Nitration of the low molecular weight neurofilament is equivalent in sporadic amyotrophic lateral sclerosis and control cervical spinal cord

To determine the extent to which enhanced nitration of the low molecular weight neurofilament subunit protein (NFL) is of pathogenic significance in sporadic ALS, we isolated the neurofilament (NF) from the cervical spinal cord of 15 cases of sporadic ALS and 11 age-matched control cases. Of the three NF subunits, only NFL demonstrated consistent nitrotyrosine immunoreactivity on immunoblots against mouse monoclonal anti-nitrotyrosine antibodies. Regardless of whether the NFL was isolated from the Triton X-100 soluble or insoluble cytoskeletal fractions, the extent of NFL nitration did not differ between ALS and control tissue. Similarly, no differences were observed on either two dimensional isoelectric focusing or NFL peptide maps. These findings suggest that NFL is particularly susceptible to peroxynitrite-mediated nitration in vivo but reveal no significant qualitative or quantitative modifications in the nitration of NFL isolated from sporadic ALS cervical spinal cord tissue as compared to non-ALS controls. (C) 1998 Academic Press.