Synapse Formation
Establishment of the correct neural circuitry requires growing axons to recognize the appropriate cells as synaptic partners. The photoreceptors that mediate color vision provide us with a simple system in which to examine this process, as photoreceptors that respond to different wavelengths of light project to different target layers in the brain. We have found that the receptor tyrosine phosphatase LAR is required for ultraviolet-sensitive photoreceptors to form synapses with the correct partners, and that it signals by a novel mechanism in this process (Hofmeyer et al., PNAS 2006; Hofmeyer et al., PNAS 2009). We are interested in understanding the pathway upstream and downstream of LAR (Astigarraga et al., J. Neurosci. 2010). In addition, we are using a genetic screen to identify cell-surface molecules that provide targeting information to the color photoreceptors.

Another process that requires LAR is the dramatic growth of larval neuromuscular synapses during larval development. We have found that Barentsz, an RNA-binding protein, is also required for normal neuromuscular synapse growth. We would like to identify the targets of Barentsz post-transcriptional regulation and understand how they contribute to controlling synapse size.