SETDB1 recruits CBX3 to regulate the SIRT4/PTEN axis, inhibiting autophagy and promoting ischemia-reperfusion-induced kidney injury.

Ischemia-reperfusion (I/R) injury is a significant factor in the development of acute kidney injury (AKI), particularly in clinical scenarios, such as kidney transplantation, cardiac surgery, and severe hypotension. Autophagy, a critical process that eliminates damaged cellular components, has been shown to mitigate I/R injury by reducing oxidative stress and enhancing cell survival. However, when autophagy is disrupted, it can exacerbate kidney damage. Elucidating the role of autophagy in I/R injury is essential for uncovering the molecular mechanisms driving AKI and could facilitate the development of autophagy-based therapies. Protein expression levels were analyzed through western blot, immunohistochemistry (IHC), and immunofluorescence (IF) staining techniques. Interactions between SIRT4, SETDB1, and CBX3 were explored using chromatin immunoprecipitation (ChIP), sequential ChIP (ChIP-reChIP), and co-immunoprecipitation (Co-IP) assays. The association between SIRT4 and PTEN was also examined via Co-IP. Transmission electron microscopy (TEM) was employed to visualize autophagosomes. Furthermore, an in vivo rat model of I/R injury was developed for validation of the findings. Sirtuin 4 (SIRT4) expression was reduced, and autophagy was impaired during I/R injury. Moreover, SIRT4 interacted with phosphatase and tensin homolog (PTEN) to regulate its expression. Furthermore, SET domain bifurcated histone lysine methyltransferase 1 (SETDB1) mediated histone H3 lysine 9 trimethylation (H3K9me3) modifications and recruited chromobox protein homolog 3 (CBX3) to the SIRT4 promoter, leading to the repression of SIRT4 expression in kidney proximal tubular cells. Importantly, SETDB1 knockdown upregulated SIRT4, decreased PTEN expression, promoted autophagy, and protected rats against I/R injury in vivo. SETDB1 recruits CBX3 to regulate the SIRT4/PTEN axis, inhibiting autophagy and promoting I/R-induced kidney injury. These results suggest that targeting the SETDB1-SIRT4 axis could offer a novel therapeutic strategy to mitigate renal damage in I/R-induced AKI.