Transcriptional regulation of neurogenesis in the olfactory epithelium

Abstract

1. The olfactory epithelium (OE) is a simple structure that gives rise to olfactory sensory neurons (OSNs) throughout life. 2. Numerous transcription factors (TFs) are expressed in regions of the OE which contain progenitor cells and OSNs. The function of some of these TFs in OSN development has been elucidated with the aide of transgenic knockout mice. 3. We review here the current state of knowledge on the role of TFs in OE neurogenesis and relate the expression of these TFs, where possible, to the well-documented phenotype of the cells as they progress through the OSN lineage from progenitor cells to mature neurons.

Fig. 1.

Neurogenesis in the OE (A). Three distinct cell types (HBCs, GBCs, and OSNs) are believed to comprise the OSN cell lineage. These cell types can be distinguished based on morphological and antigenic phenotypes, as well as, on their location in the OE with respect to the basal lamina. Currently, there are only three TFs (Mash1, Ngn1, NeuroD; mauve-colored font) that have been studied well enough to state which cells in the OSN lineage express each TF. (B) model of transcriptional regulation of neurogenesis in the OE. See text for discussion. →: enhance/promote; ⊥: repress/inhibit; ?: uncertain. Abbreviations: ACIII—adenylyl cyclase type III; BrdU—bromodeoxyuridine; DSL—Delta, Serrate, and LAG-2 family of Notch ligands; GAP43—43 kDa growth associated protein; GBCs—stem cell globose basal cell; GBCt—transit amplifying globose basal cell; GBCinp—immediate neuronal precursor globose basal cell; Golf—olfactory G protein; HBC—horizontal basal cell; NCAM-neural cell adhesion molecule; OcNc—olfactory cyclic nucleotide gated channel; OE—Olfactory Epithelium; OMP-olfactory marker protein; ORs—odorant receptors; OSNi—immature olfactory sensory neuron; OSNm—mature olfactory sensory neuron.