Rab7-regulated ferroptosis contributes to tubular epithelial cells injury by degradation of GPX4 via chaperone-mediated autophagy in AKI.

Evidence suggests that the progression of acute kidney injury (AKI) is driven by tubular epithelial cell (TEC) injury. However, the role of ferroptosis during the regulatory process remains unclear. Fifty-three patients with AKI were included to examine the expressions of Rab7, glutathione peroxidase 4 (GPX4), and Hif-1α by immunohistochemistry. The relationship between these expressions and serum creatinine (Scr) and blood urea nitrogen (BUN) levels was analyzed. After inducing AKI and ferroptosis through bilateral renal artery ischemia-reperfusion injury (I/R) in vivo and hypoxia in vitro, we examined the expression of Rab7. The injury and ferroptosis were observed following the administration of erastin or ferrostatin-1 (Fer-1), as well as the downregulation of Rab7. In addition, we investigated the degradation of GPX4 and chaperone-mediated autophagy (CMA). Finally, we assessed the injury and ferroptosis after the combination of RAS-selective lethal 3 (RSL3) and downregulation of Rab7. GPX4 exhibited an inverse correlation with Hif-1α, Scr, BUN, and Rab7. Conversely, Rab7 was positively correlated with Scr and BUN. Both in vivo and in vitro models resulted in elevated levels of ferroptosis and Rab7. Erastin exacerbated ferroptosis and injury, but this effect was mitigated by Fer-1. Downregulation of Rab7 reversed the increased ferroptosis and injury. Hypoxia enhanced lysosomal transport and degradation of GPX4 through activation of CMA. Furthermore, the reversal of these effects was observed upon the downregulation of Rab7. However, the results obtained from Rab7 downregulation were subsequently reversed by RSL3. Ferroptosis is important in TEC injury during AKI and Rab7 promotes tubular ferroptosis by facilitating CMA-mediated degradation of GPX4. To explore the mechanism underlying ferroptosis in I/R-induced renal injury and to confirm the effect of Rab7, we first evaluated ferroptosis in renal biopsy samples, and then examined Rab7 expression and renal tubular injury during AKI in vivo and in vitro. Finally, we performed in vitro experiments to investigate the specific role of Rab7 in the regulation of ferroptosis and showed that the regulatory mechanism was related to CMA-mediated GPX4 degradation in renal TECs.