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Sensing of 'danger signals' and pathogen-associated molecular patterns defines binary signaling pathways 'upstream'

Laure El Chamy1, Vincent Leclerc, Isabelle Caldelari

  • 1Institut de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique Unité Propre de Recherche 9022, Université Louis Pasteur, Strasbourg Cedex, France.

Nature Immunology
|August 30, 2008
PubMed

Insights

Pattern-recognition receptors in Drosophila detect fungi and bacteria via protease cascades. The study identifies the Grass protease as key to this immune response, involving Persephone in sensing danger signals.

Area of Science:

  • Innate immunity
  • Molecular biology
  • Biochemistry

Background:

  • Pattern-recognition receptors (PRRs) in Drosophila detect microbial components.
  • PRRs activate serine-protease cascades that cleave Spätzle, initiating the Toll pathway.
  • Previous research indicated fungal detection involved specific proteases.

Purpose of the Study:

  • To identify the protease cascade responsible for detecting fungi and Gram-positive bacteria.
  • To elucidate the role of Persephone in microbial sensing.
  • To understand the activation mechanism of Toll receptor ligand Spätzle.

Main Methods:

  • Genetic analysis in Drosophila.
  • Biochemical assays to study protease activity.
  • Investigation of immune response pathways.

Main Results:

  • The protease Grass was identified as a common cascade element for detecting fungi and Gram-positive bacteria via PRRs.
  • Persephone, previously linked to fungal detection, is also crucial for sensing bacterial proteases.
  • Persephone mediates a proteolytic cascade activated by abnormal proteolytic activities, termed 'danger signals'.

Conclusions:

  • Grass protease defines a conserved immune activation pathway for fungal and bacterial detection.
  • Persephone plays a dual role in innate immunity, responding to both fungal and bacterial danger signals.
  • The findings reveal a parallel proteolytic cascade activated by 'danger signals' in Drosophila immunity.

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