The lin-11 LIM homeobox gene specifies olfactory and chemosensory neuron fates in C-elegans

Chemosensory neuron diversity in C. elegans arises from the action of trans cription factors that specify different aspects of sensory neuron fate. In the AWB and AWA olfactory neurons, the LIM homeobox gene lim-4 and the nucl ear hormone receptor gene odr-7 are required to confer AWB and AWA-specific characteristics respectively, and to repress an AWC olfactory neuron-like default fate. Here, we show that AWA neuron fate is also regulated by a mem ber of the LIM homeobox gene family, lin-11. lin-11 regulates AWA olfactory neuron differentiation by initiating expression of odr-7, which then autor egulates to maintain expression. lin-11 also regulates the fate of the ASG chemosensory neurons, which are the lineal sisters of the AWA neurons. We s how that lin-11 is expressed dynamically in the AWA and ASG neurons, and th at misexpression of lin-11 is sufficient to promote an ASG, but not an AWA fate, in a subset of neuron types. Our results suggest that differential te mporal regulation of lin-11, presumably together with its interaction with asymmetrically segregated factors, results in the generation of the distinc t AWA and ASG sensory neuron types. We propose that a LIM code may be an im portant contributor to the generation of functional diversity in a subset o f olfactory and chemosensory neurons in C. elegans.