Increased Expression Of Uncoupling Protein Research Articles

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.

Breast cancer cell-derived exosome-delivered microRNA-155 targets UBQLN1 in adipocytes and facilitates cancer cachexia-related fat loss.

Cachexia occurrence and development are associated with loss of white adipose tissues, which may be involved with cancer-derived exosomes. This study attempted to characterize the functional mechanisms of bc cell-derived exosomes-loaded microRNA (miR)-155 in cancer cachexia-related fat loss. Exosomes were incubated with preadipocytes and cellular lipid droplet accumulation was observed using oil red O staining. Western blots evaluated the cellular levels of lipogenesis marker peroxisome proliferator activated receptor gamma (PPARγ) and adiponectin, C1Q and collagen domain containing (AdipoQ). Differentiated adipocytes were incubated with exosomes, and phosphate hormone sensitive lipase (P-HSL), adipose triglyceride lipase (ATGL), and glycerol were detected in adipocytes, in addition to uncoupling protein 1 (UCP1) and leptin levels. A mouse model of cancer cachexia was established where cancer exosomes were injected intravenously. The changes in body weight and tumor-free body weights were recorded and serum glycerol levels and lipid accumulation in adipose tissues were determined. Also, the relationship between miR-155 and UBQLN1 was predicted and verified. bc exosome treatment reduced PPARγ and AdipoQ protein levels, promoted the levels of P-HSL and ATGL proteins, facilitated glycerol release, increased UCP1 expression, and lowered leptin expression in adipocytes. Exosomal miR-155 inhibited lipogenesis in preadipocytes and boosted the browning of white adipose tissues. miR-155 downregulation alleviated cancer exosome-induced browning of white adipose tissues and fat loss. Mechanistically, miR-155 targeted UBQLN1, and UBQLN1 upregulation reversed the impacts of cancer exosomes. miR-155 loaded by bc cell-derived exosomes significantly affects white adipose browning and inhibition of cancer-derived exosomes.

Amelioration of Cardiac Autonomic Dysfunction Mitigates Perivascular and Perirenal Adipose Inflammation and Cardiorenal Involvement in Prediabetes

BackgroundEarly metabolic impairment is associated with significant cardiorenal risk. Specifically, subtle serum insulin and lipids changes in prediabetes trigger cardioautonomic and renovascular deterioration. Interestingly, data from our laboratory suggest that these insidious alterations are triggered by perirenal and perivascular adipose inflammation in response to hypoxia evoked by a localized increase in uncoupling protein1 (UCP1) expression and activity. This affects the adjacent organs in a paracrine manner.HypothesisIncreased UCP1 expression is triggered by sympathetic stimulation. The sympathovagal imbalance in early metabolic dysfunction underlies the observed localized adipose pool involvement. Pharmacological interventions to offset the sympathetic predominance should prevent increased UCP1 expression and inflammation, and reverse cardiorenal manifestations.MethodsA non‐obese prediabetic rat model was induced by twelve weeks of hypercaloric feeding. Moxonidine and galantamine were administered orally at daily doses of 2.4 mg/Kg and 4 mg/Kg for the last two weeks of feeding to reduce and facilitate sympathetic and parasympathetic discharge, respectively. Baroreflex sensitivity and renovascular reactivity were assessed by invasive hemodynamics and in isolated perfused kidneys, respectively. Adipose tissue T Cell distribution and macrophage polarization were examined by flow cytometry.ResultsCorrecting the autonomic imbalance in prediabetic rats with either moxonidine or galantamine restored cardioautonomic and renovascular activity to those observed in control rats. Although prediabetic rats showed an increased oxidative stress and proinflammatory cytokine production in both adipose pools, no change in T Cell population distribution was observed. However, the increased M1/M2 macrophage polarization profile observed in prediabetic rats was reversed by either drug treatment. This was associated with a normalization of UCP1 expression and hypoxic status.ConclusionsPharmacological interventions to reverse sympathetic predominance could be of therapeutic value treating perivascular and perirenal adipose inflammation that cause early cardiorenal manifestations of prediabetes.

CREG1 improves diet-induced obesity via uncoupling protein 1-dependent manner in mice.

Thermogenic brown and beige adipocytes express uncoupling protein 1 (UCP1) and stimulate energy metabolism, protecting against obesity and metabolic diseases such as type 2 diabetes and hyperlipidemia. Cellular repressor of E1A-stimulated genes 1 (CREG1) can stimulate thermogenic fat formation, induce UCP1, and reduce diet-induced obesity (DIO) in mice at normal room temperature. In this study, we investigated the effect of CREG1 administration and the importance of UCP1 in DIO inhibition under thermoneutral conditions at 30°C, which attenuate thermogenic fat formation. Interestingly, subcutaneous administration of recombinant CREG1 protein via an osmotic pump in C57BL/6J mice for four weeks increased UCP1 expression in interscapular brown adipose tissue (IBAT), inhibited visceral white fat hypertrophy with partial browning, and reduced DIO compared to that in PBS-treated mice. The mRNA expression of energy metabolism-related genes was significantly increased in the IBAT of CREG1-treated mice compared to that in PBS-treated mice. In contrast, adipocyte-specific overexpression of CREG1 failed to improve DIO in UCP1-knockout mice at thermoneutrality. Our results indicate the therapeutic potential of CREG1 administration for obesity under thermogenic fat-attenuating conditions and highlight the indispensable role of UCP1 in the DIO-inhibitory effect of CREG1.

The Expression of the Low-Density Lipoprotein Receptor Modulates the Effects of Hypogonadism on Mitochondrial Activity in Different Brain Domains

Background: Testosterone deficiency (TD), brain mitochondrial uncoupling protein 2 (UCP2), and the low-density lipoprotein receptor (LDLR) are independently linked to the triggering of several behavioral disorders. Here, we investigated how TD impacts mitochondrial activity and apoptosis in different brain domains in the presence and absence of LDLR. Materials and Methods: Sham-operated or surgically castrated C57BL/6 or LDLR-deficient (Ldlr−/−) mice were fed a western-type diet for 12 weeks. Then, mitochondrial UCP2 and cytochrome c (Cytc) relative protein levels were measured as markers of uncoupling and oxidative phosphorylation, respectively, in tissue specimens from different brain domains. The ratio of the relative cytoplasmic Cytc levels over the relative mitochondrial Cytc levels (CM ratio) was used as a biochemical marker of Cytc-dependent apoptosis. Results: In cerebral hemispheres and the cerebellum area of both C57BL/6 and Ldlr−/− mice, castration resulted in increased UCP2, suggesting protection from hypogonadism-induced oxidative stress. In the broader midbrain, castration reduced UCP2 expression in C57BL/6 mice but not in Ldlr−/− mice, suggesting that LDLR deficiency protects from oxidative stress in this region. CM ratio was ≤1 after castration in these three brain domains, suggesting increased protection from Cytc-dependent apoptosis. In diencephalon, castration had no effect on UCP2 and CM ratio in C57BL/6 mice but led to increased UCP2 expression and increased CM ratio in Ldlr−/− mice, suggesting an increase in apoptosis in the diencephalon of castrated Ldlr−/− mice. Conclusions: TD in Ldlr−/− mice fed a western-type diet is associated with protection from oxidative stress but could contribute to the emergence of behavioral or systemic impairments linked to apoptosis in the diencephalon.

Lipoxin A4 promotes adipogenic differentiation and browning of mouse embryonic fibroblasts.

Recently, it has been irrefutably discovered that brown adipocytes dissipate energy as heat and protect against obesity. Researchers make great efforts to explore approaches for its activation. Lipoxin A4 (LXA4) has been proven to reverse adipose tissue inflammation and improve insulin resistance, but its function on brown adipocyte differentiation has been poorly understood, which therefore to be investigated in the present study. Mouse embryonic fibroblasts (MEFs) were induced and differentiated to model brown adipocytes, and treated with LXA4 at 0, 1, 5, and 10nM for 0-14 d. Afterwards, Oil Red O staining detected lipid droplets. In differentiated MEFs with or without LXA4 (10nM) treatment, western blot and quantitative real-time polymerase chain reaction (qRT-PCR) assessed adipocyte browning marker uncoupling protein 1 (UCP-1), and brown adipogenesis markers peroxisome proliferator-activated receptor gamma (PPARγ), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), cyclooxygenase-2 (COX-2), and positive regulation domain containing 16 (PRDM16) as well as lipogenic genes of stearoyl-CoA desaturase 1 (SCD1), fatty acid synthase (FASN), glucose transporter type 4 (GLUT4), and carbohydrate response element binding protein (ChREBP). The induced differentiation of MEFs toward brown adipocytes was successful. LXA4 promoted intracellular accumulation of lipid droplets of induced cells and increased UCP-1 expression in a dose- or time-dependent manner. Under the administration of LXA4, brown adipogenesis markers and lipogenic genes were further upregulated. LXA4 made a contribution to induce differentiation of MEFs to brown adipocytes, which could be regarded a new drug target for obesity management.

Abstract 9725: Autonomic Modulation Mitigates Perivascular and Perirenal Adipose Inflammation and Consequent Cardiorenal Involvement in Prediabetes

Background: Early metabolic impairment is associated with significant cardiorenal risk. Specifically, subtle serum insulin and lipids changes in prediabetes trigger cardioautonomic and renovascular deterioration. Interestingly, data from our laboratory suggest that these insidious alterations are triggered by perirenal and perivascular adipose inflammation in response to hypoxia evoked by a localized increase in uncoupling protein1 (UCP1) expression and activity. This affects the adjacent organs in a paracrine manner. Hypothesis: Increased UCP1 expression is triggered by sympathetic stimulation. The sympathovagal imbalance in early metabolic dysfunction underlies the observed localized adipose pool involvement. Pharmacological interventions to offset the sympathetic predominance should prevent increased UCP1 expression and inflammation, and reverse cardiorenal manifestations. Methods: A non-obese prediabetic rat model was induced by twelve weeks of hypercaloric feeding. Moxonidine and galantamine were administered orally at daily doses of 2.4 mg/Kg and 4 mg/Kg for the last two weeks of feeding to reduce and facilitate sympathetic and parasympathetic discharge, respectively. Baroreflex sensitivity and renovascular reactivity were assessed by invasive hemodynamics and in isolated perfused kidneys, respectively. Adipose tissue T Cell distribution and macrophage polarization were examined by flow cytometry. Results: Correcting the autonomic imbalance in prediabetic rats with either moxonidine or galantamine restored cardioautonomic and renovascular activity to those observed in control rats. Although prediabetic rats showed an increased oxidative stress and proinflammatory cytokine production in both adipose pools, no change in T Cell population distribution was observed. However, the increased M 1 /M 2 macrophage polarization profile observed in prediabetic rats was reversed by either drug treatment. This was associated with a normalization of UCP1 expression and hypoxic status. Conclusions: Pharmacological interventions to reverse sympathetic predominance could be of therapeutic value treating perivascular and perirenal adipose inflammation that cause early cardiorenal manifestations of prediabetes.

Preconditioning of bull semen with sub-lethal oxidative stress before cryopreservation: Possible mechanism of mitochondrial uncoupling protein 2

Preconditioning of sperm using sub-lethal oxidative stress before cryopreservation is an innovative approach that can improve sperm cryo-survival. Mitochondrial uncoupling proteins (UCPs) are critical in reducing ROS level during stress conditions. The aim of the current study was to investigate whether mild sub-lethal stress induced by low concentrations of nitric oxide and hydrogen peroxide has a protective effect on quality parameters of post–thaw bull semen through modulations of mitochondrial uncoupling protein 2 (UCP2) expression. Semen samples were collected from 6 mature Holstein bulls, then mixed and divided into 8 aliquots: fresh, frozen control and frozen groups treated with NO: 0.1 (NO-0.1), 1(NO-1), 10 μM (NO-10), and H2O2: 0.1(H2O2-0.1), 1(H2O2-1) and 10μM (H2O2-10). A significantly higher percentage of total motility, progressive motility and viability was observed in NO-1 and H2O2-10 compared to the other frozen groups (P < 0.05). Sperm exposed to 1 μM NO and 10μM H2O2 showed significantly increased percentages of mitochondria activity and membrane integrity (P < 0.05). Moreover, the lowest percentage of apoptotic percentage was observed in the NO-1 and H2O2-10 in comparison to the other frozen groups. In addition, the expression level of UCP2 was higher in the NO-1 and H2O2-10 compared to the other groups (P < 0.05). It can be concluded that stress preconditioning of bull sperm before cryopreservation can increase UCP2 expression of sperm, that can play a protective role against cryoinjury after thawing.

The effects of mirabegron on obesity-induced inflammation and insulin resistance are associated with brown adipose tissue activation but not beiging in the subcutaneous white adipose tissue.

Mirabegron is a selective β₃-adrenergic receptors agonist, which has been recently shown to improve metabolic health in rodents and humans. In this study, we investigated the effects of 2-week mirabegron treatment on the metabolic parameters of mice with a diet-induced obesity (DIO). C57BL/6JUnib mice were divided into control (CTR) and obese (OB) groups treated with vehicle, and an OB group treated with mirabegron (OB+MIRA). The obese groups were fed a high-fat diet for 12weeks. Mirabegron (10mg/kg/day) was administrated orally by gavage from weeks 10-12. After 2weeks of mirabegron treatment, the energy expenditure was assessed with indirect calorimetry. Blood glucose, insulin, glycerol, free fatty acids (FFA), thiobarbituric acid reactive substance (TBAR), and tumour necrosis factor (TNF)-α levels were also assessed, and the HOMA index was determined. Liver tissue, brown adipose tissue (BAT), and inguinal white adipose tissue (iWAT) samples were collected for histological examination. The protein expressions of uncoupling protein 1 (UCP1) and mitochondrial transcription factor A (TFAM) were assessed using western blotting of the BAT and iWAT samples. In this study, mirabegron increased the energy expenditure and decreased adiposity in OB+MIRA. Increased UCP1 expression in BAT without changes in iWAT was also found. Mirabegron decreased circulating levels of FFA, glycerol, insulin, TNF-α, TBARS and HOMA index. DIO significantly increased the lipid deposits in the liver and BAT, but mirabegron partially reversed this change. Our findings indicate that treatment with mirabegron decreased inflammation and improved metabolism in obese mice. This effect was associated with increased BAT-mediated energy expenditure, but not iWAT beiging, which suggests that mirabegron might be useful for the treatment of obesity and diabetes.

Exercise training mitigates ER stress and UCP2 deficiency-associated coronary vascular dysfunction in atherosclerosis

Endoplasmic reticulum (ER) stress and uncoupling protein-2 (UCP2) activation are opposing modulators of endothelial dysfunction in atherosclerosis. Exercise reduces atherosclerosis plaques and enhances endothelial function. Our aim was to understand how exercise affects ER stress and UCP2 activation, and how that relates to endothelial dysfunction in an atherosclerotic murine model. Wild type (C57BL/6, WT) and apolipoprotein-E-knockout (ApoEtm1Unc, ApoE KO) mice underwent treadmill exercise training (EX) or remained sedentary for 12 weeks. Acetylcholine (ACh)-induced endothelium-dependent vasodilation was determined in the presence of an eNOS inhibitor (L-NAME), UCP2 inhibitor (genipin), and ER stress inducer (tunicamycin). UCP2, ER stress markers and NLRP3 inflammasome signaling were quantified by western blotting. p67phox and superoxide were visualized using immunofluorescence and DHE staining. Nitric oxide (NO) was measured by nitrate/nitrite assay. ACh-induced vasodilation was attenuated in coronary arterioles of ApoE KO mice but improved in ApoE KO-EX mice. Treatment of coronary arterioles with L-NAME, tunicamycin, and genipin significantly attenuated ACh-induced vasodilation in all mice except for ApoE KO mice. Exercise reduced expression of ER stress proteins, TXNIP/NLRP3 inflammasome signaling cascades, and Bax expression in the heart of ApoE KO-EX mice. Further, exercise diminished superoxide production and NADPH oxidase p67phox expression in coronary arterioles while simultaneously increasing UCP2 expression and nitric oxide (NO) production in the heart of ApoE KO-EX mice. Routine exercise alleviates endothelial dysfunction in atherosclerotic coronary arterioles in an eNOS, UCP2, and ER stress signaling specific manner, and resulting in reduced TXNIP/NLRP3 inflammasome activity and oxidative stress.

Peran biologis Uncoupling Protein 2 (UCP2) pada obesitas dan diabetes mellitus tipe 2 (DMT2)

Obesity is a symptom or disorder determined by the interaction of several environmental and genetic factors. It is a result of imbalance between energy intake and expenditure. It is also suggested that obesity increases the risk of Type 2 Diabetes Mellitus (T2DM). It has been reported that uncoupling protein 2 (UCP2) may influence the susceptibility to obesity and T2DM. The aims of this literature study is to elucidate the biological role of UCP2 in obesity and T2DM. UCP2 is a transporter of the mitochondrial inner membrane that can uncouple proton production from mitochondrial respiration, thereby dissipating energy as heat and affecting energy expenditure. UCP2 acts as a proton carrier activated by free fatty acids. Obesity and fasting can elevate plasma fatty acids. High plasma fatty acid levels can increase UCP2 mRNA levels suggesting the role of these protein in the metabolic adaptation to obesity and fasting. Moreover, UCP2 plays a role as a negative regulator of insulin secretion. In pancreatic beta cells the ratio of ATP/ADP is key signal for insulin release. Therefore, increase UCP2 expression, as seen in the pancreatic beta cell, might cause a decrease in intracellular ATP and results in the impairment of insulin secretion, which causes diabetes. Ala55Val allele of UCP2 gene, as single nucleotide polymorphisms (SNPs) may influence the susceptibility to obesity and T2DM. However, the association of this allele to obesity and diabetes is different in various populations

Effect of 5-azacytidine (5-aza) on UCP2 expression in human liver and colon cancer cells.

The function of the uncoupling protein 2 (UCP2) is different for each cancer cell. However, the mechanism of expression is still unclear. DNA methylation affects protein expression and is one factor that transforms normal cells into cancer cells. In this study, the hepatocellular carcinoma Hep3B and HepG2 cells and colorectal cancer HT-29 cells were treated with 5-azacytidine (5-aza), a DNA demethylation agent, to observe the modification of UCP2 expression and the methylation degree in the UCP2 promoter region. Promoter basal activity and degree of UCP2 expression were measured in Hep3B, HepG2, and HT-29 cells. In addition, methylation-specific PCR (MSP) was performed to investigate the degree of methylation in the UCP2 promoter region. The methylation region in the UCP2 promoter was confirmed based on bisulfite sequencing. In Hep3B cells in which UCP2 mRNA was not transcribed, the promoter basal activity was significantly higher than in HT-29 or HepG2 cells in which UCP2 mRNA was transcribed. Treatment with 5-aza increased UCP2 expression in Hep3B and HT-29 cells; however, the expression in HepG2 cells was unchanged. The UCP2 promoter in Hep3B cells has numerous methylated regions compared with HT-29 and HepG2 cells. The results of the present study revealed that inhibition of UCP2 expression in Hep3B cells was due to methylation of the promoter region. Investigating the mechanism that induces UCP2 expression in cancer cells is important to understand the function of UCP2, which could aid in cancer treatment.

Endogenous asymmetric dimethylarginine accumulation contributes to the suppression of myocardial mitochondrial biogenesis in type 2 diabetic rats

BackgroundSuppressed mitochondrial biosynthesis has been reported to be the early signal of mitochondrial dysfunction which contributes to diabetic cardiomyopathy, but the mechanism of mitochondrial biosynthesis suppression is unclear. Nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) is closely related to diabetic cardiovascular complications. This study was to determine whether endogenous ADMA accumulation was involved in the suppression of myocardial mitochondrial biogenesis in diabetic rats and to elucidate the potential mechanism in rat cardiomyocytes.MethodsType 2 diabetic rat model was induced by high-fat feeding plus single intraperitoneal injection of small dose streptozotocin (35 mg/kg). The copy number ratio of mitochondrial gene to nuclear gene was measured to reflect mitochondrial biogenesis. The promoter activity of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and its post-translational modifications were detected by dual-luciferase reporter assay and immunoprecipitation.ResultsMyocardial ADMA content was enhanced and associated with suppressions of myocardial mitochondrial biogenesis and cardiac function in parallel with PGC-1α downregulation and uncoupling protein 2 (UCP2) upregulation in the myocardium of diabetic rats compared with control rats. Similarly, ADMA and its homolog could inhibit myocardial mitochondrial biogenesis and PGC-1α expression, increase UCP2 expression and oxidative stress in vitro and in vivo. Moreover, ADMA also suppressed the promoter activity and PGC-1α expression but boosting its protein acetylation and phosphorylation in rat cardiomyocytes.ConclusionsThese results indicate that endogenous ADMA accumulation contributes to suppression of myocardial mitochondrial biogenesis in type 2 diabetic rats. The underlying mechanisms may be associated with reducing PGC-1α promoter activity and expression but boosting its protein acetylation and phosphorylation.

Intramuscular Brown Fat Activation Decreases Muscle Atrophy and Fatty Infiltration and Improves Gait After Delayed Rotator Cuff Repair in Mice

Background: Successful repair of large and massive rotator cuff (RC) tears remains a challenge at least partially because of secondary muscle atrophy and fatty infiltration. β3 Adrenergic agonists are a group of drugs that promote fat resorption through “white fat browning” of intramuscular stem cells. Purpose: To test the role of a β3 adrenergic receptor agonist, amibegron, in improving muscle quality and forelimb function in a delayed RC repair model via promoting brown/beige adipose tissue activation. Study Design: Controlled laboratory study. Methods: Three-month-old PDGFRα-GFP reporter mice, wild type C57BL/6J mice, and uncoupling protein 1 (UCP-1) knockout mice underwent unilateral supraspinatus tendon transection with a 6-week delayed tendon repair. Animals with sham surgery served as controls. Amibegron was given either immediately after tendon transection or after repair. Gait analysis was conducted to measure forelimb function at 6 weeks after tendon repair. Animals were sacrificed at 6 weeks after repair. Supraspinatus muscles were harvested and analyzed histologically. Reverse transcription polymerase chain reaction was performed to quantify gene expression related to atrophy, fibrosis, and fatty infiltration. Results: Histology of PDGFRα reporter mice showed significantly increased UCP-1 expression, suggesting white fat browning in muscle after RC repair. As administered either immediately after tendon transection or after tendon repair, amibegron significantly reduced muscle atrophy and fatty infiltration and resumed normal upper extremity gait in wild type mice. However, the effect of amibegron was not present in UCP-1 knockout mice, suggesting that the effect of amibegron in treating RC muscle atrophy and fatty infiltration is through a UCP 1–dependent mechanism. Conclusion: Amibegron reduced muscle atrophy and fatty infiltration and improved forelimb function after delayed RC repair through a UCP 1–dependent mechanism. This may be an effective clinical treatment strategy for patients to improve muscle quality after RC repair. Clinical Relevance: β3 Adrenergic agonists may serve as a new pharmacologic modality to treat RC muscle atrophy and fatty infiltration to improve clinical outcome of RC repair.

Resveratrol protects against ethanol-induced impairment of insulin secretion in INS-1 cells through SIRT1-UCP2 axis

SIRT1 has been proposed to enhance insulin secretion in β-cell through repressing the expression of uncoupling protein2 (UCP2), but whether ethanol-induced β-cell dysfunction is mediated by the disrupted SIRT1-UCP2 axis remains unknown. This study was conducted to explore the underlying mechanisms by which ethanol resulted in β-cell dysfunction and the potential protective effects of resveratrol in this process. INS-1 cells (rat pancreatic β-cell line) were cultured with ethanol in the presence or absence of resveratrol (2.5, 12.5 μmol/L). The results showed that ethanol exposure reduced glucose-stimulated insulin secretion, ATP production and SIRT1 expression but increased UCP2 expression, while supplementation with resveratrol restored the function of INS-1 cell by upregulating SIRT1 and inhibiting UCP2. Moreover, the critical role of SIRT1-UCP2 axis was further supported by the results that SIRT1 activator SRT1720 reversed ethanol-induced impairment of glucose-stimulated insulin secretion by decreasing UCP2, while SIRT1 inhibitor Ex527 abolished the beneficial effects of resveratrol. Meanwhile, NAD+ booster nicotinamide mononucleotide also counteracted the deleterious effects of ethanol by increasing SIRT1, suggesting the regulation of SIRT1-UCP2 axis may be associated with cellular NAD+/NADH ratio. In conclusion, our observations imply that ethanol induces impaired insulin secretion from INS-1 cell through disrupting SIRT1-UCP2 axis, while resveratrol may reverse this process by augmenting SIRT1 and inhibiting UCP2.

Increased UCP1 expression in the perirenal adipose tissue of patients with renal cell carcinoma

Perirenal adipose tissue (PAT) has been implicated in renal cell carcinoma (RCC). The expression of uncoupling protein 1 (UCP1) is higher in PAT compared with that in back subcutaneous adipose tissue (bSAT). The aim of the present study was to determine UCP1 expression in different parts of PAT and to analyze the correlation between UCP1 expression in PAT and RCC. PAT from the upper and lower renal poles and bSAT samples were collected from 50 patients with RCC (RCC group) and 54 patients with renal cysts (control group) who had undergone renal surgery. Both UCP1 mRNA and protein levels were found to be significantly higher and adipocytes appeared to be smaller in the PAT of the RCC group. Furthermore, the RCC group had more multilocular UCP1-positive adipocytes. UCP1 staining in the PAT was significantly stronger in the RCC group, but there was no significant difference in UCP1 staining in the bSAT between the two groups. Furthermore, Fuhrman grade and T stage were higher in the high UCP1 expression group of RCC patients. In conclusion, high UCP1 expression in the PAT may serve as an indicator of poor prognosis in RCC.

2082-P: Pharmacological Induction of Brown and Beige Adipose Tissue

Brown adipose tissue (BAT) is associated with improved metabolic homeostasis in humans, and studies in rodents indicate that subcutaneous white adipose tissue (SC WAT) beiging, which involves increased uncoupling protein 1 (UCP1) expression, also is associated with improved metabolism. The goal of this study was to determine the ability of mirabegron (a β3AR agonist), pioglitazone (a thiazolidinedione), or a combination of the drugs to induce brown and beige adipose tissue and to determine the effects on glucose and lipid homeostasis. We randomized obese, insulin-resistant (IR) research participants to mirabegron (50 mg/day), pioglitazone (30 mg/day), or combination therapy treatment groups. Euglycemic clamping, oral glucose tolerance tests, adipose tissue biopsies, and PET-CT scans were performed at baseline and after 10 weeks of treatment. Mirabegron improved glucose homeostasis (reduced HbA1c and improved oral glucose tolerance) to a similar extent as pioglitazone without side effects or weight gain. Although mirabegron treatment increased insulin sensitivity, the effect size was much smaller than pioglitazone, yet mirabegron treatment significantly increased the insulinogenic and disposition indexes, suggesting that a major part of the mechanism of mirabegron action involved improving β-cell function. Mirabegron treatment consistently induced SC WAT beiging as evidenced by increased UCP1 expression (2.4 fold increase; P&amp;lt;0.0001), but did not induce BAT, suggesting that induction of beige adipose may be part of the mechanism responsible for improved glucose homeostasis. Pioglitazone also induced beiging (1.6 fold increase in UCP1; P&amp;lt;0.01), but not BAT. The combination of mirabegron plus pioglitazone was not additive, with similar effects on glucose tolerance as single drug. These results suggest that mirabegron treatment has significant beneficial metabolic effects in obese, IR subjects through a distinct mechanism involving SC WAT beiging and improved pancreatic beta cell function. Disclosure B. Finlin: None. H. Memetimin: None. A.L. Confides: None. B. Zhu: None. Z.R. Johnson: None. E.E. Dupont-Versteegden: None. P.A. Kern: None. Funding National Institutes of Health (R01DK112282)

Eicosapentaenoic Acid Regulates Brown Adipose Tissue Function, Independently of UCP1 (FS11-01-19)

ObjectivesBrown adipose tissue (BAT) is a critical tissue in energy expenditure through its specific uncoupling protein 1 (UCP1). We previously reported that mice fed high fat (HF) diet supplemented with eicosapentaenoic acid (EPA) reduced body weight, adiposity, and insulin resistance, and increased UCP1 protein and mRNA levels of other thermogenic markers in BAT at ambient temperature. Hence, we hypothesized that these metabolic effects of EPA on BAT are in part mediated by UCP1. MethodsTo determine the role of UCP1 in obesity and BAT regulation by EPA, wild type (WT) and UCP1 knockout (KO) B6 male mice were housed at thermoneutral conditions (30°C), previously reported to induce obesity in the KO mice. Mice were fed a high-fat diet (HF, 45% kcal fat) or HF diet supplemented with 36 g/kg of AlaskOmega EPA-enriched fish oil (800 mg/g), kindly provided by Organic Technologies, for up to 14 weeks. We metabolically phenotyped these mice and investigated metabolic and molecular changes in their interscapular BAT. Specifically, we determined effects of UCP1 deficiency and EPA on BAT thermogenic and mitochondrial markers. ResultsThe previously reported beneficial metabolic effects of EPA in WT mice at ambient, including increased UCP1 expression, were attenuated or lost at thermoneutral temperature. EPA reduced weight gain and adiposity, and improved glucose tolerance in KO mice. In both diets (HF and EPA), BAT triglyceride content was increased, while mitochondrial UCP1, COX I and COX IV protein levels were decreased in the KO compared to the WT genotype (P < 0.05). EPA also increased (P < 0.05) mitochondrial DNA/nuclear DNA ratio in the KO mice. Finally, BAT PGC1α at both gene and protein levels along with whole-body oxygen consumption were increased (P < 0.05) by EPA in KO mice. EPA did not alter the calcium cycling-related markers such as sarcoplasmic/endoplasmic reticulum calcium ATPase 2b (Serca2b) and transient receptor potential vanilloid 2 (Trpv2) in any of the genotypes. ConclusionsEPA effects on BAT and mitochondrial function are independent of UCP1, and include increased mitochondrial DNA and oxygen consumption, which may be in part relate to increased PGC1α. Additional studies are required to determine fuel or mitochondrial mechanisms by which energy expenditure is increased independently of UCP1. Funding SourcesNIH/NCCIH grant # R15AT008879-01A1.

Upregulation of UCP2 Expression Protects against LPS-Induced Oxidative Stress and Apoptosis in Cardiomyocytes.

Uncoupling protein 2 (UCP2) has a cardioprotective role under septic conditions, but the underlying mechanism remains unclear. This study aimed at investigating the effects of UCP2 on the oxidative stress and apoptosis of cardiomyocytes induced by lipopolysaccharide (LPS). First, LPS increased UCP2 expression in cardiomyocytes in a time-dependent manner. LPS increased the production of lactate dehydrogenase (LDH), reactive oxygen species (ROS), and malondialdehyde (MDA) and decreased the level of superoxide dismutase (SOD). However, UCP2 knockdown increased the LPS-induced cardiac injury and oxidative stress. In addition, LPS damaged the mitochondrial ultrastructure and led to the disruption of mitochondrial membrane potential (MMP), as well as the release of mitochondrial cytochrome c. UCP2 knockdown aggravated mitochondrial injury and the release of mitochondrial cytochrome c. LPS increased the protein levels of Bax and cleaved-caspase-3, decreased the protein level of Bcl-2, and upregulated the protein level of mitogen-activated protein kinase. However, upon UCP2 knockdown, the protein levels of Bax and cleaved-caspase-3 increased even further, and the protein level of Bcl-2 was further decreased. The protein level of phosphorylated p38 was also further enhanced. Thus, UCP2 protects against LPS-induced oxidative stress and apoptosis in cardiomyocytes.

Fluvastatin Sodium Ameliorates Obesity through Brown Fat Activation.

Brown adipose tissue (BAT), an organ that burns energy through uncoupling thermogenesis, is a promising therapeutic target for obesity. However, there are still no safe anti-obesity drugs that target BAT in the market. In the current study, we performed large scale screening of 636 compounds which were approved by Food and Drug Administration (FDA) to find drugs that could significantly increase uncoupling protein 1 (UCP1) mRNA expression by real-time PCR. Among those UCP1 activators, most of them were antibiotics or carcinogenic compounds. We paid particular attention to fluvastatin sodium (FS), because as an inhibitor of the cellular hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase, FS has already been approved for treatment of hypercholesteremia. We found that in the cellular levels, FS treatment significantly increased UCP1 expression and BAT activity in human brown adipocytes. Consistently, the expression of oxidative phosphorylation-related genes was significantly increased upon FS treatment without differences in adipogenic gene expression. Furthermore, FS treatment resisted to high-fat diet (HFD)-induced body weight gain by activating BAT in the mice model. In addition, administration of FS significantly increased energy expenditure, improved glucose homeostasis and ameliorated hepatic steatosis. Furthermore, we reveal that FS induced browning in subcutaneous white adipose tissue (sWAT) known to have a beneficial effect on energy metabolism. Taken together, our results clearly demonstrate that as an effective BAT activator, FS may have great potential for treatment of obesity and related metabolic disorders.