Activation of JNK by Epac Is Independent of Its Activity as a Rap Guanine Nucleotide Exchanger
Guanine nucleotide exchange factors (GEFs) and their associated GTP-binding proteins (G-proteins) are key regulatory elements in the signal transduction machinery that relays information from the extracellular environment into specific intracellular responses. Among them, the MAPK cascades represent...
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00219258_v278_n36_p33738_Hochbaum |
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todo:paper_00219258_v278_n36_p33738_Hochbaum2023-10-03T14:23:03Z Activation of JNK by Epac Is Independent of Its Activity as a Rap Guanine Nucleotide Exchanger Hochbaum, D. Tanos, T. Ribeiro-Neto, F. Altschulerll, D. Coso, O.A. Catalysis Cells Proteins Mutants Biochemistry guanine nucleotide exchange factor Janus kinase Rap protein complementary DNA DNA glutathione transferase guanine nucleotide exchange factor mitogen activated protein kinase mitogen activated protein kinase 1 mitogen activated protein kinase 3 mitogen activated protein kinase kinase mitogen activated protein kinase kinase 4 mitogen activated protein kinase p38 RAPGEF3 protein, human stress activated protein kinase Vpr protein animal cell article catalysis cell proliferation deletion mutant enzyme activation enzyme activity enzyme specificity genetic analysis nonhuman priority journal protein domain protein family protein stability second messenger signal transduction cell line dominant gene enzyme activation gene deletion genetic transfection human metabolism mutation plasmid protein binding protein motif protein tertiary structure time Western blotting Animalia Janus Amino Acid Motifs Blotting, Western Cell Line DNA DNA, Complementary Enzyme Activation Gene Deletion Gene Products, vpr Genes, Dominant Glutathione Transferase Guanine Nucleotide Exchange Factors Humans JNK Mitogen-Activated Protein Kinases MAP Kinase Kinase 4 Mitogen-Activated Protein Kinase 1 Mitogen-Activated Protein Kinase 3 Mitogen-Activated Protein Kinase Kinases Mitogen-Activated Protein Kinases Mutation p38 Mitogen-Activated Protein Kinases Plasmids Protein Binding Protein Structure, Tertiary Signal Transduction Time Factors Transfection Guanine nucleotide exchange factors (GEFs) and their associated GTP-binding proteins (G-proteins) are key regulatory elements in the signal transduction machinery that relays information from the extracellular environment into specific intracellular responses. Among them, the MAPK cascades represent ubiquitous downstream effector pathways. We have previously described that, analogous to the Ras-dependent activation of the Erk-1/2 pathway, members of the Rho family of small G-proteins activate the JNK cascade when GTP is loaded by their corresponding GEFs. Searching for novel regulators of JNK activity we have identified Epac (exchange protein activated by cAMP) as a strong activator of JNK-1. Epac is a member of a growing family of GEFs that specifically display exchange activity on the Rap subfamily of Ras small G-proteins. We report here that while Epac activates the JNK severalfold, a constitutively active (G12V) mutant of Raplb does not, suggesting that Rap-GTP is not sufficient to transduce Epac-dependent JNK activation. Moreover, Epac signaling to the JNKs was not blocked by inactivation of endogenous Rap, suggesting that Rap activation is not necessary for this response. Consistent with these observations, domain deletion mutant analysis shows that the catalytic GEF domain is dispensable for Epac-mediated activation of JNK. These studies identified a region overlapping the Ras exchange motif domain as critical for JNK activation. Consistent with this, an isolated Ras exchange motif domain from Epac is sufficient to activate JNK. We conclude that Epac signals to the JNK cascade through a new mechanism that does not involve its canonical catalytic action, i.e. Rap-specific GDP/GTP exchange. This represents not only a novel way to activate the JNKs but also a yet undescribed mechanism of downstream signaling by Epac. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00219258_v278_n36_p33738_Hochbaum |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Catalysis Cells Proteins Mutants Biochemistry guanine nucleotide exchange factor Janus kinase Rap protein complementary DNA DNA glutathione transferase guanine nucleotide exchange factor mitogen activated protein kinase mitogen activated protein kinase 1 mitogen activated protein kinase 3 mitogen activated protein kinase kinase mitogen activated protein kinase kinase 4 mitogen activated protein kinase p38 RAPGEF3 protein, human stress activated protein kinase Vpr protein animal cell article catalysis cell proliferation deletion mutant enzyme activation enzyme activity enzyme specificity genetic analysis nonhuman priority journal protein domain protein family protein stability second messenger signal transduction cell line dominant gene enzyme activation gene deletion genetic transfection human metabolism mutation plasmid protein binding protein motif protein tertiary structure time Western blotting Animalia Janus Amino Acid Motifs Blotting, Western Cell Line DNA DNA, Complementary Enzyme Activation Gene Deletion Gene Products, vpr Genes, Dominant Glutathione Transferase Guanine Nucleotide Exchange Factors Humans JNK Mitogen-Activated Protein Kinases MAP Kinase Kinase 4 Mitogen-Activated Protein Kinase 1 Mitogen-Activated Protein Kinase 3 Mitogen-Activated Protein Kinase Kinases Mitogen-Activated Protein Kinases Mutation p38 Mitogen-Activated Protein Kinases Plasmids Protein Binding Protein Structure, Tertiary Signal Transduction Time Factors Transfection |
| spellingShingle |
Catalysis Cells Proteins Mutants Biochemistry guanine nucleotide exchange factor Janus kinase Rap protein complementary DNA DNA glutathione transferase guanine nucleotide exchange factor mitogen activated protein kinase mitogen activated protein kinase 1 mitogen activated protein kinase 3 mitogen activated protein kinase kinase mitogen activated protein kinase kinase 4 mitogen activated protein kinase p38 RAPGEF3 protein, human stress activated protein kinase Vpr protein animal cell article catalysis cell proliferation deletion mutant enzyme activation enzyme activity enzyme specificity genetic analysis nonhuman priority journal protein domain protein family protein stability second messenger signal transduction cell line dominant gene enzyme activation gene deletion genetic transfection human metabolism mutation plasmid protein binding protein motif protein tertiary structure time Western blotting Animalia Janus Amino Acid Motifs Blotting, Western Cell Line DNA DNA, Complementary Enzyme Activation Gene Deletion Gene Products, vpr Genes, Dominant Glutathione Transferase Guanine Nucleotide Exchange Factors Humans JNK Mitogen-Activated Protein Kinases MAP Kinase Kinase 4 Mitogen-Activated Protein Kinase 1 Mitogen-Activated Protein Kinase 3 Mitogen-Activated Protein Kinase Kinases Mitogen-Activated Protein Kinases Mutation p38 Mitogen-Activated Protein Kinases Plasmids Protein Binding Protein Structure, Tertiary Signal Transduction Time Factors Transfection Hochbaum, D. Tanos, T. Ribeiro-Neto, F. Altschulerll, D. Coso, O.A. Activation of JNK by Epac Is Independent of Its Activity as a Rap Guanine Nucleotide Exchanger |
| topic_facet |
Catalysis Cells Proteins Mutants Biochemistry guanine nucleotide exchange factor Janus kinase Rap protein complementary DNA DNA glutathione transferase guanine nucleotide exchange factor mitogen activated protein kinase mitogen activated protein kinase 1 mitogen activated protein kinase 3 mitogen activated protein kinase kinase mitogen activated protein kinase kinase 4 mitogen activated protein kinase p38 RAPGEF3 protein, human stress activated protein kinase Vpr protein animal cell article catalysis cell proliferation deletion mutant enzyme activation enzyme activity enzyme specificity genetic analysis nonhuman priority journal protein domain protein family protein stability second messenger signal transduction cell line dominant gene enzyme activation gene deletion genetic transfection human metabolism mutation plasmid protein binding protein motif protein tertiary structure time Western blotting Animalia Janus Amino Acid Motifs Blotting, Western Cell Line DNA DNA, Complementary Enzyme Activation Gene Deletion Gene Products, vpr Genes, Dominant Glutathione Transferase Guanine Nucleotide Exchange Factors Humans JNK Mitogen-Activated Protein Kinases MAP Kinase Kinase 4 Mitogen-Activated Protein Kinase 1 Mitogen-Activated Protein Kinase 3 Mitogen-Activated Protein Kinase Kinases Mitogen-Activated Protein Kinases Mutation p38 Mitogen-Activated Protein Kinases Plasmids Protein Binding Protein Structure, Tertiary Signal Transduction Time Factors Transfection |
| description |
Guanine nucleotide exchange factors (GEFs) and their associated GTP-binding proteins (G-proteins) are key regulatory elements in the signal transduction machinery that relays information from the extracellular environment into specific intracellular responses. Among them, the MAPK cascades represent ubiquitous downstream effector pathways. We have previously described that, analogous to the Ras-dependent activation of the Erk-1/2 pathway, members of the Rho family of small G-proteins activate the JNK cascade when GTP is loaded by their corresponding GEFs. Searching for novel regulators of JNK activity we have identified Epac (exchange protein activated by cAMP) as a strong activator of JNK-1. Epac is a member of a growing family of GEFs that specifically display exchange activity on the Rap subfamily of Ras small G-proteins. We report here that while Epac activates the JNK severalfold, a constitutively active (G12V) mutant of Raplb does not, suggesting that Rap-GTP is not sufficient to transduce Epac-dependent JNK activation. Moreover, Epac signaling to the JNKs was not blocked by inactivation of endogenous Rap, suggesting that Rap activation is not necessary for this response. Consistent with these observations, domain deletion mutant analysis shows that the catalytic GEF domain is dispensable for Epac-mediated activation of JNK. These studies identified a region overlapping the Ras exchange motif domain as critical for JNK activation. Consistent with this, an isolated Ras exchange motif domain from Epac is sufficient to activate JNK. We conclude that Epac signals to the JNK cascade through a new mechanism that does not involve its canonical catalytic action, i.e. Rap-specific GDP/GTP exchange. This represents not only a novel way to activate the JNKs but also a yet undescribed mechanism of downstream signaling by Epac. |
| format |
JOUR |
| author |
Hochbaum, D. Tanos, T. Ribeiro-Neto, F. Altschulerll, D. Coso, O.A. |
| author_facet |
Hochbaum, D. Tanos, T. Ribeiro-Neto, F. Altschulerll, D. Coso, O.A. |
| author_sort |
Hochbaum, D. |
| title |
Activation of JNK by Epac Is Independent of Its Activity as a Rap Guanine Nucleotide Exchanger |
| title_short |
Activation of JNK by Epac Is Independent of Its Activity as a Rap Guanine Nucleotide Exchanger |
| title_full |
Activation of JNK by Epac Is Independent of Its Activity as a Rap Guanine Nucleotide Exchanger |
| title_fullStr |
Activation of JNK by Epac Is Independent of Its Activity as a Rap Guanine Nucleotide Exchanger |
| title_full_unstemmed |
Activation of JNK by Epac Is Independent of Its Activity as a Rap Guanine Nucleotide Exchanger |
| title_sort |
activation of jnk by epac is independent of its activity as a rap guanine nucleotide exchanger |
| url |
http://hdl.handle.net/20.500.12110/paper_00219258_v278_n36_p33738_Hochbaum |
| work_keys_str_mv |
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| _version_ |
1807317546522640384 |