Mono(2-ethylhexyl) phthalate (MEHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) but not di(2-ethylhexyl) phthalate (DEHP) bind productively to the peroxisome proliferator-activated receptor ?.

ABSTRACT: RATIONALE:The most frequently occurring phthalate, di(2-ethylhexyl) phthalate (DEHP), causes adverse effects on glucose homeostasis and insulin sensitivity in several cell models and epidemiological studies. However, thus far, there is no information available on the molecular interaction of phthalates and one of the key regulators of the metabolism, the peroxisome proliferator-activated receptor gamma (PPAR?). Since the endogenous ligand of PPAR?, 15-deoxy-delta-12,14-prostaglandin J2 (15?-PGJ2 ), features structural similarity to DEHP and its main metabolites produced in human hepatic metabolism, mono(2-ethylhexyl) phthalate (MEHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), we tested the hypothesis of direct interactions between PPAR? and DEHP or its transformation products. METHODS:Hydrogen/deuterium exchange mass spectrometry (HDX-MS) and docking were conducted to obtain structural insights into the interactions and surface plasmon resonance (SPR) analysis to reveal information about binding levels. To confirm the activation of PPAR? upon ligand binding on the cellular level, the GeneBLAzer® bioassay was performed. RESULTS:HDX-MS and SPR analyses demonstrated that the metabolites MEHP and MEOHP, but not DEHP itself, bind to the ligand binding pocket of PPAR?. This binding leads to typical activation-associated conformational changes, as observed with its endogenous ligand 15?-PGJ2 . Furthermore, the reporter gene assay confirmed productive interaction. DEHP was inactive up to a concentration of 14??M, while the metabolites MEHP and MEOHP were active at low micromolar concentrations. CONCLUSIONS:In summary, this study gives structural insights into the direct interaction of PPAR? with MEHP and MEOHP and shows that the DEHP transformation products may modulate the lipid metabolism through PPAR? pathways.

SUBMITTER: Kratochvil I 

PROVIDER: S-EPMC6367069 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature