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Iglesias-Romero AB, Soto T, Flor-Parra I, Salas-Pino S, Ruiz-Romero G, Gould KL, Cansado J, Daga RR. MAPK-dependent control of mitotic progression in S. pombe. BMC Biol 2024; 22:71. [PMID: 38523261 PMCID: PMC10962199 DOI: 10.1186/s12915-024-01865-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 03/08/2024] [Indexed: 03/26/2024] Open
Abstract
BACKGROUND Mitogen-activated protein kinases (MAPKs) preserve cell homeostasis by transducing physicochemical fluctuations of the environment into multiple adaptive responses. These responses involve transcriptional rewiring and the regulation of cell cycle transitions, among others. However, how stress conditions impinge mitotic progression is largely unknown. The mitotic checkpoint is a surveillance mechanism that inhibits mitotic exit in situations of defective chromosome capture, thus preventing the generation of aneuploidies. In this study, we investigate the role of MAPK Pmk1 in the regulation of mitotic exit upon stress. RESULTS We show that Schizosaccharomyces pombe cells lacking Pmk1, the MAP kinase effector of the cell integrity pathway (CIP), are hypersensitive to microtubule damage and defective in maintaining a metaphase arrest. Epistasis analysis suggests that Pmk1 is involved in maintaining spindle assembly checkpoint (SAC) signaling, and its deletion is additive to the lack of core SAC components such as Mad2 and Mad3. Strikingly, pmk1Δ cells show up to twofold increased levels of the anaphase-promoting complex (APC/C) activator Cdc20Slp1 during unperturbed growth. We demonstrate that Pmk1 physically interacts with Cdc20Slp1 N-terminus through a canonical MAPK docking site. Most important, the Cdc20Slp1 pool is rapidly degraded in stressed cells undergoing mitosis through a mechanism that requires MAPK activity, Mad3, and the proteasome, thus resulting in a delayed mitotic exit. CONCLUSIONS Our data reveal a novel function of MAPK in preventing mitotic exit and activation of cytokinesis in response to stress. The regulation of Cdc20Slp1 turnover by MAPK Pmk1 provides a key mechanism by which the timing of mitotic exit can be adjusted relative to environmental conditions.
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Affiliation(s)
| | - Terersa Soto
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, 30071, Spain
| | - Ignacio Flor-Parra
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Seville, 41013, Spain
| | - Silvia Salas-Pino
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Seville, 41013, Spain
| | - Gabriel Ruiz-Romero
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Seville, 41013, Spain
| | - Kathleen L Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA
| | - José Cansado
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, 30071, Spain.
| | - Rafael R Daga
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Seville, 41013, Spain.
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2
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Tan T, Wu C, Liu B, Pan BF, Hawke DH, Su Z, Liu S, Zhang W, Wang R, Lin SH, Kuang J. Revisiting the multisite phosphorylation that produces the M-phase supershift of key mitotic regulators. Mol Biol Cell 2022; 33:ar115. [PMID: 35976701 PMCID: PMC9635296 DOI: 10.1091/mbc.e22-04-0118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The term M-phase supershift denotes the phosphorylation-dependent substantial increase in the apparent molecular weight of numerous proteins of varied biological functions during M-phase induction. Although the M-phase supershift of multiple key mitotic regulators has been attributed to the multisite phosphorylation catalyzed by the Cdk1/cyclin B/Cks complex, this view is challenged by multiple lines of paradoxical observations. To solve this problem, we reconstituted the M-phase supershift of Xenopus Cdc25C, Myt1, Wee1A, APC3 and Greatwall in Xenopus egg extracts and characterized the supershift-producing phosphorylations. Our results demonstrate that their M-phase supershifts are each due to simultaneous phosphorylation of a considerable portion of S/T/Y residues in a long intrinsically disordered region that is enriched in both S/T residues and S/TP motifs. Although the major mitotic kinases in Xenopus egg extracts, Cdk1, MAPK, Plx1 and RSK2, are able to phosphorylate the five mitotic regulators, they are neither sufficient nor required to produce the M-phase supershift. Accordingly, inhibition of the four major mitotic kinase activities in Xenopus oocytes did not inhibit the M-phase supershift in okadaic acid-induced oocyte maturation. These findings indicate that the M-phase supershift is produced by a previously unrecognized category of mitotic phosphorylation that likely plays important roles in M-phase induction.
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Affiliation(s)
- Tan Tan
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.,Department of Biochemistry and Molecular Biology, Hengyang Medical School, The University of South China, Hengyang, Hunan 421001, China
| | - Chuanfen Wu
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Boye Liu
- Key Laboratory for Biodiversity and Ecological Engineering of Ministry of Education
| | - Bih-Fang Pan
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - David H Hawke
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Zehao Su
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Shuaishuai Liu
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Wei Zhang
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Ruoning Wang
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sue-Hwa Lin
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jian Kuang
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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3
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Bisht J, LeValley P, Noren B, McBride R, Kharkar P, Kloxin A, Gatlin J, Oakey J. Light-inducible activation of cell cycle progression in Xenopus egg extracts under microfluidic confinement. LAB ON A CHIP 2019; 19:3499-3511. [PMID: 31544194 PMCID: PMC7819639 DOI: 10.1039/c9lc00569b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cell-free Xenopus egg extract is a widely used and biochemically tractable model system that allows recapitulation and elucidation of fundamental cellular processes. Recently, the introduction of microfluidic extract manipulation has enabled compartmentalization of bulk extract and a newfound ability to study organelles on length scales that recapitulate key features of cellular morphology. While the microfluidic confinement of extracts has produced a compelling platform for the in vitro study of cell processes at physiologically-relevant length scales, it also imposes experimental limitations by restricting dynamic control over extract properties. Here, we introduce photodegradable polyethylene glycol (PEG) hydrogels as a vehicle to passively and selectively manipulate extract composition through the release of proteins encapsulated within the hydrogel matrix. Photopatterned PEG hydrogels, passive to both extract and encapsulated proteins, serve as protein depots within microfluidic channels, which are subsequently flooded with extract. Illumination by ultraviolet light (UV) degrades the hydrogel structures and releases encapsulated protein. We show that an engineered fluorescent protein with a nuclear localization signal (GST-GFP-NLS) retains its ability to localize within nearby nuclei following UV-induced release from hydrogel structures. When diffusion is considered, the kinetics of nuclear accumulation are similar to those in experiments utilizing conventional, bulk fluid handling. Similarly, the release of recombinant cyclin B Δ90, a mutant form of the master cell cycle regulator cyclin B which lacks the canonical destruction box, was able to induce the expected cell cycle transition from interphase to mitosis. This transition was confirmed by the observation of nuclear envelope breakdown (NEBD), a phenomenological hallmark of mitosis, and the induction of mitosis-specific biochemical markers. This approach to extract manipulation presents a versatile and customizable route to regulating the spatial and temporal dynamics of cellular events in microfluidically confined cell-free extracts.
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Affiliation(s)
- Jitender Bisht
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071
- Cell Organization and Division Group, Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
| | - Paige LeValley
- Department of Chemical Engineering, University of Wyoming, Laramie, WY 82071
- Cell Organization and Division Group, Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716
| | - Benjamin Noren
- Department of Chemical Engineering, University of Wyoming, Laramie, WY 82071
- Cell Organization and Division Group, Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
| | - Ralph McBride
- Department of Chemical Engineering, University of Wyoming, Laramie, WY 82071
| | - Prathamesh Kharkar
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716
| | - April Kloxin
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716
| | - Jesse Gatlin
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071
- Cell Organization and Division Group, Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
| | - John Oakey
- Department of Chemical Engineering, University of Wyoming, Laramie, WY 82071
- Cell Organization and Division Group, Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
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4
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Tsai TYC, Theriot JA, Ferrell JE. Changes in oscillatory dynamics in the cell cycle of early Xenopus laevis embryos. PLoS Biol 2014; 12:e1001788. [PMID: 24523664 PMCID: PMC3921120 DOI: 10.1371/journal.pbio.1001788] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 12/31/2013] [Indexed: 11/19/2022] Open
Abstract
During the early development of Xenopus laevis embryos, the first mitotic cell cycle is long (∼85 min) and the subsequent 11 cycles are short (∼30 min) and clock-like. Here we address the question of how the Cdk1 cell cycle oscillator changes between these two modes of operation. We found that the change can be attributed to an alteration in the balance between Wee1/Myt1 and Cdc25. The change in balance converts a circuit that acts like a positive-plus-negative feedback oscillator, with spikes of Cdk1 activation, to one that acts like a negative-feedback-only oscillator, with a shorter period and smoothly varying Cdk1 activity. Shortening the first cycle, by treating embryos with the Wee1A/Myt1 inhibitor PD0166285, resulted in a dramatic reduction in embryo viability, and restoring the length of the first cycle in inhibitor-treated embryos with low doses of cycloheximide partially rescued viability. Computations with an experimentally parameterized mathematical model show that modest changes in the Wee1/Cdc25 ratio can account for the observed qualitative changes in the cell cycle. The high ratio in the first cycle allows the period to be long and tunable, and decreasing the ratio in the subsequent cycles allows the oscillator to run at a maximal speed. Thus, the embryo rewires its feedback regulation to meet two different developmental requirements during early development.
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Affiliation(s)
- Tony Y.-C. Tsai
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, United States of America
| | - Julie A. Theriot
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, United States of America
| | - James E. Ferrell
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
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5
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Guo W, Hao B, Wang Q, Lu Y, Yue J. Requirement of B-Raf, C-Raf, and A-Raf for the growth and survival of mouse embryonic stem cells. Exp Cell Res 2013; 319:2801-11. [DOI: 10.1016/j.yexcr.2013.09.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 08/22/2013] [Accepted: 09/09/2013] [Indexed: 12/31/2022]
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6
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Intracellular and extracellular pH and Ca are bound to control mitosis in the early sea urchin embryo via ERK and MPF activities. PLoS One 2013; 8:e66113. [PMID: 23785474 PMCID: PMC3681939 DOI: 10.1371/journal.pone.0066113] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 05/01/2013] [Indexed: 11/19/2022] Open
Abstract
Studies aiming to predict the impact on marine life of ocean acidification and of altered salinity have shown altered development in various species including sea urchins. We have analyzed how external Na, Ca, pH and bicarbonate control the first mitotic divisions of sea urchin embryos. Intracellular free Ca (Cai) and pH (pHi) and the activities of the MAP kinase ERK and of MPF regulate mitosis in various types of cells including oocytes and early embryos. We found that intracellular acidification of fertilized eggs by Na-acetate induces a huge activation of ERK at time of mitosis. This also stops the cell cycle and leads to cell death, which can be bypassed by treatment with the MEK inhibitor U0126. Similar intracellular acidification induced in external medium containing low sodium or 5-(N-Methyl-N-isobutyl) amiloride, an inhibitor of the Na+/H+ exchanger, also stops the cell cycle and leads to cell death. In that case, an increase in Cai and in the phosphorylation of tyr-cdc2 occurs during mitosis, modifications that depend on external Ca. Our results indicate that the levels of pHi and Cai determine accurate levels of Ptyr-Cdc2 and P-ERK capable of ensuring progression through the first mitotic cycles. These intracellular parameters rely on external Ca, Na and bicarbonate, alterations of which during climate changes could act synergistically to perturb the early marine life.
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7
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Xu L, Liu T, Han F, Zong Z, Wang G, Yu B, Zhang J. AURKB and MAPK involvement in the regulation of the early stages of mouse zygote development. SCIENCE CHINA-LIFE SCIENCES 2012; 55:47-56. [PMID: 22314491 DOI: 10.1007/s11427-012-4264-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 11/15/2011] [Indexed: 01/05/2023]
Abstract
Aurora kinases have become a hot topic for research as they have been found to play an important role in various stages of mitotic cell division and to participate in malignant conversions of tumors. The participation of Aurora kinases in the regulation of oocyte meiosis has been recently reported, but their participation in mammalian early embryonic development remained unclear. The object of our study was to establish the spatio-temporal expression pattern of Aurora kinase B (AURKB) in mouse zygotes during the first cleavage, to reveal its functions in the early development of mouse zygotes, and to define the involvement of AURKB in mitogen-activated protein kinase (MAPK) signaling. Our results showed that in mouse zygotes AURKB expression increased in G1 phase and peaked in M phase. AURKB protein distribution was found to be in association with nuclei and distributed throughout the cytoplasm in a cell cycle-dependent manner. Functional disruption of AURKB resulted in abnormal division phenotypes or mitotic impairments. U0126, a specific mitogen-activated protein kinase kinase (MEK) inhibitor, caused significantly altered morphologies of early embryos together with a decrease in protein expression and kinase activity of AURKB. Our results indicated that the activity of AURKB was required for regulating multiple stages of mitotic progression in the early development of mouse zygotes and was correlated with the activation of the MAPK pathway.
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Affiliation(s)
- Lin Xu
- Department of Biochemistry and Molecular Biology, China Medical University, Shenyang 110001, China
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8
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Rsk-mediated phosphorylation and 14-3-3ɛ binding of Apaf-1 suppresses cytochrome c-induced apoptosis. EMBO J 2012; 31:1279-92. [PMID: 22246185 DOI: 10.1038/emboj.2011.491] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 12/14/2011] [Indexed: 01/13/2023] Open
Abstract
Many pro-apoptotic signals trigger mitochondrial cytochrome c release, leading to caspase activation and ultimate cellular breakdown. Cell survival pathways, including the mitogen-activated protein kinase (MAPK) cascade, promote cell viability by impeding mitochondrial cytochrome c release and by inhibiting subsequent caspase activation. Here, we describe a mechanism for the inhibition of cytochrome c-induced caspase activation by MAPK signalling, identifying a novel mode of apoptotic regulation exerted through Apaf-1 phosphorylation by the 90-kDa ribosomal S6 kinase (Rsk). Recruitment of 14-3-3ɛ to phosphorylated Ser268 impedes the ability of cytochrome c to nucleate apoptosome formation and activate downstream caspases. High endogenous levels of Rsk in PC3 prostate cancer cells or Rsk activation in other cell types promoted 14-3-3ɛ binding to Apaf-1 and rendered the cells insensitive to cytochrome c, suggesting a potential role for Rsk signalling in apoptotic resistance of prostate cancers and other cancers with elevated Rsk activity. Collectively, these results identify a novel locus of apoptosomal regulation wherein MAPK signalling promotes Rsk-catalysed Apaf-1 phosphorylation and consequent binding of 14-3-3ɛ, resulting in decreased cellular responsiveness to cytochrome c.
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9
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Sturm OE, Orton R, Grindlay J, Birtwistle M, Vyshemirsky V, Gilbert D, Calder M, Pitt A, Kholodenko B, Kolch W. The mammalian MAPK/ERK pathway exhibits properties of a negative feedback amplifier. Sci Signal 2010; 3:ra90. [PMID: 21177493 DOI: 10.1126/scisignal.2001212] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Three-tiered kinase modules, such as the Raf-MEK (mitogen-activated or extracellular signal-regulated protein kinase kinase)-ERK (extracellular signal-regulated kinase) mitogen-activated protein kinase pathway, are widespread in biology, suggesting that this structure conveys evolutionarily advantageous properties. We show that the three-tiered kinase amplifier module combined with negative feedback recapitulates the design principles of a negative feedback amplifier (NFA), which is used in electronic circuits to confer robustness, output stabilization, and linearization of nonlinear signal amplification. We used mathematical modeling and experimental validation to demonstrate that the ERK pathway has properties of an NFA that (i) converts intrinsic switch-like activation kinetics into graded linear responses, (ii) conveys robustness to changes in rates of reactions within the NFA module, and (iii) stabilizes outputs in response to drug-induced perturbations of the amplifier. These properties determine biological behavior, including activation kinetics and the response to drugs.
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Affiliation(s)
- Oliver E Sturm
- Department of Computing Science, University of Glasgow, Glasgow G12 8QQ, UK.
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10
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Borysov SI, Guadagno TM. A novel role for Cdk1/cyclin B in regulating B-raf activation at mitosis. Mol Biol Cell 2008; 19:2907-15. [PMID: 18434602 DOI: 10.1091/mbc.e07-07-0679] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
MAPK activity is important during mitosis for spindle assembly and maintenance of the spindle checkpoint arrest. We previously identified B-Raf as a critical activator of the MAPK cascade during mitosis in Xenopus egg extracts and showed that B-Raf activation is regulated in an M-phase-dependent manner. The mechanism that mediates B-Raf activation at mitosis has not been elucidated. Interestingly, activation of 95-kDa B-Raf at mitosis does not require phosphorylation of Thr-599 and Ser-602 residues (Thr-633 and Ser-636 in Xenopus B-Raf), previously shown to be essential for B-Raf activation by Ras. Instead, we provide evidence for Cdk1/cyclin B in mediating mitotic activation of B-Raf. In particular, Cdk1/cyclin B complexes associate with B-Raf at mitosis in Xenopus egg extracts and contribute to its phosphorylation. Mutagenesis and in vitro kinase assays demonstrated that Cdk1/cyclin B directly phosphorylates B-Raf at Serine-144, which is part of a conserved Cdk1 preferential consensus site (S(144)PQK). Importantly, phosphorylation of Ser-144 is absolutely required for mitotic activation of B-Raf and subsequent activation of the MAPK cascade. However, substitution of a phospho-mimicking amino acid at Ser-144 failed to produce a constitutive active B-Raf indicating that, in addition of Ser-144 phosphorylation, other regulatory events may be needed to activate B-Raf at mitosis. Taken together, our data reveal a novel cell cycle mechanism for activating the B-Raf/MEK/MAPK cascade.
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Affiliation(s)
- Sergiy I Borysov
- Molecular Oncology Program, H. Lee Moffitt Cancer and Research Institute, Tampa, FL 33612, USA
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11
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Wang R, He G, Nelman-Gonzalez M, Ashorn CL, Gallick GE, Stukenberg PT, Kirschner MW, Kuang J. NEDD4-1 is a proto-oncogenic ubiquitin ligase for PTEN. Cell 2007; 128:1119-32. [PMID: 17382881 DOI: 10.1016/j.cell.2006.11.053] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Revised: 08/31/2006] [Accepted: 11/21/2006] [Indexed: 02/08/2023]
Abstract
The tumor suppressor PTEN, a critical regulator for multiple cellular processes, is mutated or deleted frequently in various human cancers. Subtle reductions in PTEN expression levels have profound impacts on carcinogenesis. Here we show that PTEN level is regulated by ubiquitin-mediated proteasomal degradation, and purified its ubiquitin ligase as HECT-domain protein NEDD4-1. In cells NEDD4-1 negatively regulates PTEN stability by catalyzing PTEN polyubiquitination. Consistent with the tumor-suppressive role of PTEN, overexpression of NEDD4-1 potentiated cellular transformation. Strikingly, in a mouse cancer model and multiple human cancer samples where the genetic background of PTEN was normal but its protein levels were low, NEDD4-1 was highly expressed, suggesting that aberrant upregulation of NEDD4-1 can posttranslationally suppress PTEN in cancers. Elimination of NEDD4-1 expression inhibited xenotransplanted tumor growth in a PTEN-dependent manner. Therefore, NEDD4-1 is a potential proto-oncogene that negatively regulates PTEN via ubiquitination, a paradigm analogous to that of Mdm2 and p53.
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Affiliation(s)
- Ruoning Wang
- Department of Experimental Therapeutics, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
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12
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Cui XS, Li XY, Yin XJ, Kong IK, Kang JJ, Kim NH. Maternal gene transcription in mouse oocytes: genes implicated in oocyte maturation and fertilization. J Reprod Dev 2006; 53:405-18. [PMID: 17179655 DOI: 10.1262/jrd.18113] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Maternal gene expression is an important biological process in oocyte maturation and early cleavage. To gain insights into oocyte maturation and early embryo development, we used microarray analysis to compare the gene expression profiles of germinal vesicle (GV)- and metaphase II (MII)-stage oocytes. The differences in spot intensities were normalized and grouped using the Avadis Prophetic software platform. Of the 12164 genes examined, we found 1682 genes with more highly expression in GV-stage oocytes than in MII-stage oocytes, while 1936 genes were more highly expressed in MII-stage oocytes (P<0.05). The genes were grouped on the basis of the Panther classification system according to their involvement in particular biological processes. The genes that were up-regulated in GV oocytes were more likely to be involved in protein metabolism and modification, the mitotic cell cycle, electron transport, or fertilization or belong to the microtubule/cytoskeletal protein family. The genes specifically upregulated in the MII oocytes were more likely to be involved in DNA replication, amino acid metabolism, or expression of G protein-coupled receptors and signaling molecules. Identification of genes that are preferentially expressed at particular oocyte maturation stages provides insights into the complex gene regulatory networks that drive oocyte maturation and fertilization.
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Affiliation(s)
- Xiang-Shun Cui
- National Research Laboratory of Molecular Embryology, Department of Animal Science, Chungbuk National University, Cheongju, Korea
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13
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Mogila V, Xia F, Li WX. An intrinsic cell cycle checkpoint pathway mediated by MEK and ERK in Drosophila. Dev Cell 2006; 11:575-82. [PMID: 17011495 PMCID: PMC3095892 DOI: 10.1016/j.devcel.2006.08.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Revised: 07/06/2006] [Accepted: 08/22/2006] [Indexed: 11/29/2022]
Abstract
Cell cycle checkpoints are surveillance mechanisms that safeguard genome integrity. While the extrinsic pathways that halt the cell cycle in response to DNA damages have been well documented, the intrinsic pathways that ensure orderly progression of cell cycle events are not well understood. We demonstrate that Drosophila MEK and ERK constitute an essential intrinsic checkpoint pathway that restrains cell cycle progression in the absence of DNA damage and also responds to ionizing radiation to arrest the cell cycle. Embryos lacking MEK exhibit faster and extra division cycles and fail to undergo timely midblastula transition (MBT) or arrest following ionizing radiation. Conversely, constitutively activated MEK causes cell cycle arrest. Further, MEK activation in the early embryo is cell cycle-dependent and Raf independent and increases in response to ionizing radiation or in the absence of Chk1. Thus, MEK/ERK activation is required for multiple checkpoints and is essential for orderly cell cycle progression.
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Affiliation(s)
- Vladic Mogila
- Department of Biomedical Genetics University of Rochester Medical Center Rochester, New York 14642
| | - Fan Xia
- Department of Biomedical Genetics University of Rochester Medical Center Rochester, New York 14642
| | - Willis X. Li
- Department of Biomedical Genetics University of Rochester Medical Center Rochester, New York 14642
- Correspondence:
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14
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Abstract
The protein kinase Mos is responsible for the activation of MEK1 and p42 mitogen-activated protein kinase during Xenopus oocyte maturation and during mitosis in Xenopus egg extracts. Here we show that the activation of Mos depends upon the phosphorylation of Ser 3, a residue previously implicated in the regulation of Mos stability; the dephosphorylation of Ser 105, a previously unidentified phosphorylation site conserved in Mos proteins; and the regulated dissociation of Mos from CK2beta. Mutation of Ser 3 to alanine and/or mutation of Ser 105 to glutamate produces a Mos protein that is defective for M-phase activation, as assessed by in vitro kinase assays, and defective for induction of oocyte maturation and maintenance of the spindle assembly checkpoint in extracts. Interestingly, Ser 105 is situated at the beginning of helix alphaC in the N-terminal lobe of the Mos kinase domain. Changes in the orientation of this helix have been previously implicated in the activation of Cdk2 and Src family tyrosine kinases. Our work suggests that Ser 105 dephosphorylation represents a novel mechanism for reorienting helix alphaC.
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Affiliation(s)
- Jianbo Yue
- Stanford University School of Medicine, Department of Molecular Pharmacology, CCSR Room 3155, Stanford, CA 94305-5174, USA.
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15
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Borysov SI, Cheng AWM, Guadagno TM. B-Raf Is Critical For MAPK Activation during Mitosis and Is Regulated in an M Phase-dependent Manner in Xenopus Egg Extracts. J Biol Chem 2006; 281:22586-96. [PMID: 16762920 DOI: 10.1074/jbc.m601432200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Activation of the MAPK cascade during mitosis is critical for spindle assembly and normal mitotic progression. The underlying regulatory mechanisms that control activation of the MEK/MAPK cascade during mitosis are poorly understood. Here we purified and characterized the MEK kinase activity present in Xenopus M phase-arrested egg extracts. Our results show that B-Raf was the critical MEK kinase required for M phase activation of the MAPK pathway. Consistent with this, B-Raf was activated and underwent hyperphosphorylation in an M phase-dependent manner. Interestingly B-Raf hyperphosphorylation at mitosis occurred, at least in part, as a consequence of a feedback loop involving MAPK-mediated phosphorylation within a conserved C-terminal SPKTP motif. The kinase activity of a B-Raf mutant defective at both phosphorylation sites was substantially greater than its wild type counterpart when incubated in Xenopus M phase egg extracts. Furthermore suppression of MAPK feedback at mitosis enhanced B-Raf activity, whereas constitutive activation of MAPK at mitosis strongly suppressed B-Raf activity. These results suggest that feedback phosphorylation by MAPK negatively regulates B-Raf activity at mitosis. Collectively our data demonstrate for the first time a role for B-Raf at mitosis and provide new insight into understanding the regulation and function of B-Raf during cell proliferation.
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Affiliation(s)
- Sergiy I Borysov
- Molecular Oncology Program, Department of Interdisciplinary Oncology, H. Lee Moffitt Comprehensive Cancer Center and Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, Florida 33612, USA
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Bergstralh DT, Ting JPY. Microtubule stabilizing agents: Their molecular signaling consequences and the potential for enhancement by drug combination. Cancer Treat Rev 2006; 32:166-79. [PMID: 16527420 DOI: 10.1016/j.ctrv.2006.01.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Revised: 01/10/2006] [Accepted: 01/10/2006] [Indexed: 11/28/2022]
Abstract
Microtubule stabilization by chemotherapy is a powerful weapon in the war against cancer. Disruption of the mitotic spindle activates a number of signaling pathways, with consequences that may protect the cell or lead to its death via apoptosis. Taxol, the first microtubule stabilizing drug to be identified, has been utilized successfully in the treatment of solid tumors for two decades. Several features, however, make this drug less than ideal, and the search for next generation stabilizing drugs with increased efficacy has been intense and fruitful. Microtubule stabilizing agents (MSAs), including the taxanes, the epothilones, discodermolide, laulimalide, and eleutherobin, form an important and expanding family of chemotherapeutic agents. A strong understanding of their molecular signaling consequences is essential to their value, particularly in regard to their potential for combinatorial chemotherapy - the use of multiple agents to enhance the efficacy of cancer treatment. Here we present a critical review of research on the signaling mechanisms induced by MSAs, their relevance to apoptosis, and their potential for exploitation by combinatorial therapy.
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Affiliation(s)
- Daniel T Bergstralh
- Lineberger Comprehensive Cancer Center, Curriculum in Genetics and Molecular Biology, Campus Box #7295, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295, USA
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Yue J, Xiong W, Ferrell JE. B-Raf and C-Raf are required for Ras-stimulated p42 MAP kinase activation in Xenopus egg extracts. Oncogene 2006; 25:3307-15. [PMID: 16434971 DOI: 10.1038/sj.onc.1209354] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During mitosis, a select pool of MEK1 and p42/p44 MAPK becomes activated at the kinetochores and spindle poles, without substantial activation of the bulk of the cytoplasmic p42/p44 MAPK. Recently, we set out to identify the MAP kinase kinase kinase (MAPKKK) responsible for this mitotic activation, using cyclin-treated Xenopus egg extracts as a model system, and presented evidence that Mos was the relevant MAPKKK . However, a second MAPKKK distinct from Mos was readily detectable as well. Here, we partially purify this second MAPKKK and identify it as B-Raf. No changes in the activity of B-Raf were detectable during progesterone-induced oocyte maturation, after egg fertilization, or during the early embryonic cell cycle, arguing against a role for B-Raf in the mitotic activation of MEK1 and p42 MAPK. Ras proteins can bring about activation of MEK1 and p42 MAPK in extracts, and Ras may contribute to signaling from the classical progesterone receptor during oocyte maturation and from receptor tyrosine kinases during early embryogenesis. We found that both B-Raf and C-Raf, but not Mos, are required for Ras-induced MEK1 and p42 MAPK activation. These data indicate that two upstream stimuli, active Ras and active Cdc2, utilize different MAPKKKs to activate MEK1 and p42 MAPK.
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Affiliation(s)
- J Yue
- Department of Molecular Pharmacology, Stanford University, CA 94305-5174, USA.
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Han S, Zhou V, Pan S, Liu Y, Hornsby M, McMullan D, Klock HE, Haugen J, Lesley SA, Gray N, Caldwell J, Gu XJ. Identification of coumarin derivatives as a novel class of allosteric MEK1 inhibitors. Bioorg Med Chem Lett 2005; 15:5467-73. [PMID: 16199156 DOI: 10.1016/j.bmcl.2005.08.097] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Revised: 08/26/2005] [Accepted: 08/29/2005] [Indexed: 10/25/2022]
Abstract
A homogenous TR-FRET-based in vitro coupling assay for the MAP3Ks-MEK1-ERK2 kinase cascade was established and was used to screen for inhibitors of the ERK/MAPK pathway. A series of coumarin derivatives were identified from the screen. These compounds potently inhibit the activation of the unactivated human MEK1 by upstream MAP3Ks (including BRAF and COT), but do not inhibit the activity of the activated MEK1. In addition, the potency of these compounds in inhibiting MEK1 activation is not affected by varying the ATP concentration, suggesting that these inhibitors are not competitive with ATP. As expected, the coumarin compounds potently inhibit LPS-induced TNFalpha production and ERK phosphorylation in THP-1 cells, with the most potent compound having an IC(50) of 90nM. Molecular modeling studies suggest that these coumarins bind to an allosteric site in the inactive conformation of MEK1. This site has been shown to be utilized by the biarylamine series of MEK inhibitors such as PD318088. Very interestingly, the identified coumarin derivatives are almost identical to a series of inhibitors recently reported that block LPS-induced TNFalpha production. Our findings have therefore raised the possibility that other naturally occurring or synthetic coumarins with anti-cancer and anti-inflammatory activities might exert their biological function through the inhibition of MEK1.
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Affiliation(s)
- Shulin Han
- Genomics Institute of the Novartis Research Foundation (GNF), 10675 John Jay Hopkins Drive, San Diego, CA 92121, USA
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19
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Philipova R, Larman MG, Leckie CP, Harrison PK, Groigno L, Whitaker M. Inhibiting MAP kinase activity prevents calcium transients and mitosis entry in early sea urchin embryos. J Biol Chem 2005; 280:24957-67. [PMID: 15843380 PMCID: PMC3292879 DOI: 10.1074/jbc.m414437200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A transient calcium increase triggers nuclear envelope breakdown (mitosis entry) in sea urchin embryos. Cdk1/cyclin B kinase activation is also known to be required for mitosis entry. More recently, MAP kinase activity has also been shown to increase during mitosis. In sea urchin embryos, both kinases show a similar activation profile, peaking at the time of mitosis entry. We tested whether the activity of both kinases is required for mitosis entry and whether either kinase controls mitotic calcium signals. We found that reducing the activity of either mitotic kinase prevents nuclear envelope breakdown, despite the presence of a calcium transient, when cdk1/cyclin B kinase activity is alone inhibited. When MAP kinase activity alone was inhibited, the calcium signal was absent, suggesting that MAP kinase activity is required to generate the calcium transient that triggers nuclear envelope breakdown. However, increasing intracellular free calcium by microinjection of calcium buffers or InsP(3) while MAP kinase was inhibited did not itself induce nuclear envelope breakdown, indicating that additional MAP kinase-regulated events are necessary. After MAP kinase inhibition early in the cell cycle, the early events of the cell cycle (pronuclear migration/fusion and DNA synthesis) were unaffected, but chromosome condensation and spindle assembly are prevented. These data indicate that in sea urchin embryos, MAP kinase activity is part of a signaling complex alongside two components previously shown to be essential for entry into mitosis: the calcium transient and the increase in cdk1/cyclinB kinase activity.
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Affiliation(s)
- Rada Philipova
- Institute of Cell and Molecular Biosciences, Faculty of Medical Sciences, University of Newcastle upon Tyne, NE2 4HH, UK
| | - Mark G. Larman
- Institute of Cell and Molecular Biosciences, Faculty of Medical Sciences, University of Newcastle upon Tyne, NE2 4HH, UK
| | - Calum P. Leckie
- Institute of Cell and Molecular Biosciences, Faculty of Medical Sciences, University of Newcastle upon Tyne, NE2 4HH, UK
| | - Patrick K. Harrison
- Institute of Cell and Molecular Biosciences, Faculty of Medical Sciences, University of Newcastle upon Tyne, NE2 4HH, UK
| | - Laurence Groigno
- Institute of Cell and Molecular Biosciences, Faculty of Medical Sciences, University of Newcastle upon Tyne, NE2 4HH, UK
| | - Michael Whitaker
- Institute of Cell and Molecular Biosciences, Faculty of Medical Sciences, University of Newcastle upon Tyne, NE2 4HH, UK
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Zhang WL, Huitorel P, Glass R, Fernandez-Serra M, Arnone MI, Chiri S, Picard A, Ciapa B. A MAPK pathway is involved in the control of mitosis after fertilization of the sea urchin egg. Dev Biol 2005; 282:192-206. [PMID: 15936340 DOI: 10.1016/j.ydbio.2005.03.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 01/26/2005] [Accepted: 03/12/2005] [Indexed: 11/28/2022]
Abstract
Activation and role of mitogen-activated protein (MAP) kinase (MAPK) during mitosis are still matters of controversy in early embryos. We report here that an ERK-like protein is present and highly phosphorylated in unfertilized sea urchin eggs. This MAPK becomes dephosphorylated after fertilization and a small pool of it is transiently reactivated during mitosis. The phosphorylated ERK-like protein is localized to the nuclear region and then to the mitotic poles and the mitotic spindle. Treatment of eggs after fertilization with two different MEK inhibitors, PD 98059 and U0126, at low concentrations capable to selectively induce dephosphorylation of this ERK-like protein, or expression of a dominant-negative MEK1/2, perturbed mitotic progression. Our results suggest that an ERK-like cascade is part of a control mechanism that regulates mitotic spindle formation and the attachment of chromosomes to the spindle during the first mitosis of the sea urchin embryo.
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Affiliation(s)
- Wen Ling Zhang
- UMR 7622 CNRS, Université Paris 6, 9 Quai St Bernard, Bât C, 5(e) étage, case 24, 75252 Paris cedex 05, France
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