In mammals, each olfactory sensory neuron randomly expresses one, and only one, olfactory receptor (OR)--a phenomenon called the "one-neuron-one-receptor" rule. Although extensively studied, this rule was never proven for all ~1,000 OR genes in one cell at once, and little is known about its dynamics. Here, we directly tested this rule by single-cell transcriptomic sequencing of 178 cells from the main olfactory epithelium of adult and newborn mice. To our surprise, a subset of cells expressed multiple ORs. Most of these cells were developmentally immature. Our results illustrated how the "one-neuron-one-receptor" rule may have been established: At first, a single neuron temporarily expressed multiple ORs--seemingly violating the rule--and then all but one OR were eliminated. This work provided experimental evidence that epigenetic regulation in the olfactory system selects a single OR by suppressing a few transiently expressed ORs in a single cell during development.
Keywords: immature and mature olfactory sensory neurons; odorant receptor; olfactory system; single‐cell RNA‐Seq; trace amine‐associated receptor (TAAR).
© 2015 The Authors. Published under the terms of the CC BY 4.0 license.