STAP2 promotes the progression of renal fibrosis via HSP27

Renal fibrosis is a key process in the progression from acute kidney injury (AKI) to chronic kidney disease (CKD), while the intricate mechanisms of renal fibrosis remain obscure. While the signal-transducing adaptor protein 2 (STAP2) was well-studied for its notable function in inflammation and immune-related disorders, its specific implication in renal fibrosis remains unclear. This study assessed the mechanism by which STAP2 could promote the progression of renal fibrosis. The expression level of STAP2 in fibrotic human samples, murine fibrosis models, and cellular fibrosis models was measured, respectively. Subsequently, immunoprecipitation (IP), mass spectrometry, and RNA sequencing (RNA-seq) were employed to identify HSP27 as an interacting protein and the PI3K-AKT signaling pathway. STAP2 was thereafter knocked down or overexpressed in both in vivo and in vitro models to assess the expression levels of pathway-related and fibrosis-related proteins. Finally, the important role of STAP2 in the fibrosis process in animal models induced by ischemia-reperfusion injury (IRI) and cisplatin was validated. Functionally, in vivo assays demonstrated that the genetic knockout of STAP2 could remarkably mitigate epithelial-mesenchymal transition (EMT), diminish inflammatory cell infiltration, and reduce collagen deposition in mice with renal fibrosis. Conversely, in vitro assays employing STAP2-overexpressing cell models exacerbated the expression levels of fibrosis markers. The outcomes uncovered a potential mechanism by which STAP2 could modulate renal fibrosis through its impact on the expression level of phosphorylated HSP27, as well as modulating the PI3K/AKT signaling pathway. This comprehensive investigation delineated the noticeable function of STAP2 in the advancement of renal fibrosis, and the outcomes might contribute to the development of targeted therapies concentrated on STAP2 to mitigate renal fibrosis.