Activity In Adipocytes Research Articles

Ubiquitin ligase RNF20 coordinates sequential adipose thermogenesis with brown and beige fat-specific substrates

In mammals, brown adipose tissue (BAT) and inguinal white adipose tissue (iWAT) execute sequential thermogenesis to maintain body temperature during cold stimuli. BAT rapidly generates heat through brown adipocyte activation, and further iWAT gradually stimulates beige fat cell differentiation upon prolonged cold challenges. However, fat depot-specific regulatory mechanisms for thermogenic activation of two fat depots are poorly understood. Here, we demonstrate that E3 ubiquitin ligase RNF20 orchestrates adipose thermogenesis with BAT- and iWAT-specific substrates. Upon cold stimuli, BAT RNF20 is rapidly downregulated, resulting in GABPα protein elevation by controlling protein stability, which stimulates thermogenic gene expression. Accordingly, BAT-specific Rnf20 suppression potentiates BAT thermogenic activity via GABPα upregulation. Moreover, upon prolonged cold stimuli, iWAT RNF20 is gradually upregulated to promote de novo beige adipogenesis. Mechanistically, iWAT RNF20 mediates NCoR1 protein degradation, rather than GABPα, to activate PPARγ. Together, current findings propose fat depot-specific regulatory mechanisms for temporal activation of adipose thermogenesis.

Promote lipolysis in white adipocytes by magnetic hyperthermia therapy with Fe3O4 microsphere-doped hydrogel

Obesity has become an ongoing global crisis, since it increases the risks of cardiovascular disease, type 2 diabetes, fatty liver, cognitive decline, and some cancers. Adipose tissue is closely associated with the disorder of lipid metabolism. Several efforts have been made toward the modulation of lipid accumulation, but have been hindered by poor efficiency of cellular uptake, low safety, and uncertain effective dosage. Herein, we design an Fe3O4 microsphere-doped composite hydrogel (Fe3O4 microspheres @chitosan/β-glycerophosphate/collagen), termed as Fe3O4@Gel, as the magnetocaloric agent for magnetic hyperthermia therapy (MHT), aiming to promote lipolysis in white adipocytes. The experimental results show that the obtained Fe3O4@Gel displays a series of advantages, such as fast sol–gel transition, high biocompatibility, and excellent magneto-thermal performance. MHT, which is realized by Fe3O4@Gel subjected to an alternating magnetic field, leads to reduced lipid accumulation, lower triglyceride content, and increased mitochondrial activity in white adipocytes. This work shows that Fe3O4@Gel-mediated MHT can effectively promote lipolysis in white adipocytes in vitro, which provides a potential approach to treat obesity and associated metabolic disorders.

NG ,NG -Dimethylarginine Dimethylaminohydrolase 1 Expression Is Dispensable for Cold- or Diet-Induced Thermogenesis.

The strategy to activate thermogenic adipocytes has therapeutic potential to overcome obesity as they dissipate surplus energy as heat through various mechanisms. NG,NG-dimethylarginine dimethylaminohydrolases (DDAHs) are enzymes involved in the nitric oxide-protein kinase G signaling axis which increases thermogenic gene expression. However, the role of DDAHs in thermogenic adipocytes has not been elucidated. The adipocyte-specific Ddah1 knockout mice are generated by crossing Ddah1fl/fl mice with adiponectin Cre recombinase mice. Adipocyte-specific DDAH1 overexpressing mice are generated using adeno-associated virus-double-floxed inverse open reading frame (AAV-DIO) system. These mice are analyzed under basal, cold exposure, or high-fat diet (HFD) conditions. Primary inguinal white adipose tissue cells from adipocyte-specific Ddah1 knockout mice expressed comparable amounts of Ucp1 mRNA. Adipocyte-specific DDAH1 overexpressing mice do not exhibit enhanced activation of thermogenic adipocytes. In addition, when these mice are exposed to cold environment or fed an HFD, their body temperature/weight and thermogenesis-related gene and protein expressions are unchanged. These findings indicate that DDAH1 does not play a role in either cold- or diet-induced thermogenesis. Therefore, adipocyte targeting DDAH1 gene therapy for the treatment of obesity is unlikely to be effective.

The splicing factor SF3B1 is involved in brown adipocyte thermogenic activation

The ability of alternative splicing mechanisms to control gene expression is increasingly being recognized as relevant for adipose tissue function. The expression of SF3B1, a key component of the SF3B complex directly involved in spliceosome formation, was previously reported to be significantly induced in brown adipose tissue under cold-induced thermogenic activation. Here, we identify that noradrenergic cAMP-mediated thermogenic stimulation increases SF3B1 expression in brown and beige adipocytes. We further show that pladienolide-B, a drug that binds SF3B1 to inhibit pre-mRNA splicing by targeting the SF3B complex, down-regulates key components of the thermogenic machinery (e.g., UCP1 gene expression), differentially alters the expression of alternative splicing-regulated transcripts encoding molecular actors involved in the oxidative metabolism of brown adipocytes (e.g., peroxisome proliferator-activated receptor-gamma co-activator-alpha [PGC-1α] and cytochrome oxidase subunit 7a genes), and impairs the respiratory activity of brown adipocytes. Similar alterations were found in brown adipocytes with siRNA-mediated knockdown of SF3B1 protein levels. Our findings collectively indicate that SF3B1 is a key factor in the appropriate thermogenic activation of differentiated brown adipocytes. This work exemplifies the importance of splicing processes in adaptive thermogenesis and suggests that pharmacological tools, such as pladienolide-B, may be used to modulate brown adipocyte thermogenic activity.

GPR84-mediated signal transduction affects metabolic function by promoting brown adipocyte activity.

The G protein-coupled receptor 84 (GPR84), a medium-chain fatty acid receptor, has garnered attention because of its potential involvement in a range of metabolic conditions. However, the precise mechanisms underlying this effect remain elusive. Our study has shed light on the pivotal role of GPR84, revealing its robust expression and functional significance within brown adipose tissue (BAT). Mice lacking GPR84 exhibited increased lipid accumulation in BAT, rendering them more susceptible to cold exposure and displaying reduced BAT activity compared with their WT counterparts. Our in vitro experiments with primary brown adipocytes from GPR84-KO mice revealed diminished expression of thermogenic genes and reduced O2 consumption. Furthermore, the application of the GPR84 agonist 6-n-octylaminouracil (6-OAU) counteracted these effects, effectively reinstating the brown adipocyte activity. These compelling in vivo and in vitro findings converge to highlight mitochondrial dysfunction as the primary cause of BAT anomalies in GPR84-KO mice. The activation of GPR84 induced an increase in intracellular Ca2+ levels, which intricately influenced mitochondrial respiration. By modulating mitochondrial Ca2+ levels and respiration, GPR84 acts as a potent molecule involved in BAT activity. These findings suggest that GPR84 is a potential therapeutic target for invigorating BAT and ameliorating metabolic disorders.

Treatment with a new barbituric acid derivative suppresses diet-induced metabolic dysfunction and non-alcoholic fatty liver disease in mice

IntroductionNonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, often accompanied by obesity, diabetes, and increased risks of depression and anxiety. Currently, there are no FDA-approved drugs to treat NAFLD and its related systemic symptoms. Previously, we identified a new barbituric acid derivative (BA-5) that expressed effectiveness against fibrosis and drug-resistant hepatocellular carcinoma. AimsThis study investigated the potential of BA-5 against high-fat diet (HFD)-induced NAFLD and mood disorders in mice. Main methodsSix-weeks-old male C57BL/6 mice were fed with a 45 % HFD for 8 weeks to induce NAFLD and associated metabolic disorders. Mice were treated with a BA-5 and the therapeutic effects and the underlying molecular mechanisms were investigated. Key findingsAdministration of BA-5 significantly reduced serum levels of alanine aminotransferase (ALT), low-density lipoprotein (LDL), fatty acids (FA), and triglycerides (TG) in HFD-fed mice. BA-5 treatment decreased expressions of hepatic lipogenesis-related markers (acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and ATP-citrate lyase (ACLY)), increased fatty acid oxidation markers (carnitine palmitoyltransferase 1A (CPT1A) and acyl-CoA oxidase 1 (ACOX1)), and attenuated hepatic fat accumulation in HFD-fed mice. Moreover, HFD-induced adipocyte size enlargement and activation of lipolysis markers such as phosphorylated (p)-hormone-sensitive lipase (HSL) 565, p-HSL 660, and perilipin were inhibited in BA-5-treated mice. Notably, HFD-induced anxiety- and depression-like behaviors significantly improved in the BA-5 treated group through enhanced anti-inflammatory responses in the hippocampus. SignificanceThis study provides new insights into clinical therapeutic strategies of barbituric acid derivatives for HFD-induced NAFLD and associated mood disturbances.

Delivery of microRNA-423-5p by exosome from adipose-derived stem/stromal cells inhibits DVL3 to potentiate autologous fat graft survival through adipogenesis and inflammatory response.

Autologous fat grafting represents a reconstructive technique but is limited by unstable graft retention. Based on existing reports and bioinformatics prediction, we hypothesized that delivering exosomes from human adipose-derived stem/stromal cells (hADSC-Exo) would increase fat graft survival and further explore the mechanism. hADSC-Exo were extracted and identified. An autologous fat grafting model was established using donor and recipient mice, followed by hADSC-Exo treatment. hADSC-Exo promoted the retention of autologous fat grafts in mice, along with increased adipocyte activity, angiogenesis, and decreased inflammation in grafts. Moreover, hADSC-Exo potentiated the adipose differentiation of 3T3-L1 cells, enhanced the angiogenic and migratory capacity of human umbilical vein endothelial cells, and inhibited the inflammation and viability of RAW 264.7 cells. The therapeutic effect of hADSC-Exo on fat grafting was associated with the delivery of microRNA (miR)-423-5p. Deletion of miR-423-5p in Exo impaired the function of hADSC-Exo on fat retention. miR-423-5p bound to DVL3 to suppress DVL3 expression, and DVL3 deletion promoted adipose differentiation of 3T3-L1 cells. In conclusion, our findings further widen the theoretical basis of the clinical application of hADSC-Exo in autologous fat grafts.

Cimifugin inhibits adipogenesis and TNF-α-induced insulin resistance in 3T3-L1 cells.

To investigate the effects of cimifugin on adipogenesis and tumor necrosis factor (TNF-α)-induced insulin resistance (IR) and inflammation in 3T3-L1 adipocytes. 3T3-L1 adipocytes were treated with 3-isobutyl-1-methyl-xanthine, dexamethasone, and insulin or cimifugin and then Oil Red O staining and intracellular triglyceride content detection were performed to assess adipogenesis. Subsequently, after cimifugin treatment, TNF-α was used to induce IR and inflammation. The results showed that cimifugin reduced intracellular lipids accumulation of 3T3-L1 adipocytes. Cimifugin improved IR of 3T3-L1 adipocytes induced by TNF-α, as reflected in decreased adiponectin, GLUT-4, and IRS-1 mRNA and protein expression. Moreover, cimifugin reduced TNF-α-induced pro-inflammatory factors production and phospho-P65 expression, and MAPK pathway activation in the 3T3-L1 adipocytes. These findings suggested that cimifugin might be useful for the prevention and therapy of obesity-related IR and inflammation.

The combination of Ephedrae herba and coixol from Coicis semen attenuate adiposity via glucocorticoid receptor regulation

The enhanced therapeutic effects and mechanisms of certain herbal combination in various herbal prescriptions are mostly unclear. A combination of two herbs, namely Ephedrae herba (EH) and Coicis semen (CS), has been commonly prescribed for obesity. In our previous work, the combination of EH and CS was studied using network pharmacological approach to predict its pharmacological targets and in vitro experiments to evaluate its efficacy on obesity. Although we demonstrated enhanced anti-adiposity effects of the combination on matured adipocytes, the molecular mechanisms and contributing compounds underlying the effects of EH-CS combination on adiposity or adipogenesis were not fully elucidated. The current study adopted integrated bioinformatics analysis to precisely validate potential targets of EH-CS by screening differentially expressed genes (DEGs) of morbid obesity patients from NCBI gene expression omnibus (GEO). Based on the functional cluster analysis of down-regulated DEGs, the anti-adipogenesis mechanism of EH-CS combination was speculated with KEGG enrichment analysis. Furthermore, we investigated the combinational effects of EH and coixol, or stigmasterol, the two compounds in CS which were expected to have main beneficial effects in metabolic diseases. Moreover, distinct effect of the combination on transcriptional activity of glucocorticoid receptor (GR) was investigated using electrophoretic mobility shift assay (EMSA). The EH-CS combination was predicted to modulate down-regulated genes which are involved in KEGG pathways crucial to metabolic disease in morbidly obese individuals. The combination of EH with CS compounds significantly increased the phosphorylation of acetyl-coA carboxylase (ACC), AMP-activated protein kinase (AMPK), and protein kinase B (AKT) in 3T3-L1 cells and decreased intracellular lipid accumulation. The two CS compounds significantly increased the anti-adipogenesis/lipogenesis effects of EH by inhibiting the gene expression levels. Finally, the combination of EH and coixol inhibited dexamethasone-induced GR translocation to the nucleus and transcriptional binding activity in adipocytes. The combination of EH and CS could be considered a therapeutic strategy for treating metabolic diseases, including obesity.

Modulation of angiogenic switch in reprogramming browning and lipid metabolism in white adipocytes

Thermogenic activation via trans-and de novo browning of white adipocytes is a promising strategy to accelerate lipid metabolism for regulating obesity-related disorders. In this study, we investigated the intricate interplay between angiogenic regulation and browning in white adipocytes using the bioactive compound, resveratrol (Rsv). Rsv has previously been documented for its regulatory influence on the trans and de novo browning of white adipocytes. Our findings revealed that concurrent activation of angiogenesis is prerequisite for inducing browning within the microenvironment of white adipocytes when exposed to browning activators. Additionally, we observed a significant browning effect on white adipocytes when the local adipose tissue environment was prompted to undergo angiogenesis, notably facilitated by a proangiogenic molecule known as Vascular endothelial growth factor (VEGF). Intriguingly, this effect was reversed when angiogenesis was inhibited by treatment with the antiangiogenic agent thalidomide. Furthermore, the study revealed the role of VEGF in paracrine activation of white adipocytes resulting in the induction of browning in both 3T3-L1 cell lines and primary mouse white adipocytes. The cross-talk between angiogenesis and browning was found to be initiated via the transcriptional activation of Estrogen receptor α (ERα) triggering the VEGF/VEGFR2 signaling pathway leading to browning and a reconfiguration of lipid metabolism within adipocytes. In conclusion, this study sheds light on the intricate cross-talk between angiogenesis and browning of white adipocytes. Notably, the findings underscore the reciprocal relationship between these processes, wherein inhibition of one process exerts discernible effects on the other.

Exposure to Chlorpyrifos Alters Proliferation, Differentiation and Fatty Acid Uptake in 3T3-L1 Cells.

Organophosphorus pesticides (OPs) are important factors in the etiology of many diseases, including obesity and type 2 diabetes mellitus. The aim of this study was to investigate the effect of a representative of OPs, chlorpyrifos (CPF), on viability, proliferation, differentiation, and fatty acid uptake in 3T3-L1 cells. The effect of CPF exposure on preadipocyte proliferation was examined by the MTT, NR, and BrdU assays. The impact of CPF exposure on the differentiation of preadipocytes into mature adipocytes was evaluated by Oil Red O staining and RT-qPCR. The effect of CPF on free fatty acid uptake in adipocytes was assessed with the fluorescent dye BODIPY. Our experiments demonstrated that exposure to CPF decreased the viability of 3T3-L1 cells; however, it was increased when the cells were exposed to low concentrations of the pesticide. Exposure to CPF inhibited the proliferation and differentiation of 3T3-L1 preadipocytes. CPF exposure resulted in decreased lipid accumulation, accompanied by down-regulation of the two key transcription factors in adipogenesis: C/EBPα and PPARγ. Exposure to CPF increased basal free fatty acid uptake in fully differentiated adipocytes but decreased this uptake when CPF was added during the differentiation process. Increased free fatty acid accumulation in fully differentiated adipocytes may suggest that CPF leads to adipocyte hypertrophy, one of the mechanisms leading to obesity, particularly in adults. It can therefore be concluded that CPF may disturb the activity of preadipocytes and adipocytes, although the role of this pesticide in the development of obesity requires further research.

Protein PRDM16 and its importance for adipose tissue (literature review)

Currently, in Russia and in the world, there is an increase in the proportion of overweight and obese people among the population, which contributes to an increase in the number of socially significant diseases. Obesity is associated with the predominance of the proportion of fat mass in the component composition of the body. Based on this, increased attention is paid to a comprehensive study of the functioning of all types of human adipose tissue, which is necessary for the further use of this knowledge in the fight against obesity. This article provides an overview of the literature data on the structure and properties of the PRDM16 gene, the features of its functioning in brown, white and beige adipose tissue. The influence of the PRDM16 gene on the activation of brown adipogenesis and the formation of beige adipocytes in white adipose tissue, which contribute to increased heat production of cells by means of non-contractile thermogenesis and improvement of metabolic parameters of the body, is considered. Data on the role of PRDM16 protein in the treatment of obesity, type 2 diabetes mellitus and other human diseases associated with it are analyzed. The results on the methods of effective activation of brown and beige adipocytes and the use of these methods in the treatment of obesity are presented.

Multivalent insulin receptor activation using insulin-DNA origami nanostructures.

Insulin binds the insulin receptor (IR) and regulates anabolic processes in target tissues. Impaired IR signalling is associated with multiple diseases, including diabetes, cancer and neurodegenerative disorders. IRs have been reported to form nanoclusters at the cell membrane in several cell types, even in the absence of insulin binding. Here we exploit the nanoscale spatial organization of the IR to achieve controlled multivalent receptor activation. To control insulin nanoscale spatial organization and valency, we developed rod-like insulin-DNA origami nanostructures carrying different numbers of insulin molecules with defined spacings. Increasing the insulin valency per nanostructure markedly extended the residence time of insulin-DNA origami nanostructures at the receptors. Both insulin valency and spacing affected the levels of IR activation in adipocytes. Moreover, the multivalent insulin design associated with the highest levels of IR activation also induced insulin-mediated transcriptional responses more effectively than the corresponding monovalent insulin nanostructures. In an in vivo zebrafish model of diabetes, treatment with multivalent-but not monovalent-insulin nanostructures elicited a reduction in glucose levels. Our results show that the control of insulin multivalency and spatial organization with nanoscale precision modulates the IR responses, independent of the insulin concentration. Therefore, we propose insulin nanoscale organization as a design parameter in developing new insulin therapies.

THU547 Role Of NAD+ Synthesis Pathway In PARP Inhibitor Resistance

Abstract Disclosure: S. Challa: None. ADP-ribosylation is catalyzed by the poly(ADP-ribose) polymerase (PARP) family of enzymes consisting of 17 members that have distinct structural domains, activities, subcellular localizations, and functions. The catalytic activities of PARP enzymes are intimately tied to the synthesis of NAD+, which is consumed during ADPRylation reactions and, thus, must be regenerated. The intracellular salvage pathway utilizing nicotinamide (NAM) is the primary source of NAD+ in the cell. NAM is converted to nicotinamide mononucleotide (NMN) by NAMPT. Nicotinamide mononucleotide adenylyl transferases (NMNATs) catalyze the final step in the NAD+ salvage pathway, combining NMN and ATP to make NAD+. Three different NMNATs, each with a distinct subcellular localization, control the subcellular levels of NAD+ in each compartment: NMNAT-1 in the nucleus, NMNAT-2 is in the outer membrane of golgi, and NMNAT-3 in the mitochondria. We recently demonstrated that such compartment-specific NAD+ synthesis regulates the levels of ADP-ribosylation. Elevated levels of NMNAT-2, the cytosolic NAD+ synthase, reduces nuclear NAD+ levels and PARP1 activity in adipocytes and ovarian cancer cells. In the current study, we aim to delineate the role of compartmentalized synthesis of NAD+ in PARP inhibitor resistance in ovarian cancers. To identify these mechanisms, we generated ovarian cancer cells with acquired resistance to Niraparib, an FDA approved PARP inhibitor (NirR). We found that NirR cells have elevated levels of NAD+ biosynthesis. Moreover, treatment of parental cells with NAD+ precursors reduced the sensitivity to Niraparib while inhibition of NAD+ metabolism in NirR cells increased the sensitivity to Niraparib. Interestingly, the resistant cells have comparable levels of PARP1 activation to the parental cells. These data collectively suggests that NAD+ metabolism confers resistance to Niraparib without altering PARP1 activity. In line with this, NirR cells are sensitive to the effects of depletion of the cytosolic NAD+ biosynthesis, suggesting high NAD+ biosynthesis in NirR cells supports processes regulated by the cytosolic NAD+ which may drive the resistance phenotype. There is an urgent need to identify the mechanisms of resistance to PARP inhibitors to increase their clinical efficacy. This study identifies the NAD+ biosynthesis pathway as a key mechanism of PARP inhibitor resistance. Presentation: Thursday, June 15, 2023

A combination of commercial and traditional food-source-derived enzymatic treatment acts as a potential tool to produce functional yuzu (Citrus junos) powder

Enzymatic modifications have been applied in citrus to enhance their physicochemical and biological properties and reduce their bitterness. Notwithstanding, research on the combination of enzyme treatment of yuzu is lacking. In this study, yuzu was treated with a combination of isolated cellulase NY203, pectinase UF, and cellulase KN, and this enzymatic treatment was found to increase monosaccharide, naringenin, and hesperetin levels. In contrast, dietary fiber, cellulose, hemicellulose, lignin, and pectin levels were decreased. Moreover, the enzymes disintegrated the inner and outer surface structures and chemical bonding of yuzu, thus improving its solubility rate, water-holding capacity, oil-adsorption capacity, cholesterol-binding capacity, and water-swelling capacity. Furthermore, NY203 + UF + KN combination treatment reduced the bitterness of treated yuzu by 50 % compared with the control. Additionally, NY203 + UF + KN treatment yielded a 28 % decrease in lipid accumulation and two-fold higher lipolytic activity in 3T3L-1 adipocytes. These findings are potentially beneficial to the food/nutraceutical industries regarding functional yuzu powder production.

Influence of nutrition and food on sleep-is there evidence?

The influence of sleep disorders on metabolism, especially concerning obesity and diabetes, as well as obesity and obstructive sleep apnea, has been widely investigated. However, the effect of nutrition and the intake of certain foods on sleep has only recently gained attention. In recent years, there have been publications on intake of certain foods and certain diets regarding their influence on sleep, as well as activity of adipocytes and their effect on production of sleep hormones. Following PRISMA guidelines, we performed a PubMed search using the key words "sleep," "sleep disorders," "nutrition," "food," and "food intake" published from 2012 to 2022. We excluded by consensus all articles with diets and exercise programs or bariatric surgery for weight loss to treat sleep apnea, all articles on connections between sleep disorders and metabolic disorders, and articles concerning the influence of drugs on neuroactive substances. Of the 4155 publications revealed, 988 had nutrition, metabolism, and sleep as the primary topic of research. Of these 988 publications, only 26 fulfilled the content requirements concerning the influence of certain food and diets on sleep or sleep disorders, including the influence of the gastrointestinal system and adipocytes on sleep hormones. None of the investigations revealed clear evidence of an effect of a certain diet or food on sleep. Epidemiologic surveys suggest that shortened or fragmented sleep and chronotype in adults influence nutrition and fat metabolism. Additionally, there is evidence that adipocyte signaling influences neuronal mediators and hormones of the sleep-wake cycle. There is no evidence of a direct influence of certain nutrition or food intake on sleep. Obesity via adipocyte signaling may influence the sleep-wake cycle, though the molecular research on this topic is based on animal studies.

Inflammation-induced nitric oxide suppresses PPARα expression and function via downregulation of Sp1 transcriptional activity in adipocytes

The activation of peroxisome proliferator-activated receptor alpha (PPARα), a ligand-dependent transcription factor that regulates lipid oxidation-related genes, has been employed to treat hyperlipidemia. Emerging evidence indicates that Ppara gene expression decreases in adipose tissue under obese conditions; however, the underlying molecular mechanisms remain elusive. Here, we demonstrate that nitric oxide (NO) suppresses Ppara expression by regulating its promoter activity via suppression of specificity protein 1 (Sp1) transcriptional activity in adipocytes. NO derived from lipopolysaccharide (LPS) -activated macrophages or a NO donor (NOR5) treatment, suppressed Ppara mRNA expression in 10T1/2 adipocytes. In addition, Ppara transcript levels were reduced in the white adipose tissue (WAT) in both acute and chronic inflammation mouse models; however, such suppressive effects were attenuated via a nitric oxide synthase 2 (NOS2) inhibitor. Endoplasmic reticulum (ER) stress inhibitors attenuated the NO-induced repressive effects on Ppara gene expression in 10T1/2 adipocytes. Promoter mutagenesis and chromatin immunoprecipitation assays revealed that NO decreased the Sp1 occupancy in the proximal promoter regions of the Ppara gene, which might partially result from the reduced Sp1 expression levels by NO. This study delineated the molecular mechanism that modulates Ppara gene transcription upon NO stimulation in white adipocytes, suggesting a possible mechanism for the transcriptional downregulation of Ppara in WAT under obese conditions.

Brown Fat and Nutrition: Implications for Nutritional Interventions.

Brown and beige adipocytes are renowned for their unique ability to generate heat through a mechanism known as thermogenesis. This process can be induced by exposure to cold, hormonal signals, drugs, and dietary factors. The activation of these thermogenic adipocytes holds promise for improving glucose metabolism, reducing fat accumulation, and enhancing insulin sensitivity. However, the translation of preclinical findings into effective clinical therapies poses challenges, warranting further research to identify the molecular mechanisms underlying the differentiation and function of brown and beige adipocytes. Consequently, research has focused on the development of drugs, such as mirabegron, ephedrine, and thyroid hormone, that mimic the effects of cold exposure to activate brown fat activity. Additionally, nutritional interventions have been explored as an alternative approach to minimize potential side effects. Brown fat and beige fat have emerged as promising targets for addressing nutritional imbalances, with the potential to develop strategies for mitigating the impact of metabolic diseases. Understanding the influence of nutritional factors on brown fat activity can facilitate the development of strategies to promote its activation and mitigate metabolic disorders.

Fat and inflammation: adipocyte-myeloid cell crosstalk in atherosclerosis.

Adipose tissue inflammation has been implicated in various chronic inflammatory diseases and cancer. Perivascular adipose tissue (PVAT) surrounds the aorta as an extra layer and was suggested to contribute to atherosclerosis development. PVAT regulates the function of endothelial and vascular smooth muscle cells in the aorta and represent a reservoir for various immune cells which may participate in aortic inflammation. Recent studies demonstrate that adipocytes also express various cytokine receptors and, therefore, may directly respond to inflammatory stimuli. Here we will summarize current knowledge on immune mechanisms regulating adipocyte activation and the crosstalk between myeloid cells and adipocytes in pathogenesis of atherosclerosis.

Abstract 037: Neuromodulation Of Adipocyte Activity In Perivascular Adipose Tissue In Healthy Mice

Perivascular adipose tissue (PVAT) has emerged as a regulator of blood pressure by releasing anticontractile factors, which may be disrupted in disease. The production of adipocyte anticontractile factors is driven by norepinephrine (NE), a sympathetic neurotransmitter; however, the source of NE remains unknown. Here, we tested the hypothesis that neuronal innervation of PVAT stimulates adipocytes via NE. Mesenteric (mPVAT), aortic (aPVAT), and subcutaneous fat (sc) depots were studied in healthy male and female mice aged 8-12 weeks. Immunostaining with neuronal and vasculature markers was performed to assess anatomical evidence of neural innervation (n=3 region/sex). Adipocyte activity was studied in Adiponectin Cre;GCaMP 5g-tdT mice, which express the calcium indicator GCaMP5g in adipocytes (125-350 cells/group). Adipocytes were challenged with NE, a parasympathomimetic (bethanechol, 10uM, bath application), and nerve fibers were activated by electrical field stimulation (EFS; +100V, 0.1ms, 10 Hz). Immunolabeling data show that nerve fibers run adjacent to the larger blood vessels within adipose tissue, rather than radiating throughout. Stimulation with NE induced large responses (female: 0.91±0.73, 1.15±0.73, 1.45±0.9 dF/F 0 ; male: 0.75±0.57, 1.01±0.78, 0.73±0.53 dF/F 0 in aPVAT, mPVAT, sc, respectively). Both the parasympathomimetic and EFS induced minimal adipocyte responses compared to NE (% NE = [dF/F 0 bethanechol or EFS / dF/F 0 NE]*100%; bethanechol - female: 39.5%, 13.9%, 9.7%, male: 24.0%, 14.6%, 15.1% in aPVAT, mPVAT, sc, respectively; EFS - female: 31%, 12.2%, 9.7%, male: 28%, 13.9%, 13.7% in aPVAT, mPVAT, sc, respectively). These findings suggest that neural innervation within the PVAT, and functional regulation of adipocytes, is limited. Nerve fibers present within the PVAT are not the primary source of NE driving adipocyte production of anticontractile factors in the PVAT. Rather, this NE originates from other mechanisms including local production by non-neuronal cells or circulation of neurotransmitters.