Advanced glycation endproduct-modified superoxide dismutase-1 (SOD1)-positive inclusions are common to familial amyotrophic lateral sclerosis patients with SOD1 gene mutations and transgenic mice expressing human SOD1 with aG85R mutation

To clarify the biological significance of the neuronal Lewy body-like hyali ne inclusions and astrocytic hyaline inclusions characteristically found in patients with familial amyotrophic lateral sclerosis with superoxide dismu tase-1 (SOD1) gene mutations and in transgenic mice expressing human SOD1 w ith G85R mutation, the detailed protein composition in both types of inclus ions was immunohistochemically analyzed using 45 different antibodies. Both types of inclusions had very strong immunoreactivity for SOD1. The SOD1-po sitive inclusions in both cell types were also immunoreactive for the insol uble advanced glycation endproducts (AGEs) such as N-epsilon-(carboxymethyl )lysine (CML), pyrraline and pentosidine: both inclusions in both condition s were ultrastructurally composed of the granule-coated fibrils that had im munoreactivities to CML and pyrraline. Both types of inclusions were negati ve for stress-response proteins (SRPs), 4-hydroxy-2-nonenal (HNE), acrolein , nitric oxide synthases (NOSs) and nitrotyrosine as representative markers of oxidative stress. The neurons and astrocytes of the normal individuals and non-transgenic mice showed no significant immunoreactivity for SOD1, AG Es, SRPs, HNE, acrolein, NOSs or nitrotyrosine. Our results suggest that a portion of the SOD1 composing both type of inclusions, probably toxic mutan t SOD1, is modified by the AGEs, and that the formation of the AGE-modified SOD1 is one of the mechanisms responsible for the aggregation involving no significant oxidative mechanisms.