Rho deep in thought: Figure 1.

Neuronal communication underlies all aspects of brain function, including learning, memory, and consciousness. How neurons communicate is controlled by both the formation of neuronal connections during neural development and the regulation of neuronal activity in the adult brain. Rho GTPases have a well-known role in neuronal development, and recent studies published in iGenes Development/i (Steven et al. 2005; McMullan et al. 2006) have demonstrated that they also regulate neuronal activity in the adult brain—at least in iCaenorhabditis elegans/i. Rho in iC. elegans/i acts as part of a network of Gαsubq/sub pathways that increase neuronal activity by regulating both production and destruction of the second messenger diacylglycerol (DAG), which is a regulator of synaptic vesicle release. In this issue of iGenes Development/i, Williams et al. (2007) demonstrate that Gαsubq/sub acts via the UNC-73RhoGEF to increase Rho activity in neurons, and thus increase levels of DAG. The targets of DAG are known and, in one case, a pathway stretching from binding of ligand on the cell surface to changes in synaptic vesicle priming has been mapped out.