Kwong-Man Ng1, Pamela Y Mok1, Amy W Butler1, Jenny C Y Ho1, Shing-Wan Choi1, Yee-Ki Lee1, Wing-Hon Lai1, Ka-Wing Au1, Yee-Man Lau1, Lai-Yung Wong1, Miguel A Esteban1, Chung-Wah Siu1, Pak C Sham1, Alan Colman1, Hung-Fat Tse2. 1. From Cardiology Division, Department of Medicine (K.-M.N., J.C.Y.H., Y.-K.L., W.-H.L., K.-W.A., Y.-M.L., L.-Y.W., C.-W.S., H.-F.T.) and Department of Psychiatry (A.W.B., S.-W.C., P.C.S., A.C.), Queen Mary Hospital, Research Center of Heart, Brain, Hormone and Healthy Aging, Li Ka Shing Faculty of Medicine (K.-M.N, C.W.-S., H.-F.T.), Hong Kong-Guangdong Joint Laboratory on Stem Cell and Regenerative Medicine (M.A.E., H.-F.T.), Centre for Genomic Sciences, Li Ka Shing Faculty of Medicine (P.C.S.), State Key Laboratory for Cognitive and Brain Sciences, Li Ka Shing Faculty of Medicine (P.C.S.), and Shenzhen Institutes of Research and Innovation (H.-F.T.), University of Hong Kong, Hong Kong SAR, China; Stem Cell Disease Models, A*STAR Institute of Medical Biology, Singapore (P.Y.M.); MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London, UK (A.W.B.); and Key Laboratory of Regenerative Biology of the Chinese Academy of Sciences and Guangdong Provincial Key Laboratory of Stem Cells and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Guangzhou, China (M.A.E.). 2. From Cardiology Division, Department of Medicine (K.-M.N., J.C.Y.H., Y.-K.L., W.-H.L., K.-W.A., Y.-M.L., L.-Y.W., C.-W.S., H.-F.T.) and Department of Psychiatry (A.W.B., S.-W.C., P.C.S., A.C.), Queen Mary Hospital, Research Center of Heart, Brain, Hormone and Healthy Aging, Li Ka Shing Faculty of Medicine (K.-M.N, C.W.-S., H.-F.T.), Hong Kong-Guangdong Joint Laboratory on Stem Cell and Regenerative Medicine (M.A.E., H.-F.T.), Centre for Genomic Sciences, Li Ka Shing Faculty of Medicine (P.C.S.), State Key Laboratory for Cognitive and Brain Sciences, Li Ka Shing Faculty of Medicine (P.C.S.), and Shenzhen Institutes of Research and Innovation (H.-F.T.), University of Hong Kong, Hong Kong SAR, China; Stem Cell Disease Models, A*STAR Institute of Medical Biology, Singapore (P.Y.M.); MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London, UK (A.W.B.); and Key Laboratory of Regenerative Biology of the Chinese Academy of Sciences and Guangdong Provincial Key Laboratory of Stem Cells and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Guangzhou, China (M.A.E.). hftse@hkucc.hku.hk.
Abstract
BACKGROUND: Danon disease is an X-linked disorder that leads to fatal cardiomyopathy caused by a deficiency in lysosome-associated membrane protein-2 (LAMP2). In female patients, a later onset and less severe clinical phenotype have been attributed to the random inactivation of the X chromosome carrying the mutant diseased allele. We generated a patient-specific induced pluripotent stem cell (iPSCs)-based model of Danon disease to evaluate the therapeutic potential of Xi-chromosome reactivation using a DNA methylation inhibitor. METHODS: Using whole-exome sequencing, we identified a nonsense mutation (c.520C>T, exon 4) of the LAMP2 gene in a family with Danon disease. We generated iPSC lines from somatic cells derived from the affected mother and her 2 sons, and we then differentiated them into cardiomyocytes (iPSC-CMs) for modeling the histological and functional signatures, including autophagy failure of Danon disease. RESULTS: Our iPSC-CM platform provides evidence that random inactivation of the wild-type and mutant LAMP2 alleles on the X chromosome is responsible for the unusual phenotype in female patients with Danon disease. In vitro, iPSC-CMs from these patients reproduced the histological features and autophagy failure of Danon disease. Administration of the DNA demethylating agent 5-aza-2'-deoxycytidine reactivated the silent LAMP2 allele in iPSCs and iPSC-CMs in female patients with Danon disease and ameliorated their autophagy failure, supporting the application of a patient-specific iPSC platform for disease modeling and drug screening. CONCLUSIONS: Our iPSC-CM platform provides novel mechanistic and therapeutic insights into the contribution of random X chromosome inactivation to disease phenotype in X-linked Danon disease.
BACKGROUND:Danon disease is an X-linked disorder that leads to fatal cardiomyopathy caused by a deficiency in lysosome-associated membrane protein-2 (LAMP2). In female patients, a later onset and less severe clinical phenotype have been attributed to the random inactivation of the X chromosome carrying the mutant diseased allele. We generated a patient-specific induced pluripotent stem cell (iPSCs)-based model of Danon disease to evaluate the therapeutic potential of Xi-chromosome reactivation using a DNA methylation inhibitor. METHODS: Using whole-exome sequencing, we identified a nonsense mutation (c.520C>T, exon 4) of the LAMP2 gene in a family with Danon disease. We generated iPSC lines from somatic cells derived from the affected mother and her 2 sons, and we then differentiated them into cardiomyocytes (iPSC-CMs) for modeling the histological and functional signatures, including autophagy failure of Danon disease. RESULTS: Our iPSC-CM platform provides evidence that random inactivation of the wild-type and mutant LAMP2 alleles on the X chromosome is responsible for the unusual phenotype in female patients with Danon disease. In vitro, iPSC-CMs from these patients reproduced the histological features and autophagy failure of Danon disease. Administration of the DNA demethylating agent 5-aza-2'-deoxycytidine reactivated the silent LAMP2 allele in iPSCs and iPSC-CMs in female patients with Danon disease and ameliorated their autophagy failure, supporting the application of a patient-specific iPSC platform for disease modeling and drug screening. CONCLUSIONS: Our iPSC-CM platform provides novel mechanistic and therapeutic insights into the contribution of random X chromosome inactivation to disease phenotype in X-linked Danon disease.
Authors: Alain van Mil; Geerthe Margriet Balk; Klaus Neef; Jan Willem Buikema; Folkert W Asselbergs; Sean M Wu; Pieter A Doevendans; Joost P G Sluijter Journal: Cardiovasc Res Date: 2018-12-01 Impact factor: 10.787