Overproduction of Mitochondrial Fission Proteins in Membranous Nephropathy in Children

Background/Aims: The molecules involved in nephrotic syndrome (NS) have not been fully clarified. Mitochondrial fission proteins are found to be involved in podocyte injury in vitro. Increased glomerular expression of mitochondrial fission proteins was found in adriamycin nephropathy in our previous study. Whether or not mitochondrial fission proteins are involved in podocyte injury in NS is not clear. This study explored the glomerular expression and possible pathological significance of mitochondrial fission-associated proteins, including dynamin-related protein 1 (Drp1) and mitochondrial fission protein 1 (Fis1), in children with NS. Methods: Eighteen children with primary NS, including 6 with minimal change disease, 6 with focal segmental glomerulosclerosis, 6 with membranous nephropathy, 6 children with isolated haematuria and 3 normal controls were included. The glomerular expression of Drp1, phospho-Drp1 (Ser616) and Fis1, urinary protein measurements, and podocyte mitochondrial density under electron microscopy were investigated and compared. Results: Glomerular expression of Drp1, phospho-Drp1 (Ser616) and Fis1 was mainly increased in children with NS with membranous nephropathy. No relationship was found between glomerular expression of Drp1, phospho-Drp1 (Ser616) and Fis1 and podocyte mitochondrial density or urinary protein measurements. Conclusion: Glomerular overproduction of Drp1, phospho-Drp1 (Ser 616) and Fis1 occurred mainly in children with membranous nephropathy. The pathological significance deserves further investigation.