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Zinc transporter gene expression is regulated by pro-inflammatory cytokines: a potential role for zinc transporters in beta-cell apoptosis?

ABSTRACT: BACKGROUND:Beta-cells are extremely rich in zinc and zinc homeostasis is regulated by zinc transporter proteins. beta-cells are sensitive to cytokines, interleukin-1beta (IL-1beta) has been associated with beta-cell dysfunction and -death in both type 1 and type 2 diabetes. This study explores the regulation of zinc transporters following cytokine exposure. METHODS:The effects of cytokines IL-1beta, interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) on zinc transporter gene expression were measured in INS-1-cells and rat pancreatic islets. Being the more sensitive transporter, we further explored ZnT8 (Slc30A8): the effect of ZnT8 over expression on cytokine induced apoptosis was investigated as well as expression of the insulin gene and two apoptosis associated genes, BAX and BCL2. RESULTS:Our results showed a dynamic response of genes responsible for beta-cell zinc homeostasis to cytokines: IL-1beta down regulated a number of zinc-transporters, most strikingly ZnT8 in both islets and INS-1 cells. The effect was even more pronounced when mixing the cytokines. TNF-alpha had little effect on zinc transporter expression. IFN-gamma down regulated a number of zinc transporters. Insulin expression was down regulated by all cytokines. ZnT8 over expressing cells were more sensitive to IL-1beta induced apoptosis whereas no differences were observed with IFN-gamma, TNF-alpha, or a mixture of cytokines. CONCLUSION:The zinc transporting system in beta-cells is influenced by the exposure to cytokines. Particularly ZnT8, which has been associated with the development of diabetes, seems to be cytokine sensitive.

SUBMITTER: Egefjord L

PROVIDER: S-EPMC2651882 | biostudies-literature | 2009 Feb

REPOSITORIES: biostudies-literature

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Zinc transporter gene expression is regulated by pro-inflammatory cytokines: a potential role for zinc transporters in beta-cell apoptosis?

Egefjord Laerke L Jensen Jens Ledet JL Bang-Berthelsen Claus Heiner CH Petersen Andreas Brønden AB Smidt Kamille K Schmitz Ole O Karlsen Allan Ertman AE Pociot Flemming F Chimienti Fabrice F Rungby Jørgen J Magnusson Nils E NE

BMC endocrine disorders 20090225

<h4>Background</h4>Beta-cells are extremely rich in zinc and zinc homeostasis is regulated by zinc transporter proteins. beta-cells are sensitive to cytokines, interleukin-1beta (IL-1beta) has been associated with beta-cell dysfunction and -death in both type 1 and type 2 diabetes. This study explores the regulation of zinc transporters following cytokine exposure.<h4>Methods</h4>The effects of cytokines IL-1beta, interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) on zinc ...[more]

PMID: 19243577

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Project description:BackgroundZinc (Zn) and iron (Fe) are essential micronutrients for plant growth and development, their deficiency or excess severely impaired physiological and biochemical reactions of plants. Therefore, a tightly controlled zinc and iron uptake and homeostasis network has been evolved in plants. The Zinc-regulated transporters, Iron-regulated transporter-like Proteins (ZIP) are capable of uptaking and transporting divalent metal ion and are suggested to play critical roles in balancing metal uptake and homeostasis, though a detailed analysis of ZIP gene family in maize is still lacking.ResultsNine ZIP-coding genes were identified in maize genome. It was revealed that the ZmZIP proteins share a conserved transmembrane domain and a variable region between TM-3 and TM-4. Transiently expression in onion epidermal cells revealed that all ZmZIP proteins were localized to the endoplasmic reticulum and plasma membrane. The yeast complementation analysis was performed to test the Zn or Fe transporter activity of ZmZIP proteins. Expression analysis showed that the ZmIRT1 transcripts were dramatically induced in response to Zn- and Fe-deficiency, though the expression profiles of other ZmZIP changed variously. The expression patterns of ZmZIP genes were observed in different stages of embryo and endosperm development. The accumulations of ZmIRT1 and ZmZIP6 were increased in the late developmental stages of embryo, while ZmZIP4 was up-regulated during the early development of embryo. In addition, the expression of ZmZIP5 was dramatically induced associated with middle stage development of embryo and endosperm.ConclusionsThese results suggest that ZmZIP genes encode functional Zn or Fe transporters that may be responsible for the uptake, translocation, detoxification and storage of divalent metal ion in plant cells. The various expression patterns of ZmZIP genes in embryo and endosperm indicates that they may be essential for ion translocation and storage during differential stages of embryo and endosperm development. The present study provides new insights into the evolutionary relationship and putative functional divergence of the ZmZIP gene family during the growth and development of maize.

Project description:BackgroundAdult human pancreatic beta cells are the "gold standard" for studies on diabetes pathogenesis, but their use is limited by insufficient availability and variable quality. An important effort has recently taken place to differentiate beta cells from human induced pluripotent stem cells (iPSCs) and validate their use for diabetes research. We presently used a 7-stage protocol to generate beta cells from human iPSC and evaluated whether these cells are responsive to the pro-inflammatory cytokines (IFN?, IL-1?, or IFN?) that play a role in type 1 diabetes.MethodsThe iPSC-derived islet-like cell clusters contained 40-50% beta and 10-15% alpha cells and expressed the receptors for IFN?, IL-1?, or IFN?. Cells were exposed to either IFN? (1000?U/mL)?+?IL-1? (50?U/mL) or IFN? alone (2000?U/mL) for 24/48?h. Apoptosis was quantified using Hoechst/propidium iodide staining or the RealTime Glo Apoptosis Kit (Promega). After treatment, CXCL10 secretion was quantified by ELISA. The expression of multiples genes (Ins, Gcg, Nkx2.2, Nkx6.1, Pdx1, Mafa, BiP, Chop, Atf3, CXCL10, CXCL9, CCL5, and HLA-ABC) was quantified by RT-qPCR. Phosphorylation state and total expression of STAT1/STAT2, as well as expression of PDL1 and of the ER chaperone BiP, were quantified by Western blotting. The co-localization of HLA-ABC or cleaved caspase-3 and Ins/Gcg expression was assessed by immunohistochemistry. The presence of HLA-ABC at the plasma membrane was measured by flow cytometry.ResultsIFN? + IL-1? and IFN? induced apoptosis of the cells after 48?h of exposure. Cleaved caspase-3 co-localized mostly but not exclusively with Ins+ cells. Exposure to IFN? + IL-1? induced a pro-inflammatory phenotype, including increased CXCL10, CXCL9, and CCL5 expression; CXCL10 secretion; and HLA-ABC expression. HLA overexpression was confirmed at the protein level by Western blotting and flow cytometry. Exposure to IFN? + IL-1? (but not IFN?) also induced beta cell dedifferentiation and endoplasmic reticulum stress (increase in BiP, Chop, and Atf3 mRNA expression). Phosphorylation of STAT1 was stimulated already after 1?h by IFN? + IL-1? and IFN?, while phosphorylation of STAT2 was only activated by IFN? at 1-4 h. PDL1 expression was increased by both IFN? + IL-1? and IFN?.ConclusionsOur data show that human iPSC-derived beta cells respond to pro-inflammatory cytokines IL-1? + IFN? and IFN?, by activating the same pathogenic processes as adult human primary beta cells. These cells thus represent a valuable tool for future research on the pathogenesis of type 1 diabetes.

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Zinc transporter gene expression is regulated by pro-inflammatory cytokines: a potential role for zinc transporters in beta-cell apoptosis?

Publications

Zinc transporter gene expression is regulated by pro-inflammatory cytokines: a potential role for zinc transporters in beta-cell apoptosis?

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