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Different modes of translation for hid, grim and sickle mRNAs in Drosophila

P Vazquez-Pianzola1, G Hernández, B Suter

  • 1Max-Planck-Institut für biophysikalische Chemie, Abt. Molekulare Biologie, Am Fassberg 11, Göttingen, Germany.

Cell Death and Differentiation
|June 24, 2006
PubMed

Insights

Internal ribosome entry sites (IRESs) drive translation of Drosophila proapoptotic genes during apoptosis. This IRES-mediated translation bypasses the need for cap-dependent initiation, crucial for cell survival.

Area of Science:

  • Molecular Biology
  • Genetics
  • Developmental Biology

Background:

  • Protein synthesis is typically inhibited during apoptosis.
  • Internal ribosome entry sites (IRESs) enable translation of specific mRNAs even when cap-dependent translation is impaired.

Purpose of the Study:

  • To investigate the role of IRESs in the translation of Drosophila proapoptotic genes.
  • To determine if hid and grim mRNAs utilize IRES-mediated translation.

Main Methods:

  • Utilized cell-free embryonic extracts from Drosophila.
  • Tested uncapped-mRNA reporters with hid and grim 5'UTRs.
  • Assessed translation in the presence of cap competitors and impaired cap-dependent translation systems.
  • Analyzed polysome association of endogenous mRNAs in heat-shocked embryos.

Main Results:

  • The 5'UTRs of hid and grim mRNAs were shown to promote translation of uncapped-mRNA reporters.
  • hid and grim mRNA 5'UTRs were confirmed to drive IRES-mediated translation.
  • Endogenous hid and grim mRNAs were found in polysomes of heat-shocked embryos, indicating cap-independent translation.
  • In contrast, sickle mRNA translation remained cap-dependent.

Conclusions:

  • IRES-dependent initiation plays a significant role in the translation of Drosophila proapoptotic genes.
  • This mechanism suggests novel regulatory pathways for gene expression during apoptosis.

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