Heme Oxygenase-1 (HMOX-1) and inhibitor of differentiation proteins (ID1, ID3) are key response mechanisms against iron-overload in pancreatic β-cells

Iron overload promotes the generation of reactive oxygen species (ROS). Pancreatic beta-cells can counter oxidative stress through multiple anti-oxidant responses. Herein, RNA-sequencing was used to describe the expression profile of iron regulatory genes in human islets with or without diabetes. Functional experiments including siRNA silencing, qPCR, western blotting, cell viability, ELISA and RNA-sequencing were performed as means of identifying the genetic signature of the protective response following iron overload-induced stress in human islets and INS-1. FTHI and FTL genes were highly expressed in human islets and INS-1 cells, while hepcidin (HAMP) was low. FXN, DMTI and FTHLI genes were differentially expressed in diabetic islets compared to control. Silencing of Hamp in INS-1 cells impaired insulin secretion and influenced the expression of beta-cell key genes. RNA-sequencing analysis in iron overloaded INS-1 cells identified Idl and Id3 as the top down-regulated genes, while Hmoxl was the top upregulated. Expression of ID1, ID3 and HMOX1 was validated at the protein level in INS-1 cells and human islets. Differentially expressed genes (DEGs) were enriched for TGF-beta, regulating stem cells, fermptosis, and HIF-1 signaling. Hmoxl -silenced cells treated with FAC elevated the expression of Id1 and Id3 expression than untreated cells. Our findings suggest that HMOX1, ID1 and ID3 define the response mechanism against iron-overload-induced stress in beta-cells.