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Updated: Oct 10, 2026

Cell-Based Drug Screening for Inhibitors of Autophagy Related 4B Cysteine Peptidase
Published on: June 30, 2023
Disrupting BRD4-BD1-p62 engagement restores protective autophagy
Jifa Zhang1, Yu Cao1, Chengyong Wu1
1Department of Biotherapy, State Key Laboratory of Biotherapy and Cancer Center, Laboratory of Neuro-system and Multimorbidity, Department of Respiratory and Critical Care Medicine, Center for High Altitude Medicine, Children's Medicine Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, Chengdu 610041, Sichuan, P.R. China.
Abstract:
Impaired protective autophagy contributes to idiopathic pulmonary fibrosis (IPF), yet therapeutic strategies that restore this process remain limited. Here, we identify SKLB-39b, a BRD4-BD1-selective inhibitor that restores protective autophagy and attenuates pulmonary fibrosis. SKLB-39b exhibits over 100-fold selectivity for BRD4-BD1 relative to BRD4-BD2 and nearly 10-fold greater affinity for BRD4-BD1 than for BRD2/3-BD1. Mechanistically, we identify a BRD4-BD1-p62 interaction that links BET bromodomain function to autophagy regulation. By engaging Leu92 and Ile146 through a hydrophobic binding mode, SKLB-39b disrupts this interaction, restores ULK1-dependent autophagy, and provides a structural framework for BD1-selective inhibitor design. SKLB-39b outperformed JQ-1 in suppressing fibroblast activation, epithelial-mesenchymal transition, and collagen deposition in experimental fibrosis while showing favorable pharmacokinetic exposure and no overt toxicity in the mouse studies performed. These findings establish the BRD4-BD1-p62 interface as a druggable target for restoring protective autophagy in IPF.
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