Development of the cardiac conduction system in zebrafish.
The cardiac conduction system (CCS) propagates and coordinates the electrical excitation that originates from the pacemaker cells, throughout the heart, resulting in rhythmic heartbeat. Its defects result in life-threatening arrhythmias and sudden cardiac death. Understanding of the factors involved in the formation and function of the CCS remains incomplete. By transposon assisted transgenesis, we have developed enhancer trap (ET) lines of zebrafish that express fluorescent protein in the pacemaker cells at the sino-atrial node (SAN) and the atrio-ventricular region (AVR), termed CCS transgenics. This expression pattern begins at the stage when the heart undergoes looping morphogenesis at 36 h post fertilization (hpf) and is maintained into adulthood. Using the CCS transgenics, we investigated the effects of perturbation of cardiac function, as simulated by either the absence of endothelium or hemodynamic stimulation, on the cardiac conduction cells, which resulted in abnormal compaction of the SAN. To uncover the identity of the gene represented by the EGFP expression in the CCS transgenics, we mapped the transposon integration sites on the zebrafish genome to positions in close proximity to the gene encoding fibroblast growth homologous factor 2a (fhf2a). Fhf2a is represented by three transcripts, one of which is expressed in the developing heart. These transgenics are useful tools for studies of development of the CCS and cardiac disease.
Institute of Molecular and Cell Biology, Singapore; Developmental Dynamics, Heart Science Centre, National Heart and Lung Institute, Imperial College London, London, United Kingdom.
Kar-Lai
KL
Poon
University of California Santa Barbara (UCSB), Santa Barbara, United States.
Michael
M
Liebling
Institute of Molecular and Cell Biology, Singapore.
Igor
I
Kondrychyn
Developmental Dynamics, Heart Science Centre, National Heart and Lung Institute, Imperial College London, London, United Kingdom.
Thomas
T
Brand
Institute of Molecular and Cell Biology, Singapore; Department of Biological Sciences, National University of Singapore, Singapore. Electronic address: vlad@imcb.a-star.edu.sg.
Vladimir
V
Korzh
D000818:Animals; D030801:Animals, Genetically Modified; D001283:Atrioventricular Node / Q000254:growth & development / Q000378:metabolism; D004251:DNA Transposable Elements / Q000235:genetics; D004742:Enhancer Elements, Genetic / Q000235:genetics; D005346:Fibroblast Growth Factors / Q000096:biosynthesis / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D006329:Heart Conduction System / Q000254:growth & development* / Q000378:metabolism; D009024:Morphogenesis / Q000235:genetics*; D012849:Sinoatrial Node / Q000254:growth & development / Q000378:metabolism; D015027:Zebrafish / Q000235:genetics* / Q000254:growth & development
D004251:DNA Transposable Elements; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D005346:Fibroblast Growth Factors
Atrio-ventricular canal; Cardiac conduction system; Fhf2a; Sino-atrial node