Molecular Mechanisms Directing Spine Outgrowth and Synaptic Partner Selection in Caenorhabditis elegans.

The development of the nervous system requires precise outgrowth, extension, and wiring of both axons and dendrites to generate properly functioning neural circuits. The molecular mechanisms that shape neurite development, in particular dendritic development, remain incompletely understood. Dendrites are often highly branched and coated with actin-filled, thorny protrusions, called dendritic spines, that allow for increased numbers of synaptic contacts with neighboring neurons. Disruptions in dendritic spine development have been implicated in many neurological disorders such as autism, schizophrenia, and Alzheimer's disease. Although the development of dendritic spines is vital for cognitive function, understanding the mechanisms driving their outgrowth and stabilization in vivo remains a challenge. Our recent work identifies the presence of dendritic spine-like structures in the nematode Caenorhabditis elegans and provides initial insights into mechanisms promoting spine outgrowth in this system. Specifically, we show that neurexin/nrx-1 is a critical molecular component in directing the development of synaptic connections and promoting spine outgrowth. Our investigation provides important insights into the molecular machinery that sculpt synaptic connectivity, and continuing efforts in this system offer the potential for identifying new mechanisms governing both synaptic partner selection and dendritic spine outgrowth.