Histone lysine crotonylation accelerates ACSL4-mediated ferroptosis of keratinocytes via modulating autophagy in diabetic wound healing.

Dysfunction of keratinocytes affects diabetic wound healing, but underlying mechanisms have not been understood. This study examines crotonylation's role in ferroptosis and autophagy in keratinocytes, particularly regarding ACSL4, using STZ-induced diabetic rats and high glucose-exposed keratinocytes to assess these processes. The ACSL4 knockdown was achieved using adenovirus in wounds to examine the impact of ferroptosis modulation on healing diabetic wounds. MB-3 was utilized to block the H3K27 crotonylation (H3K27cr) in order to clarify the regulatory function of crotonylation in both autophagy and ferroptosis. In STZ-induced diabetic skin and high glucose-exposed keratinocytes, ferroptosis mediated by ACSL4 and suppression of autophagic flux were demonstrated. Moreover, the downregulation of ACSL4 triggered ferroptosis in adjacent wounds of diabetic rats and improved wound healing. The degradation of ACSL4 may be observed via the autophagy-lysosome pathway in keratinocytes. Downregulation of SQSTM1 in diabetic keratinocytes leads to autophagy inhibition and modulates the protein level of ACSL4. Mechanistically, total crotonylation levels and H3K27cr were remarkably elevated in the skin and keratinocytes of diabetic rats; blocking high glucose-induced H3K27cr with MB-3 can enhance SQSTM1 transcription and expression while promoting autophagy and reducing ACSL4-induced ferroptosis in keratinocytes. Therefore, H3K27cr influences autophagy by adjusting SQSTM1 to facilitate ACSL4-triggered ferroptosis in diabetic keratinocytes. This study clarifies the relationships between acylation modifications, autophagy, and ferroptosis, while also offering mechanistic insights and potential therapeutic targets for issues associated with diabetic wound healing.