scholarly journals Transactivación de receptores con actividad de cinasa de tirosina (RTK’s) por receptores acoplados a proteínas G

2004 ◽  
Vol 15 (1) ◽  
pp. 33-48 ◽  
Author(s):  
Enrique Sánchez-Lemus ◽  
José A Arias-Montaño
Keyword(s):  
Protein Kinases ◽  
G Protein ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
G Protein Coupled Receptors ◽  
Mitogen Activated Protein Kinases ◽  
Mitogen Activated Protein ◽  
G Protein Coupled

Los efectos de los factores de crecimiento y de ciertas hormonas se deben a la activación de receptores con actividad intrínseca de cinasa de tirosina (o RTK’s, por receptor tyrosine kinases), cuya estimulación inicia cascadas de señalización intracelular que regulan eventos transcripcionales esenciales para la proliferación y la diferenciación celulares. Entre los efectos debidos a la estimulación de los RTK’s, destaca la activación de la familia de cinasas de proteína activadas por mitógeno o MAPK’s (mitogen-activated protein kinases). Existen evidencias que indican que la estimulación de algunos receptores acoplados a proteínas G (o GPCR’s, por G protein-coupled receptors) resulta en la activación de RTK’s en ausencia de un ligando para estos últimos. Este proceso ha sido denominado transactivación, y depende de señales intracelulares inducidas por la estimulación de GPCR’s en las que participan tanto las subunidades a como los complejos bg de las proteínas G, así como fenómenos de fosforilación mediados por diferentes cinasas. En este artículo se revisan las características estructurales de ambos tipos de receptores (GPCR’s y RTK’s), los mecanismos responsables de su activación y los procesos involucrados en el fenómeno de transactivación de RTK’s por activación de GPCR’s.

scholarly journals A Network of Mitogen-Activated Protein Kinases Links G Protein-Coupled Receptors to the c-jun Promoter: a Role for c-Jun NH2-Terminal Kinase, p38s, and Extracellular Signal-Regulated Kinase 5

1999 ◽  
Vol 19 (6) ◽  
pp. 4289-4301 ◽  
Author(s):  
Maria Julia Marinissen ◽  
Mario Chiariello ◽  
Michael Pallante ◽  
J. Silvio Gutkind
Keyword(s):  
Signaling Pathway ◽  
Protein Kinases ◽  
G Protein ◽  
Intracellular Signaling ◽  
Temporal Integration ◽  
Regulatory Elements ◽  
G Protein Coupled Receptors ◽  
Mitogen Activated Protein Kinases ◽  
Mitogen Activated Protein ◽  
G Protein Coupled

ABSTRACT The expression of the c-jun proto-oncogene is rapidly induced in response to mitogens acting on a large variety of cell surface receptors. The resulting functional activity of c-Jun proteins appears to be critical for cell proliferation. Recently, we have shown that a large family of G protein-coupled receptors (GPCRs), represented by the m1 muscarinic receptor, can initiate intracellular signaling cascades that result in the activation of mitogen-activated protein kinases (MAPK) and c-Jun NH2-terminal kinases (JNK) and that the activation of JNK but not of MAPK correlated with a remarkable increase in the expression of c-jun mRNA. Subsequently, however, we obtained evidence that GPCRs can potently stimulate the activity of the c-jun promoter through MEF2 transcription factors, which do not act downstream from JNK. In view of these observations, we set out to investigate further the nature of the signaling pathway linking GPCRs to the c-jun promoter. Utilizing NIH 3T3 cells, we found that GPCRs can activate the c-jun promoter in a JNK-independent manner. Additionally, we demonstrated that these GPCRs can elevate the activity of novel members of the MAPK family, including ERK5, p38α, p38γ, and p38δ, and that the activation of certain kinases acting downstream from MEK5 (ERK5) and MKK6 (p38α and p38γ) is necessary to fully activate the c-jun promoter. Moreover, in addition to JNK, ERK5, p38α, and p38γ were found to stimulate the c-jun promoter by acting on distinct responsive elements. Taken together, these results suggest that the pathway linking GPCRs to the c-junpromoter involves the integration of numerous signals transduced by a highly complex network of MAPK, rather than resulting from the stimulation of a single linear protein kinase cascade. Furthermore, our findings suggest that each signaling pathway affects one or more regulatory elements on the c-jun promoter and that the transcriptional response most likely results from the temporal integration of each of these biochemical routes.

scholarly journals Ligand bias in receptor tyrosine kinase signaling

2020 ◽  
Vol 295 (52) ◽  
pp. 18494-18507
Author(s):  
Kelly Karl ◽  
Michael D. Paul ◽  
Elena B. Pasquale ◽  
Kalina Hristova
Keyword(s):  
G Protein ◽  
Receptor Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
G Protein Coupled Receptors ◽  
Operational Model ◽  
Tyrosine Kinase Signaling ◽  
Rtk Signaling ◽  
Ligand Bias ◽  
G Protein Coupled

Ligand bias is the ability of ligands to differentially activate certain receptor signaling responses compared with others. It reflects differences in the responses of a receptor to specific ligands and has implications for the development of highly specific therapeutics. Whereas ligand bias has been studied primarily for G protein–coupled receptors (GPCRs), there are also reports of ligand bias for receptor tyrosine kinases (RTKs). However, the understanding of RTK ligand bias is lagging behind the knowledge of GPCR ligand bias. In this review, we highlight how protocols that were developed to study GPCR signaling can be used to identify and quantify RTK ligand bias. We also introduce an operational model that can provide insights into the biophysical basis of RTK activation and ligand bias. Finally, we discuss possible mechanisms underpinning RTK ligand bias. Thus, this review serves as a primer for researchers interested in investigating ligand bias in RTK signaling.

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