Investigation of the mutual crosstalk between ER stress and PI3K/AKT/mTOR signaling pathway in iron overload-induced liver injury in chicks

Iron is an essential element for the normal functioning of living organisms, but excessive iron deposition can lead to organ damage. This study aims to investigate the interaction between the endoplasmic reticulum stress signaling pathway and the PI3K/AKT/mTOR signaling pathway in liver injury induced by iron overload in chicks. Rspectively, 150 one-day-old broilers were divided into three groups and supplemented with 50 (C), 500 (E1), and 1000 (E2) mg ferrous sulfate monohydrate/kg in the basal diet. Samples were taken after continuous feeding for 14 days. The results showed that iron overload could upregulate the levels of ALT and AST. Histopathological examination revealed bleeding in the central vein of the liver accompanied by inflammatory cell infiltration. Hoechst staining showed that the iron overload group showed significant bright blue fluorescence, and ultrastructural observations showed chromatin condensation as well as mitochondrial swelling and cristae disorganization in the iron overload group. RT-qPCR and Western blot results showed that iron overload upregulated the expression of Bax, Caspase-3, Caspase-9, GRP78, GRP94, P-PERK, ATF4, eIF2 alpha, IRE1, and ATF6, while downregulating the expression of Bcl-2 and the PI3K/AKT/mTOR pathway. XBP-1 splicing experiment showed significant splicing of XBP-1 gene after iron overload. PCA and correlation analysis suggested a potential association between endoplasmic reticulum stress, the PI3K/AKT/mTOR signaling pathway, and liver injury in chicks. In summary, iron overload can induce cell apoptosis and liver injury by affecting endoplasmic reticulum stress and the PI3K/AKT/mTOR signaling pathway.