Abstract
BackgroundOpeners 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.ResultsQuantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and western blot experiments showed that diazoxide increased expression of STIM1 and Orai1 at the mRNA and protein levels, respectively, in adult rat cardiomyocytes. Immunofluorescence analyses revealed that 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). Confocal microscopy revealed that diazoxide also led to nuclear translocation of the transcription factors c-Fos and NFκB, which was also blocked by NAC or 5-HD. Finally, the MAPK pathway inhibitor UO126 attenuated diazoxide-induced upregulation of STIM1 and Orai1 expression.ConclusionsOur 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.
Highlights
Voltage and store-operated Ca2+ channels are the major routes of Ca2+ influx in mammalian cells [1]
We examined whether reactive oxygen species (ROS) and the MAPK/ ERK pathway are involved in the upregulation of Orai1 and stromal interaction molecule 1 (STIM1) proteins by Dzx, and tested the possibility that changes in the expression of store-operated C a2+ entry (SOCE) components depend on c-Fos and NF-κB transcription factors
Immunofluorescence imaging revealed that Dzx changed the distribution of STIM1 in cardiomyocytes relative to that seen under control conditions (Fig. 1c–g)
Summary
Voltage and store-operated Ca2+ channels are the major routes of Ca2+ influx in mammalian cells [1]. Ischemic preconditioning is an endogenous phenomenon whereby brief periods of ischemia and reperfusion result in subsequent protection from acute myocardial infarction [11]. It can be induced pharmacologically with mKATP channel openers, such as diazoxide (Dzx), leading to increases in mitochondrial reactive oxygen species (ROS) production [12,13,14]. Openers of mitochondrial adenosine triphosphate-dependent potassium (mKATP) channels like diazoxide increase reactive oxygen species (ROS) production in cardiac cells and reduce C a2+ 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 C a2+ entry (SOCE) STIM1 and Orai
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
