Innervation and Neuronal Control of the Mammalian Sinoatrial Node a Comprehensive Atlas.
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ABSTRACT:
SUBMITTER: Hanna P
PROVIDER: S-EPMC8284939 | biostudies-literature | 2021 Apr
REPOSITORIES: biostudies-literature
Publications
Innervation and Neuronal Control of the Mammalian Sinoatrial Node a Comprehensive Atlas.
Hanna Peter P Dacey Michael J MJ Brennan Jaclyn J Moss Alison A Robbins Shaina S Achanta Sirisha S Biscola Natalia P NP Swid Mohammed A MA Rajendran Pradeep S PS Mori Shumpei S Hadaya Joseph E JE Smith Elizabeth H EH Peirce Stanley G SG Chen Jin J Havton Leif A LA Cheng Zixi Jack ZJ Vadigepalli Rajanikanth R Schwaber James J Lux Robert L RL Efimov Igor I Tompkins John D JD Hoover Donald B DB Ardell Jeffrey L JL Shivkumar Kalyanam K
Circulation research 20210225 9
[Figure: see text]. ...[more]
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Project description:Bioelectrical impulses intrinsically generated within the sinoatrial node (SAN) trigger the contraction of the heart in mammals. Though discovered over a century ago, the molecular and cellular features of the SAN that underpin its critical function in the heart are uncharted territory. Here, we identify four distinct transcriptional clusters by single-cell RNA sequencing in the mouse SAN. Functional analysis of differentially expressed genes identifies a core cell cluster enriched in the electrogenic genes. The similar cellular features are also observed in the SAN from both rabbit and cynomolgus monkey. Notably, Vsnl1, a core cell cluster marker in mouse, is abundantly expressed in SAN, but is barely detectable in atrium or ventricle, suggesting that Vsnl1 is a potential SAN marker. Importantly, deficiency of Vsnl1 not only reduces the beating rate of human induced pluripotent stem cell - derived cardiomyocytes (hiPSC-CMs) but also the heart rate of mice. Furthermore, weighted gene co-expression network analysis (WGCNA) unveiled the core gene regulation network governing the function of the SAN in mice. Overall, these findings reveal the whole transcriptome profiling of the SAN at single-cell resolution, representing an advance toward understanding of both the biology and the pathology of SAN.
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Project description:RNA Sequencing of Mouse Sinoatrial Node Reveals an Upstream Regulatory Role for Islet-1 in Cardiac Pacemaker Cells Rationale: Treatment of sinus node disease with regenerative or cell-based therapies will require a detailed understanding of gene regulatory networks in cardiac pacemaker cells (PCs). Objective: To characterize the transcriptome of PCs using RNA sequencing, and to identify transcriptional networks responsible for PC gene expression. Methods and Results: We used laser capture micro-dissection (LCM) on a sinus node reporter mouse line to isolate RNA from PCs for RNA sequencing (RNA-Seq). Differential expression and network analysis identified novel SAN-enriched genes, and predicted that the transcription factor Islet-1 (Isl1) is active in developing pacemaker cells. RNA-Seq on SAN tissue lacking Isl1 established that Isl1 is an important transcriptional regulator within the developing SAN. Conclusions: (1) The PC transcriptome diverges sharply from other cardiomyocytes; (2) Isl1 is a positive transcriptional regulator of the PC gene expression program. There are 25 RNA-Sequencing Samples
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Project description:Emerging evidence from large animal models implicates Ca2+ regulation, particularly intracellular sarcoplasmic reticulum (SR) Ca2+ release, as essential for sinoatrial node (SAN) automaticity. However, despite the apparent importance of SR Ca2+ release to SAN cell function it is uncertain how SR Ca2+ release is controlled in SAN cells from mouse. Understanding mouse SAN SR Ca2+ release mechanism will allow improved understanding of results in studies on SAN from genetic mouse models of Ca2+ homeostatic proteins. Here we investigated the functional relationship between sarcolemmal Ca2+ influx and SR Ca2+ release at the level of single SAN cell, using simultaneous patch-clamp current recording and high resolution confocal Ca2+ imaging techniques. In mouse SAN cells, both Ca2+ channel currents and triggered SR Ca2+ transients displayed bell-shaped, graded function with the membrane potential. Moreover, the gain function for Ca2+-induced Ca2+ release (CICR) displayed a monotonically decreasing function with strong voltage dependence, consistent with a "local control" mechanism for CICR. In addition, we observed numerous discrete Ca2+ sparks at the voltage range of diastolic depolarization, in sharp contrast to the much lower frequency of sparks observed at resting potentials. We concluded that the "local control" mechanism of CICR is responsible for both local Ca2+ release during diastolic depolarization and the synchronized Ca2+ transients observed during action potential in SAN cells.
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