SMN loss dysregulates microtubule-associated proteins in spinal muscular atrophy model.

Spinal muscular atrophy (SMA) is a rare neurodegenerative disease caused by the absence of survival motor neuron (SMN) protein. SMN loss results in impairments of the cytoskeleton, including microtubules and regulatory proteins. However, the contribution of microtubule-associated proteins (MAPs) to microtubule dysregulations in SMA is not fully understood. In this study, we investigated neuronal MAPs responsible for the microtubule stability and growth, including MAP1A, MAP2, MAP6, MAP7, EB1, and EB3 using an in vitro model of SMA. Decreased MAP2 and EB3 levels were found in SMN-deficient motor neuron-like cells, and EB3 protein level was also relevant to MAP1B. SMN loss leads to an increase in EB3 comet numbers at proximal neurites, indicating increased microtubule growth. Our findings suggest that SMN deficiency simultaneously causes dysregulations of several MAPs, contributing to the perturbations of microtubule dynamics in SMA.