Dissection of the components for PIP₂ activation and thermosensation in TRP channels

Phosphatidylinositol 4,5-bisphosphate (PIP₂) plays a central role in the activation of several transient receptor potential (TRP) channels. The role of PIP₂ on temperature gating of thermoTRP channels has not been explored in detail, and the process of temperature activation is largely unexplained. In this work, we have exchanged different segments of the C-terminal region between cold-sensitive (TRPM8) and heat-sensitive (TRPV1) channels, trying to understand the role of the segment in PIP₂ and temperature activation. A chimera in which the proximal part of the C-terminal of TRPV1 replaces an equivalent section of TRPM8 C-terminal is activated by PIP₂ and confers the phenotype of heat activation. PIP₂, but not temperature sensitivity, disappears when positively charged residues contained in the exchanged region are neutralized. Shortening the exchanged segment to a length of 11 aa produces voltage-dependent and temperature-insensitive channels. Our findings suggest the existence of different activation domains for temperature, PIP₂, and voltage. We provide an interpretation for channel-PIP₂ interaction using a full-atom molecular model of TRPV1 and PIP₂ docking analysis.