MEK inhibitors: The chemistry and biological activity of U0126, its analogs, and cyclization products

Duncia, John V.; Santella, Joseph B.; Higley, C. Anne; Pitts, William J.; Wityak, John; Frietze, William; Rankin, F.Wayne; Sun, Jung‐Hui; Earl, Richard A.; Tabaka, A. Christine; Teleha, Christopher A.; Blom, Karl F.; Favata, Margaret; Manos, Elizabeth J.; Daulerio, Andrea J.; Stradley, Deborah A.; Horiuchi, Kazuo; Copeland, Robert A.; Scherle, Peggy; Trzaskos, James M.; Magolda, Ronald L.; Trainor, George L.; Wexler, Ruth R.; Hobbs, Frank W.; Olson, R. E.

doi:10.1016/s0960-894x(98)00522-8

Cited by 382 publications

(274 citation statements)

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“…Astrocytes were treated with the ERK-activating kinase (MEK) 1/2 inhibitor U0126 for 45 min before and throughout the addition of Complex. U0126 has been shown to noncompetitively inhibit MEK1 and MEK2 (Duncia et al, 1998) and inhibited ERK1/2 phosphorylation induced by Complex in these experiments (Figure 7A). In parallel experiments, astrocytes were pretreated with the JAK inhibitor AG490.…”

Section: Complex-induced Increase In Cx43 Expression Is Mediated By Tmentioning

confidence: 66%

The Complex of Ciliary Neurotrophic Factor-Ciliary Neurotrophic Factor Receptor α Up-Regulates Connexin43 and Intercellular Coupling in Astrocytes via the Janus Tyrosine Kinase/Signal Transducer and Activator of Transcription Pathway

Ozog

Bernier

Bates

et al. 2004

MBoC

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Cytokines regulate numerous cell processes, including connexin expression and gap junctional coupling. In this study, we examined the effect of ciliary neurotrophic factor (CNTF) on connexin43 (Cx43) expression and intercellular coupling in astrocytes. Murine cortical astrocytes matured in vitro were treated with CNTF (20 ng/ml), soluble ciliary neurotrophic factor receptor ␣ (CNTFR␣) (200 ng/ml), or CNTF-CNTFR␣. Although CNTF and CNTFR␣ alone had no effect on Cx43 expression, the heterodimer CNTF-CNTFR␣ significantly increased both Cx43 mRNA and protein levels. Cx43 immunostaining correlated with increased intercellular coupling as determined by dye transfer analysis. By using the pharmacological inhibitor ␣-cyano-(3,4-dihydroxy)-N-benzylcinnamide (AG490), the increase in Cx43 was found to be dependent on the Janus tyrosine kinase/signal transducer and activator of transcription (JAK/STAT) pathway. Immunocytochemical analysis revealed that CNTF-CNTFR␣ treatment produced nuclear localization of phosphorylated STAT3, whereas CNTF treatment alone did not. Transient transfection of constructs containing various sequences of the Cx43 promoter tagged to a LacZ reporter into ROS 17/2.8 cells confirmed that the promoter region between ؊838 to ؊1693 was deemed necessary for CNTF-CNTFR␣ to induce heightened expression. CNTF-CNTFR␣ did not alter Cx30 mRNA levels, suggesting selectivity of CNTF-CNTFR␣ for connexin signaling. Together in the presence of soluble receptor, CNTF activates the JAK/STAT pathway leading to enhanced Cx43 expression and intercellular coupling. INTRODUCTIONGap junctions are intercellular channels between adjacent cells that permit the passage of various substances Ͻ1.2 kDa in size (Kumar and Gilula, 1996). Such junctions are formed when each cell provides a connexon, which itself is composed of six connexins (Cxs) (Kumar and Gilula, 1996). Cx43, the prominent Cx isoform expressed in the central nervous system (CNS), is highly expressed in astrocytes (Yamamoto et al., 1990;Dermietzel et al., 1991;Giaume et al., 1991), neuronal precursors (Rozental et al., 1998Bittman and LoTurco, 1999), and possibly neurons (Bruzzone and Ressot, 1997;Vaney, 1999;SiuYi et al., 2001;Rouach et al., 2002). Several studies using in vitro and in vivo models have demonstrated that impediment of gap junctional coupling and/or connexin43 expression amplifies cell death and tissue damage in the wake of injuries and diseases (Blanc et al., 1998;Naus et al., 2001;Siushansian et al., 2001;Ozog et al., 2002b;Lin et al., 2003;Nakase et al., 2003). Thus, design of an intervention to up-regulate Cx43 expression and intercellular communication may lead to novel therapies against pathological disturbances.Gap junction expression and activity can be altered on a short-term or long-term basis (reviewed by Giaume and McCarthy, 1996;Rouach and Giaume, 2001). Short-term regulation is the result of posttranslational processing such as phosphorylation or channel blocking. Long-term regulation, however, entails modification of gene transcripti...

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Section: Complex-induced Increase In Cx43 Expression Is Mediated By Tmentioning

confidence: 66%

The Complex of Ciliary Neurotrophic Factor-Ciliary Neurotrophic Factor Receptor α Up-Regulates Connexin43 and Intercellular Coupling in Astrocytes via the Janus Tyrosine Kinase/Signal Transducer and Activator of Transcription Pathway

Ozog

Bernier

Bates

et al. 2004

MBoC

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“…We used U0126, a specific inhibitor of the mitogen-activated kinase kinases MEK1 and MEK2 (Duncia et al, 1998). U0126 (10 M) had no effect on basal proliferation or on muscimol-induced arrest of proliferation (Fig.…”

Section: Intracellular Signaling Pathways Mediating the Effects Of Gamentioning

confidence: 99%

Autocrine/Paracrine Activation of the GABA_AReceptor Inhibits the Proliferation of Neurogenic Polysialylated Neural Cell Adhesion Molecule-Positive (PSA-NCAM⁺) Precursor Cells from Postnatal Striatum

et al. 2003

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GABA and its type A receptor (GABA A R) are present in the immature CNS and may function as growth-regulatory signals during the development of embryonic neural precursor cells. In the present study, on the basis of their isopycnic properties in a buoyant density gradient, we developed an isolation procedure that allowed us to purify proliferative neural precursor cells from early postnatal rat striatum, which expressed the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). These postnatal striatal PSA-NCAM ϩ cells were shown to proliferate in the presence of epidermal growth factor (EGF) and formed spheres that preferentially generated neurons in vitro. We demonstrated that PSA-NCAM ϩ neuronal precursors from postnatal striatum expressed GABA A R subunits in vitro and in situ. GABA elicited chloride currents in PSA-NCAM ϩ cells by activation of functional GABA A R that displayed a typical pharmacological profile. GABA A R activation in PSA-NCAM ϩ cells triggered a complex intracellular signaling combining a tonic inhibition of the mitogen-activated protein kinase cascade and an increase of intracellular calcium concentration by opening of voltagegated calcium channels. We observed that the activation of GABA A R in PSA-NCAM ϩ neuronal precursors from postnatal striatum inhibited cell cycle progression both in neurospheres and in organotypic slices. Furthermore, postnatal PSA-NCAM ϩ striatal cells synthesized and released GABA, thus creating an autocrine/paracrine mechanism that controls their proliferation. We showed that EGF modulated this autocrine/paracrine loop by decreasing GABA production in PSA-NCAM ϩ cells. This demonstration of GABA synthesis and GABA A R function in striatal PSA-NCAM ϩ cells may shed new light on the understanding of key extrinsic cues that regulate the developmental potential of postnatal neuronal precursors in the CNS.

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“…5b). U0126, a structurally independent MEK inhibitor, which potently inhibits both MEK1 and MEK2 (Duncia et al 1998;Favata et al 1998; Fig. 5(a) also failed to reduce survival by GW5074 (Fig.…”

Section: Neuroprotection By Gw5074 Is Mek-erk Independentmentioning

confidence: 99%

The c‐Raf inhibitor GW5074 provides neuroprotection in vitro and in an animal model of neurodegeneration through a MEK‐ERK and Akt‐independent mechanism

Chin

Liu

Morrison

et al. 2004

Journal of Neurochemistry

111

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Cerebellar granule neurons undergo apoptosis when switched from a medium containing high potassium (HK) to one that has low potassium (LK). LK-induced cell death is blocked by GW5074 {5-Iodo-3-[(3,5-dibromo-4-hydroxyphenyl) methylene]-2-indolinone}, a synthetic drug that inhibits c-Raf activity in vitro. GW5074 has no direct effect on the activities of several apoptosis-associated kinases when assayed in vitro. In contrast to its effect in vitro, treatment of neurons with GW5074 causes c-Raf activation (when measured in vitro in the absence of the drug) and stimulates the Raf-MEK-ERK pathway. Treatment of neurons with GW5074 also leads to an increase in the activity of B-Raf, which is not inhibited by GW5074 in vitro at concentrations at which the drug exerts its neuroprotective effect. PD98059 and U0126, two distinct inhibitors of MEK, block the activation of ERK by GW5074 but have no effect on its ability to prevent cell death. Overexpression of a dominant-negative form of Akt does not reduce the efficacy of GW5074, demonstrating an Akt-independent mechanism of action. Neuroprotection is inhibited by SN-50, a specific inhibitor of nuclear factor-kappa B (NF-jB) and by the Ras inhibitor S-trans, trans-farnesylthiosalicylic acid (FTS) implicating NF-jB and Ras in the neuroprotective signaling pathway activated by GW5074. In addition to preventing LK-induced apoptosis, treatment with GW5074 protects against the neurotoxic effects of MPP+ and methylmercury in cerebellar granule neurons, and glutathione depletion-induced oxidative stress in cortical neurons. Furthermore, GW5074 prevents neurodegeneration and improves behavioral outcome in an animal model of Huntington's disease. Given its neuroprotective effect on distinct types of cultured neurons, in response to different neurotoxic stimuli, and in an animal model of neurodegeneration, GW5074 could have therapeutic value against neurodegenerative pathologies in humans.

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MEK inhibitors: The chemistry and biological activity of U0126, its analogs, and cyclization products

Cited by 382 publications

References 10 publications

The Complex of Ciliary Neurotrophic Factor-Ciliary Neurotrophic Factor Receptor α Up-Regulates Connexin43 and Intercellular Coupling in Astrocytes via the Janus Tyrosine Kinase/Signal Transducer and Activator of Transcription Pathway

The Complex of Ciliary Neurotrophic Factor-Ciliary Neurotrophic Factor Receptor α Up-Regulates Connexin43 and Intercellular Coupling in Astrocytes via the Janus Tyrosine Kinase/Signal Transducer and Activator of Transcription Pathway

Autocrine/Paracrine Activation of the GABA_AReceptor Inhibits the Proliferation of Neurogenic Polysialylated Neural Cell Adhesion Molecule-Positive (PSA-NCAM⁺) Precursor Cells from Postnatal Striatum

The c‐Raf inhibitor GW5074 provides neuroprotection in vitro and in an animal model of neurodegeneration through a MEK‐ERK and Akt‐independent mechanism

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MEK inhibitors: The chemistry and biological activity of U0126, its analogs, and cyclization products

Cited by 382 publications

References 10 publications

The Complex of Ciliary Neurotrophic Factor-Ciliary Neurotrophic Factor Receptor α Up-Regulates Connexin43 and Intercellular Coupling in Astrocytes via the Janus Tyrosine Kinase/Signal Transducer and Activator of Transcription Pathway

The Complex of Ciliary Neurotrophic Factor-Ciliary Neurotrophic Factor Receptor α Up-Regulates Connexin43 and Intercellular Coupling in Astrocytes via the Janus Tyrosine Kinase/Signal Transducer and Activator of Transcription Pathway

Autocrine/Paracrine Activation of the GABAAReceptor Inhibits the Proliferation of Neurogenic Polysialylated Neural Cell Adhesion Molecule-Positive (PSA-NCAM+) Precursor Cells from Postnatal Striatum

The c‐Raf inhibitor GW5074 provides neuroprotection in vitro and in an animal model of neurodegeneration through a MEK‐ERK and Akt‐independent mechanism

Contact Info

Product

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Autocrine/Paracrine Activation of the GABA_AReceptor Inhibits the Proliferation of Neurogenic Polysialylated Neural Cell Adhesion Molecule-Positive (PSA-NCAM⁺) Precursor Cells from Postnatal Striatum