Role of Nonhistone Protein Phosphorylation in the Regulation of Mitosis in Mammalian Cells

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

doi:10.1007/978-1-4612-5178-1_4

Cited by 3 publications

(1 citation statement)

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“…Moreover, the GI factors can be activated in Go cells or Colcemid-arrested mitotic cells by UV irradiation. The Gt cell extracts, upon incubation with mitotic cell extracts, inactivate maturation-promoting activity (MPA; Adlakha et al, 1983Adlakha et al, , 1984a, induce dephosphorylation of mitotic nonhistone proteins (Adlakha et al, 1984b) and mitosis-specific phosphoprotein antigens (Adlakha et al, 1985a), and specifically decrease the activity of the mitosis-specific kinases (Halleck et al, 1984b). Several other groups have recently described similar factors at the end of meiosis that inactivate MPF (Gerhart et al, 1984;Lohka and Mailer, 1985;Miake-Lye and Kirschner, 1985;Newport, 1987).…”

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Amphibian oocyte maturation induced by extracts of Physarum polycephalum in mitosis.

Adlakha

Shipley

Zhao

et al. 1988

The Journal of Cell Biology

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Abstract. The orderly progression of eukaryotic cells from interphase to mitosis requires the close coordination of various nuclear and cytoplasmic events. Studies from our laboratory and others on animal cells indicate that two activities, one present mainly in mitotic cells and the other exclusively in G~-phase cells, play a pivotal role in the regulation of initiation and completion of mitosis, respectively. The purpose of this study was to investigate whether these activities are expressed in the slime mold Physarum polycephalum in which all the nuclei traverse the cell cycle in natural synchrony. Extracts were prepared from plasmodia in various phases of the cell cycle and tested for their ability to induce germinal vesicle breakdown and chromosome condensation after microinjection into Xenopus laevis oocytes. We found that extract of cells at 10-20 min before metaphase consistently induced germinal vesicle breakdown in oocytes. Preliminary characterization, including purification on a DNA-cellulose affinity column, indicated that the mitotic factors from Physarum were functionally very similar to HeLa mitotic factors. We also identified a number of mitosis-specific antigens in extracts from Physarum plasmodia, similar to those of HeLa cells, using the mitosis-specific monoclonal antibodies MPM-2 and MPM-7. Interestingly, we also observed an activity in Physarum at 45 min after metaphase (i.e., in early S phase since it has no Gt) that is usually present in HeLa cells only during the GI phase of the cell cycle. These are the first studies to show that maturationpromoting factor activity is present in Physarum during mitosis and is replaced by the G1 factor (or antimaturation-promoting factor) activity in a postmitotic stage. A comparative study of these factors in this slime mold and in mammalian cells would be extremely valuable in further understanding their function in the regulation of eukaryotic cell cycle and their evolutionary relationship to one another.URING the interphase-to-mitosis transition, various dramatic changes occur in the eukaryotic cell. The major changes include the condensation of chromatin into discrete chromosomes, breakdown of the nuclear membrane, disassembly of the cytoskeletal arrays, and formarion of the mitotic spindle (Adlakha et al., 1985a;Baserga, 1976Baserga, , 1981Karsenti et al., 1984;Mazia, 1974;Pardee et al., 1978;Prescott, 1976). Beginning with telophase, these processes are driven in the opposite direction until the initiation of DNA synthesis. The nuclear envelope re-forms and chromosomes begin to decondense. The chromatin reaches its most decondensed state by the end of the Gm period when it becomes accessible for DNA replication. After replication of chromosomes, the whole process of major macromolecular reorganization of the nucleus associated with mitosis restarts. Although the mechanisms for the control of these events are not well understood, several lines of evidence suggest that there are factors (proteins) present in cells during mitosis and meiosis that ar...

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