We previously inferred using optical tweezers that a molecular clutch between the actin flow and N-cadherin adhesions could drive growth cone migration (Bard et al., J. Neurosci 2008), but we could not achieve a direct visualization of the engagement process. We have now combined primary neuronal cultures on N-cadherin coated micro-patterns with single molecule imaging at the ventral surface of growth cones. We reveal for the first time transient interactions on the order of seconds between the actin flow and N-cadherin adhesions in growth cones (arrowheads), reflecting a slipping clutch process at the individual molecular level (Garcia et al., PNAS 2015). see Video
In a second study involving more mature neurons, we revealed that engagement of a molecular clutch between trans-synaptic N-cadherin adhesions and the actin flow underlies the stabilization of dendritic filopodia into mature spines (Chazeau et al., Mol Biol Cell 2015). For example, stimulation of dendritic filopodia by N-cadherin coated beads or micropatterns induced the formation of stable spine-like structures enriched in actin-GFP (circle). This mechanism may have important implications in synaptic development and plasticity.