HDAC5 deacetylates cytosolic ACTN4 during skin reepithelialization and represents a therapeutic target for chronic wound healing

Skin repair after injury is a complex multistage process. Reepithelialization is a vital component of skin wound healing and involves intricate molecular regulations that are still not fully understood. Here, using a combination of human tissue and animal models, we identified histone deacetylase 5 (HDAC5) as a key mediator of reepithelialization through a mechanism involving nucleocytoplasmic shuttling to regulate deacetylation of a nonhistone protein. We conducted functional validation through a conditional gene knockout mouse model. In addition, parallel studies using ex vivo human skin confirmed that HDAC5 cytoplasmic localization is necessary for efficient wound closure. Liquid chromatography-mass spectrometry of mouse wounds revealed that cytoplasmic HDAC5 interacts with alpha-actinin-4 (ACTN4). Site-directed mutagenesis, immunofluorescence, and luciferase assays demonstrated that HDAC5 deacetylates ACTN4 at the K417 site, allowing nuclear translocation of ACTN4 and subsequent modulation of transcriptional activity of Y-box-binding protein 1 (YBX1). Single-cell transcriptome analysis of mouse wounds revealed Cystatin A as a key factor downstream of the HDAC5/ACTN4/YBX1 axis that enhanced reepithelialization and wound healing. We further identified an HDAC5-selective activator, G194-0712, and showed that it improved wound healing in three mouse models of chronic wounds: diabetic wounds, ischemic wounds, and radiation injury. Together, these results highlight a previously unappreciated mechanism involved in skin repair and suggest that HDAC5 activation may hold promise for the treatment of nonhealing skin wounds.