Figure 3: Pirt enhances TRPM8 currents evoked by menthol and cold temperature. | Nature Communications

Figure 3: Pirt enhances TRPM8 currents evoked by menthol and cold temperature.

From: Pirt functions as an endogenous regulator of TRPM8

Figure 3

(a) Menthol dose–response curves of TRPM8-expressing cells transfected with (closed circles) or without Pirt (open circles). When 50, 200, 500 or 1,000 μM menthol was applied to TRPM8/Pirt and TRPM8 alone, respectively, the current density was significantly different (*P<0.05, n=7 and 7 at 50 μM, n=13 and 13 at 200 μM, n=17 and 17 at 500 μM; **P<0.01, n=37 and 34 at 1,000 μM; two-tailed unpaired Student’s t-test). The EC50 values for TRPM8+Pirt and TRPM8 alone were 87.31±1.3 and 150.94±3.57 μM, respectively. (b) Normalized concentration–response relationship. The TRPM8/Pirt curve was shifted to the left of TRPM8 alone, and the EC50 values were 89.85±7.36 and 147.75±7.19 μM, respectively. (c) Representative current traces of TRPM8 and TRPM8/Pirt with and without menthol. The left (C1 and C3) and right (C2 and C4) traces indicate TRPM8 alone and TRPM8/Pirt, respectively. The upper (C1 and C2) and lower (C3 and C4) traces indicate the absence and presence of menthol, respectively. The C5 trace indicates the voltage step protocol. (d) Voltage–current relationship curves of TRPM8 with (closed circles) and without (open circles) Pirt constructed from currents in the presence of menthol (1 mM) with background currents subtracted (TRPM8/Pirt, n=27, TRPM8 alone, n=28; *P<0.05; two-tailed unpaired Student’s t-test). (e) Cold-evoked current traces in the TRPM8/Pirt (top left) and TRPM8 alone (top right) groups. The bottom traces show the application of cold buffer 37–10 °C. Temperature thresholds were determined by the corresponding temperature point where the slope of current rise intercepted with the current baseline. (f) Left columns: cold temperature-evoked average current size of TRPM8 with (black bar) and without (white bar, n=16 per group) Pirt. Right columns: cold-evoked temperature threshold of TRPM8/Pirt (black bar) or TRPM8 alone (white bar, n=16 per group). *P<0.05, **P<0.01, two-tailed unpaired Student’s t-test. Error bars represent s.e.m.

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