Fibronectin type III-like domains of neurofascin-186 protein mediate gliomedin binding and its clustering at the developing nodes of Ranvier.
The cell adhesion molecules (CAMs) of the immunoglobulin superfamily (Ig-CAMs) play a crucial role in the organization of the node of Ranvier in myelinated axons. In the peripheral nervous system, Gliomedin (Gldn) secreted by Schwann cell microvilli binds NgCAM-related CAM (NrCAM) and Neurofascin-186 (NF186) and direct the nodal clustering of voltage-gated sodium channels (Nav). NF186 is the single axonal Gldn partner to ensure Nav clustering at nodes, whereas NrCAM is only required in glial cells (Feinberg, K., Eshed-Eisenbach, Y., Frechter, S., Amor, V., Salomon, D., Sabanay, H., Dupree, J. L., Grumet, M., Brophy, P. J., Shrager, P., and Peles, E. (2010) Neuron 65, 490-502). The olfactomedin domain of Gldn is implicated in the interaction with nodal Ig-CAMs. However, the interacting modules of NrCAM or NF186 involved in Gldn association are unknown. Here, we report that fibronectin type III-like (FnIII) domains of both Ig-CAMs mediate their interaction with Gldn in pulldown and cell binding assays. Using surface plasmon resonance assays, we determined that NrCAM and NF186 display similar affinity constant for their association with Gldn (K(D) of 0.9 and 5.7 nm, respectively). We characterized the FnIII domains 1 and 2 of NF186 as interacting modules that ensure association with Gldn. We found that the soluble FnIII domains of NF186 (FnIII-Fc) bind on Schwann cells and inhibit Gldn and Nav clustering at heminodes, the precursors of mature nodes in myelinating cultures. Our study reveals the unexpected importance of FnIII domains of Ig-CAMs in the organization of nodes of Ranvier in peripheral axons. Thus, NF186 utilizes distinct modules to organize the multimeric nodal complex.
Aix-Marseille Université, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, 13344 Marseille, France; CNRS UMR 6231, 13344 Marseille, France.
Marilyne
M
Labasque
Aix-Marseille Université, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, 13344 Marseille, France; CNRS UMR 6231, 13344 Marseille, France.
Jérôme J
JJ
Devaux
Centre d'Analyse Protéomique de Marseille, 13344 Marseille, France.
Christian
C
Lévêque
Aix-Marseille Université, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, 13344 Marseille, France; CNRS UMR 6231, 13344 Marseille, France. Electronic address: catherine.sarrailh@univmed.fr.
Catherine
C
Faivre-Sarrailh
D001369:Axons / Q000378:metabolism*; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000737:chemistry*; D002460:Cell Line; D045744:Cell Line, Tumor; D005353:Fibronectins / Q000737:chemistry*; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins; D009186:Myelin Sheath / Q000737:chemistry; D009414:Nerve Growth Factors / Q000737:chemistry*; D009419:Nerve Tissue Proteins; D019006:Neural Cell Adhesion Molecules / Q000737:chemistry*; D009457:Neuroglia / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011901:Ranvier's Nodes / Q000378:metabolism*; D012583:Schwann Cells / Q000378:metabolism; D020349:Surface Plasmon Resonance
D015815:Cell Adhesion Molecules; D005353:Fibronectins; C473138:GLDN protein, human; D008565:Membrane Proteins; C054305:NFASC protein, human; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D019006:Neural Cell Adhesion Molecules