Serum response factor aggravates acute kidney injury via the NIK/NF-κB signaling in LPS-treated HK-2 cells.

Sepsis, a life-threatening systemic inflammatory response syndrome mediated by dysregulated host-pathogen interactions, frequently precipitates in renal injury. Renal tubular epithelial cell (RTEC) injury is a hallmark of septic acute kidney injury (AKI). Recent studies have demonstrated the involvement of serum response factor (SRF) in septic AKI. Herein, the role and mechanism of SRF as a transcription factor in regulating RTEC dysfunction were explored. HK-2 cells (the human RTEC line) were treated with lipopolysaccharide (LPS) for the establishment of in vitro septic AKI models. HK-2 cell viability was validated using CCK-8 assay. HK-2 cell apoptosis was evaluated by flow cytometry analysis. Measurement of proinflammatory cytokine concentration was conducted using enzyme-linked immunosorbent assay kits. RT-qPCR were required for determining gene levels. Western blotting was prepared for testing the protein levels of proinflammatory cytokines, apoptosis-related markers, NF-κB p65 and NF-κB inducing kinase (NIK). The binding of SRF to NIK promoter was confirmed by chromatin immunoprecipitation and luciferase reporter assays. LPS treatment suppressed HK-2 cell viability and accelerated HK-2 cell inflammation and apoptosis, which was antagonized by SRF depletion. Mechanically, SRF as a transcription factor bound to NIK promoter. SRF silencing inhibited LPS-induced NF-κB signaling activation in HK-2 cells. In rescue assays, NIK overexpression counteracted the restrictive impact of SRF deficiency on LPS-induced HK-2 cell dysfunction. SRF aggravates LPS-elicited HK-2 cell injury via binding to NIK promoter and activating NF-κB signaling. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10616-025-00854-z.