Duodenal biopsies are considered a suitable source of enterocytes for studies of dietary iron absorption. However, the expression level of molecules involved in iron absorption may vary along the length of duodenum. We aimed to determine whether the expression of molecules involved in the absorption of heme and non-heme iron differs depending on the location in the duodenum. Analysis was performed with samples of duodenal biopsies from 10 individuals with normal iron metabolism. Samples were collected at the following locations: (a) immediately post-bulbar, (b) 1-2 cm below the papilla of Vater and (c) in the distal duodenum. The gene expression was analyzed at the mRNA and protein level using real-time PCR and Western blot analysis. At the mRNA level, significantly different expression of HCP1, DMT1, ferroportin and Zip8 was found at individual positions of duodenum. Position-dependent expression of other molecules, especially of FLVCR1, HMOX1 and HMOX2 was also detected but with no statistical significances. At the protein level, we observed statistically significantly decreasing expression of transporters HCP1, FLVCR1, DMT1, ferroportin, Zip14 and Zip8 with advancing positions of duodenum. Our results are consistent with a gradient of diminishing iron absorption along the duodenum for both heme and non-heme iron.

• Keywords
• heme iron absorption, iron transport, iron uptake in duodenum, non-heme iron absorption,
• MeSH
• Duodenum * metabolism   MeSH
• Heme metabolism   MeSH
• Ion Transport MeSH
• Humans MeSH
• RNA, Messenger genetics   metabolism   MeSH
• Iron * metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Heme MeSH
• RNA, Messenger MeSH
• Iron * MeSH

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.

• MeSH
• Insulin-Secreting Cells drug effects   metabolism   MeSH
• Cell Line MeSH
• DDT toxicity   MeSH
• Dichlorodiphenyl Dichloroethylene toxicity   MeSH
• Insulin metabolism   MeSH
• Rats MeSH
• Environmental Pollutants toxicity   MeSH
• Vitamin D-Binding Protein metabolism   MeSH
• Toxicity Tests, Subchronic MeSH
• Up-Regulation drug effects   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• DDT MeSH
• Dichlorodiphenyl Dichloroethylene MeSH
• Insulin MeSH
• Environmental Pollutants MeSH
• Vitamin D-Binding Protein MeSH