DHHC15 and APT2-Regulated S-Palmitoylation of Hsp90α Promotes Hypoxia-Inducible Factor (HIF)-1α Stabilization in Tubular Epithelial Cells and Renal Fibrosis

Background: Metabolic reprogramming of renal tubular epithelial cells (TECs), particularly enhanced glycolysis regulated by Hif1α, plays a critical role in renal fibrosis. However, the mechanisms underlying the regulation of Hif1α stabilization in TECs remain unclear. Methods: Ischemic reperfusion injury (IRI) and repeated low-dose cisplatin injection (RLDC) models were employed to induce renal fibrosis in mice. Mouse models with renal tubule-specific knockout of ZDHHC15 were generated. Primary cultured tubular cells were treated with TGFβ1. The S-palmitoylation of Hsp90α was validated using acyl biotin exchange and protein acyltransferase assays. Results: We found that the expression of the palmitoyltransferase DHHC15 was significantly upregulated in the fibrotic kidneys of chronic kidney disease (CKD) patients and mouse models. Functionally, tubule-specific deletion of ZDHHC15 reduced extracellular matrix (ECM) production and alleviated renal fibrosis induced by IRI or RLDC. Mechanistically, ZDHHC15 catalyzed the palmitoylation of Hsp90α, which is crucial for its binding with client proteins. Palmitoylation of Hsp90α at Cys573 inhibited Hif1α ubiquitination, thereby enhancing its stabilization and nuclear translocation, which promoted glucose uptake and lactate production in TECs. Additionally, APT2 levels were reduced in the fibrotic kidneys. APT2 could depalmitoylate Hsp90α, impairing Hif1α stabilization and nuclear translocation. Ablation of tubular APT2 or inhibition with ML349 significantly aggravated IRI or RLDC-induced renal fibrosis in mice. Conclusion: This study demonstrates that DHHC15 and APT2 may regulate Hif1α palmitoylation and play a crucial role in renal fibrosis. Funding: Government Support – Non-U.S.