RNF5 promotes acute lung injury through HSPA5 ER-to-cytosol translocation and resultant PERK activation.

Authors

Ya-Zhou Sun, Xin-Yan Li, Jia Wang, Meng-Liu Zeng, Wei-Yi Qu, Xu Cheng, Lei Luo, Wei Wang, Juan Yang, Jun Zhang, Han Tian, Peng Zhang, Zhi-Gang She, Hongliang Li, Xiao-Jing Zhang

Published in

Cell death and differentiation. Aug 10, 2026. Epub Aug 10, 2026.

Abstract

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe conditions lacking specific pharmacological treatments. Endoplasmic reticulum (ER) stress plays a pivotal role in their pathophysiology, yet the precise regulatory mechanisms remain elusive. In this study, we identify the E3 ubiquitin ligase ring finger protein 5 (RNF5) as a critical driver of ALI/ARDS. RNF5 is markedly upregulated in response to ALI and significantly exacerbates lung injury by stabilizing HSPA5 (heat shock protein family A member 5), a master regulator of the unfolded protein response (UPR). Notably, in vivo Rnf5 ablation effectively attenuated pulmonary edema, inflammatory cell infiltration, and apoptosis, whereas lung-specific Rnf5 overexpression worsened inflammation and cell death in mice. Mechanistically, RNF5 interacts with HSPA5 and competitively blocks its binding to PERK, facilitating PERK release. Furthermore, RNF5 promotes the retro-translocation of HSPA5 from the ER lumen to the cytosol. In the cytosol, RNF5 mediates the K6- and K63-linked polyubiquitination of HSPA5, enhancing its thermal stability and preventing its re-entry into the ER. This spatial sequestration sustains the persistent dissociation of the PERK-HSPA5 complex, leading to the hyperactivation of the pro-apoptotic and pro-inflammatory PERK-eIF2α-CHOP signaling cascade. The ability of RNF5 to promote ALI is strictly dependent on its E3 ligase activity. In conclusion, our findings uncover a compartment-specific regulatory mechanism of HSPA5, suggesting that the RNF5-HSPA5-PERK axis represents a promising therapeutic target for ALI/ARDS.

PMID:
42575990
Bibliographic data and abstract were imported from PubMed on 11 Aug 2026.

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