UBOX5 Modulates the Cognitive Dysfunction by Degrading HSP70 Protein in Sleep-Deprived Mice.

Sleep deprivation is a global health concern that disrupts hippocampal proteostasis and leads to cognitive decline. Heat shock protein 70 (HSP70), a key molecular chaperone supporting neuronal survival, is downregulated under sleep deprivation, yet its regulatory mechanisms remain unclear. A murine sleep deprivation model was established using the multiple-platform method. Cognitive performance was assessed with the Y-maze and novel object recognition tests. Western blotting, qRT-PCR, cycloheximide (CHX) chase, and coimmunoprecipitation assays were performed to examine the regulation of HSP70 by the E3 ligase UBOX5. In vivo, mice with UBOX5 knockout were treated with sleep deprivation, followed by behavioral testing and enzyme-linked immunosorbent assay measurement of hippocampal cytokines. Sleep deprivation produced a duration-dependent decline in memory and recognition, accompanied by reduced hippocampal HSP70 and increased UBOX5 expression. In vitro, UBOX5 overexpression decreased, whereas knockdown increased HSP70 protein abundance without altering transcript levels. CHX chase assays confirmed accelerated degradation, and coimmunoprecipitation demonstrated UBOX5-dependent, UBE2M-mediated polyubiquitination of HSP70. Knockout of UBOX5 attenuated sleep deprivation-induced cognitive impairment and neuroinflammation. UBOX5 destabilizes HSP70 via ubiquitination, promoting sleep deprivation-induced neuroinflammation and cognitive dysfunction. These findings support the UBOX5/HSP70 axis as a novel mechanistic link between sleep deprivation and neuronal injury, and a potential therapeutic target.