SUMOylation of NaV1.2 channels mediates the early response to acute hypoxia in central neurons

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Abstract

The mechanism for the earliest response of central neurons to hypoxia-an increase in voltage-gated sodium current (I_Na)-has been unknown. Here, we show that hypoxia activates the Small Ubiquitin-like Modifier (SUMO) pathway in rat cerebellar granule neurons (CGN) and that SUMOylation of Na_V1.2 channels increases I_Na. The time-course for SUMOylation of single NaV₁.2 channels at the cell surface and changes in I_Na coincide, and both are prevented by mutation of Na_V1.2-Lys38 or application of a deSUMOylating enzyme. Within 40 s, hypoxia-induced linkage of SUMO1 to the channels is complete, shifting the voltage-dependence of channel activation so that depolarizing steps evoke larger sodium currents. Given the recognized role of I_Na in hypoxic brain damage, the SUMO pathway and Na_V1.2 are identified as potential targets for neuroprotective interventions.

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Leigh D Plant

Department of Biochemistry, Brandeis University, Waltham, United States

For correspondence
ldplant@brandeis.edu

Competing interests
The authors declare that no competing interests exist.
Jeremy D Marks

Department of Pediatrics, University of Chicago, Chicago, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-2644-5257
Steven AN Goldstein

Department of Biochemistry, Brandeis University, Waltham, United States

For correspondence
goldstein@brandeis.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-5207-5061

Funding

National Institute of Neurological Disorders and Stroke (R01NS058505)

Steven AN Goldstein

National Institute of Neurological Disorders and Stroke (R01NS056313)

Jeremy D Marks

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: University of Chicago Institutional Animal Care and Use Committee (IACUC) approved the use of vertebrate animals (rats) in protocol #68001 to J. Marks.Brandeis University Institutional Animal Care and Use Committee (IACUC), operating under Animal Welfare Assurance #A3445-01, approved the use of vertebrate animals (rats) in protocol #0910-09 to Suzanne Paradis.The neurons are studied by various techniques, including electrophysiology, immunocytochemistry and microscopy. Invertebrate model systems are not useful here because the proteins we study are not present in their genome. Where possible we use tissue culture cells, however, much of the work focuses on how native ion channels are expressed and regulated. Rodents are the lowest phylogenetic order in which we can carry out the experiments we propose. Rats are also the standard organism for studies of cerebellar granule neuron physiology and are well established in the field as the organism of choice for the studies proposed. Thus, there is an extensive literature against which to compare and interpret the experimental results. Rats are frequently the source of neurons for cultures due to the large size of their brains and the relative robustness of their neurons in culture. The rat is a well-accepted model for studying ischemia in vitro, providing several advantages: a) the vulnerability of the rodent nervous system to hypoxia-ischemia is well-characterized, b) that rat shares identical mechanisms of ischemia-induced neuronal death with humans and c) procedures for minimizing discomfort, distress, pain, and injury as well as for euthanasia are extensively studied and ours follow AVMA guidelines.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.