Human ATF4 adenoviral particles

Ferroptosis is a regulated form of cell death characterized by lipid peroxidation and iron accumulation, and its role in disease pathogenesis is increasingly appreciated. The unfolded protein response (UPR) is associated with endoplasmic reticulum (ER) stress and ferroptosis-mediated cell fate decisions. However, the specific mechanisms remain unclear. In this study, researchers demonstrated that both tunicamycin-induced ER stress and erastin-triggered ferroptosis activate the UPR, thereby inducing ferroptosis. This cell death can be alleviated by the use of chemical chaperones and ferroptosis inhibitors. Among the three branches of the UPR, the PERK-eIF2α-ATF4 signaling axis was identified as a key mediator in this process. Mechanistically, ATF4-driven DDIT4 induction plays a key role, promoting ferroptosis by inhibiting the mTORC1 pathway. In addition, acetaminophen (APAP)-induced hepatotoxicity was studied as a model of eIF2α-ATF4-mediated ferroptosis. These findings suggest that inhibition of eIF2α-ATF4 or ferroptosis protects against APAP-induced liver injury, highlighting the therapeutic potential of targeting these pathways. Overall, this study not only elucidates the complex role of the PERK-eIF2α-ATF4 axis in ER stress and erastin-induced ferroptosis, but also extends these findings to clinically relevant models, laying the foundation for potential therapeutic interventions in diseases characterized by dysregulated ferroptosis and ER stress.

To investigate the role of ATF4 in ferroptosis, researchers used adenovirus to overexpress ATF4 (Ad-ATF4), which resulted in increased cell death and elevated Ptgs2 expression and lipid peroxidation levels after erastin treatment compared to control virus expressing GFP (Ad-GFP) (Figure 1F-H). Ad-ATF4 significantly altered the expression of ferroptosis-related proteins and MDA levels after erastin treatment compared to cells infected with Ad-GFP (Figure 1I). In subsequent experiments, ATF4 was reintroduced into Atf4−/− cells, which had previously shown resistance to erastin-induced ferroptosis. Unlike cells infected with Ad-GFP, Atf4−/− cells infected with Ad-ATF4 showed a marked increase in sensitivity to ferroptosis, comparable to Atf4+/+ cells (Figure 1J). These cells also showed enhanced responsiveness to the erastin-triggered ferroptosis pathway, exhibiting elevated Ptgs2 mRNA levels, increased lipid peroxidation, and altered GPX4, CHAC1, and DDIT4 protein expression and MDA levels after erastin treatment, similar to Atf4+/+ cells (Figure 1K-M). These results suggest that ATF4 is involved in the activation of ferroptosis signaling and may potentially contribute to ferroptosis-mediated cell death.

Figure 1. ATF4 is an important transcription factor for erastin-induced ferroptotic pathway. (Nghiem T H T, et al., 2025)