Cosignaling of NCAM via lipid rafts and the FGF receptor is required for neuritogenesis

Abstract

The neural cell adhesion molecule (NCAM) has been reported to stimulate neuritogenesis either via nonreceptor tyrosine kinases or fibroblast growth factor (FGF) receptor. Here we show that lipid raft association of NCAM is crucial for activation of the nonreceptor tyrosine kinase pathway and induction of neurite outgrowth. Transfection of hippocampal neurons of NCAM-deficient mice revealed that of the three major NCAM isoforms only NCAM140 can act as a homophilic receptor that induces neurite outgrowth. Disruption of NCAM140 raft association either by mutation of NCAM140 palmitoylation sites or by lipid raft destruction attenuates activation of the tyrosine focal adhesion kinase and extracellular signal–regulated kinase 1/2, completely blocking neurite outgrowth. Likewise, NCAM-triggered neurite outgrowth is also completely blocked by a specific FGF receptor inhibitor, indicating that cosignaling via raft-associated kinases and FGF receptor is essential for neuritogenesis.

Functional Role of the Interaction between Polysialic Acid and Myristoylated Alanine-rich C Kinase Substrate at the Plasma Membrane

“…Phospho-MARCKS antibody (sc-12971) recognizing Ser(P)-159/163 was from Santa Cruz Biotechnology (Santa Cruz, CA), and the GFP antibody was from Rockland Immunochemicals (Gilbertsville, PA). Polyclonal NCAM antibody 1␤2 against the extracellular domain of NCAM has been described (23). Polyclonal antibody against tubulin was from Covance (Princeton, NJ).…”

Lipid Raft-dependent Endocytosis of Close Homolog of Adhesion Molecule L1 (CHL1) Promotes Neuritogenesis

“…1A). We have described that cysteine residues in the intracellular domain of the neural cell adhesion molecule (NCAM) are palmitoylated, and this palmitoylation leads to the targeting of NCAM to lipid rafts and contributes to signaling events following activation of NCAM at the cell surface (28). Hence, we investigated whether CHL1 would also be palmitoylated.…”

L1 and NCAM adhesion molecules as signaling coreceptors in neuronal migration and process outgrowth

“…NCAM signaling to ERK is more complex than L1-ERK signaling and involves interactions with different receptors. For example, NCAM signaling within lipid rafts is independent of the fibroblast growth factor (FGF) receptor, whereas a component of NCAM-ERK signaling in non-rafts is FGF receptordependent [26]. The NCAM-FGR receptor pathway further differs by signaling through phospholipase C γ and protein kinase C [27].…”

“…* of special interest: references 3,6,18,20,26,33,37 ** of exceptional interest as follows: ** 10. The authors used BAC transgenic reporter mice expressing green fluorescent protein in an interneuron subpopulation to show that a subcellular gradient of the Neurofascin 186 isoform along the dendritic-somal-axon initial segment axis of cerebellar Purkinje cells is formed by direct interaction with an ankyrin B isoform, and is responsible for axon targeting of basket interneurons to the axon initial segment.…”