The E2A splice variant E47 regulates the differentiation of projection neurons via p57(KIP2) during cortical development

Abstract

During corticogenesis, distinct classes of neurons are born from progenitor cells located in the ventricular and subventricular zones, from where they migrate towards the pial surface to assemble into highly organized layer-specific circuits. However, the precise and coordinated transcriptional network activity defining neuronal identity is still not understood. Here, we show that genetic depletion of the basic helix-loop-helix (bHLH) transcription factor E2A splice variant E47 increased the number of Tbr1-positive deep layer and Satb2-positive upper layer neurons at E14.5, while depletion of the alternatively spliced E12 variant did not affect layer-specific neurogenesis. While ChIP-Seq identified a big overlap for E12- and E47-specific binding sites in embryonic NSCs, including sites at the cyclin-dependent kinase inhibitor (CDKI) gene locus, RNA-Seq revealed a unique transcriptional regulation by each splice variant. E47 activated the expression of the CDKI through binding to a distal enhancer. Finally, overexpression of E47 in embryonic NSCs impaired neurite outgrowth, and overexpression of E47 by electroporation disturbed proper layer-specific neurogenesis and upregulated p57(KIP2) expression. Overall, this study identifies E2A target genes in embryonic NSCs and demonstrates that E47 regulates neuronal differentiation via p57(KIP2).

TCF3 alternative splicing controlled by hnRNP H/F regulates E-cadherin expression and hESC pluripotency

“…For example, one study using knockout mice deficient for E12 or E47 revealed that E47 is essential for developmental progression at the pre-pro-B-cell stage, whereas E12 is dispensable for early B-cell development, commitment, and maintenance (Beck et al 2009). In cortical neurogenesis, E47 is required for proper neuronal differentiation and layer-specific localization, whereas E12 is dispensable for early corticogenesis (Pfurr et al 2017). These reports suggest that TCF3 AS plays an important role in a variety of developmental processes.…”

Helix–loop–helix proteins and the advent of cellular diversity: 30 years of discovery

“…During embryogenesis, E47 promotes cortical plate neural development and, in adult neural precursor cells, represses an astrocyte-specific gene program. In contrast, the E-protein antagonist Id3 orchestrates BMP2-induced astrocyte differentiation (Pfurr et al 2017). Upon cortical brain injury, Id3 is induced by BMP2 to neutralize E47 activity and promote astrocyte differentiation (Bohrer et al 2015).…”

E proteins sharpen neurogenesis by modulating proneural bHLH transcription factors’ activity in an E-box-dependent manner

“…Genome-wide ChIP-seq studies have established that the preferential E-box motifs bound by ASCL1, E47 and NEUROG1 correspond respectively to CAGCTG ( Castro et al, 2011 ; Borromeo et al, 2014 ), CAGSTG (where S stands for C or G: Lin et al, 2010 ; Pfurr et al, 2017 ) and CADATG (where D stands for A, G or T: Seo et al, 2007 ; Madelaine and Blader, 2011 ). In light of these intrinsic preferences, we tested how E47 modulates the abilities of ASCL1 and NEUROG1 to bind to DNA and activate transcription in different E-box contexts ( Figure 6A and Figure 6—figure supplement 2A ).…”