title: Amiodarone Induces Overexpression of Similar to Versican b to Repress the EGFR/Gsk3b/Snail Signaling Axis during Cardiac Valve Formation of Zebrafish Embryos.
abstract: Although Amiodarone, a class III antiarrhythmic drug, inhibits zebrafish cardiac valve formation, the detailed molecular pathway is still unclear. Here, we proved that Amiodarone acts as an upstream regulator, stimulating similar to versican b (s-vcanb) overexpression at zebrafish embryonic heart and promoting cdh-5 overexpression by inhibiting snail1b at atrioventricular canal (AVC), thus blocking invagination of endocardial cells and, as a result, preventing the formation of cardiac valves. A closer investigation showed that an intricate set of signaling events ultimately caused the up-regulation of cdh5. In particular, we investigated the role of EGFR signaling and the activity of Gsk3b. It was found that knockdown of EGFR signaling resulted in phenotypes similar to those of Amiodarone-treated embryos. Since the reduced phosphorylation of EGFR was rescued by knockdown of s-vcanb, it was concluded that the inhibition of EGFR activity by Amiodarone is s-vcanb-dependent. Moreover, the activity of Gsk3b, a downstream effector of EGFR, was greatly increased in both Amiodarone-treated embryos and EGFR-inhibited embryos. Therefore, it was concluded that reduced EGFR signaling induced by Amiodarone treatment results in the inhibition of Snail functions through increased Gsk3b activity, which, in turn, reduces snail1b expression, leading to the up-regulation the cdh5 at the AVC, finally resulting in defective formation of valves. This signaling cascade implicates the EGFR/Gsk3b/Snail axis as the molecular basis for the inhibition of cardiac valve formation by Amiodarone.
authors.affiliation: Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan.
authors.forename: Hung-Chieh
authors.initials: HC
authors.lastname: Lee
authors.affiliation: Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan.
authors.forename: Hao-Chan
authors.initials: HC
authors.lastname: Lo
authors.affiliation: Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan.
authors.forename: Dao-Ming
authors.initials: DM
authors.lastname: Lo
authors.affiliation: Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan.
authors.forename: Mai-Yan
authors.initials: MY
authors.lastname: Su
authors.affiliation: Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan.
authors.forename: Jia-Rung
authors.initials: JR
authors.lastname: Hu
authors.affiliation: Division of Hematology/Oncology, Tri-Service General Hospital, National Defense Medical Centre, Taipei, Taiwan.
authors.forename: Chin-Chieh
authors.initials: CC
authors.lastname: Wu
authors.affiliation: Cardiovascular Center, National Taiwan University Hospital Yun Lin Branch, Yun Lin, Taiwan.
authors.forename: Sheng-Nan
authors.initials: SN
authors.lastname: Chang
authors.affiliation: Division of Hematology/Oncology, Tri-Service General Hospital, National Defense Medical Centre, Taipei, Taiwan.
authors.forename: Ming-Shen
authors.initials: MS
authors.lastname: Dai
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan.
authors.forename: Chia-Ti
authors.initials: CT
authors.lastname: Tsai
authors.affiliation: Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan.|Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan.
authors.forename: Huai-Jen
authors.initials: HJ
authors.lastname: Tsai
mesh_terms: D000638:Amiodarone / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018773:Genes, erbB-1 / Q000235:genetics; D000071679:Glycogen Synthase Kinase 3 beta / Q000235:genetics / Q000378:metabolism; D006351:Heart Valves / Q000166:cytology* / Q000187:drug effects; D017403:In Situ Hybridization; D038081:Organogenesis / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D000071250:Snail Family Transcription Factors / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D014665:Vasodilator Agents / Q000494:pharmacology; D053675:Versicans / Q000494:pharmacology*; D015027:Zebrafish / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000071250:Snail Family Transcription Factors; D014665:Vasodilator Agents; D029961:Zebrafish Proteins; D053675:Versicans; D000071679:Glycogen Synthase Kinase 3 beta; D000638:Amiodarone