ALS associated mutant SOD1 impairs the motor neurons and astrocytes and wild type astrocyte secreted-factors reverse the impaired motor neurons.

Amyotrophic Lateral Sclerosis, in which motor neurons degenerate, leading to paralysis, not only the affected motor neurons, but the surrounding non-neuronal cells also contribute significantly to the disease. However, the disease mechanism is not known. In this study we have addressed the disease mechanism by expressing the ALS associated mutant SOD1(G37R) in the motor neurons (mMN) and astrocytes (mA) cell lines. A series of cell culture assays, immunostaining, RT-PCR and Western blot analysis were performed. We noticed impairments in both these cell types. The mMN motor neurons were insensitive to forskolin, a known activator of adenylate cyclase, which leads to motor neuron death. In addition, less number of mMN were positive for phosphorylated neurofilament-H (pNFH) unlike the normal motor neurons. Similarly, the mutant SOD1 expressing astrocytes (mA) had two impairments: The inability to activate the oxidative stress protection and the absence of secretory factor(s). Normal astrocytes and their secreted factors could restore the pNFH in the mMN but not the mA. In addition, we show that pNFH restoration is a specific function since the insensitivity of mMN to forskolin could be rescued by neither normal astrocytes nor their secreted factors. Thus we demonstrate some of the abnormalities caused by the ALS associated mutant SOD1(G37R) and a potential way, to reverse an abnormality through cell replacement.