USP15 promotes brain cell disulfidptosis in mouse subjected to ischemic stroke through a mechanism involving deubiquitination of SETD1B.

Disulfidptosis due to excessive accumulation of disulfides is a novel form of regulated cell death. Whether disulfidptosis occurs in ischemic stroke and the underlying mechanisms remain elusive. RNA transcriptomics sequencing (RNA-seq) reveales that knockdown of SET domain containing 1B (SETD1B), a histone lysine methyltransferase, decreases the expression of disulfidptosis-related genes. Using Ubibrowser database, Ubiquitin-specific protease 15 (USP15) is predicted to be a deubiquitinase (DUB) for SETD1B. This study investigates whether SETD1B promote disulfidptosis in ischemic stroke via upregulating disulfidptosis-related genes and whether USP15 deubiquitinates SETD1B. A C57BL/6 J mouse model of ischemic stroke was established, which results in brain injury and upregulation of USP15 and SETD1B, concomitant with the increased disulfidptosis, as indicated by the increased level of NADP/NADPH ratio, elevated protein levels of NCK associated protein 1 like (NCKAP1L) and WASP family protein member 2 (WAVE-2), disulfide bond accumulation, and cytoskeleton detachment from the cytoplasmic membrane. Similar results were observed in cultured HT22 cells subjected to oxygen-glucose deprivation plus reoxygenation (OGD/R), and USP15 or SETD1B siRNAs reversed these phenomena. Mechanistically, knockdown of SETD1B prevented H3K4me3 enrichment at the Nckap1l and Wasf2 promoters and reduced Nckap1l and Wasf2 expression. Moreover, knockdown of USP15 increased the ubiquitination level of SETD1B thus decreasing its protein level. Based on these findings, we concluded that SETD1B can promote disulfidptosis in stroke brain cells via a mechanism involving facilitating H3K4me3 enrichment at the Nckap1l and Wasf2 promoters, while USP15 is able to deubiquitinate SETD1B and increase SETD1B level in ischemic stroke mice.