Phosphatidylinositol-4,5-bisphosphate (PIP2) stabilizes the open pore conformation of the Kv11.1 (hERG) channel
Amarouch, Mohamed Yassine
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences . Biomedical Sciences
New York, N.Y.
Biophysical journal. - New York, N.Y.
, p. 1110-1118
University of Antwerp
Phosphatidylinositol-4,5-bisphosphate (PIP2) is a phospholipid that has been shown to modulate several ion channels, including some voltage-gated channels like Kv11.1 (hERG). From a biophysical perspective, the mechanisms underlying this regulation are not well characterized. From a physiological perspective, it is critical to establish whether the PIP2 effect is within the physiological concentration range. Using the giant-patch configuration of the patch-clamp technique on COS-7 cells expressing hERG, we confirmed the activating effect of PIP2. PIP2 increased the hERG maximal current and concomitantly slowed deactivation. Regarding the molecular mechanism, these increased amplitude and slowed deactivation suggest that PIP2 stabilizes the channel open state, as it does in KCNE1-KCNQ1. We used kinetic models of hERG to simulate the effects of the phosphoinositide. Simulations strengthened the hypothesis that PIP2 is more likely stabilizing the channel open state than affecting the voltage sensors. From the physiological aspect, we established that the sensitivity of hERG to PIP2 comes close to that of KCNE1-KCNQ1 channels, which lies in the range of physiological PIP2 variations.