Evidence for the presence of inhibitors of mitotic factors during G1 period in mammalian cells.

Adlakha, Ramesh C.; Sahasrabuddhe, Chintaman G.; Wright, David; Rao, Potu N.

doi:10.1083/jcb.97.6.1707

Cited by 66 publications

(23 citation statements)

References 40 publications

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“…Thus we can expect that the S-phase cytoplasm prevents the reappearance of MPF in fused cells, similar to the situations described by Adlakha et al (1983) and Balakier & Masui (1986). Thus we can expect that the S-phase cytoplasm prevents the reappearance of MPF in fused cells, similar to the situations described by Adlakha et al (1983) and Balakier & Masui (1986).…”

Section: Discussionsupporting

confidence: 69%

Response of avian nuclei to mammalian maturation promoting factor (MPF)

Trefil

Horská

Kaňka

et al. 1995

Zygote

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Chicken blastodermal cells (stage X) were fused to mouse enucleated oocytes with either no or high maturation promoting factor (MPF) activity. High MPF levels always induced premature chromosome condensation (PCC) irrespective of the number of nuclei fused to a single oocyte. When a single blastodermal cell was fused to a single oocyte without MPF activity the nucleus remained intact for up to 3 h and thereafter underwent PCC. A quite different situation was observed after multiple fusion of several blastodermal cells to a single oocyte without MPF activity. Here, the transplanted nuclei remained intact even after prolonged culture but underwent extensive swelling. DNA synthesis was detected in almost all unfused blastodermal cells. However, after the fusion of several blastodermal cells to a single oocyte no DNA synthesis could be detected. These results provide further evidence that MPF is the universal cell-cycle regulator in the animal kingdom. Its activity is blocked (or neutralised) after fusion to several S-phase cells. Interestingly, our results further suggest that DNA synthesis is suppressed in meiotic cytoplasm even in the presence of an intact nuclear envelope.

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Section: Discussionsupporting

confidence: 69%

Response of avian nuclei to mammalian maturation promoting factor (MPF)

Trefil

Horská

Kaňka

et al. 1995

Zygote

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“…A similar mechanism of periodic destruction near the end of each mitosis has been shown to operate in the mitosis-inducing cyclin A protein of clam embryos (27) as well as the cyclin proteins of sea urchin embryos (28). In mammalian cells, the degradation of mitotic factors after the completion of mitosis is supported by early cell fusion studies (2) and by microinjection experiments with extracts from various stages ofthe cell cycle to induce oocyte maturation (29,30). These findings suggest that protein degradation is also important in mitotic control.…”

Section: Discussionmentioning

confidence: 80%

Periodic mitotic events induced in the absence of DNA replication.

Schlegel

Pardee

1987

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

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We have discovered and report here a means of separating a mitotic "subcycle" from the Gj-and S-phase events of the mammalian cell cycle. Time-lapse videomicroscopy of Syrian hamster fibroblast (BHK) cells revealed that caffeine could induce multiple entries into mitosis while cells were blocked in DNA synthesis. As with normal mitoses, the abundance of mitosis-specific phosphoproteins was coupled with the condensation of chromatin. The BHK temperaturesensitive mutant tsBN2 also completed multiple entries into mitosis while arrested during DNA replication and raised to the restrictive temperature. Periodic mitotic events occurred even when BHK cells were exposed to low concentrations of serum or cycloheximide, conditions that prevent the cycling of BHK cells by blocking their entry into S phase. These results suggest that an oscillation governing the activation and inactivation of mitotic factors can be generated in mammalian cells and uncoupled from the G, and DNA replication events of the normal cell cycle. This system will be useful for examining the molecular nature of mitotic factors.The mammalian cell cycle is classically viewed as an interdependent sequence of biochemical events. The completion of DNA replication has therefore been considered a prerequisite for the initiation of mitosis (1). This view was supported by the studies of Rao and Johnson (2), which showed that mitosis was delayed in G2-phase cells that were fused with S-phase cells. Both nuclei underwent mitosis simultaneously, but only after the S-phase nucleus had completed DNA replication. Two examples of alterations in the temporal sequence of cell cycle events have been reported in mammalian cells. Chromosome condensation, nuclear envelope breakdown, and other mitotic events occur at the restrictive temperature in the BHK temperature-sensitive mutant tsBN2 (3) and in normal BHK cells that have been arrested in S phase and exposed to caffeine (4, 5). These studies showed that one final mitosis can be uncoupled from the completion of DNA replication. Both exposure to caffeine and suppression of DNA replication are required for this premature induction of mitosis in normal BHK cells (4). Experiments with inhibitors suggest that these conditions permit the accumulation of mitosis-inducing mRNA(s) and their protein(s) (5). The present report extends these observations by providing evidence that mitotic events can be made to occur periodically, independent of Gj-and S-phase events. We propose that an oscillator controlling the entry into and exit from mitosis can be uncoupled from the normal cell cycle and examine its regulation during growth-inhibiting conditions. MATERIALS AND METHODSCell Culture and Synchronization. Syrian Hamster fibroblast (BHK) cells were grown and synchronized in early S phase as described (4). Briefly, cells were plated at 1 X 105 cells per 60-mm dish and grown at 370C in Dulbecco's modified Eagle's medium (DMEM) with 10% fetal calf serum for 24 hr. Synchrony in early S phase was achieved by incubation in isoleuc...

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“…Since the mitotic index of granula cells is < 1%, fully grown mammalian oocytes are supplied with &dquo;interphase factors&dquo; described in somatic cells (Rao & Adlakha, 1985). These interphase-specific substances might be a negative signal passing from granulosa cells to the oocyte and preventing activation of maturation-promoting factor (MPF) (Adlakha et al, 1983;Fulka Jr. et al, 1985). The …”

Section: Introductionmentioning

confidence: 99%

RNA and protein synthesis requirements for the resumption of meiosis in rabbit oocytes : the role of cumulus cells

Motlı́k

Fulka²,

Procházka³

et al. 1989

Reprod. Nutr. Dévelop.

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Summary ― In vitro maturation of rabbit cumulus-enclosed oocytes was fully inhibited in aamanitin-(100 8 g/ml) and cycloheximide-(5 pg/ml) supplemented media.The inhibition was reversible and substantially reduced by delaying the addition of a-amanitin (2h) or cycloheximide (3 h).In contrast, both drugs did not inhibit germinal vesicle breakdown in denuded oocytes.Co-culture of granulosa cells (1 x 10 6 /ml) with denuded oocytes did not substitute for an intact cumulus.The data presented here suggest that the resumption of meiosis in rabbit cumulus-enclosed oocytes is dependent upon early transcriptional and translational events which probably occur within the cumulus cells.oocyte maturation -cumulus oophorus ― transcription -translation -rabbit Résumé ― Synthèse d'ARN et de protéines nécessaires à la reprise de la méiose : rôle des cellules du cumulus oophorus. La reprise de la méiose in vitro d'ovocytes de lapins inclus dans leur cumulus oophorus est complètement inhibée par l'a-amanitine (100 pg/ml) et le cycloheximide (5 pglmo. L'inhibition est réversible et fortement diminuée si l'on retarde le traitement par l'aamanitine (2 h) ou la cycloheximide (3 h).Au contraire, les deux inhibiteurs n'empêchent pas la rupture de la vésicule germinale d'ovocytes dénudés (sans cumulus oophorus).Des cellules de la granulosa (f0!lml) en coculture avec des ovocytes dénudés ne remplacent pas un cumulus oophorus intact. Les résultats présentés suggèrent que la reprise de la méiose dans des ovocytes de lapins inclus dans le cumulus oophorus est sous la dépendance de phénomènes de transcription et de traduction survenant probablement dans les cellules périovocytaires. maturation de l'ovocyte -cumulus oophorus ― transcription -traduction -lapin

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Evidence for the presence of inhibitors of mitotic factors during G1 period in mammalian cells.

Cited by 66 publications

References 40 publications

Response of avian nuclei to mammalian maturation promoting factor (MPF)

Response of avian nuclei to mammalian maturation promoting factor (MPF)

Periodic mitotic events induced in the absence of DNA replication.

RNA and protein synthesis requirements for the resumption of meiosis in rabbit oocytes : the role of cumulus cells

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