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. Author manuscript; available in PMC: 2016 May 27.
Published in final edited form as: Annu Rev Neurosci. 2015 Apr 22;38:331–349. doi: 10.1146/annurev-neuro-071714-034145

Figure 5.

Figure 5

Current model of olfactory, vomeronasal, and taste receptor gene regulation and effects on cell lineages. (a) Olfactory sensory neuron (OSN) precursor cells are committed to type I olfactory receptor (OR) expression or type-II OR expression by Lhx2. The zonal location in the main olfactory epithelium (MOE) of each OSN then restricts the pool of ORs among which it can choose for expression. Each OSN then stochastically selects an OR gene, giving rise to a field of mature OSNs expressing a single OR. (b) Vomeronasal precursor cells are committed to V1R or V2R expression by Bcl11b. Type I and type II vomeronasal sensory neurons (VSNs) then select a vomeronasal receptor (VR) for monogenic expression, with V2R-choosing cells also selecting a second V2R and in some cases an H2-Mv (see text). (c) Taste receptor cell (TRC) precursors are committed to sour lineage by Ascl1 and/or Prox1, to salt lineage by unknown factors, or to sweet/umami/bitter lineages by Skn-1a. Sweet/umami/bitter cells select one modality for their mature identity by unknown mechanisms. Bitter cells then further diversify, expressing heterogeneous sets of bitter taste receptors, which gives rise to the five TRC modalities as well as to subclasses of sour and bitter cells (see text).