Excessive iron induces oxidative stress promoting cellular perturbations and insulin secretory dysfunction in MIN6 beta cells

Voni Blesia, Vinood B Patel, Hisham Al-Obaidi, Derek Renshaw, Mohammed Gulrez Zariwala

    Research output: Contribution to journalArticlepeer-review

    16 Citations (Scopus)
    19 Downloads (Pure)

    Abstract

    Exposure to high levels of glucose and iron are co-related to reactive oxygen species (ROS) generation and dysregulation of insulin synthesis and secretion, although the precise mechanisms are not well clarified. The focus of this study was to examine the consequences of exposure to high iron levels on MIN6 β-cells. MIN6 pseudoislets were exposed to 20 µM (control) or 100 µM (high) iron at predefined glucose levels (5.5 mM and 11 mM) at various time points (3, 24, 48 & 72 h). Total iron content was estimated by a colourimetric ferrozine assay in presence or absence of transferrin-bound iron. Cell viability was assessed by a resazurin dye-based assay, and ROS mediated cellular oxidative stress was assessed by estimating malondialdehyde levels. β-cell iron absorption was de-termined by a ferritin immunoassay. Cellular insulin release and content was measured by an insu-lin immunoassay. Expression of SNAP-25, a key protein in the core SNARE complex that modulates vesicle exocytosis, was measured by immunoblotting. Our results demonstrate that exposure to high iron levels resulted in a 15-fold (48 h) and 4-fold (72 h) increase in cellular iron accumulation. These observations were consistent with data from oxidative stress analysis which demonstrated 2.69-fold higher levels of lipid peroxidation. Furthermore, exposure to supraphysiological (11 mM) levels of glucose and high iron (100 µM) at 72 h exerted the most detrimental effect on the MIN6 β-cell viability. The effect of high iron exposure on total cellular iron content was identical in the pres-ence or absence of transferrin. High iron exposure (100 µM) resulted in a decrease of MIN6 insulin secretion (64% reduction) as well as cellular insulin content (10% reduction). Finally, a significant reduction in MIN6 β-cell SNAP-25 protein expression was evident at 48 h upon exposure to 100 µM iron. Our data suggest that exposure to high iron and glucose concentrations results in cellular ox-idative damage and may initiate insulin secretory dysfunction in pancreatic β-cells by modulation of the exocytotic machinery.
    Original languageEnglish
    Article number1141
    Number of pages20
    JournalCells
    Volume10
    Issue number5
    DOIs
    Publication statusPublished - 9 May 2021

    Bibliographical note

    This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

    Keywords

    • excess iron
    • oxidative stress
    • impaired insulin secretion
    • type 2 diabetes mellitus;
    • β-cell
    • type 2 diabetes mellitus

    ASJC Scopus subject areas

    • Medicine(all)

    Fingerprint

    Dive into the research topics of 'Excessive iron induces oxidative stress promoting cellular perturbations and insulin secretory dysfunction in MIN6 beta cells'. Together they form a unique fingerprint.

    Cite this