tailieunhanh - Báo cáo khoa học: Sodium pump a1 and a3 subunit isoforms mediate distinct responses to ouabain and are both essential for survival of human neuroblastoma

Using SK-N-AS human neuroblastoma cells, which co-express thea1 and a3 isoforms of the sodium pumpasubunit, we selectively silenced either the a1ora3 subunit by means of transfection with small interfering RNA, and investigated cell survival and the cellular response to ouabain. | ỊFEBS Journal Sodium pump a1 and a3 subunit isoforms mediate distinct responses to ouabain and are both essential for survival of human neuroblastoma Larisa Karpova1 2 Alexander Eva1 Ulrike Kirch1 Alexander Boldyrev2 Georgios Scheiner-Bobis1 1 Institut fur Biochemie und Endokrinologie Fachbereich Veterinarmedizin Justus-Liebig-Universitat Giessen Germany 2 Department of Biochemistry Lomonosov Moscow State University Moscow Russia Keywords cardiotonic steroids Erk1 2 Na K -ATPase signaling SK-N-AS cells Correspondence G. Scheiner-Bobis Institut fur Biochemie und Endokrinologie Fachbereich Veterinarmedizin Justus-Liebig-Universitat Giessen Frankfurter Strasse 100 D-35392 Giessen Germany Fax 49 641 9938179 Tel 49 641 9938180 E-mail . Received 9 December 2009 revised 11 January 2010 accepted 1 February 2010 Using SK-N-AS human neuroblastoma cells which co-express the al and a3 isoforms of the sodium pump a subunit we selectively silenced either the a1 or a3 subunit by means of transfection with small interfering RNA and investigated cell survival and the cellular response to ouabain. We found that both of the a subunits are essential for cell survival indicating that substitution of one subunit for the other is not sufficient. In the presence of both a subunits ouabain causes sustained activation of extracellular signal-regulated kinases 1 and 2 Erk1 2 . This activation is not affected when the al subunit is silenced. However when a3 expression is silenced ouabain-induced activation of Erk1 2 does not occur even at a high concentration of ouabain 1 pM . Thus ouabain-induced Erk1 2 activation is mediated in SK-N-AS cells by a3 only and a1 does not participate in this event. This is a clear demonstration of selective involvement of a specific sodium pump a subunit isoform in ouabain-induced signaling. doi Introduction The sodium pump Na K -ATPase EC maintains the Na gradient across .