Hyd ubiquitinates the NF-κB co-factor Akirin to operate an effective immune response in Drosophila

PLoS Pathog. 2020 Apr 27;16(4):e1008458. doi: 10.1371/journal.ppat.1008458. eCollection 2020 Apr.


The Immune Deficiency (IMD) pathway in Drosophila melanogaster is activated upon microbial challenge with Gram-negative bacteria to trigger the innate immune response. In order to decipher this nuclear factor κB (NF-κB) signaling pathway, we undertook an in vitro RNAi screen targeting E3 ubiquitin ligases specifically and identified the HECT-type E3 ubiquitin ligase Hyperplastic discs (Hyd) as a new actor in the IMD pathway. Hyd mediated Lys63 (K63)-linked polyubiquitination of the NF-κB cofactor Akirin was required for efficient binding of Akirin to the NF-κB transcription factor Relish. We showed that this Hyd-dependent interaction was required for the transcription of immunity-related genes that are activated by both Relish and Akirin but was dispensable for the transcription of genes that depend solely on Relish. Therefore Hyd is key in NF-κB transcriptional selectivity downstream of the IMD pathway. Drosophila depleted of Akirin or Hyd failed to express the full set of genes encoding immune-induced anti-microbial peptides and succumbed to immune challenges. We showed further that UBR5, the mammalian homolog of Hyd, was also required downstream of the NF-κB pathway for the activation of Interleukin 6 (IL6) transcription by LPS or IL-1β in cultured human cells. Our findings link the action of an E3 ubiquitin ligase to the activation of immune effector genes, deepening our understanding of the involvement of ubiquitination in inflammation and identifying a potential target for the control of inflammatory diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Drosophila
  • Drosophila Proteins / genetics
  • Drosophila Proteins / immunology*
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / immunology*
  • Drosophila melanogaster / microbiology
  • Gram-Negative Bacteria / physiology
  • HeLa Cells
  • Humans
  • Immunity, Innate
  • Nuclear Proteins / genetics
  • Nuclear Proteins / immunology*
  • Transcription Factors / genetics
  • Transcription Factors / immunology*
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / immunology*
  • Ubiquitination


  • Drosophila Proteins
  • Nuclear Proteins
  • Rel protein, Drosophila
  • Transcription Factors
  • akirin protein, Drosophila
  • hyd protein, Drosophila
  • Ubiquitin-Protein Ligases

Grants and funding

This work was supported by the Centre National de la Recherche Scientifique (http://www.cnrs.fr/fr/page-daccueil) in the frame of the LIA «REL2 and resistance to malaria». This work was performed under the framework of the LABEX: ANR-10- LABX-0036_NETRNA and ANR-17-EURE-0023, through a funding of the state managed by the French National Research Agency (https://anr.fr/) as part of the Investments for the future program and also from a European Research Council (https://erc.europa.eu/) Advanced Grant (AdG_20090506 ‘‘Immudroso,’’ to J.-M.R.). Generation of RNAi reagents by M.B. was supported by DFG DRiC (https://www.dfg.de/). N.M. is a Fellow at the University of Strasbourg Institute for Advanced Study (USIAS-2018-073; http://www.usias.fr/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.