# BACH1–CHAC1–Glutathione Axis Aggravates Myocardial Ischemia–Reperfusion Injury by Enhancing Ferroptosis and Oxidative Stress

## TL;DR

The study identifies a new pathway involving BACH1 and CHAC1 that worsens heart damage during reperfusion by increasing oxidative stress and a type of cell death called ferroptosis.

## Contribution

The novel contribution is the discovery of the BACH1–CHAC1–GSH axis as a key upstream regulator of ferroptosis in myocardial ischemia–reperfusion injury.

## Key findings

- CHAC1 overexpression increases ferroptosis and myocardial injury by depleting glutathione and suppressing GPX4.
- BACH1 activates CHAC1, linking it to ferroptosis and oxidative stress in heart tissue.
- Inhibiting BACH1 or CHAC1, or supplementing GSH precursors, reduces injury in ischemia–reperfusion models.

## Abstract

Myocardial ischemia–reperfusion injury (MIRI) is a pathological process in which reperfusion-induced oxidative stress and metabolic derangement further aggravate myocardial damage and blunt the benefit of reperfusion. Ferroptosis is increasingly implicated in MIRI, with the glutathione (GSH)–glutathione peroxidase 4 (GPX4) axis constituting a key antioxidant barrier. Although GSH depletion is recognized as a critical event, its upstream regulation in MIRI remains unclear. Against this background, we investigate the BACH1–CHAC1–GSH pathway as a putative upstream regulatory axis of ferroptosis in MIRI and a potential molecular target. Here, using an oxygen–glucose deprivation/reoxygenation (OGD/R) model in AC16 and the reversibility conferred by the ferrostatin-1, RNA sequencing identified the GSH-degrading enzyme CHAC1 as a modulator that is induced by stress and promotes ferroptosis. Experiments showed that CHAC1 overexpression aggravated OGD/R-induced injury, depleted GSH, suppressed GPX4 and enhanced lipid peroxidation, whereas CHAC1 knockdown was partially protective. N-acetylcysteine (NAC) replenished GSH, restored GPX4 activity and partially rescued CHAC1-driven injury. In a mouse myocardial I/R model, cardiotropic adeno-associated virus-mediated CHAC1 overexpression worsened cardiac dysfunction, enlarged infarct and fibrosis areas, and increased myocardial iron deposition. Dual-luciferase assays revealed that the transcription factor BACH1 activates the CHAC1 promoter, and BACH1 silencing attenuated ferroptosis by suppressing CHAC1 and restoring the GSH–GPX4 axis. Collectively, our data identify the BACH1–CHAC1–GSH axis as an upstream amplifier of ferroptosis in MIRI through glutathione depletion and impairment of GPX4-dependent antioxidant defense. These findings refine the mechanistic link between reperfusion-phase redox imbalance and ferroptosis and highlight BACH1/CHAC1 inhibition or augmentation of GSH precursors as potential cardioprotective strategies in ischemic heart disease.