| First Author | Stoica A | Year | 2017 |
| Journal | Glia | Volume | 65 |
| Issue | 11 | Pages | 1777-1793 |
| PubMed ID | 28787093 | Mgi Jnum | J:245951 |
| Mgi Id | MGI:5914314 | Doi | 10.1002/glia.23194 |
| Citation | Stoica A, et al. (2017) The alpha2beta2 isoform combination dominates the astrocytic Na+ /K+ -ATPase activity and is rendered nonfunctional by the alpha2.G301R familial hemiplegic migraine type 2-associated mutation. Glia 65(11):1777-1793 |
| abstractText | Synaptic activity results in transient elevations in extracellular K+ , clearance of which is critical for sustained function of the nervous system. The K+ clearance is, in part, accomplished by the neighboring astrocytes by mechanisms involving the Na+ /K+ -ATPase. The Na+ /K+ -ATPase consists of an alpha and a beta subunit, each with several isoforms present in the central nervous system, of which the alpha2beta2 and alpha2beta1 isoform combinations are kinetically geared for astrocytic K+ clearance. While transcript analysis data designate alpha2beta2 as predominantly astrocytic, the relative quantitative protein distribution and isoform pairing remain unknown. As cultured astrocytes altered their isoform expression in vitro, we isolated a pure astrocytic fraction from rat brain by a novel immunomagnetic separation approach in order to determine the expression levels of alpha and beta isoforms by immunoblotting. In order to compare the abundance of isoforms in astrocytic samples, semi-quantification was carried out with polyhistidine-tagged Na+ /K+ -ATPase subunit isoforms expressed in Xenopus laevis oocytes as standards to obtain an efficiency factor for each antibody. Proximity ligation assay illustrated that alpha2 paired efficiently with both beta1 and beta2 and the semi-quantification of the astrocytic fraction indicated that the astrocytic Na+ /K+ -ATPase is dominated by alpha2, paired with beta1 or beta2 (in a 1:9 ratio). We demonstrate that while the familial hemiplegic migraine-associated alpha2.G301R mutant was not functionally expressed at the plasma membrane in a heterologous expression system, alpha2+/G301R mice displayed normal protein levels of alpha2 and glutamate transporters and that the one functional allele suffices to manage the general K+ dynamics. |
