Project description:Abnormalities of ventricular action potential (AP) cause malignant cardiac arrhythmias and sudden cardiac death. Here, we sought to identify microRNAs (miRNAs) that regulate the human cardiac AP and asked whether their manipulation allows for therapeutic modulation of AP abnormalities. Quantitative analysis of the miRNA targetomes in human cardiac myocytes identified miR-365 as a primary miRNA to regulate repolarizing ion channels. AP recordings in patient-specific induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs) showed that elevation of miR-365 level significantly prolonged AP duration in hiPSC-CMs derived from a Short-QT syndrome (SQTS) patient, whereas specific inhibition of miR-365 normalized pathologically prolonged AP in Long-QT syndrome (LQTS) iPSC-CMs. Transcriptome analyses in human iPSC-CMs at bulk and single-cell level corroborated the key cardiac repolarizing channels as direct targets of miR-365, together with functionally synergistic regulation of additional AP-regulating genes by this miRNA. Whole-cell patch clamp experiments revealed miR-365-based regulation of repolarizing ionic currents. Finally, refractory period measurements in human myocardial slices substantiated the prolonging effect of miR-365 on AP duration also in adult human myocardial tissue. Our results delineate miR-365 to regulate human cardiac AP duration by targeting key factors of cardiac repolarization.
Project description:Abnormalities of ventricular action potential (AP) cause malignant cardiac arrhythmias and sudden cardiac death. Here, we sought to identify microRNAs (miRNAs) that regulate the human cardiac AP and asked whether their manipulation allows for therapeutic modulation of AP abnormalities. Quantitative analysis of the miRNA targetomes in human cardiac myocytes identified miR-365 as a primary miRNA to regulate repolarizing ion channels. AP recordings in patient-specific induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs) showed that elevation of miR-365 level significantly prolonged AP duration in hiPSC-CMs derived from a Short-QT syndrome (SQTS) patient, whereas specific inhibition of miR-365 normalized pathologically prolonged AP in Long-QT syndrome (LQTS) iPSC-CMs. Transcriptome analyses in human iPSC-CMs at bulk and single-cell level corroborated the key cardiac repolarizing channels as direct targets of miR-365, together with functionally synergistic regulation of additional AP-regulating genes by this miRNA. Whole-cell patch clamp experiments revealed miR-365-based regulation of repolarizing ionic currents. Finally, refractory period measurements in human myocardial slices substantiated the prolonging effect of miR-365 on AP duration also in adult human myocardial tissue. Our results delineate miR-365 to regulate human cardiac AP duration by targeting key factors of cardiac repolarization.
Project description:We report gene expression changes after knockdown of transcription factors in human iPSC-derived cardiac myocytes. In prior experiments we showed that transcription factors known to be important for cardiac development were frequently up-regulated (i.e., "responsive") after small molecule perturbations of cultured iPSC-derived cardiac myocytes. We used RNA sequencing to test whether siRNA-mediated knockdown of transcription factors with different perturbation-responsiveness and tissue-specificity profiles would lead to inappropriate up-regulation of non-myocyte gene sets in cardiac myocytes.
Project description:Abnormalities of ventricular action potential (AP) cause malignant cardiac arrhythmias and sudden cardiac death. Here, we sought to identify microRNAs (miRNAs) that regulate the human cardiac AP and asked whether their manipulation allows for therapeutic modulation of AP abnormalities. Quantitative analysis of the miRNA targetomes in human cardiac myocytes identified miR-365 as a primary miRNA to regulate repolarizing ion channels. AP recordings in patient-specific induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs) showed that elevation of miR-365 level significantly prolonged AP duration in hiPSC-CMs derived from a Short-QT syndrome (SQTS) patient, whereas specific inhibition of miR-365 normalized pathologically prolonged AP in Long-QT syndrome (LQTS) iPSC-CMs. Transcriptome analyses in human iPSC-CMs at bulk and single-cell level corroborated the key cardiac repolarizing channels as direct targets of miR-365, together with functionally synergistic regulation of additional AP-regulating genes by this miRNA. Whole-cell patch clamp experiments revealed miR-365-based regulation of repolarizing ionic currents. Finally, refractory period measurements in human myocardial slices substantiated the prolonging effect of miR-365 on AP duration also in adult human myocardial tissue. Our results delineate miR-365 to regulate human cardiac AP duration by targeting key factors of cardiac repolarization.
Project description:We report gene expression by RNAtag-seq after treatment with 75 different small molecule perturbations in culture of human iPSC-derived cardiac myocytes and genetically matched primary dermal fibroblasts. Perturbations were chosen from the SelleckChem Bioactive Library, among all molecules targeting any kinases or G-protein coupled receptors, and chosen to have as little overlap in annotated targets as possible. Based on these experiments (and others) we show that transcription factors important for cardiac development and cardiac myocyte identity maintenance were frequently up-regulated (i.e., "responsive") after small molecule perturbations of cultured iPSC-derived cardiac myocytes (i.e., responsive). We also show that the set of highly responsive transcription factors in fibroblasts are enriched for barriers to fibroblast reprogramming to iPSC.
Project description:Inducing cardiac myocytes to proliferate is considered a potential therapy to target heart disease, however, modulating cardiac myocyte proliferation has proven to be a technical challenge. The Hippo pathway is a kinase signaling cascade that regulates cell proliferation during the growth of the heart. Inhibition of the Hippo pathway increases the activation of the transcription factors YAP/TAZ, which translocate to the nucleus and upregulate transcription of pro-proliferative genes. The Hippo pathway regulates the proliferation of cancer cells, pluripotent stem cells, and epithelial cells through a cell-cell contact-dependent manner, however, it is unclear if cell density-dependent cell proliferation is a consistent feature in cardiac myocytes. Here, we used cultured human iPSC-derived cardiac myocytes (hiCMs) as a model system to investigate this concept. hiCMs have a comparable transcriptome to the immature cardiac myocytes that proliferate during heart development in vivo. Our data indicate that a dense syncytium of hiCMs can regain cell cycle activity and YAP expression and activity when plated sparsely or when density is reduced through wounding. We found that combining two small molecules, XMU-MP-1 and S1P, increased YAP activity and further enhanced proliferation of low-density hiCMs. Importantly, these compounds had no effect on hiCMs within a dense syncytium. These data add to a growing body of literature that link Hippo pathway regulation with cardiac myocyte proliferation and demonstrate that regulation is restricted to cells with reduced contact inhibition.
Project description:The nuclear acetyltransferase p300 is a dose-dependent and limiting regulator of cardiac hypertrophy. p300 regulates hypertrophy by controlling the expression of specific microRNAs.The objective of this study was to dissect the role of miR-142 during p300 regulated hypertophic growth in vitro and in vivo and to verify its targets. MiR142 and a non target control were overexpressed using lentivirus in primary culture of neonatal cardiac myocytes. Overexpression was checked 48 hour post transfection. Samples include miR142 OE and non target from three different experiments.