Expression Of Uncoupling Protein Research Articles

Potential role of UCP-1 for mediating beneficial effects of exercise in an endometriosis rat model

Endometriosis is a gynecological disorder characterized by the growth of endometrial tissue in areas outside the uterus. Previous studies in our laboratory demonstrated that endometriosis animals have increased mesenteric adipose tissue (MAT), inflammation, and implanted endometrial vesicles, which are all decreased by voluntary exercise. Interestingly, the levels of Uncoupling Protein 1 (UCP-1), a mitochondrial protein, are known to be increased by exercise promoting thermogenesis, and decreasing inflammation in rodents. However, the possible role of UCP-1 in endometriosis is still unclear. Our aim was to study the effects of exercise on UCP-1 in MAT near the endometrial implants in an endometriosis rat model. Hypothesis: UCP-1 increases due to exercise decreasing the MAT and thus beneficially impacts the endometrial vesicles. Methods: Endometriosis was induced by implanting uterine tissue on the intestinal mesentery in young adult female Sprague Dawley rats where the control group only received sutures. Exercise rats had access to a running wheel after induction: ENDO-EX or SHAM-EX, while non-exercised animals didn’t (ENDO and SHAM; n=10=11/group). After sixty days of intervention, animals were sacrificed and UCP-1 immunofluorescent staining was performed on collected MAT near the vesicles (ENDO, n=3; ENDO-EX, n=3; SHAM, n=4; SHAM-EX, n=4). Results: The vesicles from ENDO-EX animals had significantly decreased average weight (p<0.05) and smaller average total area (p<0.01) compared with the ENDO group. UCP-1 staining shows a trend to increase in exercise groups when compared to non-exercise groups. Interestingly, there is a moderate negative correlation between UCP-1 expression and vesicle size (r=-.69). Conclusions: Exercise is related to increasing the UCP-1 pathways in MAT that may be associated with decreasing the size of the endometrial vesicle implants. Supported by R15AT009915 and HRD-2008186. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Role of Acetyl-CoA Synthetase Short Chain Family Member-1 on Adipocyte Thermogenic Capacity

Obesity is characterized by an increase in adipose mass and is the leading risk factor for type 2 diabetes. Recent research suggests that activation of brown or beige fat and white adipose tissue browning represent a new therapeutic strategy for metabolic diseases. Fatty acid oxidation is required for the browning of white adipose tissue (WAT) and the induction of uncoupling protein 1 (UCP1) in WAT. The Acyl-CoA Synthetase Short Chain Family Member-1 (ACSS1), an established SIRT3 deacetylation target, is central to fatty acid oxidation (FAO) and mitochondrial bioenergetics by converting acetate and CoA to acetyl-CoA. However, the biological function of ACSS1 acetylation (ACSS1-Ac) in thermogenic adipose tissue and how it contributes to metabolic changes in adipocytes has not been investigated. We have generated a novel acetylation mimic mouse where lysine 635 (K635) was mutated to glutamine (K635Q), representing constitutive ACSS1-K635-Ac. Male mice expressing Acss1 K635Q/K635Q exhibited a reduction in size and body weight. Upon 48-hour fasting, these mice exhibited hypothermia as well as decreased ATP and lactate levels. Interestingly, UCP1 gene expression was upregulated in brown adipose tissue (BAT) of the Acss1 K635Q/K635Q compared to WT and also in WAT from fasted animals. Differentiated beige adipocytes also showed higher UCP1, PGC1a and adiponectin gene expression in cells isolated from Acss1 K635Q/K635Q mice compared to WT cells. Oxygen consumption rate of these cells was lower with lower basal and ATP-coupled respiration. Acss1 K635Q/K635Q beige adipocytes failed to respond to beta-adrenergic stimulation and did not increase their respiration capacity when compared to WT cells. No differences were observed in glucose uptake and lipolysis functional assays. These results suggest that the mutation leads to a disruption of downstream signaling of UCP1. In conclusion, ACSS1-K635-Ac is a novel thermoregulator in adipose tissue that could lead to further development of new therapies for metabolic diseases. 1. Mays Cancer Center CCSG (P30 CA054174); 2. National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health, under Award Number F32-0DK122754 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Aging-related genes related to the prognosis and the immune microenvironment of acute myeloid leukemia.

Acute myeloid leukemia (AML), one of the common malignancies of the hematologic system, has progressively increased in incidence. Aging is present in both normal tissues and the tumor microenvironment. However, the relationship between senescence and AML prognosis is still not elucidated. In this study, RNA sequencing data of AML were obtained from TCGA, and prognostic prediction models were established by LASSO-Cox analysis. Differences in immune infiltration between the different risk groups were calculated using the CIBERSORT and ESTIMATE scoring methods. The KEGG and GO gene enrichment and GSEA enrichment were also used to enrich for differential pathways between the two groups. Subsequently, this study collected bone marrow samples from patients and healthy individuals to verify the differential expression of uncoupling protein 2 (UCP2) in different populations. Genipin, a UCP2 protein inhibitor, was also used to examine its effects on proliferation, cell cycle, and apoptosis in AML cell lines in vitro. It showed that aging-related genes (ARGs) expression was correlated with prognosis. And there was a significant difference in the abundance of immune microenvironment cells between the two groups of patients at high risk and low risk. Subsequently, UCP2 expression was found to be elevated in AML patients. Genipin inhibits UCP2 protein and suppresses the proliferation of AML cell lines in vitro. ARGs can be used as a predictor of prognosis in AML patients. Moreover, suppressing UCP2 can reduce the proliferation of AML cell lines, alter their cell cycle, and promote apoptosis in vitro.

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.

High-Fat-Diet Suppressed Ketone Body Utilization for Lipogenic Pathway in Brown Adipose Tissues.

Brown adipose tissue (BAT) consumes excess lipids and produces lipid metabolites as ketone bodies. These ketone bodies are then recycled for lipogenesis by the enzyme acetoacetyl-CoA synthetase (AACS). Previously, we found that a high-fat diet (HFD) upregulated AACS expression in white adipose tissue. In this study, we investigated the effects of diet-induced obesity on AACS in BAT. When 4-week-old ddY mice were fed a HFD or high-sucrose diet (HSD) for 12 weeks, a significant decrease in Aacs, acetyl-CoA carboxylase-1 (Acc-1), and fatty acid synthase (Fas) expression was observed in the BAT of the HFD group, whereas expression was not affected in the HSD group. In vitro analysis showed decreased Aacs and Fas expression in rat primary-cultured brown adipocytes following isoproterenol treatment for 24 h. In addition, the suppression of Aacs by siRNA markedly decreased the expression of Fas and Acc-1 but did not affect the expression of uncoupling protein-1 (UCP-1) or other factors. These results suggested that HFD may suppress ketone body utilization for lipogenesis in BAT and that AACS gene expression may be important for regulating lipogenesis in BAT. Therefore, the AACS-mediated ketone body utilization pathway may regulate lipogenesis under conditions of excess dietary fat.

Abstract 5046: Cerenkov luminescence imaging of interscapular brown adipose tissue using TSPO-targeting probe to overcome off-target effect of [18F]FDG

Abstract Aim/Introduction: [18F]fluorodeoxyglucose-positron emission tomography ([18F]FDG-PET) has been used as an imaging methods for measuring interscapular brown adipose tissue (iBAT) activity. However, [18F]FDG-PET has limitations for obtaining iBAT-specific images due to off-target effects with high uptake in skeletal muscle, tumors, and inflamed tissue. Uncoupling protein 1 (UCP1), a well-known biomarker for BAT, located in mitochondria also has been suggested as BAT imaging marker. Recently, UCP1 ThermoMouse was established as a reporter mouse for monitoring UCP1 expression. Translocator protein-18 kDa (TSPO) located in the mitochondria outer membrane along with UCP1 is overexpressed in BAT. TSPO targeting probe has been proposed as a potential imaging marker for iBAT imaging. To date, there have been no studies for BAT imaging using TSPO-targeting probe in UCP1 ThermoMouse reflecting UCP1 expression. Moreover, Cerenkov luminescence imaging (CLI) which captures Cerenkov radiation emitted from PET probes has been suggested as an alternative option for PET. In this study, we aim to evaluate [18F]fm-PBR28-d2 as a TSPO-targeting probe for iBAT imaging using PET and CLI in the UCP1 ThermoMouse. Materials and Methods: UCP1 ThermoMouse with insertion of a Luc2-T2A-tdTomato cassette into the initiation of codon of the Ucp1-coding sequence exon 1 were used to monitor UCP1 expression. UCP1 ThermoMouse were characterized with Western blotting and immunohistochemistry to measure the levels of UCP1 expression. PET images were acquired with SimPET, and optical images such as bioluminescence imaging (BLI), fluorescence imaging (FLI) and Cerenkov luminescence imaging (CLI) were acquired with IVIS 100. Results: BLI or FLI reflecting UCP1 expression were clearly showed iBAT in UCP1 ThermoMouse. Also, UCP1 and TSPO expression were correlated in iBAT. TSPO-targeting PET probe with [18F]fm-PBR28-d2 showed iBAT-specific signals without off-target effect in brain or heart. In addition, [18F]fm-PBR28-d2 better reflected individual variation in different UCP1 expression than [18F]FDG. In particular, higher molar activity of [18F]fm-PBR28-d2 was required to obtain better imaging quality of CLI as well as PET. In physiological changes such as cold stimulation and isoflurane exposure, we observed increased imaging signals with cold exposure and decreased imaging signals with prolonged isoflurane exposure. Conclusions: We showed that the TSPO-targeting probe is superior to [18F]FDG as a reliable imaging probe reflecting UCP1 expression in iBAT imaging. Probes with higher molar activity provide better images and are required for quantitative analysis of TSPO-CLI and PET. Our data suggest that CLI with TSPO-targeting probe could be an alternative option for PET. Citation Format: Seok-Yong Lee, Ho Rim Oh, Young-Hwa Kim, Sung-Hwan Bae, Yongseok Lee, Yun-Sang Lee, Byung Chul Lee, Gi Jeong Cheon, Keon Wook Kang, Hyewon Youn. Cerenkov luminescence imaging of interscapular brown adipose tissue using TSPO-targeting probe to overcome off-target effect of [18F]FDG. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5046.

Abstract 4836: Fasting induces greater expression of mitochondrial proteins associated with fatty acid metabolism and non-shivering thermogenesis in brown adipose tissue of knock-in ACSS1K635Q mice

Abstract Introduction: Acyl-CoA Synthetase Short Chain Family Member 1 (ACSS1) is an important mitochondrial enzyme for the production of ATP from short chain fatty acids under energetic stress. ACSS1 is highly expressed in brown adipose tissue, heart, and skeletal muscle. ACSS1 is regulated in part by a post-translational modification of ACSS1, whereby the side chain of Lysine-635 is acetylated. The activity of ACSS1 is downregulated by the acetylation of Lysine-635. The downregulation of ACSS1 activity has been shown to impose changes on fatty acid metabolism and body temperature. Our lab observed that homozygous knock-in ACSS1 mice that fasted for 48 hours were hypothermic with a temperature of 30 °C. Here, we utilized mutant mice to simulate acetylated ACSS1, to investigate the role of ACSS1K635Q in mitochondrial fatty acid metabolism and maintenance of body temperature under fasting conditions. Methods: A knock-in ACSS1 mouse model with a mutation of ACSS1K635Q was designed to model the downregulation of ACSS1. Wild Type mice and Homozygous Knock-in ACSS1K635Q mice were either fasted for 48 hours (F48) or fed with a normal diet (ND). Four experimental groups - Wild Type ND and F48 mice and Homozygous Knock-in ACSS1K635Q ND and F48 mice - were examined. Protein was extracted from 10 samples each containing 20 mg of brown adipose tissue. Tissue samples were lysed and immunoblotted with primary and secondary antibodies. Western Blot Western Blot was performed on the proteins Uncoupling Protein 1 (UCP1), UCP2, ACC, and AMPK. Membranes were imaged using the FluorChem M system, and chemiluminescence was quantified using the NIH ImageJ software. ANOVA and t-test were used to conduct statistical analysis (P < 0.05). Results: Homozygous Ki-ACSS1K635Q F48 mice expressed higher levels of UCP1 and UCP2 in BAT than Homozygous Ki-ACSS1K635Q ND mice. We observed a greater difference in UCP1 expression between Homozygous Ki-CSS1K635Q ND and F48 mice compared to the difference in UCP1 expression between Wild Type ND and F48 mice. In Wild Type and Homozygous Ki-ACSS1K635Q mice, UCP1 expression was lower than UCP2 expression. Fasting for 48 hours significantly upregulated p-AMPK in Wild Type mice. Conclusions: Under fasting conditions, metabolic processes may shift towards a greater proportion of non-shivering thermogenesis due to ACSS1 inactivity. UCP1 likely contributes more to non-shivering thermogenesis than UCP2. Understanding the impact of acetylating ACSS1 provides avenues towards developing personalized treatments that effectively respond to metabolic stressors. Citation Format: Aishani Sivasai Gargapati, Mahboubeh Varmazyad, David Gius. Fasting induces greater expression of mitochondrial proteins associated with fatty acid metabolism and non-shivering thermogenesis in brown adipose tissue of knock-in ACSS1K635Q mice. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4836.

Ginsenoside F1 administration promotes UCP1-dependent fat browning and ameliorates obesity-associated insulin resistance

Obesity-induced type 2 diabetes is mainly due to excessive free fatty acids leading to insulin resistance. Increasing thermogenesis is regarded as an effective strategy for hypolipidemia and hypoglycemia. Ginsenoside is a natural active component in Panax ginseng C.A. Meyer, and some of them enhance thermogenesis. However, there are few studies on the mechanism and target of ginsenosides enhancing thermogenesis. Using thermogenic protein uncoupling protein 1 (UCP1)-luciferase reporter assay, we identified ginsenoside F1 as a novel UCP1 activator in the ginsenosides library. Using pull down assay and inhibitor interference, we found F1 binds to β3-adrenergic receptors (β3-AR) to enhance UCP1 expression via cAMP/PKA/CREB pathway. We also investigated the ability of F1 on energy metabolism in obesity-induced diabetic mice, including body weight, body composition and energy expenditure. The results of proteomics showed that F1 significantly up-regulated thermogenesis proteins and lipolytic proteins, but down-regulated fatty acid synthesis proteins. Ginsenoside F1 increased thermogenesis and ameliorated insulin resistance specifically by promoting the browning of white adipose tissue in obese mice. Additionally, ginsenoside F1 improves norepinephrine-induced insulin resistance in adipocytes and hepatocytes, and shows a stronger mitochondria respiration ability than norepinephrine. These findings suggest that ginsenoside F1 is a promising lead compound in the improvement of insulin resistance.

Optogenetic activation of UCP1-dependent thermogenesis in brown adipocytes

Brown adipocytes are unique in that they expend energy and produce heat to maintain euthermia through expression of uncoupling protein-1 (UCP1). Given their propensity to stimulate weight loss and promote resistance to obesity, they are a compelling interventional target for obesity-related disorders. Here, we tested whether an optogenetic approach could be used to activate UCP1-dependent thermogenesis in brown adipocytes. We generated brown adipocytes expressing a bacterial-derived photoactivatable adenylyl cyclase (bPAC) that, upon blue light stimulation, increases UCP1 expression, fuel uptake and thermogenesis. This unique system allows for precise, chemical free, temporal control of UCP1-dependent thermogenesis, which can aid in our understanding of brown adipocyte biology and development of therapies that target obesity-related disorders.

Uncovering Actions of Type 3 Deiodinase in the Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD).

To evaluate the role of D3 in the progression of MAFLD in an animal model. Male/adult Sprague Dawley rats (n = 20) were allocated to a control group (2.93 kcal/g) and high-fat diet group (4.3 kcal/g). Euthanasia took place on the 28th week. D3 activity and expression, Uncoupling Protein 2 (UCP2) and type 1 deiodinase (D1) expression, oxidative stress status, mitochondrial, Krebs cycle and endoplasmic reticulum homeostasis in liver tissue were measured. We observed an increase in D3 activity/expression (p < 0.001) related to increased thiobarbituric acid reactive substances (TBARS) and carbonyls and diminished reduced glutathione (GSH) in the MAFLD group (p < 0.05). There was a D3-dependent decrease in UCP2 expression (p = 0.01), mitochondrial capacity, respiratory activity with increased endoplasmic reticulum stress in the MAFLD group (p < 0.001). Surprisingly, in an environment with lower T3 levels due to high D3 activity, we observed an augmented alpha-ketoglutarate dehydrogenase (KGDH) and glutamate dehydrogenase (GDH) enzymes activity (p < 0.05). Induced D3, triggered by changes in the REDOX state, decreases T3 availability and hepatic mitochondrial capacity. The Krebs cycle enzymes were altered as well as endoplasmic reticulum stress. Taken together, these results shed new light on the role of D3 metabolism in MAFLD.

UCP2-induced fatty acid synthase promotes NLRP3 inflammasome activation during sepsis.

Cellular lipid metabolism has been linked to immune responses; however, the precise mechanisms by which de novo fatty acid synthesis can regulate inflammatory responses remain unclear. The NLRP3 inflammasome serves as a platform for caspase-1–dependent maturation and secretion of proinflammatory cytokines. Here, we demonstrated that the mitochondrial uncoupling protein-2 (UCP2) regulates NLRP3-mediated caspase-1 activation through the stimulation of lipid synthesis in macrophages. UCP2-deficient mice displayed improved survival in a mouse model of polymicrobial sepsis. Moreover, UCP2 expression was increased in human sepsis. Consistently, UCP2-deficient mice displayed impaired lipid synthesis and decreased production of IL-1β and IL-18 in response to LPS challenge. In macrophages, UCP2 deficiency suppressed NLRP3-mediated caspase-1 activation and NLRP3 expression associated with inhibition of lipid synthesis. In UCP2-deficient macrophages, inhibition of lipid synthesis resulted from the downregulation of fatty acid synthase (FASN), a key regulator of fatty acid synthesis. FASN inhibition by shRNA and treatment with the chemical inhibitors C75 and cerulenin suppressed NLRP3-mediated caspase-1 activation and inhibited NLRP3 and pro–IL-1β gene expression in macrophages. In conclusion, our results suggest that UCP2 regulates the NLRP3 inflammasome by inducing the lipid synthesis pathway in macrophages. These results identify UCP2 as a potential therapeutic target in inflammatory diseases such as sepsis.

Light-emitting diode (LED) photobiomodulation regulates thermogenesis and lipogenesis markers in adipose tissue and improves anthropometric and metabolic parameters in obese mice

To evaluate the effects of Light-Emitting Diode (LED) irradiation on the expression of thermogenesis and lipogenesis-associated markers in adipose tissue and metabolic parameters of obese mice. Twenty-four male mice were divided into four groups:i) ST fed standard diet;ii) HCD fed hyperglycemic diet;iii) LED + I fed hyperglycemic diet and irradiated with LED in the interscapular region;iv) LED + A fed hyperglycemic diet and irradiated with LED in the abdominal region. The first phase of the study comprehended the induction of obesity for 12weeks. Next, the animals were submitted to six irradiation sessions (days 1, 3, 7, 10, 14, and 21) using a 660-nm LED (5.77J/cm2at 48,1mW/cm2). Anthropometric, biochemical, and histological parameters and the expression of thermogenesis and lipogenesis-associated markers were assessed in adipose tissue. There was diminished weight gain between the HCD and LED + A groups (ST: 0.37 ± 0.65; HCD: 3.10 ± 0.89; LED + I: -1.26 ± 0.83; LED + A: -2.07 ± 1.27g; p < 0.018). There was a 33.3% and 23.8% reduction in epidydimal adipose tissue weight and a 25% and 10.7% in the visceral adiposity for the LED + I and LED + A groups, respectively, when compared with HCD. There was adecreased accumulation of fat droplets in adipose tissue in LED + A and LED + I groups. Additionally, LED irradiation was associated with increased mRNA expression of uncoupling protein 1 (UCP1) in the brown adipose tissue (ST: 2.27 ± 0.19; HCD: 1.54 ± 0.12; LED + I: 2.44 ± 0.22; p = 0.014) and decreased fatty acid synthetase (FAS) expression in epidydimal adipose tissue (ST: 0.79 ± 0.13; HCD: 1.59 ± 0.13; LED + A: 0.85 ± 0.04; p = 0.0008). LED treatment improved anthropometric parameters, possibly associated with the histological alterations, thermogenesis and lipogenesis markers in white adipose tissue, and expression modulation in brown adipose tissue.

Novel pathogenesis of post-traumatic stress disorder studied in transgenic mice

Posttraumatic stress disorder (PTSD) is very common after exposure to trauma, mental stress or violence. Because objective biological markers for PTSD are lacking, exactly diagnosing PTSD is a challenge for clinical psychologists. In-depth research on the pathogenesis of PTSD is a key for solving this problem. In this work, we used male Thy1-YFP transgenic mice, in which neurons are fluorescently labeled, to research the effects of PTSD on neurons in vivo. We initially discovered that pathological stress associated with PTSD increased the activation of glycogen synthesis kinase-beta (GSK-3β) in neurons and induced the translocation of the transcription factor forkhead box-class O3a (FoxO3a) from the cytoplasm to the nucleus, which decreased the expression of uncoupling protein 2 (UCP2) and increased mitochondrial production of reactive oxygen species (ROS) to trigger neuronal apoptosis in the prefrontal cortex (PFC). Furthermore, the PTSD model mice showed increased freezing and anxiety-like behaviors and more severe decrease of memory and exploratory behavior. Additionally, leptin attenuated neuronal apoptosis by increasing the phosphorylation of signal transducer and activator of transcription 3 (STAT3), which further elevated the expression of UCP2 and inhibited the mitochondrial production of ROS induced by PTSD, thus reducing neuronal apoptosis and ameliorating PTSD-related behaviors. Our study is expected to promote the exploration of PTSD-related pathogenesis in neural cells and the clinical effectiveness of leptin for PTSD.

Thermogenic Capacity of Human Supraclavicular Brown Fat and Cold-Stimulated Brain Glucose Metabolism.

Human brain metabolism is susceptible to temperature changes. It has been suggested that the supraclavicular brown adipose tissue (BAT) protects the brain from these fluctuations by regulating heat production through the presence of uncoupling protein 1 (UCP-1). It remains unsolved whether inter-individual variation in the expression of UCP-1, which represents the thermogenic capacity of the supraclavicular BAT, is linked with brain metabolism during cold stress. Ten healthy human participants underwent 18F-FDG PET scanning of the brain under cold stimulus to determine brain glucose uptake (BGU). On a separate day, an excision biopsy of the supraclavicular fat-the fat proximal to the carotid arteries supplying the brain with warm blood-was performed to determine the mRNA expression of the thermogenic protein UCP-1. Expression of UCP-1 in supraclavicular BAT was directly related to the whole brain glucose uptake rate determined under cold stimulation (rho = 0.71, p = 0.03). In sub-compartmental brain analysis, UCP-1 expression in supraclavicular BAT was directly related to cold-stimulated glucose uptake rates in the hypothalamus, medulla, midbrain, limbic system, frontal lobe, occipital lobe, and parietal lobe (all rho ≥ 0.67, p < 0.05). These relationships were independent of body mass index and age. When analysing gene expressions of BAT secretome, we found a positive correlation between cold-stimulated BGU and DIO2. These findings provide evidence of functional links between brain metabolism under cold stimulation and UCP-1 and DIO2 expressions in BAT in humans. More research is needed to evaluate the importance of these findings in clinical outcomes, for instance, in examining the supporting role of BAT in cognitive functions under cold stress.

Neuro-immunohistochemical and molecular gene expression variations during hibernation and activity phases between Rana mascareniensis and Rana ridibunda

Low temperatures and the lack of food during the winter lead the marsh frog Rana ridibunda and the grass frog Rana mascareniensis to hibernate in order to survive. The present study aimed to investigate the cytoarchitecture of brain sub-regions affected by the thermal cycle's fluctuations during the hibernation and activity period, besides the regional distribution quantitative expression of Na(+)/K(+)-ATPase and Pax6 transcriptional factor, the molecular gene expressions of some heat shock proteins, uncoupling protein, and metallothionein. The two frog species were isolated from the field during summer and hibernation time in winter. During hibernation it was notable the destitution of degenerated, pyknotic and vasogenic neurons in different brain areas with high rate nearby the pallium. The immunohistochemical expression of Na+/ K+-ATPase and Pax 6 is decreased during hibernation in different brain sub-regions in the two species suggesting their tendency for energy conservation strategy during hibernation. Additionally, RT-qPCR recorded the up regulation of a number of heat shock protein genes during hibernation with sharing increase between two species for hsp90 besides and the non-significant expression in summer and hibernation periods for hsp47 for both species. Moreover, uncoupling protein (ucp1and ucp2) and metallothionein genes in olfactory bulb were with significant up regulation during the hibernation suggesting that these proteins possibly have a protective effect against reactive oxygen species ROS. So, brain adaptations to low temperature play a crucial role in coordinating stress responses. The present study shed light on the importance of the olfactory bulb in the thermoregulation and sensation of temperature elevations during the hibernation period and defended by the expression of heat shock proteins and uncoupling proteins preventing the cellular damage and proteins misfolding. Neuronal energy production and regeneration activities among amphibians are markedly reduced with decreasing body temperature.

Loss of transketolase promotes the anti-diabetic role of brown adipose tissues.

Transketolase (TKT), an enzyme in the non-oxidative branch of the pentose phosphate pathway (PPP), bi-directionally regulates the carbon flux between the PPP and glycolysis. Loss of TKT in adipose tissues decreased glycolysis and increased lipolysis and uncoupling protein-1 (UCP1) expression, protecting mice from high-fat diet-induced obesity. However, the role of TKT in brown adipose tissue (BAT)-dependent glucose homeostasis under normal chow diet remains to be elucidated. We found that TKT ablation increased levels of glucose transporter 4 (GLUT4), promoting glucose uptake and glycogen accumulation in BAT. Using the streptozotocin (STZ)-induced diabetic mouse model, we discovered that enhanced glucose uptake due to TKT deficiency in BAT contributed to decreasing blood glucose and weight loss, protecting mice from STZ-induced diabetes. Mechanistically, TKT deficiency decreased the level of thioredoxin-interacting protein, a known inhibitor for GLUT4, by decreasing NADPH and glutathione levels and inducing oxidative stress in BAT. Therefore, our data reveal a new role of TKT in regulating the anti-diabetic function of BAT as well as glucose homeostasis.

Effects of Intermittent Fasting on Hypothalamus-Pituitary-Thyroid Axis, Palatable Food Intake, and Body Weight in Stressed Rats.

Dietary regimens that are focused on diminishing total caloric intake and restricting palatable food ingestion are the most common strategies for weight control. However, restrictive diet therapies have low adherence rates in obese patients, particularly in stressed individuals. Moreover, food restriction downregulates the hypothalamic-pituitary-thyroid axis (HPT) function, hindering weight loss. Intermittent fasting (IF) has emerged as an option to treat obesity. We compared the effects of IF to an all-day feeding schedule on palatable diet (PD)-stress (S)-induced hyperphagia, HPT axis function, accumbal thyrotropin-releasing hormone (TRH), and dopamine D2 receptor expression in association with adipocyte size and PPARƔ coactivator 1α (PGC1α) and uncoupling protein 1 (UCP1) expression in stressed vs. non-stressed rats. After 5 weeks, S-PD rats showed an increased energy intake and adipocyte size, fewer beige cells, and HPT axis deceleration-associated low PGC1α and UCP1 expression, as well as decreased accumbal TRH and D2 expression. Interestingly, IF reversed those parameters to control values and increased the number of beige adipocytes, UCP1, and PGC1α mRNAs, which may favor a greater energy expenditure and a reduced body weight, even in stressed rats. Our results showed that IF modulated the limbic dopaminergic and TRHergic systems that regulate feeding and HPT axis function, which controls the metabolic rate, supporting this regimen as a suitable non-pharmacologic strategy to treat obesity, even in stressed individuals.

Smad4-mediated angiogenesis facilitates the beiging of white adipose tissue in mice

Beige adipocytes are thermogenic with high expression of uncoupling protein 1 in the white adipose tissue (WAT), accompanied by angiogenesis. Previous studies showed that Smad4 is important for angiogenesis. Here we studied whether endothelial Smad4-mediated angiogenesis is involved in WAT beiging. Inducible knockout of endothelial cell (EC) selective Smad4 (Smad4 iEC-KO) was achieved by using the Smad4 Floxp/floxp and Tie2 CreERT2 mice. Beige fat induction achieved by cold or adrenergic agonist, and angiogenesis were attenuated in WAT of Smad4 iEC-KO mice, with the less proliferation of ECs and adipogenic precursors. RNA sequencing of human ECs showed that Smad4 is involved in angiogenesis-related pathways. Knockdown of SMAD4 attenuated the upregulation of VEGFA, PDGFA, and angiogenesis invitro. Treatment of human ECs with palmitic acid-induced Smad1/5 phosphorylation and the upregulation of core endothelial genes. Our study shows that endothelial Smad4 is involved in WAT beiging through angiogenesis and the expansion of adipose precursors into beige adipocytes.

Anti-Inflammatory, Antioxidant, and WAT/BAT-Conversion Stimulation Induced by Novel PPAR Ligands: Results from Ex Vivo and In Vitro Studies.

Activation of peroxisome proliferator-activated receptors (PPARs) not only regulates multiple metabolic pathways, but mediates various biological effects related to inflammation and oxidative stress. We investigated the effects of four new PPAR ligands containing a fibrate scaffold-the PPAR agonists (1a (αEC50 1.0 μM) and 1b (γEC50 0.012 μM)) and antagonists (2a (αIC50 6.5 μM) and 2b (αIC50 0.98 μM, with a weak antagonist activity on γ isoform))-on proinflammatory and oxidative stress biomarkers. The PPAR ligands 1a-b and 2a-b (0.1-10 μM) were tested on isolated liver specimens treated with lipopolysaccharide (LPS), and the levels of lactate dehydrogenase (LDH), prostaglandin (PG) E2, and 8-iso-PGF2α were measured. The effects of these compounds on the gene expression of the adipose tissue markers of browning, PPARα, and PPARγ, in white adipocytes, were evaluated as well. We found a significant reduction in LPS-induced LDH, PGE2, and 8-iso-PGF2α levels after 1a treatment. On the other hand, 1b decreased LPS-induced LDH activity. Compared to the control, 1a stimulated uncoupling protein 1 (UCP1), PR-(PRD1-BF1-RIZ1 homologous) domain containing 16 (PRDM16), deiodinase type II (DIO2), and PPARα and PPARγ gene expression, in 3T3-L1 cells. Similarly, 1b increased UCP1, DIO2, and PPARγ gene expression. 2a-b caused a reduction in the gene expression of UCP1, PRDM16, and DIO2 when tested at 10 μM. In addition, 2a-b significantly decreased PPARα gene expression. A significant reduction in PPARγ gene expression was also found after 2b treatment. The novel PPARα agonist 1a might be a promising lead compound and represents a valuable pharmacological tool for further assessment. The PPARγ agonist 1b could play a minor role in the regulation of inflammatory pathways.

A lncRNA-encoded mitochondrial micropeptide exacerbates microglia-mediated neuroinflammation in retinal ischemia/reperfusion injury

As a common pathology of many ocular disorders such as diabetic retinopathy and glaucoma, retinal ischemia/reperfusion (IR) triggers inflammation and microglia activation that lead to irreversible retinal damage. The detailed molecular mechanism underlying retinal IR injury, however, remains poorly understood at present. Here we report the bioinformatic identification of a lncRNA 1810058I24Rik (181-Rik) that was shown to encode a mitochondrion-located micropeptide Stmp1. Its deficiency in mice protected retinal ganglion cells from retinal IR injury by attenuating the activation of microglia and the Nlrp3 inflammasome pathway. Moreover, its genetic knockout in mice or knockdown in primary microglia promoted mitochondrial fusion, impaired mitochondrial membrane potential, and reactive oxygen species (ROS) production, diminished aerobic glycolysis, and ameliorated inflammation. It appears that 181-Rik may trigger the Nlrp3 inflammasome activation by controlling mitochondrial functions through inhibiting expression of the metabolic sensor uncoupling protein 2 (Ucp2) and activating expression of the Ca2+ sensors S100a8/a9. Together, our findings shed new light on the molecular pathogenesis of retinal IR injury and may provide a fresh therapeutic target for IR-associated neurodegenerative diseases.