Fig. 10
Roles of GRK2- and GRK6-mediated receptor phosphorylation in the desensitization of β2AR and its transactivation of EGFRs. A–D Cells were treated with 10 μM of isoproterenol for 5 min and washed/rechallenged to induce desensitization. A HEK-293 cells were transfected with WT-β2AR or GRK2-KO-β2AR. ISO/GRK2-KO group was significantly different from other groups (p < 0.001, n = 3) except at 3 × 10−7 M isoproterenol. **p < 0.01 compared with ISO/Con-KD group (n = 3). B HEK-293 cells were transfected with WT-β2AR or GRK6-KO-β2AR. **p < 0.01, ***p < 0.001 compared with other experimental groups (n = 3). C HEK-293 cells were transfected with EGFR-GFP together with WT-β2AR or GRK2-KO-β2AR. The cell lysates were immunoprecipitated with FLAG beads. Co-IP/lysate and IP were immunoblotted with antibodies against GFP and FLAG. #p < 0.05 compared with the “+/WT” group; **p < 0.01 compared with other groups of the cells expressing WT-β2AR or GRK2-KO-β2AR except the “ + /WT” group (n = 3). D HEK-293 cells were transfected with EGFR-GFP together with WT-β2AR or GRK6-KO-β2AR. ##p < 0.01 compared with other groups of the cells expressing WT-β2AR or GRK6-KO-β2AR (n = 3). E HEK-293 cells were transfected with WT- or GRK2-KO-β2AR. Cells were pretreated with either vehicle or 10 ng/mL of EGF for 20 min. **p < 0.01, ***p < 0.001 when the EGF/WT group was compared with other groups of the cells expressing WT-β2AR and GRK2-KO-β2AR; ##p < 0.01, ###p < 0.001 when EGF/WT group was compared to Veh/GRK2-KO or EGF/GRK2-KO group (n = 3). F HEK-293 cells were transfected with WT- or GRK6-KO-β2AR. Cells were pretreated with either vehicle or 10 ng/mL of EGF for 20 min. ***p < 0.001 when the EGF/WT group was compared with other groups of the cells expressing WT-β2AR or GRK6-KO-β2AR (n = 3). (E) or GRK6-KO-β2AR (F). Cells were treated with 10 ng/mL of EGF for 20 min. **p < 0.01, ***p < 0.001 compared with Veh/WT group (n = 3)