Project Summary: Cortical projection neurons are integral to many of the most important capacities of neural circuitry, including sensation, motion, and higher-order cognition. These glutamatergic neurons cross extremely long distances -- up to 10,000s of times their cell body size! -- in order to connect remote neural networks. They enable, for example, direct communication between the two cerebral hemispheres or fine motor limb control via the spinal cord.

But how do growing projection neurons determine which path to take during development ? More specifically, how do the tips of growing axons -- called neuronal growth cones -- integrate  extracellular guidance cues with their own neuronal identity to consistently find their downstream targets in a complex and changing environment ? How do growth cones make pathfinding decisions when their nucleus, which contains the DNA of the neuron, is so far away ?

Aiming to answer some of these questions, a pioneering technical approach newly developed by the Macklis lab combines cellular labeling, biochemical fractionation, and organelle-resolution flow cytometry to provide a privileged window onto the internal molecular state of growth cones. These experiments have already revealed subtype-specific subcellular enrichment of molecular networks regulating cue response, which might underlie semi-autonomous decision making at the growth cone level.

Since localized networks of protein and RNA at growth cones likely exert direct control over neural circuitry formation, my MSc project aims to develop versatile tools inspired by recent findings of the Macklis lab enabling 1) targeted molecular trafficking specifically to growth cones and 2) local manipulation of molecular networks present in growth cones.