scholarly journals Meiotic spindle stability depends on MAPK-interacting and spindle-stabilizing protein (MISS), a new MAPK substrate

2002 ◽  
Vol 157 (4) ◽  
pp. 603-613 ◽  
Author(s):  
Christophe Lefebvre ◽  
M. Emilie Terret ◽  
Alexandre Djiane ◽  
Pascale Rassinier ◽  
Bernard Maro ◽  
...  
Keyword(s):  
Antisense Rna ◽  
Mapk Pathway ◽  
Meiotic Spindle ◽  
Mitogen Activated Protein Kinases ◽  
Mitogen Activated Protein ◽  
Cytostatic Factor ◽  
Morpholino Oligonucleotides ◽  
Spindle Stability ◽  
Two Hybrid ◽  
Segregation Of Chromosomes

Vertebrate oocytes arrest in the second metaphase of meiosis (metaphase II [MII]) by an activity called cytostatic factor (CSF), with aligned chromosomes and stable spindles. Segregation of chromosomes occurs after fertilization. The Mos/…/MAPK (mitogen-activated protein kinases) pathway mediates this MII arrest. Using a two-hybrid screen, we identified a new MAPK partner from a mouse oocyte cDNA library. This protein is unstable during the first meiotic division and accumulates only in MII, where it localizes to the spindle. It is a substrate of the Mos/…/MAPK pathway. The depletion of endogenous RNA coding for this protein by three different means (antisense RNA, double-stranded [ds] RNA, or morpholino oligonucleotides) induces severe spindle defects specific to MII oocytes. Overexpressing the protein from an RNA not targeted by the morpholino rescues spindle destabilization. However, dsRNA has no effect on the first two mitotic divisions. We therefore have discovered a new MAPK substrate involved in maintaining spindle integrity during the CSF arrest of mouse oocytes, called MISS (for MAP kinase–interacting and spindle-stabilizing protein).

scholarly journals Spa2p Interacts with Cell Polarity Proteins and Signaling Components Involved in Yeast Cell Morphogenesis

1998 ◽  
Vol 18 (7) ◽  
pp. 4053-4069 ◽  
Author(s):  
Yi-Jun Sheu ◽  
Beatriz Santos ◽  
Nathalie Fortin ◽  
Christine Costigan ◽  
Michael Snyder
Keyword(s):  
Actin Cytoskeleton ◽  
Hybrid System ◽  
Mapk Pathway ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Velocity Sedimentation ◽  
Mitogen Activated Protein ◽  
Multiple Regions ◽  
Two Hybrid

ABSTRACT The yeast protein Spa2p localizes to growth sites and is important for polarized morphogenesis during budding, mating, and pseudohyphal growth. To better understand the role of Spa2p in polarized growth, we analyzed regions of the protein important for its function and proteins that interact with Spa2p. Spa2p interacts with Pea2p and Bud6p (Aip3p) as determined by the two-hybrid system; all of these proteins exhibit similar localization patterns, and spa2Δ,pea2Δ, and bud6Δ mutants display similar phenotypes, suggesting that these three proteins are involved in the same biological processes. Coimmunoprecipitation experiments demonstrate that Spa2p and Pea2p are tightly associated with each other in vivo. Velocity sedimentation experiments suggest that a significant portion of Spa2p, Pea2p, and Bud6p cosediment, raising the possibility that these proteins form a large, 12S multiprotein complex. Bud6p has been shown previously to interact with actin, suggesting that the 12S complex functions to regulate the actin cytoskeleton. Deletion analysis revealed that multiple regions of Spa2p are involved in its localization to growth sites. One of the regions involved in Spa2p stability and localization interacts with Pea2p; this region contains a conserved domain, SHD-II. Although a portion of Spa2p is sufficient for localization of itself and Pea2p to growth sites, only the full-length protein is capable of complementing spa2 mutant defects, suggesting that other regions are required for Spa2p function. By using the two-hybrid system, Spa2p and Bud6p were also found to interact with components of two mitogen-activated protein kinase (MAPK) pathways important for polarized cell growth. Spa2p interacts with Ste11p (MAPK kinase [MEK] kinase) and Ste7p (MEK) of the mating signaling pathway as well as with the MEKs Mkk1p and Mkk2p of the Slt2p (Mpk1p) MAPK pathway; for both Mkk1p and Ste7p, the Spa2p-interacting region was mapped to the N-terminal putative regulatory domain. Bud6p interacts with Ste11p. The MEK-interacting region of Spa2p corresponds to the highly conserved SHD-I domain, which is shown to be important for mating and MAPK signaling. spa2 mutants exhibit reduced levels of pheromone signaling and an elevated level of Slt2p kinase activity. We thus propose that Spa2p, Pea2p, and Bud6p function together, perhaps as a complex, to promote polarized morphogenesis through regulation of the actin cytoskeleton and signaling pathways.

scholarly journals p90Rsk is not involved in cytostatic factor arrest in mouse oocytes

2005 ◽  
Vol 169 (2) ◽  
pp. 227-231 ◽  
Author(s):  
Julien Dumont ◽  
Muriel Umbhauer ◽  
Pascale Rassinier ◽  
André Hanauer ◽  
Marie-Hélène Verlhac
Keyword(s):  
Mapk Pathway ◽  
Xenopus Laevis Oocytes ◽  
S6 Kinase ◽  
Mouse Oocytes ◽  
Cycle Arrest ◽  
A Cell ◽  
Ribosomal S6 Kinase ◽  
Cytostatic Factor ◽  
Morpholino Oligonucleotides ◽  
Mutant Forms

Vertebrate oocytes arrest in metaphase of the second meiotic division (MII), where they maintain a high cdc2/cyclin B activity and a stable, bipolar spindle because of cytostatic factor (CSF) activity. The Mos–MAPK pathway is essential for establishing CSF. Indeed, oocytes from the mos−/− strain do not arrest in MII and activate without fertilization, as do Xenopus laevis oocytes injected with morpholino oligonucleotides directed against Mos. In Xenopus oocytes, p90Rsk (ribosomal S6 kinase), a MAPK substrate, is the main mediator of CSF activity. We show here that this is not the case in mouse oocytes. The injection of constitutively active mutant forms of Rsk1 and Rsk2 does not induce a cell cycle arrest in two-cell mouse embryos. Moreover, these two mutant forms do not restore MII arrest after their injection into mos−/− oocytes. Eventually, oocytes from the triple Rsk (1, 2, 3) knockout present a normal CSF arrest. We demonstrate that p90Rsk is not involved in the MII arrest of mouse oocytes.

scholarly journals Biological Rationale for Targeting MEK/ERK Pathways in Anti-Cancer Therapy and to Potentiate Tumour Responses to Radiation

2019 ◽  
Vol 20 (10) ◽  
pp. 2530 ◽  
Author(s):  
Francesco Marampon ◽  
Carmela Ciccarelli ◽  
Bianca Maria Zani
Keyword(s):  
Mapk Pathway ◽  
Cell Signalling ◽  
Acquired Resistance ◽  
Mitogen Activated Protein Kinases ◽  
Anti Cancer ◽  
Mitogen Activated Protein ◽  
Splicing Isoforms ◽  
Shed Light ◽  
Pathological Tissues

ERK1 and ERK2 (ERKs), two extracellular regulated kinases (ERK1/2), are evolutionary-conserved and ubiquitous serine-threonine kinases involved in regulating cell signalling in normal and pathological tissues. The expression levels of these kinases are almost always different, with ERK2 being the more prominent. ERK1/2 activation is fundamental for the development and progression of cancer. Since their discovery, much research has been dedicated to their role in mitogen-activated protein kinases (MAPK) pathway signalling and in their activation by mitogens and mutated RAF or RAS in cancer cells. In order to gain a better understanding of the role of ERK1/2 in MAPK pathway signalling, many studies have been aimed at characterizing ERK1/2 splicing isoforms, mutants, substrates and partners. In this review, we highlight the differences between ERK1 and ERK2 without completely discarding the hypothesis that ERK1 and ERK2 exhibit functional redundancy. The main goal of this review is to shed light on the role of ERK1/2 in targeted therapy and radiotherapy and highlight the importance of identifying ERK inhibitors that may overcome acquired resistance. This is a highly relevant therapeutic issue that needs to be addressed to combat tumours that rely on constitutively active RAF and RAS mutants and the MAPK pathway.

PKCε modulates NF-κB and AP-1 via mitogen-activated protein kinases in adult rabbit cardiomyocytes

2000 ◽  
Vol 279 (4) ◽  
pp. H1679-H1689 ◽  
Author(s):  
Richard C. X. Li ◽  
Peipei Ping ◽  
Jun Zhang ◽  
William B. Wead ◽  
Xinan Cao ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Protein Kinases ◽  
Mapk Pathway ◽  
Binding Activity ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Adult Rabbit ◽  
Jnk Pathway ◽  
Mitogen Activated Protein Kinases ◽  
Mitogen Activated Protein

We have previously shown that protein kinase C (PKC)-ε, nuclear factor (NF)-κB, and mitogen-activated protein kinases (MAPKs) are essential signaling elements in ischemic preconditioning. In the present study, we examined whether activation of PKCε affects the activation of NF-κB in cardiac myocytes and whether MAPKs are mediators of this signaling event. Activation of PKCε (+108% above control) in adult rabbit cardiomyocytes to a degree that has been previously shown to protect myocytes against hypoxic injury increased the DNA-binding activity of NF-κB (+164%) and activator protein (AP)-1 (+127%) but not that of Elk-1. Activation of PKCη did not have an effect on these transcription factors. Activation of PKCε also enhanced the phosphorylation activities of the p44/p42 MAPKs and the p54/p46 c-Jun NH2-terminal kinases (JNKs). PKCε-induced activation of NF-κB and AP-1 was completely abolished by inhibition of the p44/p42 MAPK pathway with PD98059 and by inhibition of the p54/p46 JNK pathway with a dominant negative mutant of MAPK kinase-4, indicating that both signaling pathways are necessary. Taken together, these data identify NF-κB and AP-1 as downstream targets of PKCε, thereby establishing a molecular link between activation of PKCε and activation of NF-κB and AP-1 in cardiomyocytes. The results further demonstrate that both the p44/p42 MAPK and the p54/p46 JNK signaling pathways are essential mediators of this event.

scholarly journals Activation of Rac1, RhoA, and mitogen-activated protein kinases is required for Ras transformation.

1995 ◽  
Vol 15 (11) ◽  
pp. 6443-6453 ◽  
Author(s):  
R Khosravi-Far ◽  
P A Solski ◽  
G J Clark ◽  
M S Kinch ◽  
C J Der
Keyword(s):  
Protein Kinases ◽  
Mapk Pathway ◽  
Critical Role ◽  
Soft Agar ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinases ◽  
Oncogenic Ras ◽  
Ras Activation ◽  
Mitogen Activated Protein ◽  
Transforming Activity

Although substantial evidence supports a critical role for the activation of Raf-1 and mitogen-activated protein kinases (MAPKs) in oncogenic Ras-mediated transformation, recent evidence suggests that Ras may activate a second signaling pathway which involves the Ras-related proteins Rac1 and RhoA. Consequently, we used three complementary approaches to determine the contribution of Rac1 and RhoA function to oncogenic Ras-mediated transformation. First, whereas constitutively activated mutants of Rac1 and RhoA showed very weak transforming activity when transfected alone, their coexpression with a weakly transforming Raf-1 mutant caused a greater than 35-fold enhancement of transforming activity. Second, we observed that coexpression of dominant negative mutants of Rac1 and RhoA reduced oncogenic Ras transforming activity. Third, activated Rac1 and RhoA further enhanced oncogenic Ras-triggered morphologic transformation, as well as growth in soft agar and cell motility. Finally, we also observed that kinase-deficient MAPKs inhibited Ras transformation. Taken together, these data support the possibility that oncogenic Ras activation of Rac1 and RhoA, coupled with activation of the Raf/MAPK pathway, is required to trigger the full morphogenic and mitogenic consequences of oncogenic Ras transformation.

scholarly journals Growth Factor–induced p42/p44 MAPK Nuclear Translocation and Retention Requires Both MAPK Activation and Neosynthesis of Nuclear Anchoring Proteins

1998 ◽  
Vol 142 (3) ◽  
pp. 625-633 ◽  
Author(s):  
Philippe Lenormand ◽  
Jean-Marc Brondello ◽  
Anne Brunet ◽  
Jacques Pouysségur
Keyword(s):  
Nuclear Localization ◽  
Nuclear Translocation ◽  
Mapk Pathway ◽  
Mek Inhibitor ◽  
Nuclear Accumulation ◽  
Mapk Activation ◽  
Mitogen Activated Protein Kinases ◽  
Anchoring Proteins ◽  
Mitogen Activated Protein ◽  
Necessary And Sufficient

Mitogen-activated protein kinases (p42/p44 MAPK, also called Erk2 and Erk1) are key mediators of signal transduction from the cell surface to the nucleus. We have previously shown that the activation of p42/p44 MAPK required for transduction of mitogenic signaling is associated with a rapid nuclear translocation of these kinases. However, the means by which p42 and p44 MAPK translocate into the nucleus after cytoplasmic activation is still not understood and cannot simply be deduced from their protein sequences. In this study, we have demonstrated that activation of the p42/ p44 MAPK pathway was necessary and sufficient for triggering nuclear translocation of p42 and p44 MAPK. First, addition of the MEK inhibitor PD 98059, which blocks activation of the p42/p44 MAPK pathway, impedes the nuclear accumulation, whereas direct activation of the p42/p44 MAPK pathway by the chimera ΔRaf-1:ER is sufficient to promote nuclear accumulation of p42/p44 MAPK. In addition, we have shown that this nuclear accumulation of p42/p44 MAPK required the neosynthesis of short-lived proteins. Indeed, inhibitors of protein synthesis abrogate nuclear accumulation in response to serum and accelerate p42/p44 MAPK nuclear efflux under conditions of persistent p42/p44 MAPK activation. In contrast, inhibition of targeted proteolysis by the proteasome synergistically potentiated p42/p44 MAPK nuclear localization by nonmitogenic agonists and markedly prolonged nuclear localization of p42/p44 MAPK after mitogenic stimulation. We therefore conclude that the MAPK nuclear translocation requires both activation of the p42/p44 MAPK module and neosynthesis of short-lived proteins that we postulate to be nuclear anchors.

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