The adipocyte supersystem of insulin and cAMP signaling

Visceral adipose tissue-derived extracellular vesicles promote stress susceptibility in obese mice via miR-140-5p

Obesity increases the risk of depression. Evidence shows that peripheral inflammation, glycemic dysregulation, and hyperactivity within the hypothalamic-pituitary-adrenal axis are implicated in both obesity and depression. In this study we investigated the impact of visceral adipose tissue (VAT), a crucial characteristic of obesity, on stress susceptibility in obese mice. Age-matched mice were fed with chow diet (CD) or high-fat diet (HFD), respectively, for 12 weeks. CD mice were deprived of VAT and received transplantation of VAT from HFD mice (TransHFD) or CD mice (TransCD). Extracellular vesicles (EVs) were prepared from VAT of CD or HFD mice, and intravenously injected (100 μg, 4 times in 2 weeks) in naïve mice or injected into hippocampus (5 μg, 4 times in 2 weeks) through implanted bilateral cannula. Depression-like behaviors were assessed 14 days after transplantation. We showed that HFD mice exhibited significantly higher body weight gain and impaired insulin and glucose tolerance, accompanied by increased stress susceptibility. Transplantation of VAT or VAT-derived EVs from HFD mice caused synaptic damage and promoted stress susceptibility in recipient mice. Through inhibiting miRNA biogenesis in the VAT and miRNA sequencing analysis, we demonstrated that miR-140-5p was significantly upregulated in both VAT-EVs and hippocampus of HFD mice. Overexpression of hippocampal miR-140-5p in naïve mice not only facilitated acute stress-induced depression-like behaviors, but also decreased hippocampal CREB-BDNF signaling cascade and synaptic plasticity. Conversely, knockdown of miR-140-5p in the VAT, VAT-EVs or hippocampus of HFD mice protected against acute stress, reducing stress susceptibility that were mediated via CREB-BDNF pathway. In summary, VAT-EVs or the cargo miRNAs in obese mice promote synaptic damage and stress susceptibility, providing potential therapeutic targets for metabolism-related affective disorders.

Vitamin D receptor signalling regulates the diet-driven metabolic shift during weaning

OBJECTIVE

Weaning in mammals is associated with a shift in the metabolism, driven by the differences in the macronutrient composition of milk and post-weaning diet. Milk has a higher fat content compared with the carbohydrate-enriched solid food. Malnutrition during this stage could affect this transition with long-term adverse effects. The role of micronutrients during this transition is not well understood.

METHODS

We used mice lacking a functional vitamin D receptor (VDR) to study the role of vitamin D signalling in the metabolic transition during weaning.

RESULTS

We demonstrate that after weaning, VDR knockout mice exhibit systemic energy deprivation and higher lipolysis in inguinal white adipose tissue, probably due to increased norepinephrine signalling via protein kinase A (PKA) and extracellular signalling-regulated kinase (ERK) pathways. The energy deprivation in vdr-/- mice is associated with defective liver glycogenolysis, characterized by increased expression of protein phosphatase-1 alpha and decreased glycogen phosphorylase activity. However, restoration of serum calcium and phosphate levels by a rescue diet is sufficient to restore energy metabolism in vdr-/- mice. Interestingly, maintaining a high-fat-containing milk-based diet post-weaning could prevent the onset of energy deprivation, liver glycogen storage defect, and adipose atrophy in these mice.

CONCLUSION

Our data show that vitamin D-signalling is essential for the adaptation of mice to the dietary shift from high-fat-containing milk to post-weaning carbohydrate-enriched diets. It also reveals a novel macronutrient-micronutrient interaction that shapes the metabolic flexibility of the individual based on the dietary composition of nutrients.

Endothelial insulin resistance induced by adrenomedullin mediates obesity-associated diabetes

Insulin resistance is a hallmark of obesity-associated type 2 diabetes. Insulin's actions go beyond metabolic cells and also involve blood vessels, where insulin increases capillary blood flow and delivery of insulin and nutrients. We show that adrenomedullin, whose plasma levels are increased in obese humans and mice, inhibited insulin signaling in human endothelial cells through protein-tyrosine phosphatase 1B-mediated dephosphorylation of the insulin receptor. In obese mice lacking the endothelial adrenomedullin receptor, insulin-induced endothelial nitric oxide-synthase activation and skeletal muscle perfusion were increased. Treating mice with adrenomedullin mimicked the effect of obesity and induced endothelial and systemic insulin resistance. Endothelial loss or blockade of the adrenomedullin receptor improved obesity-induced insulin resistance. These findings identify a mechanism underlying obesity-induced systemic insulin resistance and suggest approaches to treat obesity-associated type 2 diabetes.

bta-miR-484 Inhibits Bovine Intramuscular Adipogenesis by Regulating Mitotic Clonal Expansion via the MAP3K9/JNK/CCND1 Axis

Intramuscular fat (IMF) content is a critical indicator of the beef nutritional value and flavor. In this study, we focused on bta-miR-484, a microRNA that is differentially expressed during the adipogenic differentiation of bovine intramuscular adipocytes and is negatively correlated with the IMF content across different cattle breeds. Our findings demonstrate that bta-miR-484 inhibits adipogenic differentiation without altering the fatty acid composition of bovine intramuscular adipocytes. miRNA pull-down and dual-luciferase reporter assays confirmed that MAP3K9 is a target gene of bta-miR-484. Furthermore, bta-miR-484 suppresses the JNK signaling pathway by targeting MAP3K9, leading to decreased CCND1 expression, which impedes the mitotic clonal expansion (MCE) process and inhibits intramuscular adipocyte differentiation. In summary, this study uncovers a novel mechanism by which bta-miR-484 regulates bovine IMF content and provides the first exploration of MCE during intramuscular adipocyte adipogenic differentiation. These findings offer valuable theoretical insights into beef cattle breeding and molecular improvements.

The relevance of the heme oxygenase system in alleviating diabetes-related hormonal and metabolic disorders

Heme oxygenase (HO) is an enzyme that catalyzes heme degradation. HO dysfunction is linked to various pathological conditions, including diabetes. Results of animal studies indicate that HO expression and activity are downregulated in experimentally induced diabetes. This is associated with severe hormonal and metabolic disturbances. However, these pathological changes have been shown to be reversed by therapy with HO activators. In animals with experimentally induced diabetes, HO was upregulated by genetic manipulation or by pharmacological activators such as hemin and cobalt protoporphyrin. Induction of HO alleviated elevated blood glucose levels and improved insulin action, among other effects. This effect resulted from beneficial changes in the main insulin-sensitive tissues, i.e., the skeletal muscle, the liver, and the adipose tissue. The action of HO activators was due to positive alterations in pivotal signaling molecules and regulatory enzymes. Furthermore, diabetes-related oxidative and inflammatory stress was reduced due to HO induction. HO upregulation was effective in various animal models of type 1 and type 2 diabetes. These data suggest the possibility of testing HO activators as a potential tool for alleviating hormonal and metabolic disorders in people with diabetes.

The role of compartmentalized β-AR/cAMP signaling in the regulation of lipolysis in white and brown adipocytes

White and brown adipocytes are central mediators of lipid metabolism and thermogenesis, respectively. Their function is tightly regulated by all three β-adrenergic receptor (β-AR) subtypes which are coupled to the production of the second messenger 3',5'-cyclic adenosine monophosphate (cAMP). While known for decades in other cell types, compartmentation of adipocyte β-AR/cAMP signaling by spatial organization of the pathway and by cAMP degrading phosphodiesterases (PDEs) as well as its role in the regulation of lipolysis is only beginning to emerge. Here, we provide a short overview of recent findings which shed light on compartmentalized signaling using live cell imaging of cAMP in adipocytes and discuss possible future directions of research which could open up new avenues for the treatment of metabolic disorders.

Fibroblast growth factor 1 (FGF1) improves glucose homeostasis, modulates gut microbial composition, and reduces inflammatory responses in rainbow trout (Oncorhynchus mykiss) fed a high-fat diet

High-fat diets (HFDs) are widely used in aquaculture due to their lipid and protein-conserving effects, thereby reducing feed costs. However, prolonged feeding of HFD often leads to metabolic disorders in fish, such as disruption of hepatic lipid homeostasis, liver injury, and disruption of glucose homeostasis. Fibroblast growth factor 1 (FGF1) plays an essential role in controlling glucose levels in the body and dampening immune reactions. However, its impact on teleosts remains poorly researched. The therapeutic potential of recombinant FGF1 (rFGF1) was examined in a 6-week culture experiment involving rainbow trout (Oncorhynchus mykiss) that were fed an HFD. The results revealed that rFGF1 significantly reduced serum glucose levels and hepatic PEPCK and G6PC activities, but improved hepatic glycogen (P < 0.05), compared to the HFD + PBS group. Further experiments indicated that the inhibitory effect of rFGF1 on hepatic gluconeogenesis was mediated by the cAMP signaling pathway and was dependent on the high expression of PDE4D. In addition, rFGF1 increased hepatic glycogen content, which involves the AKT-GSK3β axis. Despite this increase, rFGF1 did not lead to glycogen storage disease, as shown by reduced hepatic inflammation as a result of decreased GOT (glutamic oxaloacetic transaminase), GPT (glutamic pyruvic transaminase), and elevated SOD (superoxide dismutase) in the rFGF1-treated group, accompanied by decreased il-1β, il-6, and xbp-1, and elevated nrf2 and number of hepatocyte autophagosomes. Alterations in gut microbes and short-chain fatty acids (SCFAs) were noted, indicating that rFGF1 caused a notable rise in intestinal Lactobacillus, acetic acid, and butyric acid levels. This study investigated the molecular mechanisms of rFGF1 on glucose metabolism and inflammatory responses in an HFD-fed rainbow trout model, providing new insights to improve the regulation of glucose metabolism in carnivorous fish.

Circulating perturbation of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) is associated to cardiac remodeling and NLRP3 inflammasome in cardiovascular patients with insulin resistance risk

Lipidome perturbation occurring during meta-inflammation is associated to left ventricle (LV) remodeling though the activation of the NLRP3 inflammasome, a key regulator of chronic inflammation in obesity-related disorders. Little is known about phosphatidylcholine (PC) and phosphatidylethanolamine (PE) as DAMP-induced NLRP3 inflammasome. Our study is aimed to evaluate if a systemic reduction of PC/PE molar ratio can affect NLRP3 plasma levels in cardiovascular disease (CVD) patients with insulin resistance (IR) risk. Forty patients from IRCCS Policlinico San Donato were enrolled, and their blood samples were drawn before heart surgery. LV geometry measurements were evaluated by echocardiography and clinical data associated to IR risk were collected. PC and PE were quantified by ESI-MS/MS. Circulating NLRP3 was quantified by an ELISA assay. Our results have shown that CVD patients with IR risk presented systemic lipid impairment of PC and PE species and their ratio in plasma was inversely associated to NLRP3 levels. Interestingly, CVD patients with IR risk presented LV changes directly associated to increased levels of NLRP3 and a decrease in PC/PE ratio in plasma, highlighting the systemic effect of meta-inflammation in cardiac response. In summary, PC and PE can be considered bioactive mediators associated to both the NLRP3 and LV changes in CVD patients with IR risk.

An adipoincretin effect links adipostasis with insulin secretion

The current paradigm for the insulin system focuses on the phenomenon of glucose-stimulated insulin secretion and insulin action on blood glucose control. This historical glucose-centric perspective may have introduced a conceptual bias in our understanding of insulin regulation. A body of evidence demonstrating that in vivo variations in blood glucose and insulin secretion can be largely dissociated motivated us to reconsider the fundamental design of the insulin system as a control system for metabolic homeostasis. Here, we propose that a minimal glucose-centric model does not accurately describe the physiological behavior of the insulin system and propose a new paradigm focusing on the effects of incretins, arguing that under fasting conditions, insulin is regulated by an adipoincretin effect.

Myokines: metabolic regulation in obesity and type 2 diabetes

Skeletal muscle plays a vital role in the regulation of systemic metabolism, partly through its secretion of endocrine factors which are collectively known as myokines. Altered myokine levels are associated with metabolic diseases, such as type 2 diabetes (T2D). The significance of interorgan crosstalk, particularly through myokines, has emerged as a fundamental aspect of nutrient and energy homeostasis. However, a comprehensive understanding of myokine biology in the setting of obesity and T2D remains a major challenge. In this review, we discuss the regulation and biological functions of key myokines that have been extensively studied during the past two decades, namely interleukin 6 (IL-6), irisin, myostatin (MSTN), growth differentiation factor 11 (GDF11), fibroblast growth factor 21 (FGF21), apelin, brain-derived neurotrophic factor (BDNF), meteorin-like (Metrnl), secreted protein acidic and rich in cysteine (SPARC), β-aminoisobutyric acid (BAIBA), Musclin, and Dickkopf 3 (Dkk3). Related to these, we detail the role of exercise in myokine expression and secretion together with their contributions to metabolic physiology and disease. Despite significant advancements in myokine research, many myokines remain challenging to measure accurately and investigate thoroughly. Hence, new research techniques and detection methods should be developed and rigorously tested. Therefore, developing a comprehensive perspective on myokine biology is crucial, as this will likely offer new insights into the pathophysiological mechanisms underlying obesity and T2D and may reveal novel targets for therapeutic interventions.

Adipocyte PI3K links adipostasis with baseline insulin secretion at fasting through an adipoincretin effect

Insulin-PI3K signaling controls insulin secretion. Understanding this feedback mechanism is crucial for comprehending how insulin functions. However, the role of adipocyte insulin-PI3K signaling in controlling insulin secretion in vivo remains unclear. Using adipocyte-specific PI3Kα knockout mice (PI3KαAdQ) and a panel of isoform-selective PI3K inhibitors, we show that PI3Kα and PI3Kβ activities are functionally redundant in adipocyte insulin signaling. PI3Kβ-selective inhibitors have no effect on adipocyte AKT phosphorylation in control mice but blunt it in adipocytes of PI3KαAdQ mice, demonstrating adipocyte-selective pharmacological PI3K inhibition in the latter. Acute adipocyte-selective PI3K inhibition increases serum free fatty acid (FFA) and potently induces insulin secretion. We name this phenomenon the adipoincretin effect. The adipoincretin effect operates in fasted mice with increasing FFA and decreasing glycemia, indicating that it is not primarily a control system for blood glucose. This feedback control system defines the rates of adipose tissue lipolysis and chiefly controls basal insulin secretion during fasting.

Olodaterol promotes thermogenesis in brown adipocytes via regulation of the β2-AR/cAMP/PKA signaling pathway

The escalating incidence of metabolic pathologies such as obesity and diabetes mellitus underscores the imperative for innovative therapeutics targeting lipid metabolism modulation. Within this context, augmenting thermogenic processes in adipose cells emerges as a viable therapeutic approach. Given the limitations of previous β3-adrenergic receptor (β3-AR) agonist treatments in human diseases, there is an increasing focus on therapies targeting the β2-adrenergic receptor (β2-AR). Olodaterol (OLO) is a potent β2-AR agonist that is a potential novel pharmacological candidate in this area. Our study explores the role and underlying mechanisms of OLO in enhancing brown adipose thermogenesis, providing robust evidence from in vitro and in vivo studies. OLO demonstrated a dose-dependent enhancement of lipolysis, notably increasing the expression of Uncoupling Protein 1 (UCP1) and raising the rate of oxygen consumption in primary brown adipocytes. This suggests a significant increase in thermogenic potential and energy expenditure. The administration of OLO to murine models noticeably enhanced cold-induced nonshivering thermogenesis. OLO elevated UCP1 expression in the brown adipose tissue of mice. Furthermore, it promoted brown adipocyte thermogenesis by activating the β2-AR/cAMP/PKA signaling cascades according to RNA sequencing, western blotting, and molecular docking analysis. This investigation underscores the therapeutic potential of OLO for metabolic ailments and sheds light on the intricate molecular dynamics of adipocyte thermogenesis, laying the groundwork for future targeted therapeutic interventions in human metabolic disorders.

Activation of GPR81 by lactate drives tumour-induced cachexia

Cachexia affects 50-80% of patients with cancer and accounts for 20% of cancer-related death, but the underlying mechanism driving cachexia remains elusive. Here we show that circulating lactate levels positively correlate with the degree of body weight loss in male and female patients suffering from cancer cachexia, as well as in clinically relevant mouse models. Lactate infusion per se is sufficient to trigger a cachectic phenotype in tumour-free mice in a dose-dependent manner. Furthermore, we demonstrate that adipose-specific G-protein-coupled receptor (GPR)81 ablation, similarly to global GPR81 deficiency, ameliorates lactate-induced or tumour-induced adipose and muscle wasting in male mice, revealing adipose GPR81 as the major mediator of the catabolic effects of lactate. Mechanistically, lactate/GPR81-induced cachexia occurs independently of the well-established protein kinase A catabolic pathway, but it is mediated by a signalling cascade sequentially activating Gi-Gβγ-RhoA/ROCK1-p38. These findings highlight the therapeutic potential of targeting GPR81 for the treatment of this life-threatening complication of cancer.

The association between the AIP and undiagnosed diabetes in ACS patients with different body mass indexes and LDL-C levels: findings from the CCC-ACS project

BACKGROUND

The atherogenic index of plasma (AIP) has been demonstrated to be significantly associated with the incidence of prediabetes and diabetes. This study aimed to investigate the association between the AIP and undiagnosed diabetes in acute coronary syndrome (ACS) patients.

METHODS

Among 113,650 ACS patients treated with coronary angiography at 240 hospitals in the Improving Care for Cardiovascular Disease in China-ACS Project from 2014 to 2019, 11,221 patients with available clinical and surgical information were included. We analyzed these patients' clinical characteristics after stratification according to AIP tertiles, body mass index (BMI) and low-density lipoprotein cholesterol (LDL-C) levels.

RESULTS

The AIP was independently associated with a greater incidence of undiagnosed diabetes. The undiagnosed diabetes was significantly greater in the T3 group than in the T1 group after adjustment for confounders [T3 OR 1.533 (1.199-1.959) p < 0.001]. This relationship was consistent within normal weight patients and patients with an LDL-C level ≥ 1.8 mmol/L. In overweight and obese patients, the AIP was significantly associated with the incidence of undiagnosed diabetes as a continuous variable after adjustment for age, sex, and BMI but not as a categorical variable. The area under the receiver operating characteristic curve (AUC) of the AIP score, triglyceride (TG) concentration, and HDL-C concentration was 0.601 (0.581-0.622; p < 0.001), 0.624 (0.603-0.645; p < 0.001), and 0.493 (0.472-0.514; p = 0.524), respectively. A nonlinear association was found between the AIP and the incidence of undiagnosed diabetes in ACS patients (p for nonlinearity < 0.001), and this trend remained consistent between males and females. The AIP may be a negative biomarker associated with undiagnosed diabetes ranging from 0.176 to 0.738.

CONCLUSION

The AIP was significantly associated with the incidence of undiagnosed diabetes in ACS patients, especially in those with normal weight or an LDL-C level ≥ 1.8 mmol/L. A nonlinear relationship was found between the AIP and the incidence of undiagnosed diabetes, and this trend was consistent between male and female patients. The AIP may be a negative biomarker associated with undiagnosed diabetes and ranges from 0.176 to 0.738.

Impact of cold exposure on life satisfaction and physical composition of soldiers

This article has been retracted.

Transcriptional determinants of lipid mobilization in human adipocytes

Defects in adipocyte lipolysis drive multiple aspects of cardiometabolic disease, but the transcriptional framework controlling this process has not been established. To address this, we performed a targeted perturbation screen in primary human adipocytes. Our analyses identified 37 transcriptional regulators of lipid mobilization, which we classified as (i) transcription factors, (ii) histone chaperones, and (iii) mRNA processing proteins. On the basis of its strong relationship with multiple readouts of lipolysis in patient samples, we performed mechanistic studies on one hit, ZNF189, which encodes the zinc finger protein 189. Using mass spectrometry and chromatin profiling techniques, we show that ZNF189 interacts with the tripartite motif family member TRIM28 and represses the transcription of an adipocyte-specific isoform of phosphodiesterase 1B (PDE1B2). The regulation of lipid mobilization by ZNF189 requires PDE1B2, and the overexpression of PDE1B2 is sufficient to attenuate hormone-stimulated lipolysis. Thus, our work identifies the ZNF189-PDE1B2 axis as a determinant of human adipocyte lipolysis and highlights a link between chromatin architecture and lipid mobilization.

Anti-oxidant effects of herbal residue from Shengxuebao mixture on heat-stressed New Zealand rabbits

Heat stress can lead to hormonal imbalances, weakened immune system, increased metabolic pressure on the liver, and ultimately higher animal mortality rates. This not only seriously impairs the welfare status of animals, but also causes significant economic losses to the livestock industry. Due to its rich residual bioactive components and good safety characteristics, traditional Chinese medicine (TCM) residue is expected to become a high-quality feed additive with anti-oxidative stress alleviating function. This study focuses on the potential of Shengxuebao mixture herbal residue (SXBR) as an anti-heat stress feed additive. Through the UPLC (ultra performance liquid chromatography) technology, the average residue rate of main active ingredients from SXBR were found to be 25.39%. SXBR were then added into the basal diet of heat stressed New Zealand rabbits at the rates of 5% (SXBRl), 10% (SXBRm) and 20% (SXBRh). Heat stress significantly decreased the weight gain, as well as increased neck and ear temperature, drip loss in meat, inflammation and oxidative stress. Also, the hormone levels were disrupted, with a significant increase in serum levels of CA, COR and INS. After the consumption of SXBR in the basal diet for 3 weeks, the weight of New Zealand rabbits increased significantly, and the SXBRh group restored the redness value of the meat to a similar level as the control group. Furthermore, the serum levels T3 thyroid hormone in the SXBRh group and T4 thyroid hormone in the SXBRm group increased significantly, the SXBRh group showed a significant restoration in inflammation markers (IL-1β, IL-6, and TNF-α) and oxidative stress markers (total antioxidant capacity, HSP-70, MDA, and ROS) levels. Moreover, the real-time fluorescence quantitative PCR analysis found that, the expression levels of antioxidant genes such as Nrf2, HO-1, NQO1, and GPX1 were significantly upregulated in the SXBRh group, and the expression level of the Keap1 gene was significantly downregulated. Additionally, the SXBRm group showed significant upregulation in the expression levels of HO-1 and NQO1 genes. Western blot experiments further confirmed the up-regulation of Nrf2, Ho-1 and NQO1 proteins. This study provides a strategy for the utilization of SXBR and is of great significance for the green recycling of the TCM residues, improving the development of animal husbandry and animal welfare.

ITGB1 alleviates osteoarthritis by inhibiting cartilage inflammation and apoptosis via activating cAMP pathway

OBJECTIVE

We aimed to screen novel biomarkers for osteoarthritis (OA) using bioinformatic methods and explore its regulatory mechanism in OA development.

METHODS

Differentially expressed genes were screened out from GSE98918 and GSE82107 datasets. Protein-protein interaction network and enrichment analysis were employed to search for hub gene and regulatory pathway. Hematoxylin-eosin, Safranin O-Fast green staining, and immunohistochemistry were performed to assess pathological damage. TNF-α, IL-1β, and IL-6 concentrations were determined by enzyme-linked immunosorbent assay. Real-time quantitative PCR was applied to verify expression of hub genes in OA model. The expression of key protein and pathway proteins was determined by western blot. Furthermore, Cell Counting Kit-8 and flow cytometry were conducted to explore the role of hub gene in chondrocytes.

RESULTS

We identified 6 hub genes of OA, including ITGB1, COL5A1, COL1A1, THBS2, LAMA1, and COL12A1, with high prediction value. ITGB1 was screened as a pivotal regulator of OA and cAMP pathway was selected as the key regulatory pathway. ITGB1 was down-regulated in OA model. ITGB1 overexpression attenuated pathological damage and apoptosis in OA rats with the reduced levels of TNF-α, IL-1β and IL-6. ITGB1 overexpression activated cAMP pathway in vivo and vitro models. In vitro model, ITGB1 overexpression promoted cell viability, while inhibited apoptosis. ITGB1 overexpression also caused a decrease of TNF-α, IL-1β, and IL-6 concentrations. cAMP pathway inhibitor reversed the positive effect of ITGB1 on OA cell model.

CONCLUSION

ITGB1 is a novel biomarker for OA, which inhibits OA development by activating the cAMP pathway.

Effects of cortisol, epinephrine, and bisphenol contaminants on the transcriptional landscape of marine mammal blubber

Top ocean predators such as marine mammals are threatened by intensifying anthropogenic activity, and understanding the combined effects of multiple stressors on their physiology is critical for conservation efforts. We investigated potential interactions between stress hormones and bisphenol contaminants in a model marine mammal, the northern elephant seal (NES). We exposed precision-cut adipose tissue slices (PCATS) from blubber of weaned NES pups to cortisol (CORT), epinephrine (EPI), bisphenol A (BPA), bisphenol S (BPS), or their combinations (CORT-EPI, BPA-EPI, and BPS-EPI) ex vivo and identified hundreds of genes that were differentially regulated in response to these treatments. CORT altered expression of genes associated with lipolysis and adipogenesis, whereas EPI and CORT-EPI-regulated genes were associated with responses to hormones, lipid and protein turnover, immune function, and transcriptional and epigenetic regulation of gene expression, suggesting that EPI has wide-ranging and prolonged impacts on the transcriptional landscape and function of blubber. Bisphenol treatments alone had a weak impact on gene expression compared with stress hormones. However, the combination of EPI with bisphenols altered expression of genes associated with inflammation, cell stress, DNA damage, regulation of nuclear hormone receptor activity, cell cycle, mitochondrial function, primary ciliogenesis, and lipid metabolism in blubber. Our results suggest that CORT, EPI, bisphenols, and their combinations impact cellular, immune, and metabolic homeostasis in marine mammal blubber, which may affect the ability of marine mammals to sustain prolonged fasting during reproduction and migration, renew tissues, and mount appropriate responses to immune challenges and additional stressors.

Crosstalk between corepressor NRIP1 and cAMP signaling on adipocyte thermogenic programming

OBJECTIVES

Nuclear receptor interacting protein 1 (NRIP1) suppresses energy expenditure via repression of nuclear receptors, and its depletion markedly elevates uncoupled respiration in mouse and human adipocytes. We tested whether NRIP1 deficient adipocytes implanted into obese mice would enhance whole body metabolism. Since β-adrenergic signaling through cAMP strongly promotes adipocyte thermogenesis, we tested whether the effects of NRIP1 knock-out (NRIP1KO) require the cAMP pathway.

METHODS

NRIP1KO adipocytes were implanted in recipient high-fat diet (HFD) fed mice and metabolic cage studies conducted. The Nrip1 gene was disrupted by CRISPR in primary preadipocytes isolated from control vs adipose selective GsαKO (cAdGsαKO) mice prior to differentiation to adipocytes. Protein kinase A inhibitor was also used.

RESULTS

Implanting NRIP1KO adipocytes into HFD fed mice enhanced whole-body glucose tolerance by increasing insulin sensitivity, reducing adiposity, and enhancing energy expenditure in the recipients. NRIP1 depletion in both control and GsαKO adipocytes was equally effective in upregulating uncoupling protein 1 (UCP1) and adipocyte beiging, while β-adrenergic signaling by CL 316,243 was abolished in GsαKO adipocytes. Combining NRIP1KO with CL 316,243 treatment synergistically increased Ucp1 gene expression and increased the adipocyte subpopulation responsive to beiging. Estrogen-related receptor α (ERRα) was dispensable for UCP1 upregulation by NRIPKO.

CONCLUSIONS

The thermogenic effect of NRIP1 depletion in adipocytes causes systemic enhancement of energy expenditure when such adipocytes are implanted into obese mice. Furthermore, NRIP1KO acts independently but cooperatively with the cAMP pathway in mediating its effect on adipocyte beiging.

Estrogen prevents age-dependent beige adipogenesis failure through NAMPT-controlled ER stress pathway

Thermogenic beige adipocytes are recognized as potential therapeutic targets for combating metabolic diseases. However, the metabolic advantages they offer are compromised with aging. Here, we show that treating mice with estrogen (E2), a hormone that decreases with age, to mice can counteract the aging- related decline in beige adipocyte formation when subjected to cold, while concurrently enhancing energy expenditure and improving glucose tolerance. Mechanistically, we find that nicotinamide phosphoribosyltranferase (NAMPT) plays a pivotal role in facilitating the formation of E2-induced beige adipocytes, which subsequently suppresses the onset of age-related ER stress. Furthermore, we found that targeting NAMPT signaling, either genetically or pharmacologically, can restore the formation of beige adipocytes by increasing the number of perivascular adipocyte progenitor cells. Conversely, the absence of NAMPT signaling prevents this process. In conclusion, our findings shed light on the mechanisms governing the age-dependent impairment of beige adipocyte formation and underscore the E2-NAMPT controlled ER stress as a key regulator of this process.

Highlights

Estrogen restores beige adipocyte failure along with improved energy metabolism in old mice.Estrogen enhances the thermogenic gene program by mitigating age-induced ER stress.Estrogen enhances the beige adipogenesis derived from SMA+ APCs.Inhibiting the NAMPT signaling pathway abolishes estrogen-promoted beige adipogenesis.

Activation of the cGAS-STING pathway by a mitochondrial DNA-targeted emissive rhodium(iii) metallointercalator

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon (STING) pathway is a key mediator of innate immunity involved in cancer development and treatment. The roles of mitochondrial DNA (mtDNA) in cancer immunotherapy have gradually emerged. Herein, we report a highly emissive rhodium(iii) complex (Rh-Mito) as the mtDNA intercalator. Rh-Mito can specifically bind to mtDNA to cause the cytoplasmic release of mtDNA fragments to activate the cGAS-STING pathway. Moreover, Rh-Mito activates the mitochondrial retrograde signaling by disturbing the key metabolites involved in epigenetic modifications, which alters the nuclear genome methylation landscape to influence the expression of genes related to immune signaling pathways. Finally, we demonstrate that ferritin-encapsulated Rh-Mito elicits potent anticancer activities and evokes intense immune responses in vivo by intravenous injection. Overall, we report for the first time that small molecules targeting mtDNA can activate the cGAS-STING pathway, which gives insights into the development of biomacromolecule-targeted immunotherapeutic agents.

Fuziline Ameliorates Glucose and Lipid Metabolism by Activating Beta Adrenergic Receptors to Stimulate Thermogenesis

Radix aconiti carmichaeli is a widely used traditional Chinese medicine that has been found to be effective in treating cardiovascular diseases and metabolic disorders. Patients with these diseases often experience a heat generation disorder, which is characterized by chilliness and can worsen the progression of the disease. This study established an in vitro screening model combining the examination of cellular mitochondrial membrane potential and mitochondrial temperature to screen drugs with thermogenic activity. After differentiation and determination of the content of characteristic metabolites of the drug-containing serum blood components, it was found that Fuziline (FZL) is the key thermogenic property in Radix aconiti carmichaeli, responsible for its thermogenic effects with a high relative importance of 33%. Experiments were conducted to evaluate the thermogenic activity of Radix aconiti carmichaeli and FZL in vivo by assessing temperature changes in various organs, including the rectum, liver, and brown adipose tissue. Moreover, the effects of intracellular β3-adrenergic receptor (β3-AR) agonistic effects were evaluated using transient β3-AR transfection and dual-luciferase assay systems. The molecular mechanism by which FZL promotes thermogenesis and improves mitochondrial function was investigated by verifying the β-adrenergic receptors (β-AR) downstream signaling pathway. The results suggest that FZL activates β-AR nonselectively, which in turn activates the downstream cAMP-PKA signaling pathway and leads to an increase in liver glycogenolysis and triglyceride hydrolysis, accompanied by enhancing mitochondrial energy metabolism. Consequently, the liver and brown adipose tissue receive energy to generate heat. In summary, these findings provide insight into the therapeutic application of Radix aconiti carmichaeli for metabolic disorders associated with heat generation disorders.