RESUMEN
Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. Ventricular dysfunction and cardiac arrhythmias are well-documented complications in patients with repaired TOF. Whether intrinsic abnormalities exist in TOF cardiomyocytes is unknown. We establish human induced pluripotent stem cells (hiPSCs) from TOF patients with and without DiGeorge (DG) syndrome, the latter being the most commonly associated syndromal association of TOF. TOF-DG hiPSC-derived cardiomyocytes (hiPSC-CMs) show impaired ventricular specification, downregulated cardiac gene expression and upregulated neural gene expression. Transcriptomic profiling of the in vitro cardiac progenitors reveals early bifurcation, as marked by ectopic RGS13 expression, in the trajectory of TOF-DG-hiPSC cardiac differentiation. Functional assessments further reveal increased arrhythmogenicity in TOF-DG-hiPSC-CMs. These findings are found only in the TOF-DG but not TOF-with no DG (ND) patient-derived hiPSC-CMs and cardiac progenitors (CPs), which have implications on the worse clinical outcomes of TOF-DG patients.
Asunto(s)
Síndrome de DiGeorge , Células Madre Pluripotentes Inducidas , Proteínas RGS , Tetralogía de Fallot , Humanos , Síndrome de DiGeorge/complicaciones , Síndrome de DiGeorge/genética , Tetralogía de Fallot/complicaciones , Arritmias Cardíacas/etiología , Miocitos CardíacosRESUMEN
Environmental perturbations induce transcriptional changes, some of which may be inherited even in the absence of the initial stimulus. Previous studies have focused on transfers through the germline although microbiota is also passed on to the offspring. Thus, we inspected the involvement of the gut microbiome in transgenerational inheritance of environmental exposures in Drosophila melanogaster. We grew flies in the cold versus control temperatures and compared their transcriptional patterns in both conditions as well as in their offspring. F2 flies grew in control temperature, while we controlled their microbiota acquisition from either F1 sets. Transcriptional status of some genes was conserved transgenerationally, and a subset of these genes, mainly expressed in the gut, was transcriptionally dependent on the acquired microbiome.
Asunto(s)
Adaptación Fisiológica/genética , Frío , Drosophila melanogaster/genética , Microbioma Gastrointestinal/genética , Patrón de Herencia/genética , Animales , Drosophila melanogaster/microbiología , Trasplante de Microbiota Fecal , Heces/microbiología , Perfilación de la Expresión Génica , MasculinoRESUMEN
Transcription activation involves RNA polymerase II (Pol II) recruitment and release from the promoter into productive elongation, but how specific chromatin regulators control these steps is unclear. Here, we identify a novel activity of the histone acetyltransferase p300/CREB-binding protein (CBP) in regulating promoter-proximal paused Pol II. We find that Drosophila CBP inhibition results in "dribbling" of Pol II from the pause site to positions further downstream but impedes transcription through the +1 nucleosome genome-wide. Promoters strongly occupied by CBP and GAGA factor have high levels of paused Pol II, a unique chromatin signature, and are highly expressed regardless of cell type. Interestingly, CBP activity is rate limiting for Pol II recruitment to these highly paused promoters through an interaction with TFIIB but for transit into elongation by histone acetylation at other genes. Thus, CBP directly stimulates both Pol II recruitment and the ability to traverse the first nucleosome, thereby promoting transcription of most genes.
Asunto(s)
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/enzimología , Nucleosomas/enzimología , Regiones Promotoras Genéticas , ARN Polimerasa II/metabolismo , Factores de Transcripción p300-CBP/metabolismo , Acetilación , Animales , Línea Celular , Cromatina/genética , Cromatina/metabolismo , Ensamble y Desensamble de Cromatina , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Regulación del Desarrollo de la Expresión Génica , Histonas/metabolismo , Nucleosomas/genética , Unión Proteica , ARN Polimerasa II/genética , Factor de Transcripción TFIIB/genética , Factor de Transcripción TFIIB/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transcripción Genética , Factores de Transcripción p300-CBP/genéticaRESUMEN
Polycomb Group (PcG) proteins are epigenetic repressors essential for control of development and cell differentiation. They form multiple complexes of which PRC1 and PRC2 are evolutionary conserved and obligatory for repression. The targeting of PRC1 and PRC2 is poorly understood and was proposed to be hierarchical and involve tri-methylation of histone H3 (H3K27me3) and/or monoubiquitylation of histone H2A (H2AK118ub). Here, we present a strict test of this hypothesis using the Drosophila model. We discover that neither H3K27me3 nor H2AK118ub is required for targeting PRC complexes to Polycomb Response Elements (PREs). We find that PRC1 can bind PREs in the absence of PRC2 but at many PREs PRC2 requires PRC1 to be targeted. We show that one role of H3K27me3 is to allow PcG complexes anchored at PREs to interact with surrounding chromatin. In contrast, the bulk of H2AK118ub is unrelated to PcG repression. These findings radically change our view of how PcG repression is targeted and suggest that PRC1 and PRC2 can communicate independently of histone modifications.