We have previously shown that the PDGFβ receptor uses a classical GPCR-mediated pathway in order to induce efficient activation of p42/p44 MAPK in response to PDGF. We therefore, considered the possibility that GTPase accelerating proteins (RGS proteins), which regulate GPCR signalling, modulate PDGFβ receptor-mediated signal transmission. Several lines of evidence were obtained to support functional interaction between the PDGFβ receptor and RGS12 in HEK 293 and airway smooth muscle cells. Firstly, the over-expression of the RGS12 PDZ/PTB domain N-terminus or RGS12 PTB domain reduced the PDGF-induced activation of p42/p44 MAPK. Secondly, the RGS12 PDZ/PTB domain N-terminus and RGS12 PDZ domain can form a complex with the PDGFβ receptor. Therefore, the results presented here provide the first evidence to support the concept that the PDZ/PTB domain N-terminus and/or the PTB domain of RGS12 may modulate PDGFβ receptor signalling. In airway smooth muscle cells, over-expressed recombinant RGS12 and the isolated PDZ/PTB domain N-terminus co-localised with PDGFβ receptor in cytoplasmic vesicles. To provide additional evidence for a role of the PDZ/PTB domain N-terminus, we used RGS14. RGS14 has the same C-terminal domain architecture of an RGS box, tandem Ras-binding domains (RBDs) and GoLoco motif as RGS12, but lacks the PDZ/PTB domain N-terminus. In this regard, RGS14 exhibited a different sub-cellular distribution compared with RGS12, being diffusely distributed in ASM cells. These findings suggest that RGS12 via its PDZ/PTB domain N-terminus may regulate trafficking of the PDGFβ receptor in ASM cells.
- RGS proteins
- receptor trafficking
- PTB domain
- PDZ domain
- p42/44 mitogen activated protein kinase;
- PDGF beta receptor
Sambi, B. S., Hains, M., Waters, C., Connell, M., Willard, F. S., Kimple, A. J., ... Pyne, N. J. (2006). The effect of RGS12 on PDGFβ receptor signalling to p42/p44 mitogen activated protein kinase in mammalian cells. Cellular Signalling, 18, 971-981. https://doi.org/10.1016/j.cellsig.2005.08.003