HMWMAP2: new perspectives on a pathway to dendritic identity.

Neuronal polarity is established by the differentiation of two types of cytoplasmic processes: dendrites and the axon. These processes can be distinguished by their composition in microtubule-associated proteins, the high molecular weight MAP2 proteins (HMWMAP2) being found in the dendrites and tau proteins in the axon. It is believed that the main contribution of HMWMAP2 to the acquisition and maintenance of dendrites is to promote microtubule assembly and stability. However, recent studies force us to enlarge our view on how HMWMAP2 might contribute to defining the role of the dendritic microtubules. The purpose of this article is to convey our view that HMWMAP2 are important players in defining the contribution of microtubules to dendritic identity by anchoring membranous organelles and signaling proteins to the dendritic microtubules and by being a receptor for neurosteroids. (c) 2008 Wiley-Liss, Inc.