Hormone-sensitive Lipase Protein Research Articles

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.

Cloning and Molecular Characterization of HSL and Its Expression Pattern in HPG Axis and Testis during Different Stages in Bactrian Camel.

Hormone-sensitive lipase (HSL) is a key enzyme in animal fat metabolism and is involved in the rate-limiting step of catalyzing the decomposition of fat and cholesterol. It also plays an important regulatory role in maintaining seminiferous epithelial structure, androgen synthesis and primordial germ cell differentiation. We previously reported that HSL is involved the synthesis of steroids in Bactrian camels, although it is unclear what role it plays in testicular development. The present study was conducted to characterize the biological function and expression pattern of the HSL gene in the hypothalamic pituitary gonadal (HPG) axis and the development of testis in Bactrian camels. We analyzed cloning of the cDNA sequence of the HSL gene of Bactrian camels by RT-PCR, as well as the structural features of HSL proteins, using bioinformatics software, such as ProtParam, TMHMM, Signal P 4.1, SOPMA and MEGA 7.0. We used qRT-PCR, Western blotting and immunofluorescence staining to clarify the expression pattern of HSL in the HPG axis and testis of two-week-old (2W), two-year-old (2Y), four-year-old (4Y) and six-year-old (6Y) Bactrian camels. According to sequence analysis, the coding sequence (CDS) region of the HSL gene is 648 bp in length and encodes 204 amino acids. According to bioinformatics analysis, the nucleotide and amino acid sequence of Bactrian camel HSL are most similar to those of Camelus pacos and Camelus dromedarius, with the lowest sequence similarity with Mus musculus. In adult Bactrian camel HPG axis tissues, both HSL mRNA and protein expression were significantly higher in the testis than in other tissues (hypothalamus, pituitary and pineal tissues) (p < 0.05). The expression of mRNA in the testis increased with age and was the highest in six-year-old testis (p < 0.01). The protein expression levels of HSL in 2Y and 6Y testis were clearly higher than in 2W and 4Y testis tissues (p < 0.01). Immunofluorescence results indicate that the HSL protein was mainly localized in the germ cells, Sertoli cells and Leydig cells from Bactrian camel testis, and strong positive signals were detected in epididymal epithelial cells, basal cells, spermatocytes and smooth muscle cells, with partially expression in hypothalamic glial cells, pituitary suspensory cells and pineal cells. According to the results of gene ontology (GO) analysis enrichment, HSL indirectly regulates the anabolism of steroid hormones through interactions with various targets. Therefore, we conclude that the HSL gene may be associated with the development and reproduction of Bactrian camels in different stages of maturity, and these results will contribute to further understanding of the regulatory mechanisms of HSL in Bactrian camel reproduction.

Hormone-sensitive lipase is localized at synapses and is necessary for normal memory functioning in mice

Hormone-sensitive lipase (HSL) is mainly present in adipose tissue where it hydrolyzes diacylglycerol. Although expression of HSL has also been reported in the brain, its presence in different cellular compartments is uncertain, and its role in regulating brain lipid metabolism remains hitherto unexplored. We hypothesized that HSL might play a role in regulating the availability of bioactive lipids necessary for neuronal function and therefore investigated whether dampening HSL activity could lead to brain dysfunction. In mice, we found HSL protein and enzymatic activity throughout the brain, localized within neurons and enriched in synapses. HSL-null mice were then analyzed using a battery of behavioral tests. Relative to wild-type littermates, HSL-null mice showed impaired short-term and long-term memory, yet preserved exploratory behaviors. Molecular analysis of the cortex and hippocampus showed increased expression of genes involved in glucose utilization in the hippocampus, but not cortex, of HSL-null mice compared with controls. Furthermore, lipidomics analyses indicated an impact of HSL deletion on the profile of bioactive lipids, including a decrease in endocannabinoids and eicosanoids that are known to modulate neuronal activity, cerebral blood flow, and inflammation processes. Accordingly, mild increases in the expression of proinflammatory cytokines in HSL mice compared with littermates were suggestive of low-grade inflammation. We conclude that HSL has a homeostatic role in maintaining pools of lipids required for normal brain function. It remains to be tested, however, whether the recruitment of HSL for the synthesis of these lipids occurs during increased neuronal activity or whether HSL participates in neuroinflammatory responses.

Effect of Resistance Exercise on the Lipolysis Pathway in Obese Pre- and Postmenopausal Women.

Physical exercise may stimulate lipolytic activity within adipose tissue. Furthermore, resistance exercise may contribute to the more efficient reduction in adipose tissue mass and prevent the accumulation thereof in obese women. The purpose of this study was to examine the effects of regular resistance exercise for 12 weeks on the lipolysis pathway in women with obesity. Twenty-three pre- and postmenopausal women with body fat percentages of 30% or more were divided into the premenopausal group (n = 9) and the postmenopausal group (n = 14). All subjects participated in resistance exercise training for 12 weeks. Anthropometric and physical fitness tests were performed on all participants. Protein analyses were performed on extracted subcutaneous fatty tissue, and changes in the relevant protein levels in the samples were analyzed by Western blotting. All serum samples were submitted for enzyme-linked immunosorbent assay measurements of adipocyte factors. After 12 weeks, the adipose triglyceride lipase, monoacylglycerol lipase, and perilipin1 protein levels were significantly lower in the postmenopausal group than in the premenopausal group. The hormone-sensitive lipase protein levels were significantly higher in the postmenopausal group than in the premenopausal group. In addition, leptin concentrations were significantly decreased after resistance exercise in the postmenopausal group. Adiponectin concentrations were significantly increased after resistance exercise in both groups. These findings indicate that regular resistance exercise is effective in reducing the weight and body fat of obese premenopausal women, and in the secretion of adiponectin. On the other hand, postmenopausal women were found to have redeced weight and body fat, and were found to be positive for the secretion of adipokine factors. In addition, positive changes in lipolysis pathway factors in adipose tissue promote lipid degradation and reduce fat mass. Thus, regular resistance exercise shows positive changes in the lipolysis pathway more effectively in weight and body fat reduction in postmenopausal women than in premenopausal women.

Garlic Scape Extract Decreases Adipogenesis and Lipogenesis by Activating AMK-Activated Protein Kinase in 3T3-L1 Adipocytes

Abstract Objectives Excessive fat accumulation in the body, indicated as obesity causes development of other metabolic diseases, such as diabetes and cardiovascular diseases. Due to limitations of current strategies such as long-term engagement and high cost, new strategies to reduce the prevalence of obesity are needed. Garlic scape (Allium sativum L.) is the flower bud of the garlic plant that is removed to promote the growth of the bulb. Although most of garlic scape are trashed as a byproduct of garlic in the farm, it is still edible and includes various phytochemicals to improve human health. The purpose of this study was to investigate anti-obesity effect of garlic scape and its mechanism using 3T3-L1 cells. Methods Garlic scape extract (GSE) was prepared by solvent extraction using 80% methanol (v/v). 3T3-L1 cells, mouse embryonic fibroblast cells that mimic preadipocytes, were incubated with GSE during the differentiation. Total RNA and proteins from the cells were extracted. The expression of genes related to lipid metabolism such as peroxisome proliferator-activated receptor (PPAR) γ, CCAAT/enhancer-binding protein (C\EBP) α and β, adipocyte protein (aP) 2, acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), sterol regulated element binding protein (SREBP) 1c, and carnitine palmitoyltransferase (CPT) 1α was determined using a quantitative PCR. The expression of proteins such as hormone sensitive lipase (HSL), ACC, and AMPK-activated protein kinase (AMPK) was measured using a western blot. Effect of GSE on lipid accumulation were visualized and quantified using Oil Red O staining. Results GSE decreased the expression of genes related to adipogenesis (PPARγ, C\EBPα, and C\EBPβ) and lipogenesis (ACC, FAS, and SREBP1c) whereas HSL and CPT1α genes and proteins related to lipolysis and fatty acid oxidation were not changed. Phosphorylation on both AMPK and ACC were increased. Adipocytes that were treated with GSE showed reduced lipid accumulation. Conclusions GSE inhibits fat accumulation in white adipocytes by decreasing adipogenesis and lipogenesis through possibly a AMPK pathway. Garlic scape may be a potential candidate to improve obese conditions. Funding Sources This work was supported by USDA.

Liraglutide attenuates renal tubular ectopic lipid deposition in rats with diabetic nephropathy by inhibiting lipid synthesis and promoting lipolysis

Liraglutide is a new hypoglycemic drug. The previous studies have shown that liraglutide can improve the renal outcomes of patients with type 2 diabetes. Recently, it was approved by the U.S. FDA for used as a weight-loss drugs. However, the mechanism of its improvements of renal function in diabetic nephropathy patients is unclear. In addition, the effect of liraglutide on lipid metabolism is also not clear. The purpose of this study was to investigate the effects and mechanisms of liraglutide in alleviating ectopic lipid deposition (ELD) in rats with diabetic nephropathy (DN). Male Sprague-Dawley (SD) rats were treated with high-fat diet + unilateral nephrectomy + low-dose STZ combined to establish a DN rat model to evaluate the lipid-lowering effect of liraglutide. Liraglutide at 0.4 mg/kg/d were subcutaneous injected into for 12 weeks (DN + liraglutide group). After the DN rat model was established, body weight loss, 24-h urine volume increasing, serum triglycerides (TG) and serum total cholesterol (TCh) increasing, ectopic lipid droplet deposition in renal tubular increasing, mesangial proliferation in renal tissue were observed in DN rats. The treatment with liraglutide could reduce the body weight and the average daily food intake of the rats, as well as TG, TCh, and ectopic lipid droplet deposition in renal tubular. Metabolomics result showed that serum differential metabolites between the DN - vehicle control group and the DN + liraglutide group mainly included serine, threonine, phenylalanine, oxyproline, threonine, sorbitol, glyceryl monostearate, glycerol monostearate, and β-d-glucuronic acid. Moreover, liraglutide can reduce plasma lipid levels in DN rats by increasing the products of lipolysis including 1-monopalmitin and 1-monoostearin. Immunohistochemistry and Western blot showed that the expression levels of lipid synthesis-related sterol regulatory element binding protein 1 (SREBP-1) and fatty acid synthase (FAS) were significantly increased, and lipolysis-related adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) were significantly decreased both in the renal tissue of DN rats and PA-induced HK-2 cells (lipid droplet accumulation model). However, liraglutide can attenuate renal tubular ectopic lipid deposition in DN rats by inhibiting SREBP-1, FAS and increasing ATGL, HSL protein expression level, and also ameliorated PA-induced lipid accumulation in renal tubular epithelial cells. These lipid metabolism changes were attributed to liraglutide by upregulating AMP-activated protein kinase (AMPK) phosphorylation in the kidney of DN rats. Collectively, these findings confirm that liraglutide inhibits lipid synthesis and promotes lipolysis to attenuate renal ectopic lipid deposition in DN rats by promoting AMPK phosphorylation.

Bifenthrin Induces Fat Deposition by Improving Fatty Acid Uptake and Inhibiting Lipolysis in Mice.

Chemical residues in the environment are considered to be important factors that cause obesity. Bifenthrin is one of the pyrethroid pesticides and is widely used worldwide. However, its effect on adipose tissue is ill-defined. Here, we administered bifenthrin/corn oil to adult C57BL/6 mice by gavage. After 6 weeks, the bifenthrin treatment significantly increased their body weight (P = 0.015) and fat mass (P < 0.001). Then we identified 246 differently expressed proteins by proteomic analysis, and they were highly involved in fatty acid uptake and lipid metabolism processes. Interestingly, protein hormone-sensitive lipase and adipose triacylglyceride lipase were downregulated while lipoprotein lipase is upregulated after bifenthrin treatment. Similar effects in 3T3-L1 cells treated with bifenthrin validated the in vivo results. Thus, this study suggests that long-term exposure to low-dose bifenthrin induces fat deposition in mice by improving fatty acid uptake and inhibiting lipolysis, and it may cause obesity in humans.

The N-terminal His-tag affects the triglyceride lipase activity of hormone-sensitive lipase in testis.

The sterility of hormone-sensitive lipase (HSL) knockout mice clearly shows the link between lipid metabolism and spermatogenesis. However, which substrate or product of this multifunctional lipase affects spermatogenesis is unclear. We found that an HSL protein with a His-tag at the N-terminus preserved the normal hydrolase activity of cholesteryl ester (CE) but the triglyceride lipase (TG) activity significantly decreased in vitro. Therefore, mice with this functionally incomplete HSL (His-HSL) were produced on a background of HSL deficiency (HSL-/- h). As a result, HSL-/- h testis has an 8.65-fold higher CE activity than wild-type testis but a twofold higher TG activity than wild-type testis. To compare His-HSL and wild-type HSL in vitro and in vivo, we confirmed that the His-tag significantly suppressed HSL TG activity. From our results, we believe that TG activity was affected by the His-tag insertion, but CE activity was not influenced. Furthermore, the His-tag protected HSL from binding to the inhibitor BAY. From our study, TG activity and BAY binding sites were affected by N-terminal His-tag insertion.

Feeding influences adipose tissue responses to exercise in overweight men.

Feeding profoundly affects metabolic responses to exercise in various tissues, but the effect of feeding status on human adipose tissue responses to exercise has never been studied. Ten healthy overweight men aged 26 ± 5 yr (mean ± SD) with a waist circumference of 105 ± 10 cm walked at 60% of maximum oxygen uptake under either fasted or fed conditions in a randomized, counterbalanced design. Feeding comprised 648 ± 115 kcal 2 h before exercise. Blood samples were collected at regular intervals to examine changes in metabolic parameters and adipokine concentrations. Adipose tissue samples were obtained at baseline and 1 h after exercise to examine changes in adipose tissue mRNA expression and secretion of selected adipokines ex vivo. Adipose tissue mRNA expression of pyruvate dehydrogenase kinase isozyme 4 (PDK4), adipose triglyceride lipase, hormone-sensitive lipase (HSL), fatty acid translocase/CD36, glucose transporter type 4 (GLUT4), and insulin receptor substrate 2 (IRS2) in response to exercise were lower in fed compared with fasted conditions (all P ≤ 0.05). Postexercise adipose IRS2 protein was affected by feeding (P ≤ 0.05), but Akt2, AMPK, IRS1, GLUT4, PDK4, and HSL protein levels were not different. Feeding status did not impact serum and ex vivo adipose secretion of IL-6, leptin, or adiponectin in response to exercise. This is the first study to show that feeding before acute exercise affects postexercise adipose tissue gene expression, and we propose that feeding is likely to blunt long-term adipose tissue adaptation to regular exercise.

Specific visible radiation facilitates lipolysis in mature 3T3-L1 adipocytes via rhodopsin-dependent β3-adrenergic signaling

The regulation of fat metabolism is important for maintaining functional and structural tissue homeostasis in biological systems. Reducing excessive lipids has been an important concern due to the concomitant health risks caused by metabolic disorders such as obesity, adiposity and dyslipidemia. A recent study revealed that unlike conventional care regimens (e.g., diet or medicine), low-energy visible radiation (VR) regulates lipid levels via autophagy-dependent hormone-sensitive lipase (HSL) phosphorylation in differentiated human adipose-derived stem cells. To clarify the underlying cellular and molecular mechanisms, we first verified the photoreceptor and photoreceptor-dependent signal cascade in nonvisual 3T3-L1 adipocytes. For a better understanding of the concomitant phenomena that result from VR exposure, mature 3T3-L1 adipocytes were exposed to four different wavelengths of VR (410, 505, 590 and 660nm) in this study. The results confirmed that specific VR wavelengths, especially 505nm than 590nm, increase intracellular cyclic adenosine monophosphate (cAMP) levels and decrease lipid droplets. Interestingly, the mRNA and protein levels of the Opn2 (rhodopsin) photoreceptor increased after VR exposure in mature 3T3-L1 adipocytes. Subsequent treatment of mature 3T3-L1 adipocytes at a specific VR wavelength induced rhodopsin- and β3-adrenergic receptor (AR)-dependent lipolytic responses that consequently led to increases in intracellular cAMP and phosphorylated HSL protein levels. Our study indicates that photoreceptors are expressed and exert individual functions in nonvisual cells, such as adipocytes. We suggest that the VR-induced photoreceptor system could be a potential therapeutic target for the regulation of lipid homeostasis in a non-invasive manner.

Placental lipase expression in pregnancies complicated by preeclampsia: a case-control study.

BackgroundPreeclampsia (PE) is associated with maternal and neonatal morbidity and mortality. In PE, the physiological hyperlipidaemia of pregnancy is exaggerated. The purpose of this study was to examine the expression of adipose triglyceride lipase (ATGL), hormone sensitive lipase (HSL), lipoprotein lipase (LPL) and endothelial lipase (EL) in pregnancies complicated by PE.MethodsPlacentae were collected from 16 women with PE and 20 women with uncomplicated pregnancies matched for maternal prepregnancy BMI and gestational age of delivery. Gene and protein expression of the placental lipases were measured by Q-PCR and Western blot. DNA methylation of the promoter of LPL was assessed by bisulfite sequencing. Lipase localisation and activity were analysed.ResultsGene expression of all lipases was significantly reduced, as was HSL protein level in women with PE. All lipases were localised to trophoblasts and endothelial cells in PE and control placentae. There was no difference in methylation of the LPL promoter between PE and control placentae. Lipase activity was not altered in placentae from women with PE.ConclusionThese results suggest that the decreased placental lipase gene but not protein expression or lipase activity, which is associated with late-onset PE is not a major contributor to the abnormal lipids seen in PE.

Habitual exercise training acts as a physiological stimulator for constant activation of lipolytic enzymes in rat primary white adipocytes

It is widely accepted that lipolysis in adipocytes are regulated through the enzymatic activation of both hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) via their phosphorylation events. Accumulated evidence shows that habitual exercise training (HE) enhances the lipolytic response in primary white adipocytes with changes in the subcellular localization of lipolytic molecules. However, no study has focused on the effect that HE exerts on the phosphorylation of both HSL and ATGL in primary white adipocytes. It has been shown that the translocation of HSL from the cytosol to lipid droplet surfaces requires its phosphorylation at Ser-563. In primary white adipocytes obtained from HE rats, the level of HSL and ATGL proteins was higher than that in primary white adipocytes obtained from sedentary control (SC) rats. In HE rats, the level of phosphorylated ATGL and HSL was also significantly elevated compared with that in SC rats. These differences were confirmed by Phos-tag SDS-PAGE, a technique used to measure the amount of total phosphorylated proteins. Our results suggest that HE can consistently increase the activity of both lipases, thereby enhancing the lipolysis in white fat cells. Thus, HE helps in the prevention and treatment of obesity-related diseases by enhancing the lipolytic capacity.

PPARγ, FAS, HSL mRNA and protein expression during Tan sheep fat-tail development

article i nfo Background: The objective of this study was to investigate proliferator-activated receptor (PPARγ), fatty acid synthase (FAS) and hormone-sensitive lipase (HSL) mRNA and protein expression in fat tails of Tan sheep. Rams from different developmental stages (aged 3, 6, 9, 12, 15 and 18 months) were selected, and their tail measurements including length (L), width (W) and girth (G) were recorded. The mRNA and protein expressions of PPARγ, FAS and HSL were examined by quantitative real-time polymerase chain reaction (PCR) and Western blot. Results: The tail measurements increased with age. We observed no significant differences (P N 0.05) of PPARγ mRNA expression between ages 9 and 15 months, and between 12 and 15 months; FAS mRNA expression levels at each developmental stage were observed significantly in Tan sheep (P b 0.05); HSL mRNA expression with no significant differences were only observed between 6 and 15 months (P N 0.05). Significant differences (P b 0.05) of PPARγ, FAS and HSL protein expressions at each developmental stage were observed in Tan sheep. Conclusion: We observed that the mRNA expression patterns of PPARγ and FAS decreased first before they increased again and then this process repeated. Conversely, the mRNA expression patterns of HSL increased first before they decreased and then this process repeated. The protein expression patterns of PPARγ and FAS decreased first before they increased again and then this process repeated. Conversely, the protein expression pattern of HSL increased first before it decreased again and then increased again.

Lipolytic Effect of Eumicrotremus orbis Water Extracts in Differentiated 3T3-L1 Adipocytes

In this study, we investigated the effects of Eumicrotremus orbis water extracts (EOWE) on lipolysis in differentiatied 3T3-L1 adipocytes and its mechanism. It was observed that there was no cytotoxicity for adipocytes of EOWE. The content of glycerol released in cell culture medium increased dependent on sample concentration. In differentiated 3T3-L1 adipocytes treated EOWE, hormone sensitive lipase (HSL) and phosphorylated HSL (p-HSL) protein level increased by approximately 3.43 and 1.77 times as compared to the controls. But, adipose triglyceride lipase (ATGL) protein level did not effect as compared to the controls. Treated EOWE inhibited the protein expression of perilipin A. In other word, it is judged to be due to, a content of glycerol released in cell culture medium increased through not only increase of HSL, p-HSL and p-PKA protein level, but inhibit of perilipin A. Therefore, our results suggest that EOWE may induce lipoylsis by increasing the protein levels of HSL, p-HSL and p-PKA.

Null Mutation in Hormone-Sensitive Lipase Gene and Risk of Type 2 Diabetes

BackgroundLipolysis regulates energy homeostasis through the hydrolysis of intracellular triglycerides and the release of fatty acids for use as energy substrates or lipid mediators in cellular processes. Genes encoding proteins that regulate energy homeostasis through lipolysis are thus likely to play an important role in determining susceptibility to metabolic disorders.MethodsWe sequenced 12 lipolytic-pathway genes in Old Order Amish participants whose fasting serum triglyceride levels were at the extremes of the distribution and identified a novel 19-bp frameshift deletion in exon 9 of LIPE, encoding hormone-sensitive lipase (HSL), a key enzyme for lipolysis. We genotyped the deletion in DNA from 2738 Amish participants and performed association analyses to determine the effects of the deletion on metabolic traits. We also obtained biopsy specimens of abdominal subcutaneous adipose tissue from 2 study participants who were homozygous for the deletion (DD genotype), 10 who were heterozygous (ID genotype), and 7 who were noncarriers (II genotype) for assessment of adipose histologic characteristics, lipolysis, enzyme activity, cytokine release, and messenger RNA (mRNA) and protein levels.ResultsCarriers of the mutation had dyslipidemia, hepatic steatosis, systemic insulin resistance, and diabetes. In adipose tissue from study participants with the DD genotype, the mutation resulted in the absence of HSL protein, small adipocytes, impaired lipolysis, insulin resistance, and inflammation. Transcription factors responsive to peroxisome-proliferator–activated receptor γ (PPAR-γ) and downstream target genes were down-regulated in adipose tissue from participants with the DD genotype, altering the regulation of pathways influencing adipogenesis, insulin sensitivity, and lipid metabolism.ConclusionsThese findings indicate the physiological significance of HSL in adipocyte function and the regulation of systemic lipid and glucose homeostasis and underscore the severe metabolic consequences of impaired lipolysis. (Funded by the National Institutes of Health and others).

MmPPOX Inhibits Mycobacterium tuberculosis Lipolytic Enzymes Belonging to the Hormone-Sensitive Lipase Family and Alters Mycobacterial Growth

Lipid metabolism plays an important role during the lifetime of Mycobacterium tuberculosis, the causative agent of tuberculosis. Although M. tuberculosis possesses numerous lipolytic enzymes, very few have been characterized yet at a biochemical/pharmacological level. This study was devoted to the M. tuberculosis lipolytic enzymes belonging to the Hormone-Sensitive Lipase (HSL) family, which encompasses twelve serine hydrolases closely related to the human HSL. Among them, nine were expressed, purified and biochemically characterized using a broad range of substrates. In vitro enzymatic inhibition studies using the recombinant HSL proteins, combined with mass spectrometry analyses, revealed the potent inhibitory activity of an oxadiazolone compound, named MmPPOX. In addition, we provide evidence that MmPPOX alters mycobacterial growth. Overall, these findings suggest that the M. tuberculosis HSL family displays important metabolic functions, thus opening the way to further investigations linking the involvement of these enzymes in mycobacterial growth.

Adipose triglyceride lipase and hormone-sensitive lipase protein expression in subcutaneous adipose tissue is decreased after an isoenergetic low-fat high-complex carbohydrate diet in the metabolic syndrome

The objective was to determine the contribution of dietary fat quantity and composition to lipolysis and lipolytic gene expression in humans in relation to obesity, insulin resistance, and the metabolic syndrome (MetS). Men and women with the MetS were randomly assigned to one of four isoenergetic diets: a high-fat saturated fat diet (n=10), a high-fat monounsaturated fat diet (n=7), and two low-fat high-complex carbohydrate (LFHCC) diets, one supplemented with 1.24g/day long-chain n-3 PUFA (LFHCC: n=7, LFHCCn-3: n=8). Subcutaneous adipose tissue biopsies were taken before and after the 12-week dietary intervention period. ATGL and HSL mRNA and protein expression was determined. Whole body rate of appearance of free fatty acids (RaFFA) was determined by intravenous infusion of [2H2]-palmitate in a subgroup of men (n=20). Adipose tissue ATGL and HSL mRNA and protein expression was not affected by alterations in dietary fat composition. Pooled analysis comparing the low- and high-fat diets showed that ATGL and HSL protein expression was significantly reduced after the LFHCC diets (P=.04), irrespective of long-chain n-3 PUFA. Moreover, LFHCC diets lowered fasting insulin, HOMAIR, and (LDL)-cholesterol concentrations (P≤.05). Changes in ATGL and HSL protein expression was positively associated with changes in whole body RaFFA (P<.03). The low-fat high-complex carbohydrate diets reduced ATGL and HSL protein expression and significantly improved circulating lipids and insulin sensitivity. Under isoenergetic conditions, dietary fat quantity, rather than composition, may be most important for modulating subcutaneous adipose tissue ATGL and HSL protein expression.

The Calcium-Sensing Receptor Affects Fat Accumulation via Effects on Antilipolytic Pathways in Adipose Tissue of Rats Fed Low-Calcium Diets

Low-calcium intake is associated with increased risk of obesity, but the mechanism underlying this is not clear. We previously reported that the calcium-sensing receptor (CaSR) plays an important role in modulating the expression of rate-limiting lipolysis enzymes in human adipocytes. In the present study, rats were fed diets containing normal [0.50% (NC)], low [0.30% (LC)], or very low [0.15% (VLC)] calcium for 15 wk. Ten rats of each group were killed at wk 5, 10, and 15 of the intervention. The LC-fed rats had greater visceral fat mass, lower serum FFA and glycerol concentrations, and greater CaSR expression in white adipose tissue than did those fed the NC diet at wk 10 and 15. Hormone-sensitive lipase (HSL) and adipose TG lipase (ATGL) protein levels were lower, whereas fatty acid synthase mRNA in white adipose tissue was greater in the LC-fed rats compared with the NC-fed rats. These differences from the NC group were greater in the VLC group than in the LC group at wk 15. In vitro experiments showed that 1,25-dihydroxycholecalciferol stimulated the expression of CaSR through the nuclear vitamin D receptor (nVDR). This resulted in an antilipolytic effect by increasing intracellular calcium, decreasing the intracellular cAMP level, and downregulating HSL and ATGL protein expression in adipocytes. These effects were suppressed by either nVDR or CaSR small-interfering RNA. These results suggest that CaSR affects fat accumulation by mediating antilipolytic pathways in adipose tissue of rats fed low-calcium diets.

Rye bran alkylresorcinols suppress adipocyte lipolysis and hormone‐sensitive lipase activity

The effects of alkylresorcinols (ARs) isolated from rye bran on adipocyte lipolysis, hormone-sensitive lipase activity and phosphorylation and on phosphorylation of protein kinase A substrates were studied. Preincubation with ARs for 18 h suppressed catecholamine-stimulated lipolysis in 3T3-L1 adipocytes. Furthermore, phosphorylation of hormone-sensitive lipase (HSL), a key lipase responsible for stimulated lipolysis, and phosphorylation of protein kinase A substrates, were diminished after preincubation with ARs, whereas HSL protein expression was unaltered. ARs were also shown to inhibit HSL activity in an in vitro assay.

Hormone-sensitive lipase protein expression and extent of phosphorylation in subcutaneous and retroperitoneal adipose tissues in the periparturient dairy cow

Lipomobilization is essential for dairy cows to balance the energy requirement for milk production in early lactation. This study aimed to determine the role of hormone-sensitive lipase (HSL) and its activation by phosphorylation at Ser 660 (HSLp660) and 563 (HSLp563) in different adipose tissue depots as influenced by time and postpartum diet in dairy cows. Biopsy samples were obtained from s.c. (SCAT) and retroperitoneal (RPAT) adipose tissues of 20 Holstein cows 21 d prepartum, and 1 and 21 d postpartum. After d 1 postpartum, cows were randomly assigned to 2 groups (n=10). Groups received diets with either a concentrate-to-roughage ratio on a dry matter basis of 30:70% (low-concentrate, LC, group) or 60:40% (high-concentrate group), fed until the third biopsy sampling 21 d postpartum. Dry matter intake, milk yield, and milk composition were recorded. Blood samples were taken weekly, starting 21 d prepartum and analyzed for nonesterified fatty acids, β-hydroxybutyrate (BHBA), glucose, and insulin. Protein expression of HSL and its extent of phosphorylation in adipose tissue were measured by semiquantitative Western blotting. Total HSL expression was lower in both adipose tissues 1 d after calving compared with prepartum sampling (SCAT: 4.10±0.5 vs. 2.4±0.3; RPAT: 11.1±1.3 vs. 6.6±1.1). Phosphorylation at Ser 660 was higher 21 d postpartum compared with 21 d prepartum in RPAT (2.9±0.3 vs. 4.6±0.6). Phosphorylation at Ser 563 was higher 21 d postpartum than 21 d prepartum in SCAT (0.6±0.1 vs. 3.9±1.1), and in RPAT a difference was observed between 21 d prepartum and 1 d postpartum (1.0±0.1 vs. 3.3. ± 0.6). On d 21 postpartum, the LC group showed a lower extent of Ser 563 phosphorylation in RPAT (3.9±0.8 vs.10.0±1.9) and a higher concentration of serum BHBA (0.77±0.05 vs. 0.47±0.11) than did the high-concentrate group. An inhibitory influence of higher BHBA concentrations on HSL phosphorylation in the LC group could be a possible explanation. On comparing RPAT to SCAT, HSL expression and the extent of Ser 660 and 563 phosphorylation was higher in RPAT at 21 d prepartum (HSL: 4.1±0.5 vs. 11.1±1.2; HSLp660 1.3±0.2 vs. 2.9±0.3; HSLp563: 0.6±0.1 vs. 1.0±0.1). In conclusion, the postpartum feeding regimen influenced the phosphorylation pattern, especially in RPAT, implying a regulatory role for different phosphorylation sites in adaptive lipolysis of dairy cows. It is suggested that RPAT is more sensitive to periparturient challenges than is SCAT.