Id genes are essential for early heart formation

Abstract

Deciphering the fundamental mechanisms controlling cardiac specification is critical for our understanding of how heart formation is initiated during embryonic development and for applying stem cell biology to regenerative medicine and disease modeling. Using systematic and unbiased functional screening approaches, we discovered that the Id family of helix-loop-helix proteins is both necessary and sufficient to direct cardiac mesoderm formation in frog embryos and human embryonic stem cells. Mechanistically, Id proteins specify cardiac cell fate by repressing two inhibitors of cardiogenic mesoderm formation-Tcf3 and Foxa2-and activating inducers Evx1, Grrp1, and Mesp1. Most importantly, CRISPR/Cas9-mediated ablation of the entire Id (Id1-4) family in mouse embryos leads to failure of anterior cardiac progenitor specification and the development of heartless embryos. Thus, Id proteins play a central and evolutionarily conserved role during heart formation and provide a novel means to efficiently produce cardiovascular progenitors for regenerative medicine and drug discovery applications.[Keywords: cardiac progenitors; cardiac mesoderm specification; heartless; Id proteins; CRISPR/Cas9-mediated quadruple knockout; platform for cardiac disease modeling and drug discovery] Supplemental material is available for this article.

Crosstalk between the RNA Methylation and Histone-Binding Activities of MePCE Regulates P-TEFb Activation on Chromatin

“…For example, P-TEFb activation is required for cardiac muscle hypertrophy, which is a risk factor for mortality in heart diseases (Sano et al, 2002). In this context, it is intriguing that the ID1-4 genes were very recently shown to be essential for early mammalian heart formation (Cunningham et al, 2017). Therefore, it will be essential to determine the phenotypes associated with MePCE loss and gain of function at the organismal level.…”

PGC1/PPAR Drive Cardiomyocyte Maturation through Regulation of Yap1 and SF3B2

“…Since PGC1/PPARα signals promoted CM contractility, we sought to identify downstream genes regulating calcium han-dling. To do this, we performed a single-cell high-throughput functional assay with PSC-CMs (Cunningham et al, 2017;McKeithan et al, 2017;Yu et al, 2018) treated with PPARαspecific ligands as shown in Figure 6A. Single cell analysis of calcium handling revealed that ligand-treated PSC-CMs have shorter ( 30ms) calcium transient duration (CTD) as compared to vehicle treated cells (DMSO) ( Figure 6B and Figure 6C).…”

Patient-specific functional genomics and disease modeling suggest a role for LRP2 in hypoplastic left heart syndrome

“…Thus, we asked whether siRNA-mediated candidate gene KD affects hiPSC-CM proliferation (Figure 4A). 23 Indeed, siRNAs directed against all 10 candidate genes together caused a marked reduction of EdU+ cardiomyocytes (ACTN1+) and cardiac nuclei numbers (Figure 4B-E), concomitant with downregulation of cell cycle genes (Figure 4F). In addition, proliferation inhibitors ( TP53 ) and apoptosis markers were increased (Figure 4G).…”

“…hiPSC-derived cardiomyocytes were produced as previously described. 23, 24 Cardiomyocytes were plated in 384 wells and transfected with siRNAs (see Online Appendix). Two days after transfection, EdU was added to the media for 24 hours and fixed.…”