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PGRP-SD, an Extracellular Pattern-Recognition Receptor, Enhances Peptidoglycan-Mediated Activation of the Drosophila

Igor Iatsenko1, Shu Kondo2, Dominique Mengin-Lecreulx3

  • 1Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland.

Immunity
|November 17, 2016
PubMed

Insights

Drosophila PGRP-SD acts as an extracellular receptor, enhancing the innate immune response to bacteria by improving peptidoglycan detection and signaling. This discovery highlights dual intra- and extracellular receptor use in bacteria detection.

Area of Science:

  • Immunology
  • Microbiology
  • Genetics

Background:

  • Metazoan innate immunity relies on pattern-recognition receptors to detect microbes.
  • In Drosophila, Gram-negative bacteria are recognized by PGRP-LC and PGRP-LE receptors.

Purpose of the Study:

  • To investigate the role of PGRP-SD in Drosophila's innate immune response.
  • To elucidate the mechanism by which PGRP-SD interacts with other immune receptors and bacterial components.

Main Methods:

  • Mutagenesis studies of PGRP-SD.
  • Analysis of Imd signaling pathway activation.
  • Assays for bacterial susceptibility and peptidoglycan localization.

Main Results:

  • PGRP-SD functions upstream of PGRP-LC as an extracellular receptor.
  • PGRP-SD enhances peptidoglycan-mediated Imd signaling activation.
  • PGRP-SD mutants show impaired immunity and increased susceptibility to specific bacteria.
  • PGRP-SD promotes peptidoglycan localization to the cell surface.
  • PGRP-SD antagonizes PGRP-LB, a negative regulator, to fine-tune immune response.

Conclusions:

  • Drosophila PGRP-SD acts as an extracellular receptor, analogous to mammalian CD14.
  • The study reveals a dual receptor system (intra- and extracellular) for bacterial detection in Drosophila.
  • PGRP-SD plays a crucial role in modulating the intensity and effectiveness of the innate immune response.

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