Ankyrin-R regulates fast-spiking interneuron excitability through perineuronal nets and Kv3.1b K+ channels.

Sharon R Stevens,Matthew N Rasband,Anithachristy S Arumanayagam,Yuki Ogawa,Colleen M Longley,Supna Nair,Juan A Oses-Prieto,Lindsay H Teliska,Mingshan Xue,Alma L Burlingame,Matthew D Cykowski

doi:10.7554/elife.66491

Abstract

Neuronal ankyrins cluster and link membrane proteins to the actin and spectrin-based cytoskeleton. Among the three vertebrate ankyrins, little is known about neuronal Ankyrin-R (AnkR). We report AnkR is highly enriched in Pv+ fast-spiking interneurons in mouse and human. We identify AnkR-associated protein complexes including cytoskeletal proteins, cell adhesion molecules (CAMs), and perineuronal nets (PNNs). We show that loss of AnkR from forebrain interneurons reduces and disrupts PNNs, decreases anxiety-like behaviors, and changes the intrinsic excitability and firing properties of Pv+ fast-spiking interneurons. These changes are accompanied by a dramatic reduction in Kv3.1b K+ channels. We identify a novel AnkR-binding motif in Kv3.1b, and show that AnkR is both necessary and sufficient for Kv3.1b membrane localization in interneurons and at nodes of Ranvier. Thus, AnkR regulates Pv+ fast-spiking interneuron function by organizing ion channels, CAMs, and PNNs, and linking these to the underlying β1 spectrin-based cytoskeleton.

Highlights

Ion channels and cell adhesion molecules (CAMs) are frequently recruited to, stabilized, and maintained at specific neuronal membrane domains by scaffolding proteins
We found that Ankyrin-R 39 (AnkR) is highly enriched in the perisomatic region of a subset of neurons sparsely distributed throughout the cortex and hippocampus (Figure 1A)
141 AnkG in Pv+ neurons in cortex remained highly restricted to the axon initial segments (AIS) and nodes in all genotypes analyzed (Figure 1 - Supplement 1C and data not shown). These results show that 143 AnkR is abundantly expressed in Pv+ interneurons of the forebrain, that its localization is distinct from that of AnkB and AnkG, and that we have generated a floxed Ank[1] allele that allows for cell-type specific deletion in the nervous system

Summary

Introduction

Ion channels and cell adhesion molecules (CAMs) are frequently recruited to, stabilized, and maintained at specific neuronal membrane domains by scaffolding proteins. The ankyrin scaffolding proteins, consisting of Ankyrin-R, -B, and -G (AnkR, AnkB, and AnkG, respectively), are the primary link between the submembranous spectrin-based cytoskeleton and the cytoplasmic domains of many transmembrane proteins (Michaely and Bennett, 1995; Sedgwick and Smerdon, 1999). Ankyrins share a common structural organization including an N-terminal membrane binding domain consisting of 24 ankyrin repeats, a spectrin binding domain known as the ZZU domain, a death domain, and a more divergent and unstructured C-terminal domain that modulates interactions with other cytoskeletal proteins. Alternative splice variants of AnkB and AnkG arise from giant exon insertion between the spectrin binding domain and the death domain (Bennett and Lorenzo, 2013; Stevens and Rasband, 2021).

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Conclusion