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Tissue- and cell-type-specific manifestations of heteroplasmic mtDNA 3243A>G mutation in human induced pluripotent stem cell-derived disease model.

ABSTRACT: Mitochondrial DNA (mtDNA) mutations manifest with vast clinical heterogeneity. The molecular basis of this variability is mostly unknown because the lack of model systems has hampered mechanistic studies. We generated induced pluripotent stem cells from patients carrying the most common human disease mutation in mtDNA, m.3243A>G, underlying mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome. During reprogramming, heteroplasmic mtDNA showed bimodal segregation toward homoplasmy, with concomitant changes in mtDNA organization, mimicking mtDNA bottleneck during epiblast specification. Induced pluripotent stem cell-derived neurons and various tissues derived from teratomas manifested cell-type specific respiratory chain (RC) deficiency patterns. Similar to MELAS patient tissues, complex I defect predominated. Upon neuronal differentiation, complex I specifically was sequestered in perinuclear PTEN-induced putative kinase 1 (PINK1) and Parkin-positive autophagosomes, suggesting active degradation through mitophagy. Other RC enzymes showed normal mitochondrial network distribution. Our data show that cellular context actively modifies RC deficiency manifestation in MELAS and that autophagy is a significant component of neuronal MELAS pathogenesis.

SUBMITTER: Hamalainen RH

PROVIDER: S-EPMC3780874 | biostudies-other | 2013 Sep

REPOSITORIES: biostudies-other

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Tissue- and cell-type-specific manifestations of heteroplasmic mtDNA 3243A>G mutation in human induced pluripotent stem cell-derived disease model.

Hämäläinen Riikka H RH Manninen Tuula T Koivumäki Hanna H Kislin Mikhail M Otonkoski Timo T Suomalainen Anu A

Proceedings of the National Academy of Sciences of the United States of America 20130903 38

Mitochondrial DNA (mtDNA) mutations manifest with vast clinical heterogeneity. The molecular basis of this variability is mostly unknown because the lack of model systems has hampered mechanistic studies. We generated induced pluripotent stem cells from patients carrying the most common human disease mutation in mtDNA, m.3243A>G, underlying mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome. During reprogramming, heteroplasmic mtDNA showed bimodal segrega ...[more]

PMID: 24003133

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Project description:Background Optogenetics, using light-sensitive proteins, emerged as a unique experimental paradigm to modulate cardiac excitability. We aimed to develop high-resolution optogenetic approaches to modulate electrical activity in 2- and 3-dimensional cardiac tissue models derived from human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes. Methods and Results To establish light-controllable cardiac tissue models, opsin-carrying HEK293 cells, expressing the light-sensitive cationic-channel CoChR, were mixed with hiPSC-cardiomyocytes to generate 2-dimensional hiPSC-derived cardiac cell-sheets or 3-dimensional engineered heart tissues. Complex illumination patterns were designed with a high-resolution digital micro-mirror device. Optical mapping and force measurements were used to evaluate the tissues' electromechanical properties. The ability to optogenetically pace and shape the tissue's conduction properties was demonstrated by using single or multiple illumination stimulation sites, complex illumination patterns, or diffuse illumination. This allowed to establish in vitro models for optogenetic-based cardiac resynchronization therapy, where the electrical activation could be synchronized (hiPSC-derived cardiac cell-sheets and engineered heart tissue models) and contractile properties improved (engineered heart tissues). Next, reentrant activity (rotors) was induced in the hiPSC-derived cardiac cell-sheets and engineered heart tissue models through optogenetics programmed- or cross-field stimulations. Diffuse illumination protocols were then used to terminate arrhythmias, demonstrating the potential to study optogenetics cardioversion mechanisms and to identify optimal illumination parameters for arrhythmia termination. Conclusions By combining optogenetics and hiPSC technologies, light-controllable human cardiac tissue models could be established, in which tissue excitability can be modulated in a functional, reversible, and localized manner. This approach may bring a unique value for physiological/pathophysiological studies, for disease modeling, and for developing optogenetic-based cardiac pacing, resynchronization, and defibrillation approaches.

Dataset Information

Tissue- and cell-type-specific manifestations of heteroplasmic mtDNA 3243A>G mutation in human induced pluripotent stem cell-derived disease model.

Publications

Tissue- and cell-type-specific manifestations of heteroplasmic mtDNA 3243A>G mutation in human induced pluripotent stem cell-derived disease model.

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