Title

Regulation of pannexin1 channels by stomatin

Date of Completion

January 2012

Keywords

Biology, Neurobiology

Degree

Ph.D.

Abstract

The pannexin-1 (Panx1) channel is a large-conductance channel in the plasma membrane of many mammalian cells. Unregulated opening of the channel is detrimental to the cell. However, little is known about how the channel is kept mostly closed under physiological conditions. In this study, I analyzed the effect of stomatin on Panx1 channels in both HEK-293 cells transfected with stomatin and Panx1, and cultured astrocytes and hippocampal neurons. In transfected HEK-293 cells, stomatin inhibited Panx1-mediated whole-cell currents without altering either the total or the membrane surface Panx1 protein expression; stomatin coimmunoprecipitated with full-length Panx1 as well as a Panx1 fragment containing the fourth membrane-spanning domain and the cytosolic carboxyl terminal; and the inhibitory effect of stomatin on Panx1-mediated whole-cell currents was abolished by truncating Panx1 at a site in the cytosolic carboxyl terminal. In cultured astrocytes, inhibition of endogenous stomatin expression by small interfering RNA (siRNA) increased whole-cell membrane current that was sensitive to the specific Panx1 channel blocker 10 Panx1. Stomatin siRNA also increased apoptosis of both astrocytes and hippocampal neuron although this effect was independent of Panx1 channels. These observations establish stomatin as a novel regulator of Panx1 channels, and suggest that stomatin plays an important role in cellular functions by regulating Panx1 channels and, possibly, other channels. ^