Peripheral Glial Response to Sensory Nerve Degeneration

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 DESCRIPTION (provided by applicant): The focus of this project is the peripheral non-myelinating glia that ensheath the majority of sensory axons. Unmyelinated axons are often damaged and/or lost in neuropathies. The non-myelinating glia are thought to play key roles in the repair, degeneration and/or regeneration of the affected nerves. We have chosen to focus on the response to degeneration of sensory axons, one feature common to many neuropathies. To gain a better understanding of the mechanisms involved in the glial response to axonal damage/degeneration, we developed an inducible model of peripheral sensory nerve degeneration in zebrafish. This model permits the conditional and selective ablation of peripheral sensory neurons and their axons. In our initial studies, we have found evidence that upon axon degeneration, peripheral glia are critical to the removal of axonal debris and recruitment of immune cells to sites of the involved nerves. The hypothesis that will be tested in this proposal is that axonal damage and degeneration induces glia to alter their gene expression, resulting in phagocytic behaviors and signaling to the immune system. In this application, we propose two aims: (1) identify genes involved in the response of peripheral glia to sensory neurodegeneration and (2) to validate the candidate genes identified in Aim 1. This will be achieved through transcriptome analysis of control and metronidazole- treated fish. Validation of candidate genes will be performed using qPCR, in situ hybridization and CRISPR/Cas9 mediated deletion analysis. Identification of involved genes will provide an important foundation for future investigations into the mechanisms by which peripheral glia react to death and degeneration of sensory circuits, and can be used as the starting points for directed studies in higher vertebrates, with the eventual goal of developing new directions in clinical efforts to treat this aspect of many debilitating sensory neuropathies.