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Nuclei and microtubule asters stimulate maturation/M phase promoting factor (Mpf) activation in Xenopus eggs and egg cytoplasmic extracts

journal contribution
posted on 2023-06-07, 21:09 authored by Daniel Pérez-Mongiovi, Clare Beckhelling, Patrick Chang, Christopher C Ford, Evelyn Houliston
Although maturation/M phase promoting factor (MPF) can activate autonomously in Xenopus egg cytoplasm, indirect evidence suggests that nuclei and centrosomes may focus activation within the cell. We have dissected the contribution of these structures to MPF activation in fertilized eggs and in egg fragments containing different combinations of nuclei, centrosomes, and microtubules by following the behavior of Cdc2 (the kinase component of MPF), the regulatory subunit cyclin B, and the activating phosphatase Cdc25. The absence of the entire nucleus–centrosome complex resulted in a marked delay in MPF activation, whereas the absence of the centrosome alone caused a lesser delay. Nocodazole treatment to depolymerize microtubules through first interphase had an effect equivalent to removing the centrosome. Furthermore, microinjection of isolated centrosomes into anucleate eggs promoted MPF activation and advanced the onset of surface contraction waves, which are close indicators of MPF activation and could be triggered by ectopic MPF injection. Finally, we were able to demonstrate stimulation of MPF activation by the nucleus–centriole complex in vitro, as low concentrations of isolated sperm nuclei advanced MPF activation in cycling cytoplasmic extracts. Together these results indicate that nuclei and microtubule asters can independently stimulate MPF activation and that they cooperate to enhance activation locally.

History

Publication status

  • Published

Journal

Journal of Cell Biology

ISSN

0021-9525

Publisher

The Rockefeller University Press

Issue

5

Volume

150

Page range

963-974

ISBN

0021-9525

Department affiliated with

  • Biology and Environmental Science Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

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