Project description:It is established that E2A and its antagonist, Id3, modulate developmental progression at the pre-TCR and TCR checkpoints. Here we show at a global scale how E2A promotes commitment to the T cell lineage and how pre-TCR mediated signalling affects E2A genome-wide occupancy. We find aberrant development of CD4 memory-like and TFH-like cells, T-B cell conjugates and, remarkably, B cell follicles in Id3-/-thymi. We also find that Id3-/-CD4 splenocytes exhibit increased numbers of TFH-like cells. We propose a model in which Id3 modulates the naive versus effector/memory cell fate. Collectively, these data show how E2A acts globally to orchestrate T-lineage development and that Id3 antagonizes E2A activity beyond the pre-TCR checkpoint to enforce the naive T cell fate. ChIP-Seq was performed in thymocytes isolated from either untreated Rag2-/-mice (DN3 cells) or Rag2-/- mice injected with anti-CD3e antibody (DN4 cells). ChIP used antibodies against either E2A or H3K4me1.
Project description:Nodal signaling, mediated through SMAD transcription factors, is necessary for pluripotency maintenance and endoderm commitment. We have identified a new motif, termed SMAD Complex Associated (SCA) that is bound by SMAD2/3/4 and FOXH1 in human embryonic stem cells (hESCs) and derived endoderm. We demonstrate that two bHLH proteins - HEB and E2A - bind the SCA motif at regions overlapping SMAD2/3 and FOXH1. Further, we show that HEB and E2A associate with SMAD2/3 and FOXH1, suggesting they form a complex at critical target regions. This association is biologically important, as E2A is critical for mesendoderm specification, gastrulation, and Nodal signal transduction in Xenopus tropicalis embryos. Taken together, E2A is a novel Nodal signaling cofactor that associates with SMAD2/3 and FOXH1 and is necessary for mesendoderm differentiation. ChIP-seq of Smad2/3 and Input in X.tropicalis, stage 10.5 embryo.