Systems Biology of Neuronal Survival and Axonal Regeneration of Central and Peripheral Nervous Systems

In adult mammals neurons react differently to the lesions, depending on their belonging to the central (CNS) or peripheral nervous system (PNS). While CNS exhibits poor recovery after injury, the PNS has consistent regeneration capabilities, that allow nerve stump to regrow and re-innervate lost target at a rate of about 1mm per day. Despite the numerous studies contributing to elucidate fundamental molecular aspects of nervous system reaction to damage, still a complete understanding of the phenomena is missing; it is unclear how fine phosphoproteomic regulatory processes contribute to nerve regrowth. We aim to use antibodies microarrays to analyse CNS and PNS injury phosphoproteomic profiles and to reconstruct regulatory processes at the base of recovery. The optic nerve crush is a common model to study regeneration in central nervous system: in adult mammals, after optic nerve injury, retinal ganglion cells (RGCs) do not regenerate their axons and most of them die by apoptosis within a few days. Recently, several strategies that activate neuronal intracellular pathways were proposed to prevent such degenerative processes and to enhance the axonal regeneration. The rho-related small GTPase Rac1 is part of a complex, intracellular signaling network, mediating many effects in neurons, including axon growth and cell survival; however, its role in neuronal survival and regeneration in vivo has not yet been properly investigated.
To address this point we intravitreally injected selective cell-penetrating Rac1 mutants after optic nerve crush and studied the effect on RGC survival and axonal regeneration. Results showed that mutants were able to improve survival, to prevent dendrite degeneration, and also improved regeneration by Pak1 activation on RGCs and ERK1/2 activation on glial cells. Furthermore, to contribute to the reconstruction of the underlying regulatory pathway, antibodies microarrays have been hybridized with optical nerve samples from control and lesioned tissues at 4 and 15 days. The project will progress in the identification of significant phosphoproteomic regulation that will elucidate the observed neuronal survival and axonal regeneration.

The kinetic of peripheral nervous system will likewise be studied at different time points, up stream and downstream the nerve crush site, and to compare results to similar data from CNS nerve crush model. Also this analysis will be lead through inferential and descriptive statistics of the data, signal transduction networks reconstruction and integration, data mapping and enrichment. Bioinformatic analysis will be part of a feedback process where findings will be verified by specific experiments involving in vitro and in vivo approaches, useful to further refine data interpretation and processing.

Contacts

For more information about this project, please, contact Prof. Mario Buffelli and Dr. Simone Zorzan