Mouse anti-Human GNA13 monoclonal antibody, clone 7G7C6

Frizzleds (FZDs) are unconventional G protein-coupled receptors, which activate diverse intracellular signaling pathways via the phosphoprotein Disheveled (DVL) and heterotrimeric G proteins. The Interaction interplay of FZDs with DVL and G proteins is complex, involves different regions of FZD and the potential dynamics are poorly understood. In the present study, we aimed to characterize the function of a highly conserved tyrosine (Y250(2.39)) in the intracellular loop 1 (ILl) of human FZD(4). We have found Y250(2.39) to be crucial for DVL2 interaction and DVL2 translocation to the plasma membrane. Mutant FZD4-Y250(2.39)F, impaired in DVL2 binding, was defective in both beta-catenin-dependent and beta-catenin-independent WNT signaling induced in Xenopus laevis embryos. The same mutant maintained interaction with the heterotrimeric G proteins Gan and G alpha(13) and was able to mediate WNT-induced G protein dissociation and G protein-dependent YAP/TAZ signaling. We conclude from modeling and dynamics simulation efforts that Y250(2.39) is important for the structural integrity of the FZD-DVL, but not for the FZD-G protein interface and hypothesize that the interaction network of Y250(2.39) and H348(4.46) plays a role in specifying downstream signaling pathways induced by the receptor.

G-protein-coupled receptors (GPCRs) and their ligands function in the progression of human malignancies. G alpha(12) and G alpha(13), encoded by GNA12 and GNA13, respectively, are referred to as the GEP oncogene and are implicated in tumor progression. However, the molecular mechanisms by which G alpha(12/13) activation promotes cancer progression are not fully elucidated. Here, we demonstrate elevated expression of G alpha 12/13 in human ovarian cancer tissues. G alpha(12/13) activation did not promote cellular migration in the ovarian cancer cell lines examined. Rather, G alpha(12/13) activation promoted cell growth. We used a synthetic biology approach using chimeric G proteins and GPCRs activated solely by artificial ligands to selectively trigger signaling pathways downstream of specific G proteins. We found that G alpha(12/13) promotes proliferation of ovarian cancer cells by activating the transcriptional coactivator YAP, a critical component of the Hippo signaling pathway. Furthermore, we reveal that inhibition of YAP by short hairpin RNA or a specific inhibitor prevented the growth of ovarian cancer cells. Therefore, YAP may be a suitable therapeutic target in ovarian cancer.