Inter- and intracellular signaling in amyotrophic lateral sclerosis: role of p38 mitogen-activated protein kinase.

The pathogenetic processes underlying the selective motor neuron degeneration in amyotrophic lateral sclerosis (ALS) are complex and still not completely understood even in the cases of inherited disease caused by mutations in the Cu/Zn superoxide dismutase-dependent (SOD1) gene. Recent evidence supports the view that ALS is not a cell-autonomous disease and that glial-neuron cross-talk, throughout cytokines and other toxic factors like the nitric oxide and superoxide, is a crucial determinant for the induction of motor neuron death. This cell-cell interaction may determine the progression of the disease through processes that are likely independent of the initial trigger and that may converge on the activation of intracellular death pathways in the motor neurons. In this review we provide support to the hypothesis that aberrant expression and activity of p38 mitogen protein-activated kinases cascade (p38MAPK) in motor neurons and glial cells may play a role in the development and progression of ALS. Increased activation of p38MAPK may phosphorylate neuron-specific substrates altering their physiological properties and it may turn on responsive genes leading to neurotoxicity.