Fig. 3: HapA induces MEK and ERK phosphorylation via PAR1.
From: HapA protease targets PAR-1/2 to modulate ERK signalling and reduce cancer cell viability
A Schematic illustration of PAR-1 activation of MEK/ERK signalling pathway. PAR-1 activation induces conformational changes in its transmembrane domains, which favour the interaction of the receptor with heterotrimeric G proteins. In its inactive state, the Gαi/o subunit is bound to guanosine diphosphate (GDP). Activated GPCRs triggers a conformational change in the Gαi/o subunit, promoting the exchange of GDP for GTP. This nucleotide exchange results in dissociation of the Gαi/o subunit from the βγ complex. Coupling to Gαi/o inhibits adenylate cyclase (AC), suppressing the formation of c-AMP, and thereby activating MAPK signalling. B MCF-7 cells were transfected with the PAR-1 reporter construct and were treated with the supernatant from the wild-type V. cholerae (A1552 WT) or from the ΔhapA mutant (A1552 ΔhapA) strain at a concentration of 0.5% for 0, 20 and 40 minutes. Cells were collected, and protein extracts were analysed by SDS-PAGE and western blot for the expression of ERK, p-ERK, MEK and p-MEK. Vinculin was used as a loading control. The bottom part of the figure provides quantitative analysis of the experiment in MCF-7 cells with visualized bands for ERK, p-ERK (C), MEK and p-MEK (D) normalized by loading control. The experiments were performed in triplicates. A representative experiment is shown. (*) p-value < 0.05; (**) p-value < 0.01; (n.s) p-value > 0.05.
