Project description:Direct cardiac reprogramming converts fibroblasts into induced cardiomyocytes (iCMs) with the minimal combination of transcription factors, Gata4 (G), Mef2c (M), and Tbx5 (T). However, the induction of functional mature iCMs is inefficient and the mechanisms remain elusive. Mef2c is a central transcription factor in direct cardiac reprogramming. We investigated the effect of Mef2c isoforms(M1, M2, M6) and transcriptional activity (M2TAD) on cardiac reprogramming on cardiac reprogramming. Then, we found that the active form of Mef2c evoked epigenetic remodeling cooperating with p300 and promoted the maturation of iCMs.
Project description:Cardiac transcription factors (TFs) directly reprogram fibroblasts into induced cardiomyocytes (iCMs), where Mef2c acts as a pioneer factor with Gata4 and Tbx5 (GT). However, generation of functional and mature iCMs is inefficient and molecular mechanisms underlying this process remains largely unknown. Here we found that transduction of transcriptionally activated Mef2c via fusion of the powerful MyoD transactivation domain increased generation of beating iCMs by 30-fold in combination with GT.
Project description:Cardiac transcription factors (TFs) directly reprogram fibroblasts into induced cardiomyocytes (iCMs), where MEF2C acts as a pioneer factor with GATA4 and TBX5 (GT). However, the generation of functional and mature iCMs is inefficient, and the molecular mechanisms underlying this process remain largely unknown. Here, we found that the overexpression of transcriptionally activated MEF2C via fusion of the powerful MYOD transactivation domain combined with GT increased the generation of beating iCMs by 30-fold. Activated MEF2C with GT generated iCMs that were transcriptionally, structurally, and functionally more mature than those generated by native MEF2C with GT. Mechanistically, activated MEF2C recruited p300 and multiple cardiogenic TFs to cardiac loci to induce chromatin remodeling. In contrast, p300 inhibition suppressed cardiac gene expression, inhibited iCM maturation, and decreased the beating iCM numbers. Splicing isoforms of MEF2C with similar transcriptional activities did not promote functional iCM generation. Thus, MEF2C/p300-mediated epigenetic remodeling promotes iCM maturation.
Project description:We report the application of bioChIP-seq, bulk RNA-seq, Hi-C, H3K27ac HiChIP, and Massively parallel reporter assays (MPRAs) to characterize the p300-bound regulatory regions in murine cardiomyocytes (CMs). By obtaining ChIP-seq data of coactivator p300 from seven developmental stages of mouse CMs, we defined the dynamic p300 enhancers from embryonic CMs to adult CMs. We then validated the activity of dynamic p300 enhancers with AAV9-based MPRAs, we found dynamic p300 enhancers show dynamic activity from postnatal day 0 (P0) CMs to 4-week-old CMs. In addition, MRPA results suggest nuclear receptor motifs are required for the activity of some p300 late enhancers. With Hi-C and H3K27ac HiChIP data of E12.5, P0 and adult CMs, we identified chromatin structure changes such as chromatin loops, compartment switch, and new TAD boundaries are associated with dynamic p300 binding. This study provides data source of CM-selective p300 enhancers, chromatin 3D structure and gene expression during CM development and maturation.
Project description:The expression of genes is determined by the openness and accessibility of chromatin, which is the most basic phenomenon in the field of life sciences.The histone acetylase p300/CBP (CBP and P300 have similar structures and functions) can catalyze the acetylation of the lysine at the 27th position of histone H3(H3K27ac), which changes the the openness and accessibility of chromatin. Thus, p300/CBP are considered to be two of the most important transcription co-factors. To further understanding the role of p300/CBP in regulating calcium handing of prepubertal RV CMs, we first detected its expression in the prepubertal RV.The expressions of p300/CBP in the prepubertal dysfunctional RV were significantly downregulated, consistent with the data of p300-ChIP-seq, which showing the loss of p300 chromatin occupancy in calcium handing genes. Then we knocked out p300/CBP in neonatal mouse. p300/CBP knockout cardiomyocytes showed a impaired calcium handing ability, similar to that in prepubertal dysfunctional RV cardiomyocytes. These results confirmed the role of p300 in regulating the calcium handing ability of prepubertal RV CMs.
Project description:Cardiomyocytes and cardiac fibroblasts undergo coordinated maturation after birth, and cardiac fibroblasts are required for postnatal cardiomyocyte maturation in mice. Here, we investigate the role of cardiac fibroblast-expressed Growth Differentiating Factor 10 (GDF10) in postnatal heart development. In neonatal mice, Gdf10 is expressed specifically in cardiac fibroblasts, with its highest expression coincident with onset of cardiomyocytes cell cycle arrest and transition to hypertrophic growth. In neonatal rat ventricular myocyte cultures, GDF10 treatment promotes cardiomyocyte maturation indicated by increased binucleation, downregulation of cell cycle progression genes and upregulation of cell cycle inhibitor genes. GDF10 treatment leads to an increase in cardiomyocyte cell size together with increased expression of mature sarcomeric protein isoforms and decreased expression of fetal cardiac genes. RNAsequencing of GDF10-treated NRVM shows an increase in gene expression related to myocardial maturation, including upregulation of sodium and potassium channel genes. In vivo, loss of Gdf10 leads to a delay in myocardial maturation indicated by a decrease in cardiomyocyte cell size and binucleation as well as increased mitotic activity at postnatal (P) day 7. Further, induction of mature sarcomeric protein isoform gene expression is delayed, and expression of cell cycle progression genes is prolonged. However, by P10 indicators of cardiomyocyte maturation and mitotic activity are normalized in Gdf10-null hearts relative to controls. Together, these results implicate Gdf10 as a novel crosstalk mediator between cardiomyocytes and cardiac fibroblasts, required for appropriate timing of cardiomyocyte maturation steps including binucleation, hypertrophy, mature sarcomeric isoform switch and cell cycle arrest in the postnatal period.
Project description:We report the application of bioChIP-seq, bulk RNA-seq, Hi-C, and Massively parallel reporter assays (MPRAs) to characterize the p300-bound regulatory regions in murine cardiomyocytes (CMs). By obtaining ChIP-seq data of coactivator p300 from seven developmental stages of mouse CMs, we defined the dynamic p300 enhancers from embryonic CMs to adult CMs. We then validated the activity of dynamic p300 enhancers with AAV9-based MPRAs, we found dynamic p300 enhancers show dynamic activity from postnatal day 0 (P0) CMs to 4-week-old CMs. In addition, MRPA results suggest nuclear receptor motifs are required for the activity of some p300 late enhancers. With Hi-C data of E12.5, P0 and adult CMs, we identified chromatin structure changes such as chromatin loops, compartment switch, and new TAD boundaries are associated with dynamic p300 binding. This study provides data source of CM-selective p300 enhancers, chromatin 3D structure and gene expression during CM development and maturation.