CLDN5 and amyotrophic lateral sclerosis: In mouse models of ALS-causing SOD1 mutants, deficiency of SOD1 reduced the levels of the tight junction proteins ZO-1, occludin and claudin-5 between endothelial cells and destroyed the blood-spinal barrier, which resulted in microbleedings and hypoperfusion of microcirculation (Zhong et al., 2008).