Onset of odorant receptor gene expression during olfactory sensory neuron regeneration

Individual olfactory sensory neurons are thought to express only one odoran t receptor gene from a repertoire of hundreds to thousands of genes. How do these sensory neurons choose lust one specific odorant receptor to express during their differentiation? As an initial attempt toward understanding t he process of odorant receptor gene regulation, we studied when odorant rec eptor expression is activated during sensory neuron regeneration. We find t hat receptor gene expression is activated in postmitotic neurons and can oc cur in the absence of the olfactory bulb. These results suggest that recept or expression is restricted to the terminal stages of olfactory neuron diff erentiation, and sensory neurons do not simply inherit the odorant receptor that is already expressed in mitotic precursor cells. Our results also sup port a model in which odorant receptor gene expression occurs independent o f the olfactory bulb. (C) 2001 Academic Press.