet clinical challenge due to the rapid increased occurrence but lacking approved drugs. Autophagy-related protein 16-like 1 (ATG16L1) plays an important role in the process of autophagy, which is indispensable for proper biogenesis of the autophagosome, but its role in modulating macrophage-related inflammation and metabolism during MASH has not been documented. Here, we aimed to elucidate the role of ATG16L1 in the progression of MASH. Expression analysis was performed with liver samples from human and mice. MASH models were induced in myeloid-specific Atg16l1-deficient and myeloid-specific Atg16l1-overexpressed mice by high-fat and high-cholesterol diet or methionine- and choline-deficient diet to explore the function and mechanism of macrophage ATG16L1 in MASH. Macrophage-specific Atg16l1 knockout exacerbated MASH and inhibited energy expenditure, whereas macrophage-specific Atg16l1 transgenic overexpression attenuated MASH and promotes energy expenditure. Mechanistically, Atg16l1 knockout inhibited macrophage lipophagy, thereby suppressing macrophage β-oxidation and decreasing the production of 4-hydroxynonenal, which further inhibited stimulator of interferon genes(STING) carbonylation. STING palmitoylation was enhanced, STING trafficking from the endoplasmic reticulum to the Golgi was promoted, and downstream STING signaling was activated, promoting proinflammatory and profibrotic cytokines secretion, resulting in hepatic steatosis and hepatic stellate cells activation. Moreover, Atg16l1-deficiency enhanced macrophage phagosome ability but inhibited lysosome formation, engulfing mtDNA released by pyroptotic hepatocytes. Increased mtDNA promoted cGAS/STING signaling activation. Moreover, pharmacological promotion of ATG16L1 substantially blocked MASH progression. ATG16L1 suppresses MASH progression by maintaining macrophage lipophagy, restraining liver inflammation, and may be a promising therapeutic target for MASH management.

Irisin administration modifies ovary mast cell numbers, ovarian angiogenesis, and oxytocin levels in obese rats

Exercise hormone irisin, a thermogenic adipo-myokine, promotes energy expenditure by white adipose tissue browning. Considering that irisin improves the white adipose tissue metabolic profile and increases whole-body energy expenditure, it is thought that irisin may be a potential new therapeutic target for the treatment of the growing epidemic of obesity. The roles of mast cells and angiogenesis in the pathogenesis of obesity are known, and the importance of loss of mast cell function and antiangiogenic agents in the treatment of obesity has gained prominence in recent years. In addition, the therapeutic efficacy of oxytocin for obesity, by inducing browning and stimulating thermogenesis, is also noteworthy. To understand better the mechanisms involved in the therapeutic effect of irisin on obesity, the present study evaluated the effects of irisin treatment on high-fat diet-induced, obese female rats, focusing on the number of ovary mast cells, and ovarian angiogenesis and serum oxytocin levels. Our findings showed that ovary mast cell numbers, corpus luteum angiogenesis, and vascular endothelial growth factor (VEGF) immunoreactivity in ovarian tissues increased with obesity and then significantly decreased with irisin administration. Also, it was determined that the increased serum oxytocin levels with obesity, increased markedly depending on irisin administration in obese female rats. Taken together, our findings revealed that irisin can well be considered as a potential therapeutic agent in the treatment of obesity by reducing mast cells and angiogenesis, and promoting oxytocin secretion.

A celastrol-loaded DNA nano-patroller regulates hypothalamus leptin sensitivity and adipose energy expenditure for anti-obesity therapy

Obesity is a chronic metabolic disease mainly caused by fat accumulation. Well-recognized anti-obesity therapies are lacking. Celastrol is a bioactive small-molecule drug extracted from the roots of Tripterygium Wilfordii, which has excellent anti-obesity efficacy. However, the low bioavailability and permeability of celastrol limit its clinical applications. Meanwhile, tetrahedral framework nucleic acid (tFNA) represents a nucleic acid nanomaterial with suitable biocompatibility and tissue and cell permeability. Therefore, this study aimed to use tFNA as a delivery carrier for celastrol for the first time. tFNA efficiently loaded celastrol with proper stability and in vivo bio-distribution. Celastrol-loaded tFNA simultaneously rescued leptin resistance in the hypothalamus and promoted energy expenditure in adipose tissues, acting as a systemic “nano-patroller” in search of various abnormal conditions. Compared to the celastrol monomer, celastrol-loaded tFNA exerted superior inhibitory effects on fat accumulation, obesity, inflammation, and insulin resistance. In conclusion, tFNA is a promising tool for deeper anti-obesity applications of celastrol.

Imeglimin improves systemic metabolism by targeting brown adipose tissue and gut microbiota in obese model mice

Imeglimin is a recently developed anti-diabetic drug that could concurrently promote insulin secretion and insulin sensitivity, while its mechanisms of action are not fully understood. Here we show that imeglimin administration could protect mice from high fat diet-induced weight gain with enhanced energy expenditure and attenuated whitening of brown adipose tissue. Imeglimin administration led to significant alteration of gut microbiota, which included an increase of Akkermansia genus, with attenuation of obesity-associated gut pathologies. Ablation of microbiota by antibiotic treatment partially abrogated the insulin sensitizing effects of imeglimin, while not affecting its actions on body weight gain or brown adipose tissue. Collectively, our results characterize imeglimin as a potential agent promoting energy expenditure and gut integrity, providing new insights into its mechanisms of action.

Deletion of the mitochondrial calcium uniporter in adipose tissue promotes energy expenditure and alleviates diet-induced obesity

ObjectiveStudies have shown a correlation between obesity and mitochondrial calcium homeostasis, yet it is unclear whether and how Mcu regulates adipocyte lipid deposition. This study aims to provide new potential target for the treatment of obesity and related metabolic diseases, and to explore the function of Mcu in adipose tissue. MethodsWe firstly investigated the role of mitoxantrone, an Mcu inhibitor, in the regulation of glucose and lipid metabolism in mouse adipocytes (3T3-L1 cells). Secondly, C57BL/6J mice were used as a research model to investigate the effects of Mcu inhibitors on fat accumulation and glucose metabolism in mice on a high-fat diet (HFD), and by using CRISPR/Cas9 technology, adipose tissue-specific Mcu knockdown mice (Mcufl/+ AKO) and Mcu knockout of mice (Mcufl/fl AKO) were obtained, to further investigate the direct effects of Mcu on fat deposition, glucose tolerance and insulin sensitivity in mice on a high-fat diet. ResultsWe found the Mcu inhibitor reduced adipocytes lipid accumulation and adipose tissues mass in mice fed an HFD. Both Mcufl/+ AKO mice and Mcufl/fl AKO mice were resistant to HFD-induced obesity, compared to control mice. Mice with Mcufl/fl AKO showed improved glucose tolerance and insulin sensitivity as well as reduced hepatic lipid accumulation. Mechanistically, inhibition of Mcu promoted mitochondrial biogenesis and adipocyte browning, increase energy expenditure and alleviates diet-induced obesity. ConclusionsOur study demonstrates a link between adipocyte lipid accumulation and mCa2+ levels, suggesting that adipose-specific Mcu deficiency alleviates HFD-induced obesity and ameliorates metabolic disorders such as insulin resistance and hepatic steatosis. These effects may be achieved by increasing mitochondrial biosynthesis, promoting white fat browning and enhancing energy metabolism.

Foxj3 Regulates Thermogenesis of Brown and Beige Fat Via Induction of PGC-1α.

Enhancing the development and thermogenesis in brown and beige fat represents a potential treatment for obesity. In the present study, we show that Foxj3 expression in fat is stimulated by cold exposure and a β-adrenergic agonist. Adipose-specific Foxj3 knockout impairs the thermogenic function of brown fat, leading to morphological whitening of brown fat and obesity. Adipose Foxj3-deficient mice display increased fasting blood glucose levels and hepatic steatosis on a chow diet. Foxj3 deficiency inhibits the browning of inguinal white adipose tissue (iWAT) following β3-agonist treatment of mice. Furthermore, depletion of Foxj3 in primary brown adipocytes reduces the expression of thermogenic genes and cellular respiration, indicating that the Foxj3 effects on the thermogenic program are cell autonomous. In contrast, Foxj3 overexpression in primary brown adipocytes enhances the thermogenic program. Moreover, AAV-mediated Foxj3 overexpression in brown fat and inguinal WAT increases energy expenditure and improves systemic metabolism on either a chow diet or a high-fat diet. Finally, Foxj3 deletion in fat inhibits the β3 agonist-mediated induction of WAT browning and brown adipose tissue thermogenesis. Mechanistically, cold-inducible Foxj3 stimulates the expression of PGC-1α and UCP1, subsequently promoting energy expenditure. The present study identifies Foxj3 as a critical regulator of fat thermogenesis, and targeting Foxj3 in fat might be a therapeutic strategy for treating obesity and metabolic diseases.

CXCL13 promotes thermogenesis in mice via recruitment of M2 macrophage and inhibition of inflammation in brown adipose tissue.

Brown adipose tissue (BAT) is mainly responsible for mammalian non-shivering thermogenesis and promotes energy expenditure. Meanwhile, similar to white adipose tissue (WAT), BAT also secretes a variety of adipokines to regulate metabolism through paracrine, autocrine, or endocrine ways. The chemokine C-X-C motif chemokine ligand-13 (CXCL13), a canonical B cell chemokine, functions in inflammation and tumor-related diseases. However, the role of CXCL13 in the adipose tissues is unclear. The expression of CXCL13 in BAT and subcutaneous white adipose tissue (SWAT) of mice under cold stimulation were detected. Local injection of CXCL13 into BAT of normal-diet and high-fat-diet induced obese mice was used to detect thermogenesis and determine cold tolerance. The brown adipocytes were treated with CXCL13 alone or in the presence of macrophages to determine the effects of CXCL13 on thermogenic and inflammation related genes expression in vitro. In this study, we discovered that the expression of CXCL13 in the stromal cells of brown adipose tissue significantly elevated under cold stimulation. Overexpression of CXCL13 in the BAT via local injection could increase energy expenditure and promote thermogenesis in obese mice. Mechanically, CXCL13 could promote thermogenesis via recruiting M2 macrophages in the BAT and, in the meantime, inhibiting pro-inflammatory factor TNFα level. This study revealed the novel role of adipose chemokine CXCL13 in the regulation of BAT activity and thermogenesis.

SAT649 Org43553, The First Low-molecular-weight Agonist Of The Human Luteinizing Hormone Receptor Induces Leanness And Energy Expenditure In Mice

Abstract Disclosure: D. Lizneva: None. A. Gumerova: None. K. Ievleva: None. O. Barak: None. F. Korkmaz: None. J. Gimenez Roig: None. T. Frolinger: None. G. Pevnev: None. F. Sultana: None. N. Kramskiy: None. S. Wizman: None. M. Orloff: None. A.R. Pallapati: None. S. Rojekar: None. V. Ryu: None. O. Moldavski: None. T. Yuen: None. M. Zaidi: None. We provide compelling evidence that LH is a pro–lean hormone, and that ORG43553, the first low-molecular-weight agonist of the luteinizing hormone receptor (LHCGR) induces leanness and promotes energy expenditure in mice. We detected Lhcgr transcripts in white adipose tissue (WAT) depots in male and female C57BL/6 mice (qPCR, IHC, RNAscope, Sanger sequencing), but not in Lhcgr-/- mice. Intraperitoneal AlexaFluor-488–labeled hCG bound to gonadal and subcutaneous fat pads in wild type mice, but not in Lhcgr-/- mice. Following i.v. 89Zr–LH injection, radioactivity was detected in mesenteric, inguinal and gonadal WAT. LH, hCG and ORG43553 rapidly induced ERK1/2 phosphorylation in differentiated 3T3.L1 cells. Female and male Lhcgr+/- mice on normal chow and high–fat diet, respectively, became obese, importantly, without changes in sex steroids. The gene–dosage effect of Lhcgr depletion suggests a dominant physiologic action of LH on body composition. 14–week–old male C57BL/6 mice were fed on high–fat diet and injected, i.p., with LH, hCG or vehicle, twice–a–week, for 6 weeks. Both LH and hCG markedly reduced body fat accrual (qNMR) but triggered a rise in serum testosterone. The hCG–induced lean phenotype persisted despite androgen receptor blockade by flutamide—confirming that the pro–lean actions of LH and hCG were largely independent of testosterone. Furthermore that LH failed to inhibit fat accrual in Lhcgr-/- mice testified to its action via the LHCGR. Injection of ORG43553 into male C57BL/6 mice for 9 weeks caused a significant reduction in fat mass (qNMR), with reduced WAT weight in fat depots. Remarkably, serum testosterone remained unchanged confirming that the anti–adiposity effect of ORG43553 was independent of testosterone. To study the mechanism of LHCGR activation on body fat, 3T3.L1 adipocytes were treated with hCG or ORG43553 for 12 hours. This resulted in reduced oil droplet accumulation. 3T3-L1–derived organoids treated with LH, hCG or ORG43553 also displayed a substantial reduction in the differentiated layer compared to vehicle–treated organoids. To study whether, in addition to reducing adipocyte differentiation, LHCGR agonism also enhanced thermogenesis, 3T3-L1 adipocytes were pretreated with ORG43553 for 1 hour before measuring oxygen consumption rate (OCR) on a Seahorse Xf96 Analyzer. ORG43553 increased OCR at baseline and upon oligomycin exposure, indicating mitochondria proton leak (thermogenesis). To confirm increased energy expenditure in vivo, mice were injected, s.c., with ORG43553 or vehicle. Oxygen consumption (VO2) and energy expenditure (EE) increased acutely in ORG43553–treated mice, with no change in locomotor activity. The findings suggest that ORG45335, which has been tested in humans for infertility, can potentially become a candidate drug for obesity. Presentation: Saturday, June 17, 2023

Bioactive Properties, Bioavailability Profiles, and Clinical Evidence of the Potential Benefits of Black Pepper (Piper nigrum) and Red Pepper (Capsicum annum) against Diverse Metabolic Complications.

The consumption of food-derived products, including the regular intake of pepper, is increasingly evaluated for its potential benefits in protecting against diverse metabolic complications. The current study made use of prominent electronic databases including PubMed, Google Scholar, and Scopus to retrieve clinical evidence linking the intake of black and red pepper with the amelioration of metabolic complications. The findings summarize evidence supporting the beneficial effects of black pepper (Piper nigrum L.), including its active ingredient, piperine, in improving blood lipid profiles, including reducing circulating levels of total cholesterol, low-density lipoprotein cholesterol, and triglycerides in overweight and obese individuals. The intake of piperine was also linked with enhanced antioxidant and anti-inflammatory properties by increasing serum levels of superoxide dismutase while reducing those of malonaldehyde and C-reactive protein in individuals with metabolic syndrome. Evidence summarized in the current review also indicates that red pepper (Capsicum annum), together with its active ingredient, capsaicin, could promote energy expenditure, including limiting energy intake, which is likely to contribute to reduced fat mass in overweight and obese individuals. Emerging clinical evidence also indicates that pepper may be beneficial in alleviating complications linked with other chronic conditions, including osteoarthritis, oropharyngeal dysphagia, digestion, hemodialysis, and neuromuscular fatigue. Notably, the beneficial effects of pepper or its active ingredients appear to be more pronounced when used in combination with other bioactive compounds. The current review also covers essential information on the metabolism and bioavailability profiles of both pepper species and their main active ingredients, which are all necessary to understand their potential beneficial effects against metabolic diseases.

Chronic consumption of avocado seed (Persea americana) promotes a negative energy balance and body weight reduction in high-fat diet exposed mice: Implications for functional foods

Obesity is the main challenge for public health systems. Functional foods have emerged as an alternative to the ineffectiveness of pharmacological therapies. However, it is necessary to investigate to find sources of raw material for its preparation. The aim of this work was to evaluate the functional effects of residual avocado seed in diet-induced obese mice. Animals were fed a high-fat diet supplemented with avocado seed (1.25%) for 6 weeks. Body weight, food intake, satiety, physical activity, and energy expenditure-involved gene expression were measured. Supplementation with avocado seed led to reduced body weight, delayed satiety, increased physical activity, and induced Dio2 and Adrb1 expression in hypothalamus and white adipose tissue, respectively. No changes in markers of hepatic injury were observed. In conclusion, avocado seed exerts functional effects on obese mice, by promoting energy expenditure, without toxicity effects, making it possible to use this by-product in the development of functional foods.

Liver mitochondrial cristae organizing protein MIC19 promotes energy expenditure and pedestrian locomotion by altering nucleotide metabolism

Liver mitochondria undergo architectural remodeling that maintains energy homeostasis in response to feeding and fasting. However, the specific components and molecular mechanisms driving these changes and their impact on energy metabolism remain unclear. Through comparative mouse proteomics, we found that fasting induces strain-specific mitochondrial cristae formation in the liver by upregulating MIC19, a subunit of the MICOS complex. Enforced MIC19 expression in the liver promotes cristae formation, mitochondrial respiration, and fatty acid oxidation while suppressing gluconeogenesis. Mice overexpressing hepatic MIC19 show resistance to diet-induced obesity and improved glucose homeostasis. Interestingly, MIC19 overexpressing mice exhibit elevated energy expenditure and increased pedestrian locomotion. Metabolite profiling revealed that uracil accumulates in the livers of these mice due to increased uridine phosphorylase UPP2 activity. Furthermore, uracil-supplemented diet increases locomotion in wild-type mice. Thus, MIC19-induced mitochondrial cristae formation in the liver increases uracil as a signal to promote locomotion, with protective effects against diet-induced obesity.

Transcriptomic Analysis Reveals Fibroblast Growth Factor 11 (FGF11) Role in Brown Adipocytes in Thermogenic Regulation of Goats.

Brown adipose tissue (BAT) is the main site of adaptive thermogenesis, generates heat to maintain body temperature upon cold exposure, and protects against obesity by promoting energy expenditure. RNA-seq analysis revealed that FGF11 is enriched in BAT. However, the functions and regulatory mechanisms of FGF11 in BAT thermogenesis are still limited. In this study, we found that FGF11 was significantly enriched in goat BAT compared with white adipose tissue (WAT). Gain- and loss-of-function experiments revealed that FGF11 promoted differentiation and thermogenesis in brown adipocytes. However, FGF11 had no effect on white adipocyte differentiation. Furthermore, FGF11 promoted the expression of the UCP1 protein and an EBF2 element was responsible for UCP1 promoter activity. Additionally, FGF11 induced UCP1 gene expression through promoting EBF2 binding to the UCP1 promoter. These results revealed that FGF11 promotes differentiation and thermogenesis in brown adipocytes but not in white adipocytes of goats. These findings provide evidence for FGF11 and transcription factor regulatory functions in controlling brown adipose thermogenesis of goats.

1661-P: The Myokine Irisin Is Endocytosed and Signals through an αV Integrin-Independent Mechanism in Pancreatic ß-Cells

Irisin is a hormone secreted by skeletal muscle, able to improve metabolic homeostasis and promote energy expenditure. We have previously demonstrated that irisin protects human and rodent β-cells and pancreatic islets from lipotoxicity-induced apoptosis, increases insulin biosynthesis and glucose-stimulated insulin secretion (GSIS), and promotes β-cell proliferation, both in vitro and in vivo in mice. Irisin may also restore the defects that are characteristic of islets from T2D patients. Although it has been demonstrated that irisin mediates its effects on bone and fat via αV integrin receptors, the presence of an irisin receptor in β-cells has not been reported. In INS-1E cells, we found that irisin activates its intracellular signalling and enhances GSIS in the presence of a specific αV integrin knockdown or a chemical inhibitor of cellular integrins (RGDS), thus excluding the involvement of integrin receptors in irisin effects. Through a pull-down assay/mass spectrometry approach, we identified 102 irisin interactors in human pancreatic islets, mostly belonging to intracellular compartments (i.e., vesicles and membrane rafts), and not including canonical membrane receptors. We therefore hypothesized that irisin could be endocytosed in pancreatic β-cells and confirmed this by immunoblotting and immunofluorescence techniques. In addition, nystatin, an inhibitor of lipid-raft dependent endocytosis, reduced irisin entry into β-cells. These results suggest for the first time that irisin effects on pancreatic β-cells are independent of engaging the αV integrin receptor and may instead depend on its endocytosis. These results are important beyond irisin, as they propose a potential new mechanism of action for peptide hormones. In addition, we highlight the possibility that the same hormone, i.e. irisin, may signal through different receptors in different target tissues. Disclosure N.Marrano: None. A.Borrelli: None. G.Biondi: None. M.Rella: None. A.Cignarelli: Speaker's Bureau; Eli Lilly and Company, Novo Nordisk, Sanofi. S.Perrini: None. L.Laviola: Advisory Panel; A. Menarini Diagnostics, Boehringer Ingelheim Inc., Eli Lilly and Company, Novo Nordisk, Roche Diabetes Care, Sanofi, Other Relationship; Medtronic, Speaker's Bureau; Abbott, Terumo Corporation. F.Giorgino: Advisory Panel; Boehringer-Ingelheim, Amarin Corporation, Medtronic, Roche Diabetes Care, Sanofi, Bayer Inc., Novo Nordisk, Consultant; Novo Nordisk, Lilly, Research Support; Lilly, Roche Diabetes Care, AlfaSigma, Speaker's Bureau; Abbott, Boehringer-Ingelheim, Lilly, Sanofi, Medscape. A.Natalicchio: Other Relationship; AstraZeneca, Novo Nordisk, Sanofi, Boehringer-Ingelheim, Lilly.

Adipocyte G Protein-Coupled Receptors as Potential Targets for Novel Antidiabetic Drugs.

The functional state of adipocytes plays a central role in regulating numerous important metabolic functions, including energy and glucose homeostasis. While white adipocytes store excess calories as fat (triglycerides) and release free fatty acids as a fuel source in times of need, brown and beige adipocytes (so-called thermogenic adipocytes) convert chemical energy stored in substrates (e.g., fatty acids or glucose) into heat, thus promoting energy expenditure. Like all other cell types, adipocytes express many G protein-coupled receptors (GPCRs) that are linked to four major functional classes of heterotrimeric G proteins (Gs, Gi/o, Gq/11, and G12/13). During the past few years, novel experimental approaches, including the use of chemogenetic strategies, have led to a series of important new findings regarding the metabolic consequences of activating or inhibiting distinct GPCR/G protein signaling pathways in white, brown, and beige adipocytes. This novel information should guide the development of novel drugs capable of modulating the activity of specific adipocyte GPCR signaling pathways for the treatment of obesity, type 2 diabetes, and related metabolic disorders.