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Histone H4 mRNA is stored as a small cytoplasmic RNP during the G2 phase in Physarum polycephalum

M L Wilhelm1, B Toublan, R A Fujita

  • 1Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France.

Biochemical and Biophysical Research Communications
|May 31, 1988
PubMed

Insights

Histone H4 gene transcription in Physarum polycephalum peaks during G2 phase. Stored H4 mRNA in the cytoplasm is later translated during the subsequent S phase, ensuring protein availability.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Histone H4 is crucial for DNA packaging and replication.
  • Gene transcription regulation is vital for cell cycle progression.

Purpose of the Study:

  • To investigate the temporal regulation of histone H4 gene transcription in Physarum polycephalum.
  • To understand the storage and activation mechanisms of histone H4 mRNA during the cell cycle.

Main Methods:

  • In vivo pulse-labeling experiments to measure mRNA synthesis rates.
  • Sucrose gradient fractionation of cytoplasmic ribonucleoprotein (RNP) complexes.
  • Blot hybridization for subcellular fraction analysis.

Main Results:

  • Histone H4 gene transcription significantly increases during the G2 phase, peaking at the end of G2.
  • H4 mRNA accumulates in the cytoplasm during G2 but remains untranslated.
  • Stored H4 mRNA is stabilized as an inactive mRNP complex until the S phase.

Conclusions:

  • Histone H4 gene transcription is tightly regulated, occurring primarily during the G2 phase.
  • Physarum polycephalum employs a post-transcriptional regulatory mechanism, storing H4 mRNA for timely protein production during S phase.
  • Cytoplasmic RNP complex formation is key to stabilizing and storing H4 mRNA.

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