Excess iron accumulation mediated senescence in diabetic kidney injury

Cellular senescence and iron accumulation were separately observed in diabetic nephropathy (DN). Limited evidence supports that iron was significantly accumulated in senescent cells. We aimed to explore whether iron is involved in the pathogenesis role of senescence in DN. Renal cells were treated with high glucose (HG, 35 mM) for 10 or 15 days, and DN mice were induced by high-fat diet and streptozotocin. Gene ontology enrichment, gene set enrichment analysis analysis, β-galactosidase staining, 5-ethynyl-2-deoxyuridine staining, and western blot depicted the upregulated senescence pathway in vitro and in vivo of DN. Lactate dehydrogenase (LDH) release was increased by HG and reversed by p16/p21 knockdown, and the supernatant of HG-treated cells caused increased LDH release from normal cells. Iron metabolism-related protein expression was disordered after HG exposure concomitant with senescence. Ferric ammonium citrate (50 μM) upregulated gamma-H2A.X variant histone and increased the senescence markers in HG-treated cells. The treatment of deferoxamine (0.5 μM) had the opposite effect. Compared to the non-DN individual, increased ferritin and senescence markers were verified in DN mice and patients, and the co-localization of ferritin and senescence markers was observed by immunofluorescence. These results suggested that accumulated iron was correlated with aggravated DNA damage and accelerated senescence, and revealed the role of iron in the cellular senescence of diseases.