Adipocyte Triglyceride Lipase Research Articles

TRPV3 facilitates lipolysis and attenuates diet-induced obesity via activation of the NRF2/FSP1 signaling axis

Transient receptor potential vanilloid (TRPV) ion channels play a crucial role in various cellular functions by regulating intracellular Ca2+ levels and have been extensively studied in the context of several metabolic diseases. However, the regulatory effects of TRPV3 in obesity and lipolysis are not well understood. In this study, utilizing a TRPV3 gain-of-function mouse model (TRPV3G568V/G568V), we assessed the metabolic phenotype of both TRPV3G568V/G568V mice and their control littermates, which were randomly assigned to either a 12-week high-fat diet or a control diet. We investigated the potential mechanisms underlying the role of TRPV3 in restraining obesity and promoting lipolysis both in vivo and in vitro. Our findings indicate that a high-fat diet led to significant obesity, characterized by increased epididymal and inguinal white adipose tissue weight and higher fat mass. However, the gain-of-function mutation in TRPV3 appeared to counteract these adverse effects by enhancing lipolysis in visceral fat through the upregulation of the major lipolytic enzyme, adipocyte triglyceride lipase (ATGL). In vitro experiments using carvacrol, a TRPV3 agonist, demonstrated the promotion of lipolysis and antioxidation in 3T3-L1 adipocytes after TRPV3 activation. Notably, carvacrol failed to stimulate Ca2+ influx, lipolysis, and antioxidation in 3T3-L1 adipocytes treated with BAPTA-AM, a cell-permeable calcium chelator. Our results revealed that TRPV3 activation induced the action of transcriptional factor nuclear factor erythroid 2-related factor 2 (NRF2), resulting in increased expression of ferroptosis suppressor protein 1 (FSP1) and superoxide dismutase2 (SOD2). Moreover, the inhibition of NRF2 impeded carvacrol-induced lipolysis and antioxidation in 3T3-L1 adipocytes, with downregulation of ATGL, FSP1, and SOD2. In summary, our study suggests that TRPV3 promotes visceral fat lipolysis and inhibits diet-induced obesity through the activation of the NRF2/FSP1 signaling axis. We propose that TRPV3 may be a potential therapeutic target in the treatment of obesity.

Network Meta-Analysis: Effect of Cold Stress on the Gene Expression of Swine Adipocytes ATGL, CIDEA, UCP2, and UCP3.

Cold stress significantly affects gene expression in adipocytes; studying this phenomenon can help reveal the pathogeneses of conditions such as obesity and insulin resistance. Adipocyte triglyceride lipase (ATGL); cell death-inducing deoxyribonucleic acid (DNA) fragmentation factor subunit alpha (DFFA)-like effector (CIDEA); and uncoupling protein genes UCP1, UCP2, and UCP3 are the most studied genes in pig adipose tissues under cold stress. However, contradictory results have been observed in gene expression changes to UCP3 and UCP2 when adipose tissues under cold stress were examined. Therefore, we conducted a meta-analysis of 32 publications in total on the effect of cold stress on the expression of ATGL, CIDEA, UCP2, and UCP3. Our results showed that cold stress affected the expression of swine adipocyte genes; specifically, it was positively correlated with the expression of UCP3 in swine adipocytes. Conversely, expression of ATGL was negatively affected under cold stress conditions. In addition, the loss of functional UCP1 in pigs likely triggered a compensatory increase in UCP3 activity. We also simulated the docking results of UCP2 and UCP3. Our results showed that UCP2 could strongly bind to adenosine triphosphate (ATP), meaning that UCP3 played a more significant role in pig adipocytes.

IL-4 activates the futile triacylglyceride cycle for glucose utilization in white adipocytes.

The development of cardiometabolic complications during obesity is strongly associated with chronic latent inflammation in hypertrophied adipose tissue (AT). IL-4 is an anti-inflammatory cytokine, playing a protective role against insulin resistance, glucose intolerance and weight gain. The positive effects of IL-4 are associated not only with the activation of anti-inflammatory immune cells in AT, but also with the modulation of adipocyte metabolism. IL-4 is known to activate lipolysis and glucose uptake in adipocytes, but the precise regulatory mechanisms and physiological significance of these processes remain unclear. In this study, we detail IL-4 effects on glucose and triacylglycerides (TAGs) metabolism and propose mechanisms of IL-4 metabolic action in adipocytes. We have shown that IL-4 activates glucose oxidation, lipid droplet (LD) fragmentation, lipolysis and thermogenesis in mature 3T3-L1 adipocytes. We found that lipolysis was not accompanied by fatty acids (FAs) release from adipocytes, suggesting FA re-esterification. Moreover, glucose oxidation and thermogenesis stimulation depended on adipocyte triglyceride lipase (ATGL) activity, but not the uncoupling protein (UCP1) expression. Based on these data, IL-4 may activate the futile TAG-FA cycle in adipocytes, which enhances the oxidative activity of cells and heat production. Thus, the positive effect of IL-4 on systemic metabolism can be the result of the activation of non-canonical thermogenic mechanism in AT, increasing TAG turnover and utilization of excessive glucose.

Vitisin A-13-O-β-D-glucoside and Vitisin A from Iris lactea inhibit lipogenesis and promote lipolysis via the PKA/HSL pathway during adipogenic transdifferentiation of C2C12 cells

Oligostilbenes are a group of natural products derived from the polymerization of stilbene monomers. Despite the demonstration of their activities in regulating lipid metabolism, the function of oligostilbenes in the adipogenic transdifferentiation of multipotent myoblast cells remains unknown. Hence, the five oligostilbenes from Iris lactea were tested for their regulatory effects on adipogenic transdifferentiation of C2C12 myoblast cells. As a result, it was shown that Vitisin A-13-O-β-D-glucoside (VitAOG), Vitisin A (VitA) and Hopeaphenol (Hop) can greatly inhibit the adipogenic transdifferentiation of C2C12 cells by reducing lipid accumulation and downregulating the expression of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding protein beta (C/EBPβ) and fatty acid binding proteins 4 (FABP4). In contrast, Vitisin D (VitD) and Isohopeaphenol (Isohop) promote adipogenic transdifferentiation of C2C12 cells by increasing lipid accumulation and upregulating the expression of adipogenesis and lipogenesis markers. Further research found that the lipolytic protein levels of adipocyte triglyceride lipase (ATGL) and phosphorylation of hormone-sensitive lipase (HSL) were elevated by VitAOG and VitA. Additionally, VitAOG and VitA maintain lipid homeostasis by improving mitochondrial function. Taken together, our study reveals an effect of oligostilbenes on lipid metabolism in C2C12 cells, and VitAOG and VitA can be regarded as potential candidates for the treatment of obesity and other disorders of lipid metabolism.

Naringin reduces fat deposition by promoting the expression of lipolysis and β-oxidation related genes

AimsNaringin, a flavonoid present in citrus fruits, has been known for the capacity to reduce lipid synthesis and anti-inflammatory. In this study, we investigated whether naringin increases lipolysis and fatty acid β-oxidation to change fat deposition. MethodsIn in vivo experiment, obese adult mice (20-weeks-old, n = 18) were divided into control group fed with normal diet and naringin-treated group fed with naringin-supplemented diet (5 g/kg) for 60 days, respectively. In in vitro experiment, differentiated 3T3-L1 adipocytes were treated for four days with or without naringin (100 µg/mL). ResultsSupplementing naringin significantly reduced the body weight, abdominal fat weight, blood total cholesterol content of mice, but did not affect food intake. In addition, naringin decreased levels of pro-inflammatory factors in adipose tissue including interleukin-1β (IL-1β), interleukin-6 (IL-6), and monocyte chemotactic protein 1 (MCP-1). Naringin increased the expression of AMP-activated protein kinase (AMPK), a key factor in cellular energy metabolism, and raised the ratio of p-AMPK/AMPK in mouse liver tissue. The protein expression of hormone-sensitive lipase (HSL), phospho-HSL563 (p-HSL563), p-HSL563/HSL, and adipocyte triglyceride lipase (ATGL) was significantly increased in the adipose tissue of naringin-treated mice. Furthermore, naringin enhanced the expression of fatty acid β-oxidation genes, including carnitine palmitoyl transferase 1 (CPT1), uncoupling protein 2 (UCP2), and acyl-coenzyme A oxidase 1 (AOX1) in mouse adipose tissue. In in vitro experiment, similar findings were observed in differentiated 3T3-L1 adipocytes with naringin treatment. The treatment remarkably reduced intracellular lipid content, increased the number of mitochondria and promoted the gene expression of HSL, ATGL, CPT1, AOX1, and UCP2 and the phosphorylation of HSL protein. ConclusionNaringin reduced body fat in obese mice and lipid content in differentiated 3T3-L1 adipocytes, which was associated with enhanced AMPK activation and upregulation of the expression of the lipolytic genes HSL, ATGL, and β-oxidation genes CPT1, AOX1, and UCP2.

Cardiomyocyte p38 MAPKα suppresses a heart–adipose tissue–neutrophil crosstalk in heart failure development

Although p38 MAP Kinase α (p38 MAPKα) is generally accepted to play a central role in the cardiac stress response, to date its function in maladaptive cardiac hypertrophy is still not unambiguously defined. To induce a pathological type of cardiac hypertrophy we infused angiotensin II (AngII) for 2 days via osmotic mini pumps in control and tamoxifen-inducible, cardiomyocyte (CM)-specific p38 MAPKα KO mice (iCMp38αKO) and assessed cardiac function by echocardiography, complemented by transcriptomic, histological, and immune cell analysis. AngII treatment after inactivation of p38 MAPKα in CM results in left ventricular (LV) dilatation within 48 h (EDV: BL: 83.8 ± 22.5 µl, 48 h AngII: 109.7 ± 14.6 µl) and an ectopic lipid deposition in cardiomyocytes, reflecting a metabolic dysfunction in pressure overload (PO). This was accompanied by a concerted downregulation of transcripts for oxidative phosphorylation, TCA cycle, and fatty acid metabolism. Cardiac inflammation involving neutrophils, macrophages, B- and T-cells was significantly enhanced. Inhibition of adipose tissue lipolysis by the small molecule inhibitor of adipocytetriglyceride lipase (ATGL) Atglistatin reduced cardiac lipid accumulation by 70% and neutrophil infiltration by 30% and went along with an improved cardiac function. Direct targeting of neutrophils by means of anti Ly6G-antibody administration in vivo led to a reduced LV dilation in iCMp38αKO mice and an improved systolic function (EF: 39.27 ± 14%). Thus, adipose tissue lipolysis and CM lipid accumulation augmented cardiac inflammation in iCMp38αKO mice. Neutrophils, in particular, triggered the rapid left ventricular dilatation. We provide the first evidence that p38 MAPKα acts as an essential switch in cardiac adaptation to PO by mitigating metabolic dysfunction and inflammation. Moreover, we identified a heart–adipose tissue–immune cell crosstalk, which might serve as new therapeutic target in cardiac pathologies.

Effect of Long-Term Continuous Light Exposure and Western Diet on Adropin Expression, Lipid Metabolism, and Energy Homeostasis in Rats.

Long-term continuous light exposure (CL) and western diet (WD) effects on Adropin expression, RORα, and Rev-erb-α nuclear receptors and energy homeostasis were studied in rats. Thirty-two male Wistar rats (250-290 g) were enrolled for 3 months in the following groups (n = 8/group): (a) Normal control group (NC), (b) CL group, (c) WD group, and (d) CL + WD group. Then, indirect calorimetry and food intake (FI) were measured. Finally, Adropin, hormone-sensitive lipase (HSL), adipocyte triglyceride lipase (ATGL), and free fatty acids (FFA) were measured. Additionally, the histopathology and gene expression of Enho, RORα, and Rev-erb-α genes were done. The CL alone elevated the Adropin plasma level and gene expression, increased RORα expression, and decreased the Rev-erb-α nuclear receptor expression mainly in the liver and kidney. Besides, CL increased the total energy expenditure (TEE) and decreased the respiratory quotient. WD alone or in combination with the CL reversed gene expression of Enho, RORα, and Rev-erb-α. Combined CL and WD increased the TEE, reduced the food intake, increased the ATGL, and reduced the Adropin level in addition to widespread degenerative changes in the liver, spleen, and renal tissues. The deleterious effects of CL and WD on energy homeostasis may include Adropin with the involvement of the RORα and Rev-erb-α nuclear receptors.

Fatty Acid Metabolism during Exercise

Obesity-induced metabolic syndrome is becoming a severe health problem in Japan due to the increasing popularity of the Western-style diet and fast food. Endurance exercise is one of the most effective ways to reduce fat content and thus prevent metabolic syndrome, as endurance exercise leads to larger amounts of fatty acids being used to create energy with higher efficiency in skeletal muscle. There are two major types of skeletal muscle fibers: type I muscle fibers, which contain a large number of mitochondria and burn fatty acids for energy, and type II fibers, which contain fewer mitochondria and depend on glycolysis to acquire energy. Endurance exercise results in the development of type I muscle fibers and enhanced mitochondrial function, with increased expression and activity of mitochondrial enzymes such as carnitine palmitoyltransferase 1, β-hydroxy-acyl-CoA dehydrogenase and citrate synthase. On the other hand, in adipose tissues, higher amounts of fatty acids are released to support their increased usage in muscle fibers by increasing the activity levels of adipocyte triglyceride lipase and hormone-sensitive lipase following endurance exercise. The increased usage of fatty acids is considered an outcome of activated peroxidase proliferator-activated receptors (PPARs), nuclear receptors for fatty acids, and the induced transcription of proteins that play essential roles in fatty acid metabolism upon stimulation of those fatty acids. In three PPAR isoforms, muscle fibers predominantly express PPARγ, a regulator of mitochondrial enzyme transcription and type I muscle fiber development. In adipocytes, PPARγ is abundantly expressed to regulate fatty acid catabolism. Furthermore, skeletal muscles, adipose tissues and other tissues communicate through hormones such as myokines and adipokines, which optimize fatty acid metabolism in the entire body during endurance exercise. Collectively, endurance exercise shifts our energy metabolism to be more lipolytic for a healthier lifestyle.

Decoration of myocellular lipid droplets with perilipins as a marker for in vivo lipid droplet dynamics: A super-resolution microscopy study in trained athletes and insulin resistant individuals

In many different cell types neutral lipids can be stored in lipid droplets (LDs). Nowadays, LDs are viewed as dynamic organelles, which store and release fatty acids depending on energy demand (LD dynamics). Proteins like perilipin 2 (PLIN2) and PLIN5 decorate the LD membrane and are determinants of LD lipolysis and fat oxidation, thus affecting LD dynamics. Trained athletes and type 2 diabetes (T2D) patients both have high levels of intramyocellular lipid (IMCL). While IMCL content scales negatively with insulin resistance, athletes are highly insulin sensitive in contrast to T2D patients, the so-called athlete's paradox. Differences in LD dynamics may be an underlying factor explaining the athlete's paradox. We aimed to quantify PLIN2 and PLIN5 content at individual LDs as a reflection of the ability to switch between fatty acid release and storage depending on energy demand. Thus, we developed a novel fluorescent super-resolution microscopy approach and found that PLIN2 protein abundance at the LD surface was higher in T2D patients than in athletes. Localization of adipocyte triglyceride lipase (ATGL) to the LD surface was lower in LDs abundantly decorated with PLIN2. While PLIN5 abundance at the LD surface was similar in athletes and T2D patients, we have observed previously that the number of PLIN5 decorated LDs was higher in athletes, indicating more LDs in close association with mitochondria. Thus, in athletes interaction of LDs with mitochondria was more pronounced and LDs have the protein machinery to be more dynamic, while in T2D patients the LD pool is more inert. This observation contributes to our understanding of the athlete's paradox.

Abstract 648: Role of G0S2 in chronic myeloid leukemia and TKI resistance

Abstract Tyrosine kinase inhibitors (TKIs) targeting BCR-ABL1 have turned chronic myeloid leukemia (CML) from a fatal to a chronic disease. However, resistance is a clinical problem, and TKIs do not target CML leukemic stem cells (LSC), which are independent from BCR-ABL1 kinase activity. To understand mechanisms driving BCR-ABL1-independent resistance, we analyzed the transcriptional signature of TKI-naïve CD34+ cells from patients with or without a response to imatinib after 12 months of therapy (McWeeney et al. Blood 2010). Among the genes most profoundly downregulated in patients destined to fail imatinib was G0/G1 switch gene 2 (G0S2) (>3-fold, n=59, p<0.02). Retrospective analysis of survival data for patients whose samples were evaluated in a microarray revealed that high G0S2 expression (>50%) correlated with a longer overall survival (n=30 responders, n=16 non-responders, p=0.036). We next analyzed G0S2 mRNA expression in CD34+ cells from normal cord blood and from primary CD34+ cells lacking BCR-ABL1 kinase domain mutations. G0S2 was 4-fold downregulated in newly diagnosed CML (n=6) compared to normal cord blood (n=5, p<0.01), and further downregulated by >3-fold in TKI-resistant (n=2) and BP-CML samples (n=5, p<0.01).G0S2 mRNA was also lower in CD34+38- stem cells compared to committed CD34+38+ progenitor cells in CML (n=6, p<0.01) but not normal cord blood (n=4, p=ns). CFSE staining revealed that G0S2 mRNA levels in CP-CML CD34+ cells are lowest in cell populations with the least number of cell divisions. To assess the role of G0S2 in CML, we cloned G0S2 amplified from normal human mononuclear cells into a lentiviral expression system, and confirmed ectopic expression by qRT-PCR and immunoblot. Ectopic G0S2 reduced colony formation in both TKI-sensitive and TKI-resistant CML cell lines and CD34+ CML patient samples. While G0S2 has been reported to induce apoptosis by direct inhibition of BCL-2, reduced colony formation was not associated with an increase of apoptosis, but did restore imatinib-induced apoptosis. These data are consistent with a tumor suppressor role for G0S2 in CML. G0S2 has also been shown to inhibit adipocyte triglyceride lipase (ATGL), the rate-limiting enzyme in the conversion of triglycerides to free fatty acids (FFAs). While ATGL is indeed expressed at the protein level in CML cells, shRNAs targeting ATGL do not phenocopy ectopic G0S2 expression. Furthermore, the effects of ectopic G0S2 are not impaired in cells with simultaneous ATGL knockdown, and ectopic G0S2 has no effect on intracellular FFA or ATP levels. Finally, G0S2 gene expression has been shown to be regulated by promoter DNA hypermethylation. However, DNA bisulfite and patch PCR sequencing in primary CD34+ cells from CML patients did not reveal G0S2 promoter hypermethylation in CML. Rather, ChIP-PCR revealed the presence of MYC/MAX at the G0S2 promoter in CML, suggesting MYC-mediated transcriptional repression. Altogether, these data suggest that G0S2 downregulation plays a functional role in CML disease progression and TKI response, but is independent from its role as an inhibitor of BCL-2 or ATGL. These data unravel a new role for G0S2 as a regulator of TKI response in CML, and suggest that restoring G0S2 expression may have clinical utility. Citation Format: Mayra A. Gonzalez, Alfonso E. Bencomo, Christian Barreto-Vargas, Andres J. Rubio, Idaly M. Olivas, Joshua J. Lara, Anna Senina, Jonathan Ahmann, Katherine T. Varley, Luis F. Jave-Suarez, O'Hare Thomas, Michael W. Deininger, Anna M. Eiring. Role of G0S2 in chronic myeloid leukemia and TKI resistance [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 648.

Mortality From Coronavirus Disease 2019 Increases With Unsaturated Fat and May Be Reduced by Early Calcium and Albumin Supplementation

Mortality From Coronavirus Disease 2019 Increases With Unsaturated Fat and May Be Reduced by Early Calcium and Albumin Supplementation

Adipocyte lipolysis: from molecular mechanisms of regulation to disease and therapeutics.

Fatty acids (FAs) are stored safely in the form of triacylglycerol (TAG) in lipid droplet (LD) organelles by professional storage cells called adipocytes. These lipids are mobilized during adipocyte lipolysis, the fundamental process of hydrolyzing TAG to FAs for internal or systemic energy use. Our understanding of adipocyte lipolysis has greatly increased over the past 50 years from a basic enzymatic process to a dynamic regulatory one, involving the assembly and disassembly of protein complexes on the surface of LDs. These dynamic interactions are regulated by hormonal signals such as catecholamines and insulin which have opposing effects on lipolysis. Upon stimulation, patatin-like phospholipase domain containing 2 (PNPLA2)/adipocyte triglyceride lipase (ATGL), the rate limiting enzyme for TAG hydrolysis, is activated by the interaction with its co-activator, alpha/beta hydrolase domain-containing protein 5 (ABHD5), which is normally bound to perilipin 1 (PLIN1). Recently identified negative regulators of lipolysis include G0/G1 switch gene 2 (G0S2) and PNPLA3 which interact with PNPLA2 and ABHD5, respectively. This review focuses on the dynamic protein-protein interactions involved in lipolysis and discusses some of the emerging concepts in the control of lipolysis that include allosteric regulation and protein turnover. Furthermore, recent research demonstrates that many of the proteins involved in adipocyte lipolysis are multifunctional enzymes and that lipolysis can mediate homeostatic metabolic signals at both the cellular and whole-body level to promote inter-organ communication. Finally, adipocyte lipolysis is involved in various diseases such as cancer, type 2 diabetes and fatty liver disease, and targeting adipocyte lipolysis is of therapeutic interest.

Metabolic Effects of Testosterone Hormone Therapy in Normal and Orchiectomized Male Rats: From Indirect Calorimetry to Lipolytic Enzymes.

Background and Aim Changes in total energy expenditure (TEE) and substrate metabolism may help explain the metabolic actions of testosterone (T). This study measured respiratory quotient (RQ), TEE, ghrelin, insulin, and key lipolysis enzyme concentrations in relation to body weight (wt) and food intake (FI) in both normal and bilaterally orchiectomized rats with/without T treatment. Methods In total, thirty-two male Wistar rats (300–400 g) were divided into four groups (n = 8/group), including (a) sham-operated and vehicle-injected group (Sham), (b) T-treated sham group (T-Sham) for which sham-operated rats were injected with IM testosterone undecanoate (100 mg/kg, for one week), (c) orchiectomy and vehicle-injected group (Orch), and (d) T-replaced orchiectomy group (T-Orch). After one week, FI and wt were automatically recorded, indirect calorimetry parameters were measured, and blood samples were collected to measure T, ghrelin, insulin, growth hormone (GH), glucose, hormone-sensitive lipase (HSL), adipocyte triglyceride lipase (ATGL), free fatty acids (FFA), and lipid profiles. Results Orchiectomy decreased ghrelin, GH, and insulin levels, increased TEE and RQ, and lowered FI and wt. The T-Orch group exhibited increased levels of ghrelin (3-fold), insulin, GH, blood levels of lipolysis products, TEE, and FI in addition to reduced glucose levels (P < 0.05). This group demonstrated no significant changes in wt. In the T-Sham group, T increased ghrelin and insulin levels (P < 0.05) with strong positive correlations (r = 0.663 and 0.644, respectively, P < 0.05), increased ATGL levels, RQ toward carbohydrate utilization ranges, and TEE, and reduced HSL levels (P < 0.05) with insignificant changes in FI or wt. Conclusions T administration in orchiectomized rats significantly increased orexigenic mediators such as ghrelin and insulin without inducing any significant changes in wt. The mechanism for this finding might be the increased TEE and the stimulation of lipolysis through the ATGL enzyme. The associated rise of GH might help in interference with accumulation of lipid in adipose tissue. Apart from the effect on GH, T-Sham showed similar effects of T supplementation.

Lipolytic Effects of Testosterone Hormone Replacement Therapy in A Rat Model of Andropause Versus Normal Controls

AbstractBackground: Testosterone (T) actions extend beyond the reproductive functions to include diverse metabolic pathways. Lipolytic effect of T is still underinvestigated, especially regarding the involved enzymes.Aim of Study: This work measures two key lipolysis-enzymes in both normal and orchiectomized rats with/without T administration.Material and Methods: Forty rats (200-300g) were sub-divided into 4 equal groups (n=10/group); (A) Group I: Sham-operated control group. (B) Group II: Sham-operated rats were injected with IM testosterone undecanoate (100mg/kg, for two weeks). (C) Group III: Andropause model was done by orchiectomy, (D) Group IV: Testosterone-replacement therapy in orchiectomized rats. T, Hormone-Sensitive Lipase (HSL), Adipocyte Triglyceride Lipase (ATGL), Free Fatty Acids (FFA), and lipid profile were measured using the commercially available ELISA kits. Food intake was measured manually in addition to body weight changes before during and after treatment. ANOVA with LSD post hoc test and Pearson correlation were used for analysis.Results: The castrated rats showed lower food intake, lower body weight, and lower weight gain. Regarding adipose tissue lipolytic enzymes, ATGL was significantly decreased while both HSL and FFA were insignificantly changed. T replacement therapy in castrated rats increased blood products of lipolysis due to an increased level of ATGL, HSL, and FFA, in addition to the significant increase in food intake without significant wt changes. Similar effects were demon-strated in normal rats treated with T.Conclusion: T hormone therapy increased food intake, without significant changes in weight due to stimulation of lipolysis process mainly via stimulation of ATGL and HSL.

Sphk2−/− mice are protected from obesity and insulin resistance

Sphingosine kinases phosphorylate sphingosine to sphingosine 1‑phosphate (S1P), which functions as a signaling molecule. We have previously shown that sphingosine kinase 2 (Sphk2) is important for insulin secretion. To obtain a better understanding of the role of Sphk2 in glucose and lipid metabolism, we have characterized 20- and 52-week old Sphk2−/− mice using glucose and insulin tolerance tests and by analyzing metabolic gene expression in adipose tissue. A detailed metabolic characterization of these mice revealed that aging Sphk2−/− mice are protected from metabolic decline and obesity compared to WT mice. Specifically, we found that 52-week old male Sphk2−/− mice had decreased weight and fat mass, and increased glucose tolerance and insulin sensitivity compared to control mice. Indirect calorimetry studies demonstrated an increased energy expenditure and food intake in 52-week old male Sphk2−/− versus control mice. Furthermore, expression of adiponectin gene in adipose tissue was increased and the plasma levels of adiponectin elevated in aged Sphk2−/− mice compared to WT. Analysis of lipid metabolic gene expression in adipose tissue showed increased expression of the Atgl gene, which was associated with increased Atgl protein levels. Atgl encodes for the adipocyte triglyceride lipase, which catalyzes the rate-limiting step of lipolysis. In summary, these data suggest that mice lacking the Sphk2 gene are protected from obesity and insulin resistance during aging. The beneficial metabolic effects observed in aged Sphk2−/− mice may be in part due to enhanced lipolysis by Atgl and increased levels of adiponectin, which has lipid- and glucose-lowering effects.

The GTPase ARFRP1 affects lipid droplet protein composition and triglyceride release from intracellular storage of intestinal Caco-2 cells

Intestinal release of dietary triglycerides via chylomicrons is the major contributor to elevated postprandial triglyceride levels. Dietary lipids can be transiently stored in cytosolic lipid droplets (LDs) located in intestinal enterocytes for later release. ADP ribosylation factor-related protein 1 (ARFRP1) participates in processes of LD growth in adipocytes and in lipidation of lipoproteins in liver and intestine. This study aims to explore the impact of ARFRP1 on LD organization and its interplay with chylomicron-mediated triglyceride release in intestinal-like Caco-2 cells. Suppression of Arfrp1 reduced release of intracellularly derived triglycerides (0.69-fold) and increased the abundance of transitional endoplasmic reticulum ATPase TERA/VCP, fatty acid synthase-associated factor 2 (FAF2) and perilipin 2 (Plin2) at the LD surface. Furthermore, TERA/VCP and FAF2 co-occurred more frequently with ATGL at LDs, suggesting a reduced adipocyte triglyceride lipase (ATGL)-mediated lipolysis. Accordingly, inhibition of lipolysis reduced lipid release from intracellular storage pools by the same magnitude as Arfrp1 depletion. Thus, the lack of Arfrp1 increases the abundance of lipolysis-modulating enzymes TERA/VCP, FAF2 and Plin2 at LDs, which might decrease lipolysis and reduce availability of fatty acids for triglyceride synthesis and their release via chylomicrons.

FAM134B promotes adipogenesis by increasing vesicular activity in porcine and 3T3-L1 adipocytes.

Family with sequence similarity 134, Member B (FAM134B), is a cis-Golgi transmembrane protein that is known to be necessary for the long-term survival of nociceptive and autonomic ganglion neurons. Recent work has shown that FAM134B plays a pivotal role in autophagy-mediated turnover of endoplasmic reticulum (ER) membranes, tumor inhibition and lipid homeostasis. In this study, we provide mechanistic links between FAM134B and ARF-related protein 1 (ARFRP1) and further show that FAM134B resides in the Golgi apparatus. Here, we found that FAM134B increased lipid accumulation in adipocytes. Transport vehicle number and ADP-ribosylation factor (ARF) family gene expression were also increased by FAM134B overexpression, suggesting that vesicular transport activity enhanced lipid accumulation. ARF-related protein 1 (ARFRP1) is a GTPase that promotes protein trafficking. We show that FAM134B regulates the expression of ARFRP1, and the knockdown of ARFRP1 abolishes enhancement on lipid accumulation caused by FAM134B. In addition, FAM134B upregulates the PAT family protein (PAT), which associates with the lipid droplets (LDs) surface and promotes lipolysis by recruiting adipocyte triglyceride lipase (ATGL). These findings indicate that FAM134B promotes lipid accumulation and adipogenic differentiation by increasing vesicle transport activity in the Golgi apparatus and inhibiting the lipolysis of LDs.

Ilex paraguariensis modulates fat metabolism in Caenorhabditis elegans through purinergic system (ADOR-1) and nuclear hormone receptor (NHR-49) pathways.

Ilex paraguariensis is a well-known plant that is widely consumed in South America, primarily as a drink called mate. Mate is described to have stimulant and medicinal properties. Considering the potential anti-lipid effects of I. paraguariensis infusion, we used an extract of this plant as a possible modulator of fat storage to control lipid metabolism in worms. Herein, the I. paraguariensis-dependent modulation of fat metabolism in Caenorhabditis elegans was investigated. C. elegans were treated with I. paraguariensis aqueous extract (1 mg/ml) from L1 larvae stage until adulthood, to simulate the primary form of consumption. Expression of adipocyte triglyceride lipase 1 (ATGL-1) and heat shock protein 16.2, lipid accumulation through C1-BODIPY-C12 (BODIPY) lipid staining, behavioral parameters, body length, total body energy expenditure and overall survival were analyzed. Total body energy expenditure was determined by the oxygen consumption rate in N2, nuclear hormone receptor knockout, nhr-49(nr2041), and adenosine receptor knockout, ador-1(ox489) strains. Ilex paraguariensis extract increased ATGL-1 expression 20.06% and decreased intestinal BODIPY fat staining 63.36%, compared with the respective control group, without affecting bacterial growth and energetic balance, while nhr-49(nr2041) and ador-1(ox489) strains blocked the worm fat loss. In addition, I. paraguariensis increased the oxygen consumption in N2 worms, but not in mutant strains, increased N2 worm survival following juglone exposure, and did not alter hsp-16.2 expression. We demonstrate for the first time that I. paraguariensis can decrease fat storage and increase body energy expenditure in worms. These effects depend on the purinergic system (ADOR-1) and NHR-49 pathways. Ilex paraguariensis upregulated the expression of ATGL-1 to modulate fat metabolism. Furthermore, our data corroborates with other studies that demonstrate that C. elegans is a useful tool for studies of fat metabolism and energy consumption.

Coordination Among Lipid Droplets, Peroxisomes, and Mitochondria Regulates Energy Expenditure Through the CIDE-ATGL-PPARα Pathway in Adipocytes.

Metabolic homeostasis is maintained by an interplay among tissues, organs, intracellular organelles, and molecules. Cidea and Cidec are lipid droplet (LD)-associated proteins that promote lipid storage in brown adipose tissue (BAT) and white adipose tissue (WAT). Using ob/ob/Cidea-/- , ob/ob/Cidec-/- , and ob/ob/Cidea-/-/Cidec-/- mouse models and CIDE-deficient cells, we studied metabolic regulation during severe obesity to identify ways to maintain metabolic homeostasis and promote antiobesity effects. The phenotype of ob/ob/Cidea-/- mice was similar to that of ob/ob mice in terms of serum parameters, adipose tissues, lipid storage, and gene expression. Typical lipodystrophy accompanied by insulin resistance occurred in ob/ob/Cidec-/- mice, with ectopic storage of lipids in the BAT and liver. Interestingly, double deficiency of Cidea and Cidec activated both WAT and BAT to consume more energy and to increase insulin sensitivity compared with their behavior in the other three mouse models. Increased lipolysis, which occurred on the LD surfaces and released fatty acids, led to activated β-oxidation and oxidative phosphorylation in peroxisomes and mitochondria in CIDE-deficient adipocytes. The coordination among LDs, peroxisomes, and mitochondria was regulated by adipocyte triglyceride lipase (ATGL)-peroxisome proliferator-activated receptor α (PPARα). Double deficiency of Cidea and Cidec activated energy consumption in both WAT and BAT, which provided new insights into therapeutic approaches for obesity and diabetes.

Lower Stearoyl-CoA Desaturase and Hormone Sensitive Lipase Gene Expression in Superficial Subcutaneous Adipose Tissue of Male, but Not Female, Patients with Type 2 Diabetes

Mitochondrial gene expression in visceral (VAT) and lipogenesis in abdominal subcutaneous adipose tissue (SAT) are lower in insulin resistance (IR). Humans with hormone sensitive lipase (HSL) gene mutations are prone to type 2 diabetes (T2D). SAT is divided into deep (DSAT) and superficial SAT (SSAT). SSAT was speculated to be protective in T2D, but gender specificity is unknown. We hypothesized lower mitochondrial efficiency as well as lower markers of lipogenesis and lipolysis in SSAT only in male T2D patients vs. glucose-tolerant humans (CON), which may characterize dysfunctional SSAT. In 20 T2D and 20 CON matched for sex, BMI and age (female/male: 6/14 per group; 32±1 vs. 31±1 kg/m2, 52±2 vs. 54±2 years), we assessed M-values by euglycemic-hyperinsulinemic clamps, liver fat content (HCL) and VAT by MRS. In biopsies of SSAT, mitochondrial oxidative capacity was measured by respirometry, lipogenesis assessed from stearoyl-CoA desaturase (SCD) mRNA, lipolysis from adipocyte triglyceride lipase (ATGL) and HSL mRNA by RTqPCR. The insulin resistant T2D had 63% and 22% higher HCL (p&amp;lt;0.01) and VAT (p&amp;lt;0.05) than CON. In SSAT, T2D featured 20%, 50%, 70%, 49% reductions in oxidative capacity, SCD, ATGL and HSL mRNA (all p&amp;lt;0.05). Gender segregated analyzes showed higher oxidative capacity only in females, whereas only ATGL was also lower in female T2D vs. CON. In T2D, VAT was 22% lower (p&amp;lt;0.01) and HSL mRNA 70% higher (both p&amp;lt;0.001) in female than in male participants. In conclusion, lower lipogenesis and lipolysis in SSAT of male T2D patients may lead to inadequate lipid storage in SSAT, thereby promoting ectopic fat storage as HCL and VAT. Disclosure K. Bódis: None. J. Lundbom: None. T. Jelenik: None. D.F. Markgraf: None. A. Strom: None. O.P. Zaharia: None. Y. Karusheva: None. V. Burkart: None. K. Müssig: None. Y. Kupriyanova: None. M. Ouni: None. J. Hwang: None. D. Ziegler: None. A. Schuermann: None. M. Roden: Speaker's Bureau; Self; Boehringer Ingelheim GmbH. Research Support; Self; Boehringer Ingelheim GmbH. Consultant; Self; Poxel SA. Research Support; Self; Danone Nutricia Early Life Nutrition, GlaxoSmithKline plc., Nutricia Advanced Medical Nutrition, Sanofi. J. Szendroedi: None.