Size Control in Neurons
Many degenerative disorders preferentially affect neurons with large axons/dendrites including Purkinje neurons, Betz cells, motoneurons, and sensory neurons. Thus, it’s plausible that defects in growth machinery that contribute to "extreme" neuron growth contribute to pathology in these diseases.
We are using genetic screens and comparative transcriptomics to identify factors required for growth and maintenance of axon/dendrite arbors in neurons with extreme growth demands.
Dendrite growth control: We recently identified a putative amino acid transporter, Pathetic (Path), that is required for growth in neurons with large dendrite arbors. Although Path is broadly expressed in neurons and non-neuronal cells, mutation of path impinges on nutrient responses and protein homeostasis specifically in neurons with large dendrite arbors. Path regulates translational capacity in neurons, and we are currently investigating whether Path can be engaged in other cell types to confer robustness on growth control.
Axon growth control:
Axon maintenance:
Compartmentalization in Dendrite Growth and Patterning
Axons and dendrites contain structurally and functionally distinct sub-compartments. Whereas axon/dendrite compartmentalization can be attributed to neuronal polarization, the developmental origin of sub-compartments in axons and dendrites is less well understood. To identify the developmental bases for compartment-specific growth and patterning in dendrites, we conducted a genetic screen for mutations that affect growth/patterning of discrete dendritic domains in Drosophila somatosensory neurons. From this screen, we identified mutants that selectively affected terminal dendrites, including terminal dendrite position along the proximal/distal axis, and patterning of terminal dendrites, suggesting that distance from the soma and branch type (major or terminal dendrite) are two key pieces of positional information in dendrite patterning.