HNRNPC Succinylation Influences the Neurodegeneration of Alzheimer's Disease Through YME1L1 ‐Mediated Mitochondrial Metabolism

ABSTRACT

Mitochondrial dysfunction and abnormal energy metabolism are important pathological features of Alzheimer's disease (AD). This study investigates how mitochondrial protease YME1L1 affects mitochondrial function and its upstream regulation in the pathogenesis of AD. The AD model was established by using APP/PS1 transgenic mice, primary neurons treated with Aβ1‐42, and HT22 cells. The silencing of YME1L1 was achieved to evaluate its effects on mitochondrial function and OPA1 protein hydrolysis. RIP‐qPCR and RNA pull‐down test were used to evaluate the interaction between HNRNPC and YME1L1 mRNA. The protein succinylation level was detected by proteomic analysis of succinylation, and co‐immunoprecipitation (Co‐IP) was used to verify the succinylation of HNRNPC. Cognitive ability was tested by behavioral tests, including the Morris water maze, Y‐maze, object recognition test, and olfactory test. Finally, the therapeutic potential of SIRT5 was studied by an overexpression experiment in an AD model. YME1L1 was significantly upregulated in the AD model, which promoted mitochondrial dysfunction and neuronal damage through OPA1 hydrolysis. HNRNPC enhances the stability of YME1L1 mRNA through an m6A‐dependent mechanism, while its own K50 succinylation enhances the stability of HNRNPC by competitively inhibiting TRIM25‐mediated ubiquitination, further amplifying the expression of YME1L1. SIRT5 downregulation in AD elevated HNRNPC succinylation levels. SIRT5 overexpression promoted HNRNPC desuccinylation, reduced YME1L1 expression, restored mitochondrial function, and ameliorated Aβ deposition and cognitive deficits in AD mice. The SIRT5‐HNRNPC‐YME1L1 axis contributes to AD pathogenesis by disrupting OPA1 proteolysis and mitochondrial dynamics. Targeting HNRNPC succinylation represents a promising therapeutic strategy for AD.