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. 2015 Dec 14;37(1):98–104. doi: 10.1038/aps.2015.110

Figure 1.

Figure 1

Pirt increases the TRPM8-mediated voltage-dependent currents via PIP2. (A) Representative current traces from TRPM8 stably expressed in HEK293 cells co-transfected with Pirt (Pirt+TRPM8+PIP2, n=21), where PIP2 (10 μmol/L) was added into the electrode pipette. Whole-cell inward currents evoked by 1 mmol/L menthol were analyzed using a series of 20-ms step pulses (−100 mV to +100 mV in 20 mV steps from −60 mV holding potential; the protocol is shown in Figure 1E). Before, background currents; after, currents elicited during menthol perfusion. (B) The net currents mediated by TRPM8 were calculated from (A). (C) I-V curves constructed from TRPM8-mediated net currents (after–before) for HEK293 cells stably expressing TPRM8 alone (TRPM8+PIP2, n=21, red line) or co-transfected with Pirt (Pirt+TRPM8+PIP2, n=21, black line). PIP2 (10 μmol/L) was added into the electrode pipette. (D) Menthol (1 mmol/L)-evoked inward current responses of HEK293 cells stably expressing TRPM8 alone (TRPM8+PIP2, n=21) were analyzed with the same protocol described in (A), where PIP2 (10 μmol/L) was added into the electrode pipette. (E) The net currents mediated by TRPM8 were calculated from (D). (F) I-V curves constructed from TRPM8-mediated net currents (after–before) for HEK293 cells stably expressing TPRM8 co-transfected with Pirt. PIP2 (10 μmol/L, Pirt+TRPM8+PIP2, n=21, black line) and PI (10 μmol/L, Pirt+TRPM8+PI, n=26, blue line, the representative current traces are not shown) were added into the electrode pipette. The reversal potentials for groups (C and F) of cells were close to 0 mV, characteristic of a TRPM8-mediated current. Each value is presented as the mean±SEM. bP<0.05, cP<0.01, unpaired t-test.