Neural cell adhesion molecule (NCAM) association with PKC beta sub(2) via beta I spectrin is implicated in NCAM-mediated neurite outgrowth

• Published in: The Journal of cell biology 2003-05, Vol.161 (3), p.625-639
• Main Authors: Leshchyns'ka, I, Sytnyk, V, Morrow, J S, Schachner, M
• Format: Article
• Language: English
• ISSN: 0021-9525
• DOI: 10.1083/jcb.200303020

In hippocampal neurons and transfected CHO cells, neural cell adhesion molecule (NCAM) 120, NCAM140, and NCAM180 form Triton X-100-insoluble complexes with beta I spectrin. Heteromeric spectrin ( alpha IssI) binds to the intracellular domain of NCAM180, and isolated spectrin subunits bind to both NCAM180 and NCAM140, as does the beta I spectrin fragment encompassing second and third spectrin repeats ( beta I sub(2-3)). In NCAM120-transfected cells, beta I spectrin is detectable predominantly in lipid rafts. Treatment of cells with methyl- beta -cyclodextrin disrupts the NCAM120-spectrin complex, implicating lipid rafts as a platform linking NCAM120 and spectrin. NCAM140/NCAM180- beta I spectrin complexes do not depend on raft integrity and are located both in rafts and raft-free membrane domains. PKC beta sub(2) forms detergent-insoluble complexes with NCAM140/NCAM180 and spectrin. Activation of NCAM enhances the formation of NCAM140/NCAM180-spectrin-PKC beta sub(2) complexes and results in their redistribution to lipid rafts. The complex is disrupted by the expression of dominant-negative beta I sub(2-3), which impairs binding of spectrin to NCAM, implicating spectrin as the bridge between PKC beta sub(2) and NCAM140 or NCAM180. Redistribution of PKC beta sub(2) to NCAM-spectrin complexes is also blocked by a specific fibroblast growth factor receptor inhibitor. Furthermore, transfection with beta I sub(2-3) inhibits NCAM-induced neurite outgrowth, showing that formation of the NCAM-spectrin-PKC beta sub(2) complex is necessary for NCAM-mediated neurite outgrowth.