Activation of the p42 Mitogen-activated Protein Kinase Pathway Inhibits Cdc2 Activation and Entry into M-Phase in Cycling<i>Xenopus</i>Egg Extracts

Bitangcol, John C.; Chau, Andrew S.-S.; Stadnick, Ellamae; Lohka, Manfred J.; Dicken, Bryan; Shibuya, Ellen K.

doi:10.1091/mbc.9.2.451

Cited by 59 publications

(77 citation statements)

References 62 publications

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“…First, addition of Aur-A protein during interphase does not lead to a detectable increase in Mos (H. Wu and J.V.R., unpublished data). Second, addition of Mos or MAP kinase blocks mitotic entry rather than accelerating it (36,37). CPEB-dependent translation of cyclin B1 is required for mitotic entry in egg extracts (38) and overexpression of Aur-A enhances polyadenylation of cyclin mRNA in somatic cells (17).…”

Section: Discussionmentioning

confidence: 99%

Aurora A, mitotic entry, and spindle bipolarity

Liu

Ruderman

2006

Proc. Natl. Acad. Sci. U.S.A.

108

103

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The kinase Aurora-A (Aur-A), which is enriched at centrosomes, is required for centrosome maturation and accurate chromosome segregation, and recent work implicates centrosomes as sites where the earliest activation of cyclin B1-cdc2 occurs. Here, we have used Xenopus egg extracts to investigate Aur-A's contribution to cell cycle progression and spindle morphology in the presence or absence of centrosomes. We find that addition of active Aur-A accelerates cdc2 activation and mitotic entry. Depletion of endogenous Aur-A or addition of inactive Aur-A, which lead to monopolar spindles, delays but does not block mitotic entry. These effects on timing and spindle structure do not require the presence of centrosomes or chromosomes. The catalytic domain alone of Aur-A is sufficient to restore spindle bipolarity; additional N-terminal sequences function in mitotic timing.Aurora kinases ͉ G2͞M transition ͉ mitosis

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Section: Discussionmentioning

confidence: 99%

Aurora A, mitotic entry, and spindle bipolarity

Liu

Ruderman

2006

Proc. Natl. Acad. Sci. U.S.A.

108

103

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“…Destruction of cyclin B, a marker for the metaphase/anaphase transition, occurred between 90 and 95 min. The tyrosine-phosphorylated (active) form of MAPK first occurred around this time, which is important for the maintenance of chromosome condensation during the latter stages of mitosis (Bitangcol et al, 1998;Shibuya, 1998, 1999). MAPK phosphorylation increased and then dropped at 105-110 min, when chromosome decondensation was being completed, and the extract entered interphase of the second cell cycle.…”

Section: Oscillations In Phosphorylation Of Endogenous Cdc25c Proteinmentioning

confidence: 99%

Changes in Regulatory Phosphorylation of Cdc25C Ser287 and Wee1 Ser549 during Normal Cell Cycle Progression and Checkpoint Arrests

Stanford

Ruderman

2005

MBoC

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Entry into mitosis is catalyzed by cdc2 kinase. Previous work identified the cdc2-activating phosphatase cdc25C and the cdc2-inhibitory kinase wee1 as targets of the incomplete replication-induced kinase Chk1. Further work led to the model that checkpoint kinases block mitotic entry by inhibiting cdc25C through phosphorylation on Ser287 and activating wee1 through phosphorylation on Ser549. However, almost all conclusions underlying this idea were drawn from work using recombinant proteins. Here, we report that in the early Xenopus egg cell cycles, phosphorylation of endogenous cdc25C Ser287 is normally high during interphase and shows no obvious increase after checkpoint activation. By contrast, endogenous wee1 Ser549 phosphorylation is low during interphase and increases after activation of either the DNA damage or replication checkpoints; this is accompanied by a slight increase in wee1 kinase activity. Blocking mitotic entry by adding the catalytic subunit of PKA also results in increased wee1 Ser549 phosphorylation and maintenance of cdc25C Ser287 phosphorylation. These results argue that in response to checkpoint activation, endogenous wee1 is indeed a critical responder that functions by repressing the cdc2-cdc25C positive feedback loop. Surprisingly, endogenous wee1 Ser549 phosphorylation is highest during mitosis just after the peak of cdc2 activity. Treatments that block inactivation of cdc2 result in further increases in wee1 Ser549 phosphorylation, suggesting a previously unsuspected role for wee1 in mitosis. INTRODUCTIONEntry into mitosis is initiated by activation of cyclin B/cdc2. Preformed complexes of cyclin B/cdc2 accumulate during interphase, but their activity is repressed by inhibitory phosphorylations on cdc2 at Tyr15 (catalyzed by wee1 and myt1) and Thr14 (catalyzed by myt1). These phosphorylations are removed by the phosphatase cdc25C (reviewed in Berry and Gould, 1996;Lew and Kornbluth, 1996). Early work led to the conclusion that cdc2 and cdc25C activities both increase rapidly during the G 2 /M transition as the result of positive feedback loops between cyclin B/cdc2 and cdc25C, ultimately leading to the full activation of both cdc25C and cyclin B/cdc2 (Izumi et al., 1992;Hoffmann et al., 1993;Izumi and Maller, 1993;Strausfeld et al., 1994). The mechanisms that trigger this abrupt activation are still not well understood (Margolis and Kornbluth, 2004;Perdiguero and Nebreda, 2004).Over the past decade, there has been a large increase in the molecular understanding of how checkpoint pathways become activated, and how they affect the basic cell cycle regulatory machinery. Genetic and biochemical approaches have identified sensors that detect incompletely replicated or damaged DNA and that stimulate signal transduction pathways that lead to activation of the kinases Chk1 and Chk2/Cds1 (reviewed in Sancar et al., 2004). Both Chk1 and Chk2 can phosphorylate cdc25C on Ser287 (human Ser216), which creates a binding site for 14-3-3 proteins; this is thought to inhibit cdc25C activation and thus...

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“…In mitotic Xenopus egg extracts, MEK is active and required for normal mitotic progression (Abrieu et al, 1997;Walter et al, 1997;Bitangcol et al, 1998;Murakami and Vande Woude, 1998). MEK inhibition causes defects in both spindle formation (Horne and Guadagno, 2003) and spindle checkpoint control (Minshull et al, 1994;Takenaka et al, 1997;Chung and Chen, 2003).…”

Section: Introductionmentioning

confidence: 99%

Mitogen-activated Protein Kinase Kinase 1-dependent Golgi Unlinking Occurs in G₂Phase and Promotes the G₂/M Cell Cycle Transition

Feinstein

Linstedt

2007

MBoC

100

162

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Two controversies have emerged regarding the signaling pathways that regulate Golgi disassembly at the G2/M cell cycle transition. The first controversy concerns the role of mitogen-activated protein kinase activator mitogen-activated protein kinase kinase (MEK)1, and the second controversy concerns the participation of Golgi structure in a novel cell cycle “checkpoint.” A potential simultaneous resolution is suggested by the hypothesis that MEK1 triggers Golgi unlinking in late G2 to control G2/M kinetics. Here, we show that inhibition of MEK1 by RNA interference or by using the MEK1/2-specific inhibitor U0126 delayed the passage of synchronized HeLa cells into M phase. The MEK1 requirement for normal mitotic entry was abrogated if Golgi proteins were dispersed before M phase by treatment of cells with brefeldin A or if GRASP65, which links Golgi stacks into a ribbon network, was depleted. Imaging revealed that unlinking of the Golgi apparatus begins before M phase, is independent of cyclin-dependent kinase 1 activation, and requires MEK signaling. Furthermore, expression of the GRASP family member GRASP55 after alanine substitution of its MEK1-dependent mitotic phosphorylation sites inhibited both late G2 Golgi unlinking and the G2/M transition. Thus, MEK1 plays an in vivo role in Golgi reorganization, which regulates cell cycle progression.

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Activation of the p42 Mitogen-activated Protein Kinase Pathway Inhibits Cdc2 Activation and Entry into M-Phase in CyclingXenopusEgg Extracts

Cited by 59 publications

References 62 publications

Aurora A, mitotic entry, and spindle bipolarity

Aurora A, mitotic entry, and spindle bipolarity

Changes in Regulatory Phosphorylation of Cdc25C Ser287 and Wee1 Ser549 during Normal Cell Cycle Progression and Checkpoint Arrests

Mitogen-activated Protein Kinase Kinase 1-dependent Golgi Unlinking Occurs in G₂Phase and Promotes the G₂/M Cell Cycle Transition

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Activation of the p42 Mitogen-activated Protein Kinase Pathway Inhibits Cdc2 Activation and Entry into M-Phase in CyclingXenopusEgg Extracts

Cited by 59 publications

References 62 publications

Aurora A, mitotic entry, and spindle bipolarity

Aurora A, mitotic entry, and spindle bipolarity

Changes in Regulatory Phosphorylation of Cdc25C Ser287 and Wee1 Ser549 during Normal Cell Cycle Progression and Checkpoint Arrests

Mitogen-activated Protein Kinase Kinase 1-dependent Golgi Unlinking Occurs in G2Phase and Promotes the G2/M Cell Cycle Transition

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Mitogen-activated Protein Kinase Kinase 1-dependent Golgi Unlinking Occurs in G₂Phase and Promotes the G₂/M Cell Cycle Transition