Abstract
Numerous studies have revealed that Rap1 (Ras-proximate-1 or Ras-related protein 1), a small GTPase protein, plays a crucial role in mediating cAMP signaling in isolated cardiac tissues and cell lines. However, the involvement of Rap1 in the cardiac development in vivo is largely unknown. By injecting anti-sense morpholino oligonucleotides to knock down Rap1a and Rap1b in zebrafish embryos, and in combination with time-lapsed imaging, in situ hybridization, immunohistochemistry and transmission electron microscope techniques, we seek to understand the role of Rap1 in cardiac development and functions. At an optimized low dose of mixed rap1a and rap1b morpholino oligonucleotides, the heart developed essentially normally until cardiac contraction occurred. Morphant hearts showed the myocardium defect phenotypes, most likely due to disrupted myofibril assembly and alignment. In vivo heart electrocardiography revealed prolonged P-R interval and QRS duration, consistent with an adherens junction defect and reduced Connexons in cardiac myocytes of morphants. We conclude that a proper level of Rap1 is crucial for heart morphogenesis and function, and suggest that Rap1 and/or their downstream factor genes are potential candidates for genetic screening for human heart diseases.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Atrioventricular Block / metabolism
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Atrioventricular Block / pathology
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Embryo, Nonmammalian / drug effects
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Embryo, Nonmammalian / pathology
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Embryo, Nonmammalian / ultrastructure
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Gene Knockdown Techniques
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Heart Conduction System / abnormalities
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Heart Conduction System / diagnostic imaging
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Heart Conduction System / metabolism*
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Heart Conduction System / pathology*
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Humans
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Intercellular Junctions / metabolism
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Intercellular Junctions / ultrastructure
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Monomeric GTP-Binding Proteins / metabolism*
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Morpholinos / pharmacology
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Myofibrils / drug effects
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Myofibrils / metabolism*
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Myofibrils / pathology*
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Phenotype
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Sarcomeres / drug effects
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Sarcomeres / metabolism
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Sarcomeres / ultrastructure
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Suppression, Genetic*
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Time-Lapse Imaging
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Ultrasonography
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Zebrafish / embryology
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Zebrafish / metabolism*
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Zebrafish Proteins / metabolism*
Substances
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Morpholinos
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Zebrafish Proteins
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Monomeric GTP-Binding Proteins
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terf2ip protein, zebrafish
Grants and funding
This study was supported by grants from the National Basic Research Program of the Chinese Ministry of Science and Technology [973 Grant 2012CB944503 (to DL), 2007CB512100 (to XT) and 2012CB945101 (to BZ)]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.