Okadaic Acid Induces Spindle Lengthening and Disrupts the Interaction of Microtubules with the Kinetochores in Metaphase II-Arrested Mouse Oocytes

Pennart, H. de; Verlhac, Marie‐Hélène; Cibert, Christian; Maria, Angélica Santa; Maro, Bernard

doi:10.1006/dbio.1993.1121

Cited by 26 publications

(8 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…PP2A and Microtubules-The dramatic action of OA on spindle-associated microtubules, which led to spindle elongation and eventual complete dissolution, has previously been observed in oocytes (26,69). We found that the longer-term action of OA in inducing spindle disassembly, normally observed by 4 h, could be prevented by expression of ⌬90 cyclin B1, suggesting that some of the effects of OA on spindle morphology were due to changes in CDK1 activity.…”

Section: Discussionsupporting

confidence: 56%

See 1 more Smart Citation

Essential Role of Protein Phosphatase 2A in Metaphase II Arrest and Activation of Mouse Eggs Shown by Okadaic Acid, Dominant Negative Protein Phosphatase 2A, and FTY720

Chang¹,

Jennings

Stewart

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

Vertebrate eggs arrest at second meiotic metaphase. The fertilizing sperm causes meiotic exit through Ca 2؉ -mediated activation of the anaphase-promoting complex/cyclosome (APC/ C). Although the loss in activity of the M-phase kinase CDK1 is known to be an essential downstream event of this process, the contribution of phosphatases to arrest and meiotic resumption is less apparent, especially in mammals. Therefore, we explored the role of protein phosphatase 2A (PP2A) in mouse eggs using pharmacological inhibition and activation as well as a functionally dominant-negative catalytic PP2A subunit (dn-PP2Ac-L199P) coupled with live cell imaging. We observed that PP2A inhibition using okadaic acid induced events normally observed at fertilization: degradation of the APC/C substrates cyclin B1 and securin resulting from loss of the APC/C inhibitor Emi2. Although sister chromatids separated, chromatin remained condensed, and polar body extrusion was blocked as a result of a rapid spindle disruption, which could be ameliorated by nondegradable cyclin B1, suggesting that spindle integrity was affected by CDK1 loss. Similar cell cycle effects to okadaic acid were also observed using dominant-negative PP2Ac. Preincubation of eggs with the PP2A activator FTY720 could block many of the actions of okadaic acid, including Emi2, cyclin B1, and securin degradation and sister chromatid separation. Therefore, in conclusion, we used okadaic acid, dn-PP2Ac-L199P, and FTY720 on mouse eggs to demonstrate that PP2A is needed to for both continued metaphase arrest and successful exit from meiosis.Mouse eggs, as with most vertebrates, arrest at metaphase of the second meiotic division (metII) 3 until fertilized (1-3). Crucial to this arrest is inhibition of the anaphase-promoting complex/cyclosome (APC/C), thereby preventing cyclin B1 and securin degradation and so maintaining high CDK1 kinase (also known as Maturation Promoting Factor, MPF; CDK1/cyclin B1) and low separase (ESPL1) protease activities, respectively (1, 4 -6). At fertilization, a sperm-derived Ca 2ϩ signal causes loss of the APC/C inhibitor Emi2, resulting in a drop in CDK1 activity by cyclin B1 degradation and associated anaphase, driven by the protease separase (7-10).For successful exit from metaphase in either mitosis or meiosis, it is now becoming clear that phosphatase activity is needed to dephosphorylate CDK1 substrates. In Xenopus eggs, calcineurin activity is essential in the process of exit from metII arrest, but this function is not conserved in mouse eggs (11-13). Mammalian eggs may deviate or differ from Xenopus, so it is not always possible to extrapolate across species with accuracy, and indeed this lack of conservation is observed in more than one aspect of cell cycle control (13-15). Instead, the exit of the mouse egg from metII arrest may more closely match mitotic exit in somatic cells and so rely on phosphatase activity from a member of the protein phosphatase 2A (PP2A) family (16 -20).The heterotrimeric nature of the PP2A holoenzyme, coupled with a...

show abstract

Section: Discussionsupporting

confidence: 56%

“…It also interferes with chromosome condensation in maturing oocytes (25). In metII mouse eggs, OA induces spindle lengthening (26) and has been reported to block meiotic exit (27). However, it is clear that mouse oocytes contain PP1 in addition to PP2A, and some of the effects of OA on prophase I mouse oocytes may be due to PP1 inhibition (28,29).…”

Section: B1mentioning

confidence: 99%

Essential Role of Protein Phosphatase 2A in Metaphase II Arrest and Activation of Mouse Eggs Shown by Okadaic Acid, Dominant Negative Protein Phosphatase 2A, and FTY720

Chang¹,

Jennings

Stewart

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Previous results had also shown that inhibition of phosphatases using okadaic acid results in the formation of long microtubules. In starfish (Picard et al ., 1991), mouse oocytes (de Pennart et al ., 1993) and GH4 rat pituitary cells (Van Dolah and Ramsdell, 1992), spindles were shown to be destroyed and replaced by extremely long microtubule networks. This is consistent with our results but, in some of these previous experiments, it was not possible to know whether a type 1 or 2A phosphatase was inhibited.…”

Section: Discussionmentioning

confidence: 99%

Distinct roles of PP1 and PP2A-like phosphatases in control of microtubule dynamics during mitosis

et al. 1997

View full text Add to dashboard Cite

Assembly of a mitotic spindle requires the accurate regulation of microtubule dynamics which is accomplished, at least in part, by phosphorylation-dephosphorylation reactions. Here we have investigated the role of serine-threonine phosphatases in the control of microtubule dynamics using specific inhibitors in Xenopus egg extracts. Type 2A phosphatases are required to maintain the short steady-state length of microtubules in mitosis by regulating the level of microtubule catastrophes, in part by controlling the the microtubule-destabilizing activity and phosphorylation of Op18/stathmin. Type 1 phosphatases are only required for control of microtubule dynamics during the transitions into and out of mitosis. Thus, although both type 2A and type 1 phosphatases are involved in the regulation of microtubule dynamics, they have distinct, non-overlapping roles.

show abstract

“…Treatment of interphase sea urchin egg extracts with OA induces mitoticlike MT dynamics by eliminating the rescue phase of MT dynamics (23). Incubation of mouse oocytes with OA leads to lengthening of mitotic spindles, disorganization of the metaphase plate, and phosphorylation of proteins associated with MTs (24). These results imply that protein phosphatases are necessary for dephosphorylation of MAPs, resulting in increased MT assembly and stability in vivo.…”

Section: Microtubules (Mt)mentioning

confidence: 97%

Protein Phosphatase 1 Is Targeted to Microtubules by the Microtubule-associated Protein Tau

Liao¹,

Li²,

Brautigan³

et al. 1998

Journal of Biological Chemistry

152

View full text Add to dashboard Cite

Phosphorylation has been implicated in the regulation of microtubule (MT) stability and function by controlling the interactions between MTs and MT-associated proteins. We found previously that protein phosphatase inhibitors selectively break down stable MTs, suggesting that protein phosphatases may be involved in regulating MT stability. To identify the protein phosphatases involved, we examined purified calf brain MTs and found a protein phosphatase activity that copurified with MTs to constant stoichiometry. Western blot analysis and inhibitor profiles demonstrated that the MT-associated phosphatase was a type 1 protein phosphatase (PP1), which we named PP1 MT . Recombinant PP1 catalytic subunit (PP1c) did not bind to MTs, whereas PP1 MT did bind, suggesting the presence of proteins that target PP1 to MTs. By Sepharose CL-6B chromatography, the phosphatase activity of PP1 MT eluted as a large protein complex of ϳ400 kDa. High salt (2 M NaCl) treatment followed by CL-6B chromatography dissociated PP1 MT into PP1c and the MT-targeting subunit(s). The MT-targeting subunit was shown to be the MT-associated protein tau by PP1 blot overlays and other assays. Also, recombinant tau reconstituted the binding of PP1c to MTs. These results identify PP1 as the first tau binding protein and suggest that tau is a novel PP1-targeting subunit.

show abstract

Okadaic Acid Induces Spindle Lengthening and Disrupts the Interaction of Microtubules with the Kinetochores in Metaphase II-Arrested Mouse Oocytes

Cited by 26 publications

References 0 publications

Essential Role of Protein Phosphatase 2A in Metaphase II Arrest and Activation of Mouse Eggs Shown by Okadaic Acid, Dominant Negative Protein Phosphatase 2A, and FTY720

Essential Role of Protein Phosphatase 2A in Metaphase II Arrest and Activation of Mouse Eggs Shown by Okadaic Acid, Dominant Negative Protein Phosphatase 2A, and FTY720

Distinct roles of PP1 and PP2A-like phosphatases in control of microtubule dynamics during mitosis

Protein Phosphatase 1 Is Targeted to Microtubules by the Microtubule-associated Protein Tau

Contact Info

Product

Resources

About