Mitochondrial DNA deletion-dependent podocyte injuries in Mito-mice Delta, a murine model of mitochondrial disease

Focal segmental glomerulosclerosis (FSGS) is a major renal complication of human mitochondrial disease. However, its pathogenesis has not been fully explained. In this study, we focused on the glomerular injury of mito-mice Delta and investigated the pathogenesis of their renal involvement. We analyzed biochemical data and histology in mito-mice Delta. The proteinuria began to show in some mito-mice Delta with around 80% of mitochondrial DNA deletion, then proteinuria developed dependent with higher mitochondrial DNA deletion, more than 90% deletion. Mito-mice Delta with proteinuria histologically revealed FSGS. Immunohistochemistry demonstrated extensive distal tubular casts due to abundant glomerular proteinuria. Additionally, the loss of podocyte-related protein and podocyte's number were found. Therefore, the podocyte injuries and its depletion had a temporal relationship with the development of proteinuria. This study suggested mitochondrial DNA deletion-dependent podocyte injuries as the pathogenesis of renal involvement in mito-mice Delta. The podocytes are the main target of mitochondrial dysfunction originated from the accumulation of mitochondrial DNA abnormality in the kidney.