Modes and Regulation of Endocytic Membrane Retrieval in Mouse Auditory Hair Cells

• DOI: 10.1523/jneurosci.3313-13.2014
• Publication Date: 2014-01-15T18:11:24Z
• Authors: Jakob Neef; SangYong Jung; Aaron B. Wong; Kirsten Reuter; Tina Pangršič; Rituparna Chakrab...; Sebastian Kügler; Christine Lenz; Régis Nouvian; Rebecca M. Boumil; Wayne N. Frankel; Carolin Wichmann; Tobias Moser
• Keywords: Amphiphysin; Bulk endocytosis; Synaptic vesicle recycling; Ribbon synapse

Synaptic vesicle recycling sustains high rates of neurotransmission at the ribbon-type active zones (AZs) mouse auditory inner hair cells (IHCs), but its modes and molecular regulation are poorly understood. Electron microscopy indicated presence clathrin-mediated endocytosis (CME) bulk endocytosis. The endocytic proteins dynamin, clathrin, amphiphysin expressed broadly distributed in IHCs. We used confocal vglut1-pHluorin imaging membrane capacitance (Cm) measurements to study spatial organization dynamics IHC exocytosis Viral gene transfer IHCs targeted it synaptic vesicles. intravesicular pH was ∼6.5, supporting only a modest increase fluorescence during neutralization. Ca(2+) influx triggered an exocytic AZs, around which remained for several seconds. Cm decline proceeded with constant rate (linear component) after readily releasable pool (RRP). When exceeded three four RRP equivalents, additionally recruited faster (exponential that increased amount preceding likely reflects dynamin inhibitor Dyngo-4a clathrin blocker pitstop 2 selectively impaired linear component decline. A missense mutation 1 (fitful) inhibited similar extent as Dyngo-4a. propose use dynamin-dependent via CME support cycling mild stimulation recruit balance massive exocytosis.