Actin behavior in bulk cytoplasm is cell cycle regulated in early vertebrate embryos

Christine M. Field, Martin Wühr, Graham A. Anderson, Hao Yuan Kueh, Devin Strickland, Timothy J. Mitchison

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

The mechanical properties of cells change as they proceed through the cell cycle, primarily owing to regulation of actin and myosin II. Most models for cell mechanics focus on actomyosin in the cortex and ignore possible roles in bulk cytoplasm. We explored cell cycle regulation of bulk cytoplasmic actomyosin in Xenopus egg extracts, which is almost undiluted cytoplasm from unfertilized eggs. We observed dramatic gelation-contraction of actomyosin in mitotic (M phase) extract where Cdk1 activity is high, but not in interphase (I-phase) extract. In spread droplets, M-phase extract exhibited regular, periodic pulses of gelation-contraction a few minutes apart that continued for many minutes. Comparing actin nucleation, disassembly and myosin II activity between M-phase and I-phase extracts, we conclude that regulation of nucleation is likely to be the most important for cell cycle regulation. We then imaged F-actin in early zebrafish blastomeres using a GFP-Utrophin probe. Polymerization in bulk cytoplasm around vesicles increased dramatically during mitosis, consistent with enhanced nucleation. We conclude that F-actin polymerization in bulk cytoplasm is cell cycle regulated in early vertebrate embryos and discuss possible biological functions of this regulation.

Original languageEnglish (US)
Pages (from-to)2086-2095
Number of pages10
JournalDevelopment
Volume138
Issue number13
DOIs
StatePublished - Jul 1 2011

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Developmental Biology

Keywords

  • Actin
  • Actomyosin
  • Cell cycle
  • Embryo

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    Field, C. M., Wühr, M., Anderson, G. A., Kueh, H. Y., Strickland, D., & Mitchison, T. J. (2011). Actin behavior in bulk cytoplasm is cell cycle regulated in early vertebrate embryos. Development, 138(13), 2086-2095. https://doi.org/10.1242/jcs.082263