scholarly journals Genetic Complementation Screen Identifies a Mitogen-activated Protein Kinase Phosphatase, MKP3, as a Regulator of Dopamine Transporter Trafficking

2008 ◽  
Vol 19 (7) ◽  
pp. 2818-2829 ◽  
Author(s):  
Ole Valente Mortensen ◽  
Mads Breum Larsen ◽  
Balakrishna M. Prasad ◽  
Susan G. Amara
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Dopamine Transporter ◽  
Map Kinases ◽  
Kinase Inhibitors ◽  
Mitogen Activated Protein Kinase ◽  
Genetic Complementation ◽  
Monoamine Transporters ◽  
Map Kinase Phosphatase ◽  
Mitogen Activated Protein

The antidepressant and cocaine sensitive plasma membrane monoamine transporters are the primary mechanism for clearance of their respective neurotransmitters and serve a pivotal role in limiting monoamine neurotransmission. To identify molecules in pathways that regulate dopamine transporter (DAT) internalization, we used a genetic complementation screen in Xenopus oocytes to identify a mitogen-activated protein (MAP) kinase phosphatase, MKP3/Pyst1/DUSP6, as a molecule that inhibits protein kinase C–induced (PKC) internalization of transporters, resulting in enhanced DAT activity. The involvement of MKP3 in DAT internalization was verified using both overexpression and shRNA knockdown strategies in mammalian cell models including a dopaminergic cell line. Although the isolation of MKP3 implies a role for MAP kinases in DAT internalization, MAP kinase inhibitors have no effect on internalization. Moreover, PKC-dependent down-regulation of DAT does not correlate with the phosphorylation state of several well-studied MAP kinases (ERK1/2, p38, and SAPK/JNK). We also show that MKP3 does not regulate PKC-induced ubiquitylation of DAT but acts at a more downstream step to stabilize DAT at the cell surface by blocking dynamin-dependent internalization and delaying the targeting of DAT for degradation. These results indicate that MKP3 can act to enhance DAT function and identifies MKP3 as a phosphatase involved in regulating dynamin-dependent endocytosis.

scholarly journals A Role for Mitogen-activated Protein Kinase in the Spindle Assembly Checkpoint in XTC Cells

1997 ◽  
Vol 137 (2) ◽  
pp. 433-443 ◽  
Author(s):  
Xiao Min Wang ◽  
Ye Zhai ◽  
James E. Ferrell
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Map Kinases ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Mitogen Activated Protein Kinase ◽  
Mitotic Progression ◽  
Map Kinase Phosphatase ◽  
Mitogen Activated Protein ◽  
Map Kinase Kinase

The spindle assembly checkpoint prevents cells whose spindles are defective or chromosomes are misaligned from initiating anaphase and leaving mitosis. Studies of Xenopus egg extracts have implicated the Erk2 mitogen-activated protein kinase (MAP kinase) in this checkpoint. Other studies have suggested that MAP kinases might be important for normal mitotic progression. Here we have investigated whether MAP kinase function is required for mitotic progression or the spindle assembly checkpoint in vivo in Xenopus tadpole cells (XTC). We determined that Erk1 and/or Erk2 are present in the mitotic spindle during prometaphase and metaphase, consistent with the idea that MAP kinase might regulate or monitor the status of the spindle. Next, we microinjected purified recombinant XCL100, a Xenopus MAP kinase phosphatase, into XTC cells in various stages of mitosis to interfere with MAP kinase activation. We found that mitotic progression was unaffected by the phosphatase. However, XCL100 rendered the cells unable to remain arrested in mitosis after treatment with nocodazole. Cells injected with phosphatase at prometaphase or metaphase exited mitosis in the presence of nocodazole—the chromosomes decondensed and the nuclear envelope re-formed—whereas cells injected with buffer or a catalytically inactive XCL100 mutant protein remained arrested in mitosis. Coinjection of constitutively active MAP kinase kinase-1, which opposes XCL100's effects on MAP kinase, antagonized the effects of XCL100. Since the only known targets of MAP kinase kinase-1 are Erk1 and Erk2, these findings argue that MAP kinase function is required for the spindle assembly checkpoint in XTC cells.

Involvement of Ras/MAP Kinase in the Regulation of Ca2+ Channels in Adult Bullfrog Sympathetic Neurons by Nerve Growth Factor

1998 ◽  
Vol 80 (3) ◽  
pp. 1352-1361 ◽  
Author(s):  
Saobo Lei ◽  
William F. Dryden ◽  
Peter A. Smith
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Protein Kinase ◽  
Map Kinase ◽  
Kinase Inhibitors ◽  
Sympathetic Neurons ◽  
Mitogen Activated Protein Kinase ◽  
Nerve Growth ◽  
Channel Current ◽  
Mitogen Activated Protein

Lei, Saobo, William F. Dryden, and Peter A. Smith. Involvement of Ras/MAP kinase in the regulation of Ca2+ channels in adult bullfrog sympathetic neurons by nerve growth factor. J. Neurophysiol. 80: 1352–1361, 1998. The cellular mechanisms that underlie nerve growth factor (NGF) induced increase in Ca2+-channel current in adult bullfrog sympathetic B-neurons were examined by whole cell recording techniques. Cells were maintained at low density in neuron-enriched, defined-medium, serum-free tissue culture for 6 days in the presence or absence of NGF (200 ng/ml). The increase in Ba2+ current ( I Ba) density induced by NGF was attenuated by the RNA synthesis inhibitor cordycepin (20 μM), by the DNA transcription inhibitor actinomycin D (0.01 μg/ml), by inhibitors of Ras isoprenylation (perillic acid 0.1–1.0 mM or α-hydroxyfarnesylphosphonic acid 10–100 μM), by tyrosine kinase inhibitors genistein (20 μM) or lavendustin A (1 μM), and by PD98059 (10–100 μM), an inhibitor of mitogen-activated protein kinase kinase. Inhibitors of the phosphatidylinositol 3-kinase (PI3K) pathway (wortmannin, 100 nM, or LY29400, 100 μM) were ineffective as were inhibitors of phospholipase Cγ (U73122 or neomycin, both 100 μM). The effect of NGF persisted in Ca2+-free medium that contained 1.8 mM Mg2+ and 2 mM ethylene glycol-bis(β-aminoethyl ether)- N, N, N′, N′-tetraacetic acid. It was mimicked by a Trk antibody that was capable of inducing neurite outgrowth in explant cultures of bullfrog sympathetic ganglion. Antibodies raised against the low-affinity p75 neurotrophin receptor were ineffective in blocking the effect of NGF on I Ba. These results suggest that NGF-induced increase in Ca2+ channel current in adult sympathetic neurons results, at least in part, from new channel synthesis after Trk activation of Ras and mitogen activated protein kinase by a mechanism that is independent of extracellular Ca2+.

scholarly journals An optimized and versatile synthesis to pyridinylimidazole-type p38α mitogen activated protein kinase inhibitors

2015 ◽  
Vol 13 (43) ◽  
pp. 10699-10704 ◽  
Author(s):  
Ahmed El-Gokha ◽  
Stefan A. Laufer ◽  
Pierre Koch
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Kinase Inhibitors ◽  
Protein Kinase Inhibitors ◽  
Mitogen Activated Protein Kinase ◽  
Synthetic Approach ◽  
Mitogen Activated Protein ◽  
P38α Map Kinase

An optimized and diverse synthetic approach for the preparation of potent pyridinylimidazole-based p38α MAP kinase inhibitors is reported.

scholarly journals Mitogen-Activated Protein Kinase Phosphorylation in Kidneys of βs Sickle Cell Mice

2000 ◽  
Vol 11 (6) ◽  
pp. 1026-1032
Author(s):  
MILITZA KIROYCHEVA ◽  
FAYYAZ AHMED ◽  
GILLIAN M. ANTHONY ◽  
CSABA SZABO ◽  
GARRY J. SOUTHAN ◽  
...  
Keyword(s):  
Map Kinase ◽  
Sickle Cell ◽  
Map Kinases ◽  
Mitogen Activated Protein Kinase ◽  
Reaction Products ◽  
Tyrosine Residues ◽  
Extracellular Signal ◽  
Map Kinase Phosphatase ◽  
Mitogen Activated Protein ◽  
Stress Signals

Abstract. Previous studies in βs sickle cell mice demonstrated renal immunostaining for nitrotyrosine, which is putative evidence of peroxynitrite (ONOO-) formation. ONOO- is known to nitrate tyrosine residues of various enzymes, thereby interfering with phosphorylation and inactivating them. The present study examined the state of phosphorylation of mitogen-activated protein (MAP) kinase signal transduction enzymes, i.e., p38, c-Jun NH2-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK). Western blot performed with antibodies directed against specific phosphorylated threonine/tyrosine residues of these enzymes demonstrated reduced phosphorylation of renal p38 and a trend toward reduced phosphorylation of ERK. In contrast, phosphorylation of renal JNK was markedly increased compared with normal mice. The abundance of MAP kinase phosphatase-1 (MKP-1), a key upstream enzyme that modulates phosphorylation of MAP kinases, was not different in βsversus normal mice. To determine whether nitration of tyrosine by ONOO- was responsible for reduced phosphorylation of p38 and ERK, mercaptoethylguanidine (MEG), a compound known to reduce inducible isoform of nitric oxide synthase activity and to scavenge ONOO-, was administered to βs mice for 5 d. MEG was found to restore phosphorylation of p38 and ERK toward normal levels. These observations provide evidence that ONOO- (or closely related reaction products of NO) contributes to dephosphorylation of p38 and ERK, and presumably reduces activity of these enzymes. The increased phosphorylation of JNK, which suggests activation of this signaling pathway by extracellular stress signals, may play a role in apoptosis in the kidneys of these mice. The changes in phosphorylation of MAP kinase pathways found in this study could have important consequences for regulation of nuclear transcription factors, and thus renal function and pathology in sickle cell kidneys.

scholarly journals Selective deficiency in protein kinase C isoenzyme expression and inadequacy in mitogen-activated protein kinase activation in cord blood T cells

2003 ◽  
Vol 370 (2) ◽  
pp. 497-503 ◽  
Author(s):  
Charles S.T. HII ◽  
Maurizio COSTABILE ◽  
George C. MAYNE ◽  
Channing J. DER ◽  
Andrew W. MURRAY ◽  
...  
Keyword(s):  
T Cells ◽  
Protein Kinase ◽  
Cord Blood ◽  
Map Kinase ◽  
Map Kinases ◽  
Mitogen Activated Protein Kinase ◽  
Biochemical Basis ◽  
Kinase Activation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

The biochemical basis for the reduced lymphokine production by neonatal T cells compared with adult T cells remains poorly defined. Previous studies have raised the possibility that neonatal T cells could be deficient in their ability to transmit signals via protein kinase (PK) C. We now report that while PKC-dependent activation of the mitogen-activated protein (MAP) kinases, c-Jun N-terminal protein kinase and the extracellular signal-regulated protein kinase (ERK)1/ERK2, was deficient in cord blood T cells compared with adult blood T cells, marked activation of the MAP kinases in cord blood T cells was achieved via PKC-independent means. Consistent with a deficiency in the signalling capability of PKC, cord blood T cells were selectively deficient in the expression of PKCβI, ∊, θ and ζ. Stimulation of cord blood T cells resulted in a time-dependent increase in PKC expression, with increases detectable by 4h. This was accompanied by an enhancement in MAP kinase activation via PKC-dependent means. These novel data suggest that an inadequacy in PKC-MAP kinase signalling may be responsible, at least in part, for the phenotype of cord blood T cells.

scholarly journals Insulin regulation of mitogen-activated protein kinase kinase (MEK), mitogen-activated protein kinase and casein kinase in the cell nucleus: a possible role in the regulation of gene expression

1997 ◽  
Vol 323 (3) ◽  
pp. 621-627 ◽  
Author(s):  
Sung-Jin KIM ◽  
Ronald C. KAHN
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Map Kinases ◽  
Nuclear Protein ◽  
Insulin Signalling ◽  
Receptor Activation ◽  
Casein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Intact Cells ◽  
Mitogen Activated Protein

After insulin receptor activation, many cytoplasmic enzymes, including mitogen-activated protein (MAP) kinase, MAP kinase kinase (MEK) and casein kinase II (CKII) are activated, but exactly how insulin signalling progresses to the nucleus remains poorly understood. In Chinese hamster ovary cells overexpressing human insulin receptors [CHO(Hirc)], MEK, CKII and the MAP kinases ERK I and ERK II can be detected by immunoblotting in the nucleus, as well as in the cytoplasm, in the unstimulated state. Nuclear localization of MAP kinase is also observed in 3T3-F442A adipocytes, NIH-3T3 cells and Fao hepatoma cells, whereas MEK is found in the nucleus only in Fao and CHO cells. Insulin treatment for 5–30 min induces a translocation of MEK from the cytoplasm to the nucleus, whereas the MAP kinases and CKII are not translocated into the nucleus in response to insulin during this period. However, nuclear MAP kinase and CKII activities increase by 2–3-fold within 1–10 min after stimulation with insulin. By using gel-shift assays, it has been shown that insulin also stimulates nuclear protein binding to an AP-1 site with kinetics similar to MEK translocation and MAP kinase and CKII activation. Treatment of the extracts in vitro with protein phosphatase 2A or treatment of the intact cells with 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole, a cell-permeable inhibitor of CKII, almost completely blocks the insulin-induced DNA-binding activity, whereas incubation of cells with a MEK inhibitor produces only a slight decrease. These results suggest that insulin signalling results in the activation of serine kinases in the nucleus via two pathways: (1) insulin stimulates the nuclear translocation of some kinases, such as MEK, which might directly phosphorylate nuclear protein substrates or activate other nuclear kinases, and (2) insulin activates nuclear kinases without translocation. The latter is true of CKII, which seems to regulate the binding of nuclear proteins to the AP-1 site, possibly by phosphorylation of AP-1 transcription factors.

Mitogen activated protein kinase 6 and MAP kinase phosphatase 1 are involved in the response of Arabidopsis roots to l-glutamate

2018 ◽  
Vol 96 (4-5) ◽  
pp. 339-351 ◽  
Author(s):  
Jesús Salvador López-Bucio ◽  
Javier Raya-González ◽  
Gustavo Ravelo-Ortega ◽  
León Francisco Ruiz-Herrera ◽  
Maricela Ramos-Vega ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Map Kinase Phosphatase ◽  
Mitogen Activated Protein
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