Kinase Suppressor of Ras Inhibits the Activation of Extracellular Ligand-regulated (ERK) Mitogen-activated Protein (MAP) Kinase by Growth Factors, Activated Ras, and Ras Effectors

Joneson, Tom; Fulton, Jennifer A.; Volle, Deanna J.; Chaika, Oleg V.; Bar–Sagi, Dafna; Lewis, Robert E.

doi:10.1074/jbc.273.13.7743

Cited by 78 publications

(80 citation statements)

References 32 publications

(42 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We now demonstrate that, at lower PEA-15 expression levels, there is increased RSK2 activity by all measures and PEA-15 acts as a scaffold. Overexpression of the MEK/ERK scaffold, KSR, similarly impairs MEK activation of ERK (6,(24)(25)(26). KSR does so by combinatorial inhibition, where at high protein concentrations it binds MEK and ERK independently and thus separates them, whereas at low concentrations it brings them together (14,27).…”

Section: Discussionmentioning

confidence: 99%

ERK MAP kinase is targeted to RSK2 by the phosphoprotein PEA-15

Vaidyanathan

Opoku-Ansah

Pastorino

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The ERK pathway responds to extracellular stimuli and oncogenes by modulating cellular processes, including transcription, adhesion, survival, and proliferation. ERK has diverse substrates that carry out these functions. The processes that are modulated are determined in part by the substrates that ERK phosphorylates. We demonstrate that PEA-15 (phosphoprotein enriched in astrocytes, 15 kDa) targets ERK to RSK2 and thereby enhances RSK2 activation. PEA-15 independently bound ERK and RSK2 and increased ERK association with RSK2 in a concentration-dependent manner. PEA-15 increased RSK2 activity and CREB-mediated transcription, and this process was regulated by phosphorylation of PEA-15. Finally, phorbol ester stimulation of PEA-15-null lymphocytes resulted in impaired RSK2 activation that was rescued by exogenous PEA-15 expression. Therefore, PEA-15 functions as a scaffold to enhance ERK activation of RSK2, and this activity is regulated by phosphorylation. Thus, PEA-15 can integrate signal transduction to provide a specific physiological outcome from activation of the multipotent ERK MAP kinase pathway.signal transduction ͉ scaffold ͉ transcription ͉ lymphocytes T he ERK MAPK signaling cascade has been implicated in diverse physiological processes, including differentiation, proliferation, migration, and adhesion (1). This ability to impact several processes is partly because ERK recognizes an array of substrates both cytoplasmic and nuclear to elicit specific responses. However, how such a multipotent pathway achieves specificity of response is an ongoing problem in understanding ERK function. ERK interaction with scaffolding proteins, regulation of the duration of the ERK signal, and restriction of ERK to specialized subcellular compartments have all been suggested to contribute to this specificity (2-4). However, thus far, the mammalian scaffolding proteins for ERK such as KSR are known to act only upstream of ERK to enhance ERK activation without directing ERK to a particular substrate (5, 6). PEA-15 (phosphoprotein enriched in astrocytes, 15 kDa) is a small death effector domain protein that binds ERK and RSK2 and sequesters them in the cytoplasm (7,8). RSK2 is a substrate of ERK and a kinase that can activate transcription, regulate apoptosis, and control cancer cell proliferation (9-11). Therefore, we investigated whether PEA-15 influences ERK activation of RSK2. We show that increasing expression of PEA-15 enhances ERK binding to RSK2, ERK phosphorylation of RSK2, and RSK2 activity. Moreover, genetic deletion of PEA-15 substantially abrogates ERK activation of RSK2 in astrocytes and lymphocytes. RSK2 activation can be rescued by ectopic expression of PEA-15 in these cells. Thus, PEA-15 functions as a scaffold to enhance ERK binding and phosphorylation of RSK2. It does not affect the phosphorylation of other ERK substrates, such as stathmin and Mnk1. This work provides a model to understand how scaffold proteins can integrate signal transduction and provide specificity in MAP kinase signaling.

show abstract

Section: Discussionmentioning

confidence: 99%

ERK MAP kinase is targeted to RSK2 by the phosphoprotein PEA-15

Vaidyanathan

Opoku-Ansah

Pastorino

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…MEK binds to the kinase domain of KSR [121], which functions as a strong dominant-negative mutant [111,121] when severed from the Nterminus, presumably by sequestering MEK. The biochemical analysis of KSR protein interactions turned up a number of familiar faces, including Hsp90, Hsp70, Cdc37, MEK-1 and -2, and 14-3-3 [78].…”

Section: Holding It Together : Scaffolds and Adapters Ksr And Cnk (Comentioning

confidence: 99%

“…MEK kinases other than Raf have been described, for instance mos, some MEKK isoforms and Tpl-2, but MEK-1\2 are considered very specific kinases with ERK-1\2 as sole substrates [2,3]. Although the overexpression of KSR blocks ERK activation by growth factors, Ras, Raf and MEK [121], this does not necessarily exclude a function in another pathway. Alternatively, the conditional interaction with activated Raf and ERK could indicate a role for KSR in controlling the kinetics of ERK activation, maybe by converting an initial transient activation peak into a sustained stimulation.…”

Section: Holding It Together : Scaffolds and Adapters Ksr And Cnk (Comentioning

confidence: 99%

Meaningful relationships: the regulation of the Ras/Raf/MEK/ERK pathway by protein interactions

Kölch

2000

Biochemical Journal

1,040

118

View full text Add to dashboard Cite

The Ras\Raf\MEK (mitogen-activated protein kinase\ERK kinase)\ERK (extracellular-signal-regulated kinase) pathway is at the heart of signalling networks that govern proliferation, differentiation and cell survival. Although the basic regulatory steps have been elucidated, many features of this pathway are only beginning to emerge. This review focuses on the role of protein-protein interactions in the regulation of this pathway, INTRODUCTIONThe mitogen-activated protein kinase (MAPK) pathway is one of the primordial signalling systems that Nature has used in several permutations to accomplish an amazing variety of tasks. It exists in all eukaryotes, and controls such fundamental cellular processes as proliferation, differentiation, survival and apoptosis. The basic arrangement includes a G-protein working upstream of a core module consisting of three kinases : a MAPK kinase kinase (MAPKKK) that phosphorylates and activates a MAPK kinase (MAPKK), which in turn activates MAPK ( Figure 1). This set-up provides not only for signal amplification, but, maybe even more importantly, for additional regulatory interfaces that allow the kinetics, duration and amplitude of the activity to be precisely tuned. At present we can distinguish six MAPK modules, which share structurally related components, but seem to mediate specific biological responses. For recent reviews on MAPK pathways, the reader is referred to references [1][2][3]. Here we will focus on the regulation of the ERK (extracellular-signal-regulated kinase) pathway, which features Ras as G-protein, Raf as MAPKKK, MEK (MAPK\ERK kinase) as MAPKK and ERK as MAPK.Despite enjoying a decade in the limelight of scientific interest and revealing a plethora of new insights into the circuitry of signalling pathways in general, this pathway still holds many secrets. These pertain mainly to the regulation of Raf, and to a deeper understanding of how specific biological responses are encoded by spatial and temporal changes in the activity and subcellular distribution of the pathway components, and how these fluctuations are orchestrated at the molecular level. Work from many laboratories has highlighted protein-protein interactions as powerful means of co-ordinating signalling processes, most strikingly exemplified by the assembly of multi-protein signalling complexes on activated receptors, or of transcriptionfactor complexes on gene promoters. However, it is becoming Abbreviations used : Bcr, Breakpoint cluster region ; BXB, isolated Raf-1 kinase domain ; CNK, connector-enhancer of KSR ; CK2, casein kinase 2 ; CRD, cysteine-rich domain ; DEF, docking site for ERK, FxFP ; DLK, dual leucine-zipper-bearing kinase ; ERK, extracellular-signal-regulated kinase ; Hsp, heat-shock protein ; KIM, kinase interaction motif ; IκB, inhibitor of NF-κB ; JNK, c-Jun N-terminal kinase ; KSR, kinase suppressor of Ras ; MAPK, mitogen-activated protein kinase ; MAPKK, MAPK kinase ; MAPKKK, MAPK kinase kinase ; MEK, MAPK/ERK kinase ; MEKK, MEK kinase ; MP1, MEK partner 1 ; MUK, MAPK upstream kin...

show abstract

“…Generation of Stable Cell Lines-The bicistronic KSR1 construct was generated by subcloning mouse KSR1-FLAG (36) or mutated forms of KSR1 (31,34) into MSCV⅐IRES⅐GFP using EcoRI and SalI/XhoI restriction endonuclease sites. KSR1 retroviruses were generated by cotransfecting MSCV⅐KSR1⅐IRES⅐GFP retroviral expression plasmids with an ecotropic packaging vector into 293T cells (below).…”

Section: Methodsmentioning

confidence: 99%

Phosphorylation Regulates KSR1 Stability, ERK Activation, and Cell Proliferation

Razidlo

Kortum

Haferbier³

et al. 2004

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Kinase suppressor of Ras (KSR) is a molecular scaffold that interacts with the components of the Raf/MEK/ERK kinase cascade and positively regulates ERK signaling. Phosphorylation of KSR1, particularly at Ser 392 , is a critical regulator of KSR1 subcellular localization and ERK activation. We examined the role of phosphorylation of both Ser 392 and Thr 274 in regulating ERK activation and cell proliferation. We hypothesized that KSR1 phosphorylation is involved in generating signaling specificity through the Raf/MEK/ERK kinase cascade in response to stimulation by different growth factors. In fibroblasts, platelet-derived growth factor stimulation induces sustained ERK activation and promotes S-phase entry. Treatment with epidermal growth factor induces transient ERK activation but fails to drive cells into S phase. Mutation of Ser 392 and Thr 274 (KSR1.TVSA) promotes sustained ERK activation and cell cycle progression with either platelet-derived growth factor or epidermal growth factor treatment. KSR1 ؊/؊ mouse embryo fibroblasts expressing KSR1.TVSA proliferate two times faster and grow to a higher density than cells expressing the same level of wild-type KSR1. In addition, KSR1.TVSA is more stable than wild-type KSR1. These data demonstrate that phosphorylation and stability of the molecular scaffold KSR1 are critical regulators of growth factor-specific responses that promote cell proliferation.

show abstract

Kinase Suppressor of Ras Inhibits the Activation of Extracellular Ligand-regulated (ERK) Mitogen-activated Protein (MAP) Kinase by Growth Factors, Activated Ras, and Ras Effectors

Abstract: Val-12 but had no effect on the ability of Ras Val-12 to induce membrane ruffling. These data indicate that KSR is a potent modulator of a signaling pathway essential to normal and oncogenic cell growth and development.

Cited by 78 publications

References 32 publications

ERK MAP kinase is targeted to RSK2 by the phosphoprotein PEA-15

ERK MAP kinase is targeted to RSK2 by the phosphoprotein PEA-15

Meaningful relationships: the regulation of the Ras/Raf/MEK/ERK pathway by protein interactions

Phosphorylation Regulates KSR1 Stability, ERK Activation, and Cell Proliferation

Contact Info

Product

Resources

About