The effect of siRNA-mediated Shank3 knockdown on Immunocytochemistry staining and motility in dorsal root ganglia growth cones

Mutations of the Shank3 gene have consistently been identified as a risk factor for Autism Spectrum Disorder, and are associated with neurological abnormalities indicative of neural connectivity issues. This project aimed to elucidate the functions of Shank3 protein in the growth cone during neural development. It was hypothesised that in dorsal root ganglia growth cones, Shank would colocalise with Homer1b/c (a protein that regulates intracellular calcium responses to BDNF), that siRNA-mediated knockdown of Shank3 protein would reduce Shank expression, and that Shank3 knockdown would abolish growth cone turning responses to BDNF. Shank and Homer appeared to colocalise in the growth cone. However, Shank3 knockdown did not decrease protein expression, and cell culture issues required that turning assays be terminated. As such, this research infers a role of Shank protein in peripheral nervous development but is unable to clarify the specific implications of this for axon pathfinding. Directions for future research include addressing cell culture issues, and repeating knockdown and turning experiments on hippocampal cells known to express Shank3 in the growth cone.