Physiological analysis of synthesized and natural peptides to confirm the molecular target of cone snail neuroexcitatory peptides
Mentor:Joseph Schulz, Associate Professor of Biology, Occidental College
Neuroexcitatory (NEX) peptides are a recent discovery in the A-superfamily of cone snail venom peptides and are known to cause tetanic paralysis due to overstimulation of neurons. The precise mechanism and molecular target of cone snail NEX peptides remains unknown. Preliminary evidence suggests that NEX peptides activate the persistent sodium current, an inactivating sodium current, causing repetitive firing of motor neurons. We aim to use two methods to confirm our hypothesis: the zebrafish spinal motility assay and patch-clamp recording of GFP-labeled motor neurons. The zebrafish spinal motility assay quantitatively tracks motility of larval zebrafish spines induced by test reagents. After successfully culturing GFP-labeled motor neurons from transgenic HB9 larval zebrafish, patch-clamping will allow us to record ion currents and voltage across the membranes of single neurons in the presence of our NEX peptides. We have identified 3 NEX peptides from the fish-hunting cone snail, C. catus, to use for our studies; two natural active NEX peptides and one active peptide synthesized based on sequence data. We have also been able to maintain GFP-labeled motor neurons from zebrafish larvae as old as 60 hfp (hours post fertilization) in primary cell culture for use in patch-clamp recordings. Finding peptides that directly target the persistent sodium current will open various research opportunities and could lead to drug development for the treatment of spinal cord injury.