Gonadal White Adipose Tissue Research Articles

1888-P: Activation of Myocardial Mitochondrial Akt1 Remotely Modulated Body Composition and Adiposity through LXR/RXR Signaling

Insulin resistance contributed to the development of type 2 diabetes (T2D) and is a major risk factor for diabetic cardiomyopathy (DCM). We have previously reported that insulin resistance led to impaired Akt1 translocation into myocardial mitochondria in DCM. To study the role of mitochondrial Akt1 in DCM, we have generated two cardiac-specific inducible Cre-lox transgenic mice models that expresses (1) a mitochondria-targeting dominant negative Akt (CAMDAKT) or (2) a mitochondria-targeting constitutively active Akt (CAMCAKT) upon Tamoxifen induction (T). T-CAMDAKT mice showed LV dysfunction with increased heart failure markers, while T-CAMCAKT mice restored LV dysfunction to normal in the T2D model. In a T2D model induced by high fat/high fructose diet with relative insulin deficiency, T-CAMCAKT mice showed lower body fat mass (16.6% vs. 26.5%, p<0.001) and higher body lean mass (77.1% vs. 68.1%, p<0.001). To study the mechanism underlying the changes of body composition, we performed transcriptomic profiling and analysis in gonadal white adipose tissues (WAT) by bulk RNA sequencing. When compared to the control T2D mice, 544 genes were upregulated and 1077 genes were downregulated in the WAT of T-CAMCAKT T2D mice. The result indicated enhanced lipid catabolism, triglyceride catabolism, HDL assembly, and downregulated critical nuclear transcription. Pathway analysis revealed the Liver X receptor/Retinoid X receptor signaling was activated in WAT of T-CAMCAKT mice as compared to the controls. This was accompanied by increased fatty acid oxidation and apolipoproteins expression. These findings suggest that impaired mitochondrial Akt signaling in DCM could remotely increase adiposity by reducing lipid catabolism in WAT through modulating LXR/RXR signaling. Disclosure Y. Chen: None. A. Ta: None. E. Tom: None. Y. Chen: None. P.H. Wang: Board Member; Self; Dianavi. Funding National Institutes of Health (R01HL096987)

Resveratrol-Loaded Liposomes: Browning Subcutaneous White Adipose Tissue for Combating Obesity in C57BL/6 J Mice

Abstract Objectives Trans-resveratrol (R) is a potential browning compound and can induce beige adipocyte formation in subcutaneous white adipose tissue (WAT). However, R's low aqueous solubility and high hepatic metabolism limit its application in combating obesity. Hence, we synthesized R-loaded liposomes (Rlipo). The objectives of this study are to measure Rlipo characteristics and determine the browning and anti-obesity efficacy for local delivery of Rlipo to inguinal WAT (I-WAT) in obese mice. Methods The particle size and zeta potential of Rlipo and void liposomes (Vlipo) were measured using a Brookhaven BI-MAS particle size and ZetaPALS analyzer, respectively. Their physical stability was measured daily at 4, 22 and 37°C for 7 days. The in vitro R release pattern of Rlipo was measured using a dialysis method. For determining anti-obesity activities, C57BL/6 J mice were fed the high-fat diet (HFD) for 9 weeks. During week 5–9, mice were treated with saline, free R, Vlipo, or Rlipo via I-WAT injection twice per week. Food intake, body weight, and body composition were measured weekly, and the glucose tolerance test was conducted at week 9. After sacrifice, we collected and measured the mass of liver and fat depots. The mRNA levels of uncoupling protein-1 (UCP-1) and other beige markers in I-WAT were measured using real-time PCR. Results As compared to free R, Rlipo increased R's aqueous solubility by more than 30 times. The particle sizes of Rlipo and Vlipo were about 100 nm. Their zeta potentials were around −25 mV. Both Rlipo and Vlipo have good physical stability at 3 tested temperatures for 7 days and Rlipo exhibited a prolonged-release manner. In the animal study, Rlipo-treated compared to free R-treated mice had 1.2-, 1.4-, 1.6-, 1.5-fold lower body weight, fat %, I-WAT, and gonadal WAT mass, respectively, which were correlated with 1.8- and 2.6-fold higher UCP-1 and TMEM26 mRNA levels in I-WAT. However, no significant differences were found in food intake and the glucose tolerance test. Conclusions Rlipo increased R's aqueous solubility and improved its sustained release manner. Rlipo had higher anti-obesity activities than free R, which were correlated with increased expression of beige markers in I-WAT of mice. Browning subcutaneous WAT using Rlipo might provide an innovative and efficient approach for combating obesity. Funding Sources NIH 1R15AT010395.

Systemic Dermatitis Model Mice Exhibit Atrophy of Visceral Adipose Tissue and Increase Stromal Cells via Skin-Derived Inflammatory Cytokines.

Adipose tissue (AT) is the largest endocrine organ, producing bioactive products called adipocytokines, which regulate several metabolic pathways, especially in inflammatory conditions. On the other hand, there is evidence that chronic inflammatory skin disease is closely associated with vascular sclerotic changes, cardiomegaly, and severe systemic amyloidosis in multiple organs. In psoriasis, a common chronic intractable inflammatory skin disease, several studies have shown that adipokine levels are associated with disease severity. Chronic skin disease is also associated with metabolic syndrome, including abnormal tissue remodeling; however, the mechanism is still unclear. We addressed this problem using keratin 14-specific caspase-1 overexpressing transgenic (KCASP1Tg) mice with severe erosive dermatitis from 8 weeks of age, followed by re-epithelization. The whole body and gonadal white AT (GWAT) weights were decreased. Each adipocyte was large in number, small in size and irregularly shaped; abundant inflammatory cells, including activated CD4+ or CD8+ T cells and toll-like receptor 4/CD11b-positive activated monocytes, infiltrated into the GWAT. We assumed that inflammatory cytokine production in skin lesions was the key factor for this lymphocyte/monocyte activation and AT dysregulation. We tested our hypothesis that the AT in a mouse dermatitis model shows an impaired thermogenesis ability due to systemic inflammation. After exposure to 4 °C, the mRNA expression of the thermogenic gene uncoupling protein 1 in adipocytes was elevated; however, the body temperature of the KCASP1Tg mice decreased rapidly, revealing an impaired thermogenesis ability of the AT due to atrophy. Tumor necrosis factor (TNF)-α, IL-1β and interferon (INF)-γ levels were significantly increased in KCASP1Tg mouse ear skin lesions. To investigate the direct effects of these cytokines, BL/6 wild mice were administered intraperitoneal TNF-α, IL-1β and INF-γ injections, which resulted in small adipocytes with abundant stromal cell infiltration, suggesting those cytokines have a synergistic effect on adipocytes. The systemic dermatitis model mice showed atrophy of AT and increased stromal cells. These findings were reproducible by the intraperitoneal administration of inflammatory cytokines whose production was increased in inflamed skin lesions.

SUN-644 Effects of Steroid Hormones on Lipogenesis and Insulin Sensitivity - an Insight into the Involvement of the Wnt Signaling Pathway

Gestational diabetes mellitus (GDM), a condition in which the state of pregnancy induces the development of diabetes, is characterized by heightened maternal insulin resistance. The levels of sex steroid hormones generally increase during pregnancy. It is thought that imbalance in the levels of steroids like estradiol (E2) and progesterone (P4) with respect to each other, may increase susceptibility towards GDM. To understand the metabolic effects of these steroids, ovariectomized (OVX) rats were treated with E2 or P4 at dosages mimicking the true hormonal status as in pregnancy. E2 significantly reduced the body weight gain (145.4±1.4% to 108.3±0.8%, p<0.001, n≥12) as well as the cumulative food intake (391.3±14.6 g to 312.5±9.0 g, p<0.001) over the course of the 23 day-treatment period. It also decreased the quantity of accumulated gonadal white adipose tissue (GWAT) in the body (3.3±0.2 g to 1.1±0.1 g, p<0.001) and repressed expression of lpl (1.3±0.2 fold, p<0.05) and other lipogenesis markers. P4, on the other hand, enhanced lpl expression (3.7±0.2 fold, p<0.001), but did not affect the total quantity of GWAT. Further, E2 treatment brought about an increase in the expression of insulin sensitivity markers like insr in the GWAT (4.5±0.6 fold, p<0.001) and soleus skeletal muscle (6.2±0.3 fold, p<0.001), as well as an increase in the protein levels of GLUT4.GDM susceptibility in pregnant women is most commonly associated with SNPs in the tcf7l2 gene, the product of which is an effector of the canonical Wnt signaling pathway. It has also been reported that certain actions of steroid hormones are mediated by Wnt signaling. Moreover, we found that tcf7l2 and other components of this pathway (β-catenin protein, lrp5) were up-regulated following treatments with E2 (3.8±0.2 fold, p<0.001 in GWAT; 5.3±0.2 fold, p<0.001 in soleus) and P4 (2.1±0.2 fold, p<0.05 in GWAT; 2.9±0.3 fold, p<0.001 in soleus). We therefore hypothesized that the metabolic actions of these steroids may be mediated by Wnt signaling. To test this hypothesis, we conducted experiments in which OVX rats treated with steroids as described above, were additionally treated with niclosamide (NIC), a Wnt pathway inhibitor. NIC in conjunction with E2 increased GWAT accumulation and lipogenesis, thereby reversing the action of E2. NIC treatment in OVX rats did not change these parameters, indicating that this effect is specific to the inhibition of Wnt signaling modulated by E2. Additionally, NIC inhibited the E2-modulated increase in insulin sensitivity in GWAT and soleus. Taken together, the results suggest that the actions of E2 on insulin sensitivity and lipogenesis are mediated by the Wnt signaling pathway. No such observation was made with respect to the effect of P4 on lipogenesis. Understanding the mechanistic actions of these steroids may play an important role in devising methods to prevent conditions like GDM before its onset.

Adipogenic effects of prenatal exposure to bisphenol S (BPS) in adult F1 male mice

Bisphenol S (BPS) has been increasingly used as a substitute for bisphenol A (BPA), a known endocrine disruptor. Early-life exposure to BPA affects fetal development and the risk of obesity in adolescence and adulthood. However, the effects of fetal exposure BPS in later life are unknown. This study aimed to investigate the effects of prenatal BPS exposure on adiposity in adult F1 mice. Pregnant C57BL/6 N mice were exposed to BPS (0, 0.05, 0.5, 5, and 50 mg/kg/d) via drinking water from gestation day 9 until delivery. Thereafter, two groups of offspring (6 weeks old) were either administered a standard diet (STD) or a high-fat diet (HFD) for 4 weeks until euthanasia. The body weight and gonadal white adipose tissue (gWAT) mass were determined, and the energy expenditure for the adiposity phenotype was computed especially for male mice, followed by histological analysis of the gWAT. Thereafter, the expression levels of adipogenic marker genes (Pparg, Cebpa, Fabp4, Lpl, and Adipoq) were analyzed in the gWAT via reverse-transcription PCR analysis. BPS-exposed male mice displayed apparent gWAT hypertrophy, consistent with the significant increase in adipocyte size in the gWAT and upregulation of Pparg and its direct target genes among HFD mice in comparison with the control mice. These results suggest that prenatal BPS exposure potentially increases the susceptibility to HFD-induced adipogenesis in male adult mice.

Real-ambient exposure to air pollution exaggerates excessive growth of adipose tissue modulated by Nrf2 signal

Air pollution was becoming a global threat to the public health, which was primarily mediated by PM2.5 induced cardiovascular diseases and pulmonary diseases. Recently, observational epidemiologic studies proposed the link between PM2.5 and obesity. Consistently, the link was also supported by limited animal researches. However, the potential mechanism mediating the harmful effects of PM2.5 was still elusive. In this study, we applied the “real-ambient exposure” system to conduct the experiments, which was closer to the status of ambient air pollution compared with the method of intratracheal instillation and concentrated air particles (CAPs) exposure system. Nuclear factor E2-related factor 2 (Nrf2) was previously reported to protect against inflammation and oxidative stress when exposed to PM2.5. Here, we reported that Nrf2−/− mice developed overgrowth of adipose tissue after “real-ambient exposure” to PM2.5, compared to filtered air (FA) group. Consistently, compared to FA group, adipocytes from subcutaneous (sWAT) and gonadal (gWAT) white adipose tissue of Nrf2−/− mice exhibited enlarged cell size in PM2.5 exposure group. Furthermore, the levels of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) in serum and liver of Nrf2−/− mice were also altered statistically in PM2.5 exposure group. Importantly, when the expression of lipogenic enzymes was analyzed, the levels of the related specific genes in adipose tissue and liver of Nrf2−/− mice were altered in PM2.5 exposure group. Interestingly, the key transcription factors modulating expression of lipogenic enzymes in liver of Nrf2−/− mice were also found altered in PM2.5 exposure group, such as peroxisome proliferator-activated receptor (PPARα, PPARγ). Taken together, our study mimicked the status of ambient air pollution, revealed new insights into the adverse effect of PM2.5 exposure, provided new link between air pollution and overgrowth of adipose tissue, and supported the vital role of Nrf2 in mediating the side effects of PM2.5.

Molecular Mechanisms of P311 on White Adipogenesis

BackgroundThe obesity epidemic is a constant and chronic detriment to US as well as global health outcomes. Two‐thirds of the US population is either overweight or obese, and obesity can be linked to many chronic diseases, including diabetes mellitus, cardiovascular diseases, stroke and cancer. Diet and exercise remains the primary therapeutic approaches, but still obesity (40% of US adult population) incidence and prevalence continues to rise, prompting the development of new interventions. P311 is an 8 kDa protein shown to induce adipogenesis in an in vitro 3T3‐L1 cell culture model (Nunez et al. 2019). In the current study, we investigated the molecular mechanisms of P311 in white adipocyte biology.MethodsBoth male and female C57BL/6 control mice and P311 knockout (KO) mice were used for this study. Adipocytes were isolated from individual white adipose tissue depots and adipocyte number and size were quantified using LipidTox staining followed by Guava EasyCyte analysis. Additionally adipocyte cellular functions of P311 like apoptosis, lipophagy and adipose tissue macrophage numbers were verified in P311 KOs and compared with wild type control mice. Real‐time PCR, western blot and immunohistology studies were conducted as described by Badri et al. (2013) and Nunez et al. (2019)ResultsP311 was expressed in murine gonadal and subcutaneous white adipose tissue. White adipocytes isolated from 4‐month‐old mice had significantly higher levels of P311 compared to adipocytes isolated from the white subcutaneous adipose tissue of 1‐month‐old mice. However, progenitor cells (stromal vascular fraction) showed no (basal) expression of P311. P311 KO mice showed decreased PPARγ2 expression. P311 KO mice did not differ from wild type mice in subcutaneous or gonadal white adipose tissue weights, but they had fewer and enlarged adipocytes. Further, P311 KOs also showed decreased apoptosis and lipophagy along with decreased adipocyte macrophage numbers and browning of white adipose tissue. In addition, adult human visceral adipose tissue also showed the expression of P311 in adipocytes implicating a translational role for P311 in adipogenesis and obesity.ConclusionsP311 plays a key role in white adipogenesis and browning of WAT partly through modulating PPARγ2 and also by regulating adipocyte cellular processes including adipocyte apoptosis, lipophagy, browning and macrophage numbers.Support or Funding Information• 2019 Medical Student Summer Research and Public Health Experience (Morehouse School of Medicine)• NIMHD/NIH grant funding through S21MD000101 (to Morehouse School of Medicine)• U54MD008621 (Hampton University, Hampton, VA)

Metabolic Effects of Maternal Bisphenol F Exposure in Population‐based Heterogeneous Stock Rats

Bisphenol F (BPF) is marketed as a ‘safe’ substitute for bisphenol A (BPA), a risk factor for obesity and heart disease, in manufacturing polycarbonates and in common consumer products. BPF’s environmental presence is growing rapidly and is detected in 66.5% of U.S. adults. There is evidence of individual variation in bisphenol levels, suggesting that gene x environment (GxE) interactions influence risk of cardiometabolic disease from bisphenol exposure. Few studies of BPF exposure in either humans or animals have been performed, thus their associated health risks are mostly unknown. Traditional in vivo toxicity studies are performed in genetically undefined outbred rats or genetically homogeneous inbred mice, leading to conflicting results possibly due to GxE interactions. The N/NIH Heterogeneous Stock (HS) rats are outbred rats that better model humans yet are amenable to genetic study. Our overall hypothesis is that BPF exposure is a cardiometabolic disease risk factor based on underlying genetic susceptibility, which can be identified using the HS rat model.We previously demonstrated that five weeks of post‐wean BPF exposure significantly impacts body growth and adiposity in male HS rats. The goal of this project was to determine if maternal BPF exposure also influences growth and adiposity in HS rats, since maternal exposure to BPA is known to impact the metabolic health of both the mother and offspring. HS female breeders were randomly selected for exposure to either vehicle (0.1% Ethanol), 0.1125 mg/L BPF in 0.1% Ethanol (Low Dose), or 1.125 mg/L BPF in 0.1% Ethanol (High Dose) in drinking water during gestation and lactation (~6 weeks total exposure time). One pup of each sex was weaned at 3 weeks of age with no additional exposure. Tissues were taken from dams. Weight and adiposity measures were obtained from weanlings until 8 weeks of age.Our study determined that dams exposed to High Dose showed significantly increased gonadal white adipose tissue (GWAT) mass and trended increased brown adipose tissue (BAT) mass (Table 1). Maternal High Dose exposure impacted weanling body composition at 7 weeks of age as measured by nuclear magnetic resonance (NMR), with the female weanlings significantly increasing %fat mass and trending decreased %lean mass. Maternal BPF exposure also impacted weanling BAT mass, with High Dose female weanlings trending increased BAT mass. No differences were found in male offspring. Our preliminary data suggest that maternal BPF exposure alters adiposity of both the HS dams and female offspring. This work supports BPF exposure as a cardiometabolic disease risk factor and indicates that the HS rat will be a useful model for dissecting GxBPF interactions on metabolic health.Support or Funding InformationNIH P30 ES005605, National Institutes of Health Predoctoral Training Grant T32GM008629 Subject Phenotype Vehicle Low Dose High Dose Dam % BAT (mg) 313 ± 14 343 ± 20 370 ± 31 GWAT (g) 5.7 ± 0.4 5.3 ± 0.5 7.9 ± 0.8 * Female Weanling # Fat % 9.9 ± 1.1 14.0 ± 2.9 17.0 ± 2.0 * Lean % 73.0 ± 1.1 69.3 ± 2.6 66.4 ± 1.7 BAT (mg) 175 ± 9 180 ± 10 213.8 ± 23 Values: mean ± SEM %Vehicle n = 10, Low Dose n = 9, High Dose n = 5 #Vehicle n = 10, Low Dose n = 10, High Dose n = 8 (NMR Vehicle n = 8, Low Dose n = 6, High Dose n = 4) *p &lt; 0.05 High Dose vs Vehicle (linear mixed model regression, Likelihood Ratio Test)

Lactational metformin exposure programs offspring white adipose tissue glucose homeostasis and resilience to metabolic stress in a sex-dependent manner.

We previously demonstrated that exposing mouse dams to metformin during gestation results in increased beta-cell mass at birth and increased beta-cell insulin secretion in adult male offspring. Given these favorable changes after a gestational maternal metformin exposure, we wanted to understand the long-term metabolic impact on offspring after exposing dams to metformin during the postnatal window. The newborn period provides a feasible clinical window for intervention and is important for beta-cell proliferation and metabolic tissue development. Using a C57BL/6 model, we administered metformin to dams from the day of birth to postnatal day 21. We monitored maternal health and offspring growth during the lactation window, as well as adult glucose homeostasis through in vivo testing. At necropsy we assessed pancreas and adipocyte morphology using histological and immunofluorescent staining techniques. We found that metformin exposure programmed male and female offspring to be leaner with a higher proportion of small adipocytes in the gonadal white adipose tissue (GWAT). Male, but not female, offspring had an improvement in glucose tolerance as young adults concordant with a mild increase in insulin secretion in response to glucose in vivo. These data demonstrate long-term metabolic programming of offspring associated with maternal exposure to metformin during lactation.

Low-dose UV radiation before running wheel access activates brown adipose tissue

In previous preclinical studies, low (non-burning) doses of UV radiation (UVR) limited weight gain and metabolic dysfunction in mice fed with a high-fat diet. Here, we explored the effects of low-dose UVR on physical activity and food intake and mechanistic pathways in interscapular brown adipose tissue (iBAT). Young adult C57Bl/6J male mice, housed as individuals, were fed a high-fat diet and exposed to low-dose UVR (sub-oedemal, 1 kJ/m2 UVB, twice-a-week) or 'mock' treatment, with or without running wheel access (2 h, for 'moderate' physical activity) immediately after phototherapy. There was no difference in distance run in mice exposed to UVR or mock-treated over 12 weeks of exposure to running wheels (P = 0.14). UVR (alone) did not significantly affect food intake, adiposity, or signs of glucose dysfunction. Access to running wheels increased food intake (after 10 weeks, P ≤ 0.02) and reduced gonadal white adipose tissue and iBAT mass (P ≤ 0.03). Body weight and hepatic steatosis were lowest in mice exposed to UVR with running wheel access. In the iBAT of mice exposed to UVR and running wheels, elevated Atgl, Cd36, Fasn, Igf1, Pparγ, and Ucp1 mRNAs and reduced CD11c on F4-80 + MHC class II+ macrophages were observed, while renal Sglt2 mRNA levels were increased, compared to high-fat diet alone (P ≤ 0.03). Blood levels of 25-hydroxyvitamin D were not increased by exposure to UVR and/or access to running wheels. In conclusion, when combined with physical activity, low-dose UVR may more effectively limit adiposity (specifically, body weight and hepatic steatosis) and modulate metabolic and immune pathways in iBAT.

Obesity Reduces Maternal Blood Triglyceride Concentrations by Reducing Angiopoietin-Like Protein 4 Expression in Mice

To ensure fetal lipid supply, maternal blood triglyceride (TG) concentrations are robustly elevated during pregnancy. Interestingly, a lower increase in maternal blood TG concentrations has been observed in some obese mothers. We have shown that high-fat (HF) feeding during pregnancy significantly reduces maternal blood TG levels. Therefore, we performed this study to investigate if and how obesity alters maternal blood TG levels. Maternal obesity was established by prepregnant HF (ppHF) feeding, which avoided the dietary effect during pregnancy. We found not only that maternal blood TG concentrations in ppHF dams were remarkably lower than in control dams but also that the TG peak occurred earlier during gestation. Hepatic TG production and intestinal TG absorption were unchanged in ppHF dams, but systemic lipoprotein lipase (LPL) activity was increased, suggesting that increased blood TG clearance contributes to the decreased blood TG concentrations in ppHF dams. Although significantly higher levels of UCP1 protein were observed in interscapular brown adipose tissue (iBAT) of ppHF dams, Ucp1 gene deletion did not restore blood TG concentrations in ppHF dams. Expression of the angiopoietin-like protein 4 (ANGPTL4), a potent endogenous LPL inhibitor, was significantly increased during pregnancy. However, the pregnancy-induced elevation of blood TG was almost abolished in Angptl4 -/- dams. Compared with control dams, Angptl4 mRNA levels were significantly lower in iBAT, gonadal white adipose tissue, and livers of ppHF dams. Importantly, ectopic overexpression of ANGPTL4 restored maternal blood TG concentrations in ppHF dams. Together, these results indicate that ANGPTL4 plays a vital role in increasing maternal blood TG concentrations during pregnancy. Obesity impairs the rise of maternal blood TG concentrations by reducing ANGPTL4 expression in mice.

Regulated in Development and DNA Damage Responses 1 Prevents Dermal Adipocyte Differentiation and Is Required for Hair Cycle–Dependent Dermal Adipose Expansion

Dermal white adipose tissue (dWAT) expansion is associated with important homeostatic and pathologic processes in skin. Even though mTOR/protein kinase B signaling is important for adipogenesis, the role of regulated development of DNA damage responses 1 (REDD1), a negative regulator of mTOR/protein kinase B, is poorly understood. Loss of REDD1 in mice resulted in reduction of body mass, total fat, size of gonadal white adipose tissue, and interscapular brown adipose tissue. Inguinal subcutaneous white adipose tissue and dWAT in REDD1 knockouts were expanded compared with wild type mice. Size and number of mature adipocytes in dWAT were also increased in adult REDD1 knockouts. This dWAT phenotype was established around postnatal day 18 and did not depend on the hair growth cycle. Numbers of adipocyte precursor cells were lower in REDD1 knockout skin. Invitro analysis revealed increased differentiation of skin-derived REDD1 knockout adipocyte precursor cells as indicated by higher lipid accumulation and increased adipogenic marker expression. 3T3L1 cells overexpressing REDD1 had decreased sensitivity to differentiation. Overall, our findings indicate that REDD1 silencing induced expansion of dWAT through hypertrophy and hyperplasia. This REDD1-dependent mechanism of adipogenesis could be used to preferentially target skin-associated adipose tissue for therapeutic purposes.

Antisense oligonucleotide treatment produces a type I interferon response that protects against diet-induced obesity

ObjectiveIn mouse models, deficiency of TTC39B (T39) decreases hepatic lipogenic gene expression and protects against diet-induced steatohepatitis. While assessing the therapeutic potential of antisense oligonucleotides (ASOs) targeting T39, we discovered an unexpected weight loss phenotype. The objective of this study was to determine the mechanism of the resistance to diet-induced obesity. MethodsTo assess therapeutic potential, we used antisense oligonucleotides (ASO) to knock down T39 expression in a Western or high-fat, high-cholesterol, high-sucrose-diet-fed Ldlr−/− or wild-type mice. ResultsT39 ASO treatment led to decreased hepatic lipogenic gene expression and decreased hepatic triglycerides. Unexpectedly, T39 ASO treatment protected against diet-induced obesity. The reduced weight gain was seen with two different ASOs that decreased T39 mRNA in adipose tissue macrophages (ATMs), but not with a liver-targeted GalNac-ASO. Mice treated with the T39 ASO displayed increased browning of gonadal white adipose tissue (gWAT) and evidence of increased lipolysis. However, T39 knockout mice displayed a similar weight loss response when treated with T39 ASO, indicating an off-target effect. RNA-seq analysis of gWAT showed a widespread increase in type I interferon (IFN)-responsive genes, and knockout of the IFN receptor abolished the weight loss phenotype induced by the T39 ASO. Some human T39 ASOs and ASOs with different modifications targeting LDLR also induced a type I IFN response in THP1 macrophages. ConclusionOur data suggest that extrahepatic targeting of T39 by ASOs in ATMs produced an off-target type 1 IFN response, leading to activation of lipolysis, browning of WAT, and weight loss. While our findings suggest that ASOs may induce off-target type 1 IFN response more commonly than previously thought, they also suggest that therapeutic induction of type 1 IFN selectively in ATMs could potentially represent a novel approach to the treatment of obesity.

The association between maternal nicotine exposure and adipose angiogenesis in female rat offspring: A mechanism of adipose tissue function changes

Maternal smoking during pregnancy and lactation is associated with increased fat mass in the offspring, but the mechanism by which this occurs is not fully understood. Our study focused on the relationships among maternal nicotine exposure, adipose angiogenesis and adipose tissue function in female offspring. Pregnant rats were randomly assigned to nicotine or control groups. Microvascular density, lipid metabolism and α7nAChR-Egr1-FGF2 signaling pathway genes/proteins were tested in 4-, 12- and 26-week female offspring. In vitro, nicotine concentration- and time-response experiments were conducted in 3T3-L1. Lipid metabolism and α7nAChR-Egr1-FGF2 signaling pathway genes/proteins were tested. The conditioned media of differentiated 3T3-L1 treated with nicotine were used to observe tube formation in human umbilical vein endothelial cells (HUVECs). Nicotine-exposed females presented higher adipose microvascular density. The gene expression of α7nAChR, Egr1 and FGF2 was significantly increased in gonadal white adipose tissue (gWAT) and inguinal subcutaneous WAT (igSWAT) of nicotine-exposed females at 4 weeks of age. The protein expression of α7nAChR, Egr1 and FGF2 was increased in gWAT and igSWAT of nicotine-exposed females at 4 weeks of age, and increased in gWAT at 26 weeks. In vitro, nicotine increased the expression of lipid metabolism and α7nAChR-Egr1-FGF2 signaling pathway genes/proteins in a concentration- and time-dependent manner. In the tube formation experiment, adipocytes affected by nicotine promoted HUVEC angiogenesis. Therefore, maternal nicotine exposure promoted the early angiogenesis of adipose tissue via the α7nAChR-Egr1-FGF2 signaling pathway, and this angiogenesis mechanism was associated with increased adipogenesis in adipose tissue of female offspring.

Deficiency in AIM2 induces inflammation and adipogenesis in white adipose tissue leading to obesity and insulin resistance

Absent in melanoma 2 (AIM2) is a cytosolic sensor for double-stranded DNA and a tumour suppressor. Binding of double-stranded DNA to AIM2 forms the AIM2 inflammasome, leading to activation of caspase-1 and production of IL-1β and IL-18. Although inflammasome-independent effects of AIM2 have been reported, its role in energy metabolism is unknown. We aimed to evaluate the effect of AIM2 in energy metabolism and glucose homeostasis. Male and female whole body Aim2 knockout (Aim2-/-) mice were used in the current study. Body weight, food intake, body composition, energy expenditure, fasting blood glucose levels, GTT and body temperature were measured at indicated time points. RNA sequencing was carried out on gonadal white adipose tissue (gWAT) in 14-month-old female mice. mRNA and protein levels in tissues were analysed by quantitative real-time PCR and immunoblot. Immune cell infiltration in gWAT was examined by flow cytometry. Stromal vascular fractions isolated from gWAT were used to investigate adipocyte differentiation. Male and female Aim2-/- mice were obese compared with wild-type controls from 7weeks of age until 51weeks of age, with increased adiposity in both subcutaneous and visceral fat depots. While there were no differences in food intake, Aim2-/- mice demonstrated decreased energy expenditure and impaired brown adipose tissue function compared with wild-type controls. Fasting glucose and insulin levels were elevated, and Aim2-/- mice were glucose intolerant on intraperitoneal GTT. RNA sequencing revealed marked upregulation of the IFN-inducible gene Ifi202b, which encodes protein 202 (p202) and elevated inflammatory signalling in gWAT of Aim2-/- mice. Increased infiltration of total and Ly6Clow monocytes was noted at 8weeks of age in gWAT, before the onset of obesity and insulin resistance. Ifi202b knockdown blocked adipogenesis in stromal vascular fractions and reduced inflammation in bone marrow-derived macrophages, demonstrating a key role of p202 in mediating the increased adipogenesis and inflammation in Aim2-/- mice. These results demonstrate a fundamental role for AIM2 in energy metabolism, inflammation and insulin resistance. Our studies establish a novel link between the innate immunity proteins, AIM2 and p202, and metabolism.

Differential Sympathetic Activation of Adipose Tissues by Brain-Derived Neurotrophic Factor.

Centrally administered brain-derived neurotrophic factor (BDNF) decreases body adiposity beyond what can be accounted for by decreased food intake, implying enhanced lipid metabolism by BDNF. Consistent with this notion, intracerebroventricular (icv) injection of BDNF in rats increased the expression of lipolytic enzymes in white adipose tissues (WAT) and increased circulating concentrations of lipolytic products without changing the levels of adrenal gland hormones. This suggests that central BDNF-induced lipid mobilization is likely due to sympathetic neural activation, rather than activation of the adrenocortical or adrenomedullary system. We hypothesized that BDNF activated sympathetic innervation of adipose tissues to regulate lipolysis. Rats with unilateral denervation of interscapular brown adipose tissue (BAT) and different WAT depots received icv injections of saline or BDNF. Both intact and denervated adipose tissues were exposed to the same circulating factors, but denervated adipose tissues did not receive neural signals. Norepinephrine (NE) turnover (NETO) of BAT and WAT was assessed as a measure of sympathetic activity. Findings revealed that central BDNF treatment induced a change in NETO in some but not all the adipose tissues tested. Specifically, greater NETO rates were found in BAT and gonadal epididymal WAT (EWAT), but not in inguinal WAT (IWAT) or retroperitoneal WAT (RWAT), of BDNF-treated rats compared to saline-treated rats. Furthermore, intact innervation was necessary for BDNF-induced NETO in BAT and EWAT. In addition, BDNF increased the expression of lipolytic enzymes in both intact and denervated EWAT and IWAT, suggesting that BDNF-induced WAT lipolysis was independent of intact innervation. To summarize, centrally administered BDNF selectively provoked sympathetic drives to BAT and EWAT that was dependent on intact innervation, while BDNF also increased lipolysis in a manner independent of intact innervation.

MicroRNA-10a-5p regulates macrophage polarization and promotes therapeutic adipose tissue remodeling

ObjectiveThis study investigated the role of microRNAs generated from adipose tissue macrophages (ATMs) during adipose tissue remodeling induced by pharmacological and nutritional stimuli. MethodsMacrophage-specific Dicer knockout (KO) mice were used to determine the roles of microRNA generated in macrophages in adipose tissue remodeling induced by the β3-adrenergic receptor agonist CL316,243 (CL). RNA-seq was performed to characterize microRNA and mRNA expression profiles in isolated macrophages and PDGFRα+ adipocyte stem cells (ASCs). The role of miR-10a-5p was further investigated in cell culture, and in adipose tissue remodeling induced by CL treatment and high fat feeding. ResultsMacrophage-specific deletion of Dicer elevated pro-inflammatory gene expression and prevented CL-induced de novo beige adipogenesis in gonadal white adipose tissue (gWAT). Co-culture of ASCs with ATMs of wild type mice promoted brown adipocyte gene expression upon differentiation, but co-culture with ATMs of Dicer KO mice did not. Bioinformatic analysis of RNA expression profiles identified miR-10a-5p as a potential regulator of inflammation and differentiation in ATMs and ASCs, respectively. CL treatment increased levels of miR-10a-5p in ATMs and ASCs in gWAT. Interestingly, CL treatment elevated levels of pre-mir-10a in ATMs but not in ASCs, suggesting possible transfer from ATMs to ASCs. Elevating miR-10a-5p levels inhibited proinflammatory gene expression in cultured RAW 264.7 macrophages and promoted the differentiation of C3H10T1/2 cells into brown adipocytes. Furthermore, treatment with a miR-10a-5p mimic in vivo rescued CL-induced beige adipogenesis in Dicer KO mice. High fat feeding reduced miR-10a-5p levels in ATMs of gWAT, and treatment of mice with a miR-10a-5p mimic suppressed pro-inflammatory responses, promoted the appearance of new white adipocytes in gWAT, and improved systemic glucose tolerance. ConclusionsThese results demonstrate an important role of macrophage-generated microRNAs in adipogenic niches and identify miR-10a-5p as a key regulator that reduces adipose tissue inflammation and promotes therapeutic adipogenesis.

Adipocyte-specific disruption of ATPase copper transporting α in mice accelerates lipoatrophy.

ATPase copper transporting α (ATP7A), also known as Menkes disease protein, is a P-type ATPase that transports copper across cell membranes. The critical role of ATP7A-mediated copper homeostasis has been well recognised in various organs, such as the intestine, macrophages and the nervous system. However, the importance of adipocyte ATP7A-mediated copper homeostasis on fat metabolism is not well understood. Here, we sought to reveal the contribution of adipose ATP7A to whole-body fat metabolism in mice. We generated adipocyte-specific Atp7a-knockout (ASKO) mice using the Cre/loxP system, with Cre expression driven by the adiponectin promoter. ASKO mice and littermate control mice were aged on a chow diet or fed with a high-fat diet (HFD); body weight, fat mass, and glucose and insulin metabolism were analysed. Histological analysis, transmission electron microscopy and RNA-sequencing (RNA-Seq) analysis of white adipose tissue (WAT) were used to understand the physiological and molecular changes associated with loss of copper homeostasis in adipocytes. Significantly increased copper concentrations were observed in adipose tissues of ASKO mice compared with control mice. Aged or HFD-fed ASKO mice manifested a lipoatrophic phenotype characterised by a progressive generalised loss of WAT. Dysfunction of adipose tissues in these ASKO mice was confirmed by decreased levels of both serum leptin and adiponectin and increased levels of triacylglycerol and insulin. Systemic metabolism was also impaired in these mice, as evidenced by a pronounced glucose intolerance, insulin resistance and hepatic steatosis. Moreover, we demonstrate a significant induction of lipolysis and DNA-damage signalling pathways in gonadal WAT from aged and HFD-fed ASKO mice. In vitro studies suggest that copper overload is responsible for increased lipolysis and DNA damage. Our results show a previously unappreciated role of adipocyte Atp7a in the regulation of ageing-related metabolic disease and identify new metallophysiologies in whole-body fat metabolism. The datasets generated during the current study are available in the Genome Sequence Archive in BIG Data Center, Beijing Institute of Genomics (BIG), Chinese Academy of Sciences, under accession number CRA001769 (http://bigd.big.ac.cn/gsa).

Life-span Extension Drug Interventions Affect Adipose Tissue Inflammation in Aging.

The National Institute on Aging (NIA)-sponsored Interventions Testing Program (ITP) has identified a number of dietary drug interventions that significantly extend life span, including rapamycin, acarbose, and 17-α estradiol. However, these drugs have diverse downstream targets, and their effects on age-associated organ-specific changes are unclear (Nadon NL, Strong R, Miller RA, Harrison DE. NIA Interventions Testing Program: investigating putative aging intervention agents in a genetically heterogeneous mouse model. EBioMedicine. 2017;21:3-4. doi:10.1016/j.ebiom.2016.11.038). Potential mechanisms by which these drugs extend life could be through their effect on inflammatory processes often noted in tissues of aging mice and humans. Our study focuses on the effects of three drugs in the ITP on inflammation in gonadal white adipose tissue (gWAT) of HET3 mice-including adiposity, adipose tissue macrophage (ATM) M1/M2 polarization, markers of cellular senescence, and endoplasmic reticulum stress. We found that rapamycin led to a 56% increase of CD45+ leukocytes in gWAT, where the majority of these are ATMs. Interestingly, rapamycin led to a 217% and 106% increase of M1 (CD45+CD64+CD206-) ATMs in females and males, respectively. Our data suggest rapamycin may achieve life-span extension in part through adipose tissue inflammation. Additionally, HET3 mice exhibit a spectrum of age-associated changes in the gWAT, but acarbose and 17-α estradiol do not strongly alter these phenotypes-suggesting that acarbose and 17- α estradiol may not influence life span through mechanisms involving adipose tissue inflammation.

Lack of monoacylglycerol lipase prevents hepatic steatosis by favoring lipid storage in adipose tissue and intestinal malabsorption

Monoacylglycerol lipase (MGL) is the rate-limiting enzyme in the degradation of monoacylglycerols. To examine the role of MGL in hepatic steatosis, WT and MGL KO (MGL-/-) mice were challenged with a Western diet (WD) over 12 weeks. Lipid metabolism, inflammation, and fibrosis were assessed by serum biochemistry, histology, and gene-expression profiling of liver and adipose depots. Intestinal fat absorption was measured by gas chromatography. Primary adipocyte and 3T3-L1 cells were analyzed by flow cytometry and Western blot. Human hepatocytes were treated with MGL inhibitor JZL184. The absence of MGL protected mice from hepatic steatosis by repressing key lipogenic enzymes in liver (Srebp1c, Pparγ2, and diacylglycerol O-acyltransferase 1), while promoting FA oxidation. Liver inflammation was diminished in MGL-/- mice fed a WD, as evidenced by diminished epidermal growth factor-like module-containing mucin-like hormone receptor-like 1 (F4/80) staining and C-C motif chemokine ligand 2 gene expression, whereas fibrosis remained unchanged. Absence of MGL promoted fat storage in gonadal white adipose tissue (gWAT) with increased lipogenesis and unchanged lipolysis, diminished inflammation in gWAT, and subcutaneous AT. Intestinal fat malabsorption prevented ectopic lipid accumulation in livers of MGL-/- mice fed a WD. In vitro experiments demonstrated increased adipocyte size/lipid content driven by PPARγ. In conclusion, our data uncover that MGL deletion improves some aspects of nonalcoholic fatty liver disease by promoting lipid storage in gWAT and fat malabsorption.