Expression and function of Kv7.4 channels in rat cardiac mitochondria: possible targets for cardioprotection. Issue 1 (29th December 2015)

• Record Type: Journal Article
• Authors: Testai, Lara; Barrese, Vincenzo; Soldovieri, Maria Virginia; Ambrosino, Paolo; Martelli, Alma; Vinciguerra, Iolanda; Miceli, Francesco; Greenwood, Iain Andrew; Curtis, Michael John; Breschi, Maria Cristina; Sisalli, Maria Josè; Scorziello, Antonella; Canduela, Miren Josune; Grandes, Pedro; Calderone, Vincenzo; Taglialatela, Maurizio
• Is Part Of: Cardiovascular research. Volume 110:Issue 1(2016)
• Page Start: 40
• Page End: 50
• Publication Date: 2015-12-29
• Subjects: Kv7 potassium channels -- Mitochondria -- Retigabine -- Ischaemia–reperfusion cardiac damage -- Cardioprotection; Cardiovascular system -- Diseases -- Periodicals; Cardiovascular system -- Periodicals; 616.1
• DOI: 10.1093/cvr/cvv281
• Languages: English
• ISSNs: 0008-6363

Abstract

Abstract: Aims: Plasmalemmal Kv7.1 (KCNQ1) channels are critical players in cardiac excitability; however, little is known on the functional role of additional Kv7 family members (Kv7.2-5) in cardiac cells. In this work, the expression, function, cellular and subcellular localization, and potential cardioprotective role against anoxic-ischaemic cardiac injury of Kv7.4 channels have been investigated. Methods and results: Expression of Kv7.1 and Kv7.4 transcripts was found in rat heart tissue by quantitative polymerase chain reaction. Western blots detected Kv7.4 subunits in mitochondria from Kv7.4-transfected cells, H9c2 cardiomyoblasts, freshly isolated adult cardiomyocytes, and whole hearts. Immunofluorescence experiments revealed that Kv7.4 subunits co-localized with mitochondrial markers in cardiac cells, with ∼30–40% of cardiac mitochondria being labelled by Kv7.4 antibodies, a result also confirmed by immunogold electron microscopy experiments. In isolated cardiac (but not liver) mitochondria, retigabine (1–30 µM) and flupirtine (30 µM), two selective Kv7 activators, increased Tl + influx, depolarized the membrane potential, and inhibited calcium uptake; all these effects were antagonized by the Kv7 blocker XE991. In intact H9c2 cells, reducing Kv7.4 expression by RNA interference blunted retigabine-induced mitochondrial membrane depolarization; in these cells, retigabine decreased mitochondrial Ca 2+ levels and increased radical oxygen species production, both effects prevented by XE991. Finally, retigabine reduced cellular damage in H9c2 cells exposed to anoxia/re-oxygenation and largely prevented the functional and morphological changes triggered by global ischaemia/reperfusion (I/R) in Langendorff-perfused rat hearts. Conclusion: Kv7.4 channels are present and functional in cardiac mitochondria; their activation exerts a significant cardioprotective role, making them potential therapeutic targets against I/R-induced cardiac injury.