Dissecting phosphatidylinositol 4,5-bisphosphate activation and thermosensation in TRP channels

Abstract

Phosphatidylinositol 4,5-bisphosphate (PIP2) is able to regulate the activity of many ion channels, transporters and enzymes. In particular, the activation of several TRP channels has been shown to be PIP2-dependent. For the case of TRPM8, this activation is supposed to be possible through a direct the interaction between PIP2 and key positively charged residues present in the TRP Domain. Because of the high sequence similarity among Transient Receptor Potential (TRP) channels on their TRP Domain, that region has been proposed as a common PIP2 binding site. In this work, we have exchanged different segments of the C-terminal region between TRPM8 and TRPV1 trying to understand the role of PIP2 during temperature activation of the channel. A chimera dubbed TRPM8(CTV1686-752) is activated by PIP2 and is able to confer the phenotype of heat activation. PIP2 sensitivity disappears when charges R701 and K710 were neutralized. When the exchanged fragment reached a length of 11 amino acid TRPM8(CTV1741-752), temperature dependence disappears. Together, our findings suggest the existence of different activation domains for temperature, PIP2 and voltage. Here, we also provide a simple interpretation for Channel-PIP2 interaction using a refined full-atom molecular model of TRPV1, and PIP2 docking analysis. (Supported by Fondecyt Grants Nº 3060003 (GO), 1040254 (FG) and 103-0830 (RL))