ELAVL1-stabilized USP22 promotes diabetic nephropathy progression via mediating podocyte injury and death by...

Diabetic nephropathy (DN) represents approximately 50 % of all chronic kidney disease cases. Given the established involvement of USP22 in DN progression, this study investigated its underlying regulatory mechanisms.

Mouse podocytes were treated with high glucose (HG), and a diabetic mouse model was established. Podocyte viability and apoptosis were assessed by CCK-8 and TUNEL/flow cytometry, respectively. Ferroptosis markers (Fe²⁺, ROS, MDA, and GSH) and inflammatory cytokines were quantified using ELISA and commercial kits per manufacturers' protocols. The interaction of USP22 with ACSL4 was demonstrated through protein stability and co-immunoprecipitation (Co-IP) assays. Additionally, RNA immunoprecipitation (RIP) and mRNA stability assays were employed to elucidate the ELAVL1/USP22 interaction.

In HG-treated podocytes, USP22 silencing enhanced cell viability (P = 0.0018), repressed apoptosis (P = 0.0019), and reduced the release of inflammatory cytokines (IL-1β: P = 0.0002; TNF-α: P < 0.0001) and ferroptosis markers (Fe²⁺: P = 0.0002; ROS: P = 0.0005; MDA: P = 0.0017; GSH: P = 0.0086). Conversely, USP22 overexpression in HG-treated podocytes exhibited the opposite effects (P < 0.05). USP22 increased ACSL4 expression (P = 0.0012) in a deubiquitination-dependent manner. Notably, ACSL4 overexpression rescued USP22 depletion-mediated alterations on cell viability, apoptosis, inflammation, and ferroptosis (P < 0.05). Moreover, ELAVL1 stabilized USP22 mRNA through interaction (P = 0.0075). USP22 silencing alleviated DN progression and reduced inflammation cytokine secretion in a diabetic mouse model (P < 0.05).

ELAVL1-stabilized USP22 promotes DN progression by exacerbating podocyte injury and enhancing inflammatory responses and cell death through ACSL4 deubiquitination-dependent mechanisms.