Neurogenin1 is sufficient to induce neuronal differentiation of embryonal carcinoma P19 cells in the absence of retinoic acid.

1. Neurogenin1 (Ngn1) is a basic helix-loop-helix (bHLH) transcription factor that is expressed in neuronal precursors during development of the nervous system. 2. In the present work, we investigated a instructive potential of Ngn1 in pluripotent embryonal carcinoma P19 cells. Treatment with retinoic acid (RA) induced expression of Ngn1 as well as NeuroD in P19 cells in early period of neuronal differentiation. P19 cells contained endogenous E47, a heterodimeric partner of neurogenic bHLH factors, and overexpression of Ngn1 alone was sufficient to induce the maximum activation of the E-box-mediated gene expression. 3. Sustained expression of Ngn1 in the absence of RA was sufficient to induce substantial expression of neuronal markers. The data indicate that Ngn1 is able to commit pluripotent P19 cells to adopt a neural cell phenotype in the absence of RA, which may finally lead to enhanced neuronal differentiation. The results also suggest that RA may induce neuronal differentiation of P19 cells by promoting a bHLH cascade including Ngn1.