Figure 1.

Impaired Gα_q/11 signaling, but not Gα_s, Gα_i/o, or Gβγ signaling, diminishes UVR-induced Ca²⁺ responses in HEMs. (A) HEMs treated with the Gα_s signaling inhibitor CTX (500 ng/ml), the Gα_i/o inhibitor PTX (500 ng/ml), or vehicle (water) have similar retinal-dependent Ca²⁺ responses (F_norm) to 150 mJ/cm² UVR. Each trace was normalized to the response elicited by ionomycin (iono., 1 µM), added at the end of each experiment. n = 7–10 cells from one experiment averaged for each trace. (B) The mean peak Ca²⁺ responses (F_norm,max) elicited by 150 mJ/cm² UVR were not altered when HEMs were treated with CTX or PTX, as compared with vehicle control. n = 7 experiments per condition, ±SEM (error bars). (C) HEMs stimulated with 150 mJ/cm² UVR and treated with the Gβγ peptide inhibitor mSIRK (10 µM) or its inactive analogue L9A (10 µM) had similar retinal-dependent Ca²⁺ responses (F_norm). n = 6–10 cells from one experiment averaged for each trace. (D) Mean UVR-induced (150 mJ/cm²) peak retinal-dependent Ca²⁺ responses (F_{norm, max}) were not significantly different in HEMs treated with the Gβγ peptide inhibitor mSIRK versus its inactive analogue L9A. n = 9 paired experiments. (E) HEMs expressing RGS2 exhibited reduced retinal-dependent Ca²⁺ responses (F_norm) to 150 mJ/cm² UVR compared with control (mCherry-transfected) cells. n = 3–11 cells from one experiment averaged for each trace. (F) In paired experiments the mean amplitude of the retinal-dependent Ca²⁺ responses (F_norm,max) in RGS2-expressing HEMs stimulated with UVR (150 mJ/cm²) was diminished compared with control cells. n = 8 experiments per condition, P < 0.004. (G) qPCR analysis of mRNA levels of Gα_q/11 family members (Gα_q, Gα₁₁, Gα₁₄, and Gα₁₅) in HEMs, relative to actin. Bars represent mean ± SEM (error bars) from n = 3 independent experiments.