RUI: Examining Molecular Players Integrating Autophagy and Neuronal Development and Maintenance

Southwestern Oklahoma State University, Weatherford OK

Investigators

Abstract

During embryonic development, nervous system cells grow and branch off to make specialized connections with other nerve cells (synapses). Synapses are essential for the cell-to-cell communication that nervous systems need to function properly, and are created after threadlike cellular projections, known as axons, reach another target cell. One step in synapse formation involves removing extra material from axons by a process called autophagy. The present research project examines the precise role of one key protein (UNC-33/CRMP-2) that is known from previous work to affect axon growth and maintenance. Experiments use the roundworm C. elegans because of the advantages it offers for genetic manipulation and live cell imaging. Genetic lesions will be introduced in the gene coding for UNC-33/CRMP2, and the hypothesis that this molecule simultaneously regulates autophagy and synapse development will be tested using sophisticated cellular imaging and analysis techniques. This study has the potential to contribute to a deeper understanding of the molecular mechanisms underlying the development of neuronal circuits, as well as to a better understanding of defects in the growth and maintenance of synapses that are characteristic of a range of neurological diseases including autism, schizophrenia, and anxiety disorders. Moreover, this research will be carried out with the assistance of, and support the training of, undergraduate students at Southwestern Oklahoma State University. This project includes a variety of outreach programs for local elementary and high schools, and educational engagement with the general public on topics related to brain development and function. Despite the wealth of information surrounding neurodevelopment and neuronal survival, it is still unclear why neuronal components shown to work at the level of axonal outgrowth and cytoskeleton stability bind to components of the autophagy machinery. Moreover, it is undetermined why autophagy gene products, first characterized in yeast as Atg1, 6, 8, 9, 13, 18, are enriched in the nervous system. To shed light on the link of autophagy and neuronal development and survival, the investigators propose to characterize the role of UNC-33 in neuronal autophagy. The nematode unc-33 gene encodes for conserved members of the CRMP/TOAD/Ulip/DRP family of proteins. In C. elegans, UNC-33 isoforms mediate axonal guidance and axonogenesis in neurons. Moreover, preliminary investigations show that unc-33 mutants have a defect in dauer larva formation, an arrested developmental stage that survives in harsh environments due to enhanced cellular autophagy. In this study, the investigators will test the hypothesis that autophagy and UNC-33 serve to protect against defects in neuronal development and/or neuronal stability. In aim 1, they will define the role of UNC-33 in autophagy in neurons. In aim 2, they will characterize the role of basal autophagy in the maintenance of long-lived cells such as neurons. In aim 3, they propose to uncover the mechanism underlying the synthetic lethality of unc-33; daf-2 double mutants. Together, these studies will advance understanding of both autophagy and neuronal development and maintenance; will significantly enhance undergraduate education and the integration of research in the classroom; and will promote outreach to local communities.