Targeting a Potassium Channel/Syntaxin Interaction Ameliorates Cell Death in Ischemic Stroke.

Abstract

The voltage-gated K+ channel Kv2.1 has been intimately linked with neuronal apoptosis. After ischemic, oxidative, or inflammatory insults, Kv2.1 mediates a pronounced, delayed enhancement of K+ efflux, generating an optimal intracellular environment for caspase and nuclease activity, key components of programmed cell death. This apoptosis-enabling mechanism is initiated via Zn2+-dependent dual phosphorylation of Kv2.1, increasing the interaction between the channel's intracellular C-terminus domain and the SNARE (soluble N-ethylmaleimide-sensitive factor activating protein receptor) protein syntaxin 1A. Subsequently, an upregulation of de novo channel insertion into the plasma membrane leads to the critical enhancement of K+ efflux in damaged neurons. Here, we investigated whether a strategy designed to interfere with the cell death-facilitating properties of Kv2.1, specifically its interaction with syntaxin 1A, could lead to neuroprotection following ischemic injury in vivo The minimal syntaxin 1A-binding sequence of Kv2.1 C terminus (C1aB) was first identified via a far-Western peptide screen and used to create a protherapeutic product by conjugating C1aB to a cell-penetrating domain. The resulting peptide (TAT-C1aB) suppressed enhanced whole-cell K+ currents produced by a mutated form of Kv2.1 mimicking apoptosis in a mammalian expression system, and protected cortical neurons from slow excitotoxic injury in vitro, without influencing NMDA-induced intracellular calcium responses. Importantly, intraperitoneal administration of TAT-C1aB in mice following transient middle cerebral artery occlusion significantly reduced ischemic stroke damage and improved neurological outcome. These results provide strong evidence that targeting the proapoptotic function of Kv2.1 is an effective and highly promising neuroprotective strategy.SIGNIFICANCE STATEMENT Kv2.1 is a critical regulator of apoptosis in central neurons. It has not been determined, however, whether the cell death-enabling function of this K+ channel can be selectively targeted to improve neuronal survival following injury in vivo The experiments presented here demonstrate that the cell death-specific role of Kv2.1 can be uniquely modulated to provide neuroprotection in an animal model of acute ischemic stroke. We thus reveal a novel therapeutic strategy for neurological disorders that are accompanied by Kv2.1-facilitated forms of cell death.

• Authors: Chung-Yang Yeh, Ashlyn M Bulas, Aubin Moutal, Jami L Saloman, Karen A Hartnett, Charles T Anderson, Thanos Tzounopoulos, Dandan Sun, Rajesh Khanna, Elias Aizenman
• Journal: The Journal of neuroscience : the official journal of the Society for Neuroscience (J Neurosci) Vol. 37 Issue 23 Pg. 5648-5658 (06 07 2017) ISSN: 1529-2401 [Electronic] United States
• PMID: 28483976 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2017 the authors 0270-6474/17/375648-11$15.00/0.

Chemical References

• Kv1.2 Potassium Channel
• Neuroprotective Agents
• Potassium Channel Blockers
• Qa-SNARE Proteins

Topics

• Animals
• Apoptosis (drug effects)
• Cells, Cultured
• Drug Delivery Systems (methods)
• Female
• Kv1.2 Potassium Channel (antagonists & inhibitors, metabolism)
• Male
• Neuroprotective Agents (administration & dosage)
• Potassium Channel Blockers (administration & dosage)
• Qa-SNARE Proteins (antagonists & inhibitors, metabolism)
• Rats
• Stroke (drug therapy, pathology, physiopathology)
• Treatment Outcome