MAP2

MAP2, or microtubule-associated protein 2, is a neuron-specific cytoskeletal protein belonging to the microtubule-associated protein family. It binds to and stabilizes microtubules, contributing to the organization and dynamics of dendritic arbors. MAP2 is predominantly expressed in the soma and dendrites of neurons, with relatively low levels in axons, and it plays a role in dendrite formation, growth, and plasticity.

Gene and isoforms: In mammals, the MAP2 gene generates multiple isoforms through alternative splicing, commonly labeled MAP2A, MAP2B, MAP2C, and MAP2D. The long isoforms (MAP2A and MAP2B) are enriched in mature neurons and dendrites, while the shorter isoforms (MAP2C and MAP2D) are more prominent during development and in certain neuronal populations. The proteins differ in domain composition and in their effects on microtubule stabilization and interactions with other cytoskeletal components.

Function and regulation: MAP2 stabilizes and bundles microtubules and can influence dendritic branching and spine morphology. Its association with microtubules is modulated by phosphorylation; kinases such as MAP kinase, GSK3, and CDK5 can reduce microtubule binding when MAP2 is phosphorylated, increasing cytoskeletal dynamics.

Clinical and research relevance: MAP2 serves as a key histological marker of dendrites in neuroscience research; antibodies against MAP2 label neuronal dendritic trees in tissue sections and cultured neurons. Altered MAP2 immunoreactivity or localization has been observed in several neurodegenerative conditions and brain injuries, reflecting dendritic loss or remodeling.