A somatic afterhyperpolarization is driven by ion channel nodes expressed across a polygonal spectrin cytoskeleton

Abstract

A spectrin-actin cytoskeleton defines the structure of axons and expression of ion channels that support spike propagation, but it is not known how calcium and potassium channels are organized at the soma to control spike output patterns. The hippocampal pyramidal cell slow afterhyperpolarization (sAHP) is generated by a CaRyK protein complex of Cav1.3 calcium, RyR2, and IK potassium channels reflecting an ER-PM junction. Super resolution imaging and dimension reduction identified a highly organized distribution of CaRyK protein clusters aligned as rows with [~]155 nm periodicity that extended to branchpoints to form a non-rigid lattice-like structure across the soma. All CaRyK proteins proved to align and colocalize with the polygonal spectrin {beta}II cytoskeleton. The data indicate that CaRyK proteins at ER-PM junctions that contribute to the sAHP to control the pattern of spike output are distributed with high precision as functional ion channel nodes across the somatic spectrin cytoskeletal network. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=120 HEIGHT=200 SRC="FIGDIR/small/607230v4_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@1a60adorg.highwire.dtl.DTLVardef@1c11894org.highwire.dtl.DTLVardef@34b50aorg.highwire.dtl.DTLVardef@59bb39_HPS_FORMAT_FIGEXP M_FIG C_FIG