The role of TOMM20 in Mediating TERT translocation to mitochondria and its impact on mitophagy in membranous nephropathy

In idiopathic membranous nephropathy (MN)—now a leading glomerular cause of end-stage kidney disease—mitochondrial quality control via mitophagy is increasingly recognized as a determinant of podocyte fate, yet the molecular switches governing this process remain undefined. We postulated that translocase of the outer mitochondrial membrane 20 (TOMM20), a gatekeeper of mitochondrial import, transcriptionally regulates telomerase reverse transcriptase (TERT) and thereby modulates podocyte mitophagy and disease progression. Bioinformatics analysis was performed to identify common targets between mitophagy-related genes and differentially expressed genes in membranous nephropathy. An in vitro model of membranous nephropathy was established by treating human podocytes with Zymosan-Activated Serum (ZAS). Subsequently, cells were transfected to overexpress TOMM20 or knock down TERT. Cellular viability, apoptosis, and levels of inflammatory cytokines (IL-6, IL-1β) were assessed. Additionally, indicators related to mitophagy, including reactive oxygen species (ROS), mitochondrial membrane potential (MMP), LC3-II/I ratio, PTEN-induced putative kinase 1 (PINK1), Mitochondrial-associated Parkin protein (mito-Parkin), and p62 levels, were measured in each group. An in vivo model of membranous nephropathy was established by intravenously injecting rats with sheep anti-rat FX1A serum. The expression of TOMM20 was inhibited to investigate its effects on mitophagy and TERT mitochondrial translocation in membranous nephropathy. Bioinformatics analysis identified TOMM20 as a key target for intervening in the progression of membranous nephropathy via the mitochondrial pathway. In vitro, compared with human podocytes treated with heat-inactivated serum (HIS), ZAS intervention resulted in decreased cell viability, increased apoptosis, elevated levels of IL-6, IL-1β, and ROS, reduced MMP, decreased LC3-II/I ratio, PINK1, and mito-Parkin, and enhanced p62 expression. Overexpression of TOMM20 ameliorated ZAS-induced cell injury and enhanced mitophagy. Additionally, compared with the ZAS + Ctrl-siRNA group, knockdown of TERT exacerbated ZAS-induced cell injury and inhibited mitophagy. However, co-overexpression of TOMM20 promoted TERT mitochondrial translocation and mitigated the adverse effects of TERT-siRNA transfection in human podocytes. In vivo, upregulation of TOMM20 improved renal function in rats, promoted TERT mitochondrial translocation, and activated mitophagy. TOMM20 activates mitophagy in membranous nephropathy by promoting the mitochondrial translocation and expression of TERT (The graphical abstract was shown in Fig. 1).