BACH1 promotes intervertebral disc degeneration by regulating HMOX1/GPX4 to mediate oxidative stress, ferroptosis, and lipid metabolism in nucleus pulposus cells

Abstract

Background: Intervertebral disc degeneration (IDD) is a primary health problem worldwide that involves oxidative stress, ferroptosis, and lipid metabolism. However, the underlying mechanism remains unclear. We investigated whether the transcription factor BTB and CNC homology 1 (BACH1) affected IDD progression by regulating HMOX1/GPX4-mediated ferroptosis and lipid metabolism in nucleus pulposus cells (NPCs).

Methods: A rat IDD model was created to detect BACH1 expression in intervertebral disc tissues. Next, rat NPCs were isolated and treated with tert-butyl hydroperoxide (TBHP). BACH1, HMOX1, and GPX4 were knocked down, and oxidative stress and ferroptosis-related marker levels were examined. The binding of BACH1 to HMOX1 and of BACH1 to GPX4 was verified using chromatin immunoprecipitation (ChIP). Finally, untargeted lipid metabolism analysis was performed.

Results: An IDD model was successfully created, and BACH1 activity was found to be enhanced in the rat IDD tissues. BACH1 inhibited TBHP-induced oxidative stress and oxidative stress-induced ferroptosis in NPCs. Simultaneously, ChIP verified that BACH1 protein bound to HMOX1 and targeted the HMOX1 transcription inhibition to affect oxidative stress in NPCs. ChIP also verified that BACH1 bound to GPX4 and targeted the GPX4 inhibition to affect ferroptosis in NPCs. Finally, BACH1 inhibition in vivo improved IDD and affected lipid metabolism.

Conclusions: The transcription factor BACH1 promoted IDD by regulating HMOX1/GPX4 to mediate oxidative stress, ferroptosis, and lipid metabolism in NPCs.

Keywords: BACH1; GPX4; HMOX1; ferroptosis; intervertebral disc degeneration; lipid metabolism.