MAP Kinase Modules: The Excursion Model and the Steps that Count

Piala, Alexander T.; Humphreys, John F.; Goldsmith, Elizabeth J.

doi:10.1016/j.bpj.2014.09.024

Cited by 23 publications

(14 citation statements)

References 75 publications

(84 reference statements)

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“…1F). This concept provides another layer of complexity to the thoroughly investigated kinetics of MKK6 dual phosphorylation by ASK1 (35,36), and raises the question of how the central regulatory region plays such an active scaffolding role.…”

Section: Resultsmentioning

confidence: 99%

Structural basis of autoregulatory scaffolding by apoptosis signal-regulating kinase 1

Weijman

Kumar

Jamieson

et al. 2017

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

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Apoptosis signal-regulating kinases (ASK1-3) are apical kinases of the p38 and JNK MAP kinase pathways. They are activated by diverse stress stimuli, including reactive oxygen species, cytokines, and osmotic stress; however, a molecular understanding of how ASK proteins are controlled remains obscure. Here, we report a biochemical analysis of the ASK1 kinase domain in conjunction with its N-terminal thioredoxin-binding domain, along with a central regulatory region that links the two. We show that in solution the central regulatory region mediates a compact arrangement of the kinase and thioredoxin-binding domains and the central regulatory region actively primes MKK6, a key ASK1 substrate, for phosphorylation. The crystal structure of the central regulatory region reveals an unusually compact tetratricopeptide repeat (TPR) region capped by a cryptic pleckstrin homology domain. Biochemical assays show that both a conserved surface on the pleckstrin homology domain and an intact TPR region are required for ASK1 activity. We propose a model in which the central regulatory region promotes ASK1 activity via its pleckstrin homology domain but also facilitates ASK1 autoinhibition by bringing the thioredoxin-binding and kinase domains into close proximity. Such an architecture provides a mechanism for control of ASK-type kinases by diverse activators and inhibitors and demonstrates an unexpected level of autoregulatory scaffolding in mammalian stress-activated MAP kinase signaling.itogen-activated protein (MAP) kinase cascades transmit signals from membrane-associated receptors to intracellular targets to effect changes in cellular behavior. They form a hierarchical system in which activated upstream kinases (MAP3Ks) phosphorylate intermediate MAP kinase kinases (MAP2Ks), which in turn phosphorylate terminal MAP kinases, primarily ERK, p38, and JNK and their isoforms (1). Extensive studies have focused on the activation of RAS-RAF-MEK upstream in the ERK pathway and provided fertile ground for the discovery of new therapeutics (2). In contrast to the ERK pathway, which primarily promotes cellular proliferation, JNK and p38 phosphorylate a range of substrates to promote inflammation and cell death (1, 3). In addition, cross-regulation among the p38, JNK, and ERK pathways is important for the efficacy of various cancer therapies that are in use or in development (4, 5). Molecular details on the more diverse upstream regulation of the p38 and JNK pathways are currently less clear, however.Apoptosis signal-regulating kinases (ASK1-3) are MAP3Ks that trigger cellular responses to redox stress and inflammatory cytokines (6, 7) and play vital roles in innate immunity and viral infection (8-11). When activated, ASK1-3 activate JNK and p38 via phosphorylation of MAP2Ks (MKK3/4/6/7) (12). The key initiator role of ASK1-3 in this pathway means that either too much or too little ASK activity can have pathological effects. For instance, inhibiting ASK1 is beneficial against gastric cancer (13,14), but inactivating mutations in ASK1...

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Section: Resultsmentioning

confidence: 99%

Structural basis of autoregulatory scaffolding by apoptosis signal-regulating kinase 1

Weijman

Kumar

Jamieson

et al. 2017

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

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“…The MAPK cascades are central signaling pathways that regulate essentially all stimulated cellular processes, including proliferation, differentiation, apoptosis, and stress response. The four mammalian MAPK cascades are the extracellular signal regulated kinase 1 and 2 (ERK1/2), the c-Jun N-terminal kinase (JNK), p38, and ERK5 [29,30]. These cascades operate by sequential activation of protein kinases in each layer of the cascade, which eventually leads to phosphorylation of hundreds of substrates that induce and regulate the relevant cellular processes.…”

Section: Introductionmentioning

confidence: 99%

Activation of Signaling Cascades by Weak Extremely Low Frequency Electromagnetic Fields

Kapri-Pardes

Hanoch

Maik-Rachline

et al. 2017

Cell Physiol Biochem

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Background/Aims:Results from recent studies suggest that extremely low frequency magnetic fields (ELF-MF) interfere with intracellular signaling pathways related to proliferative control. The mitogen-activated protein kinases (MAPKs), central signaling components that regulate essentially all stimulated cellular processes, include the extracellular signal-regulated kinases 1/2 (ERK1/2) that are extremely sensitive to extracellular cues. Anti-phospho-ERK antibodies serve as a readout for ERK1/2 activation and are able to detect minute changes in ERK stimulation. The objective of this study was to explore whether activation of ERK1/2 and other signaling cascades can be used as a readout for responses of a variety of cell types, both transformed and non-transformed, to ELF-MF. Methods: We applied ELF-MF at various field strengths and time periods to eight different cell types with an exposure system housed in a tissue culture incubator and followed the phosphorylation of MAPKs and Akt by western blotting. Results: We found that the phosphorylation of ERK1/2 is increased in response to ELF-MF. However, the phosphorylation of ERK1/2 is likely too low to induce ELF-MF-dependent proliferation or oncogenic transformation. The p38 MAPK was very slightly phosphorylated, but JNK or Akt were not. The effect on ERK1/2 was detected for exposures to ELF-MF strengths as low as 0.15 µT and was maximal at ~10 µT. We also show that ERK1/2 phosphorylation is blocked by the flavoprotein inhibitor diphenyleneiodonium, indicating that the response to ELF-MF may be exerted via NADP oxidase similar to the phosphorylation of ERK1/2 in response to microwave radiation. Conclusions: Our results further indicate that cells are responsive to ELF-MF at field strengths much lower than previously suspected and that the effect may be mediated by NADP oxidase. However, the small increase in ERK1/2 phosphorylation is probably insufficient to affect proliferation and oncogenic transformation. Therefore, the results cannot be regarded as proof of the involvement of ELF-MF in cancer in general or childhood leukemia in particular.

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“…The order and processivity of MAP2K and MAPK phosphorylations have been investigated in vitro , mostly from the time‐resolved studies. Phosphorylations of ERK2 and p38 follow a similar mechanism, nonprocessive and primarily through a phosphotyrosine intermediate . Dual phosphorylations of MEK1 and mitogen‐activated protein kinase kinase 6 (MKK6) activation loops occur in a similar order, and the processivity of MKK6 phosphorylation depends on the upstream MAP3K kinase .…”

Section: Introductionmentioning

confidence: 99%

Kinetic and mechanistic studies of p38α MAP kinase phosphorylation by MKK6

Wang

Zhang

et al. 2019

The FEBS Journal

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Bistability (coexistence of two stable steady states in a dynamical system) is a key mechanism of cellular decision‐making and has been observed in many biochemical reaction networks such as mitogen‐activated protein kinase (MAPK) signaling pathways. Theoretical studies have shown that bistability can arise in a single two‐site MAPK phosphorylation and dephosphorylation cycle. However, the bistable behavior mostly relies on the kinetic mechanisms and parameters of this two‐site modification. In exploring the system‐level properties of MAPK regulation, most models to date focus on two limiting reaction regimes, distributive and processive, and are characterized by high levels of parametric uncertainty. Here, we developed a combined kinetic method which applies a continuous spectrophotometric enzyme‐coupled assay incorporated with the viscosity approach, to perform detailed kinetic analyses of p38α MAPK dual phosphorylation by MKK6. Almost all kinetic rate constants for the first and second phosphorylation steps in p38α activation have been quantitatively determined, supporting that the phosphorylation occurs randomly in the first step, albeit preferring the tyrosine residue. The release rates of monophosphorylated p38α from MKK6, either as the product in the first modification or as the substrate in the second step, were comparable to the respective adjacent phosphoryl transfer steps. These results indicated that dual phosphorylation of p38α by MKK6 involves a random, partially processive mechanism. Based on the experimentally determined models and parameters, dynamics of the p38α‐MKK6‐MKP5 system were explored, demonstrating for the first time that bistability can arise with this model at biologically feasible parameter values. Enzymes p38α (http://www.chem.qmul.ac.uk/iubmb/enzyme/EC2/7/11/24.html); MKK6 (http://www.chem.qmul.ac.uk/iubmb/enzyme/EC2/7/12/2.html).

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MAP Kinase Modules: The Excursion Model and the Steps that Count

Cited by 23 publications

References 75 publications

Structural basis of autoregulatory scaffolding by apoptosis signal-regulating kinase 1

Structural basis of autoregulatory scaffolding by apoptosis signal-regulating kinase 1

Activation of Signaling Cascades by Weak Extremely Low Frequency Electromagnetic Fields

Kinetic and mechanistic studies of p38α MAP kinase phosphorylation by MKK6

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