Copper-dependent redox remodeling of the actin cytoskeleton regulates renal epithelial cell mechanics

Copper is essential for cellular function but can become toxic in excess. Although its redox and enzymatic roles are well established, how copper availability affects cytoskeletal organization and cell mechanics remains unclear. Here, we show that elevated copper availability increases membrane tether force and F-actin anisotropy in HK-2 proximal tubule cells, consistent with actin cytoskeletal remodeling. Cotreatment with the membrane-permeable reactive oxygen species (ROS) scavenger Tiron reversed copper-induced ROS accumulation and mechanical changes without affecting cell viability, supporting a ROS-dependent mechanism. Quantitative proteomics and post-translational modification profiling (ProteomeXchange: PXD072220) identified coordinated changes in actin-regulatory proteins, including Rab35, methionine sulfoxide reductase B2, casein kinase 2 subunits, and Septin2, together with reduced actin methionine oxidation and copper-sensitive phosphorylation shifts. These findings identify copper-driven redox signaling as a modulator of renal epithelial cell mechanics associated with remodeling of actin-regulatory pathways.NEW & NOTEWORTHY Copper-driven redox signaling remodels the actin cytoskeleton and reprograms the mechanical properties of renal proximal tubule cells. Using optical tweezers, fluorescence imaging, quantitative proteomics, and PTM profiling, we link ROS-dependent mechanical changes to coordinated remodeling of the Rab35/MICAL1/MsrB2 and CK2/Septin2 regulatory axes, establishing copper availability as a modulator of renal epithelial cell mechanics with potential relevance to copper dyshomeostasis in kidney injury.