Referenced in: none

Automatically associated channels: Kv1.1 , Kv1.2 , Kv1.6

Title: K+ channel distribution and clustering in developing and hypomyelinated axons of the optic nerve.

Authors: M N Rasband, J S Trimmer, E Peles, S R Levinson, P Shrager

Journal, date & volume: J. Neurocytol., 1999 Apr-May , 28, 319-31

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/10739574

Abstract
The localization of Shaker-type K(+) channels in specialized domains of myelinated central nervous system axons was studied during development of the optic nerve. In adult rats Kv1.1, Kv1.2, Kv1.6, and the cytoplasmic beta-subunit Kvbeta2 were colocalized in juxtaparanodal zones. During development, clustering of K(+) channels lagged behind that for nodal Na(+) channels by about 5 days. In contrast to the PNS, K(+) channels were initially expressed fully segregated from nodes and paranodes, the latter identified by immunofluorescence of Caspr, a component of axoglial junctions. Clusters of K(+) channels were first detected at postnatal day 14 (P14) at a limited number of sites. Expression increased until all juxtaparanodes had immunoreactivity by P40. Developmental studies in hypomyelinating Shiverer mice revealed dramatically disrupted axoglial junctions, aberrant Na(+) channel clusters, and little or no detectable clustering of K(+) channels at all ages. These results suggest that in the optic nerve, compact myelin and normal axoglial junctions are essential for proper K(+) channel clustering and localization.