Mechanisms sustaining purinergic neurotransmission in non-vesicular channel synapses

2023 Fiscal Year Research-status Report

• Project/Area Number: 22K06833
• Research Institution: Kyoto Prefectural University of Medicine
• Principal Investigator: SHERWOOD MARK 京都府立医科大学, 医学(系)研究科(研究院), 助教 (60578160)
• Project Period (FY): 2022-04-01 – 2025-03-31
• Keywords: Channel-synapse / Synaptic-transmission / In-vivo recording / ATP-sensor / Intrinsic-NADH

Outline of Annual Research Achievements

Chemical synapses mediate rapid communication between excitable cells and are crucial to the function of the central and peripheral nervous systems. A novel chemical synapse, the ‘non-vesicular’ channel synapse employs conductive release of ATP (neurotransmitter) via large pore CALHM1/3 channels. To maintain synapse function, channel synapses must have stimulus-metabolic coupling to precisely match ATP production with demand. The current study is determining the molecular mechanism of stimulus-metabolic coupling at the channel-synapse. To this end we established in vivo functional imaging in taste cells.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

In this fiscal year we have continued to establish techniques for the functional imaging of taste cell function in vivo required for objective 3, i.e. in vivo two-photon imaging of intrinsic NADH fluorescence in taste cells.

In the previous fiscal year we generated mice expressing ATP-sensor on the surface of taste cells. This sensor is required to detect synaptically released ATP, as detailed in objective 4. This sensor has a high sensitivity for ADP and ATP. We therefore generated new high sensitivity biosensors that are specific for ATP.

Strategy for Future Research Activity

It is necessary to image synaptic release of ATP, however, at the time of in vivo imaging, it is impossible to know where the synapses are located within the tastebud. To solve this problem we perform four-dimensional imaging (XYZT) to capture the entire taste bud over time. The four-dimensional data generated is ill-suited to traditional region-of-interest based analysis. In the upcoming year (year-3) we will develop analysis tools for efficient ROI independent segmentation of synaptic ATP release from four-dimensional (XYZT) functional images of in vivo taste-buds.