The effect of TSPO transmembrane transport-mediated paeonol mitochondrial antioxidant on dexamethasone-induced mitochondrial abnormalities, oxidative stress damage, and apoptosis in SV40-MES-13 cells

Abstract

Dexamethasone (DEX) can induce pathological kidney injury but is still a first-line therapeutic agent; thus, elucidating the mechanism of DEX-induced kidney injury and developing targeted therapies to mitigate its effects are imperative. The aim of this study was to elucidate the mitochondrial targeting mechanism of the natural plant compound paeonol on DEX-induced mesangial cell injury. To achieve this, we employed RT q-PCR and Western blot analyses to quantify gene/protein expression, flow cytometry for apoptosis assessment (Annexin V/PI staining) and mtROS detection (MitoSOX Red), JC-1 probe for mitochondrial membrane potential (ΔΨm) measurement, and High-sensitivity structured illumination microscopy (HiS-SIM) imaging for ultrastructural analysis. ATP synthesis assays and malondialdehyde (MDA) quantification were used to evaluate mitochondrial function and lipid peroxidation, respectively, while Mn-SOD activity was determined via enzymatic assays. Paeonol counteracted these effects via four mechanisms: restoration of mitochondrial ultrastructure. reactivation of MRCC IV activity, reduction of mtROS and malondialdehyde, and enhancement of manganese superoxide dismutase antioxidant capacity. Crucially, paeonol used the mitochondrial entry mechanism mediated by the translocater protein (TSPO). By blocking the oxidative stress-apoptosis cascade, downregulating BAX, preserving BCL-2, and inhibiting cytochrome c efflux, the early/late apoptotic population was significantly reduced. This study confirmed that TSPO-mediated intra-mitochondrial antioxidant paeonol alleviates DX-induced mitochondrial dysfunction, oxidative stress, and apoptosis in SV40-MES-13 cells.