Expression and localisation of two-pore domain (K2P) background leak potassium ion channels in the mouse retina

Two-pore domain (K2P) potassium channels perform essential roles in neuronal function. These channels produce background leak type potassium currents that act to regulate resting membrane potential and levels of cellular excitability. 15 different K2P channels have been identified in mammals and these channels perform important roles in a wide number of physiological systems. However, to date there is only limited data available concerning the expression and role of K2P channels in the retina. In this study we conduct the first comprehensive study of K2P channel expression in the retina. Our data show that K2P channels are widely expressed in the mouse retina, with variations in expression detected at different times of day and throughout postnatal development. The highest levels of K2P channel expression are observed for Muller cells (TWIK-1, TASK-3, TRAAK, and TREK-2) and retinal ganglion cells (TASK-1, TREK-1, TWIK-1, TWIK-2 and TWIK-3). These data offer new insight into the channels that regulate the resting membrane potential and electrical activity of retinal cells, and suggests that K2P channels are well placed to act as central regulators of visual signalling pathways. The prominent role of K2P channels in neuroprotection offers novel avenues of research into the treatment of common retinal diseases.