Change in superoxide dismutase 1 protein localization towards mitochondria: an immunohistochemical study in transgenic G93A mice.

ABSTRACT

Localization of superoxide dismutase1 (SOD1) and mitochondrial glucose-regulated protein 75 (Grp75), were examined in the spinal cords of transgenic (Tg) mice expressing human mutant SOD1 protein (G93A) and wild-type (Wt) controls at 8, 20 and 32 weeks. SOD1 showed a progressive increase of dot-like deposits in the neuropil of anterior horn of Tg mice, and a late decrease of signal intensity in the white matter and motor neurons. Colocalization of Grp75 and SOD1 signals was demonstrated in Wt and presymptomatic Tg animals, while it was lost in Tg mice at a symptomatic age. The present results suggest that loss of SOD1 protein from mitochondria could contribute to motor neuron damage.