RESUMO
A known (1) and a structurally related new natural product (2), both belonging to the amorfrutin benzoic acid class, were isolated from the roots of Glycyrrhiza foetida. Compound 1 (amorfrutin B) is an efficient agonist of the nuclear peroxisome proliferator activated receptor (PPAR) gamma and of other PPAR subtypes. Compound 2 (amorfrutin C) showed comparably lower PPAR activation potential. Amorfrutin C exhibited striking antiproliferative effects for human colorectal cancer cells (HT-29 and T84), prostate cancer (PC-3), and breast cancer (MCF7) cells (IC50 values ranging from 8 to 16 µM in these cancer cell lines). Notably, amorfrutin C (2) showed less potent antiproliferative effects in primary colon cells. For HT-29 cells, compound 2 induced G0/G1 cell cycle arrest and modulated protein expression of key cell cycle modulators. Amorfrutin C further induced apoptotic events in HT-29 cells, including caspase activation, DNA fragmentation, PARP cleavage, phosphatidylserine externalization, and formation of reactive oxygen species. Mechanistic studies revealed that 2 disrupts the mitochondrial integrity by depolarization of the mitochondrial membrane (IC50 0.6 µM) and permanent opening of the mitochondrial permeability transition pore, leading to increased mitochondrial oxygen consumption and extracellular acidification. Structure-activity-relationship experiments revealed the carboxylic acid and the hydroxy group residues of 2 as fundamental structural requirements for inducing these apoptotic effects. Synergy analyses demonstrated stimulation of the death receptor signaling pathway. Taken together, amorfrutin C (2) represents a promising lead for the development of anticancer drugs.
Assuntos
Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Glycyrrhiza/química , Mitocôndrias/metabolismo , Salicilatos/isolamento & purificação , Salicilatos/farmacologia , Antineoplásicos Fitogênicos/química , Caspases/metabolismo , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Neoplasias do Colo/metabolismo , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Células HT29 , Humanos , Concentração Inibidora 50 , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Estrutura Molecular , Marrocos , Receptores Ativados por Proliferador de Peroxissomo/agonistas , Raízes de Plantas/química , Espécies Reativas de Oxigênio/metabolismo , Salicilatos/química , Relação Estrutura-Atividade , Proteína X Associada a bcl-2/metabolismoRESUMO
UNLABELLED: We introduce PHOXTRACK (PHOsphosite-X-TRacing Analysis of Causal Kinases), a user-friendly freely available software tool for analyzing large datasets of post-translational modifications of proteins, such as phosphorylation, which are commonly gained by mass spectrometry detection. In contrast to other currently applied data analysis approaches, PHOXTRACK uses full sets of quantitative proteomics data and applies non-parametric statistics to calculate whether defined kinase-specific sets of phosphosite sequences indicate statistically significant concordant differences between various biological conditions. PHOXTRACK is an efficient tool for extracting post-translational information of comprehensive proteomics datasets to decipher key regulatory proteins and to infer biologically relevant molecular pathways. AVAILABILITY: PHOXTRACK will be maintained over the next years and is freely available as an online tool for non-commercial use at http://phoxtrack.molgen.mpg.de. Users will also find a tutorial at this Web site and can additionally give feedback at https://groups.google.com/d/forum/phoxtrack-discuss.
Assuntos
Processamento de Proteína Pós-Traducional , Software , Animais , Humanos , Espectrometria de Massas , Fosforilação , Proteínas/química , Proteômica/métodosRESUMO
Gaining understanding of common complex diseases and their treatments are the main drivers for life sciences. As we show here, comprehensive protein set analyses offer new opportunities to decipher functional molecular networks of diseases and assess the efficacy and side-effects of treatments in vivo. Using mass spectrometry, we quantitatively detected several thousands of proteins and observed significant changes in protein pathways that were (dys-) regulated in diet-induced obesity mice. Analysis of the expression and post-translational modifications of proteins in various peripheral metabolic target tissues including adipose, heart, and liver tissue generated functional insights in the regulation of cell and tissue homeostasis during high-fat diet feeding and medication with two antidiabetic compounds. Protein set analyses singled out pathways for functional characterization, and indicated, for example, early-on potential cardiovascular complication of the diabetes drug rosiglitazone. In vivo protein set detection can provide new avenues for monitoring complex disease processes, and for evaluating preclinical drug candidates.
Assuntos
Hipoglicemiantes/farmacologia , Obesidade/metabolismo , Tiazolidinedionas/farmacologia , Tecido Adiposo Branco/metabolismo , Animais , Dieta Hiperlipídica , Hipoglicemiantes/uso terapêutico , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Miocárdio/metabolismo , Obesidade/tratamento farmacológico , PPAR gama/agonistas , Processamento de Proteína Pós-Traducional , Proteômica , Rosiglitazona , Salicilatos/farmacologia , Tiazolidinedionas/uso terapêuticoRESUMO
Given worldwide increases in the incidence of obesity and type 2 diabetes, new strategies for preventing and treating metabolic diseases are needed. The nuclear receptor PPARγ (peroxisome proliferator-activated receptor gamma) plays a central role in lipid and glucose metabolism; however, current PPARγ-targeting drugs are characterized by undesirable side effects. Natural products from edible biomaterial provide a structurally diverse resource to alleviate complex disorders via tailored nutritional intervention. We identified a family of natural products, the amorfrutins, from edible parts of two legumes, Glycyrrhiza foetida and Amorpha fruticosa, as structurally new and powerful antidiabetics with unprecedented effects for a dietary molecule. Amorfrutins bind to and activate PPARγ, which results in selective gene expression and physiological profiles markedly different from activation by current synthetic PPARγ drugs. In diet-induced obese and db/db mice, amorfrutin treatment strongly improves insulin resistance and other metabolic and inflammatory parameters without concomitant increase of fat storage or other unwanted side effects such as hepatoxicity. These results show that selective PPARγ-activation by diet-derived ligands may constitute a promising approach to combat metabolic disease.
Assuntos
Produtos Biológicos/farmacologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Fabaceae/química , Hipoglicemiantes/farmacologia , Salicilatos/farmacologia , Células 3T3-L1 , Animais , Produtos Biológicos/química , Produtos Biológicos/metabolismo , Western Blotting , Células CHO , Cricetinae , Cricetulus , Cristalografia por Raios X , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/etiologia , Dieta Hiperlipídica/efeitos adversos , Suplementos Nutricionais , Expressão Gênica/efeitos dos fármacos , Glycyrrhiza/química , Humanos , Hipoglicemiantes/química , Hipoglicemiantes/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Estrutura Molecular , Obesidade/complicações , Obesidade/tratamento farmacológico , Obesidade/etiologia , PPAR gama/genética , PPAR gama/metabolismo , Ligação Proteica , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Salicilatos/química , Salicilatos/metabolismoRESUMO
The incidences of obesity and type 2 diabetes are rapidly increasing and have evolved into a global epidemic. In this study, we analyzed the molecular effects of high-fat diet (HFD)-induced insulin-resistance on mice in two metabolic target tissues, the white adipose tissue (WAT) and the liver. Additionally, we analyzed the effects of drug treatment using the specific PPARγ ligand rosiglitazone. We integrated transcriptome, proteome, and metabolome data sets for a combined holistic view of molecular mechanisms in type 2 diabetes. Using network and pathway analyses, we identified hub proteins such as SDHB and SUCLG1 in WAT and deregulation of major metabolic pathways in the insulin-resistant state, including the TCA cycle, oxidative phosphorylation, and branched chain amino acid metabolism. Rosiglitazone treatment resulted mainly in modulation via PPAR signaling and oxidative phosphorylation in WAT only. Interestingly, in HFD liver, we could observe a decrease of proteins involved in vitamin B metabolism such as PDXDC1 and DHFR and the according metabolites. Furthermore, we could identify sphingosine (Sph) and sphingosine 1-phosphate (SP1) as a drug-specific marker pair in the liver. In summary, our data indicate physiological plasticity gained by interconnected molecular pathways to counteract metabolic dysregulation due to high calorie intake and drug treatment.
Assuntos
Tecido Adiposo Branco/metabolismo , Dieta Hiperlipídica/efeitos adversos , Hipoglicemiantes/farmacologia , Resistência à Insulina , Fígado/metabolismo , Tiazolidinedionas/farmacologia , Animais , Diabetes Mellitus Tipo 2/etiologia , Diabetes Mellitus Tipo 2/metabolismo , Perfilação da Expressão Gênica , Hipoglicemiantes/uso terapêutico , Masculino , Redes e Vias Metabólicas , Metabolômica , Camundongos Endogâmicos C57BL , Obesidade/etiologia , Obesidade/metabolismo , Proteômica , Rosiglitazona , Espectrometria de Massas em Tandem , Tiazolidinedionas/uso terapêutico , TranscriptomaRESUMO
Cellular communication is a fundamental process in biology. The interaction of adipocytes with macrophages is a key event in the development of common diseases such as type 2 diabetes. We applied an established bilayer cell co-culture system and comprehensive mass spectrometry analysis to detect proteome-wide the paracrine interaction of murine adipocytes and macrophages. Altogether, we identified 4486 proteins with at least two unique peptides of which 2392 proteins were informative for 3T3-L1 adipocytes and 2957 proteins for RAW 264.7 macrophages. Further, we observed over 12,000 phosphorylation sites of which we could assign 3,200 informative phosphopeptides with a single phosphosite for adipocytes and 4,514 for macrophages. Using protein set enrichment and phosphosite analyses, we deciphered regulatory protein pathways involved in cellular stress and inflammation, which can contribute to metabolic impairment of cells including insulin resistance and other disorders. The generated data sets provide a holistic, molecular pathway-centric view on the interplay of adipocytes and macrophages in disease processes and a resource for further studies.
Assuntos
Adipócitos/metabolismo , Comunicação Celular , Macrófagos/metabolismo , Proteoma/metabolismo , Animais , Linhagem Celular , Técnicas de Cocultura , Camundongos , Fosfopeptídeos/metabolismo , Fosforilação , Transdução de Sinais , TranscriptomaRESUMO
Recent studies that compared transcriptomic datasets of human diseases with datasets from mouse models using traditional gene-to-gene comparison techniques resulted in contradictory conclusions regarding the relevance of animal models for translational research. A major reason for the discrepancies between different gene expression analyses is the arbitrary filtering of differentially expressed genes. Furthermore, the comparison of single genes between different species and platforms often is limited by technical variance, leading to misinterpretation of the con/discordance between data from human and animal models. Thus, standardized approaches for systematic data analysis are needed. To overcome subjective gene filtering and ineffective gene-to-gene comparisons, we recently demonstrated that gene set enrichment analysis (GSEA) has the potential to avoid these problems. Therefore, we developed a standardized protocol for the use of GSEA to distinguish between appropriate and inappropriate animal models for translational research. This protocol is not suitable to predict how to design new model systems a-priori, as it requires existing experimental omics data. However, the protocol describes how to interpret existing data in a standardized manner in order to select the most suitable animal model, thus avoiding unnecessary animal experiments and misleading translational studies.
Assuntos
Perfilação da Expressão Gênica/métodos , Pesquisa Translacional Biomédica/métodos , Animais , Modelos Animais de Doenças , Humanos , CamundongosRESUMO
The mouse is the main model organism used to study the functions of human genes because most biological processes in the mouse are highly conserved in humans. Recent reports that compared identical transcriptomic datasets of human inflammatory diseases with datasets from mouse models using traditional gene-to-gene comparison techniques resulted in contradictory conclusions regarding the relevance of animal models for translational research. To reduce susceptibility to biased interpretation, all genes of interest for the biological question under investigation should be considered. Thus, standardized approaches for systematic data analysis are needed. We analyzed the same datasets using gene set enrichment analysis focusing on pathways assigned to inflammatory processes in either humans or mice. The analyses revealed a moderate overlap between all human and mouse datasets, with average positive and negative predictive values of 48 and 57% significant correlations. Subgroups of the septic mouse models (i.e., Staphylococcus aureus injection) correlated very well with most human studies. These findings support the applicability of targeted strategies to identify the optimal animal model and protocol to improve the success of translational research.
Assuntos
Modelos Animais de Doenças , Redes Reguladoras de Genes , Biologia de Sistemas/métodos , Pesquisa Translacional Biomédica/métodos , Animais , Perfilação da Expressão Gênica , Humanos , Camundongos , Sepse/genética , Sepse/patologiaRESUMO
Massively increasing global incidences of colorectal cancer require efficient treatment and prevention strategies. Here, we report unexpected anticancerogenic effects of hydroethanolic Iberis amara extract (IAE), which is known as a widely used phytomedical product for treating gastrointestinal complaints. IAE significantly inhibited the proliferation of HT-29 and T84 colon carcinoma cells with an inhibitory concentration (IC50) of 6 and 9 µg/ml, respectively, and further generated inhibitory effects in PC-3 prostate and MCF7 breast cancer cells. Inhibition of proliferation in HT-29 cells was associated with a G2/M phase cell cycle arrest including reduced expression of various regulatory marker proteins. Notably, in HT-29 cells IAE further induced apoptosis by intracellular formation of reactive oxygen species (ROS). Consistent with predictions derived from our in vitro experiments, bidaily oral gavage of 50 mg/kg of IAE over 4 weeks resulted in significant inhibition of tumor growth in a mouse HT-29 tumor xenograft model. Taken together, Iberis amara extracts could become useful alternatives for preventing and treating the progression of colon cancer.
Assuntos
Brassicaceae/química , Neoplasias do Colo/prevenção & controle , Extratos Vegetais/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Animais , Divisão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Neoplasias do Colo/patologia , Xenoenxertos , Humanos , CamundongosRESUMO
We show here if under physiologically relevant conditions resveratrol (RSV) remains stable or not. We further show under which circumstances various oxidation products of RSV such as ROS can be produced. For example, in addition to the widely known effect of bicarbonate ions, high pH values promote the decay of RSV. Moreover, we analyse the impact of reduction of the oxygen partial pressure on the pH-dependent oxidation of RSV. For further interpretation and discussion of these focused data in a broader context we refer to the article "Hormetic shifting of redox environment by pro-oxidative resveratrol protects cells against stress" (Plauth et al., in press) [1].
RESUMO
Resveratrol has gained tremendous interest owing to multiple reported health-beneficial effects. However, the underlying key mechanism of action of this natural product remained largely controversial. Here, we demonstrate that under physiologically relevant conditions major biological effects of resveratrol can be attributed to its generation of oxidation products such as reactive oxygen species (ROS). At low nontoxic concentrations (in general <50µM), treatment with resveratrol increased viability in a set of representative cell models, whereas application of quenchers of ROS completely truncated these beneficial effects. Notably, resveratrol treatment led to mild, Nrf2-specific gene expression reprogramming. For example, in primary epidermal keratinocytes derived from human skin this coordinated process resulted in a 1.3-fold increase of endogenously generated glutathione (GSH) and subsequently in a quantitative reduction of the cellular redox environment by 2.61mVmmol GSH per g protein. After induction of oxidative stress by using 0.78% (v/v) ethanol, endogenous generation of ROS was consequently reduced by 24% in resveratrol pre-treated cells. In contrast to the common perception that resveratrol acts mainly as a chemical antioxidant or as a target protein-specific ligand, we propose that the cellular response to resveratrol treatment is essentially based on oxidative triggering. In physiological microenvironments this molecular training can lead to hormetic shifting of cellular defense towards a more reductive state to improve physiological resilience to oxidative stress.
Assuntos
Fibroblastos/efeitos dos fármacos , Hormese , Queratinócitos/efeitos dos fármacos , Fator 2 Relacionado a NF-E2/genética , Espécies Reativas de Oxigênio/metabolismo , Estilbenos/farmacologia , Antioxidantes/farmacologia , Etanol/farmacologia , Fibroblastos/citologia , Regulação da Expressão Gênica , Glutationa/metabolismo , Células HT29 , Células HeLa , Células Hep G2 , Humanos , Queratinócitos/citologia , Fator 2 Relacionado a NF-E2/metabolismo , Oxirredução , Estresse Oxidativo , Cultura Primária de Células , ResveratrolRESUMO
A common building block for the synthesis of amorfrutin and cajaninstilbene acid derivatives has been developed. The library of synthesized compounds has enabled identification of new nontoxic ligands of peroxisome proliferator-activated receptors (PPAR) and potential inhibitors of the transcriptional corepressor protein NCoR. The biological data holds promise in identification of new potential leads for the antidiabetic drug discovery process.
Assuntos
Hipoglicemiantes/síntese química , Receptores Ativados por Proliferador de Peroxissomo/química , Salicilatos/síntese química , Estilbenos/síntese química , Hipoglicemiantes/química , Ligantes , Estrutura Molecular , Receptores Ativados por Proliferador de Peroxissomo/metabolismo , Salicilatos/química , Estilbenos/químicaRESUMO
BACKGROUND: Although coil embolization is known to prevent rebleeding from acutely ruptured cerebral aneurysms, the underlying biological and mechanical mechanisms have not been characterized. We sought to determine if microcoil-dependent interactions with thrombus induce structural and mechanical changes in the adjacent fibrin network. Such changes could play an important role in the prevention of aneurysm rebleeding. METHODS: The stiffness of in vitro human blood clots and coil-clot complexes implanted into aneurysm phantoms were measured immediately after formation and after retraction for 3 days using unconfined uniaxial compression assays. Scanning electron microscopy of the coil-clot complexes showed the effect of coiling on clot structure. RESULTS: The coil packing densities achieved were in the range of clinical practice. Bare platinum coils increased clot stiffness relative to clot alone (Young's modulus 6.9 kPa and 0.83 kPa, respectively) but did not affect fibrin structure. Hydrogel-coated coils prevented formation of a clot and had no significant effect on clot stiffness (Young's modulus 2 kPa) relative to clot alone. Clot age decreased fiber density by 0.2 fibers/µm(2) but not the stiffness of the bare platinum coil-clot complex. CONCLUSIONS: The stiffness of coil-clot complexes is related to the summative stiffness of the fibrin network and associated microcoils. Hydrogel-coated coils exhibit significantly less stiffness due to the mechanical properties of the hydrogel and the inhibition of fibrin network formation by the hydrogel. These findings have important implications for the design and engineering of aneurysm occlusion devices.
Assuntos
Coagulação Sanguínea , Embolização Terapêutica/métodos , Procedimentos Endovasculares/métodos , Fibrina , Aneurisma Intracraniano/terapia , Modelos Cardiovasculares , Fenômenos Biomecânicos/fisiologia , Coagulação Sanguínea/fisiologia , Materiais Revestidos Biocompatíveis , Humanos , Aneurisma Intracraniano/fisiopatologiaRESUMO
Over the last decades polyetiological metabolic diseases such as obesity and type 2 diabetes have emerged as a global epidemic. Efficient strategies for prevention and treatment include dietary intervention and the development of validated nutraceuticals. Safe extracts of edible plants provide a resource of structurally diverse molecules that can effectively interfere with multifactorial diseases. In this study, we describe the application of ethanolic lemon balm (Melissa officinalis) leaves extract for the treatment of insulin-resistance and dyslipidemia in mice. We show that lemon balm extract (LBE) activates the peroxisome proliferator-activated receptors (PPARs), which have key roles in the regulation of whole body glucose and lipid metabolism. Application of LBE (0.6 mg/mL) to human primary adipocytes resulted in specific peroxisome proliferator-activated receptor target gene expression. LBE treatment of insulin-resistant high-fat diet-fed C57BL/6 mice (200 mg/kg/day) for 6 weeks considerably reduced hyperglycemia and insulin resistance, plasma triacylglycerol, nonesterified fatty acids and LDL/VLDL cholesterol levels. Taken together, ethanolic lemon balm extract can potentially be used to prevent or concomitantly treat type 2 diabetes and associated disorders such as dyslipidemia and hypercholesterolemia.
Assuntos
Hipoglicemiantes/farmacologia , Hipolipemiantes/farmacologia , Melissa/química , Extratos Vegetais/farmacologia , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Animais , Células Cultivadas , Dislipidemias/prevenção & controle , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Resistência à Insulina , Camundongos Endogâmicos C57BL , Camundongos Obesos , PPAR alfa/metabolismo , PPAR gama/metabolismoRESUMO
Given the significant increases in the incidence of metabolic diseases, efficient strategies for preventing and treating of these common disorders are urgently needed. This includes the development of phytopharmaceutical products or functional foods to prevent or cure metabolic diseases. Plant extracts from edible biomaterial provide a potential resource of structurally diverse molecules that can synergistically interfere with complex disorders. In this study we describe the safe application of ethanolic chamomile (Matricaria recutita) flowers extract (CFE) for the treatment and prevention of type 2 diabetes and associated disorders. We show in vitro that this extract activates in particular nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) and its isotypes. In a cellular context, in human primary adipocytes CFE administration (300 µg/ml) led to specific expression of target genes of PPARγ, whereas in human hepatocytes CFE-induced we detected expression changes of genes that were regulated by PPARα. In vivo treatment of insulin-resistant high-fat diet (HFD)-fed C57BL/6 mice with CFE (200 mg/kg/d) for 6 weeks considerably reduced insulin resistance, glucose intolerance, plasma triacylglycerol, non-esterified fatty acids (NEFA) and LDL/VLDL cholesterol. Co-feeding of lean C57BL/6 mice a HFD with 200 mg/kg/d CFE for 20 weeks showed effective prevention of fatty liver formation and hepatic inflammation, indicating additionally hepatoprotective effects of the extract. Moreover, CFE treatment did not reveal side effects, which have otherwise been associated with strong synthetic PPAR-targeting molecules, such as weight gain, liver disorders, hemodilution or bone cell turnover. Taken together, modulation of PPARs and other factors by chamomile flowers extract has the potential to prevent or treat type 2 diabetes and related disorders.
Assuntos
Camomila/química , Flores/química , Regulação da Expressão Gênica/efeitos dos fármacos , Hipoglicemiantes/farmacologia , Receptores Ativados por Proliferador de Peroxissomo/genética , Extratos Vegetais/farmacologia , Transcrição Gênica/efeitos dos fármacos , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Animais , Linhagem Celular , Células Cultivadas , Dieta Hiperlipídica , Relação Dose-Resposta a Droga , Dislipidemias/tratamento farmacológico , Dislipidemias/genética , Dislipidemias/metabolismo , Fígado Gorduroso/genética , Fígado Gorduroso/metabolismo , Fígado Gorduroso/prevenção & controle , Técnicas de Silenciamento de Genes , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Hipoglicemiantes/administração & dosagem , Hipoglicemiantes/efeitos adversos , Resistência à Insulina/genética , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Masculino , Camundongos , Camundongos Obesos , Hepatopatia Gordurosa não Alcoólica , PPAR gama/agonistas , PPAR gama/genética , PPAR gama/metabolismo , Receptores Ativados por Proliferador de Peroxissomo/agonistas , Receptores Ativados por Proliferador de Peroxissomo/metabolismo , Extratos Vegetais/administração & dosagem , Extratos Vegetais/efeitos adversos , Ativação TranscricionalRESUMO
Amorfrutins are a family of natural products with high affinity to the peroxisome proliferator-activated receptor γ (PPARγ), a nuclear receptor regulating lipid and glucose metabolism. The PPARγ agonist rosiglitazone increases insulin sensitivity and is effective against type II diabetes but has severe adverse effects including weight gain. Amorfrutins improve insulin sensitivity and dyslipidemia but do not enhance undesired fat storage. They bear potential as therapeutics or prophylactic dietary supplements. We identified amorfrutin B as a novel partial agonist of PPARγ with a considerably higher affinity than that of previously reported amorfrutins, similar to that of rosiglitazone. Crystal structures reveal the geranyl side chain of amorfrutin B as the cause of its particularly high affinity. Typical for partial agonists, amorfrutins 1, 2, and B bind helix H3 and the ß-sheet of PPARγ but not helix H12.
Assuntos
PPAR gama/química , Salicilatos/química , Cristalografia por Raios X , Agonismo Parcial de Drogas , Genes Reporter , Células HEK293 , Humanos , Estrutura Molecular , PPAR gama/agonistas , PPAR gama/genética , PPAR gama/metabolismo , Salicilatos/metabolismo , EstereoisomerismoRESUMO
OBJECTIVE: The liver X receptor α (LXRα) is a ligand-dependent nuclear receptor and the major regulator of reverse cholesterol transport in macrophages. This makes it an interesting target for mechanistic study and treatment of atherosclerosis. METHODS AND RESULTS: We optimized a promising stilbenoid structure (STX4) in order to reach nanomolar effective concentrations in LXRα reporter-gene assays. STX4 displayed the unique property to activate LXRα effectively but not its subtype LXRß. The potential of STX4 to increase transcriptional activity as an LXRα ligand was tested with gene expression analyses in THP1-derived human macrophages and oxLDL-loaded human foam cells. Only in foam cells but not in macrophage cells STX4 treatment showed athero-protective effects with similar potency as the synthetic LXR ligand T0901317 (T09). Surprisingly, combinatorial treatment with STX4 and T09 resulted in an additive effect on reporter-gene activation and target gene expression. In physiological tests the cellular content of total and esterified cholesterol was significantly reduced by STX4 without the undesirable increase in triglyceride levels as observed for T09. CONCLUSIONS: STX4 is a new LXRα-ligand to study transcriptional regulation of anti-atherogenic processes in cell or ex vivo models, and provides a promising lead structure for pharmaceutical development.