Geling, A., Plessy, C., Rastegar, S., Strähle, U., and Bally-Cuif, L. (2004) Her5 acts as a prepattern factor that blocks neurogenin1 and coe2 expression upstream of Notch to inhibit neurogenesis at the midbrain-hindbrain boundary. Development 131(9): 1993-2006.
Neurogenesis in both vertebrates and invertebrates is tightly controlled in time and space involving both positive and negative regulators. We report here that the bHLH factor Her5 acts as a prepattern gene to prevent neurogenesis in the anlage of the midbrain/hindbrain boundary in the zebrafish neural plate. This involves selective suppression of both neurogenin1 (ngn1) and coe2 mRNA expression in a process that is independent of Notch signalling, and where inhibition of either ngn1 or coe2 expression is sufficient to prevent neuronal differentiation across the midbrain-hindbrain boundary. A ngn1 transgene faithfully responds to Her5 and deletion analysis of the transgene identifies an E-box in a ngn1 upstream enhancer to be required for repression by Her5. Together our data demonstrate a role of Her5 as a prepattern factor in the spatial definition of proneural domains in the zebrafish neural plate, in a manner similar to its Drosophila homologue Hairy.