title: Characterization of a novel KCNQ1 mutation for type 1 long QT syndrome and assessment of the therapeutic potential of a novel IKs activator using patient-specific induced pluripotent stem cell-derived cardiomyocytes.
abstract: BACKGROUND
  Type 1 long QT syndrome (LQT1) is a common type of cardiac channelopathy associated with loss-of-function mutations of KCNQ1. Currently there is a lack of drugs that target the defected slowly activating delayed rectifier potassium channel (IKs). With LQT1 patient-specific human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hiPSC-CMs), we tested the effects of a selective IKs activator ML277 on reversing the disease phenotypes.
  
  
  METHODS
  A LQT1 family with a novel heterozygous exon 7 deletion in the KCNQ1 gene was identified. Dermal fibroblasts from the proband and her healthy father were reprogrammed to hiPSCs and subsequently differentiated into hiPSC-CMs.
  
  
  RESULTS
  Compared with the control, LQT1 patient hiPSC-CMs showed reduced levels of wild type KCNQ1 mRNA accompanied by multiple exon skipping mRNAs and a ~50% reduction of the full length Kv7.1 protein. Patient hiPSC-CMs showed reduced IKs current (tail current density at 30 mV: 0.33±0.02 vs. 0.92±0.21, P<0.05) and prolonged action potential duration (APD) (APD 50 and APD90: 603.9±39.2 vs. 319.3±13.8 ms, P<0.005; and 671.0±41.1 vs. 372.9±14.2 ms, P<0.005). ML277, a small molecule recently identified to selectively activate KV7.1, reversed the decreased IKs and partially restored APDs in patient hiPSC-CMs.
  
  
  CONCLUSIONS
  From a LQT1 patient carrying a novel heterozygous exon7 deletion mutation of KCNQ1, we generated hiPSC-CMs that faithfully recapitulated the LQT1 phenotypes that are likely associated with haploinsufficiency and trafficking defect of KCNQ1/Kv7.1. The small molecule ML277 restored IKs function in hiPSC-CMs and could have therapeutic value for LQT1 patients.
authors.affiliation: National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. ma.dongrui@nhcs.com.sg.
authors.forename: Dongrui
authors.initials: D
authors.lastname: Ma
authors.affiliation: National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. wei.he.ming@nhcs.com.sg.|Cardiovascular & Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore, 169857, Singapore. wei.he.ming@nhcs.com.sg.
authors.forename: Heming
authors.initials: H
authors.lastname: Wei
authors.affiliation: National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. lujun1986@hotmail.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.affiliation: National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. huangdou1220@gmail.com.
authors.forename: Dou
authors.initials: D
authors.lastname: Huang
authors.affiliation: National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. liu.zhenfeng@nhcs.com.sg.
authors.forename: Zhenfeng
authors.initials: Z
authors.lastname: Liu
authors.affiliation: National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. loh.li.jun@nhcs.com.sg.
authors.forename: Li Jun
authors.initials: LJ
authors.lastname: Loh
authors.affiliation: National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. md.omedul.islam@nhcs.com.sg.
authors.forename: Omedul
authors.initials: O
authors.lastname: Islam
authors.affiliation: Cardiovascular & Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore, 169857, Singapore. reginald.liew@duke-nus.edu.sg.
authors.forename: Reginald
authors.initials: R
authors.lastname: Liew
authors.affiliation: National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. winston.shim.s.n@nhcs.com.sg.|Cardiovascular & Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore, 169857, Singapore. winston.shim.s.n@nhcs.com.sg.
authors.forename: Winston
authors.initials: W
authors.lastname: Shim
authors.affiliation: National Heart Research Institute Singapore, National Heart Centre Singapore, 5th Hospital Drive, Singapore, 169609, Singapore. stuart.cook@duke-nus.edu.sg.|Cardiovascular & Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore, 169857, Singapore. stuart.cook@duke-nus.edu.sg.|National Heart and Lung Institute, Imperial College, South Kensington Campus, London, SW7 2AZ, UK. stuart.cook@duke-nus.edu.sg.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Cook
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D002454:Cell Differentiation; D002460:Cell Line; D000067470:Cellular Reprogramming Techniques; D004562:Electrocardiography; D005260:Female; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology*; D051657:KCNQ1 Potassium Channel / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D032383:Myocytes, Cardiac / Q000166:cytology*; D018408:Patch-Clamp Techniques; D010880:Piperidines / Q000627:therapeutic use; D024642:Potassium Channels, Voltage-Gated / Q000187:drug effects* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D029597:Romano-Ward Syndrome / Q000235:genetics*; D017384:Sequence Deletion / Q000235:genetics; D013844:Thiazoles / Q000627:therapeutic use; D014105:Tosyl Compounds / Q000627:therapeutic use; D055815:Young Adult
chemical_list: C576869:(R)-N-(4-(4-methoxyphenyl)thiazol-2-yl)-1-tosylpiperidine-2-carboxamide; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human; D010880:Piperidines; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger; D013844:Thiazoles; D014105:Tosyl Compounds; C059983:potassium channel protein I(sk)