InsP3R-SEC5 interaction on phagosomes modulates innate immunity to Candida albicans by promoting cytosolic Ca2+ elevation and TBK1 activity

Long Yang, Wenwen Gu, King Ho Cheung, Lan Yan, Benjamin Chun Kit Tong, Yuanying Jiang*, Jun Yang*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

4 Citations (Scopus)
6 Downloads (Pure)


Background: Candida albicans (C. albicans) invasion triggers antifungal innate immunity, and the elevation of cytoplasmic Ca2+ levels via the inositol 1,4,5-trisphosphate receptor (InsP3R) plays a critical role in this process. However, the molecular pathways linking the InsP3R-mediated increase in Ca2+ and immune responses remain elusive. 

Results: In the present study, we find that during C. albicans phagocytosis in macrophages, exocyst complex component 2 (SEC5) promotes InsP3R channel activity by binding to its C-terminal α-helix (H1), increasing cytosolic Ca2+ concentrations ([Ca2+]c). Immunofluorescence reveals enriched InsP3R-SEC5 complex formation on phagosomes, while disruption of the InsP3R-SEC5 interaction by recombinant H1 peptides attenuates the InsP3R-mediated Ca2+ elevation, leading to impaired phagocytosis. Furthermore, we show that C. albicans infection promotes the recruitment of Tank-binding kinase 1 (TBK1) by the InsP3R-SEC5 interacting complex, leading to the activation of TBK1. Subsequently, activated TBK1 phosphorylates interferon regulatory factor 3 (IRF-3) and mediates type I interferon responses, suggesting that the InsP3R-SEC5 interaction may regulate antifungal innate immune responses not only by elevating cytoplasmic Ca2+ but also by activating the TBK1-IRF-3 pathway. 

Conclusions: Our data have revealed an important role of the InsP3R-SEC5 interaction in innate immune responses against C. albicans.

Original languageEnglish
Article number46
JournalBMC Biology
Publication statusPublished - 27 Apr 2018

Scopus Subject Areas

  • Biotechnology
  • Structural Biology
  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • Plant Science
  • Developmental Biology
  • Cell Biology

User-Defined Keywords

  • Antifungal innate immune response
  • Exocyst complex component 2 (SEC5)
  • Inositol 1,4,5-trisphosphate receptors (InsP3R)
  • Tank-binding kinase 1 (TBK1)


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