HDAC8-mediated CAPZB desuccinylation enhances cytoskeleton remodeling to promote idiopathic pulmonary fibrosis

Background Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrosing interstitial pneumonia of unknown etiology. Abnormal regulation of the cytoskeleton is a key factor driving pulmonary fibrogenesis. However, the molecular mechanisms of cytoskeleton remodeling in pulmonary fibrosis remains obscure. Methods Succinylome analysis of lung tissues from bleomycin (BLM)-treated mice was performed. Key modified proteins and sites were identified through Clusters of Orthologous Groups (COG) functional classification statistics and liquid chromatograph-mass spectrometer (LC-MS/MS) analysis. F-actin-capping protein subunit beta (CAPZB) was selected for further investigation. Gain- and loss-of-function and modified site mutation studies were conducted to assess the function of CAPZB in pulmonary fibrosis and the effect of succinylation on it. Then, Co-immunoprecipitation (Co-IP) and functional studies were used to identify the desuccinylase for CAPZB. Finally, adenoviral vectors were constructed to evaluate the effect of CAPZB on pulmonary fibrosis in vivo. Results A total of 910 lysine succinylation sites in 388 proteins were differentially expressed between the BLM-treated mice and the sham group. COG functional classification statistics showed that 42 proteins were classified into cytoskeleton-related proteins. Among these proteins, the succinylation level of CAPZB was significantly decreased. And lysine57 (K57), lysine95 (K95), and lysine235 (K235) were identified as the desuccinylation sites of CAPZB in pulmonary fibrosis. Gain- and loss-of-function studies revealed that CAPZB restrained cytoskeletal remodeling to inhibit pulmonary fibrogenesis. The effect of succinylation modification on CAPZB function revealed that CAPZB desuccinylation inhibited its capping function on the barbed end of F-actin, resulting in promote fibroblast proliferation, migration, and differentiation. Further, histone deacetylase enzymes (HDACs) inhibitors and Co-IP demonstrated that HDAC8 is the desuccinylase for CAPZB in pulmonary fibrosis. Overexpressed HDAC8 desuccinylated CAPZB, led to abnormal F-actin polymerization and promoted pulmonary fibrosis. Finally, the therapeutic effect of succinylated CAPZB was confirmed in mice. Conclusions Collectively, our research revealed that HDAC8-mediated CAPZB desuccinylation promoted idiopathic pulmonary fibrosis by enhancing cytoskeleton remodeling, suggesting that desuccinylated CAPZB could be a potential therapeutic target related to cytoskeleton remodeling for pulmonary fibrosis.