New eudesmane sesquiterpenoids from Atractylodis Macrocephalae Rhizoma and their inhibitory activities against SREBPs / 中国中药杂志

Three sesquiterpenoids were isolated and purified from the 95% ethanol extract of Atractylodis Macrocephalae Rhizoma by column chromatography on silica gel, Sephadex LH-20, ODS, and high-performance liquid chromatography(HPLC). Their chemical structures were identified on the basis of spectroscopic analysis and physiochemical properties as(7Z)-8β,13-diacetoxy-eudesma-4(15),7(11)-diene(1), 7-oxo-7,8-secoeudesma-4(15),11-dien-8-oic acid(2), and guai-10(14)-en-11-ol(3). Compounds 1 and 2 are new compounds and compound 3 was obtained from Compositae family for the first time. Compounds 1, 2, and 3 showed weak inhibitory activities against sterol regulatory element-binding proteins(SREBPs).

The SREBP (Sterol Regulatory Element-Binding Protein) pathway: a regulatory bridge between carotenogenesis and sterol biosynthesis in the carotenogenic yeast Xanthophyllomyces dendrorhous

Xanthophyllomyces dendrorhous is a basidiomycete yeast that naturally produces the red-orange carotenoid astaxanthin, which has remarkable antioxidant properties. The biosynthesis of carotenoids and sterols share some common elements that have been studied in X. dendrorhous. For example, their synthesis requires metabolites derived from the mevalonate pathway and in both specific pathways, cytochrome P450 enzymes are involved that share a single cytochrome P450 reductase, CrtR, which is essential for astaxanthin biosynthesis, but is replaceable for ergosterol biosynthesis. Research on the regulation of carotenoid biosynthesis is still limited in X. dendrorhous; however, it is known that the Sterol Regulatory Element-Binding Protein (SREBP) pathway, which is a conserved regulatory pathway involved in the control of lipid metabolism, also regulates carotenoid production in X. dendrorhous. This review addresses the similarities and differences that have been observed between mammal and fungal SREBP pathways and what it is known about this pathway regarding the regulation of the production of carotenoids and sterols in X. dendrorhous.

Berberine mitigates nonalcoholic hepatic steatosis by downregulating SIRT1-FoxO1-SREBP2 pathway for cholesterol synthesis / 中西医结合学报

OBJECTIVE@#To investigate effects of berberine (BBR) on cholesterol synthesis in HepG2 cells with free fatty acid (FFA)-induced steatosis and to explore the underlying mechanisms.@*METHODS@#A steatosis cell model was induced in HepG2 cell line fed with FFA (0.5 mmol/L, oleic acid:palmitic acid = 2:1), and then treated with three concentrations of BBR; cell viability was assessed with cell counting kit-8 assays. Lipid accumulation in cells was observed through oil red O staining and total cholesterol (TC) content was detected by TC assay. The effects of BBR on cholesterol synthesis mediators were assessed by Western blotting and quantitative polymerase chain reaction. In addition, both silent information regulator 1 (SIRT1) and forkhead box transcription factor O1 (FoxO1) inhibitors were employed for validation.@*RESULTS@#FFA-induced steatosis was successfully established in HepG2 cells. Lipid accumulation and TC content in BBR groups were significantly lower (P < 0.05, P < 0.01), associated with significantly higher mRNA and protein levels of SIRT1(P < 0.05, P < 0.01), significantly lower sterol regulatory element-binding protein 2 (SREBP2) and 3-hydroxy 3-methylglutaryl-CoA reductase levels (P < 0.05, P < 0.01), as well as higher Acetyl-FoxO1 protein level (P < 0.05, P < 0.01) compared to the FFA only group. Both SIRT1 inhibitor SIRT1-IN-1 and FoxO1 inhibitor AS1842856 blocked the BBR-mediated therapeutic effects. Immunofluorescence showed that the increased SIRT1 expression increased FoxO1 deacetylation, and promoted its nuclear translocation.@*CONCLUSION@#BBR can mitigate FFA-induced steatosis in HepG2 cells by activating SIRT1-FoxO1-SREBP2 signal pathway. BBR may emerge as a potential drug candidate for treating nonalcoholic hepatic steatosis.

Moutan Cortex and Paeoniae Radix Rubra reverse high-fat-diet-induced metabolic disorder and restore gut microbiota homeostasis / 中国天然药物

The present study was designed to investigate the therapeutic effcts of Moutan Cortex (CM, root bark of Paeonia suffruticosa Andr) and Paeoniae Radix Rubra (PR, root of Paeonia veitchii Lynch) on metabolic disorders, focusing on the infuence of CM and PR on the obesity-related gut microbiota homeostasis. The diet-induced obese (DIO) mouse model was used to test the therapeutic effects of CM and PR. The mice were orally administered with CM and PR for 6 weeks, and oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were performed to evaluate the insulin sensitivity of the mice. Sterol-regulatory element binding proteins (SREBPs) and their target genes were measured by quantitative RT-PCR. High-throughput 16S ribosomal RNA (16S rRNA) gene sequencing technology was used to determine the composition of gut microbiota, and the metabolites in serum were analyzed by GC-MS. Our results indicated that CM and PR combination alleviated obese and insulin resistance in the DIO mice, leading to increased glucose uptake and gene expression in muscle and liver, and down-regulated SREBPs and their target genes in liver. Interesting, neither the CM-PR extracts, nor the major components of CM and PR did not affect SREBPs activity in cultured cells. Meanwhile, CM and PR significantly modulated the gut microbiota of the high-fat diet (HFD) treated mice, similar to metformin, and CM-PR reversed the overall microbiota composition similar to the normal chow diet (NCD) treated mice. In conclusion, our results provide novel mechanisms of action for the effects of CM and PR in treating DIO-induced dysregulation of sugar and lipid metabolism.

Efecto del extracto de maíz morado sobre la expresión génica de srebp-1, A5d y A6d en glándula mamaria de ratas nodrizas suplementadas con aceite de chía (Salvia Hispánica L) / Effect of purple corn extract on gene expression of srebp-1, A5d y A6d in mammary gland of nursing rats supplemented with chia oil (Salvia Hispánica L)

The effect of the dietary intake of purple-corn extract (EMM) as a source of anthocyanins and the oral supplementation of chia oil (CH), rich in α-linolenic acid on the lipid metabolism of the mammary glands were evaluated by gene expression SREBP-1, Δ6D Δ5D in 36 nursing rats distributed in olive oil (OL), chia oil (CH), olive oil - EMM (EMM OL +) or chia oil - EMM (CH + EMM) treatments. Gene expression of SREBP-1 was similar in OL and CH, increasing in presence of EMM; suggesting that under this conditions, CH and OL oils have similar effect on SREBP-1, while anthocyanins upregulate the gene expression. ALA inhibited the expression of desaturases, and the anthocyanins imaaproved Δ5D expression at control levels similar or higher in the case of Δ6D.

Se evaluó el efecto dietario de un extracto de maíz morado (EMM) como fuente de antocianinas y la suplementación oral de aceite de chía (CH), rico en ácido α-linolénico sobre la expresión génica de SREBP-1, Δ5D y Δ6D en en glándula mamaria de 36 ratas nodrizas distribuidas en cuatro tratamientos: aceites de oliva (OL), CH, OL + EMM o CH + EMM. La expresión de SREBP-1 fue similar en OL y CH, incrementándose en presencia de EMM. La expresión de Δ5D y Δ6D fue mayor en OL que en CH, donde incrementó en presencia de EMM, sugiriendo que bajo estas condiciones los aceites CH y OL tienen efectos similares sobre la expresión de SREBP-1 mientras las antocianinas regulan al alza dicha expresión. ALA inhibió la expresión de las desaturasas y la presencia de antocianinas aumentó la de Δ5D a niveles similares al control, o superiores en el caso de Δ6D.

Effects of chrysophanol on expression of SREBPs and lipid metabolism in Huh-7 cells / 药学学报

Rhubarb is a traditional Chinese medicines which possess laxative, lipid-lowering, and weight-loss activities, but the active compounds of lipid-lowering and underlying molecular mechanisms are not yet clear. This study aims to explore the effects of chrysophanol on the mRNA expressions of sterol regulatory element-binding proteins (SREBPs) and lipid metabolism in human liver carcinoma Huh-7 cells, which is one of the active compounds obtained from Rhubarb. A reporter gene assay was used to test the transcription of SREBP. The intracellular triglyceride and total cholesterol contents were measured by using commercially available test kits. The SREBPs target genes expressions were measured by Quantitative Real-Time PCR. Cell viability was evaluated by Cell Counting Kit-8. As the results shown, chrysophanol (40 μmol · L(-1), 16 h) could notably inhibited human SRE promoter activity in a dose-dependent manner and decrease intracellular cholesterol and triglyceride levels. Furthermore, the mRNA expressions of SREBPs target genes were significantly downregulated by chrysophanol treatment. However there are no significant differences on cell viability when compared with the control group. These results suggested that chrysophanol might improve lipid metabolism through suppressing the mRNA expressions of SREBPs target genes to attenuate intracellular lipid accumulation.

Lipid homeostasis and the formation of macrophage-derived foam cells in atherosclerosis

Atherosclerosis is a chronic, inflammatory disorder characterized by the deposition of excess lipids in the arterial intima. The formation of macrophage-derived foam cells in a plaque is a hallmark of the development of atherosclerosis. Lipid homeostasis, especially cholesterol homeostasis, plays a crucial role during the formation of foam cells. Recently, lipid droplet-associated proteins, including PAT and CIDE family proteins, have been shown to control the development of atherosclerosis by regulating the formation, growth, stabilization and functions of lipid droplets in macrophage-derived foam cells. This review focuses on the potential mechanisms of formation of macrophage-derived foam cells in atherosclerosis with particular emphasis on the role of lipid homeostasis and lipid droplet-associated proteins. Understanding the process of foam cell formation will aid in the future discovery of novel therapeutic interventions for atherosclerosis.

Activation of sterol regulatory element binding protein and its involvement in endothelial cell migration / 中华病理学杂志

<p><b>OBJECTIVE</b>To study the activation of sterol regulatory element binding protein (SREBP) and its critical role in endothelial cell migration.</p><p><b>METHODS</b>Bovine aortic endothelial cells (ECs) were cultured. The expression of SREBP and Cdc42 were determined by Western blot and quantitative real-time PCR. Moreover, outward growth migration model and transwell chamber assay were used to detect ECs migration.</p><p><b>RESULTS</b>(1) SREBP was activated during ECs migration. Western blot analysis demonstrated increased active form SREBP in migrating as compared to non-migrating ECs population. SREBP activation decreased as ECs migration slowed;(2) Coincidental with SREBP activation, mRNA expression of its target genes such as low density lipoprotein receptor, HMG-CoA reductase, and fatty acid synthase also increased in migrating ECs population as detected by real-time PCR; (3) Migration induced SREBP activation in ECs was inhibited by SREBP-acting protein RNAi and pharmacologically by 25-hydroxycholesterol; (4) Inhibition of SREBP led to decreased ECs migration in various models; (5) Cells genetically deficient in SREBP-acting protein, S1P, or S2P, phenotypically exhibited impaired migration; (6) SREBP inhibition in ECs suppressed the activity of small GTPase Cdc42, a key molecule for ECs motility.</p><p><b>CONCLUSIONS</b>SREBP is activated during and plays a critical role in ECs migration. Targeting SREBP could become a novel approach in fighting diseases involving abnormal ECs migration.</p>

The Effects of Genistein to Expression of Fatty Acid Synthase in Breast Cancer Cells / 한국유방암학회지

PURPOSE: The relatively low incidence of breast cancer in Asian countries with cultures which traditionally eat a large amount of soy is worth noticing in research fields. Genistein is a isoflavone phytoestrogen found in soy and its consumption may have a role in cancer etiology. We have established a hypothesis that a diet high in soy consumption is related to a low incidence of breast cancer. Fatty acid synthase (FAS) is a multi-protein enzyme responsible for de novo biosynthesis of fatty acids. Recent studies have demonstrated that high levels of FAS occurs in a subset of human cancers, such as breast cancer, ovarian cancer, and prostate cancer. High level of FAS are associated with a poor prognosis. Sterol regulatory element binding proteins (SREBPs) are a family of transcription factors that regulate genes involved in lipid metabolism, including FAS. Recent studies show that expression of SREBP1c is correlates with FAS expression. The aim of this study is to investigate the effect of genistein on the expression of FAS in breast cancer cells. METHODS: We performed immunofluorescent staining to examine the expression of FAS under different concentration of genistein. RT-PCR was also performed to investigate the mRNA expression of FAS and SREBP1c in different conditioned breast cancer cells treated with different concentration of FAS inhibitor and genistein. RESULTS: By immunofluorescent staining, the FAS expression after treatment with the FAS inhibitor, C75, decreased at a micron10 M concentration. However the expression of FAS decreased at all concentrations of genistein (0.5, 1, 5, 10 micronM). The mRNA levels of FAS and SREBP1c after treatment with C75 decreased constantly according to time and concentration. However the effect was noted only after 12 hr. The mRNA level of FAS and SREBP1c following treatment with genistein decreased at only a 10 micronM concentration (p<0.005). CONCLUSION: Genistein may down regulate FAS expression in breast cancer cells through modulation of SREBP-1c. This finding may account for the relatively low incidence of breast cancer in Asians who consume a large amount of soy in their diet.

Regulación del metabolismo del colesterol y ácidos grasos en el síndrome nefrótico experimental por las proteínas que se unen a los elementos regulatorios de esteroles (SREBP's): efecto de la soya / Metabolism of cholesterol and fatty acids in nephrotic syndrome and its regulation by sterol regulatory element brinding proteins (SREBP's): Effect of soy protein consumption

El síndrome nefrótico (SN) cursa con hiperlipidemia. Se conoce que la biosíntesis del colesterol y de los ácidos grasos es regulada por los factores transcripcionales que se unen a los elementos de respuesta a esteroles (SREBP's). El consumo de proteína de soya disminuye la concentración de estos lípidos, aunque su mecanismo de acción no es del todo conocido. El objetivo de este estudio fue conocer si el consumo de la proteína de soya reduce los niveles de colesterol y triglicéridos a través de una regulación de las SREBP 's. Se estudiaron ratas Wistar macho con SN experimental por 64 días. Se observó que las concentraciones plasmáticos de colesterol y triglicéridos plasmáticos, así como de la proteinuria eran significativamente menores en las ratas alimentadas con proteína de soya que aquellas que consumían caseína. Estos cambios se asociaron con disminución de la expresión del ARNm SREBP 1 y de las enzimas de la síntesis de ácidos grasos. Los análisis por Western Blot revelaron que en los núcleos de hepatocitos obtenidos de ratas alimentadas con proteína de soya hubo menor presencia del factor transcripcional SREBP 1. Los resultados de este estudio indican que el consumo de proteína de soya produce efectos benéficos durante el síndrome nefrótico.

Hyperlipidemia occurs during nephrotic syndrome (NS). It is known that cholesterol and fatty acid biosynthesis is controlled by the transcription factors sterol regulatory element binding proteins (SREBPs). Soy protein consumption reduces the concentration of these lipids, although its mechanism of action is not well known. The aim of the present study was to establish whether soy protein consumption reduces cholesterol and triglycerides levels by regulating of SREBPs. Male Wistar rats with experimental NS were studied for 64 days. The results showed that rats fed with soy protein had significantly lower plasma cholesterol and triglyceride concentrations as well as proteinuria than rats fed with casein diet. These decrements were associated with a decrease in the expression of SREBP 1 and fatty acid biosynthetic enzymes. In addition, Western blot analysis revealed that in nuclear extracts from hepatocytes of rats fed with soy protein, there was a lower concentration of SREBP 1 than in rats fed with casein. The results of this study indicate that consumption of a soy protein diet has beneficial effects on nephrotic syndrome.