RESUMO
Mutations in LMNA, which encodes the nuclear proteins Lamin A/C, can cause cardiomyopathy and conduction disorders. Here, we employ induced pluripotent stem cells (iPSCs) generated from human cells carrying heterozygous K219T mutation on LMNA to develop a disease model. Cardiomyocytes differentiated from these iPSCs, and which thus carry K219T-LMNA, have altered action potential, reduced peak sodium current and diminished conduction velocity. Moreover, they have significantly downregulated Nav1.5 channel expression and increased binding of Lamin A/C to the promoter of SCN5A, the channel's gene. Coherently, binding of the Polycomb Repressive Complex 2 (PRC2) protein SUZ12 and deposition of the repressive histone mark H3K27me3 are increased at SCN5A. CRISPR/Cas9-mediated correction of the mutation re-establishes sodium current density and SCN5A expression. Thus, K219T-LMNA cooperates with PRC2 in downregulating SCN5A, leading to decreased sodium current density and slower conduction velocity. This mechanism may underlie the conduction abnormalities associated with LMNA-cardiomyopathy.
Assuntos
Cardiomiopatia Dilatada/genética , Sistema de Condução Cardíaco/patologia , Lamina Tipo A/genética , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , Adolescente , Adulto , Cardiomiopatia Dilatada/patologia , Cardiomiopatia Dilatada/cirurgia , Linhagem Celular , Regulação para Baixo , Epigênese Genética , Feminino , Transplante de Coração , Humanos , Células-Tronco Pluripotentes Induzidas , Masculino , Pessoa de Meia-Idade , Mutação , Miocárdio/citologia , Miocárdio/patologia , Miócitos Cardíacos/patologia , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Proteínas de Neoplasias , Complexo Repressor Polycomb 2/metabolismo , Fatores de TranscriçãoRESUMO
The use of light for triggering skeletal and cardiac muscles allows lower invasiveness higher selectivity and unprecedented possibility to target individual cells or even subcellular compartments in a temporally and spatially precise manner. Because cells are in general transparent, this requires the development of suitable interfaces that bestow light sensitivity to living matter. In the present work, successfully demonstrated is the use of conjugated polymer films as transducer to optically enhance the contraction rate of a human and patient-specific cardiac in vitro cell model. By different experimental approaches, the coupling mechanism to the photothermal effect is assigned. This work extends the range of application of the polymer-mediated cell photostimulation phenomenon to cardiac muscle cells, opening up possible applications in cardiac therapy and for implementation of in vitro studies.