The expansion of GPCR transactivation-dependent signalling to include serine/threonine kinase receptors represents a new cell signalling frontier.
G protein-coupled receptor (GPCR) signalling is mediated through transactivation-independent signalling pathways or the transactivation of protein tyrosine kinase receptors and the recently reported activation of the serine/threonine kinase receptors, most notably the transforming growth factor-β receptor family. Since the original observation of GPCR transactivation of protein tyrosine kinase receptors, there has been considerable work on the mechanism of transactivation and several pathways are prominent. These pathways include the "triple membrane bypass" pathway and the generation of reactive oxygen species. The recent recognition of GPCR transactivation of serine/threonine kinase receptors enormously broadens the GPCR signalling paradigm. It may be predicted that the transactivation of serine/threonine kinase receptors would have mechanistic similarities with transactivation of tyrosine kinase pathways; however, initial studies suggest that these two transactivation pathways are mechanistically distinct. Important questions are the relative importance of tyrosine and serine/threonine transactivation pathways, the contribution of transactivation to overall GPCR signalling, mechanisms of transactivation and the range of cell types in which this phenomenon occurs. The ultimate significance of transactivation-dependent signalling remains to be defined but it appears to be prominent and if so will represent a new cell signalling frontier.
Diabetes Complications Laboratory, Discipline of Pharmacy, School of Medical Sciences and Diabetes Complications Group, RMIT University, Bundoora, VIC, 3083, Australia.
Danielle
D
Kamato
Muhamad Ashraf
MA
Rostam
Rebekah
R
Bernard
Terrence J
TJ
Piva
Nitin
N
Mantri
Daniel
D
Guidone
Wenhua
W
Zheng
Narin
N
Osman
Peter J
PJ
Little
D000818:Animals; D006801:Humans; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D015533:Transcriptional Activation; D054460:rho-Associated Kinases / Q000378:metabolism
D043562:Receptors, G-Protein-Coupled; D020794:Receptor Protein-Tyrosine Kinases; D054460:rho-Associated Kinases