ATP-gated cationic P2X receptors are widely expressed in neurons and are found on the membrane of hippocampal neurons. Many studies have demonstrated the physiological roles of P2X receptors in hippocampal neurotransmission and plasticity. Thus the electrophysiological properties of native and recombinant P2X channels have been extensively studied. However, little is known about the plasma membrane mobility of P2X channels since receptor mobility cannot be measured with electrophysiological methods. Diffusion of other ligand gated ion channels is known to underlie important physiological processes such as synaptic plasticity and thus P2X receptor mobility is likely an important mechanism in hippocampal physiology. The objective of our work was to develop an imaging approach to monitor P2X receptor mobility in the plasma membrane and to uncover the molecular factors that determine this mobility. Our preliminary data show that different P2X receptors exhibit different levels of mobility, that ATP quickens the rate of receptor mobility and that P2X2 mobility varies in different neuronal compartments. The specific goals of this proposal are 1) to use fluorescence recovery after photobleaching (FRAP) and single particle tracking (SPT) of Quantum dot labelled P2X2 receptees to probe the cellular settings in which P2X2 receptor mobility occurs in hippocampal neurons, 2) to use these measures of mobility to determine the molecular mechanisms that govern P2X2 mobility with a focus on proteins recently shown to interact with the C tail of P2X2.
The results of the research in this proposal are directly relevant to the mission of the NIH since they will lead to a better understanding of how an ion channel found in the brain contributes to hippocampal function, and in turn how the mobility of the channel is affected by neurotransmission in the hippocampus. This is most relevant to epilepsy where P2X2 channels are considered as new drug targets to treat this disease.
| Richler, Esther; Shigetomi, Eiji; Khakh, Baljit S (2011) Neuronal P2X2 receptors are mobile ATP sensors that explore the plasma membrane when activated. J Neurosci 31:16716-30 |
