Enhanced expression of the transcription factor Sox11 was identified in developing sensory neurons of trigeminal and dorsal root ganglia of transgenic mice that overexpress neurotrophic growth factors in the skin. This expression suggested that Sox11 transcriptionally regulate genes involved in the enhanced neuron survival and axon projections exhibited by cutaneous sensory neurons in these animals. In adult DRG Sox11 was expressed at a low level but showed a significant increase following peripheral nerve crush. The high level of Sox11 expression during development and following adult neuron injury suggests Sox11 modulates a specific set of genes that have essential roles in neuron survival and axon growth. The experiments of this proposal will begin to define putative targets of Sox11 action and determine how its expression in adult neurons modulates their survival, axonal growth and response properties.
Three specific aims are proposed.
Aim 1 will use luciferase reporter assays to test if identified target genes involved in survival and axon growth are modulated by Sox11 expression.
Aim 2 will examine if the level of Sox11 expression in DRG cultures or following in vivo nerve injury correlates with the rate and quality of anatomical and functional recovery. In these studies we will manipulate Sox11 level using two approaches. To decrease expression in DRG neurons we will use a RNAi approach. To increase expression of Sox11 we will use non-replicating, neurotropic HSV viral vectors. Changes in Sox11 level may alter expression of genes involved in afferent sensitivity and pain signaling which could lead to behavioral sensitivity.
Aim 3 will test this possibility by measuring behavioral responses to applied thermal and mechanical stimuli. Relevance to Public Health: Impaired recovery following nerve injury can have significant effects on the quality of life and productivity of an individual due to abnormal nerve function or persistent pain following injury. Improved understanding of the cellular and molecular mechanisms that underlie survival and functional recovery of neurons following traumatic injury is required for design of effective strategies for recovery.
