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Jorge R, Zarich N, Oliva JL, Azañedo M, Martínez N, de la Cruz X, Rojas JM. hSos1 contains a new amino-terminal regulatory motif with specific binding affinity for its pleckstrin homology domain. J Biol Chem 2018; 293:11650. [PMID: 30030385 DOI: 10.1074/jbc.w118.004643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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2
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Oliva JL, Zarich N, Martínez N, Jorge R, Castrillo A, Azañedo M, García-Vargas S, Gutiérrez-Eisman S, Juarranz A, Boscá L, Gutkind JS, Rojas JM. The P34G mutation reduces the transforming activity of K-Ras and N-Ras in NIH 3T3 cells but not of H-Ras. J Biol Chem 2018; 293:11651. [PMID: 30030386 PMCID: PMC6065178 DOI: 10.1074/jbc.w118.004644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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3
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Anta B, Pérez-Rodríguez A, Castro J, García-Domínguez CA, Ibiza S, Martínez N, Durá LM, Hernández S, Gragera T, Peña-Jiménez D, Yunta M, Zarich N, Crespo P, Serrador JM, Santos E, Muñoz A, Oliva JL, Rojas-Cabañeros JM. PGA1-induced apoptosis involves specific activation of H-Ras and N-Ras in cellular endomembranes. Cell Death Dis 2016; 7:e2311. [PMID: 27468687 PMCID: PMC4973357 DOI: 10.1038/cddis.2016.219] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 06/20/2016] [Accepted: 06/21/2016] [Indexed: 12/14/2022]
Abstract
The cyclopentenone prostaglandin A1 (PGA1) is an inducer of cell death in cancer cells. However, the mechanism that initiates this cytotoxic response remains elusive. Here we report that PGA1 triggers apoptosis by a process that entails the specific activation of H- and N-Ras isoforms, leading to caspase activation. Cells without H- and N-Ras did not undergo apoptosis upon PGA1 treatment; in these cells, the cellular demise was rescued by overexpression of either H-Ras or N-Ras. Consistently, the mutant H-Ras-C118S, defective for binding PGA1, did not produce cell death. Molecular analysis revealed a key role for the RAF-MEK-ERK signaling pathway in the apoptotic process through the induction of calpain activity and caspase-12 cleavage. We propose that PGA1 evokes a specific physiological cell death program, through H- and N-Ras, but not K-Ras, activation at endomembranes. Our results highlight a novel mechanism that may be of potential interest for tumor treatment.
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Affiliation(s)
- B Anta
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - A Pérez-Rodríguez
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - J Castro
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - C A García-Domínguez
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - S Ibiza
- Fundación Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid 28029, Spain
| | - N Martínez
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - L M Durá
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - S Hernández
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - T Gragera
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - D Peña-Jiménez
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - M Yunta
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - N Zarich
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - P Crespo
- Departamento de Biologia Molecular, Facultad de Medicina, Instituto de Biomedicina y Biotecnología de Cantabria, Consejo Superior de Investigaciones Cientificas (CSIC)-IDICAN, Universidad de Cantabria, Santander 39011, Spain
| | - J M Serrador
- Departamento de Biología Celular e Inmunología, Centro de Biología Molecular Severo Ochoa (CBMSO), CSIC-UAM, Madrid 28049, Spain
| | - E Santos
- Centro de Investigación del Cancer, IBMCC (CSIC-USAL), Universidad de Salamanca, Salamanca 37007, Spain
| | - A Muñoz
- Instituto de Investigaciones Biomédicas 'Alberto Sols', Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Arturo Duperier 4, Madrid 28029, Spain
| | - J L Oliva
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
| | - J M Rojas-Cabañeros
- Unidad de Biología Celular, Unidad Funcional de Investigación de Enfermedades Crónicas (UFIEC), Instituto de Salud Carlos III, Madrid 28220, Spain
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4
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Oliva JL, Rault JL, Appleton B, Lill A. Erratum to: Oxytocin enhances the appropriate use of human social cues by the domestic dog (Canis familiaris) in an object choice task. Anim Cogn 2015; 18:991. [PMID: 25894674 DOI: 10.1007/s10071-015-0870-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Erratum to: Anim Cogn (2015) 18:767–775 DOI 10.1007/s10071-015-0843-7. Unfortunately, in the original publication the word ‘receptor’ under the sub-heading ‘The effect of gender on the efficacy of oxytocin’ has been incorrectly published as ‘peptide’. The correct text should read as below. Oestrogen is known to enhance the production of oxytocin and its receptor (Rissman 2008), and this may explain why the female dogs in this study did not perform as well as human female subjects in other tests of social cognition, as the majority (88 %) had been spayed, thereby reducing the volume of oestrogen their bodies would be producing. The online version of the original article can be found under doi:10.1007/s10071-015-0843-7.
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Affiliation(s)
- J L Oliva
- School of Biological Sciences, Monash University, Melbourne, Australia,
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5
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Oliva JL, Rault JL, Appleton B, Lill A. Oxytocin enhances the appropriate use of human social cues by the domestic dog (Canis familiaris) in an object choice task. Anim Cogn 2015; 18:767-75. [PMID: 25647172 DOI: 10.1007/s10071-015-0843-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 01/08/2015] [Accepted: 01/26/2015] [Indexed: 02/02/2023]
Abstract
It has been postulated that the neuropeptide, oxytocin, is involved in human-dog bonding. This may explain why dogs, compared to wolves, are such good performers on object choice tasks, which test their ability to attend to, and use, human social cues in order to find hidden food treats. The objective of this study was to investigate the effect of intranasal oxytocin administration, which is known to increase social cognition in humans, on domestic dogs' ability to perform such a task. We hypothesised that dogs would perform better on the task after an intranasal treatment of oxytocin. Sixty-two (31 males and 31 females) pet dogs completed the experiment over two different testing sessions, 5-15 days apart. Intranasal oxytocin or a saline control was administered 45 min before each session. All dogs received both treatments in a pseudo-randomised, counterbalanced order. Data were collected as scores out of ten for each of the four blocks of trials in each session. Two blocks of trials were conducted using a momentary distal pointing cue and two using a gazing cue, given by the experimenter. Oxytocin enhanced performance using momentary distal pointing cues, and this enhanced level of performance was maintained over 5-15 days time in the absence of oxytocin. Oxytocin also decreased aversion to gazing cues, in that performance was below chance levels after saline administration but at chance levels after oxytocin administration.
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Affiliation(s)
- J L Oliva
- School of Biological Sciences, Monash University, Melbourne, Australia,
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6
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Sánchez-Molina S, Estarás C, Oliva JL, Akizu N, Asensio-Juan E, Rojas JM, Martínez-Balbás MA. Regulation of CBP and Tip60 coordinates histone acetylation at local and global levels during Ras-induced transformation. Carcinogenesis 2014; 35:2194-202. [DOI: 10.1093/carcin/bgu111] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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7
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Abstract
The Son of Sevenless (Sos) factors were originally discovered 2 decades ago as specialized Ras activators in signaling pathways controlling the process of R7 cell development in the eye of Drosophila melanogaster. The 2 known members of the mammalian Sos family (Sos1 and Sos2) code for ubiquitously expressed, highly homologous (69% overall) proteins involved in coupling signals originated by cell surface receptor tyrosine kinases (RTKs) to downstream, Ras-dependent mitogenic signaling pathways. Mechanistically, the Sos proteins function as enzymatic factors interacting with Ras proteins in response to upstream stimuli to promote guanine nucleotide exchange (GDP/GTP) and subsequent formation of the active Ras-GTP complex. In this review, we summarize current knowledge on structural, regulatory, and functional aspects of the Sos family, focusing on specific aspects of Sos biology such as structure-function relationship, crosstalk with different signaling pathways, and in vivo functional significance as deduced from phenotypic characterization of Sos knockout mice and human genetic syndromes caused by germline hSos1 mutations.
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Affiliation(s)
- José M Rojas
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain
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8
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García-Domínguez CA, Martínez N, Gragera T, Pérez-Rodríguez A, Retana D, León G, Sánchez A, Oliva JL, Pérez-Sala D, Rojas JM. Sprouty2 and Spred1-2 proteins inhibit the activation of the ERK pathway elicited by cyclopentenone prostanoids. PLoS One 2011; 6:e16787. [PMID: 21364986 PMCID: PMC3043057 DOI: 10.1371/journal.pone.0016787] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Accepted: 01/12/2011] [Indexed: 11/19/2022] Open
Abstract
Sprouty and Spred proteins have been widely implicated in the negative regulation of the fibroblast growth factor receptor-extracellular regulated kinase (ERK) pathway. In considering the functional role of these proteins, we explored their effects on ERK activation induced by cyclopentenone prostanoids, which bind to and activate Ras proteins. We therefore found that ectopic overexpression in HeLa cells of human Sprouty2, or human Spred1 or 2, inhibits ERK1/2 and Elk-1 activation triggered by the cyclopentenone prostanoids PGA1 and 15d-PGJ2. Furthermore, we found that in HT cells that do not express Sprouty2 due to hypermethylation of its gene-promoter, PGA1-provoked ERK activation was more intense and sustained compared to other hematopoietic cell lines with unaltered Sprouty2 expression. Cyclopentenone prostanoids did not induce Sprouty2 tyrosine phosphorylation, in agreement with its incapability to activate tyrosine-kinase receptors. However, Sprouty2 Y55F, which acts as a defective mutant upon tyrosine-kinase receptor stimulation, did not inhibit cyclopentenone prostanoids-elicited ERK pathway activation. In addition, Sprouty2 did not affect the Ras-GTP levels promoted by cyclopentenone prostanoids. These results unveil both common and differential features in the activation of Ras-dependent pathways by cyclopentenone prostanoids and growth factors. Moreover, they provide the first evidence that Sprouty and Spred proteins are negative regulators of the ERK/Elk-1 pathway activation induced not only by growth-factors, but also by reactive lipidic mediators.
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Affiliation(s)
- Carlota A. García-Domínguez
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Natalia Martínez
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Teresa Gragera
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Andrea Pérez-Rodríguez
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Diana Retana
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Gonzalo León
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Agustín Sánchez
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - José Luis Oliva
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Dolores Pérez-Sala
- Departamento de Biología Físico-Química, Centro de Investigaciones Biológicas, C.S.I.C., Ramiro de Maeztu 9, Madrid, Spain
| | - José M. Rojas
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
- * E-mail:
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9
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Martínez N, García-Domínguez CA, Domingo B, Oliva JL, Zarich N, Sánchez A, Gutiérrez-Eisman S, Llopis J, Rojas JM. Sprouty2 binds Grb2 at two different proline-rich regions, and the mechanism of ERK inhibition is independent of this interaction. Cell Signal 2007; 19:2277-85. [PMID: 17689925 DOI: 10.1016/j.cellsig.2007.07.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 06/29/2007] [Accepted: 07/02/2007] [Indexed: 11/19/2022]
Abstract
Sprouty2 has been widely implicated in the negative regulation of the fibroblast growth factor receptor-extracellular regulated kinase (ERK) pathway. Sprouty2 directly interacts with the adapter protein Grb2, member of the receptor tyrosine kinase-induced signaling pathways. In considering the functional role of Grb2, we investigated whether the interaction with this protein was responsible for ERK pathway inhibition. We found that the binding between Sprouty2 and Grb2 is constitutive, independent of Sprouty2 tyrosine phosphorylation, although it is increased when fibroblast growth factor receptor is activated. This connection is mediated by the N-terminal SH3 domain of Grb2 and two Sprouty2 proline-rich stretches (residues 59-64 and 303-307). Most importantly, a double Sprouty2 mutant (hSpry2 P59AP304A), which is unable to bind Grb2, developed at a similar inhibition level of fibroblast growth factor receptor-ERK pathway than that which originated from Sprouty2 wt. These results are evidence that the Sprouty2 mechanism of ERK inhibition is independent of Grb2 binding.
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Affiliation(s)
- Natalia Martínez
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, carretera Majadahonda-Pozuelo, Km 2, Majadahonda-28220, Madrid, Spain
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10
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Zarich N, Oliva JL, Martínez N, Jorge R, Ballester A, Gutiérrez-Eisman S, García-Vargas S, Rojas JM. Grb2 is a negative modulator of the intrinsic Ras-GEF activity of hSos1. Mol Biol Cell 2006; 17:3591-7. [PMID: 16760435 PMCID: PMC1525251 DOI: 10.1091/mbc.e05-12-1104] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
hSos1 is a Ras guanine-nucleotide exchange factor. It was suggested that the carboxyl-terminal region of hSos1 down-regulates hSos1 functionality and that the intrinsic guanine-nucleotide exchange activity of this protein may be different before and after stimulation of tyrosine kinase receptors. Using different myristoylated hSos1 full-length and carboxyl-terminal truncated mutants, we show that Grb2 function accounts not only for recruitment of hSos1 to the plasma membrane but also for modulation of hSos1 activity. Our results demonstrate that the first two canonical Grb2 binding sites, inside the carboxyl-terminal region of hSos1, are responsible for this regulation. Following different approaches, such as displacement of Grb2 from the hSos1-Grb2 complex or depletion of Grb2 levels by small interfering RNA, we found that the full-length Grb2 proteins mediate negative regulation of the intrinsic Ras guanine-nucleotide exchange activity of hSos1.
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Affiliation(s)
- Natasha Zarich
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
| | - José Luis Oliva
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
| | - Natalia Martínez
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
| | - Rocío Jorge
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
| | - Alicia Ballester
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
| | - Silvia Gutiérrez-Eisman
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
| | - Susana García-Vargas
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
| | - José M. Rojas
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
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11
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Abstract
Growth factors exert their cellular effects through signal transduction pathways that are initiated by the ligation of growth factors to their cell surface receptors. One of the well-established effectors of growth factor receptors is protein kinase C (PKC), a family of serine-threonine kinases that have been known for years as the main target of the phorbol ester tumor promoters. While there is abundant information regarding downstream PKC effectors and partners, how individual PKC isozymes become activated by growth factors and the regulation of receptor function by PKCs is only partially understood. Moreover, the identification of novel "non-kinase" DAG-binding proteins has added a new level of complexity to the field of DAG signaling.
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Affiliation(s)
- José Luis Oliva
- School of Medicine, University of Pennsylvania, Department of Pharmacology, Philadelphia, PA 19104-6160, USA
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12
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Oliva JL, Zarich N, Martínez N, Jorge R, Castrillo A, Azañedo M, García-Vargas S, Gutiérrez-Eisman S, Juarranz A, Boscá L, Gutkind JS, Rojas JM. The P34G mutation reduces the transforming activity of K-Ras and N-Ras in NIH 3T3 cells but not of H-Ras. J Biol Chem 2004; 279:33480-91. [PMID: 15181015 DOI: 10.1074/jbc.m404058200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Ras proteins (H-, N-, and K-Ras) operate as molecular switches in signal transduction cascades controlling cell proliferation, differentiation, or apoptosis. The interaction of Ras with its effectors is mediated by the effector-binding loop, but different data about Ras location to plasma membrane subdomains and new roles for some docking/scaffold proteins point to signaling specificities of the different Ras proteins. To investigate the molecular mechanisms for these specificities, we compared an effector loop mutation (P34G) of three Ras isoforms (H-, N-, and K-Ras4B) for their biological and biochemical properties. Although this mutation diminished the capacity of Ras proteins to activate the Raf/ERK and the phosphatidylinositol 3-kinase/AKT pathways, the H-Ras V12G34 mutant retained the ability to cause morphological transformation of NIH 3T3 fibroblasts, whereas both the N-Ras V12G34 and the K-Ras4B V12G34 mutants were defective in this biological activity. On the other hand, although both the N-Ras V12G34 and the K-Ras4B V12G34 mutants failed to promote activation of the Ral-GDS/Ral A/PLD and the Ras/Rac pathways, the H-Ras V12G34 mutant retained the ability to activate these signaling pathways. Interestingly, the P34G mutation reduced specifically the N-Ras and K-Ras4B in vitro binding affinity to Ral-GDS, but not in the case of H-Ras. Thus, independently of Ras location to membrane subdomains, there are marked differences among Ras proteins in the sensitivity to an identical mutation (P34G) affecting the highly conserved effector-binding loop.
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Affiliation(s)
- José Luis Oliva
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), 28220 Majadahonda, Madrid, Spain
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13
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Jorge R, Zarich N, Oliva JL, Azañedo M, Martínez N, de la Cruz X, Rojas JM. HSos1 contains a new amino-terminal regulatory motif with specific binding affinity for its pleckstrin homology domain. J Biol Chem 2002; 277:44171-9. [PMID: 12223473 DOI: 10.1074/jbc.m204423200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protein hSos1 is a Ras guanine nucleotide exchange factor. In the present study, we investigated the function of the amino-terminal region of the hSos1 protein, corresponding to the first 600 residues, which includes the Dbl and pleckstrin homology (DH and PH) domains. We demonstrated, using a series of truncated mutants, that this region is absolutely necessary for hSos1 activity. Our results suggest that the first 200 residues (upstream of DH domain), which we called the HF motif on the basis of their homology with histone H2A, may exert negative control over the functional activity of the whole hSos1 protein. In vitro binding analysis showed that the HF motif is able to interact specifically with the PH domain of hSos1. The amino-terminal region of hSos1 may be associated in vivo with an expressed HF motif. These findings document the existence of the HF motif located upstream of the DH domain in the hSos1 protein. This motif may be responsible for the negative control of hSos1, probably by intramolecular binding with the PH domain.
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Affiliation(s)
- Rocío Jorge
- Unidad de Biologia Celular, Centro Nacional de Microbiologia, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
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14
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Abstract
hSos1 isoform II, defined by the presence of a 15 amino acid stretch in its carboxy-terminal region, exhibits higher Grb2 affinity than hSos1 isoform I. In this study, we investigated the cause for this difference and observed that, in addition to the four currently accepted Grb2-binding motifs, a number of additional, putative SH3-minimal binding sites (SH3-MBS) could be identified. The isoform II-specific 15 amino acid stretch contained one of them. Indeed, we demonstrated by site-directed mutagenesis that these SH3-MBS were responsible for the Grb2 interaction, and we found that C-terminal fragments of the two hSos1 isoforms (lacking the four cannonical Grb2-binding motifs, but containing the SH3-minimal binding sites) were able to bind Grb2, with the isoform II fragment showing higher Grb2 affinity than the corresponding isoform I fragment. Furthermore, we provide evidence that C-terminal truncated mutants of either hSos1 isoform, containing only the SH3-minimal binding sites, were able to originate in vivo stable complexes with Grb2. Although, Grb2-binding remains higher in both full-length isoforms, compared to the C-terminal truncated mutants, these mutants were also able to activate Ras, supporting a potential role of this C-terminal region as negative modulator of Sos1 activity. These findings document the existence of a new, functional, SH3-minimal binding site located in the specific stretch of hSos1 isoform II which may be responsible for the increased Grb2 affinity of this isoform in comparison to isoform I, and for the physiological properties differences between both isoforms. Moreover, these SH3-minimal binding sites may be sufficient to attain stable and functional hSosl-Grb2 complexes.
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Affiliation(s)
- N Zarich
- Unidad de Biología Celular, Centro Nacional de Biología Fundamental, Instituto de Salud Carlos III, Madrid, Spain
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15
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Marinero MJ, Penalva V, Oliva JL, Colás B, Prieto JC, López-Ruiz MP. Specific effect of arachidonic acid on 17beta-hydroxysteroid dehydrogenase in rat Leydig cells. FEBS Lett 1998; 422:10-4. [PMID: 9475159 DOI: 10.1016/s0014-5793(97)01584-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
It is well known that arachidonic acid (AA) acts as an intratesticular factor regulating luteinizing hormone-mediated testicular steroidogenesis. The present studies were conducted to determine the effect of AA on steroidogenic enzymes in rat Leydig cells. Exogenously added AA significantly inhibited 22(R)-hydroxy-cholesterol-stimulated testosterone production, which is a clear indication that AA is acting at some point after cholesterol transport to the inner mitochondrial membrane. AA failed to block the conversion of 22(R)-hydroxycholesterol to pregnenolone, indicating that the cytochrome P-450 side-chain cleavage enzyme complex is not the site of inhibition. The present results demonstrate that only 17beta-hydroxysteroid dehydrogenase seems to be involved in the AA action, since nearly 60% inhibition of testosterone production was found when the cells were incubated with androstenedione. Furthermore, no effect of AA was found when androstenediol was used as substrate in the testosterone synthesis, which indicates that 3beta-hydroxysteroid dehydrogenase is not affected by AA. The conversion of AA to its metabolites is not required for its action on 17beta-hydroxysteroid dehydrogenase and the activation of protein kinase C is not involved in the inhibitory effect.
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Affiliation(s)
- M J Marinero
- Unidad de Neuroendocrinologia Molecular, Departamento de Bioquímica y Biología Molecular, Universidad de Alcalá, Alcalá de Henares-Madrid, Spain
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Valencia AM, Oliva JL, Bodega G, Chiloeches A, López-Ruiz P, Prieto JC, Susini C, Colás B. Identification of a protein-tyrosine phosphatase (SHP1) different from that associated with acid phosphatase in rat prostate. FEBS Lett 1997; 406:42-8. [PMID: 9109383 DOI: 10.1016/s0014-5793(97)00235-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Using [32P]poly(Glu,Tyr) as substrate, we have identified, for the first time, in the rat prostatic gland a protein-tyrosine phosphatase activity different from that associated with prostatic acid phosphatase. Concanavalin A-Sepharose 4B was used to separate the two protein-tyrosyl phosphatases activities. The activity retained by the lectin had characteristics of the prostatic acid phosphatase. It was sensitive to inhibition by PNPP and the optimum pH shifted towards physiological values when [32P]poly(Glu,Tyr) was used as substrate. However, the major protein-tyrosine phosphatase activity was not retained by the lectin, and corresponded, at least in part, to SHP1 as probed by the presence of the protein, its mRNA and the loss of PTPase activity after immunodepletion of SHP1. This enzyme is localized within the epithelial cells. Thus, the coexistence of two protein-tyrosine phosphatase activities in rat prostate, one associated with the acid phosphatase and the other related to SHP1, makes it necessary to analyze the importance of both activities in vivo and their possible function regarding prostatic cell growth and its regulation.
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Affiliation(s)
- A M Valencia
- Departamento de Bioquímica y Biología Molecular, Universidad de Alcalá, Madrid, Spain
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