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Jitao Guo Jianhua Zhang Xuejie Zhang Zhongmei Zhang Xundong Wei Xuyu Zhou 《The Journal of biological chemistry》2014,289(51):35139-35148
The instability of regulatory T (Treg) cells is involved in the pathogenesis of autoimmune diseases and also highlights safety concerns with regard to clinical Treg cell therapy. Cell-intrinsic molecular events linked to this Treg cell instability in vivo cells, which leads to safety concerns regardingare still obscure. Here we developed a novel luciferase-based reporter system and performed an unbiased screening for kinases that potentially modulate Foxp3 function. We found that the active form of COT/Tpl2 specifically inhibits the DNA binding activity of Foxp3 through a MEK-ERK-dependent pathway. Moreover, Treg cell-specific expression of activated MEK1 led to dysregulation of Treg function and instability of Foxp3 expression in vivo. Our results support the hypothesis that outside inflammatory signals act through the COT/Tpl2-MEK-ERK signaling pathway to destabilize the Treg lineage. 相似文献
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Sharma C Vomastek T Tarcsafalvi A Catling AD Schaeffer HJ Eblen ST Weber MJ 《Journal of cellular biochemistry》2005,94(4):708-719
Specificity in signal transduction can be achieved through scaffolds, anchors, and adapters that assemble generic signal transduction components in specific combinations and locations. MEK Partner-1 (MP1) was identified as a potential "scaffold" protein for the mammalian extracellular signal-regulated kinase (ERK) pathway. To gain insight into the interactions of MP1 with the ERK pathway, we analyzed the ability of MP1 to bind to MEK1, ERK1, and to itself, and the regulation of these interactions. Gel filtration of cell lysates revealed two major MP1 peaks: a broad high molecular weight peak and a 28 kDa complex. An MP1 mutant that lost MEK1 binding no longer enhanced RasV12-stimulated ERK1 activity, and functioned as a dominant negative, consistent with the concept that MP1 function depends on facilitating these oligomerizations. Activation of the ERK pathway by serum or by RasV12 did not detectably affect MP1-MP1 dimerization or MP1-MEK1 interactions, but caused the dissociation of the MP1-ERK1 complex. Surprisingly, pharmacological inhibition of ERK activation did not restore the complex, suggesting that regulation of complex formation occurs independently of ERK phosphorylation. These results support the concept that MP1 functions as a regulator of MAP kinase signaling by binding to MEK1 and regulating its association with a larger signaling complex that may sequentially service multiple molecules of ERK. 相似文献
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Lian Liu Xin Zhang Xiaoning Zhang Di Zhao Li Li Chunhong Ma 《Biochemical and biophysical research communications》2009,382(2):385-389
We discovered a stem cell factor (SCF)-triggered, MEK1-independent, and PI3K-dependent MAPK activation pathway in the Kit-expressing ovarian cancer cell line HEY. When we knocked down MEK1 with RNA interference (RNAi) to study the function of MEK1 on the proliferation and survival of ovarian cancer cells, we found that impaired cell growth still occurred after MEK1 expression had been suppressed, although MAPK activation remained intact. This suggests that there is MEK1-independent activation of MAPK in the SCF-induced ovarian cancer cell growth process, and that MEK1 still plays a crucial role in maintaining the malignant properties of ovarian cancer cells even when it fails to activate MAPK as expected. 相似文献
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Ethier C Labelle Y Poirier GG 《Apoptosis : an international journal on programmed cell death》2007,12(11):2037-2049
Poly(ADP-ribose) polymerase-1 (PARP-1) hyper-activation promotes cell death but the signaling events downstream of PARP-1
activation are not fully identified. To gain further information on the implication of PARP-1 activation and PAR synthesis
on signaling pathways influencing cell death, we exposed HeLa cells to the DNA alkylating agent N-methyl-N′-methyl-nitro-N-nitrosoguanidine (MNNG). We found that massive PAR synthesis leads to down-regulation of ERK1/2 phosphorylation, Bax translocation
to the mitochondria, release of cytochrome c and AIF and subsequently cell death. Inhibition of massive PAR synthesis following MNNG exposure with the PARP inhibitor
PJ34 prevented those events leading to cell survival, whereas inhibition of ERK1/2 phosphorylation by inhibiting MEK counteracted
the cytoprotective effect of PJ34. Together, our results provide evidence that PARP-1-induced cell death by MNNG exposure
in HeLa cells is mediated in part through inhibition of the MEK/ERK signaling pathway and that inhibition of massive PAR synthesis
by PJ34, which promotes sustained activation of ERK1/2, leads to cytoprotection. 相似文献
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We conditionally overexpressed a MEK1 mutant that contains triple mutations in the regulatory and kinase domains, and investigated its effects on the MAP kinase cascade in Swiss 3T3 cells. Expression of the mutant produced a 60% blockade in MAP kinase activity. However, only a modest blockade in DNA synthesis was observed, without any reductions in the phosphorylation of two proteins known to be substrates of MAP kinase. Moreover, the overexpression of MEK1(3A) failed to block endogenous MEK1 activation, although MEK1(3A) formed complexes with both c-Raf and B-Raf as well as p42/p44 MAPK. These results suggest that there may be multiple biochemical inputs into the MEK/MAPK pathway. J. Cell. Biochem. 67:367–377, 1997. © 1997 Wiley-Liss, Inc. 相似文献
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Goettel JA Liang D Hilliard VC Edelblum KL Broadus MR Gould KL Hanks SK Polk DB 《Experimental cell research》2011,(4):452-463
The extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway is a highly conserved signaling pathway that regulates diverse cellular processes including differentiation, proliferation, and survival. Kinase suppressor of Ras-1 (KSR1) binds each of the three ERK cascade components to facilitate pathway activation. Even though KSR1 contains a C-terminal kinase domain, evidence supporting the catalytic function of KSR1 remains controversial. In this study, we produced recombinant wild-type or kinase-inactive (D683A/D700A) KSR1 proteins in Escherichia coli to test the hypothesis that KSR1 is a functional protein kinase. Recombinant wild-type KSR1, but not recombinant kinase-inactive KSR1, underwent autophosphorylation on serine residue(s), phosphorylated myelin basic protein (MBP) as a generic substrate, and phosphorylated recombinant kinase-inactive MAPK/ERK kinase-1 (MEK1). Furthermore, FLAG immunoprecipitates from KSR1−/− colon epithelial cells stably expressing FLAG-tagged wild-type KSR1 (+KSR1), but not vector (+vector) or FLAG-tagged kinase-inactive KSR1 (+D683A/D700A), were able to phosphorylate kinase-inactive MEK1. Since TNF activates the ERK pathway in colon epithelial cells, we tested the biological effects of KSR1 in the survival response downstream of TNF. We found that +vector and +D683A/D700A cells underwent apoptosis when treated with TNF, whereas +KSR1 cells were resistant. However, +KSR1 cells were sensitized to TNF-induced cell loss in the absence of MEK kinase activity. These data provide clear evidence that KSR1 is a functional protein kinase, MEK1 is an in vitro substrate of KSR1, and the catalytic activities of both proteins are required for eliciting cell survival responses downstream of TNF. 相似文献
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By inhibiting the activity of Cdc28/Clb cyclin-dependent protein kinase (CDK) complexes, Sic1 prevents the premature initiation
of S phase in the yeast Saccharomyces cerevisiae. By testing a series of Sic1 truncation mutants, we have mapped the minimal domain necessary for Cdc28/Clb inhibition in
vivo to the C-terminal 70 amino acids of Sic1. Site-directed mutagenesis was used to show that a sequence that matches the
zRxL motif found in mammalian CDK inhibitors is essential for Sic1 function. This motif is not found in the Schizosaccharomyces CDK inhibitor p25rum1, which appears to be a structural and functional homolog of Sic1. Based on the mutational data and sequence comparisons,
we argue that Sic1 and p25rum1 are structurally distinct from the known mammalian CDK inhibitors, but may bind CDK complexes in a manner more closely resembling
CDK substrates like the retinoblastoma and E2F proteins.
Received: 3 February 1999 / Accepted: 23 April 1999 相似文献
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Jinyang Song Shaonan Yang Ruihua Yin Qi Xiao Aijun Ma Xudong Pan 《Journal of cellular biochemistry》2019,120(8):13640-13650
Atherosclerosis (AS) is a chronic inflammatory disease that is characterized by the deposition of lipids in the vascular wall and the formation of foam cells. Macrophages play a critical role in the development of this chronic inflammation. An increasing amount of research shows that microRNAs affect many steps of inflammation. The goal of our study was to investigate the regulatory effect of miR-181a on the NLRP3 inflammasome pathway and explore its possible mechanism. Compared with the control group, the expression of miR-181a was downregulated in the carotid tissue of AS group mice, while the expression of MEK1 and NLRP3-related proteins was upregulated significantly. In vitro, when THP-1 macrophages were stimulated with oxidized low-density lipoprotein (ox-LDL), the expression of miR-181a was decreased, the MEK/ERK/NF-κB inflammatory pathways were activated and the expression of NLRP3 inflammasome-related proteins was upregulated. Exogenous overexpression of miR-181a downregulated the activation of the MEK/ERK/NF-κB pathway and decreased the expression of NLRP3 inflammasome-related proteins (such as NLRP3, caspase-1, interleukin-18 [IL-18], IL-1β, etc). Exogenous miR-181a knockdown showed the opposite results to those of overexpression group. A luciferase reporter assay proved that miR-181a inhibited the expression of MEK1 by binding to its 3′-untranslated region. When we knocked down miR-181a and then treated cells with U0126 before ox-LDL stimulation, we found that U0126 reversed the increased activation of the MEK/ERK/NF-κB pathway and upregulation of NLRP3 inflammasome-related proteins (NLRP3, caspase-1, IL-18, IL-1β) that resulted from miR-181a knockdown. Our study suggests that miR-181a regulates the activation of the NLRP3 inflammatory pathway by altering the activity of the MEK/ERK/NF-κB pathway via targeting of MEK1. 相似文献
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Gyrgy Stl Meharvan Singh Xiaoping Guan C. Dominique Toran‐Allerand 《Developmental neurobiology》2002,50(1):1-12
Confocal laser scanning microscopy was used to identify the cells within organotypic slice cultures of the developing mouse cerebral cortex that respond to estradiol treatment by phosphorylation of ERK1 and ERK2. Estrogen‐responsive cells resembled neurons morphologically and expressed the neuronal marker microtubule‐associated protein 2B. The intracellular distribution of the phospho‐ERK signal was both cytoplasmic and nuclear, but inhibition of protein synthesis abolished the appearance of the nuclear signal. ERK1and ERK2 also coimmunoprecipitated with heat shock protein 90 (Hsp90) in the cerebral cortical explants. Geldanamycin effectively disrupted this association and prevented ERK phosphorylation. Surprisingly, MEK2 but not MEK1 was the principal mediator of estradiol‐induced activation of ERK. Our data demonstrate the requirement for Hsp90 in estrogen‐induced activation of ERK1 and ERK2 by MEK2 in the developing mouse cerebral cortex and also provide insight into alternative mechanisms by which estradiol may influence cytoplasmic and nuclear events in responsive neurons via the MAP kinase cascade. © 2002 Wiley Periodicals, Inc. J Neurobiol 50: 1–12, 2002 相似文献
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Individual phospholipids were assayed in exponentially growing and G1-arrested temperature-sensitive cell division cycle (cdc) mutants of Saccharomyces cerevisiae. It was observed that cdc28 cells which are known to arrest at ‘start’ when shifted to their non-permissive temperature, resulted in a 40% decrease in phosphatidylinositol (PI) level while the phosphatidylserine (PS) content was doubled in these cells. The reduced level of PI was restored in cdc4 and cdc7 mutants which are known to arrest past the ‘start’. The increase in PS level in cdc8 mutant which was probably to compensate the intrinsic charging of membrane environment, was also reduced in cdc4 and cdc7 mutants. Our results demonstrate that PI may play a role in yeast cell division and growth that the abnormalities of cdc28 could also be related to PI decrease. 相似文献
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Rudloff I Bachmann M Pfeilschifter J Mühl H 《The Journal of biological chemistry》2012,287(7):4531-4543
IL-22 is an immunoregulatory cytokine displaying pathological functions in models of autoimmunity like experimental psoriasis. Understanding molecular mechanisms driving IL-22, together with knowledge on the capacity of current immunosuppressive drugs to target this process, may open an avenue to novel therapeutic options. Here, we sought to characterize regulation of human IL22 gene expression with focus on the established model of Jurkat T cells. Moreover, effects of the prototypic immunosuppressant cyclosporin A (CsA) were investigated. We report that IL-22 induction by TPA/A23187 (T/A) or αCD3 is inhibited by CsA or related FK506. Similar data were obtained with peripheral blood mononuclear cells or purified CD3(+) T cells. IL22 promoter analysis (-1074 to +156 bp) revealed a role of an NF-AT (-95/-91 nt) and a CREB (-194/-190 nt) binding site for gene induction. Indeed, binding of CREB and NF-ATc2, but not c-Rel, under the influence of T/A to those elements could be proven by ChIP. Because CsA has the capability to impair IκB kinase (IKK) complex activation, the IKKα/β inhibitor IKKVII was evaluated. IKKVII likewise reduced IL-22 induction in Jurkat cells and peripheral blood mononuclear cells. Interestingly, transfection of Jurkat cells with siRNA directed against IKKα impaired IL22 gene expression. Data presented suggest that NF-AT, CREB, and IKKα contribute to rapid IL22 gene induction. In particular the crucial role of NF-AT detected herein may form the basis of direct action of CsA on IL-22 expression by T cells, which may contribute to therapeutic efficacy of the drug in autoimmunity. 相似文献
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The prophage of bacteriophage P1 is a low copy number plasmid in Escherichia coli and is segregated to daughter cells by an active partition system. The dynamics of the partition process have now been successfully followed by time-lapse photomicroscopy. The process appears to be fundamentally different from that previously inferred from statistical analysis of fixed cells. A focus containing several plasmid copies is captured at the cell center. Immediately before cell division, the copies eject bi-directionally along the long axis of the cell. Cell division traps one or more plasmid copies in each daughter cell. These copies are free to move, associate, and disassociate. Later, they are captured to the new cell center to re-start the cycle. Studies with mutants suggest that the ability to segregate accurately at a very late stage in the cell cycle is dependent on a novel ability of the plasmid to control cell division. Should segregation be delayed, cell division is also delayed until segregation is successfully completed. 相似文献
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Involvement of herpes simplex virus type 1 UL13 protein kinase in induction of SOCS genes,the negative regulators of cytokine signaling 下载免费PDF全文
Yuka Sato Tetsuo Koshizuka Kei Ishibashi Koichi Hashimoto Ken Ishioka Kazufumi Ikuta Shin‐ichi Yokota Nobuhiro Fujii Tatsuo Suzutani 《Microbiology and immunology》2017,61(5):159-167
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Tang Z Mandel LL Yean SL Lin CX Chen T Yanagida M Lin RJ 《Experimental cell research》2003,283(1):101-115
The CLK/STY kinases are a family of dual-specificity protein kinases implicated in the regulation of cellular growth and differentiation. Some of the kinases in the family are shown to phosphorylate serine-arginine-rich splicing factors and to regulate pre-mRNA splicing. However, the actual cellular mechanism that regulates cell growth, differentiation, and development by CLK/STY remains unclear. Here we show that a functionally conserved CLK/STY kinase exists in Schizosaccharomyces pombe, and this orthologue, called Kic1, regulates the cell surface and septum formation as well as a late step in cytokinesis. The Kic1 protein is modified in vivo, likely by phosphorylation, suggesting that it can be involved in a control cascade. In addition, kic1(+) together with dsk1(+), which encodes a related SR-specific protein kinase, constitutes a critical in vivo function for cell growth. The results provide the first in vivo evidence for the functional conservation of the CLK/STY family through evolution from fission yeast to mammals. Furthermore, since cell division and cell-cell interaction are fundamental for the differentiation and development of an organism, the novel cellular role of kic1(+) revealed from this study offers a clue to the understanding of its counterparts in higher eukaryotes. 相似文献
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Upregulated ERK1/2 activity is correlated with androgen receptor (AR) downregulation in certain prostate cancer (PCa) that exhibits androgen deprivation-induced neuroendocrine differentiation, but its functional relevance requires elucidation. We found that sustained ERK1/2 activation using active Raf or MEK1/2 mutants is sufficient to induce AR downregulation at mRNA and protein levels in LNCaP. Downregulation of AR protein, but not mRNA, was blocked by proteasome inhibitors, MG132 and bortezomib, indicating that the pathway regulation is mediated at multiple points. Ectopic expression of a constitutively active AR inhibited Raf/MEK/ERK-mediated regulation of the differentiation markers, neuron-specific enolase and neutral endopeptidase, and the cyclin-dependent kinase inhibitors, p16INK4A and p21CIP1, but not Rb phosphorylation and E2F1 expression, indicating that AR has a specific role in the pathway-mediated differentiation and growth inhibitory signaling. However, despite the sufficient role of Raf/MEK/ERK, its inhibition using U0126 or ERK1/2 knockdown could not block androgen deprivation-induced AR downregulation in an LNCaP neuroendocrine differentiation model, suggesting that additional signaling pathways are involved in the regulation. We additionally report that sustained Raf/MEK/ERK activity can downregulate full length as well as hormone binding domain-deficient AR isoforms in androgen-refractory C4-2 and CWR22Rv1, but not in LAPC4 and MDA-PCa-2b. Our study demonstrates a novel role of the Raf/MEK/ERK pathway in regulating AR expression in certain PCa types and provides an insight into PCa responses to its aberrant activation. 相似文献