Acanthoic acid suppresses lipin1/2 via TLR4 and IRAK4 signalling pathways in EtOH- and lipopolysaccharide-induced hepatic lipogenesis.

OBJECTIVES: In alcoholic liver disease, alcohol and lipopolysaccharide (LPS) are major stimulation factors of hepatic lipogenesis. Our objective was to determine the protective mechanism of acanthoic acid (AA) in EtOH- and LPS-induced hepatic lipogenesis. METHODS: HSC-T6 cells were treated with ethanol (200 mm) plus LPS (1 µg/ml) for 1 h, followed by AA (10 or 20 µm) for another 6 h. C57BL/6 mice were pretreated with of AA (20 and 40 mg/kg) or equal volume of saline and then exposed to three doses of ethanol (5 g/kg body weight) within 24 h. The mice were sacrificed at 6 h after the last ethanol dosing. KEY FINDINGS: Acanthoic acid significantly decreased the expressions of α-SMA, collagen-I, SREBP-1, and lipin1/2 induced, also decreased fat droplets caused by EtOH/LPS. AA treatment decreased the protein expressions of TLR4, CD14, IRAK4, TRAF3, p-TAK1 and NF-κB increased by EtOH/LPS on HSC cells. Results in vivo were consistent with results in vitro. CONCLUSIONS: Our data demonstrated that AA might modulate hepatic fibrosis and lipid deposition in HSC-T6 cell stimulated with ethanol combined with LPS by decreasing lipin1/2 via TLR4 and IRAK4 signalling pathways, and AA might be considered as a potential therapeutic candidate for alcoholic liver disease.

Alliin attenuates 1, 3-dichloro-2-propanol-induced lipogenesis in HepG2 cells through activation of the AMP-activated protein kinase-dependent pathway.

Accumulating evidence reveals the association of 1, 3-dichloro-2-propanol (1, 3-DCP) exposure and lipogenesis. Alliin, the most abundant sulphur compound in garlic, has been demonstrated to exhibit hypoglycemic, antioxidant and anti-inflammatory activities. Here, we showed that alliin attenuated lipogenesis induced by 1,3-DCP and that the reduction was due to activation of the AMPK pathway. HepG2 cells exposed to 1,3-DCP exhibited significant increase of triglyceride(TG) and total cholesterol(TC), and alliin reduced the accumulation. Most importantly, alliin could up-regulate the phosphorylation of AMPK and down-regulate protein and gene expressions of SREBP-1; FAS; SREBP-2;HMGCR in 1,3-DCP-induced HepG2 cells. The results demonstrated that alliin was effective on attenuating 1,3-DCP-induced lipogenesis via activation of the AMPK-SREBPs signaling pathway in HepG2 cells.

Perhexiline activates KLF14 and reduces atherosclerosis by modulating ApoA-I production.

Recent genome-wide association studies have revealed that variations near the gene locus encoding the transcription factor Krüppel-like factor 14 (KLF14) are strongly associated with HDL cholesterol (HDL-C) levels, metabolic syndrome, and coronary heart disease. However, the precise mechanisms by which KLF14 regulates lipid metabolism and affects atherosclerosis remain largely unexplored. Here, we report that KLF14 is dysregulated in the liver of 2 dyslipidemia mouse models. We evaluated the effects of both KLF14 overexpression and genetic inactivation and determined that KLF14 regulates plasma HDL-C levels and cholesterol efflux capacity by modulating hepatic ApoA-I production. Hepatic-specific Klf14 deletion in mice resulted in decreased circulating HDL-C levels. In an attempt to pharmacologically target KLF14 as an experimental therapeutic approach, we identified perhexiline, an approved therapeutic small molecule presently in clinical use to treat angina and heart failure, as a KLF14 activator. Indeed, in WT mice, treatment with perhexiline increased HDL-C levels and cholesterol efflux capacity via KLF14-mediated upregulation of ApoA-I expression. Moreover, perhexiline administration reduced atherosclerotic lesion development in apolipoprotein E-deficient mice. Together, these results provide comprehensive insight into the KLF14-dependent regulation of HDL-C and subsequent atherosclerosis and indicate that interventions that target the KLF14 pathway should be further explored for the treatment of atherosclerosis.

ChIP-seq and in vivo transcriptome analyses of the Aspergillus fumigatus SREBP SrbA reveals a new regulator of the fungal hypoxia response and virulence.

The Aspergillus fumigatus sterol regulatory element binding protein (SREBP) SrbA belongs to the basic Helix-Loop-Helix (bHLH) family of transcription factors and is crucial for antifungal drug resistance and virulence. The latter phenotype is especially striking, as loss of SrbA results in complete loss of virulence in murine models of invasive pulmonary aspergillosis (IPA). How fungal SREBPs mediate fungal virulence is unknown, though it has been suggested that lack of growth in hypoxic conditions accounts for the attenuated virulence. To further understand the role of SrbA in fungal infection site pathobiology, chromatin immunoprecipitation followed by massively parallel DNA sequencing (ChIP-seq) was used to identify genes under direct SrbA transcriptional regulation in hypoxia. These results confirmed the direct regulation of ergosterol biosynthesis and iron uptake by SrbA in hypoxia and revealed new roles for SrbA in nitrate assimilation and heme biosynthesis. Moreover, functional characterization of an SrbA target gene with sequence similarity to SrbA identified a new transcriptional regulator of the fungal hypoxia response and virulence, SrbB. SrbB co-regulates genes involved in heme biosynthesis and demethylation of C4-sterols with SrbA in hypoxic conditions. However, SrbB also has regulatory functions independent of SrbA including regulation of carbohydrate metabolism. Loss of SrbB markedly attenuates A. fumigatus virulence, and loss of both SREBPs further reduces in vivo fungal growth. These data suggest that both A. fumigatus SREBPs are critical for hypoxia adaptation and virulence and reveal new insights into SREBPs' complex role in infection site adaptation and fungal virulence.

Mycobacterium leprae intracellular survival relies on cholesterol accumulation in infected macrophages: a potential target for new drugs for leprosy treatment.

We recently showed that Mycobacterium leprae (ML) is able to induce lipid droplet formation in infected macrophages. We herein confirm that cholesterol (Cho) is one of the host lipid molecules that accumulate in ML-infected macrophages and investigate the effects of ML on cellular Cho metabolism responsible for its accumulation. The expression levels of LDL receptors (LDL-R, CD36, SRA-1, SR-B1, and LRP-1) and enzymes involved in Cho biosynthesis were investigated by qRT-PCR and/or Western blot and shown to be higher in lepromatous leprosy (LL) tissues when compared to borderline tuberculoid (BT) lesions. Moreover, higher levels of the active form of the sterol regulatory element-binding protein (SREBP) transcriptional factors, key regulators of the biosynthesis and uptake of cellular Cho, were found in LL skin biopsies. Functional in vitro assays confirmed the higher capacity of ML-infected macrophages to synthesize Cho and sequester exogenous LDL-Cho. Notably, Cho colocalized to ML-containing phagosomes, and Cho metabolism impairment, through either de novo synthesis inhibition by statins or depletion of exogenous Cho, decreased intracellular bacterial survival. These findings highlight the importance of metabolic integration between the host and bacteria to leprosy pathophysiology, opening new avenues for novel therapeutic strategies to leprosy.

Silencing diacylglycerol kinase-theta expression reduces steroid hormone biosynthesis and cholesterol metabolism in human adrenocortical cells.

Diacylglycerol kinase theta (DGKθ) plays a pivotal role in regulating adrenocortical steroidogenesis by synthesizing the ligand for the nuclear receptor steroidogenic factor 1 (SF1). In response to activation of the cAMP signaling cascade nuclear DGK activity is rapidly increased, facilitating PA-mediated, SF1-dependent transcription of genes required for cortisol and dehydroepiandrosterone (DHEA) biosynthesis. Based on our previous work identifying DGKθ as the enzyme that produces the agonist for SF1, we generated a tetracycline-inducible H295R stable cell line to express a short hairpin RNA (shRNA) against DGKθ and characterized the effect of silencing DGKθ on adrenocortical gene expression. Genome-wide DNA microarray analysis revealed that silencing DGKθ expression alters the expression of multiple genes, including steroidogenic genes, nuclear receptors and genes involved in sphingolipid, phospholipid and cholesterol metabolism. Interestingly, the expression of sterol regulatory element binding proteins (SREBPs) was also suppressed. Consistent with the suppression of SREBPs, we observed a down-regulation of multiple SREBP target genes, including 3-hydroxy-3-methylglutary coenzyme A reductase (HMG-CoA red) and CYP51, concomitant with a decrease in cellular cholesterol. DGKθ knockdown cells exhibited a reduced capacity to metabolize PA, with a down-regulation of lipin and phospholipase D (PLD) isoforms. In contrast, suppression of DGKθ increased the expression of several genes in the sphingolipid metabolic pathway, including acid ceramidase (ASAH1) and sphingosine kinases (SPHK). In summary, these data demonstrate that DGKθ plays an important role in steroid hormone production in human adrenocortical cells.

Enhanced endoplasmic reticulum SERCA activity by overexpression of hepatic stimulator substance gene prevents hepatic cells from ER stress-induced apoptosis.

Although the potential pathogenesis of nonalcoholic fatty liver disease (NAFLD) is unclear, increasing evidence indicates that endoplasmic reticulum (ER) stress may link free fatty acids to NAFLD. Since we previously reported that hepatic stimulator substance (HSS) could protect the liver from steatosis, this study is aimed to investigate whether HSS protection could be related with its inhibition on ER stress. The HSS gene was stably transfected into BEL-7402 hepatoma cells and effectively expressed in ER. The palmitic acid (PA)-induced heptocyte lipotoxicity was reproduced in the HSS-transfected cells, and HSS alleviation of the ER stress and apoptosis were subsequently examined. The results showed that PA treatment led to a heavy accumulation of fatty acids within the cells and a remarkable increase in reactive oxygen species (ROS). However, in the HSS-expressing cells, production of ROS was inhibited and ER stress-related marker glucose-regulated protein 78 (GRP-78), sterol regulatory element-binding protein (SREBP), anti-phospho-PRK-1ike ER kinase (p-PERK), anti-phospho-eukaryotic initiation factor 2α (p-eIF2α), and anti-C/EBP homologous protein (CHOP) were downregulated compared with the wild-type or mutant HSS-transfected cells. Furthermore, PA treatment severely impaired the activity of sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA), leading to imbalanced calcium homeostasis during ER stress, which could be rescued in the HSS-trasfected cells. The protection provided by HSS to the SERCA is identical to that observed with N-acetyl-l-cysteine (NAC) and sodium dimercaptopropane sulfonate (Na-DMPS), which are two typical free radical scavengers. As a consequence, the rate of ER stress-mediated apoptosis in the HSS-expressing cells was significantly reduced. In conclusion, the protective effect of HSS against ER stress may be associated with the removal of ROS to restore the activity of the SERCA.

Mycobacterium leprae intracellular survival relies on cholesterol accumulation in infected macrophages: a potential target for new drugs for leprosy treatment

We recently showed that Mycobacterium leprae (ML) is able to induce lipid droplet formation in infected macrophages. We herein confirm that cholesterol (Cho) is one of the host lipid molecules that accumulate in ML-infected macrophages and investigate the effects of ML on cellular Cho metabolism responsible for its accumulation. The expression levels of LDL receptors (LDL-R, CD36, SRA-1, SR-B1, and LRP-1) and enzymes involved in Cho biosynthesis were investigated by qRT-PCR and/or Western blot and shown to be higher in lepromatous leprosy (LL) tissues when compared to borderline tuberculoid (BT) lesions. Moreover, higher levels of the active form of the sterol regulatory element-binding protein (SREBP) transcriptional factors, key regulators of the biosynthesis and uptake of cellular Cho, were found in LL skin biopsies. Functional in vitro assays confirmed the higher capacity of ML-infected macrophages to synthesize Cho and sequester exogenous LDL-Cho. Notably, Cho colocalized to ML-containing phagosomes, and Cho metabolism impairment, through either de novo synthesis inhibition by statins or depletion of exogenous Cho, decreased intracellular bacterial survival. These findings highlight the importance of metabolic integration between the host and bacteria to leprosy pathophysiology, opening new avenues for novel therapeutic strategies to leprosy.

Interaction of RAS activation and lipid disorders accelerates the progression of glomerulosclerosis.

BACKGROUND: The activation of the renin-angiotensin system (RAS) and lipid disorders are major risk factors in progressive chronic kidney disease. This study aimed to investigate the potential synergistic mechanisms of RAS activation and lipid disorders that contribute to glomerulosclerosis. MATERIALS AND METHODS: Human renal mesangial cells (HMCs) were treated with 10(-7) mol/L angiotensin II (Ang II) or with 30 µg/ml cholesterol and 1 µg/ml 25-hydroxycholesterol (lipid loading) for 24 hours. Lipid accumulation in the cells was evaluated by Oil Red O staining and intracellular cholesterol quantitative assays. The gene and protein expression of molecules in the low-density lipoprotein receptor (LDLr) pathway, the RAS family, and the extracellular matrix were examined by real-time polymerase chain reaction and Western blotting. The translocation of sterol regulatory element-binding protein (SREBP) cleavage activating protein (SCAP), which escorts SREBP-2 from the endoplasmic reticulum (ER) to the Golgi, was examined by immunofluorescent staining. RESULTS: Ang II increased lipid droplet accumulation in HMCs. Further analysis revealed that Ang II increased the mRNA and protein expression of LDLr, SCAP, and SREBP-2. This increase was correlated with an enhanced translocation of the SCAP/SREBP-2 complex from the ER to the Golgi in HMCs that was induced by Ang II, thereby activating LDLr gene transcription. Interestingly, lipid loading increased the mRNA and protein expression of angiotensinogen, Ang II, renin, angiotensin-converting enzyme, angiotensin II type 1 receptor, and type 2 receptor in HMCs with increased mRNA and protein expression of collagen I, α-smooth muscle actin, and fibronectin. CONCLUSIONS: This study demonstrates that the interaction of RAS activation and lipid disorders accelerates the progression of glomerulosclerosis.

Regulation of bile acid, cholesterol, and fatty acid synthesis in chicken primary hepatocytes by different concentrations of T0901317, an agonist of liver X receptors.

Liver X receptors (LXRs) are members of the nuclear receptor family of transcription factors. They play a crucial role in lipid metabolism processes such as bile acid and fatty acid synthesis, as well as minor or limited roles in the regulation of cholesterol synthesis and uptake in mammals. In avian species, however, little is known about the role of LXRs except for the fact that they are involved in the stimulation of fatty acid synthesis. In this study, we characterize the expression profile of genes related to bile acid, cholesterol, and fatty acid synthesis and VLDL secretion in chicken primary hepatocytes treated with T0901317, a synthetic agonist of LXR. The activity of chicken cholesterol 7α hydroxylase (CYP7A1), a key enzyme in bile acid synthesis, mRNA expression, and bile acid excretion, was stimulated by supplementation of the culture medium with a low concentration (0.01 µM) of T0901317. In contrast, the levels of sterol regulatory element binding protein (SREBP)-1, fatty acid synthase mRNA, and VLDL-triacylglycerol in cells cultured in the presence of a high concentration (10 µM) of T0901317 were higher than those cultured in zero or low concentrations of T0901317. These results suggest that cellular responses to this LXR agonist were similar to those present in mammals. A novel finding of this study concerned changes to the regulation of cholesterol synthesis and uptake in chicken hepatocytes treated with T0901317. Levels of SREBP-2,3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) and low-density lipoprotein receptor (LDLr) mRNA expression increased as a function of increasing T0901317 (up to 1.0 µM), but remained similar to those in cells cultured under control conditions when the concentration of T0901317 was increased to 10 µM. These results suggest that LXRs play an important role in cholesterol synthesis and uptake in chicken hepatocytes and, as such, differ to findings in mammals where the effect of LXR agonists on cholesterol synthesis plays only a minor role in the regulation of cellular sterol homeostasis.

The glucosylceramide synthase inhibitor N-(5-adamantane-1-yl-methoxy-pentyl)-deoxynojirimycin induces sterol regulatory element-binding protein-regulated gene expression and cholesterol synthesis in HepG2 cells.

Recent findings have implicated glycosphingolipids as modulators of insulin receptor activity. Studies with C57BL/6J ob/ob mice have shown that insulin sensitivity is enhanced by the synthetic hydrophobic iminosugar N-(5-adamantane-1-yl-methoxy-pentyl)-deoxynojirimycin (AMP-DNM) that inhibits glucosylceramide synthase. Here, we treated the liver hepatoma cell line HepG2 with AMP-DNM, resulting in a 70% reduction of glycosphingolipids, and we analyzed the effect on gene expression. Using whole human genome 44K oligonucleotide arrays, we identified 89 genes that were significantly (p < 0.01) up- or down-regulated by AMP-DNM treatment. Of the 56 up-regulated genes, 17 were direct target genes for transcription factors sterol regulatory element-binding protein (SREBP) 1 or SREBP2, which activate genes in the sterol biosynthesis pathway. An increase in cholesterol production rate confirmed that the induction of SREBP target genes seen at the mRNA level resulted in activation of the cholesterol biosynthesis pathway. It is interesting to note that the cholesterol content of the cells did not increase. It is noteworthy that no effects were found on expression of genes related to cell receptor signaling pathways, neither on toxicity nor cell growth. Our findings indicate that inhibition of glucosylceramide synthase with AMP-DNM leads to activation of SREBP target genes and synthesis of cholesterol in HepG2 cells.

Pharmacologic inhibition of site 1 protease activity inhibits sterol regulatory element-binding protein processing and reduces lipogenic enzyme gene expression and lipid synthesis in cultured cells and experimental animals.

Sterol regulatory element-binding proteins (SREBPs) are major transcriptional regulators of cholesterol, fatty acid, and glucose metabolism. Genetic disruption of SREBP activity reduces plasma and liver levels of cholesterol and triglycerides and insulin-stimulated lipogenesis, suggesting that SREBP is a viable target for pharmacological intervention. The proprotein convertase SREBP site 1 protease (S1P) is an important posttranscriptional regulator of SREBP activation. This report demonstrates that 10 microM PF-429242 (Bioorg Med Chem Lett 17:4411-4414, 2007), a recently described reversible, competitive aminopyrrolidineamide inhibitor of S1P, inhibits endogenous SREBP processing in Chinese hamster ovary cells. The same compound also down-regulates the signal from an SRE-luciferase reporter gene in human embryonic kidney 293 cells and the expression of endogenous SREBP target genes in cultured HepG2 cells. In HepG2 cells, PF-429242 inhibited cholesterol synthesis, with an IC(50) of 0.5 microM. In mice treated with PF-429242 for 24 h, the expression of hepatic SREBP target genes was suppressed, and the hepatic rates of cholesterol and fatty acid synthesis were reduced. Taken together, these data establish that small-molecule S1P inhibitors are capable of reducing cholesterol and fatty acid synthesis in vivo and, therefore, represent a potential new class of therapeutic agents for dyslipidemia and for a variety of cardiometabolic risk factors associated with diabetes, obesity, and the metabolic syndrome.

Activation of sterol regulatory element-binding protein 1c and fatty acid synthase transcription by hepatitis C virus non-structural protein 2.

Transcriptional factor sterol regulatory element-binding protein 1c (SREBP-1c) activates the transcription of lipogenic genes, including fatty acid synthase (FAS). Hepatitis C virus (HCV) infection is often associated with lipid accumulation within the liver, known as steatosis in the clinic. The molecular mechanisms of HCV-associated steatosis are not well characterized. Here, we showed that HCV non-structural protein 2 (NS2) activated SREBP-1c transcription in human hepatic Huh-7 cells as measured by using a human SREBP-1c promoter-luciferase reporter plasmid. We further showed that sterol regulatory element (SRE) and liver X receptor element (LXRE) in the SREBP-1c promoter were involved in SREBP-1c activation by HCV NS2. Furthermore, expression of HCV NS2 resulted in the upregulation of FAS transcription. We also showed that FAS upregulation by HCV NS2 was SREBP-1-dependent since deleting the SRE sequence in a FAS promoter and expressing a dominant-negative SREBP-1 abrogated FAS promoter upregulation by HCV NS2. Taken together, our results suggest that HCV NS2 can upregulate the transcription of SREBP-1c and FAS, and thus is probably a contributing factor for HCV-associated steatosis.

SREBPs: the crossroads of physiological and pathological lipid homeostasis.

The uptake, biosynthesis and metabolism of cholesterol and other lipids are exquisitely regulated by feedback and feed-forward pathways in organisms ranging from Caenorhabditis elegans to humans. As endoplasmic reticulum (ER) membrane-embedded transcription factors that are activated in the Golgi apparatus, sterol regulatory element-binding proteins (SREBPs) are central to the intracellular surveillance of lipid catabolism and de novo biogenesis. The biosynthesis of SREBP proteins, their migration from the ER to the Golgi compartment, intra-membrane proteolysis, nuclear translocation and trans-activation potential are tightly controlled in vivo. Here we summarize recent studies elucidating the transcriptional and post-transcriptional regulation of SREBP-1c through nutrition and the action of hormones, particularly insulin, and the resulting implications for dyslipidemia of obesity, metabolic syndrome and type 2 diabetes.

Effects of fish oil and conjugated linoleic acids on expression of target genes of PPAR alpha and sterol regulatory element-binding proteins in the liver of laying hens.

In mammals, (n-3) PUFA and conjugated linoleic acids (CLA) act as activators of PPAR alpha and alter nuclear concentrations of sterol regulatory element-binding proteins (SREBP) in the liver, and thereby influence hepatic lipid catabolism and synthesis. In this study, we investigated the hypothesis that (n-3) PUFA and CLA exert similar effects in the liver of laying hens. Thirty hens (64 weeks old) were fed diets containing 30 g/kg of sunflower oil (control), fish oil (salmon oil) or CLA in TAG form (containing predominantly cis-9, trans-11 CLA and trans-10, cis-12 CLA) for 5 weeks. Hens fed fish oil had a higher expression of some PPAR alpha target genes and a lower nuclear concentration of SREBP-2 in the liver and lower concentrations of cholesterol and TAG in plasma than control hens. Nuclear concentration of SREBP-1 and its target genes involved in lipogenesis were not altered in hens fed fish oil. Hens fed CLA had increased concentrations of TAG and cholesterol in the liver. However, their mRNA levels of PPAR alpha target genes and nuclear concentrations of SREBP-1 and SREBP-2 as well as mRNA levels of their target genes in the liver were largely unchanged compared to control hens. The results of this study suggest that (n-3) PUFA cause a moderate activation of PPAR alpha and lower cholesterol synthesis but do not impair fatty acid synthesis in the liver of laying hens. CLA lead to an accumulation of TAG and cholesterol in the liver of hens by mechanisms to be elucidated in further studies.

Hypocholesterolemic mechanism of Chlorella: Chlorella and its indigestible fraction enhance hepatic cholesterol catabolism through up-regulation of cholesterol 7alpha-hydroxylase in rats.

Chlorella powder (CP) has a hypocholesterolemic effect and high bile acid-binding capacity; however, its effects on hepatic cholesterol metabolism are still unclear. In the present study, male Wistar rats were divided into four groups and fed a high sucrose + 10% lard diet (H), an H + 10% CP diet (H+CP), an H + 0.5% cholesterol + 0.25% sodium cholate diet (C), or a C + 10% CP diet (C+CP) for 2 weeks. CP decreased serum and liver cholesterol levels significantly in rats fed C-based diets, but did not affect these parameters in rats fed H-based diets. CP increased the hepatic mRNA level and activity of cholesterol 7alpha-hydroxylase (CYP7A1). CP increased hepatic HMG-CoA reductase (HMGR) activity in the rats fed H-based diets, but not in rats fed C-based diets. CP did not affect hepatic mRNA levels of sterol 27-hydroxylase, HMGR, low-density lipoprotein (LDL) receptor, scavenger receptor class B1, ATP-binding cassette (ABC) A1, ABCG5, or ABCB11. Furthermore, the effect of a 3.08% Chlorella indigestible fraction (CIF, corresponding to 10% CP) on hepatic cholesterol metabolism was determined using the same animal models. CIF also decreased serum and liver cholesterol levels significantly in rats fed C-based diets. CIF increased hepatic CYP7A1 mRNA levels. These results suggest that the hypocholesterolemic effect of CP involves enhancement of cholesterol catabolism through up-regulation of hepatic CYP7A1 expression and that CIF contributes to the hypocholesterolemic effect.

Drug-induced activation of SREBP-controlled lipogenic gene expression in CNS-related cell lines: marked differences between various antipsychotic drugs.

BACKGROUND: The etiology of schizophrenia is unknown, but neurodevelopmental disturbances, myelin- and oligodendrocyte abnormalities and synaptic dysfunction have been suggested as pathophysiological factors in this severe psychiatric disorder. Cholesterol is an essential component of myelin and has proved important for synapse formation. Recently, we demonstrated that the antipsychotic drugs clozapine and haloperidol stimulate lipogenic gene expression in cultured glioma cells through activation of the sterol regulatory element-binding protein (SREBP) transcription factors. We here compare the action of chlorpromazine, haloperidol, clozapine, olanzapine, risperidone and ziprasidone on SREBP activation and SREBP-controlled gene expression (ACAT2, HMGCR, HMGCS1, FDPS, SC5DL, DHCR7, LDLR, FASN and SCD1) in four CNS-relevant human cell lines. RESULTS: There were marked differences in the ability of the antipsychotic drugs to activate the expression of SREBP target genes, with clozapine and chlorpromazine as the most potent stimulators in a context of therapeutically relevant concentrations. Glial-like cells (GaMg glioma and CCF-STTG1 astrocytoma cell lines) displayed more pronounced drug-induced SREBP activation compared to the response in HCN2 human cortical neurons and SH-SY5Y neuroblastoma cells, indicating that antipsychotic-induced activation of lipogenesis is most prominent in glial cells. CONCLUSION: Our present data show a marked variation in the ability of different antipsychotics to induce SREBP-controlled transcriptional activation of lipogenesis in cultured human CNS-relevant cells. We propose that this effect could be relevant for the therapeutic efficacy of some antipsychotic drugs.

Distribution and metabolism of dihomo-gamma-linolenic acid (DGLA, 20:3n-6) by oral supplementation in rats.

We compared the dietary effects of dihomo-gamma-linolenic acid (DGLA) contained in the DGLA oil produced by a fungus with gamma-linolenic acid (GLA) on the fatty acid composition. Wistar rats were fed with three kinds of oil for two weeks as follows: (i) control group: corn oil; (ii) GLA group: borage oil; (iii) DGLA group: DGLA oil/safflower oil = 55:45. The DGLA concentrations in the liver, serum, and brain of the DGLA group were higher than those of the GLA oil group. We also examined the dose effect of DGLA. The DGLA levels in the liver, serum, and brain significantly increased with increasing dosage of DGLA in the diet. DGLA administration significantly increased the ratio of PGE1/PGE2 in the rat plasma. The mechanism for GLA administration to improve atopic eczema is thought to involve an increase in the concentration of DGLA metabolized from GLA, so these results suggest that the dietary effect of DGLA would be more dominant than GLA.