Transcriptome analysis of mouse and human sinoatrial node cells reveals a conserved genetic program

Abstract

The rate of contraction of the heart relies on proper development and function of the sinoatrial node, which consists of a small heterogeneous cell population, including Tbx3 + pacemaker cells. Here, we have isolated and characterized the Tbx3 + cells from Tbx3 +/Venus knock-in mice. We studied electrophysiological parameters during development and found that Venus-labeled cells are genuine Tbx3 + pacemaker cells. We analyzed the transcriptomes of late fetal FACS-purified Tbx3 + sinoatrial nodal cells and Nppb-Katushka + atrial and ventricular chamber cardiomyocytes, and identified a sinoatrial node-enriched gene program, including key nodal transcription factors, BMP signaling and Smoc2, the disruption of which in mice did not affect heart rhythm. We also obtained the transcriptomes of the sinoatrial node region, including pacemaker and other cell types, and right atrium of human fetuses, and found a gene program including TBX3, SHOX2, ISL1 and HOX family members, and BMP and NOTCH signaling components conserved between human and mouse. We conclude that a conserved gene program characterizes the sinoatrial node region and that the Tbx3 +/Venus allele provides a reliable tool for visualizing the sinoatrial node, and studying its development and function.

Nkx2-5 defines a subpopulation of pacemaker cells and is essential for the physiological function of the sinoatrial node in mice

“…2D,E, Fig. S4E), as reported previously (Liang et al, 2015;Puskaric et al, 2010;van Eif et al, 2019;Wiese et al, 2009). Thus, C0 and C1 correspond to the SAN cells.…”

“…We performed exo utero ECG on wild-type embryos from embryonic day 12.5 (E12.5) to E16.5 and found that the P waves, which accurately reflect atrial depolarization, became detectable at E12.5, and appeared typically from E13.5 onwards ( Fig. S2), consistent with a previous report that SAN cells begin to exhibit typical action potential (AP) configurations of pacemaking activity at E12.5 (van Eif et al, 2019). Therefore, we isolated the SAN and adjacent atrial tissues from E13.5 Nkx2.5 Cre/+ ;Shox2 HA-DsRed ;R26R YFP embryos.…”

“…The AP properties of the SAN head cells and atrial cells ( Fig. 1) exhibited typical configurations characterized previously for pacemaking and atrial cells (Sun et al, 2015;van Eif et al, 2019;Ye et al, 2015b;Zhang et al, 2002). However, the SAN junction cells presented unique AP configurations that were intermediate to those produced by the SAN head and atrial cells (Fig.…”

Mechanisms of Arrhythmias in the Brugada Syndrome

“…Meanwhile, as the newly formed chambers differentiate and acquire a secondary, or “working”, myocardial phenotype, the OFT myocardium retains its primary myocardial phenotype. While the properties of the working myocardium are associated with high expression of genes involved in respiratory-chain function, myofibril assembly, fast impulse conduction, and the contractile apparatus, primary myocardium marks nodal cells of the pacemaker and conduction system [ 38 ]. During fetal development, the RVOT differentiates into a more working myocardium phenotype, indicated by loss of expression of Tbx2 [ 39 ].…”

Silencing miR-370-3p rescues funny current and sinus node function in heart failure

“…We investigated the role of transcriptional regulators (transcription factors) and post-transcriptional regulators (microRNAs) in defining the level of HCN4. HCN4 mRNA levels are regulated by the transcription factors AP1 39 , Isl1 40,41 , Mef2c 39 , Nkx2.5 42 , NRSF 43 , Tbx3 44 and Tbx18 45 ; BMP2, BMP4 and Shox2 are sinus node specific transcription factors 46 . For example, the transcription factors, Tbx3 and Tbx18, are known to control the pacemaking phenotype of the sinus node and ectopic expression of Tbx3 and Tbx18 in working myocardium causes an upregulation of HCN4 and a switch to a sinus node phenotype 44,45 .…”