The mechanosensitive K2P-channel TREK-1 is regulated by various physical and chemical stimuli, as well as interaction partners. The aim of this study was to characterize the interaction between TREK-1 and the enzyme HO-2, which catalyzes the breakdown of heme into biliverdin, Fe2+ and CO, and to clarify the functional consequences. Furthermore, the influence of CO on the TREK-1 channel was examined. The interaction between TREK-1 and HO-2 was confirmed by coimmunoprecipitation in HeLa cell

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... es. In addition, yeast-two-hybrid experiments with HO-2 deletion mutants showed that the distal carboxyterminus of HO-2 is crucial for the interaction with the TREK-1 channel. The functional consequences of this interaction were examined by using two-electrodevoltage- clamp (TEVC) measurements in Xenopus oocytes. Coexpression of human HO-2 and TREK-1 led to a significant increase of TREK-1 current amplitude, whereas coexpression of the catalytically inactive enzyme HO-2H45N, which still interacts with TREK-1, evoked no significant change in the TREK-1 current amplitude. The catalytic activity of HO-2 in Xenopus oocytes was modulated by application of HO-2 activators and inhibitors. Xenopus oocytes constitutively express HO-2. Application of Hemin, a HO-2 activator, led to a significant increase in TREK-1 currents. Additional coexpression of human HO-2 led to a significantly higher activation of TREK-1 currents. Application of zinc protoporphyrin, an HO-2 inhibitor, led to significant reduction of TREK-1 currents, which was higher after additional coexpression of human HO-2. Application of carbon monoxide (CO) via CO-releasing molecule CORM-2 produced a significant increase of TREK-1 currents in Xenopus oocytes and in HEK293 cells. Further studies with the PhotoCORM-S1 and CO gas also increased TREK-1 currents significantly. Furthermor [...]