Developing nodes of Ranvier are defined by ankyrin-G clustering and are independent of paranodal axoglial adhesion
AUTOR(ES)
Jenkins, Scott M.
FONTE
The National Academy of Sciences
RESUMO
Nodes of Ranvier are excitable regions of axonal membranes highly enriched in voltage-gated sodium channels that propagate action potentials. The mechanism of protein clustering at nodes has been a source of controversy. In this study, developmental analysis of nodes of Ranvier in optic nerve axons reveals that early node intermediates are defined by ankyrin-G. Other node components, including beta IV spectrin, voltage-gated sodium channels, and the L1 cell adhesion molecule neurofascin, are subsequently recruited to sites of ankyrin-G clustering. The role of intact paranodes in protein clustering was examined in the dysmyelinating mouse mutant jimpy. Jimpy mice do not have intact paranodal axoglial contacts, which is indicated by a complete lack of neurexin/contactin-associated protein/paranodin clustering in paranodes. In the absence of intact paranodes, ankyrin-G was still able to cluster, although fewer ankyrin clusters were seen in jimpy optic nerves than in wild-type optic nerves. Recruitment of Nav1.2, Nav1.6, beta IV spectrin, and neurofascin to sites of ankyrin-G clustering is unimpaired in jimpy mice, indicating that node formation occurs independent of intact paranodal axoglial contacts.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=122360Documentos Relacionados
- Nav1.5 E1053K mutation causing Brugada syndrome blocks binding to ankyrin-G and expression of Nav1.5 on the surface of cardiomyocytes
- Sodium channel Nav1.6 is localized at nodes of Ranvier, dendrites, and synapses
- The local chemical environment of nodes of Ranvier: a study of cation binding.
- Heinz bodies induce clustering of band 3, glycophorin, and ankyrin in sickle cell erythrocytes.
- Nodes of Ranvier form in association with ezrin-radixin-moesin (ERM)-positive Schwann cell processes