title: Di(2-ethylhexyl) phthalate-induced apoptosis in rat INS-1 cells is dependent on activation of endoplasmic reticulum stress and suppression of antioxidant protection.
abstract: Di(2-ethylhexyl) phthalate (DEHP) is used as plasticizer and is ubiquitously found in the environment. Exposure to DEHP has been linked to an increased incidence of type 2 diabetes. Pancreatic β-cell dysfunction is a hallmark of type 2 diabetes; however, it is unknown whether DEHP exposure contributes to this risk. Here, we aimed to investigate the cytotoxic effects of DEHP on INS-1 cells and to further explore the related underlying mechanisms. INS-1 cells were exposed to 0, 5, 25, 125 or 625 μM DEHP for 24 hrs. Cell viability, glucose-stimulated insulin secretion, reactive oxygen species (ROS) generation, cellular antioxidant response, Ca(2+) homoeostasis and the levels of genes and proteins involved in endoplasmic reticulum (ER) stress were measured. The results showed that DEHP decreased insulin secretion and content and induced apoptosis in INS-1 cells in a dose-dependent manner. Furthermore, ROS generation was increased and Nrf2-dependent antioxidant defence protection was dysregulated in INS-1 cells after DEHP exposure. Most importantly, DEHP effectively depleted ER Ca(2+) and triggered the ER stress response as demonstrated by the elevated transcription and translation of the ER chaperone GRP78 and GRP94, the increased phosphorylation of protein kinase R-like endoplasmic reticulum kinase (PERK) and its downstream substrate eukaryotic translation initiation factor 2α (eIF2α), as well as the increased levels of activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP). Taken together, DEHP exerted toxic effects on INS-1 cells by inducing apoptosis, which is dependent on the activation of the PERK-ATF4-CHOP ER stress signalling pathway and the suppression of Nrf2-dependent antioxidant protection.
authors.affiliation: Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Sun
authors.forename: Yi
authors.initials: Y
authors.lastname: Lin
authors.forename: Qiansheng
authors.initials: Q
authors.lastname: Huang
authors.forename: Junpeng
authors.initials: J
authors.lastname: Shi
authors.forename: Ling
authors.initials: L
authors.lastname: Qiu
authors.forename: Mei
authors.initials: M
authors.lastname: Kang
authors.forename: Yajie
authors.initials: Y
authors.lastname: Chen
authors.forename: Chao
authors.initials: C
authors.lastname: Fang
authors.forename: Ting
authors.initials: T
authors.lastname: Ye
authors.forename: Sijun
authors.initials: S
authors.lastname: Dong
mesh_terms: D051701:Activating Transcription Factor 4 / Q000378:metabolism; D000818:Animals; D000975:Antioxidants; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004051:Diethylhexyl Phthalate / Q000494:pharmacology*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008562:Membrane Glycoproteins / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D051742:Transcription Factor CHOP / Q000378:metabolism; D019892:eIF-2 Kinase / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP
chemical_list: D051701:Activating Transcription Factor 4; D000975:Antioxidants; D002118:Calcium; D004051:Diethylhexyl Phthalate; D015852:Eukaryotic Initiation Factor-2; D005947:Glucose; D006360:Heat-Shock Proteins; D007328:Insulin; D008562:Membrane Glycoproteins; D051267:NF-E2-Related Factor 2; D017382:Reactive Oxygen Species; D051742:Transcription Factor CHOP; D019892:eIF-2 Kinase; C497110:Atf4 protein, rat; C497251:Ddit3 protein, rat; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP; C495637:Nfe2l2 protein, rat; C053387:endoplasmin
keywords: Di(2-ethylhexyl) phthalate; apoptosis; endoplasmic reticulum stress; oxidative damage; β cells