The effect of RGS12 on PDGFbeta receptor signalling to p42/p44 mitogen activated protein kinase in mammalian cells.
We have previously shown that the PDGFbeta 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 PDGFbeta receptor-mediated signal transmission. Several lines of evidence were obtained to support functional interaction between the PDGFbeta 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 PDGFbeta 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 PDGFbeta receptor signalling. In airway smooth muscle cells, over-expressed recombinant RGS12 and the isolated PDZ/PTB domain N-terminus co-localised with PDGFbeta 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 PDGFbeta receptor in ASM cells.
Sambi
Balwinder S
BS
Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor St, Glasgow, G4 0NR, UK.
Hains
Melinda D
MD
Waters
Catherine M
CM
Connell
Michelle C
MC
Willard
Francis S
FS
Kimple
Adam J
AJ
Pyne
Susan
S
Siderovski
David P
DP
Pyne
Nigel J
NJ
D000818:Animals; D002478:Cells, Cultured; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D004789:Enzyme Activation; D006168:Guinea Pigs; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000502:physiology*; D009154:Mutation; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D020710:RGS Proteins / Q000235:genetics / Q000502:physiology*; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction
D020710:RGS Proteins; D020797:Receptor, Platelet-Derived Growth Factor beta; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3