The mitochondrial K-ATP channel opener diazoxide upregulates STIM1 and Orai1 via ROS and the MAPK pathway in adult rat cardiomyocytes

Abstract

Background: Openers of mitochondrial adenosine triphosphate-dependent potassium (mKATP) channels like diazoxide increase reactive oxygen species (ROS) production in cardiac cells and reduce Ca2+ elevations produced by ischemia-reperfusion protecting the heart from damage. In this study we tested the hypothesis that opening mKATP channels regulates expression of the major components of store-operated Ca2+ entry (SOCE) STIM1 and Orai1. Methods: Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and western blot techniques were used to assess mRNA expression and protein abundance of STIM1 and Orai1. Confocal immunofluorescence imaging was used to visualize the distribution and localization of STIM1 and Orai1 and translocation of transcription factors NFkB and c-Fos into the nucleus.Results: Diazoxide increased expression of STIM1 and Orai1 at the mRNA and protein levels, respectively, in adult rat cardiomyocytes. Diazoxide also disrupted the striated distribution pattern of STIM1. These effects were prevented by the ROS scavenger N-acetyl cysteine (NAC), the mKATP channel antagonist 5-hydroxydecanoate (5-HD), or the protein synthesis inhibitor cycloheximide (CHX). Diazoxide also led to nuclear translocation of the transcription factors c-Fos and NFkB, which was also blocked by NAC or 5-HD. Finally, the MAPK pathway inhibitor UO126 attenuated diazoxide-induced upregulation of STIM1 and Orai1 expression Conclusions: Our results suggest that opening mitochondrial potassium ATP channels with diazoxide upregulates the expression of STIM1 and Orai1 by de novo synthesis by a mechanism that involves NFkB, c-Fos, and ROS via MAPK/ERK signaling.

Fibroblast growth factor 10 ameliorates renal ischaemia–reperfusion injury by attenuating mitochondrial damage

“…27 In addition, the opening of mitochondrial KATP channels attenuates ROS generation and cytochrome C release. 28 It was postulated that the protective mechanisms of FGF10 were associated with mitochondrial KATP channels. To verify this result, we used a specific mitochondrial KATP antagonist, 5-HD, in conjunction with FGF10 treatment.…”

“…This prevents mitochondrial swelling and inhibits the opening of mitochondrial permeability transition pores during reperfusion 27 . In addition, the opening of mitochondrial KATP channels attenuates ROS generation and cytochrome C release 28 . It was postulated that the protective mechanisms of FGF10 were associated with mitochondrial KATP channels.…”