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Crystal structure of PPARgamma ligand binding domain in complex with tetrabromo-bisphenol A (TBBPA)Crystal structure of PPARgamma ligand binding domain in complex with tetrabromo-bisphenol A (TBBPA)
Structural highlights
Disease[PPARG_HUMAN] Note=Defects in PPARG can lead to type 2 insulin-resistant diabetes and hyptertension. PPARG mutations may be associated with colon cancer. Defects in PPARG may be associated with susceptibility to obesity (OBESITY) [MIM:601665]. It is a condition characterized by an increase of body weight beyond the limitation of skeletal and physical requirements, as the result of excessive accumulation of body fat.[1] Defects in PPARG are the cause of familial partial lipodystrophy type 3 (FPLD3) [MIM:604367]. Familial partial lipodystrophies (FPLD) are a heterogeneous group of genetic disorders characterized by marked loss of subcutaneous (sc) fat from the extremities. Affected individuals show an increased preponderance of insulin resistance, diabetes mellitus and dyslipidemia.[2] [3] Genetic variations in PPARG can be associated with susceptibility to glioma type 1 (GLM1) [MIM:137800]. Gliomas are central nervous system neoplasms derived from glial cells and comprise astrocytomas, glioblastoma multiforme, oligodendrogliomas, and ependymomas. Note=Polymorphic PPARG alleles have been found to be significantly over-represented among a cohort of American patients with sporadic glioblastoma multiforme suggesting a possible contribution to disease susceptibility. Function[PPARG_HUMAN] Receptor that binds peroxisome proliferators such as hypolipidemic drugs and fatty acids. Once activated by a ligand, the receptor binds to a promoter element in the gene for acyl-CoA oxidase and activates its transcription. It therefore controls the peroxisomal beta-oxidation pathway of fatty acids. Key regulator of adipocyte differentiation and glucose homeostasis. Acts as a critical regulator of gut homeostasis by suppressing NF-kappa-B-mediated proinflammatory responses.[4] [5] [6] Publication Abstract from PubMedBACKGROUND: The occurrence of halogenated analogues of the xeno-estrogen bisphenol-A (BPA) has been recently demonstrated both in environmental and human samples. These include brominated (e.g. tetrabromobisphenol-A; TBBPA) as well as chlorinated (e.g. tetrachlorobisphenol-A; TCBPA) bisphenols which are both flame retardants. Due to their structural homology with BPA, such chemicals are candidate endocrine disruptors. However, their possible target(s) within the nuclear hormone receptor (NHRs) superfamily has remained unknown. OBJECTIVES: We investigated whether BPA and halogenated analogues could be ligands of estrogen (ERs) and peroxysome proliferator-activated (PPARs) receptors and act as endocrine disrupting chemicals (EDCs). METHODS: The activity of compounds was studied using reporter cell lines expressing ERs and PPARs. The binding affinities to PPARgamma were measured by competitive binding assays with [3H]-rosiglitazone. We also investigated the impact of TBBPA and TCBPA on adipocyte differentiation using NIH3T3-L1 cells. Finally, the binding mode of halogenated BPAs to PPARgamma was determined by X-ray crystallography. RESULTS: Two major outcomes of this study are the demonstration that TBBPA and TCBPA are human, zebrafish and xenopus PPARgamma ligands and the discovery of the mechanism by which these chemicals bind to and activate PPARgamma. We also provide evidence that activation of ERalpha, ERbeta and PPARgamma depends on the halogenation degree of BPA analogues. The bulkier brominated BPA analogues, the greater their capability to activate PPARgamma and the weaker their estrogenic potential. CONCLUSIONS: Our results strongly suggest that poly-halogenated bisphenols could function as obesogens by acting as agonists able to disrupt physiological functions regulated by human or animal PPARgamma. Peroxysome Proliferator-Activated Receptor gamma is a Target for Halogenated Analogues of Bisphenol-A.,Riu A, Grimaldi M, le Maire A, Bey G, Phillips K, Boulahtouf A, Perdu E, Zalko D, Bourguet W, Balaguer P Environ Health Perspect. 2011 May 11. PMID:21561829[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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