Expression and function regulation of the sinoatrial ion channels

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Overall goal***This project aims to identify new key players in sinus node regulation of the electrical function based on a functional genomic approach. This knowledge could be used for further advancement in the understanding of molecular pathways underlying sinus node function.******Rationale***The sinoatrial node (SAN) cells exhibit spontaneous electrical activity due to a coordinated activation of a number of ion channels and their corresponding ionic currents. So far, transcriptional and post-transcriptional molecular regulation of these ion channels and their implication on SAN function remains unknown. To deal with this complex regulation, we developed an interdisciplinary strategy based on system biology approaches.******Objectives***The main goal of this project is to identify new regulators that can influence the ion channel expression responsible for SAN electrical function. Considering the significant contribution of the pacemaker (If) and L-type calcium (ICaL) currents to the automaticity of the SAN, the objectives of this study will be to identify transcription factors (TFs) and micro-RNAs (miRNAs) associated to ion channel expression that regulate SAN activity. These studies will be realized using a combination of genomic, bioinformatics, molecular and cell biology, as well as electrophysiological techniques and will be carried out in mouse- and human-derived cells. The following specific aims will be pursued.******Experimental plan***Aim 1. Identification of TFs and miRNAs specifically expressed in SAN***High-throughput differential expression studies will be performed to compare and determine the TFs and miRNAs that are expressed exclusively in the mouse SAN. A SAN preferential expression would support a role in the SAN electrical function.******Aim 2. Identification of the TFs and miRNAs that are potential regulators of HCN and calcium channels expression***Bioinformatics analysis will predict whether the identified TFs and miRNAs are able to bind SAN ion channel genes on the DNA promoter or mRNA 3'untranslated region, respectively.******Aim 3. Determine the contribution of the selected TFs and miRNAs in the regulation of SAN ion channel expression and function***Considering that the selected regulators can bind on ion channel genes regulatory sequences, we will also examine their potential contribution. First, we will study their effects on ion channel expressions in mouse neonatal cardiomyocytes and finally on ionic current regulation in hiPSCs-CM using knockdown strategies (siRNA and antagomir).******Expected Outcomes***This project will help uncover and identify new TFs and miRNAs that regulate SAN ion channel expression. Ultimately, these findings may help better understand the fundamental mechanisms that control the electrical activity of in the SAN.