Neurofilament heavy polypeptide protects against reduction in synaptopodin expression and prevents podocyte detachment

Podocytes are highly specialized cells that line the glomerulus of the kidney and play a role in filtration. Podocyte injury plays a critical role in the development of many kidney diseases, but the underlying mechanisms remain unclear. In this study, we identified that neurofilament heavy polypeptide (NEFH), an intermediate filament component, protects podocyte from injury. We observed that NEFH was upregulated after ADRIAMYCIN(ADR)-induced podocyte injury in both mice and cultured murine podocytes. Immunofluorescence and co-immunoprecipitation analyses revealed that NEFH was colocalized with synaptopodin, a podocyte-specific marker. High NEFH expression in podocytes prevented the Adriamycin-induced reduction in synaptopodin expression. The siRNA-mediated knockdown of NEFH in podocytes reduced the number of vinculin-containing focal contacts, thereby reducing adhesion to the extracellular matrix and increasing podocyte detachment. In addition, NEFH expression was significantly increased in renal biopsy specimens from patients with focal segmental glomerulosclerosis and membranous nephropathy, but in those with minimal change disease. These findings indicate that NEFH is expressed in podocytes during the disease course and that it prevents the reduction in synaptopodin expression and detachment of podocytes.