Note | In the early 90s, several groups identified in murine brain extracts, a protein of a molecular weight between 100-160 kDa, named Ras-GRF (Ras-Guanine nucleotide Releasing Factor) and Cdc25Mm, based on its ability to induce GDP release in p21ras and on its high homology with the Sacharomyces cerevisiae gene CDC25, whose deficiency it could rescue. |
| |
|  |
| |
| The diagram shows the functional modules present in Ras-GRF1. The flanking amino-acid limits shown correspond to the human protein. Arrows indicate the phosphorylation sites that have been characterized and, in brackets, the kinases responsible. It should be noted that Ras-GRF1 has approximately 83 predicted phosphorylation sites; 63 serines, 19 threonines and 11 tyrosines. The regions essential for inducing GDP/GTP release in Rac and Ras GTPases are underlined. Other interacting proteins and the regions involved in such interactions are shown by broken lines. PM, Plasma Membrane; CaM, Calmodulin. The descriptions of Ras-GRF domains can be found in the text. |
| |
Description | Ras-GRF1 is a protein that contains multiple modular motifs. The Ras-GEF region, includes the Cdc25 domain which exhibits guanine nucleotide exchange factor (GEF) activity towards the Ras family GTPase and a REM (Ras Exchanger-stabilization Motif) domain, responsible for the stabilization of the core of the Cdc25 domain. Separating these domains, there is a region rich in proline, glutamic acid, serine and treonine aminoacids (PEST) that constitutes a hypothetical target for proteolysis. Ras-GRF1 also possesses: two pleckstrin-homology (PH) domains, which have been suggested to interact with polyphosphoinositides and other types of phospholipids and may play some role in Ras-GRF1 interactions with membranes: the α-helical coiled-coil (CC) motif plays a role in protein-protein interactions; a Isoleucine-Glutamin (IQ) domain, which binds Calmodulin and is responsible for the calcium-dependent activation of Ras-GRF1; and a dbl-homology (DH) region, which exhibits GEF activity towards Rho family GTPases, in particular Rac-1. The DH domain also mediates in Ras-GRF dimerization that ensues upon activation. The DH domain and the second PH domain constitute the catalytic module, archetypically present in all Rho-GEFs, which entails nucleotide exchange activity over Rho family GTPases. Ras-GRF1, along with Ras-GRF2 and Sos, are the only known exchange factors that combine Rho and Ras exchanger activity in the same protein. |
Expression | Ras-GRF1 is fundamentally expressed in the central nervous system and, at a reduced level, also in the spinal cord. It is more abundant in hippocampus, some deep nuclei, neocortex, and the granule cell layer of the anterior lobules of the cerebellum. Its expression is low during embryonary development and increased drastically in the first days after birth. Its presence has also been reported in pancreatic beta cells. Alternative splicing variants are expressed in brain, lung, pancreas, as well as several tumour cell lines. |
Localisation | By immunofluorescence, Ras-GRF1 exhibits a predominant cytoplasmic distribution, particularly at the perinuclear area, and mostly excluded from lamelipodia and peripheral structures. However, significant amounts are also associated to the plasma-membrane and in the endoplasmic reticulum, but not the Golgi Apparatus. Such a distribution can be ascertained by biochemical fractionation, which shows Ras-GRF1 in both soluble and particulate fractions, its proportions vary depending on the cell type. Its association with membranes does not increase upon activation. In addition, it is also remarkably present in the synaptic junctions of mature neurons. |
Function | The main function of Ras-GRF1, relays in its ability to activate GTPases in response to signals emanating from G protein-coupled receptors and from calcium fluxes. Ras-GRF1 also plays an important role linking signals from AMPA and NMDA receptors to the MAPK/ERK cascade in mature neurons. Initially, it was believed that Ras-GRF1 was unresponsive to signals generated by tyrosine kinase receptors, but lately, it has been demonstrated that Trk-family receptors can phosphorylate and directly associate to Ras-GRF1. Ras-GRF1 acts as a bifunctional protein with the ability to activate both Ras and Rac-1 GTPases. In vitro, Ras-GRF1 can activate H-Ras, K-Ras and N-Ras GTPases, but in vivo, its specificity is reduced to H-Ras, probably as a consequence of microlocalization processes taking place. Ras-GRF1 can also activate the R-Ras subfamily GTPases, namely: , TC21 and M-Ras. On the other hand, Ras-GRF1 acts as a Rac-GEF when activated in a Gβγ-dependent fashion. Another Rho-family GTPase, Cdc42, exhibits a functional relationship with Ras-GRF1 activity, by being capable of negatively regulating Ras-GRF1 Ras-GEF functions. The mechanisms whereby such a regulation is achieved are yet unknown. Ras-GRF1 knock-out mice are viable and show no major developmental alterations. They do show some mental restrains: they are severely impaired in amygdala-dependent long-term synaptic plasticity and show higher basal synaptic activity at both amygdala and hippocampal synapses, showing faults in the process of memory consolidation. They also show a higher neuronal excitability, are more susceptible to convulsionant drugs and do not exhibit tolerance to chronic exposure to cannabinoids. It has also shown a protective role in the stroke-associated neuronal degeneration. With respect to non-CNS effects, Ras-GRF1 knock-out mice exhibit body weight loss, hypoinsulinemia and glucose intolerance, owing to a reduction of pancreatic beta-cells. As a regulator of the activation of Ras GTPases, Ras-GRF1 could, conceptually, participate in all the processes regulated by those, including proliferation, survival and transformation. However, its restricted expression to the brain and localization in the synaptic junctions, suggest a more specific role. By regulating the activation state of the Rac GTPases, Ras-GRF1 could participate in processes that require cytoskeletal reorganization. Thus, by coordinating the activation of Rac and H-Ras, it can control neuronal morphology and neurite outgrowth in PC12 cells, in response to NGF. Experiments in Knock-out mice also demonstrate that Ras-GRF1 controls synaptic plasticity by regulating a Rac- and p38-dependent long-term depression. Through its association with the p38 scaffolf protein IB2/JIP2, Ras-GRF1 leads to a Rac-dependant activation of the p38 cascade. Moreover, it has been demonstrated that the microtubule-destabilizing factor SCLIP can interact with Ras-GRF1, reducing its ability to activate the Rac/p38 cascade while not affecting the Ras/ERK pathway. The splice variant p75-Ras-GRF1 plays a role in the c-jun-dependent non-adherent growth in Rat1A cells. Recently, it has been shown that, in human melanoma cells, the protein Filamin-A regulates the ubiquination and destabilization of Ras-GRF1 that correlated with a decrease in the expression of MMP-9, a matrix metalloproteinase associated to different biological processes such as growth, invasion and angiogenesis. |
Homology | Ras-GRF1 has a highly homologous protein: Ras-GRF2 (86% homology), which, unlike Ras-GRF1, is more ubiquitously expressed. This protein is similar in its structure to Ras-GRF1, thus also functioning as signal transducer protein. It has been also described in pancreatic beta cells, a protein of 178 aminoacids whose N terminus is identical to that of GRF1 and whose C terminus is unrelated to known proteins (GRF β). |
Ras-specific exchange factor GRF: oligomerization through its Dbl homology domain and calcium-dependent activation of Raf. |
Anborgh PH, Qian X, Papageorge AG, Vass WC, DeClue JE, Lowy DR. |
Mol Cell Biol. 1999 Jul;19(7):4611-22. |
PMID 10373510 |
|
Activation of H-Ras in the endoplasmic reticulum by the RasGRF family guanine nucleotide exchange factors. |
Arozarena I, Matallanas D, Berciano MT, Sanz-Moreno V, Calvo F, Muñoz MT, Egea G, Lafarga M, Crespo P. |
Mol Cell Biol. 2004 Feb;24(4):1516-30. |
PMID 14749369 |
|
SCLIP, a microtubule-destabilizing factor, interacts with RasGRF1 and inhibits its ability to promote Rac activation and neurite outgrowth. |
Baldassa S, Gnesutta N, Fascio U, Sturani E, Zippel R. |
J Biol Chem. 2007 Jan 26;282(4):2333-45. |
PMID 17135267 |
|
Sites of phosphorylation by protein kinase A in CDC25Mm/GRF1, a guanine nucleotide exchange factor for Ras. |
Baouz S, Jacquet E, Accorsi K, Hountondji C, Balestrini M, Zippel R, Sturani E, Parmeggiani A. |
J Biol Chem. 2001 Jan 19;276(3):1742-9. |
PMID 11018028 |
|
A role for the Ras signalling pathway in synaptic transmission and long-term memory. |
Brambilla R, Gnesutta N, Minichiello L, White G, Roylance AJ, Herron CE, Ramsey M, Wolfer DP, Cestari V, Rossi-Arnaud C, Grant SG, Chapman PF, Lipp HP, Sturani E, Klein R. |
Nature. 1997 Nov 20;390(6657):281-6. |
PMID 9384379 |
|
The N-terminal pleckstrin, coiled-coil, and IQ domains of the exchange factor Ras-GRF act cooperatively to facilitate activation by calcium. |
Buchsbaum R, Telliez JB, Goonesekera S, Feig LA. |
Mol Cell Biol. 1996 Sep;16(9):4888-96. |
PMID 8756648 |
|
Regulation of p70 S6 kinase by complex formation between the Rac guanine nucleotide exchange factor (Rac-GEF) Tiam1 and the scaffold spinophilin. |
Buchsbaum RJ, Connolly BA, Feig LA. |
J Biol Chem. 2003 May 23;278(21):18833-41. |
PMID 12531897 |
|
Regulated and constitutive activity by CDC25Mm (GRF), a Ras-specific exchange factor. |
Cen H, Papageorge AG, Vass WC, Zhang KE, Lowy DR. |
Mol Cell Biol. 1993 Dec;13(12):7718-24. |
PMID 8246988 |
|
Laser microdissection and microarray analysis of the hippocampus of Ras-GRF1 knockout mice reveals gene expression changes affecting signal transduction pathways related to memory and learning. |
Fernández-Medarde A, Porteros A, de las Rivas J, Núñez A, Fuster JJ, Santos E. |
Neuroscience. 2007 Apr 25;146(1):272-85. |
PMID 17321057 |
|
To fear or not to fear: what was the question? A potential role for Ras-GRF in memory. |
Finkbeiner S, Dalva MB. |
Bioessays. 1998 Sep;20(9):691-5. (Review) |
PMID 9819557 |
|
Ras-GRF1 signaling is required for normal beta-cell development and glucose homeostasis. |
Font de Mora J, Esteban LM, Burks DJ, Núñez A, Garcés C, Garcèa-Barrado MJ, Iglesias-Osma MC, Moratinos J, Ward JM, Santos E. |
EMBO J. 2003 Jun 16;22(12):3039-49. |
PMID 12805218 |
|
The guanine nucleotide exchange factor RasGRF1 directly binds microtubules via DHPH2-mediated interaction. |
Forlani G, Baldassa S, Lavagni P, Sturani E, Zippel R. |
FEBS J. 2006 May;273(10):2127-38. |
PMID 16649990 |
|
Hippocampus-dependent learning and memory is impaired in mice lacking the Ras-guanine-nucleotide releasing factor 1 (Ras-GRF1). |
Giese KP, Friedman E, Telliez JB, Fedorov NB, Wines M, Feig LA, Silva AJ. |
Neuropharmacology. 2001 Nov;41(6):791-800. |
PMID 11640934 |
|
Cloning and characterization of mouse UBPy, a deubiquitinating enzyme that interacts with the ras guanine nucleotide exchange factor CDC25(Mm)/Ras-GRF1. |
Gnesutta N, Ceriani M, Innocenti M, Mauri I, Zippel R, Sturani E, Borgonovo B, Berruti G, Martegani E. |
J Biol Chem. 2001 Oct 19;276(42):39448-54. |
PMID 11500497 |
|
Expression of alternative forms of Ras exchange factors GRF and SOS1 in different human tissues and cell lines. |
Guerrero C, Rojas JM, Chedid M, Esteban LM, Zimonjic DB, Popescu NC, Font de Mora J, Santos E. |
Oncogene. 1996 Mar 7;12(5):1097-107. |
PMID 8649802 |
|
Ras-GRF activates Ha-Ras, but not N-Ras or K-Ras 4B, protein in vivo. |
Jones MK, Jackson JH. |
J Biol Chem. 1998 Jan 16;273(3):1782-7. |
PMID 9430727 |
|
Neuronal nuclear organization is controlled by cyclin-dependent kinase 5 phosphorylation of Ras Guanine nucleotide releasing factor-1. |
Kesavapany S, Pareek TK, Zheng YL, Amin N, Gutkind JS, Ma W, Kulkarni AB, Grant P, Pant HC. |
Neurosignals. 2006-2007;15(4):157-73. |
PMID 16921254 |
|
Induction of rac-guanine nucleotide exchange activity of Ras-GRF1/CDC25(Mm) following phosphorylation by the nonreceptor tyrosine kinase Src. |
Kiyono M, Kaziro Y, Satoh T. |
J Biol Chem. 2000 Feb 25;275(8):5441-6. |
PMID 10681520 |
|
G protein beta gamma subunit-dependent Rac-guanine nucleotide exchange activity of Ras-GRF1/CDC25(Mm). |
Kiyono M, Satoh T, Kaziro Y. |
Proc Natl Acad Sci U S A. 1999 Apr 27;96(9):4826-31. |
PMID 10220378 |
|
p75-Ras-GRF1 is a c-Jun/AP-1 target protein: its up regulation results in increased Ras activity and is necessary for c-Jun-induced nonadherent growth of Rat1a cells. |
Leaner VD, Donninger H, Ellis CA, Clark GJ, Birrer MJ. |
Mol Cell Biol. 2005 Apr;25(8):3324-37. |
PMID 15798216 |
|
Distinct roles for Ras-guanine nucleotide-releasing factor 1 (Ras-GRF1) and Ras-GRF2 in the induction of long-term potentiation and long-term depression. |
Li S, Tian X, Hartley DM, Feig LA. |
J Neurosci. 2006 Feb 8;26(6):1721-9. |
PMID 16467520 |
|
Cloning by functional complementation of a mouse cDNA encoding a homologue of CDC25, a Saccharomyces cerevisiae RAS activator. |
Martegani E, Vanoni M, Zippel R, Coccetti P, Brambilla R, Ferrari C, Sturani E, Alberghina L. |
EMBO J. 1992 Jun;11(6):2151-7. |
PMID 1376246 |
|
Phosphorylation of serine 916 of Ras-GRF1 contributes to the activation of exchange factor activity by muscarinic receptors. |
Mattingly RR. |
J Biol Chem. 1999 Dec 24;274(52):37379-84. |
PMID 10601308 |
|
Signal transduction elements of TC21, an oncogenic member of the R-Ras subfamily of GTP-binding proteins. |
Movilla N, Crespo P, Bustelo XR. |
Oncogene. 1999 Oct 21;18(43):5860-9. |
PMID 10557073 |
|
Sensitivity of wild type and mutant ras alleles to Ras specific exchange factors: Identification of factor specific requirements. |
Nielsen KH, Gredsted L, Broach JR, Willumsen BM. |
Oncogene. 2001 Apr 19;20(17):2091-100. |
PMID 11360193 |
|
Endogenous expression and protein kinase A-dependent phosphorylation of the guanine nucleotide exchange factor Ras-GRF1 in human embryonic kidney 293 cells. |
Norum JH, Méthi T, Mattingly RR, Levy FO. |
FEBS J. 2005 May;272(9):2304-16. |
PMID 15853814 |
|
Regulatory proteins of R-Ras, TC21/R-Ras2, and M-Ras/R-Ras3. |
Ohba Y, Mochizuki N, Yamashita S, Chan AM, Schrader JW, Hattori S, Nagashima K, Matsuda M. |
J Biol Chem. 2000 Jun 30;275(26):20020-6. |
PMID 10777492 |
|
A growing family of guanine nucleotide exchange factors is responsible for activation of Ras-family GTPases. |
Quilliam LA, Rebhun JF, Castro AF. |
Prog Nucleic Acid Res Mol Biol. 2002;71:391-444. (Review) |
PMID 12102558 |
|
Neurotrophin-dependent tyrosine phosphorylation of Ras guanine-releasing factor 1 and associated neurite outgrowth is dependent on the HIKE domain of TrkA. |
Robinson KN, Manto K, Buchsbaum RJ, MacDonald JI, Meakin SO. |
J Biol Chem. 2005 Jan 7;280(1):225-35. |
PMID 15513915 |
|
Modulation of extracellular signal-regulated kinases cascade by chronic delta 9-tetrahydrocannabinol treatment. |
Rubino T, Forlani G, Viganò D, Zippel R, Parolaro D. |
Mol Cell Neurosci. 2004 Mar;25(3):355-62. |
PMID 15033164 |
|
Molecular cloning of cDNAs encoding a guanine-nucleotide-releasing factor for Ras p21. |
Shou C, Farnsworth CL, Neel BG, Feig LA. |
Nature. 1992 Jul 23;358(6384):351-4. |
PMID 1379346 |
|
Differential response of the Ras exchange factor, Ras-GRF to tyrosine kinase and G protein mediated signals. |
Shou C, Wurmser A, Suen KL, Barbacid M, Feig LA, Ling K. |
Oncogene. 1995 May 18;10(10):1887-93. |
PMID 7761090 |
|
The Ras Guanine nucleotide Exchange Factor CDC25Mm is present at the synaptic junction. |
Sturani E, Abbondio A, Branduardi P, Ferrari C, Zippel R, Martegani E, Vanoni M, Denis-Donini S. |
Exp Cell Res. 1997 Aug 25;235(1):117-23. |
PMID 9281359 |
|
Age-dependent participation of Ras-GRF proteins in coupling calcium-permeable AMPA glutamate receptors to Ras/Erk signaling in cortical neurons. |
Tian X, Feig LA. |
J Biol Chem. 2006 Mar 17;281(11):7578-82. |
PMID 16407208 |
|
Developmentally regulated role for Ras-GRFs in coupling NMDA glutamate receptors to Ras, Erk and CREB. |
Tian X, Gotoh T, Tsuji K, Lo EH, Huang S, Feig LA. |
EMBO J. 2004 Apr 7;23(7):1567-75. |
PMID 15029245 |
|
Involvement of CDC25Mm/Ras-GRF1-dependent signaling in the control of neuronal excitability. |
Tonini R, Franceschetti S, Parolaro D, Sala M, Mancinelli E, Tininini S, Brusetti R, Sancini G, Brambilla R, Martegani E, Sturani E, Zippel R. |
Mol Cell Neurosci. 2001 Dec;18(6):691-701. |
PMID 11749043 |
|
Identification of a mammalian gene structurally and functionally related to the CDC25 gene of Saccharomyces cerevisiae. |
Wei W, Mosteller RD, Sanyal P, Gonzales E, McKinney D, Dasgupta C, Li P, Liu BX, Broek D. |
Proc Natl Acad Sci U S A. 1992 Aug 1;89(15):7100-4. |
PMID 1379731 |
|
Localization of the cellular expression pattern of cdc25NEF and ras in the juvenile rat brain. |
Wei W, Schreiber SS, Baudry M, Tocco G, Broek D. |
Brain Res Mol Brain Res. 1993 Sep;19(4):339-44. |
PMID 8231737 |
|
A cytosolic protein catalyzes the release of GDP from p21ras. |
Wolfman A, Macara IG. |
Science. 1990 Apr 6;248(4951):67-9. |
PMID 2181667 |
|
Regulation of DNA methylation of Rasgrf1. |
Yoon BJ, Herman H, Sikora A, Smith LT, Plass C, Soloway PD. |
Nat Genet. 2002 Jan;30(1):92-6. |
PMID 11753386 |
|
Filamin A-mediated down-regulation of the exchange factor Ras-GRF1 correlates with decreased matrix metalloproteinase-9 expression in human melanoma cells. |
Zhu TN, He HJ, Kole S, D'Souza T, Agarwal R, Morin PJ, Bernier M. |
J Biol Chem. 2007 May 18;282(20):14816-26. |
PMID 17389601 |
|
Ras-GRF, the activator of Ras, is expressed preferentially in mature neurons of the central nervous system. |
Zippel R, Gnesutta N, Matus-Leibovitch N, Mancinelli E, Saya D, Vogel Z, Sturani E. |
Brain Res Mol Brain Res. 1997 Aug;48(1):140-4. |
PMID 9379834 |
|