Upregulation of vitamin D-binding protein is associated with changes in insulin production in pancreatic beta-cells exposed to p,p′-DDT and p,p′-DDE

Abstract

Persistent organochlorine pollutants (POPs) gradually accumulate in the human organism due to their presence in the environment. Some studies have described a correlation between the level of POPs in the human body and the incidence of diabetes, but we know little about the direct effect of POPs on pancreatic beta-cells. We exposed pancreatic beta-cells INS1E to non-lethal concentrations of p,p′-DDT (1,1′-(2,2,2-Trichloroethane-1,1-diyl)bis(4-chlorobenzene)) and p,p′-DDE (1,1′-(2,2-dichloroethene-1,1-diyl)bis(4-chlorobenzene)) for 1 month, and assessed changes in protein expression and the intracellular insulin level. 2-D electrophoresis revealed 6 proteins with changed expression in cells exposed to p,p′-DDT or p,p′-DDE. One of the detected proteins – vitamin D-binding protein (VDBP) – was upregulated in both cells exposed to p,p′-DDT, and cells exposed to p,p′-DDE. Both exposures to pollutants reduced the intracellular level of insulin mRNA, proinsulin, and insulin monomer; p,p′-DDT also slightly reduced the level of hexameric insulin. Overexpression of VDBP caused by the stable transfection of beta-cells with the gene for VDBP decreased both the proinsulin and hexameric insulin level in beta-cells similarly to the reduction detected in cells exposed to p,p′-DDT. Our data suggest that in the cells exposed to p,p′-DDT and p,p′-DDE, the increased VDBP protein level decreased the proinsulin expression in an unknown mechanism.

Development of in vitro test methods in a model of human pancreatic β-cells to identify metabolism disrupting chemicals with diabetogenic activity

“…DDE is a metabolite of the persistent endocrine disruptor DDT. Previous experiments performed in INS-1E cells showed that exposure to non-lethal concentrations of DDT or DDE changed insulin secretion and content/expression [58,68]. Upon 48 h treatment, low concentrations of DDT (1 fM to 1 μM) decreased GSIS in a non-monotonic manner, while all doses tested diminished intracellular insulin content [68].…”

“…Upon 48 h treatment, low concentrations of DDT (1 fM to 1 μM) decreased GSIS in a non-monotonic manner, while all doses tested diminished intracellular insulin content [68]. In addition, INS-1E cells exposed for 1 month to a non-lethal concentration (10 μM) of DDT or DDE had lower mRNA levels of Ins1 and Ins2 as well as reduced expression of proinsulin and insulin [58]. On the other hand, DDE exposure increased insulin secretion in β-TC-6 cells [69], which agrees with our results that suggest an increase of GSIS at 10 nM and 1 μM DDE (insulin content remained unchanged in all concentrations tested).…”

“…Despite the lack of evidence in pancreatic β-cells, it has been shown that exposure to high doses of TPP and DDE (>10 μM) induced apoptosis in other cells and tissues: TPP in hepatocytes, epithelial tumoral JEG-3 cells from placenta, and murine BV-2 microglia [53–55]; and DDE in Sertoli cells [56,57]. Exposure to high concentrations of p,p’ -DDT (>150 μM) for 24 h decreased viability in NES2Y human pancreatic β-cell line [58]. Lack of publications with these EDCs at low concentrations does not allow comparison with the present findings.…”

Markers of acute toxicity of DDT exposure in pancreatic beta-cells determined by a proteomic approach

“…In our previous study, we used 2-D electrophoresis coupled to mass spectrometry to find proteins possibly involved in mechanisms mediating a prolonged (1 month) effect of non-lethal concentrations of organochlorine pollutant p , p ‘-DDT in pancreatic beta-cells [ 6 , 21 ]. In our present study, we aimed to find proteins that change expression in NES2Y human pancreatic beta-cells when exposed to a high concentration of p , p ‘-DDT) and could be detected by 2-D electrophoresis.…”

Markers of Acute Toxicity in Pancreatic Beta-Cells Exposed to Lethal Doses of the Organochlorine Pollutant DDT Determined by a Proteomic Approach

“…In our previous study, we used 2-D electrophoresis coupled to mass spectrometry to find proteins possibly involved in mechanisms mediating prolonged (1 month) effect of non-lethal doses of organochlorine pollutant p,p ’-DDT in pancreatic beta-cells (6, 18). In our present study, we aimed to find markers of acute toxicity of lethal doses of p,p ’-DDT in human pancreatic beta-cells NES2Y, also employing 2-D electrophoresis.…”