Ankyrin G and voltage gated sodium channels colocalize in human neuroma – key proteins of membrane remodeling after axonal injury

2002 ◽  
Vol 323 (2) ◽  
pp. 151-155 ◽  
Author(s):  
Thomas Kretschmer ◽  
John D. England ◽  
Leo T. Happel ◽  
Z.P. Liu ◽  
Carol L. Thouron ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Axonal Injury ◽  
Membrane Remodeling ◽  
Voltage Gated ◽  
Ankyrin G ◽  
Voltage Gated Sodium Channels

scholarly journals Ankyrin-G coordinates assembly of the spectrin-based membrane skeleton, voltage-gated sodium channels, and L1 CAMs at Purkinje neuron initial segments

2001 ◽  
Vol 155 (5) ◽  
pp. 739-746 ◽  
Author(s):  
Scott M. Jenkins ◽  
Vann Bennett
Keyword(s):  
Adhesion Molecules ◽  
Sodium Channels ◽  
Action Potentials ◽  
Membrane Skeleton ◽  
Purkinje Neuron ◽  
Voltage Gated ◽  
Ankyrin G ◽  
Voltage Gated Sodium Channels ◽  
Cerebellar Purkinje Neurons ◽  
Axon Initial Segments

The axon initial segment is an excitable membrane highly enriched in voltage-gated sodium channels that integrates neuronal inputs and initiates action potentials. This study identifies Nav1.6 as the voltage-gated sodium channel isoform at mature Purkinje neuron initial segments and reports an essential role for ankyrin-G in coordinating the physiological assembly of Nav1.6, βIV spectrin, and the L1 cell adhesion molecules (L1 CAMs) neurofascin and NrCAM at initial segments of cerebellar Purkinje neurons. Ankyrin-G and βIV spectrin appear at axon initial segments by postnatal day 2, whereas L1 CAMs and Nav1.6 are not fully assembled at continuous high density along axon initial segments until postnatal day 9. L1 CAMs and Nav1.6 therefore do not initiate protein assembly at initial segments. βIV spectrin, Nav1.6, and L1 CAMs are not clustered in adult Purkinje neuron initial segments of mice lacking cerebellar ankyrin-G. These results support the conclusion that ankyrin-G coordinates the physiological assembly of a protein complex containing transmembrane adhesion molecules, voltage-gated sodium channels, and the spectrin membrane skeleton at axon initial segments.

scholarly journals βIV-spectrin regulates sodium channel clustering through ankyrin-G at axon initial segments and nodes of Ranvier

2002 ◽  
Vol 156 (2) ◽  
pp. 337-348 ◽  
Author(s):  
Masayuki Komada ◽  
Philippe Soriano
Keyword(s):  
Sodium Channels ◽  
Embryonic Stem ◽  
Nodes Of Ranvier ◽  
Gene Trapping ◽  
Voltage Gated ◽  
Ankyrin G ◽  
Membrane Cytoskeleton ◽  
Voltage Gated Sodium Channels ◽  
Axon Initial Segments ◽  
Sodium Channel Clustering

β-Spectrin and ankyrin are major components of the membrane cytoskeleton. We have generated mice carrying a null mutation in the βIV-spectrin gene using gene trapping in embryonic stem cells. Mice homozygous for the mutation exhibit tremors and contraction of hindlimbs. βIV-spectrin expression is mostly restricted to neurons, where it colocalizes with and binds to ankyrin-G at axon initial segments (AISs) and nodes of Ranvier (NR). In βIV-spectrin–null neurons, neither ankyrin-G nor voltage-gated sodium channels (VGSC) are correctly clustered at these sites, suggesting that impaired action potential caused by mislocalization of VGSC leads to the phenotype. Conversely, in ankyrin-G–null neurons, βIV-spectrin is not localized to these sites. These results indicate that βIV-spectrin and ankyrin-G mutually stabilize the membrane protein cluster and the linked membrane cytoskeleton at AIS and NR.

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