A Specific and Essential Role for Na,K-ATPase α3 in Neurons Co-expressing α1 and α3

Azarias, Guillaume; Kruusmägi, Markus; Connor, Siobhán; Akkuratov, Evgeny E.; Liu, Xiaoli; Lyons, David; Brismar, Hjalmar; Broberger, Christian; Aperia, Anita

doi:10.1074/jbc.m112.425785

Cited by 112 publications

(109 citation statements)

References 46 publications

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“…According to a recent study from our group, this modification will have consequences for the intracellular concentration of Na ϩ , which we have shown correlates with the apparent Na ϩ affinity (24). Our findings are in agreement with a previous study showing that the Na ϩ clearance rate decreases upon modulation of the Na ϩ ,K ϩ -ATPase ␣3 isoform by PKA (35). In the vicinity of Ser-938 in L8-9 are five charged residues, Asp-997, Glu-998, Arg-1000, Lys-1001, and Arg-1005, of M10 (Fig.…”

Section: Discussionsupporting

confidence: 82%

Importance of a Potential Protein Kinase A Phosphorylation Site of Na+,K+-ATPase and Its Interaction Network for Na+ Binding

Einholm

Nielsen

Holm

et al. 2016

Journal of Biological Chemistry

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The molecular mechanism underlying PKA-mediated regulation of Na ؉ ,K ؉ -ATPase was explored in mutagenesis studies of the potential PKA site at Ser-938 and surrounding charged residues. The phosphomimetic mutations S938D/E interfered with Na ؉ binding from the intracellular side of the membrane, whereas Na ؉ binding from the extracellular side was unaffected. Electrostatic interaction of Glu-998 is of minor importance for the reduction of Na ؉ affinity by phosphomimetic S938E as revealed by combining S938E with E998A.ATPase is a plasma membrane-associated ion pump protein that actively extrudes three Na ϩ ions from the cell while importing two K ϩ ions for each ATP being hydrolyzed (1-4). It is found in all animal cells where its main function is to establish and maintain transmembrane Na ϩ and K ϩ gradients that are fundamental to a variety of physiological processes ranging from electrical excitability of neurons in the brain to Na ϩ reabsorption in the kidney. The Na ϩ ,K ϩ -ATPase belongs to the superfamily of P-type ATPases and is a heterooligomeric protein consisting of a catalytic ␣-subunit, a ␤-subunit required for translocation of the protein complex to the plasma membrane, and a small regulatory protein belonging to the FXYD family (for reviews, see Refs. 4 and 5). The ␣-subunit is made up of a membrane part containing transmembrane helices 1-10 (M1-M10) 2 and a cytoplasmic "head" formed from three subdomains: actuator (A), nucleotide binding (N), and phosphorylation (P) domains (Fig. 1B). During the Na ϩ ,K ϩ -pump cycle (reaction scheme in Fig. 1A), ATP binds to the Nand P-domains, and the ␥-phosphate is transferred to a conserved aspartic acid residue of the P-domain. This phosphorylation is triggered by Na ϩ binding from the cytoplasmic side of the membrane, whereas dephosphorylation with release of inorganic phosphate is triggered by K ϩ binding from the extracellular side. The Na ϩ and K ϩ binding residues are found in the transmembrane helices M4, M5, M6, and M8 (6 -8). Na ϩ ,K ϩ -ATPase alternates between so-called E 1 and E 2 states (1, 2) (see reaction scheme in Fig. 1A). E 1 states bind Na ϩ at three sites denoted I, II, and III, whereas E 2 states prefer K ϩ , binding at two sites, I and II, that overlap considerably with Na ϩ sites I and II. The Na ϩ selectivity of site III is thought to arise in part from interactions of the two C-terminal tyrosines, stabilizing the position of the M5 helix, such that Na ϩ , but not the larger K ϩ ion, can fit into site III, which is the first of the three Na ϩ sites to be occupied when Na ϩ binds from the intracellular side (6,8,9). In addition to the autophosphorylation of the P-domain conserved aspartate, which is central to the reaction cycle of Na ϩ ,K ϩ -ATPase, the Na ϩ ,K ϩ -ATPase activity depends on regulatory phosphorylation by protein kinases (for a review, see Ref. 10). In cardiac myocytes, "kinase-mediated" phosphorylation of the FXYD1 protein stimulates Na ϩ ,K ϩ -ATPase (11). Furthermore, phosphorylation of the Na ϩ ,K ϩ -ATPase ␣-subunit...

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Section: Discussionsupporting

confidence: 82%

Importance of a Potential Protein Kinase A Phosphorylation Site of Na+,K+-ATPase and Its Interaction Network for Na+ Binding

Einholm

Nielsen

Holm

et al. 2016

Journal of Biological Chemistry

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“…To examine the membrane localization of the sodium pump isoforms, we applied SIM with lateral and axial resolution of approximately 100 nm and 275 nm, respectively, verified with fluorescent nanobead calibration. With improved axial sectioning, we demonstrate the expected high level of membrane localization of both ATP1a1 and ATP1a3 (Figure 2a,b) (Azarias et al 2013). Stack projections reveal an increased abundance in spine heads (Figure 2c) in contrast to a lower abundance in the thin spine neck.…”

Section: Resultsmentioning

confidence: 85%

“…Additionally, neuronal labeling by transfection results in exogenous expression in some cells, which allows for single cell examination and eliminates contamination from presynaptic branches or neighboring cells. This is a concern when examining a protein like the Na,K-ATPase which exists in both presynaptic and postsynaptic membranes (Pietrini et al 1992, Azarias et al 2013. However, fusion proteins should always be used with the caveat that they provide exogenous protein and possible overexpression.…”

Section: Resultsmentioning

confidence: 99%

Nanoscale elucidation of Na,K-ATPase isoforms in dendritic spines

et al. 2013

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Background: The dimensions of neuronal synapses suggest that optical super-resolution imaging methods are necessary for thorough investigation of protein distributions and interactions. Nanoscopic evaluation of neuronal samples has presented practical hurdles, but advancing methods are making synaptic protein topology and quantification measurements feasible. This work explores the application of Photoactivated Localization Microscopy (PALM) pointillistic super-resolution imaging for investigation of the membrane bound sodium pump, the Na,K-ATPase, in matured neurons.

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“…We have previously shown that ASPD colocalize with presynaptic Bassoon (19). Among different NAKα subunits, only NAKα3 is present in the presynaptic side of neurons (27,(46)(47)(48). Electrophysiological studies have also shown the importance of NAKα3 in the presynaptic function (49,50).…”

Section: Discussionmentioning

confidence: 94%

Na, K-ATPase α3 is a death target of Alzheimer patient amyloid-β assembly

Ohnishi

Yanazawa

Sasahara

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

119

155

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Neurodegeneration correlates with Alzheimer's disease (AD) symptoms, but the molecular identities of pathogenic amyloid β-protein (Aβ) oligomers and their targets, leading to neurodegeneration, remain unclear. Amylospheroids (ASPD) are AD patient-derived 10-to 15-nm spherical Aβ oligomers that cause selective degeneration of mature neurons. Here, we show that the ASPD target is neuronspecific Na + /K + -ATPase α3 subunit (NAKα3). ASPD-binding to NAKα3 impaired NAKα3-specific activity, activated N-type voltage-gated calcium channels, and caused mitochondrial calcium dyshomeostasis, tau abnormalities, and neurodegeneration. NMR and molecular modeling studies suggested that spherical ASPD contain N-terminal-Aβ-derived "thorns" responsible for target binding, which are distinct from low molecular-weight oligomers and dodecamers. The fourth extracellular loop (Ex4) region of NAKα3 encompassing Asn 879 and Trp 880 is essential for ASPD-NAKα3 interaction, because tetrapeptides mimicking this Ex4 region bound to the ASPD surface and blocked ASPD neurotoxicity. Our findings open up new possibilities for knowledge-based design of peptidomimetics that inhibit neurodegeneration in AD by blocking aberrant ASPD-NAKα3 interaction.NMR | computational modeling | abnormal protein-protein interaction in synapse | hyperexcitotoxicity | protein-protein interaction inhibitors

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A Specific and Essential Role for Na,K-ATPase α3 in Neurons Co-expressing α1 and α3

Abstract: Background: Neurons express two Na,K-ATPase isoforms, the ubiquitous ␣1 and neuron-specific ␣3. Results: ␣3 is important for control of membrane potential and is fully responsible for restoration of large [Na ϩ ] i increases.

Cited by 112 publications

References 46 publications

Importance of a Potential Protein Kinase A Phosphorylation Site of Na+,K+-ATPase and Its Interaction Network for Na+ Binding

Importance of a Potential Protein Kinase A Phosphorylation Site of Na+,K+-ATPase and Its Interaction Network for Na+ Binding

Nanoscale elucidation of Na,K-ATPase isoforms in dendritic spines

Na, K-ATPase α3 is a death target of Alzheimer patient amyloid-β assembly

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