We are studying how neurotransmitters are released to affect nearby neurons and how the neural circuits are established during development, by combining several techniques such as molecular biology, cell and tissue culture, gene transfection, electrophysiological recordings (single-vesicle amperometry and patch-clamp recordings), and live imaging (for calcium dynamics or FRET [fluorescence resonance energy transfer]-based reporters).
First, we utilize the neuroendocrine cell line and the rat hypothalamic-neurohypophysial system to study the protein structure-functional relationship involved in neurotransmitter release, i.e., Ca2+-regulated exocytosis. The sequential steps in regulated exocytosis have been resolved at the single-vesicle level by amperometry recordings. Our research interest has converged on the fusion pore, a critical kinetic intermediate in regulated exocytosis. We determine how different cellular signalings can regulate the dynamics of fusion pore. These results address why different cellular signalings can lead to different kinetics of neurotransmitter release.
Further, to explore the mechanisms underlying neural circuit development, we study the patterned spontaneous activity in the developing rat retina termed “retinal waves”. During a critical period, retinal waves occur periodically and propagate across a population of developing retinal neurons. Why and how retinal waves occur remains mysterious. Retinal waves are initiated by neurotransmitter release from presynaptic interneurons. Molecular perturbation of releasing machinery in presynaptic interneurons can alter the spatial-temporal patterns of retinal waves, further regulating visual circuit targeting. Our ultimate goal is to determine how the wave spatial-temporal patterns can affect the precise connections between retinas and central targets, which is important for understanding the general rules underlying neural circuit development.