Suppression of mutant Kirsten-RAS (KRAS)-driven pancreatic carcinogenesis by dual-specificity MAP kinase phosphatases 5 and 6.

The cytoplasmic phosphatase DUSP6 and its nuclear counterpart DUSP5 are negative regulators of RAS/ERK signalling. Here we use deletion of either Dusp5 or Dusp6 to explore the roles of these phosphatases in a murine model of KRAS-driven pancreatic cancer. By 56-days, loss of either DUSP5 or DUSP6 causes a significant increase in KRAS-driven pancreatic hyperplasia.

DUSP5-mediated inhibition of smooth muscle cell proliferation suppresses pulmonary hypertension and right ventricular hypertrophy.

Pulmonary hypertension (PH) is associated with structural remodeling of pulmonary arteries (PAs) because of excessive proliferation of fibroblasts, endothelial cells, and smooth muscle cells (SMCs). The peptide hormone angiotensin II (ANG II) contributes to pulmonary vascular remodeling, in part, through its ability to trigger extracellular signal-regulated kinase (ERK1/2) activation. Here, we demonstrate that the ERK1/2 phosphatase, dual-specificity phosphatase 5 (DUSP5), functions as a negative regulator of ANG II-mediated SMC proliferation and PH.

The integrin αvβ6 drives pancreatic cancer through diverse mechanisms and represents an effective target for therapy.

Pancreatic ductal adenocarcinoma (PDAC) has a 5-year survival rate of less than 4% and desperately needs novel effective therapeutics. Integrin αvβ6 has been linked with poor prognosis in cancer but its potential as a target in PDAC remains unclear. We report that transcriptional expression analysis revealed that high levels of β6 mRNA correlated strongly with significantly poorer survival (n = 491 cases, p = 3.

Dual-specificity MAP kinase phosphatases in health and disease.

It is well established that a family of dual-specificity MAP kinase phosphatases (MKPs) play key roles in the regulated dephosphorylation and inactivation of MAP kinase isoforms in mammalian cells and tissues. MKPs provide a mechanism of spatiotemporal feedback control of these key signalling pathways, but can also mediate crosstalk between distinct MAP kinase cascades and facilitate interactions between MAP kinase pathways and other key signalling modules. As our knowledge of the regulation, substrate specificity and catalytic mechanisms of MKPs has matured, more recent work using genetic models has revealed key physiological functions for MKPs and also uncovered potentially important roles in regulating the pathophysiological outcome of signalling with relevance to human diseases.

Regulation of atypical MAP kinases ERK3 and ERK4 by the phosphatase DUSP2.

The atypical MAP kinases ERK3 and ERK4 are activated by phosphorylation of a serine residue lying within the activation loop signature sequence S-E-G. However, the regulation of ERK3 and ERK4 phosphorylation and activity is poorly understood. Here we report that the inducible nuclear dual-specificity MAP kinase phosphatase (MKP) DUSP2, a known regulator of the ERK and p38 MAPKs, is unique amongst the MKP family in being able to bind to both ERK3 and ERK4.

Dual-specificity phosphatase 5 controls the localized inhibition, propagation, and transforming potential of ERK signaling.

Deregulated extracellular signal-regulated kinase (ERK) signaling drives cancer growth. Normally, ERK activity is self-limiting by the rapid inactivation of upstream kinases and delayed induction of dual-specificity MAP kinase phosphatases (MKPs/DUSPs). However, interactions between these feedback mechanisms are unclear.

Visualizing and Quantitating the Spatiotemporal Regulation of Ras/ERK Signaling by Dual-Specificity Mitogen-Activated Protein Phosphatases (MKPs).

The spatiotemporal regulation of the Ras/ERK pathway is critical in determining the physiological and pathophysiological outcome of signaling. Dual-specificity mitogen-activated protein kinase (MAPK) phosphatases (DUSPs or MKPs) are key regulators of pathway activity and may also localize ERK to distinct subcellular locations. Here we present methods largely based on the use of high content microscopy to both visualize and quantitate the subcellular distribution of activated (p-ERK) and total ERK in populations of mouse embryonic fibroblasts derived from mice lacking DUSP5, a nuclear ERK-specific MKP.

Heat Shock Factor 1 Is a Substrate for p38 Mitogen-Activated Protein Kinases.

Heat shock factor 1 (HSF1) monitors the structural integrity of the proteome. Phosphorylation at S326 is a hallmark for HSF1 activation, but the identity of the kinase(s) phosphorylating this site has remained elusive. We show here that the dietary agent phenethyl isothiocyanate (PEITC) inhibits heat shock protein 90 (Hsp90), the main negative regulator of HSF1; activates p38 mitogen-activated protein kinase (MAPK); and increases S326 phosphorylation, trimerization, and nuclear translocation of HSF1, and the transcription of a luciferase reporter, as well as the endogenous prototypic HSF1 target Hsp70.

The regulation of oncogenic Ras/ERK signalling by dual-specificity mitogen activated protein kinase phosphatases (MKPs).

Dual-specificity MAP kinase (MAPK) phosphatases (MKPs or DUSPs) are well-established negative regulators of MAPK signalling in mammalian cells and tissues. By virtue of their differential subcellular localisation and ability to specifically recognise, dephosphorylate and inactivate different MAPK isoforms, they are key spatiotemporal regulators of pathway activity. Furthermore, as they are transcriptionally regulated as downstream targets of MAPK signalling they can either act as classical negative feedback regulators or mediate cross talk between distinct MAPK pathways.

New insights into the activation, interaction partners and possible functions of MK5/PRAK.

MAP kinase-activated protein kinase 5 (MK5) was first described as a downstream target of the p38 MAP kinase pathway leading to its alternative acronym of p38-regulated/activated protein kinase (PRAK). However, since the discovery that MK5 is a bona fide interaction partner of the atypical MAP kinases ERK3 and ERK4 and that this interaction leads to both the activation and subcellular relocalisation of MK5, there has been considerable debate as to the relative roles of these MAPK pathways in mediating the activation and biological functions of MK5. Here we discuss recent progress in defining novel upstream components of the ERK3/ERK4 signalling pathway, our increased understanding of the mechanism by which MK5 interacts with and is activated by ERK3 and ERK4, and the discovery of novel interaction partners for MK5.

Selective Expression of the MAPK Phosphatase Dusp9/MKP-4 in Mouse Plasmacytoid Dendritic Cells and Regulation of IFN-β Production.

Plasmacytoid dendritic cells (pDCs) efficiently produce large amounts of type I IFN in response to TLR7 and TLR9 ligands, whereas conventional DCs (cDCs) predominantly secrete high levels of the cytokines IL-10 and IL-12. The molecular basis underlying this distinct phenotype is not well understood. In this study, we identified the MAPK phosphatase Dusp9/MKP-4 by transcriptome analysis as selectively expressed in pDCs, but not cDCs.

Dual-specificity phosphatase 5 regulates nuclear ERK activity and suppresses skin cancer by inhibiting mutant Harvey-Ras (HRasQ61L)-driven SerpinB2 expression.

Ectopic expression of dual-specificity phosphatase 5 (DUSP5), an inducible mitogen-activated protein (MAP) kinase phosphatase, specifically inactivates and anchors extracellular signal-regulated kinase (ERK)1/2 in the nucleus. However, the role of endogenous DUSP5 in regulating the outcome of Ras/ERK kinase signaling under normal and pathological conditions is unknown. Here we report that mice lacking DUSP5 show a greatly increased sensitivity to mutant Harvey-Ras (HRas(Q61L))-driven papilloma formation in the 7,12-Dimethylbenz[a]anthracene/12-O-tetradecanoylphorbol-13-acetate (DMBA/TPA) model of skin carcinogenesis.

Gene trap mice reveal an essential function of dual specificity phosphatase Dusp16/MKP-7 in perinatal survival and regulation of Toll-like receptor (TLR)-induced cytokine production.

MAPK activity is negatively regulated by members of the dual specificity phosphatase (Dusp) family, which differ in expression, substrate specificity, and subcellular localization. Here, we investigated the function of Dusp16/MKP-7 in the innate immune system. The Dusp16 isoforms A1 and B1 were inducibly expressed in macrophages and dendritic cells following Toll-like receptor stimulation.

Dual-specificity MAP kinase phosphatases (MKPs): shaping the outcome of MAP kinase signalling.

Dual-specificity MAP kinase phosphatases (MKPs) provide a complex negative regulatory network that acts to shape the duration, magnitude and spatiotemporal profile of MAP kinase activities in response to both physiological and pathological stimuli. Individual MKPs may exhibit either exquisite specificity towards a single mitogen-activated protein kinase (MAPK) isoform or be able to regulate multiple MAPK pathways in a single cell or tissue. They can act as negative feedback regulators of MAPK activity, but can also provide mechanisms of crosstalk between distinct MAPK pathways and between MAPK signalling and other intracellular signalling modules.

Distinct docking mechanisms mediate interactions between the Msg5 phosphatase and mating or cell integrity mitogen-activated protein kinases (MAPKs) in Saccharomyces cerevisiae.

MAPK phosphatases (MKPs) are negative regulators of signaling pathways with distinct MAPK substrate specificities. For example, the yeast dual specificity phosphatase Msg5 dephosphorylates the Fus3 and Slt2 MAPKs operating in the mating and cell wall integrity pathways, respectively. Like other MAPK-interacting proteins, most MKPs bind MAPKs through specific docking domains.

Phosphorylation of the kinase interaction motif in mitogen-activated protein (MAP) kinase phosphatase-4 mediates cross-talk between protein kinase A and MAP kinase signaling pathways.

MAP kinase phosphatase 4 (DUSP9/MKP-4) plays an essential role during placental development and is one of a subfamily of three closely related cytoplasmic dual-specificity MAPK phosphatases, which includes the ERK-specific enzymes DUSP6/MKP-3 and DUSP7/MKP-X. However, unlike DUSP6/MKP-3, DUSP9/MKP-4 also inactivates the p38α MAP kinase both in vitro and in vivo. Here we demonstrate that inactivation of both ERK1/2 and p38α by DUSP9/MKP-4 is mediated by a conserved arginine-rich kinase interaction motif located within the amino-terminal non-catalytic domain of the protein.

Regulation of Caenorhabditis elegans p53/CEP-1-dependent germ cell apoptosis by Ras/MAPK signaling.

Maintaining genome stability in the germline is thought to be an evolutionarily ancient role of the p53 family. The sole Caenorhabditis elegans p53 family member CEP-1 is required for apoptosis induction in meiotic, late-stage pachytene germ cells in response to DNA damage and meiotic recombination failure. In an unbiased genetic screen for negative regulators of CEP-1, we found that increased activation of the C.

Cross-talk between the p38alpha and JNK MAPK pathways mediated by MAP kinase phosphatase-1 determines cellular sensitivity to UV radiation.

MAPK phosphatase-1 (DUSP1/MKP-1) is a mitogen and stress-inducible dual specificity protein phosphatase, which can inactivate all three major classes of MAPK in mammalian cells. DUSP1/MKP-1 is implicated in cellular protection against a variety of genotoxic insults including hydrogen peroxide, ionizing radiation, and cisplatin, but its role in the interplay between different MAPK pathways in determining cell death and survival is not fully understood. We have used pharmacological and genetic tools to demonstrate that DUSP1/MKP-1 is an essential non-redundant regulator of UV-induced cell death in mouse embryo fibroblasts (MEFs).

Regulation of the inducible nuclear dual-specificity phosphatase DUSP5 by ERK MAPK.

DUSP5 is an inducible, nuclear, dual-specificity phosphatase, which specifically interacts with and inactivates the ERK1/2 MAP kinases in mammalian cells. In addition, expression of DUSP5 causes nuclear translocation of ERK2 indicating that it may act as a nuclear anchor for the inactive kinase. Here we show that induction of DUSP5 mRNA and protein in response to growth factors is dependent on ERK1/2 activation and that the accumulation of DUSP5 protein is regulated by rapid proteasomal degradation.

Docking of PRAK/MK5 to the atypical MAPKs ERK3 and ERK4 defines a novel MAPK interaction motif.

ERK3 and ERK4 are atypical MAPKs in which the canonical TXY motif within the activation loop of the classical MAPKs is replaced by SEG. Both ERK3 and ERK4 bind, translocate, and activate the MAPK-activated protein kinase (MK) 5. The classical MAPKs ERK1/2 and p38 interact with downstream MKs (RSK1-3 and MK2-3, respectively) through conserved clusters of acidic amino acids, which constitute the common docking (CD) domain.

Does MK5 reconcile classical and atypical MAP kinases?

MAP kinase-activated protein kinase 5 (MK5) was originally described as a protein kinase activated downstream of the p38 MAP kinase and is also named p38-regulated/activated protein kinase (PRAK). However, while MK5 is most similar in sequence to the two p38 regulated MAPKAP kinases MK2 and MK3, recent data has shown that in contrast to these enzymes MK5 is not activated in response to either cellular stress or pro-inflammatory cytokines. This lack of response to stimuli which cause robust activation of p38 MAP kinase in vivo is supported by data obtained using transgenic mice lacking MK5.

Dual-specificity MAP kinase phosphatases (MKPs) and cancer.

There are ten mitogen-activated protein kinase (MAPK) phosphatases (MKPs) that act as negative regulators of MAPK activity in mammalian cells and these can be subdivided into three groups. The first comprises DUSP1/MKP-1, DUSP2/PAC1, DUSP4/MKP-2 and DUSP5/hVH-3, which are inducible nuclear phosphatases. With the exception of DUSP5, these MKPs display a rather broad specificity for inactivation of the ERK, p38 and JNK MAP kinases.

Negative-feedback regulation of FGF signalling by DUSP6/MKP-3 is driven by ERK1/2 and mediated by Ets factor binding to a conserved site within the DUSP6/MKP-3 gene promoter.

DUSP6 (dual-specificity phosphatase 6), also known as MKP-3 [MAPK (mitogen-activated protein kinase) phosphatase-3] specifically inactivates ERK1/2 (extracellular-signal-regulated kinase 1/2) in vitro and in vivo. DUSP6/MKP-3 is inducible by FGF (fibroblast growth factor) signalling and acts as a negative regulator of ERK activity in key and discrete signalling centres that direct outgrowth and patterning in early vertebrate embryos. However, the molecular mechanism by which FGFs induce DUSP6/MKP-3 expression and hence help to set ERK1/2 signalling levels is unknown.

DUSP6/MKP-3 inactivates ERK1/2 but fails to bind and inactivate ERK5.

Extracellular signal-regulated kinase-1 and -2 (ERK1/2) are activated by dual threonine and tyrosine phosphorylation of a TEY motif. The highly related kinase ERK5 is also activated by phosphorylation at a TEY motif. Inactivation of ERK1/2 is achieved by distinct members of the dual-specificity protein phosphatase (DUSP) family, which are responsible for the specific, regulated de-phosphorylation of the TEY motif.