Paranodal junctions that flank nodes of Ranvier contain a cytoskeleton specialized to prevent membrane protein diffusion in and out of the nodes. This week Ogawa et al. used three known paranodal cell adhesion molecules to fish out additional paranodal molecules. As starting material, the authors isolated optic nerve membranes enriched in glial protein NF155 and the axonal proteins Caspr and contactin. Of 51 molecules identified by liquid chromatographytandem mass spectrometry, II spectrin, II spectrin, and ankyrinB cofractionated with Caspr as part of a paranodal complex. These proteins also associated with protein 4.1B. Immunostaining revealed these cytoskeletal proteins at paranodes in the central and peripheral nervous system. An enzymatic treatment that caused myelin retraction from the axon left II spectrin and ankyrinB staining intact, identifying them as axonal proteins. AnkyrinB localization required Caspr, but not the juxtaparanodal protein Caspr2, indicating that paranodal axonglia interactions are required for formation of the paranodal cytoskeleton.
2. Lining Up the Hair Cells
Mireille Montcouquiol, Nathalie Sans, David Huss, Jacob Kach, J. David Dickman, Andrew Forge, Rivka A. Rachel, Neal G. Copeland, Nancy A. Jenkins, Debora Bogani, Jennifer Murdoch, Mark E. Warchol, Robert J. Wenthold, and Matthew W. Kelley
How is it that cells in an epithelial sheet line up with the same orientation? In this week's Journal, Montcouquiol et al. examine some of the proteins involved in this planar cell polarity (PCP) problem in the mammalian system that perhaps best illustrates the process: cochlear hair cells. Mutations in mice have led to the identification of Vangl2, Scrb1, and Celsr1 as genes integral to PCP.
Contact: Sara Harris
Society for Neuroscience