Background: Acute kidney injury (AKI) is clinically characterized by a rapid deterioration of renal function and is often associated with inflammation and oxidative stress. This study elucidated protective roles and underlying mechanisms of tight junction (TJ) proteins in AKI, with particular emphasis on the involvement of the TYRO protein tyrosine kinase binding protein (TYROBP) (also known as DNAX-associated protein 12 [DAP12])/phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway.

Methods: After establishing a cisplatin-induced AKI model, TJ protein levels, inflammation and oxidative stress were evaluated. ZO-1 (TJP1)-related genes were identified using Weighted Gene Co-Expression Network Analysis (WGCNA) and Protein-Protein Interaction (PPI) network analysis. An HK-2 cell injury model was established using cisplatin, followed by assessment of the impact of DAP12 silencing on TJ proteins, inflammation, oxidative stress, and PI3K/AKT signaling pathway. Renal function, inflammation (tumor necrosis factor-α [TNF-α] and interleukin-1β [IL-1β]), oxidative stress (reactive oxygen species [ROS] and malondialdehyde [MDA]), and TJ protein levels were determined through histopathology, Western blotting and enzyme-linked immunosorbent assay (ELISA).

Results: Cisplatin-induced AKI resulted in downregulated TJ proteins (ZO-1, Occludin, Claudin-1), elevated inflammation and oxidative stress, and activated DAP12/PI3K/AKT (p < 0.05). Among the three TJ proteins, only TJP1 level was diminished in kidney injury-related diseases. Then, through WGCNA and PPI analysis, DAP12 was identified as a key gene negatively correlated with TJP1. DAP12 silencing in the HK-2 cell injury model attenuated cellular damage, restored TJ protein expression, and reduced inflammation and oxidative stress, concomitantly suppressing the activation of the PI3K/AKT pathway (p < 0.01).

Conclusion: Targeting the DAP12/PI3K/AKT pathway and TJ proteins presents therapeutic potential for AKI, and the upstream and downstream mechanisms of DAP12 in kidney injury warrant further investigation.