Project description:Pitx2 is the homeobox gene located in proximity to the human 4q25 familial atrial fibrillation locus. Pitx2 haploinsufficient mice are prone to pacing induced atrial fibrillation indicating that reduced Pitx2 promotes an arrhythmogenic substrate within the atrium. Here, we inactivated Pitx2 in postnatal heart and discovered that unstressed adult Pitx2 mutant mice had sinus node dysfunction with impaired atrial conduction, an arrhythmia closely associated with atrial fibrillation. A genome-wide search for Pitx2 transcriptional targets using ChIP-sequencing and RNA expression profiling shows that Pitx2 represses target genes encoding cell junction proteins, ion channels, and critical transcriptional regulators many of which have been implicated in human atrial fibrillation by genome wide association studies. Our findings unveil a Pitx2 postnatal arrhythmogenic function, novel Pitx2 target genes relevant to atrial fibrillation, and reveal that Pitx2 stabilizes the intercalated disc in postnatal atrium. Genomic occupancy profiling of transcriptional factor Pitx2 in postnatal heart.
Project description:Pitx2 is the homeobox gene located in proximity to the human 4q25 familial atrial fibrillation locus. Pitx2 haploinsufficient mice are prone to pacing induced atrial fibrillation indicating that reduced Pitx2 promotes an arrhythmogenic substrate within the atrium. Here, we inactivated Pitx2 in postnatal heart and discovered that unstressed adult Pitx2 mutant mice had sinus node dysfunction with impaired atrial conduction, an arrhythmia closely associated with atrial fibrillation. A genome-wide search for Pitx2 transcriptional targets using ChIP-sequencing and RNA expression profiling shows that Pitx2 represses target genes encoding cell junction proteins, ion channels, and critical transcriptional regulators many of which have been implicated in human atrial fibrillation by genome wide association studies. Our findings unveil a Pitx2 postnatal arrhythmogenic function, novel Pitx2 target genes relevant to atrial fibrillation, and reveal that Pitx2 stabilizes the intercalated disc in postnatal atrium.
Project description:Pitx2 is the homeobox gene located in proximity to the human 4q25 familial atrial fibrillation locus. Pitx2 haploinsufficient mice are prone to pacing induced atrial fibrillation indicating that reduced Pitx2 promotes an arrhythmogenic substrate within the atrium. Here, we inactivated Pitx2 in postnatal heart and discovered that unstressed adult Pitx2 mutant mice had sinus node dysfunction with impaired atrial conduction, an arrhythmia closely associated with atrial fibrillation. A genome-wide search for Pitx2 transcriptional targets using ChIP-sequencing and RNA expression profiling shows that Pitx2 represses target genes encoding cell junction proteins, ion channels, and critical transcriptional regulators many of which have been implicated in human atrial fibrillation by genome wide association studies.
Project description:Pitx2 is the homeobox gene located in proximity to the human 4q25 familial atrial fibrillation locus. Pitx2 haploinsufficient mice are prone to pacing induced atrial fibrillation indicating that reduced Pitx2 promotes an arrhythmogenic substrate within the atrium. Here, we inactivated Pitx2 in postnatal heart and discovered that unstressed adult Pitx2 mutant mice had sinus node dysfunction with impaired atrial conduction, an arrhythmia closely associated with atrial fibrillation. A genome-wide search for Pitx2 transcriptional targets using ChIP-sequencing and RNA expression profiling shows that Pitx2 represses target genes encoding cell junction proteins, ion channels, and critical transcriptional regulators many of which have been implicated in human atrial fibrillation by genome wide association studies. Pitx2 control and mutant hearts were collected from 3-, 6- and 12-week-old mice. At each time point, three cotrols and three mutants were collected as biological replicates. cDNA microarray analysis was performed using Affymetrix GeneChip Mouse Genome 430 2.0 Array (Affymetrix, Santa Clara, CA).
Project description:Myocardial infarction results in compromised myocardial function with heart failure due to insufficient cardiomyocyte self-renewal. Unlike lower vertebrates, mammalian hearts only have a transient neonatal renewal capacity. Reactivating the primitive reparative ability in the fully mature heart requires an intimate knowledge of the molecular mechanisms promoting early heart repair. Here we identified a novel factor that can sufficiently promote heart muscle repair. By screening an established Hippo-deficient heart regeneration model for renewal promoting factors, we found that PITX2 protein expression in ventricles was induced after cardiomyocyte injury. Moreover, Pitx2-deficient neonatal hearts failed to repair after apex resection. Pitx2-gain-of-function in ventricular cardiomyocytes conferred reparative ability to the adult mouse heart after myocardial infarction. Integrated genomic analyses indicated that Pitx2 activated genes encoding electron transport chain components and reactive oxygen species scavengers. Pitx2 mutant myocardium had elevated reactive oxygen species levels while supplement of antioxidants suppressed the Pitx2-loss-of-function phenotype. Furthermore, PITX2 directly binds NFE2L2 and translocates from cytoplasm to nucleus upon oxidative stress.
Project description:The Pitx2 gene encodes a homeobox transcription factor that is required for mammalian development. Disruption of PITX2 expression in humans causes congenital heart diseases and is associated with atrial fibrillation (AF), however, the cellular and molecular processes dictated by Pitx2 during cardiac ontogeny remain unclear. To characterize the role of Pitx2 during murine heart development we sequenced over 75,000 single cardiac cell transcriptomes between two key developmental timepoints in control and Pitx2-null embryos. We uncovered that cardiac cell composition was dramatically altered in mutants at both E10.5 and E13.5. Interestingly, the differentiation dynamics of both anterior and posterior second heart field derived progenitor cells were disrupted in Pitx2 mutants. We also uncovered evidence for defects in left-right asymmetry within atrial cardiomyocyte populations. Furthermore, we were able to detail defects in cardiac outflow tract and valve development associated with Pitx2. Our findings offer insight into Pitx2 biology and provide a compilation of gene expression signatures for further detailing the complexities of heart development that will serve as the foundation for future studies of cardiac morphogenesis, congenital heart disease, and arrhythmogenesis.
Project description:The present study aimed at determining the differences in global mRNA expression between proliferating cardiomyocytes in the 2-day-old heart and growth arrested cardiomyocytes in 13-day-old heart of ICR mice. The transcriptomic profiles of the samples at the two time points(day 2 and day 13 of postnatal stage) were analyzed by direct comparison of the transcriptional level between the two groups of heart on the same custom 12×135K microarray (Roche NimbleGen)