Lipid Accumulation In Tissues Research Articles

Rebalancing glucolipid metabolism and gut microbiome dysbiosis by nitrate-dependent alleviation of high-fat diet-induced obesity

IntroductionHigh-fat diet (HFD)-induced obesity is accompanied by compromised nitric oxide (NO) signaling and gut microbiome dysregulation. Inorganic dietary nitrate, which acts as a NO donor, exerts beneficial effects on metabolic...

Effects of High and Low Molecular Weight Chitosan on Plasma Cholesterol, Glucose and Adipocytokines in Diabetic Rats Induced by Streptozotocin and Nicotinamide

Chitosan is known for its lipid-lowering effect. To investigate the comparative effects of low (LCS) and high molecular weight chitosan (HCS) on plasma glucose, cholesterol and adipocytokines, male Sprague-Dawley rats were divided into four groups: normal control, diabetic, and diabetic fed the HCS or LCS diet for seven weeks. Diabetes was induced by subcutaneous injection of nicotinamide and streptozotocin. Results showed that diabetic rats fed the HCS diet had reduced liver weight and perirenal adipose weight, compared to those that were fed the control diet. Higher fecal triglyceride and cholesterol excretion and lower hepatic cholesterol and triglyceride contents were found in diabetic rats fed with both chitosan diets. These observations were more significant in the HCS group than in the LCS group. HCS, but not LCS diet, significantly reduced plasma fructosamine, leptin, total cholesterol and lowered the insulin resistance index (homeostasis model assessment; HOMA) in diabetic rats. A lower intestinal dissaccharidase activity including sucrase and lactase was found in diabetic rats fed the HCS dict. Moreover, plasma tumor necrosis factor-alpha and plasminogen activator inhibitor-1 concentrations were significantly reduced by both chitosan supplementations. The results suggested that HCS feeding may reduce insulin resistance by the suppression of lipid accumulation in liver and adipose tissue and amelioration of chronic inflammation in diabetic rats. HCS may improve glucose and lipid metabolism more significantly than LCS in diabetic rats.

Si-Miao-Yong-An (SMYA) Decoction May Protect the Renal Function Through Regulating the Autophagy-Mediated Degradation of Ubiquitinated Protein in an Atherosclerosis Model.

Hyperlipidemia is common, and its renal toxicity has attracted a great deal of attention. Si-miao-yong-an (SMYA) is a famous ancient decoction of traditional Chinese medicine (TCM), which is still widely used in clinical treatment. In this study, we observed and explored its efficacy and mechanism in protecting renal function in an atherosclerosis model. The results showed that the serum, Cr urinal KIM-1, and NGAL were significantly decreased in SMYA group. Although SMYA failed to alleviate the lipid accumulation, decrease p-NFκB, or increase SOD in kidney tissue, the levels of ubiquitinated protein and P62 were decreased in SMYA group. What is more, a higher LC3 II level was observed in the SMYA group. In conclusion, these data indicated that SMYA decoction may protect renal function in hyperlipidemia via regulating the autophagy-mediated degradation of ubiquitinated protein.

Downregulation of key genes involved in carbon metabolism in Medicago truncatula results in increased lipid accumulation in vegetative tissue

AbstractAlfalfa (Medicago sativa L.) is the most widely grown perennial forage crop and is a close relative of the model diploid legume Medicago truncatula Gaertn. However, use of alfalfa leads to substantial greenhouse gas emissions and economic losses related to inefficiencies in rumen fermentation. The provision of supplemental lipids has been used as a strategy to mitigate these issues, but it is a costly approach. The ability to enhance lipid content within the vegetative tissues of alfalfa would therefore be very advantageous. As such, our aim was to assess and select gene candidates to increase total shoot lipid content in M. truncatula using a virus‐induced gene silencing (VIGS) approach. We targeted gene homologs of the SUGAR‐DEPENDANT 1 (SDP1), ADP‐GLUCOSE‐PYROPHOSPHORYLASE SMALL SUBUNIT 1 (APS1), TRIGALACTOSYLDIACYLGLYCEROL 5 (TGD5), and PEROXISOMAL ABC TRANSPORTER 1 (PXA1) in M. truncatula for silencing. Reduced target transcript levels were confirmed and changes of shoot lipid content and fatty acid composition were measured. Silencing of SDP1, APS1, and PXA1 each resulted in significant increases in shoot total lipid content. Significantly increased proportions of α‐linolenic acid (18:3Δ9cis,12cis,15cis) were observed, and stearic acid (18:0) levels significantly decreased in the total acyl lipids extracted from vegetative tissues of each of the M. truncatula silenced plants. In contrast, palmitic acid (16:0) levels were significantly decreased in only SDP1‐ and PXA1‐silenced plants. Genes of PXA1 and SDP1 would be ideal targets for mutation as a means of improving the quality of alfalfa to increase feed efficiency and minimize greenhouse gas emissions from livestock production in the future.

Moderate quantity of lard mixed with sunflower oil attenuate lipid accumulation in mice

Lard, a fat rich in saturated fatty acids (SFAs), is regarded as a risk factor for metabolic diseases. In the present study, effect of different lard blended with sunflower oil diets on lipid accumulation in adipose tissue, liver, and serum by mouse model was researched. Body weight, body fat percentage, cross-sectional area of adipocytes, liver triglycerides (TGs), and oil red stained area in mice liver of lard blend sunflower oil (L-SFO) group were significantly lower than those of sunflower oil (SFO) group, whereas no significant differences were observed between mice of lard and L-SFO groups. Serum TG and free fatty acid levels were significantly lower in L-SFO group than in other two groups. Furthermore, data showed that sunflower oil decreased contents of hormone-sensitive lipase and carnitine palmitoyl transferase 1 (CPT-1) and increased fatty acid synthase activity in liver tissue. A mixture of lard and sunflower oil rather than only sunflower oil or lard might promote body fat loss and reduce lipid accumulation in adipose tissue, serum, and liver by promoting hydrolysis of TG, increasing β-oxidation of fatty acids. These data suggested that mixing lard and vegetable oil (e.g. sunflower oil) for cooking, or alternate using lard and vegetable oil could be beneficial for reducing body fat.

Serotonin Regulates De Novo Lipogenesis in Adipose Tissues through Serotonin Receptor 2A.

BackgroundObesity is defined as excessive fat mass and is a major cause of many chronic diseases such as diabetes, cardiovascular disease, and cancer. Increasing energy expenditure and regulating adipose tissue metabolism are important targets for the treatment of obesity. Serotonin (5-hydroxytryptophan [5-HT]) is a monoamine metabolite of the essential amino acid tryptophan. Here, we demonstrated that 5-HT in mature adipocytes regulated energy expenditure and lipid metabolism.MethodsTryptophan hydroxylase 1 (TPH1) is the rate-limiting enzyme during 5-HT synthesis in non-neural peripheral tissues. We generated adipose tissue-specific Tph1 knockout (Tph1 FKO) mice and adipose tissue-specific serotonin receptor 2A KO (Htr2a FKO) mice and analyzed their phenotypes during high-fat diet (HFD) induced obesity.ResultsTph1 FKO mice fed HFD exhibited reduced lipid accumulation, increased thermogenesis, and resistance to obesity. In addition, Htr2a FKO mice fed HFD showed reduced lipid accumulation in white adipose tissue and resistance to obesity.ConclusionThese data suggest that the inhibition of serotonin signaling might be an effective strategy in obesity.

Ubiquitination of PPAR-gamma by pVHL inhibits ACLY expression and lipid metabolism, is implicated in tumor progression

BackgroundIntracellular lipid accumulation is associated with various diseases, particularly cancer. Mitochondrial dysfunction is considered as a cause of lipid accumulation; however, the related underlying mechanism remains unclear. FindingsWe found that Von Hippel-Lindau (VHL)-deficiency led to lipid accumulation and mitochondrial dysfunction in renal cell carcinoma cells. Moreover, VHL downregulated ATP-citrate lyase (ACLY), a key enzyme in de novo lipid synthesis, at the transcriptional level, which inhibited intracellular lipid accumulation in human renal carcinoma tissues. We identified PPARγ as the transcription factor regulating ACLY expression by binding to the cis-regulatory site PPRE on its promoter. VHL directly interacted with and promoted ubiquitination of PPARγ, leading to its degradation both in vitro and in vivo, resulting in the downregulation of ACLY. Furthermore, adenovirus-mediated VHL overexpression substantially ameliorated hepatic steatosis induced by a high-fat diet in db/db mice. Importantly, low VHL expression was associated with high ACLY expression and poor prognosis in human liver carcinoma in a dataset in The Cancer Genome Atlas. ConclusionsVHL plays role in cellular lipid metabolism via regulating mitochondria and targeting PPARγ, a transcription factor for ACLY independent of hypoxia-inducible factor 1α. A novel VHL-PPARγ-ACLY axis and its implication in fatty liver disease and cancer were uncovered.

Lemon Balm Extract ALS-L1023 Regulates Obesity and Improves Insulin Sensitivity via Activation of Hepatic PPARα in High-Fat Diet-Fed Obese C57BL/6J Mice.

Our previous studies demonstrated that peroxisome proliferator-activated receptor α (PPARα) activation reduces weight gain and improves insulin sensitivity in obese mice. Since excess lipid accumulation in non-adipose tissues is suggested to be responsible for the development of insulin resistance, this study was undertaken to examine whether the lemon balm extract ALS-L1023 regulates hepatic lipid accumulation, obesity, and insulin resistance and to determine whether its mechanism of action involves PPARα. Administration of ALS-L1023 to high-fat-diet-induced obese mice caused reductions in body weight gain, visceral fat mass, and visceral adipocyte size without changes of food consumption profiles. ALS-L1023 improved hyperglycemia, hyperinsulinemia, glucose and insulin tolerance, and normalized insulin-positive β-cell area in obese mice. ALS-L1023 decreased hepatic lipid accumulation and concomitantly increased the expression of PPARα target genes responsible for fatty acid β-oxidation in livers. In accordance with the in vivo data, ALS-L1023 reduced lipid accumulation and stimulated PPARα reporter gene expression in HepG2 cells. These effects of ALS-L1023 were comparable to those of the PPARα ligand fenofibrate, while the PPARα antagonist GW6471 inhibited the actions of ALS-L1023 on lipid accumulation and PPARα luciferase activity in HepG2 cells. Higher phosphorylated protein kinase B (pAkt)/Akt ratios and lower expression of gluconeogenesis genes were observed in the livers of ALS-L1023-treated mice. These results indicate that ALS-L1023 may inhibit obesity and improve insulin sensitivity in part through inhibition of hepatic lipid accumulation via hepatic PPARα activation.

A Cecropia peltata ethanolic extract reduces insulin resistance and hepatic steatosis in rats fed a high-fat diet

Ethnopharmacological relevanceCecropia peltata L. (CP) leaves have been used in Latin American traditional medicine by its purported hypoglycemic, anti-inflammatory and antioxidant properties. PurposeThe aim of this study was to evaluate the metabolic effects of an ethanolic extract of CP leaves in rats fed a high-fat diet and 10% of sugar in water (HFD). MethodsMale Wistar rats were randomly divided into four groups: group 1 was fed a control diet; groups 2, 3 and 4 were fed a HFD. In addition, group 3 was co-administered with 10 mg/kg/day of CP extract (HFD + CP) and group 4 with a solution of 5 mg/kg/day metformin (HFD + M) for 90 days. ResultsBody weight gain and serum triglycerides were significantly decreased in the HFD + CP group compared with the HFD and HFD + M groups. Glucose tolerance increased in the HFD + CP compared with the HFD group. Administration with CP extract reduced adipose tissue lipolysis and lipid accumulation in liver of HFD + CP rats with respect to HFD and HFD + M groups. Histological examinations showed that the area of the adipocytes in WAT and the area of lipid vesicles in BAT were significantly smaller in the HFD + CP group than in the HFD and HFD + M groups. ConclusionAdministration of a CP extract prevented glucose intolerance and hepatic lipid accumulation in rats fed a HFD in association with reduced adipocyte hypertrophy, demonstrating potential antidiabetic properties.

Cold-Pressed Nigella Sativa Oil Standardized to 3% Thymoquinone Potentiates Omega-3 Protection against Obesity-Induced Oxidative Stress, Inflammation, and Markers of Insulin Resistance Accompanied with Conversion of White to Beige Fat in Mice.

Excessive lipid accumulation in white adipose tissue (WAT) results in adipocyte hypertrophy and chronic low-grade inflammation, which is the major cause of obesity-associated insulin resistance and consequent metabolic disease. The development of beige adipocytes in WAT (browning of WAT) increases energy expenditure and has been considered as a novel strategy to counteract obesity. Thymoquinone (TQ) is the main bioactive quinone derived from the plant Nigella Sativa and has antioxidative and anti-inflammatory capacities. Fish oil omega 3 (ω3) enhances both insulin sensitivity and glucose homeostasis in obesity, but the involved mechanisms remain unclear. The aim of this study is to explore the effects of TQ and ω3 PUFAs (polyunsaturated fatty acids) on obesity-associated inflammation, markers of insulin resistance, and the metabolic effects of adipose tissue browning. 3T3-L1 cells were cultured to investigate the effects of TQ and ω3 on the browning of WAT. C57BL/6J mice were fed a high-fat diet (HFD), supplemented with 0.75% TQ, and 2% ω3 in combination for eight weeks. In 3T3-L1 cells, TQ and ω3 reduced lipid droplet size and increased hallmarks of beige adipocytes such as uncoupling protein-1 (UCP1), PR domain containing 16 (PRDM16), fibroblast growth factor 21 (FGF21), Sirtuin 1 (Sirt1), Mitofusion 2 (Mfn2), and heme oxygenase 1 (HO-1) protein expression, as well as increased the phosphorylation of Protein Kinase B (AKT) and insulin receptors. In the adipose tissue of HFD mice, TQ and ω3 treatment attenuated levels of inflammatory adipokines, Nephroblastoma Overexpressed (NOV/CCN3) and Twist related protein 2 (TWIST2), and diminished adipocyte hypoxia by decreasing HIF1α expression and hallmarks of beige adipocytes such as UCP1, PRDM16, FGF21, and mitochondrial biogenesis markers Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), Sirt1, and Mfn2. Increased 5′ adenosine monophosphate-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) phosphorylation and HO-1 expression were observed in adipose with TQ and ω3 treatment, which led to increased pAKT and pIRS1 Ser307 expression. In addition to the adipose, TQ and ω3 also increased inflammation and markers of insulin sensitivity in the liver, as demonstrated by increased phosphorylated insulin receptor (pIR tyr972), insulin receptor beta (IRβ), UCP1, and pIRS1 Ser307 and reduced NOV/CCN3 expression. Our data demonstrate the enhanced browning of WAT from TQ treatment in combination with ω3, which may play an important role in decreasing obesity-associated insulin resistance and in reducing the chronic inflammatory state of obesity.

Lacto-Fermented Cauliflower Fungus (Sparassis crispa) Ameliorates Hepatic Steatosis by Activating Beta-Oxidation in Diet-Induced Obese Zebrafish.

Sparassis crispa (SC), known as cauliflower mushroom, possesses a wide variety of health-promoting properties and a high content of β-glucans. Its nutritional properties are enhanced by fermentation. In this study, we examined the efficacy of Lactobacillus-fermented (lacto-fermented) SC against obesity using a zebrafish model. We first fermented SC by Lactobacillus paracasei, denoted as lacto-fermented SC (L-SC), for 48 h and then orally administered SC or L-SC to diet-induced obese zebrafish for 4 weeks. Results demonstrated that the L-SC group (20 μg/gBW/day) significantly (P < .01) suppressed body weight gain and ameliorated lipid accumulation in liver tissues, whereas SC did not exhibit antiobesity effects. We further performed expression analysis of genes related to lipid metabolism in the liver and visceral adipose tissues (VAT) in L-SC-administered fish. In liver tissues, L-SC upregulated (P < .05) expression of genes involved in peroxisome proliferator-activated receptor alpha pathways, suggesting that the lipid-lowering property of L-SC is caused by activation of beta-oxidation. In VAT, L-SC did not show significant changes between the experimental groups. No difference was observed between the β-glucan contents of SC (43.8 g/100 g) and L-SC (44.3 g/100 g); however, β-glucan levels in the hot-water extracts increased 20-fold in L-SC (37.2 g/100 g) compared with those in SC (1.8 g/100 g). In summary, lacto-fermentation of SC enhances its lipid-lowering property and can prevent hepatic steatosis through activation of beta-oxidation. Dietary supplementation of fermented L-SC as a functional food may be suitable for obesity prevention and reduction in the prevalence of obesity-related diseases.

Ablation of Iah1, a candidate gene for diet-induced fatty liver, does not affect liver lipid accumulation in mice.

Nonalcoholic fatty liver disease (NAFLD) is a pathological condition caused by excess triglyceride deposition in the liver. The SMXA-5 severe fatty liver mouse model has been established from the SM/J and A/J strains. To explore the genetic factors involved in fatty liver development in SMXA-5 mice, we had previously performed quantitative trait locus (QTL) analysis, using (SM/J×SMXA-5)F2 intercross mice, and identified Fl1sa on chromosome 12 (centromere-53.06 Mb) as a significant QTL for fatty liver. Furthermore, isoamyl acetate-hydrolyzing esterase 1 homolog (Iah1) was selected as the most likely candidate gene for Fl1sa. Iah1 gene expression in fatty liver-resistant A/J-12SM mice was significantly higher than in fatty liver-susceptible A/J mice. These data indicated that the Iah1 gene might be associated with fatty liver development. However, the function of murine Iah1 remains unknown. Therefore, in this study, we created Iah1 knockout (KO) mice with two different backgrounds [C57BL/6N (B6) and A/J-12SM (A12)] to investigate the relationship between Iah1 and liver lipid accumulation. Liver triglyceride accumulation in Iah1-KO mice of B6 or A12 background did not differ from their respective Iah1-wild type mice under a high-fat diet. These results indicated that loss of Iah1 did not contribute to fatty liver. On the other hands, adipose tissue dysfunction causes lipid accumulation in ectopic tissues (liver, skeletal muscle, and pancreas). To investigate the effect of Iah1 deficiency on white adipose tissue, we performed DNA microarray analysis of epididymal fat in Iah1-KO mice of A12 background. This result showed that Iah1 deficiency might decrease adipokines Sfrp4 and Metrnl gene expression in epididymal fat. This study demonstrated that Iah1 deficiency did not cause liver lipid accumulation and that Iah1 was not a suitable candidate gene for Fl1sa.

SUN-663 Dietary Coconut Oil Mitigates Features of Metabolic Syndrome in Obese Females

Forty percent of American women are obese and at risk for metabolic syndrome. Coconut oil alters circulating lipid levels and improves glucose homeostasis in lean individuals, yet, whether it can exert these same beneficial effects on cardiometabolic health in obese individuals is unknown. We hypothesized that female pigs fed a high fat diet with 5% coconut oil would have improvements in features of metabolic syndrome (i.e., dyslipidemia) compared to female mini-pigs fed a high fat diet with 5% lard. We fed female pigs 2200 kcal of a control (n=6), 5000 kcal of a lard high fat (WSD; n=5), or 5000 kcal of a coconut oil high fat (COC; n=6) diet for a total of 9 estrous cycles (~ 7.5 months). Fasting blood was collected at the 1st, 7th (C 7), and 9th (C 9) estrous cycle. After C 7, an intravenous glucose tolerance test (IVGTT) was performed. Weights and morphometric measurements were taken weekly. Tissue was collected for histology at C 9. WSD females (15.14 ± 1.85 mg/dL) had a greater increase in fasting glucose as compared to COC (3.51 ± 4.31 mg/dL) and C females (0.45 ± 3.32 mg/dL; p<0.05). COC females tended to be more glucose tolerant (p=0.07) and had lower serum insulin concentrations in response to a glucose bolus (p<0.001) than WSD females. COC (82.6 ± 1.1 kg) and WSD females (85.4 ± 1.0 kg) weighed more (C: 61.9 ± 1.1 kg; p<0.0001) and had larger abdominal circumferences (COC: 122.4 ± 0.8 cm; WSD: 117.4 ± 1.0 cm) than control females (102.6 ± 1.0 cm; p<0.0001). WSD females were the most dyslipidemic, with the greatest increase in triglycerides (C: 0.33 ± 1.5 mg/dL; COC: 7.71 ± 3.0 mg/dL; WSD: 17.25 ± 3.0 mg/dL; p=0.03) and HDL:cholesterol (C: 3.44 ± 0.22; COC: 5.00 ± 0.36; WSD: 6.00 ± 0.42; p=0.05) as compared control and COC females. COC females had increased plasma docosahexaenoic acid (C: -0.128 ± 0.291; COC: 0.262 ± 0.260; WSD: -0.732 ± 0.274; p<0.01) and decreased arachidonic acid (C: 2.418 ± 0.744; COC: -4.561 ± 0.666; WSD: -2.068 ± 0.702; p<0.01). COC females (131.26 ± 10.0 μm) had a decreased average omental adipocyte diameter as compared to WSD females (160.06 ± 10.31 μm; p=0.05). COC females (7.3 ± 0.80 %) had less hepatic lipid accumulation as measured by oil red o stain than WSD females (9.2 ± 1.1 %; p=0.05). These data demonstrate that small amounts of dietary coconut oil, even as a part of a high fat diet, can mitigate features of metabolic syndrome and decrease hepatic and visceral adipose tissue lipid accumulation in obese females.

Organotypic Culture of Mouse Meibomian Gland: A Novel Model to Study Meibomian Gland Dysfunction In Vitro.

PurposeMeibomian glands are essential in maintaining the integrity and health of the ocular surface. Meibomian gland dysfunction (MGD), mainly induced by ductal occlusion, is considered as the major cause of dry eye disease. In this study, a novel in vitro model was established for investigating the role of inflammation in the process of MGD.MethodsMouse tarsal plates were removed from eyelids after dissection and explants were cultured during various time ranging from 24 to 120 hours. Meibomian gland epithelial cells were further enzymatically digested and dissociated from tarsal plates before culturing. Both explants and cells were incubated in different media with or without serum or azithromycin (AZM). Furthermore, explants were treated with IL-1β or vehicle for 48 hours. Analyses for tissue viability, histology, biomarker expression, and lipid accumulation were performed with hematoxylin and eosin (H&E) staining, immunofluorescence staining, and Western blot.ResultsHigher viability was preserved when explants were cultured on Matrigel with immediate addition of culture medium. The viability, morphology, biomarker expression, and function of meibomian glands were preserved in explants cultured for up to 72 hours. Lipid accumulation and peroxisome proliferator-activated receptor γ (PPARγ) expression increased in both explants and cells cultured in media containing serum or AZM. Treatment with IL-1β induced overexpression of Keratin (Krt) 1 in meibomian gland ducts.ConclusionsIntervention with pro-inflammatory cytokine IL-1β induces hyperkeratinization in meibomian gland ducts in vitro. This novel organotypic culture model can be used for investigating the mechanism of MGD.

Urtica dioica Whole Vegetable as a Functional Food Targeting Fat Accumulation and Insulin Resistance-a Preliminary Study in a Mouse Pre-Diabetic Model.

The shoot of Urtica dioica is used in several cultures as a vegetable or herb. However, not much has been studied about the potential of this plant when consumed as a whole food/vegetable rather than an extract for dietary supplements. In a 12-week dietary intervention study, we tested the effect of U. dioica vegetable on high fat diet induced obesity and insulin resistance in C57BL/6J mice. Mice were fed ad libitum with isocaloric diets containing 10% fat or 45% fat with or without U. dioica. The diet supplemented with U. dioica attenuated high fat diet induced weight gain (p < 0.005; n = 9), fat accumulation in adipose tissue (p < 0.005; n = 9), and whole-body insulin resistance (HOMA-IR index) (p < 0.001; n = 9). Analysis of gene expression in skeletal muscle showed no effect on the constituents of the insulin signaling pathway (AKT, IRS proteins, PI3K, GLUT4, and insulin receptor). Notable genes that impact lipid or glucose metabolism and whose expression was changed by U. dioica include fasting induced adipocyte factor (FIAF) in adipose and skeletal muscle, peroxisome proliferator-activated receptor-α (Ppar-α) and forkhead box protein (FOXO1) in muscle and liver, and Carnitine palmitoyltransferase I (Cpt1) in liver (p < 0.01). We conclude that U. dioica vegetable protects against diet induced obesity through mechanisms involving lipid accumulation and glucose metabolism in skeletal muscle, liver, and adipose tissue.

Lipid Nephrotoxicity and Increased Risk of Nephrolithiasis in Model of Estrogen Deficiency

Menopause is a period during which women tend to gain body fat. Estrogen deficiency is proposed to impact body fat composition and energy balance in these women by influencing the levels of leptin, an adipocyte‐derived hormone that acts primarily on the central nervous system. Specifically, lipid nephrotoxicity increases the risk for kidney disease and nephrolithiasis due to renal lipid accumulation and overly acidic urinary pH. Mechanisms underlying these kidney disturbances and extent of their effects when women become estrogen deficient (i.e. post‐menopausal) are not well‐defined. Utilizing an estrogen deficient (i.e. ovariectomized) rodent model, we hypothesize that central leptin receptor activation regulates renal function by augmenting the accumulation of renal lipids and urinary pH acidification. We measured the glomerular filtration rate (GFR) by creatinine clearance and protein level of the neutrophil gelatinase‐associated lipocalin (NGAL), an early biomarker of kidney injury, by immunohistochemistry. An increase in creatinine clearance (from 1.3 ml/min to 2.3 ml/min) and protein levels of NGAL (over 90% increase in both glomeruli and tubules) was measured in ovariectomized adult female rats when compared with their sham‐operated controls. Treatment with leptin receptor antagonist (LAN‐6, 3μg/day), delivered for four weeks into the lateral ventricle by an osmotic pump, significantly attenuated these effects. Furthermore, we determined that perirenal fat accumulation was markedly higher in the same estrogen deficiency model when compared with the sham‐operated control. Perirenal fat accumulation has been associated with lipid accumulation in renal tissues and excess of intrarenal lipid is increasingly recognized to contribute to kidney injury through lipotoxicity. A significant accumulation of renal lipid, tested using oil red O staining, was detected in the renal tubules of the ovariectomized animals when compared with their controls. We also found significant acidification of urinary pH and decreased protein expression of a key player in urinary pH regulation, Na/H exchanger‐3 (NHE3), in ovariectomized animals when compared with their controls. Renal lipid accumulation, urinary pH acidification and decrease in NHE3 expression were all partially reversed by blocking activation of central leptin receptors. We propose that: 1. An increase in GFR combined with kidney injury presupposes kidney dysfunction, 2. infiltration of renal lipid leads to renal injury, through lipotoxicity, 3. urinary pH acidification and reduction of NHE3 expression increases the risk of nephrolithiasis. Taken together, these findings suggest that leptin plays a key role in the development of menopausal‐associated kidney disease.

Biological Functions for STARD5 Assessed Using stard5−/− Mice

STARD5 belongs to the StAR‐Related Lipid‐transfer (START) domain protein superfamily and is proposed to contribute to intracellular non‐vesicular cholesterol transport. STARD5 is a soluble sterol‐binding protein that is induced by endoplasmic reticulum (ER) stress, yet testing for a biological function needs to consider the conflicting data on whether the preferred ligand for STARD5 is cholesterol and 25‐hydroxycholesterol or bile acids, including chenodeoxycholic acid (CDCA). Our work has characterized STARD5 expression in kidney and we reported that STARD5 and cholesterol levels are increased in kidneys of the OVE diabetic mouse model compare to wild‐type controls, and that STARD5 is increased in cell culture by the ER stress inducer tunicamycin. Cholesterol accumulation in the ER is known to promote ER stress; however, the significance of the association between elevated renal cholesterol, ER stress, and STARD5 in diabetic kidney remains to be determined. We propose STARD5 indirectly controls cholesterol homeostasis via modulating farnesoid X receptor (FXR) activity. FXR is a nuclear receptor that binds CDCA and activation of FXR contributes to maintaining fatty acid and cholesterol homeostasis in diabetic kidney disease. To test whether STARD5 affects FXR signaling we generated whole body STARD5 knock‐out mice (stard5−/−) using CRISPR‐Cas9 and compared the FXR target gene expression in the knockout and WT kidney. There was no difference in body weight, liver weight/body weight ratio, or kidney weight/body weight ratio between stard5−/− mice compared to wild‐type littermate controls (WT) (male mice n = 5 WT; n= 7 stard5−/−). We will present data from current studies focused on determining whether there are differences in tissue histology, lipid accumulation, and FXR target gene expression between stard5−/− mice and WT littermate controls.Support or Funding InformationBiochemistry &amp; Molecular Genetics Departmental Funds to BJC

Sinapic acid induces the expression of thermogenic signature genes and lipolysis through activation of PKA/CREB signaling in brown adipocytes

Lipid accumulation in white adipose tissue is the key contributor to the obesity and orchestrates numerous metabolic health problems such as type 2 diabetes, hypertension, atherosclerosis, and cancer. Nonetheless, the prevention and treatment of obesity are still inadequate. Recently, scientists found that brown adipose tissue (BAT) in adult humans has functions that are diametrically opposite to those of white adipose tissue and that BAT holds promise for a new strategy to counteract obesity. In this study, we evaluated the potential of sinapic acid (SA) to promote the thermogenic program and lipolysis in BAT. SA treatment of brown adipocytes induced the expression of brown-adipocyte activation–related genes such as Ucp1, Pgc-1α, and Prdm16. Furthermore, structural analysis and western blot revealed that SA upregulates protein kinase A (PKA) phosphorylation with competitive inhibition by a pan-PKA inhibitor, H89. SA binds to the adenosine triphosphate (ATP) site on the PKA catalytic subunit where H89 binds specifically. PKA-cat-α1 gene–silencing experiments confirmed that SA activates the thermogenic program via a mechanism involving PKA and cyclic AMP response element–binding protein (CREB) signaling. Moreover, SA treatment promoted lipolysis via a PKA/p38-mediated pathway. Our findings may allow us to open a new avenue of strategies against obesity and need further investigation.

Tissue-specific analysis of lipid species in Drosophila during overnutrition by UHPLC-MS/MS and MALDI-MSI

Diets high in calories can be used to model metabolic diseases, including obesity and its associated comorbidities, in animals. Drosophila melanogaster fed high-sugar diets (HSDs) exhibit complications of human obesity including hyperglycemia, hyperlipidemia, insulin resistance, cardiomyopathy, increased susceptibility to infection, and reduced longevity. We hypothesize that lipid storage in the high-sugar-fed fly's fat body (FB) reaches a maximum capacity, resulting in the accumulation of toxic lipids in other tissues or lipotoxicity. We took two approaches to characterize tissue-specific lipotoxicity. Ultra-HPLC-MS/MS and MALDI-MS imaging enabled spatial and temporal localization of lipid species in the FB, heart, and hemolymph. Substituent chain length was diet dependent, with fewer odd chain esterified FAs on HSDs in all sample types. By contrast, dietary effects on double bond content differed among organs, consistent with a model where some substituent pools are shared and others are spatially restricted. Both di- and triglycerides increased on HSDs in all sample types, similar to observations in obese humans. Interestingly, there were dramatic effects of sugar feeding on lipid ethers, which have not been previously associated with lipotoxicity. Taken together, we have identified candidate endocrine mechanisms and molecular targets that may be involved in metabolic disease and lipotoxicity.

EID1 suppresses lipid accumulation by inhibiting the expression of GPDH in 3T3‐L1 preadipocytes

The imbalance between food intake and energy expenditure causes high accumulation of triglycerides in adipocytes. Obesity is related with the increased lipid accumulation in white adipose tissue, which is a major risk factor for the development of metabolic disorders, such as type 2 diabetes and cardiovascular disease. This study highlights the role of E1A-like inhibitor of differentiation 1 (EID1) in the modulation of adipogenesis through the downregulation of glycerol-3-phosphate dehydrogenase (GPDH), which is a key enzyme in the synthesis of triglycerides and is considered to be a marker of adipogenesis. By analyzing DNA microarray data, we found that when EID1 is overexpressed in preadipocytes (3T3-L1 cells) during adipocyte differentiation, EID1 inhibits lipid accumulation through the downregulation of GPDH. In contrast, EID1 is not involved in the regulation of intracellular glucose via the translocation of glucose transporter. A confocal image analysis showed that EID1 is located in the nucleus of preadipocytes in the form of speckles, which could be involved as a regulator of the transcriptional process. We further confirmed that EID1 is able to bind to the promoter sequence of GPDH in the nucleus. These findings provide a molecular explanation for the inhibitory effect of EID1 on lipid accumulation in adipocytes.