ABSTRACT
Withaferin A (WA), a natural phytochemical derived from the plant Withania somnifera, is a well-studied bioactive compound exerting a broad spectrum of health promoting effects. To gain better insight in the potential therapeutic capacity of WA, we evaluated the transcriptional effects of WA on primary human umbilical vein endothelial cells (HUVECs) and an endothelial cell line (EA.hy926). RNA microarray analysis of WA treated HUVEC cells demonstrated increased expression of the antioxidant gene heme oxygenase (HO-1). Transcriptional regulation of this gene is strongly dependent on the transcription factor NF-E2-related factor 2 (Nrf2), which senses chemical changes in the cell and coordinates transcriptional responses to maintain chemical homeostasis via expression of antioxidant genes and cytoprotective Phase II detoxifying enzymes. Under normal conditions, Nrf2 is kept in the cytoplasm by Kelch-like ECH-associated protein 1 (Keap1), an adaptor protein controlling the half-life of Nrf2 via constant proteasomal degradation. In this study we demonstrate that WA time- and concentration-dependently induces HO-1 expression in endothelial cells via upregulation and increased nuclear translocation of Nrf2. According to the crucial negative regulatory role of Keap1 in Nrf2 expression levels, a direct interaction of WA with Keap1 could be demonstrated. In vitro and in silico evaluations suggest that specific cysteine residues in Keap1 might be involved in the interaction with WA.
Subject(s)
Gene Expression Regulation/drug effects , Heme Oxygenase-1/genetics , Kelch-Like ECH-Associated Protein 1/genetics , NF-E2-Related Factor 2/genetics , Withanolides/pharmacology , A549 Cells , Cell Survival/drug effects , Crystallography, X-Ray , Gene Expression Profiling , HEK293 Cells , Heme Oxygenase-1/metabolism , Human Umbilical Vein Endothelial Cells/cytology , Human Umbilical Vein Endothelial Cells/drug effects , Human Umbilical Vein Endothelial Cells/metabolism , Humans , Hybridomas/cytology , Hybridomas/drug effects , Hybridomas/metabolism , Kelch-Like ECH-Associated Protein 1/chemistry , Kelch-Like ECH-Associated Protein 1/metabolism , Metabolic Detoxication, Phase II/genetics , Molecular Docking Simulation , NF-E2-Related Factor 2/agonists , NF-E2-Related Factor 2/antagonists & inhibitors , NF-E2-Related Factor 2/metabolism , Oligonucleotide Array Sequence Analysis , Protein Binding , Protein Domains , Protein Structure, Secondary , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , Signal Transduction , Transcription, Genetic , Withanolides/chemistryABSTRACT
Herbal medicine which involves the use of plants for their medicinal value, dates as far back as the origin of mankind and demonstrates an array of applications including cardiovascular protection and anti-cancer activities, via antioxidant, anti-inflammatory and metabolic activities. Even today the popularity of medicinal herbs is still growing like in traditional medicines such as the Indian medicine, Ayurveda. One of the Ayurvedic medicinal plants is Withania somnifera Dunal, of which the important constituents are the withanolides. Among them, Withaferin A is one of the most bioactive compounds, exerting anti-inflammatory, pro-apoptotic but also anti-invasive and anti-angiogenic effects. In the context of modern pharmacology, a better insight in the underlying mechanism of the broad range of bioactivities exerted by Withaferin A is compulsory. Therefore, a lot of effort was made to explore the intracellular effects of Withaferin A and to characterize its target proteins. This review provides a decisive insight on the molecular basis of the health-promoting potential of Withaferin A.
Subject(s)
Antineoplastic Agents/pharmacology , Withanolides/pharmacology , Angiogenesis Inhibitors/chemistry , Angiogenesis Inhibitors/pharmacology , Animals , Anti-Inflammatory Agents/chemistry , Anti-Inflammatory Agents/pharmacology , Antineoplastic Agents/chemistry , Apoptosis/drug effects , Cell Line, Tumor , Heat-Shock Proteins/metabolism , Humans , NF-kappa B/metabolism , Proteasome Endopeptidase Complex/metabolism , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Transcription, Genetic , Withanolides/chemistryABSTRACT
SCOPE: The aim of the study was to examine the atheroprotective effect of dietary curcumin in a mouse model of atherosclerosis and to identify its cellular and molecular targets at the vascular level. METHODS AND RESULTS: ApoE(-/-) mice were fed with curcumin at 0.2% (wt/wt) in diet for 4 months. This supplementation reduced the extent of atherosclerotic lesion by 26% and induced changes in expression of genes implicated in cell adhesion and transendothelial migration or cytoskeleton organization, as revealed by a transcriptomic analysis in the aorta. Expression profile of these genes suggests reduction in both leukocyte adhesion and transendothelial migration. In agreement with this hypothesis, we observed a reduction (-37%) in macrophage infiltration in the plaque, as measured by immunohistochemistry, and, in vitro, a lower adhesion of monocytes to TNF-α-stimulated endothelial cells (-32%) after exposure to a nutritionally achievable concentration of curcumin. These changes in gene expression could be related to the observed increased expression of IκB protein and decrease of TNF-α-induced NF-κB/DNA binding and NF-κB-transcriptional activity upon exposure to curcumin. CONCLUSION: Our findings pointed out that the antiatherogenic effect of curcumin could be linked to its effect on gene networks and cell functions related to leukocyte adhesion and transendothelial migration via NF-κB-dependent pathways.
