The TNF superfamily in neuronal development.

We will use a multidisciplinary approach to investigate the functions and mechanism of action of the TNFSF in the developing mouse nervous system. We will use well-characterized primary neuron culture systems to investigate whether the TNFSF cytokines we have already shown to promote or inhibit axon growth also affect dendrite growth and whether they are capable of influencing growth cone direction as either diffusible or cell surface ligands. We will use compartment cultures to determine wheth er localized receptor activation by individual cytokines has purely localized or generalized effects on neurite growth. We will use pharmacological inhibitors, expression of mutated signalling proteins and biochemical methods to delineate the signalling mechanisms by which these cytokines affect neurite growth and will use microarrays to identify NF-kB regulated genes required for promoting and/or inhibiting neurite growth. We will investigate appropriate phenotypic changes in neural processes and tissue innervation in transgenic mice to ascertain the physiological and developmental relevance of our in vitro observations. We will also investigate the roles of selected cytokines in neuronal survival and neuroblast development based on pilot data. Finally, will explore the roles of additional TNFSF cytokines selected on the basis of our comprehensive developmental profiling of TNFSF receptors.