Ouabain Modulates the Functional Interaction Between Na,K-ATPase and NMDA Receptor
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ORIGINAL ARTICLE
Ouabain Modulates the Functional Interaction Between Na,K-ATPase and NMDA Receptor Evgeny E. Akkuratov 1 & Linda Westin 2 & Erika Vazquez-Juarez 3 & Minttu de Marothy 2 & Aleksandra K. Melnikova 4 & Hans Blom 1 & Maria Lindskog 3 & Hjalmar Brismar 1 & Anita Aperia 2 Received: 27 January 2020 / Accepted: 8 June 2020 # The Author(s) 2020
Abstract The N-methyl-D-aspartate (NMDA) receptor plays an essential role in glutamatergic transmission and synaptic plasticity and researchers are seeking for different modulators of NMDA receptor function. One possible mechanism for its regulation could be through adjacent membrane proteins. NMDA receptors coprecipitate with Na,K-ATPase, indicating a potential interaction of these two proteins. Ouabain, a mammalian cardiotonic steroid that specifically binds to Na,K-ATPase and affects its conformation, can protect from some toxic effects of NMDA receptor activation. Here we have examined whether NMDA receptor activity and downstream effects can be modulated by physiological ouabain concentrations. The spatial colocalization between NMDA receptors and the Na,K-ATPase catalytic subunits on dendrites of cultured rat hippocampal neurons was analyzed with superresolution dSTORM microscopy. The functional interaction was analyzed with calcium imaging of single hippocampal neurons exposed to 10 μM NMDA in presence and absence of ouabain and by determination of the ouabain effect on NMDA receptor– dependent long-term potentiation. We show that NMDA receptors and the Na,K-ATPase catalytic subunits alpha1 and alpha3 exist in same protein complex and that ouabain in nanomolar concentration consistently reduces the calcium response to NMDA. Downregulation of the NMDA response is not associated with internalization of the receptor or with alterations in its state of Src phosphorylation. Ouabain in nanomolar concentration elicits a long-term potentiation response. Our findings suggest that ouabain binding to a fraction of Na,K-ATPase molecules that cluster with the NMDA receptors will, via a conformational effect on the NMDA receptors, cause moderate but consistent reduction of NMDA receptor response at synaptic activation.
Evgeny E. Akkuratov and Linda Westin contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12035-020-01984-5) contains supplementary material, which is available to authorized users. * Hjalmar Brismar [email protected]
Maria Lindskog [email protected]
Evgeny E. Akkuratov [email protected] Linda Westin [email protected] Erika Vazquez-Juarez [email protected]
Anita Aperia [email protected] 1
Science for Life Laboratory, Department of Applied Physics, Kungliga Tekniska Högskolan, Stockholm, Sweden
2
Science for Life Laboratory, Department of Women’s and Children’s health, Karolinska Institutet, Stockholm, Sweden
3
Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
4
Faculty of Bioengineering and Bioinformatics, Lomo
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