Guided migration of the immature neurons from their birthplace to the final destination constitutes the basis for ordered cytoarchitecture, specific synaptic connectivity, and complex function of the nervous system. Although considerable progress has been made in identifying the major migratory pathways and the genes and molecules involved in migration, the cellular mechanisms underlying the directed cell movement remain elusive. We hypothesize that neuronal migration can be regulated by second messengers, and different spatial and temporal patterns of these intracellular signals can exert distinct influences on the rate and direction of migration. To test this hypothesis, we have developed a glial-free culture system in which directional migration of single cerebellar granule neurons can be observed on glass coverslip in real time. This innovative culture system allows high-resolution quantitative imaging and intracellular manipulation of second messengers in different cellular regions of a single migrating neuron, thus enabling us to directly examine the role of second messengers in regulating neuronal migration. In this study, we will specifically determine how intracellular Ca2+ and its spatial and temporal patterns regulate the rate as well as the direction of granule cell migration using a combination of high-resolution Ca2+ imaging and spatially-restricted photoactivated release of caged Ca2+. Similarly, we will also determine the role of cAMP in regulating directed cell movement. A common scheme is the intracellular signals that not only intrinsically regulate directed cell movement but also mediate the actions of extracellular cues on neuronal migration. Our long-term goal is to elucidate the cellular mechanisms that control and regulate the migration of young neurons. These unique and innovative studies can generate a body of data upon which significant future research can be built to gain important insights towards the molecular and cellular mechanisms underlying neuronal migration, which is essential to our understanding of brain development as well as the development of potential treatments for brain disorders resulted from improper neuronal migration
