Using iPS cells to investigate cardiac phenotypes in patients with Timothy Syndrome

Individuals with congenital or acquired prolongation of the QT interval, or long QT syndrome (LQTS), are at risk of life-threatening ventricular arrhythmia. LQTS is commonly genetic in origin but can also be caused or exacerbated by environmental factors. A missense mutation in the L-type calcium channel CaV1.2 leads to LQTS in patients with Timothy syndrome. To explore the effect of the Timothy syndrome mutation on the electrical activity and contraction of human cardiomyocytes, we reprogrammed human skin cells from Timothy syndrome patients to generate induced pluripotent stem cells, and differentiated these cells into cardiomyocytes. Electrophysiological recording and calcium (Ca2+) imaging studies of these cells revealed irregular contraction, excess Ca2+ influx, prolonged action potentials, irregular electrical activity and abnormal calcium transients in ventricular-like cells. We found that roscovitine, a compound that increases the voltage-dependent inactivation of CaV1.2 (refs 6–8), restored the electrical and Ca2+ signalling properties of cardiomyocytes from Timothy syndrome patients. This study provides new opportunities for studying the molecular and cellular mechanisms of cardiac arrhythmias in humans, and provides a robust assay for developing new drugs to treat these diseases.

[1]  H Reuter,et al.  Ion channels in cardiac cell membranes. , 1984, Annual review of physiology.

[2]  M. Keating,et al.  The long QT syndrome. A review of recent molecular genetic and physiologic discoveries. , 1996, Medicine.

[3]  C. Franzini-armstrong,et al.  Formation of junctions involved in excitation-contraction coupling in skeletal and cardiac muscle. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[4]  L Meijer,et al.  Biochemical and cellular effects of roscovitine, a potent and selective inhibitor of the cyclin-dependent kinases cdc2, cdk2 and cdk5. , 1997, European journal of biochemistry.

[5]  S. Priori,et al.  The long QT syndrome. , 1997, Current problems in cardiology.

[6]  M. Iino,et al.  Embryonic lethality and abnormal cardiac myocytes in mice lacking ryanodine receptor type 2 , 1998, The EMBO journal.

[7]  N. Klugbauer,et al.  Functional embryonic cardiomyocytes after disruption of the L-type alpha1C (Cav1.2) calcium channel gene in the mouse. , 2000, The Journal of biological chemistry.

[8]  H. Huikuri,et al.  Sudden death due to cardiac arrhythmias. , 2001, The New England journal of medicine.

[9]  I. Paakkari,et al.  Cardiotoxicity of new antihistamines and cisapride. , 2001, Toxicology letters.

[10]  James A Thomson,et al.  Human Embryonic Stem Cells Develop Into Multiple Types of Cardiac Myocytes: Action Potential Characterization , 2003, Circulation research.

[11]  S. Priori,et al.  CaV1.2 Calcium Channel Dysfunction Causes a Multisystem Disorder Including Arrhythmia and Autism , 2004, Cell.

[12]  P. C. Viswanathan,et al.  Genetics of acquired long QT syndrome. , 2005, The Journal of clinical investigation.

[13]  Frank B Sachse,et al.  Severe arrhythmia disorder caused by cardiac L-type calcium channel mutations. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[14]  Michael J. Ackerman,et al.  Mutation of an A-kinase-anchoring protein causes long-QT syndrome , 2007, Proceedings of the National Academy of Sciences.

[15]  Shulan Tian,et al.  Induced Pluripotent Stem Cell Lines Derived from Human Somatic Cells , 2007, Science.

[16]  M. Yazawa.  TRIC channels essential for Ca[2+] handling in intracellular stores , 2007 .

[17]  K. Elmslie,et al.  Roscovitine, a cyclin‐dependent kinase inhibitor, affects several gating mechanisms to inhibit cardiac L‐type (Ca(V)1.2) calcium channels , 2007, British journal of pharmacology.

[18]  R. Tsien,et al.  The Timothy syndrome mutation differentially affects voltage- and calcium-dependent inactivation of CaV1.2 L-type calcium channels , 2008, Proceedings of the National Academy of Sciences.

[19]  Takashi Aoi,et al.  Generation of Pluripotent Stem Cells from Adult Mouse Liver and Stomach Cells , 2008, Science.

[20]  B. Thiers.  Induction of Pluripotent Stem Cells from Adult Human Fibroblasts by Defined Factors , 2008 .

[21]  Mark E. Anderson,et al.  Proarrhythmic Defects in Timothy Syndrome Require Calmodulin Kinase II , 2008, Circulation.

[22]  M. Kirk,et al.  Mechanisms of cardiac arrhythmias and sudden death in transgenic rabbits with long QT syndrome. , 2008, The Journal of clinical investigation.

[23]  Dan M. Roden,et al.  Clinical practice. Long-QT syndrome. , 2008, The New England journal of medicine.

[24]  Yunyu Zhang,et al.  Wnt3a‐Induced Mesoderm Formation and Cardiomyogenesis in Human Embryonic Stem Cells , 2009, Stem cells.

[25]  Sean P. Palecek,et al.  Functional Cardiomyocytes Derived From Human Induced Pluripotent Stem Cells , 2009, Circulation research.

[26]  K. Elmslie,et al.  The Timothy syndrome mutation of cardiac CaV1.2 (L‐type) channels: multiple altered gating mechanisms and pharmacological restoration of inactivation , 2009, The Journal of physiology.

[27]  B. Z. Peterson,et al.  Roscovitine Binds to Novel L-channel (CaV1.2) Sites That Separately Affect Activation and Inactivation* , 2009, The Journal of Biological Chemistry.

[28]  Karl-Ludwig Laugwitz,et al.  Patient-specific induced pluripotent stem-cell models for long-QT syndrome. , 2010, The New England journal of medicine.