RESUMEN
Sterol regulatory element-binding protein (SREBP) transcription factors are central regulators of lipid homeostasis and are essential for lipid metabolic reprogramming that supports tumor growth in multiple cancers. SREBP pathway inhibitors have been identified, but bioavailable compounds are lacking. To address this need, we designed a novel approach for screening a collection of 4,474 FDA-approved drugs. SREBPs are conditionally essential and required under low lipid conditions. Leveraging this property, we screened for drugs that inhibited pancreatic cancer cell growth in lipid-poor, but not lipid-rich, medium. The primary screen identified 83 drugs that inhibited cell growth in a lipid-dependent manner. Secondary assays examining SREBP target gene expression, SREBP proteolytic cleavage, and effects on human breast cancer cells identified 13 FDA-approved drugs that inhibit SREBP pathway activation. Taken together, we demonstrated that our screening approach can identify SREBP inhibitors from a small library of compounds. This high-throughput screening platform enables screening of large compound collections to discover novel small molecule SREBP inhibitors.
Asunto(s)
Ensayos Analíticos de Alto Rendimiento , Proteínas de Unión a los Elementos Reguladores de Esteroles , Humanos , Ensayos Analíticos de Alto Rendimiento/métodos , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismo , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Línea Celular Tumoral , Transducción de Señal/efectos de los fármacos , Estados Unidos , Bibliotecas de Moléculas Pequeñas/farmacología , Bibliotecas de Moléculas Pequeñas/química , Aprobación de Drogas , Proliferación Celular/efectos de los fármacos , United States Food and Drug Administration , Antineoplásicos/farmacologíaRESUMEN
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)-8ß,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).
Asunto(s)
Atractylodes , Medicamentos Herbarios Chinos , Sesquiterpenos de Eudesmano , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Atractylodes/química , Medicamentos Herbarios Chinos/química , Rizoma/química , Sesquiterpenos de Eudesmano/análisis , Sesquiterpenos de Eudesmano/farmacologíaRESUMEN
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).
Asunto(s)
Atractylodes/química , Medicamentos Herbarios Chinos/química , Rizoma/química , Sesquiterpenos de Eudesmano/farmacología , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidoresRESUMEN
AIMS: Potential anti-obesity effects of quinizarin, a plant anthraquinone, were investigated using 3 T3-L1 preadipocyte cells and high-fat diet (HD)-induced obese mice. MAIN METHOD: Cell viability was determined using the MTT assay. Triglyceride (TG) and lipid accumulation were determined using a TG assay kit and Oil Red O staining, respectively. Adipogenic, lipogenic, and lipolytic gene and protein expression was measured by RT-PCR or Western blot. Serum biochemical indices, including cholesterol and blood glucose, in HD-fed obese mice were determined using corresponding assay kits. Histological analysis was performed with haematoxylin and eosin (H&E) staining. RESULTS: Quinizarin (0-10 µM) significantly reduced intracellular TG and lipid droplets during the differentiation of preadipocytes. Quinizarin significantly suppressed the expression of adipocyte differentiation marker proteins, such as CCAAT/enhancer-binding protein ß (C/EBP-ß), C/EBP-α, PPAR-γ, and aP2, and lipogenic marker proteins, including SREBP1c, SREBP2, fatty acid synthase (FAS), and acetyl-CoA carboxylase 1 (ACC1), reduced ACC2 expression and increased carnitine palmitoyltransferase 1 (CPT1) expression. Oral administration of quinizarin (15-30 mg/kg/day) to HD-fed mice for 6 weeks reduced the body weight gain and size of liver adipocytes and epididymal fat tissues, with significant reductions in liver TG and serum total cholesterol, blood glucose, LDL, and HDL levels. SIGNIFICANCE: The results of this study indicated that quinizarin exerts anti-obesity effects by inhibiting both adipogenesis and lipogenesis and stimulating lipolysis in vitro and in vivo mainly by downregulating the SREBP signalling pathway; thus, it might be a potent candidate as a health-beneficial food or therapeutic agent to prevent or treat obesity.
Asunto(s)
Adipocitos/metabolismo , Antraquinonas/farmacología , Proteínas Potenciadoras de Unión a CCAAT/antagonistas & inhibidores , Diferenciación Celular/fisiología , Lipogénesis/fisiología , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Células 3T3-L1 , Adipocitos/efectos de los fármacos , Adipogénesis/efectos de los fármacos , Adipogénesis/fisiología , Animales , Proteínas Potenciadoras de Unión a CCAAT/metabolismo , Diferenciación Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/fisiología , Lipogénesis/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos C57BL , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismoRESUMEN
Vitamin D3 metabolites inhibit the expression of lipogenic genes by impairing sterol regulatory element-binding protein (SREBP), a master transcription factor of lipogenesis, independent of their canonical activity through a vitamin D receptor (VDR). Herein, we designed and synthesized a series of vitamin D derivatives to search for a drug-like small molecule that suppresses the SREBP-induced lipogenesis without affecting the VDR-controlled calcium homeostasis in vivo. Evaluation of the derivatives in cultured cells and mice led to the discovery of VDR-silent SREBP inhibitors and to the development of KK-052 (50), the first vitamin D-based SREBP inhibitor that has been demonstrated to mitigate hepatic lipid accumulation without calcemic action in mice. KK-052 maintained the ability of 25-hydroxyvitamin D3 to induce the degradation of SREBP but lacked in the VDR-mediated activity. KK-052 serves as a valuable compound for interrogating SREBP/SCAP in vivo and may represent an unprecedented translational opportunity of synthetic vitamin D analogues.
Asunto(s)
Diseño de Fármacos , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismo , Vitamina D/análogos & derivados , Animales , Peso Corporal/efectos de los fármacos , Células CHO , Cricetinae , Cricetulus , Reacción de Cicloadición , Modelos Animales de Enfermedad , Evaluación Preclínica de Medicamentos , Hígado Graso/tratamiento farmacológico , Humanos , Péptidos y Proteínas de Señalización Intracelular/antagonistas & inhibidores , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Lipogénesis/efectos de los fármacos , Proteínas de la Membrana/antagonistas & inhibidores , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Obesos , Receptores de Calcitriol/antagonistas & inhibidores , Receptores de Calcitriol/metabolismo , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Proteínas de Unión a los Elementos Reguladores de Esteroles/genética , Vitamina D/metabolismo , Vitamina D/farmacología , Vitamina D/uso terapéuticoRESUMEN
Regulatory T cells (Treg cells) are essential for immune tolerance1, but also drive immunosuppression in the tumour microenvironment2. Therapeutic targeting of Treg cells in cancer will therefore require the identification of context-specific mechanisms that affect their function. Here we show that inhibiting lipid synthesis and metabolic signalling that are dependent on sterol-regulatory-element-binding proteins (SREBPs) in Treg cells unleashes effective antitumour immune responses without autoimmune toxicity. We find that the activity of SREBPs is upregulated in intratumoral Treg cells. Moreover, deletion of SREBP-cleavage-activating protein (SCAP)-a factor required for SREBP activity-in these cells inhibits tumour growth and boosts immunotherapy that is triggered by targeting the immune-checkpoint protein PD-1. These effects of SCAP deletion are associated with uncontrolled production of interferon-γ and impaired function of intratumoral Treg cells. Mechanistically, signalling through SCAP and SREBPs coordinates cellular programs for lipid synthesis and inhibitory receptor signalling in these cells. First, de novo fatty-acid synthesis mediated by fatty-acid synthase (FASN) contributes to functional maturation of Treg cells, and loss of FASN from Treg cells inhibits tumour growth. Second, Treg cells in tumours show enhanced expression of the PD-1 gene, through a process that depends on SREBP activity and signals via mevalonate metabolism to protein geranylgeranylation. Blocking PD-1 or SREBP signalling results in dysregulated activation of phosphatidylinositol-3-kinase in intratumoral Treg cells. Our findings show that metabolic reprogramming enforces the functional specialization of Treg cells in tumours, pointing to new ways of targeting these cells for cancer therapy.
Asunto(s)
Metabolismo de los Lípidos , Neoplasias/inmunología , Neoplasias/metabolismo , Transducción de Señal , Linfocitos T Reguladores/citología , Linfocitos T Reguladores/inmunología , Animales , Colesterol/metabolismo , Ácido Graso Sintasas/metabolismo , Ácidos Grasos/metabolismo , Femenino , Regulación Neoplásica de la Expresión Génica , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Masculino , Proteínas de la Membrana/metabolismo , Ácido Mevalónico/metabolismo , Ratones , Fosfatidilinositol 3-Quinasa/metabolismo , Receptor de Muerte Celular Programada 1/antagonistas & inhibidores , Receptor de Muerte Celular Programada 1/metabolismo , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismo , Linfocitos T Reguladores/enzimología , Regulación hacia ArribaRESUMEN
Cancer is a multifaceted global disease. Transformation of a normal to a malignant cell takes several steps, including somatic mutations, epigenetic alterations, metabolic reprogramming and loss of cell growth control. Recently, the mevalonate pathway has emerged as a crucial regulator of tumor biology and a potential therapeutic target. This pathway controls cholesterol production and posttranslational modifications of Rho-GTPases, both of which are linked to several key steps of tumor progression. Inhibitors of the mevalonate pathway induce pleiotropic antitumor-effects in several human malignancies, identifying the pathway as an attractive candidate for novel therapies. In this review, we will provide an overview about the role and regulation of the mevalonate pathway in certain aspects of cancer initiation and progression and its potential for therapeutic intervention in oncology.
Asunto(s)
Antineoplásicos/farmacología , Transformación Celular Neoplásica/metabolismo , Colesterol/biosíntesis , Ácido Mevalónico/metabolismo , Neoplasias/metabolismo , Antineoplásicos/uso terapéutico , Proliferación Celular , Transformación Celular Neoplásica/efectos de los fármacos , Transformación Celular Neoplásica/patología , Ensayos Clínicos como Asunto , Progresión de la Enfermedad , Geraniltranstransferasa/antagonistas & inhibidores , Geraniltranstransferasa/metabolismo , Humanos , Hidroximetilglutaril-CoA Reductasas/metabolismo , Redes y Vías Metabólicas/efectos de los fármacos , Neoplasias/tratamiento farmacológico , Neoplasias/patología , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismo , Resultado del Tratamiento , Proteínas de Unión al GTP rho/metabolismoRESUMEN
HMG-CoA reductase (HMGCR) is the rate-limiting enzyme in the cholesterol biosynthetic pathway, and is the target of cholesterol-lowering drugs, statins. Previous studies have demonstrated that the enzyme activity is regulated by sterol-induced degradation in addition to transcriptional regulation through sterol-regulatory-element-binding proteins (SREBPs). While 25-hydroxycholesterol induces both HMGCR degradation and SREBP inhibition in a nonselective manner, lanosterol selectively induces HMGCR degradation. Here, to clarify the structural determinants of selectivity for the two activities, we established a luciferase-based assay monitoring HMGCR degradation and used it to profile the structure-activity/selectivity relationships of oxysterols and (oxy)lanosterols. We identified several sterols that selectively induce HMGCR degradation and one sterol, 25-hydroxycholest-4-en-3-one, that selectively inhibits the SREBP pathway. These results should be helpful in designing more potent and selective HMGCR degraders.
Asunto(s)
Hidroximetilglutaril-CoA Reductasas/metabolismo , Lanosterol/metabolismo , Oxiesteroles/metabolismo , Células HEK293 , Humanos , Lanosterol/farmacología , Estructura Molecular , Oxiesteroles/farmacología , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismo , Relación Estructura-ActividadRESUMEN
Background Trypanosoma cruzi is an intracellular parasite that causes debilitating chronic Chagas cardiomyopathy (CCM), for which there is no effective drug or vaccine. Previously, we demonstrated increased cardiac lipid accumulation and endoplasmic reticulum stress in mice with CCM. Increased endoplasmic reticulum stress may lead to uncontrolled SREBP (sterol regulatory element-binding protein) activation and lipotoxicity in the myocardium during the intermediate stage of infection and result in progression to chronic CCM. Therefore, we investigated whether inhibiting SREBP activation modulates CCM progression in T cruzi-infected mice. Methods and Results T cruzi-infected cultured cardiomyocytes (3:1 multiplicity of infection; 24 hours postinfection) were incubated with betulin (3 µmol/L per mL), an SREBP inhibitor, for 24 hours. Quantitative polymerase chain reaction and Western blotting analyses demonstrated a significant reduction in SREBP activation, lipid biosynthesis, and endoplasmic reticulum stress in betulin-treated infected cells compared with untreated cells. T cruzi infected (103 trypomastigotes of the Brazil strain) Swiss mice were fed a customized diet containing betulin during the intermediate stage (40 days postinfection) until the chronic stage (120 DPI). Cardiac ultrasound imaging and histological and biochemical analyses demonstrated anatomical and functional improvements in betulin-treated, infected mice compared with untreated controls: we observed a significant reduction in cholesterol/fatty acid synthesis that may result in the observed cardiac reduction in cardiac lipid accumulation, mitochondrial and endoplasmic reticulum stress, and ventricular enlargement. Conclusions Our study (in vitro and vivo) demonstrates that inhibition of cardiac SREBP activation reduces cardiac damage during T cruzi infection and modulates CCM in a murine Chagas model.
Asunto(s)
Cardiomiopatía Chagásica/tratamiento farmacológico , Estrés del Retículo Endoplásmico/efectos de los fármacos , Metabolismo de los Lípidos/efectos de los fármacos , Miocitos Cardíacos/efectos de los fármacos , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Triterpenos/farmacología , Trypanosoma cruzi/patogenicidad , Animales , Línea Celular , Cardiomiopatía Chagásica/metabolismo , Cardiomiopatía Chagásica/parasitología , Cardiomiopatía Chagásica/patología , Enfermedad Crónica , Modelos Animales de Enfermedad , Interacciones Huésped-Parásitos , Masculino , Ratones Endogámicos C3H , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/parasitología , Miocitos Cardíacos/patología , Ratas , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismoRESUMEN
Vitamin D3 metabolites are capable of controlling gene expression in mammalian cells through two independent pathways: vitamin D receptor (VDR) and sterol regulatory element-binding protein (SREBP) pathways. In the present study, we dissect the complex biological activity of vitamin D by designing synthetic vitamin D3 analogs specific for VDR or SREBP pathway, i.e., a VDR activator that lacks SREBP inhibitory activity, or an SREBP inhibitor devoid of VDR activity. These synthetic vitamin D probes permitted identification of one of the vitamin D-responsive genes, Soat1, as an SREBP-suppressed gene. The chemical probes developed in the present study may prove useful in dissecting the intricate interplay of vitamin D actions, thereby providing insights into how vitamin D target genes are regulated.
Asunto(s)
Sondas Moleculares/química , Vitamina D/farmacología , Descubrimiento de Drogas , Humanos , Receptores de Calcitriol/metabolismo , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismo , Vitamina D/metabolismoRESUMEN
Covalent conjugates of multiple nutrients often exhibit greater biological activities than each individual nutrient and more predictable safety profiles than completely unnatural chemical entities. Here, we report the construction and application of a focused chemical library of 308 covalent conjugates of a variety of small-molecule nutrients. Screening of the library with a reporter gene of sterol regulatory element-binding protein (SREBP), a master regulator of mammalian lipogenesis, led to the discovery of a conjugate of docosahexaenoic acid (DHA), glucosamine, and amino acids as an inhibitor of SREBP (molecule 1, DHG). Mechanistic analyses indicate that molecule 1 impairs the SREBP activity by inhibiting glucose transporters and thereby activating AMP-activated protein kinase (AMPK). Oral administration of molecule 1 suppressed the intestinal absorption of glucose in mice. These results suggest that such synthetic libraries of nutrient conjugates serve as a source of novel chemical tools and pharmaceutical seeds that modulate energy metabolism.
Asunto(s)
Nutrientes/farmacología , Bibliotecas de Moléculas Pequeñas/farmacología , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Aminoácidos/síntesis química , Aminoácidos/farmacología , Animales , Células CACO-2 , Ácidos Grasos Insaturados/síntesis química , Ácidos Grasos Insaturados/farmacología , Genes Reporteros , Glucosamina/síntesis química , Glucosamina/farmacología , Glucosa/metabolismo , Humanos , Absorción Intestinal/efectos de los fármacos , Masculino , Ratones Endogámicos ICR , Nutrientes/síntesis química , Bibliotecas de Moléculas Pequeñas/síntesis química , Proteínas de Unión a los Elementos Reguladores de Esteroles/genética , Vitaminas/síntesis química , Vitaminas/farmacologíaRESUMEN
Sterol regulatory element-binding proteins (SREBPs) are transcription factors that regulate the expression of genes involved in fatty acid and cholesterol biosynthetic pathways. The present study showed that the flavonoid chrysin impairs the fatty acid synthase promoter. Chrysin reduces the expression of SREBP target genes, such as fatty acid synthase, in human hepatoma Huh-7 cells and impairs de novo synthesis of fatty acids and cholesterol. Moreover, it reduces the endogenous mature, transcriptionally active forms of SREBPs, which are generated by the proteolytic processing of precursor forms. In addition, chrysin reduces the enforced expressing mature forms of SREBPs and their transcriptional activity. The ubiquitin-proteasome system is not involved in the chrysin-mediated reduction of SREBPs mature forms. These results suggest that chrysin suppresses SREBP activity, at least partially, via the degradation of SREBPs mature forms. Abbreviations: ACC1: acetyl-CoA carboxylase 1; DMEM: Dulbecco's modified Eagle's medium; FAS: fatty acid synthase; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; 25-HC: 25-hydroxycholesterol; HMGCS: HMG-CoA synthase; LDH: lactate dehydrogenase; LPDS: lipoprotein-deficient serum; PI3K: phosphatidylinositol 3-kinase; SCD1: stearoyl-CoA desaturase; SREBPs: sterol regulatory element-binding proteins.
Asunto(s)
Flavonoides/farmacología , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismo , Animales , Línea Celular Tumoral , Colesterol/biosíntesis , Ácido Graso Sintasas/genética , Ácidos Grasos/biosíntesis , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Regiones Promotoras Genéticas , Proteolisis , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Proteínas de Unión a los Elementos Reguladores de Esteroles/genéticaRESUMEN
Nonalcoholic steatohepatitis (NASH) is a rapidly growing cause of chronic liver damage, cirrhosis, and hepatocellular carcinoma. How fatty liver pathogenesis is subject to epigenetic regulation is unknown. We hypothesized that chromatin remodeling is important for the pathogenesis of fatty liver disease. AT-rich interactive domain-containing protein 1A (ARID1A), a DNA-binding component of the SWItch/sucrose nonfermentable adenosine triphosphate-dependent chromatin-remodeling complex, contributes to nucleosome repositioning and access by transcriptional regulators. Liver-specific deletion of Arid1a (Arid1a liver knockout [LKO]) caused the development of age-dependent fatty liver disease in mice. Transcriptome analysis revealed up-regulation of lipogenesis and down-regulation of fatty acid oxidation genes. As evidence of direct regulation, ARID1A demonstrated direct binding to the promoters of many of these differentially regulated genes. Additionally, Arid1a LKO mice were more susceptible to high-fat diet-induced liver steatosis and fibrosis. We deleted Pten in combination with Arid1a to synergistically drive fatty liver progression. Inhibition of lipogenesis using CAT-2003, a potent sterol regulatory element-binding protein inhibitor, mediated improvements in markers of fatty liver disease progression in this Arid1a/Pten double knockout model. Conclusion: ARID1A plays a role in the epigenetic regulation of hepatic lipid homeostasis, and its suppression contributes to fatty liver pathogenesis. Combined Arid1a and Pten deletion shows accelerated fatty liver disease progression and is a useful mouse model for studying therapeutic strategies for NASH.
Asunto(s)
Proteínas de Unión al ADN/deficiencia , Lipogénesis , Hígado/metabolismo , Enfermedad del Hígado Graso no Alcohólico/etiología , Factores de Transcripción/deficiencia , Animales , Proteínas de Unión al ADN/antagonistas & inhibidores , Proteínas de Unión al ADN/genética , Ácidos Grasos/metabolismo , Ratones , Ratones Noqueados , Terapia Molecular Dirigida , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Oxidación-Reducción , Fosfohidrolasa PTEN/deficiencia , Fosfohidrolasa PTEN/genética , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Factores de Transcripción/antagonistas & inhibidores , Factores de Transcripción/genéticaRESUMEN
Fatostatin, a chemical inhibitor of the sterol regulatory elementbinding protein (SREBP) pathway, has been reported to possess high antitumor activity against prostate and pancreatic cancer. The main aim of the present study was to investigate the effects and mechanism of fatostatin in endometrial carcinoma (EC). In the present study, we determined that fatostatin inhibited EC cell viability and colony formation capacity, decreased the invasive and migratory capacities of EC cells, induced EC cell cycle arrest at the G2/M phase and stimulated caspasemediated apoptosis of EC cells. In addition, fatostatin significantly decreased the protein expression levels of nuclear SREBPs and their downstream genes and increased the protein expression levels of cleaved caspase9, caspase3 and PARP in EC cells. In addition, the mRNA expression levels of SREBPcontrolled downstream genes were also significantly downregulated. The quantification assays of fatty acids and total cholesterol revealed that the levels of free fatty acids and total cholesterol in EC cells were decreased. The present study indicated that fatostatin exhibited antitumor effects by blocking SREBPregulated metabolic pathways and inducing caspasemediated apoptosis in EC and may be a potent therapeutic strategy for the treatment of EC.
Asunto(s)
Proliferación Celular/efectos de los fármacos , Neoplasias Endometriales/tratamiento farmacológico , Piridinas/administración & dosificación , Proteínas de Unión a los Elementos Reguladores de Esteroles/genética , Tiazoles/administración & dosificación , Apoptosis/efectos de los fármacos , Caspasas/genética , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Neoplasias Endometriales/genética , Neoplasias Endometriales/patología , Femenino , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Redes y Vías Metabólicas/efectos de los fármacos , Células Madre/efectos de los fármacos , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidoresRESUMEN
There is increased expression of liver x receptor (LXR) target genes and reduced low density lipoprotein receptor (LDLR) during spontaneous luteolysis in primates. The LXRs are nuclear receptors that increase cholesterol efflux by inducing transcription of their target genes. Transcription of LDLR is regulated by sterol regulatory element binding proteins (SREBPs). Human chorionic gonadotropin (hCG) prevents luteolysis and stimulates progesterone synthesis via protein kinase A (PKA). Thus, our primary objectives are: 1) Determine the effects of LXR activation and SREBP inhibition on progesterone secretion and cholesterol metabolism, and 2) Determine whether hCG signaling via PKA regulates transcription of LXR and SREBP target genes in human luteinized granulosa cells. Basal and hCG-stimulated progesterone secretion was significantly decreased by the combined actions of the LXR agonist T0901317 and the SREBP inhibitor fatostatin, which was associated with reduced intracellular cholesterol storage. Expression of LXR target genes in the presence of T0901317 was significantly reduced by hCG, while hCG promoted transcriptional changes that favor LDL uptake. These effects of hCG were reversed by a specific PKA inhibitor. A third objective was to resolve a dilemma concerning LXR regulation of steroidogenic acute regulatory protein (STAR) expression in primate and non-primate steroidogenic cells. T0901317 induced STAR expression and progesterone synthesis in ovine, but not human cells, revealing a key difference between species in LXR regulation of luteal function. Collectively, these data support the hypothesis that LXR-induced cholesterol efflux and reduced LDL uptake via SREBP inhibition mediates luteolysis in primates, which is prevented by hCG.
Asunto(s)
Gonadotropina Coriónica/farmacología , Receptores X del Hígado/metabolismo , Células Lúteas/metabolismo , Progesterona/metabolismo , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismo , Animales , Colesterol/metabolismo , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Hidrocarburos Fluorados/farmacología , Receptores X del Hígado/antagonistas & inhibidores , Receptores X del Hígado/genética , Células Lúteas/efectos de los fármacos , Modelos Biológicos , Fosfoproteínas/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Piridinas/farmacología , Receptores de LDL/metabolismo , Ovinos , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Proteínas de Unión a los Elementos Reguladores de Esteroles/genética , Sulfonamidas/farmacología , Tiazoles/farmacología , Transcripción Genética/efectos de los fármacosRESUMEN
Nowadays, more and more attention has been paid to osteoporosis caused by diabetes mellitus. Elevated levels of pro-inflammatory cytokines in diabetic patients activate the activity of osteoclasts through the RANKL/OPG pathway. The nuclear transcription factor SREBP2, a master regulator of cholesterol metabolism, has been found involved in osteoclastogenesis. In our previous study, we have identified anhydroicaritin as a potent inhibitor of transcription factor SREBPs, which improves dyslipidemia and insulin resistance. In this study, we demonstrated that anhydroicaritin could also decrease the level of SREBP2 and its target genes in osteoclasts induced by RANKL without significant cytotoxicity. Moreover, anhydroicaritin suppressed RANKL-induced osteoclasts differentiation. In STZ-induced diabetic mice model, we found that the osteoclasts were largely increased accompanied with deterioration of bone structure. Anhydroicaritin decreased the level of blood glucose and alleviated insulin resistance. More importantly, anhydroicaritin inhibited osteoclast differentiation and rescued diabetes-induced bone loss in vivo. In conclusion, anhydroicaritin, a potent SREBP2 inhibitor, inhibits the osteoclasts formation and improves diabetes-induced bone loss.
Asunto(s)
Benzopiranos/farmacología , Diferenciación Celular/efectos de los fármacos , Diabetes Mellitus Experimental/complicaciones , Osteoclastos/efectos de los fármacos , Osteoporosis/patología , Ligando RANK/farmacología , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Animales , Benzopiranos/uso terapéutico , Línea Celular , Ratones , Osteoclastos/citología , Osteoclastos/patología , Osteoporosis/complicaciones , Osteoporosis/tratamiento farmacológico , Transducción de Señal/efectos de los fármacosRESUMEN
Flaviviruses are positive-strand RNA viruses distributed all over the world that infect millions of people every year and for which no specific antiviral agents have been approved. These viruses include the mosquito-borne West Nile virus (WNV), which is responsible for outbreaks of meningitis and encephalitis. Considering that nordihydroguaiaretic acid (NDGA) has been previously shown to inhibit the multiplication of the related dengue virus and hepatitis C virus, we have evaluated the effect of NDGA, and its methylated derivative tetra-O-methyl nordihydroguaiaretic acid (M4N), on the infection of WNV. Both compounds inhibited the infection of WNV, likely by impairing viral replication. Since flavivirus multiplication is highly dependent on host cell lipid metabolism, the antiviral effect of NDGA has been previously related to its ability to disturb the lipid metabolism, probably by interfering with the sterol regulatory element-binding proteins (SREBP) pathway. Remarkably, we observed that other structurally unrelated inhibitors of the SREBP pathway, such as PF-429242 and fatostatin, also reduced WNV multiplication, supporting that the SREBP pathway may constitute a druggable target suitable for antiviral intervention against flavivirus infection. Moreover, treatment with NDGA, M4N, PF-429242, and fatostatin also inhibited the multiplication of the mosquito-borne flavivirus Zika virus (ZIKV), which has been recently associated with birth defects (microcephaly) and neurological disorders. Our results point to SREBP inhibitors, such as NDGA and M4N, as potential candidates for further antiviral development against medically relevant flaviviruses.
Asunto(s)
Antivirales/farmacología , Masoprocol/análogos & derivados , Masoprocol/farmacología , Fiebre del Nilo Occidental/tratamiento farmacológico , Virus del Nilo Occidental/crecimiento & desarrollo , Infección por el Virus Zika/tratamiento farmacológico , Virus Zika/crecimiento & desarrollo , Animales , Línea Celular , Chlorocebus aethiops , Células HeLa , Humanos , Metabolismo de los Lípidos/efectos de los fármacos , Piridinas/farmacología , Pirrolidinas/farmacología , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Tiazoles/farmacología , Células Vero , Replicación Viral/efectos de los fármacos , Virus del Nilo Occidental/efectos de los fármacos , Virus Zika/efectos de los fármacosRESUMEN
The therapeutic use of statins has been associated to a reduced risk of Parkinson's disease (PD) and may hold neuroprotective potential by counteracting the degeneration of dopaminergic neurons. Transcriptional activation of the sterol regulatory element-binding protein (SREBP) is one of the major downstream signaling pathways triggered by the cholesterol-lowering effect of statins. In a previous study in neuroblastoma cells, we have shown that statins consistently induce the upregulation of presynaptic dopaminergic proteins and changes of their function and these effects were accompanied by downstream activation of SREBP. In this study, we aimed to determine the direct role of SREBP pathway in the modulation of dopaminergic phenotype. We demonstrate that treatment of SH-SY5Y cells with U18666A, an SREBP activator, increases the translocation of SREBPs into the nucleus, increases the expression of SREBP-1, SREBP-2, and of the presynaptic dopaminergic markers such as vesicular monoamine transporter 2, synaptic vesicle glycoprotein 2 A and 2 C, synaptogyrin-3, and tyrosine hydroxylase. The addition of SREBP inhibitor, PF-429242, blocks the increase of U18666A-induced expression of SREBPs and presynaptic markers. Our results, in line with previously reported effects of statins, demonstrate that direct stimulation of SREBP translocation is associated to differentiation toward a dopaminergic-like phenotype and suggest that SREBP-mediated transcriptional activity may lead to the restoration of the presynaptic dopamine markers and may contribute to neuroprotection of dopaminergic neurons. These findings further support the potential protective role of statin in PD and shed light upon SREBP as a potential new target for developing disease-modifying treatment in PD.
Asunto(s)
Androstenos/farmacología , Dopaminérgicos/farmacología , Neuronas Dopaminérgicas/efectos de los fármacos , Terminales Presinápticos/efectos de los fármacos , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismo , Transporte Activo de Núcleo Celular/efectos de los fármacos , Anticolesterolemiantes/farmacología , Línea Celular Tumoral , Núcleo Celular/efectos de los fármacos , Núcleo Celular/metabolismo , Neuronas Dopaminérgicas/citología , Neuronas Dopaminérgicas/fisiología , Expresión Génica/efectos de los fármacos , Humanos , Glicoproteínas de Membrana/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Terminales Presinápticos/fisiología , Pirrolidinas/farmacología , ARN Mensajero/metabolismo , Transducción de Señal/efectos de los fármacos , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Sinaptogirinas/metabolismo , Proteínas de Transporte Vesicular de Monoaminas/metabolismoRESUMEN
Cholesterol is important for normal brain function. The brain synthesizes its own cholesterol, presumably in astrocytes. We have previously shown that diabetes results in decreased brain cholesterol synthesis by a reduction in sterol regulatory element-binding protein 2 (SREBP2)-regulated transcription. Here we show that coculture of control astrocytes with neurons enhances neurite outgrowth, and this is reduced with SREBP2 knockdown astrocytes. In vivo, mice with knockout of SREBP2 in astrocytes have impaired brain development and behavioral and motor defects. These mice also have altered energy balance, altered body composition, and a shift in metabolism toward carbohydrate oxidation driven by increased glucose oxidation by the brain. Thus, SREBP2-mediated cholesterol synthesis in astrocytes plays an important role in brain and neuronal development and function, and altered brain cholesterol synthesis may contribute to the interaction between metabolic diseases, such as diabetes and altered brain function.
Asunto(s)
Astrocitos/metabolismo , Composición Corporal/fisiología , Encéfalo/metabolismo , Colesterol/metabolismo , Metabolismo Energético/fisiología , Proteína 2 de Unión a Elementos Reguladores de Esteroles/deficiencia , Animales , Composición Corporal/genética , Línea Celular Tumoral , Metabolismo Energético/genética , Femenino , Técnicas de Silenciamiento del Gen , Glioma/patología , Glucosa/metabolismo , Hiperinsulinismo/metabolismo , Masculino , Aprendizaje por Laberinto , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/genética , Comportamiento de Nidificación , Neuritas/ultraestructura , Oxidación-Reducción , Ratas , Prueba de Desempeño de Rotación con Aceleración Constante , Proteína 2 de Unión a Elementos Reguladores de Esteroles/genética , Proteína 2 de Unión a Elementos Reguladores de Esteroles/fisiología , Proteínas de Unión a los Elementos Reguladores de Esteroles/antagonistas & inhibidores , Proteínas de Unión a los Elementos Reguladores de Esteroles/genéticaRESUMEN
Sterol regulatory element-binding proteins (SREBPs) are transcription factors that control lipid homeostasis. SREBP activation is regulated by a negative feedback loop in which sterols bind to SREBP cleavage-activating protein (SCAP), an escort protein essential for SREBP activation, or to insulin-induced genes (Insigs) (endoplasmic reticulum [ER] anchor proteins), sequestering the SREBP-SCAP-Insig complex in the ER. We screened a chemical library of endogenous molecules and identified 25-hydroxyvitamin D (25OHD) as an inhibitor of SREBP activation. Unlike sterols and other SREBP inhibitors, 25OHD impairs SREBP activation by inducing proteolytic processing and ubiquitin-mediated degradation of SCAP, thereby decreasing SREBP levels independently of the vitamin D receptor. Vitamin D supplementation has been proposed to reduce the risk of metabolic diseases, but the mechanisms are unknown. The present results suggest a previously unrecognized molecular mechanism of vitamin D-mediated lipid control that might be useful in the treatment of metabolic diseases.