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Distinct modifications in Kv2.1 channel via chemokine receptor CXCR4 regulate neuronal survival-death dynamics. J Neurosci 2012 Dec 05;32(49):17725-39

Date

12/12/2012

Pubmed ID

23223293

Pubmed Central ID

PMC3544972

DOI

10.1523/JNEUROSCI.3029-12.2012

Scopus ID

2-s2.0-84870542038 (requires institutional sign-in at Scopus site)   30 Citations

Abstract

The chemokine stromal cell-derived factor-1α (SDF-1α) has multiple effects on neuronal activity, survival, and death under conditions that generate a proinflammatory microenvironment within the brain, via signaling through C-X-C-type chemokine receptor 4 (CXCR4), although the underlying cellular/molecular mechanisms are unclear. Using rat hippocampal neurons, we investigated distinct modifications in the voltage-gated K⁺ (Kv) channel Kv2.1 in response to short- and long-term SDF-1α/CXCR4-mediated signaling as an underlying mechanism for CXCR4-dependent regulation of neuronal survival and death. Acute exposure of neurons to SDF-1α led to dynamic dephosphorylation and altered localization of Kv2.1 channel, resulting in enhanced voltage-dependent activation of Kv2.1-based delayed-rectifier Kv currents (I(DR)). These changes were dependent on CXCR4- and/or NMDA receptor-mediated activation of calcineurin and provide neuroprotection. However, prolonged SDF-1α treatment leads to CXCR4-mediated activation of p38 mitogen-activated protein kinase, resulting in phosphorylation of Kv2.1 at S800 and enhanced surface trafficking of the channel protein, resulting in increased I(DR)/Kv2.1 current density. This, in combination with sustained dephosphorylation-induced enhancement of the voltage-dependent activation of I(DR)/Kv2.1, predisposed neurons to excessive K⁺ efflux, a vital step for the neuronal apoptotic program. Such apoptotic death was dependent on CXCR4 and Kv2.1 function and was absent in cells expressing the Kv2.1-S800A mutant channel. Furthermore, similar modifications in Kv2.1 and CXCR4/Kv2.1-dependent apoptosis were observed following treatment of neurons with the human immunodeficiency virus-1 (HIV-1) glycoprotein gp120. Therefore, distinct modifications in Kv2.1 in response to short- and long-term CXCR4-mediated signaling could provide a basis for neuroprotection or apoptosis in neuropathologies, such as neuroinflammation, stroke, brain tumors, and HIV-associated neurodegeneration.

Author List

Shepherd AJ, Loo L, Gupte RP, Mickle AD, Mohapatra DP

Author

Aaron D. Mickle PhD Associate Professor in the Physiology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
Apoptosis
Calcineurin
Calcineurin Inhibitors
Cell Death
Cell Survival
Chemokine CXCL12
Drug Interactions
Female
HEK293 Cells
HIV Envelope Protein gp120
Hippocampus
Humans
Male
Membrane Potentials
Mutant Proteins
Neurons
Phosphorylation
Primary Cell Culture
Rats
Rats, Sprague-Dawley
Receptors, CXCR4
Shab Potassium Channels
Signal Transduction
Tacrolimus
p38 Mitogen-Activated Protein Kinases