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Project description:White adipose tissue (WAT) is a highly active metabolic and endocrine organ, and its dysfunction links obesity to a variety of diseases, ranging from type 2 diabetes to cancer. The function of WAT is under the control of multiple cell signaling systems, including that of G protein-coupled receptors (GPCRs). Gαs- and Gαi-coupled receptors have been reported to regulate lipolysis, and Gαq-coupled receptors stimulate glucose uptake in adipocytes. However, the roles of Gα12/13-coupled receptors in WAT are totally unknown. Here we show that lysophosphatidic acid receptor 4 (LPA4), an adipose cluster GPCR, selectively activates Gα12/13 proteins in adipocytes, and limits continuous remodeling and healthy expansion of WAT in mice. Under standard diet conditions, LPA4-knockout mice showed higher expression levels of mitochondrial biogenesis-related genes in WAT, along with higher production of adiponectin than control mice. In vitro studies have consistently demonstrated that the LPA4/Rho/Rho-kinase signaling pathway suppresses mRNA expression of mitochondrial biogenesis-related genes in adipocytes. In a diet-induced obesity model, LPA4-deficient mice showed “metabolically healthy obese” phenotypes, with continuous WAT expansion, and protection from WAT inflammation, hepatosteatosis, and insulin resistance. Given that GPCRs comprise the most successful class of drug targets, LPA4 would be a promising therapeutic target for obesity-related metabolic disorders.
2018-12-23 | GSE66131 | GEO
Project description:White adipose tissue (WAT) is a highly active metabolic and endocrine organ, and its dysfunction links obesity to a variety of diseases, ranging from type 2 diabetes to cancer. The function of WAT is under the control of multiple cell signaling systems, including that of G protein-coupled receptors (GPCRs). Gαs- and Gαi-coupled receptors have been reported to regulate lipolysis, and Gαq-coupled receptors stimulate glucose uptake in adipocytes. However, the roles of Gα12/13-coupled receptors in WAT are totally unknown. Here we show that lysophosphatidic acid receptor 4 (LPA4), an adipose cluster GPCR, selectively activates Gα12/13 proteins in adipocytes, and limits continuous remodeling and healthy expansion of WAT in mice. Under standard diet conditions, LPA4-knockout mice showed higher expression levels of mitochondrial biogenesis-related genes in WAT, along with higher production of adiponectin than control mice. In vitro studies have consistently demonstrated that the LPA4/Rho/Rho-kinase signaling pathway suppresses mRNA expression of mitochondrial biogenesis-related genes in adipocytes. In a diet-induced obesity model, LPA4-deficient mice showed “metabolically healthy obese” phenotypes, with continuous WAT expansion, and protection from WAT inflammation, hepatosteatosis, and insulin resistance. Given that GPCRs comprise the most successful class of drug targets, LPA4 would be a promising therapeutic target for obesity-related metabolic disorders.
2018-12-23 | GSE66130 | GEO
Project description:Gene expression profiles in white adipose tissues of lysophosphatidic acid receptor 4-KO mice
| PRJNA275933 | ENA
Project description:BackgroundLysophosphatidic acid (LPA) receptor signaling has been implicated in cardiovascular and obesity-related metabolic disease. However, the distribution and regulation of LPA receptors in the myocardium and adipose tissue remain unclear.ObjectivesThis study aimed to characterize the mRNA expression of LPA receptors (LPA1-6) in the murine and human myocardium and adipose tissue, and its regulation in response to obesity.MethodsLPA receptor mRNA levels were determined by qPCR in i) heart ventricles, isolated cardiomyocytes, and perigonadal adipose tissue from chow or high fat-high sucrose (HFHS)-fed male C57BL/6 mice, ii) 3T3-L1 adipocytes and HL-1 cardiomyocytes under conditions mimicking gluco/lipotoxicity, and iii) human atrial and subcutaneous adipose tissue from non-obese, pre-obese, and obese cardiac surgery patients.ResultsLPA1-6 were expressed in myocardium and white adipose tissue from mice and humans, except for LPA3, which was undetectable in murine adipocytes and human adipose tissue. Obesity was associated with increased LPA4, LPA5 and/or LPA6 levels in mice ventricles and cardiomyocytes, HL-1 cells exposed to high palmitate, and human atrial tissue. LPA4 and LPA5 mRNA levels in human atrial tissue correlated with measures of obesity. LPA5 mRNA levels were increased in HFHS-fed mice and insulin resistant adipocytes, yet were reduced in adipose tissue from obese patients. LPA4, LPA5, and LPA6 mRNA levels in human adipose tissue were negatively associated with measures of obesity and cardiac surgery outcomes. This study suggests that obesity leads to marked changes in LPA receptor expression in the murine and human heart and white adipose tissue that may alter LPA receptor signaling during obesity.
| S-EPMC5728537 | biostudies-literature
Project description:Mutations in BSCL2 underlie human congenital generalized lipodystrophy type 2 disease. We previously reported that Bscl2 (-/-) mice develop lipodystrophy of white adipose tissue (WAT) due to unbridled lipolysis. The residual epididymal WAT (EWAT) displays a browning phenotype with much smaller lipid droplets (LD) and higher expression of brown adipose tissue marker proteins. Here we used targeted lipidomics and gene expression profiling to analyze lipid profiles as well as genes involved in lipid metabolism in WAT of wild-type and Bscl2(-/-) mice. Analysis of total saponified fatty acids revealed that the residual EWAT of Bscl2(-/-) mice contained a much higher proportion of oleic 18:1n9 acid concomitant with a lower proportion of palmitic 16:0 acid, as well as increased n3- polyunsaturated fatty acids (PUFA) remodeling. The acyl chains in major species of triacylglyceride (TG) and diacylglyceride (DG) in the residual EWAT of Bscl2(-/-) mice were also enriched with dietary fatty acids. These changes could be reflected by upregulation of several fatty acid elongases and desaturases. Meanwhile, Bscl2(-/-) adipocytes from EWAT had increased gene expression in lipid uptake and TG synthesis but not de novo lipogenesis. Both mitochondria and peroxisomal β-oxidation genes were also markedly increased in Bscl2(-/-) adipocytes, highlighting that these machineries were accelerated to shunt the lipolysis liberated fatty acids through uncoupling to dissipate energy. The residual subcutaneous white adipose tissue (ScWAT) was not browning but displays similar changes in lipid metabolism. Overall, our data emphasize that, other than being essential for adipocyte differentiation, Bscl2 is also important in fatty acid remodeling and energy homeostasis.
| S-EPMC3865019 | biostudies-literature
Project description:Lysophosphatidic acid (LPA), a bioactive lysophospholipid, is involved in the pathogenesis of chronic inflammatory and autoimmune diseases. In this study, we investigated the role of LPA/LPA receptor (LPAR) signaling in the pathogenesis of Sjögren's syndrome (SS). We found that autotaxin, an LPA producing enzyme, and LPAR1 and LPAR3 mRNA, and IL-17 mRNA were highly expressed in the exocrine glands of 20-week-old nonobese diabetic (NOD) mice, which show SS symptoms at this age, as compared with non-symptomatic 8-week-old NOD mice. In an adoptive transfer model using NOD lymphocytes, treatment with Ki16425, an LPAR1/3 antagonist, restored tear and saliva secretion and decreased symptoms of SS compared with the vehicle-treated group. IL-17 levels in serum and lacrimal glands were also significantly reduced by Ki16425 in recipient mice. In addition, Ki16425 treatment of 20-week-old NOD mice, which spontaneously developed SS, restored saliva volume. Treatment of NOD splenocytes with LPA induced the expression of IL-17 in a dose-dependent manner, and Ki16425 inhibited this increase. LPA stimulated the activation of ROCK2 and p38 MAPK; and inhibition of ROCK2 or p38 MAPK suppressed LPA-induced IL-17 expression. Our data suggest that LPAR signaling stimulates SS development by induction of IL-17 production via ROCK and p38 MAPK pathways. Thus, LPAR inhibition could be a possible therapeutic strategy for SS.
| S-EPMC5432331 | biostudies-literature
Project description:Given that increased thermogenesis in white adipose tissue, also known as browning, promotes energy expenditure, significant efforts have been invested to determine the molecular factors involved in this process. Here we show that HOXC10, a homeobox domain-containing transcription factor expressed in subcutaneous white adipose tissue, is a suppressor of genes involved in browning white adipose tissue. Ectopic expression of HOXC10 in adipocytes suppresses brown fat genes, whereas the depletion of HOXC10 in adipocytes and myoblasts increases the expression of brown fat genes. The protein level of HOXC10 inversely correlates with brown fat genes in subcutaneous white adipose tissue of cold-exposed mice. Expression of HOXC10 in mice suppresses cold-induced browning in subcutaneous white adipose tissue and abolishes the beneficial effect of cold exposure on glucose clearance. HOXC10 exerts its effect, at least in part, by suppressing PRDM16 expression. The results support that HOXC10 is a key negative regulator of the process of browning in white adipose tissue.
| S-EPMC5336557 | biostudies-literature
Project description:Brown adipose tissue is a thermogenic organ that dissipates stored energy as heat to maintain body temperature. This process may also provide protection from development of diet-induced obesity. We report that the bioactive lipid mediator lysophosphatidic acid (LPA) markedly decreases differentiation of cultured primary brown adipocyte precursors, whereas potent selective inhibitors of the LPA-generating enzyme autotaxin (ATX) promote differentiation. Transgenic mice overexpressing ATX exhibit reduced expression of brown adipose tissue-related genes in peripheral white adipose tissue and accumulate significantly more fat than wild-type controls when fed a high-fat diet. Our results indicate that ATX and its product LPA are physiologically relevant negative regulators of brown fat adipogenesis and are consistent with a model in which a decrease in mature peripheral brown adipose tissue results in increased susceptibility to diet-induced obesity in mice.
| S-EPMC3355557 | biostudies-literature
Project description:Cyclic phosphatidic acid (cPA) is a naturally occurring phospholipid mediator that, along with its chemically stabilized analogue 2-carba-cyclic phosphatidic acid (2ccPA), induces various biological activities in vitro and in vivo. Although cPA is similar to lysophosphatidic acid (LPA) in structure and synthetic pathway, some of cPA biological functions apparently differ from those reported for LPA. We previously investigated the pharmacokinetic profile of 2ccPA, which was found to be rapidly degraded, especially in acidic conditions, yielding an unidentified compound. Thus, not only cPA but also its degradation compound may contribute to the biological activity of cPA, at least for 2ccPA. In this study, we determined the structure and examined the biological activities of 2-carba-lysophosphatidic acid (2carbaLPA) as a 2ccPA degradation compound, which is a type of β-LPA analogue. Similar to LPA and cPA, 2carbaLPA induced the phosphorylation of the extracellular signal-regulated kinase and showed potent agonism for all known LPA receptors (LPA1-6) in the transforming growth factor-α (TGFα) shedding assay, in particular for LPA3 and LPA4. 2carbaLPA inhibited the lysophospholipase D activity of autotaxin (ATX) in vitro similar to other cPA analogues, such as 2ccPA, 3-carba-cPA, and 3-carba-LPA (α-LPA analogue). Our study shows that 2carbaLPA is a novel β-LPA analogue with high potential for the activation of some LPA receptors and ATX inhibition.
| S-EPMC8405639 | biostudies-literature
Project description:The protein arginine methyltransferase 5 (PRMT5) is an emerging regulator of cancer and stem cells including adipogenic progenitors. Here, a new physiological role of PRMT5 in adipocytes and systemic metabolism is reported. Conditional knockout mice were generated to ablate the Prmt5 gene specifically in adipocytes (Prmt5AKO). The Prmt5AKO mice exhibit sex- and depot-dependent progressive lipodystrophy that is more pronounced in females and in visceral (than subcutaneous) white fat. The lipodystrophy and associated energy imbalance, hyperlipidemia, hepatic steatosis, glucose intolerance, and insulin resistance are exacerbated by high-fat-diet. Mechanistically, Prmt5 methylates and releases the transcription elongation factor SPT5 from Berardinelli-Seip congenital lipodystrophy 2 (Bscl2, encoding Seipin) promoter, and Prmt5AKO disrupts Seipin-mediated lipid droplet biogenesis. Prmt5 also methylates Sterol Regulatory Element-Binding Transcription Factor 1a (SREBP1a) and promotes lipogenic gene expression, and Prmt5AKO suppresses SREBP1a-dependent fatty acid metabolic pathways in adipocytes. Thus, PRMT5 plays a critical role in regulating lipid metabolism and lipid droplet biogenesis in adipocytes.
| S-EPMC7709973 | biostudies-literature