Figure 2. The P2X₇ R578Q variant exhibits attenuated nucleotide-stimulated signaling and pore formation.

A and B, HEK293 cells expressing the P2X₇ R578Q variant exhibit attenuated ERK1/2 activation. We have previously found that treatment with 1 µg/mL PMA plus 1 µg/mL ionomycin promotes ERK1/2 activation (data not shown), and this co-treatment was used here as a positive control. The error bars represent the standard error of the mean. These data are representative of at least three experiments. C and D, HEK293 cells expressing the P2X₇ R578Q variant display decreased nucleotide-induced FosB/ΔFosB induction in comparison to wild-type P2X₇. We have previously found that treatment with 1 µg/mL PMA plus 1 µg/mL ionomycin stimulates FosB/ΔFosB induction (data not shown), and this co-treatment was used here as a positive control. The top band on the FosB immunoblot is full-length FosB and the lower bands are its truncated splice variant ΔFosB [27]. The error bars represent the standard error of the mean. These data are representative of at least three experiments. E, The P2X₇ R578Q variant displays drastically attenuated pore formation. These images are representative of at least three experiments. I = ionomycin.