Scientific article
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Sec22b regulates phagosome maturation by promoting ORP8-mediated lipid exchange at endoplasmic reticulum-phagosome contact sites

Published inCommunications biology, vol. 6, no. 1, 1008
Publication date2023-10-04
First online date2023-10-04
Abstract

Phagosome maturation is critical for immune defense, defining whether ingested material is destroyed or converted into antigens. Sec22b regulates phagosome maturation, yet how has remained unclear. Here we show Sec22b tethers endoplasmic reticulum-phagosome membrane contact sites (MCS) independently of the known tether STIM1. Sec22b knockdown increases calcium signaling, phagolysosome fusion and antigen degradation and alters phagosomal phospholipids PI(3)P, PS and PI(4)P. Levels of PI(4)P, a lysosome docking lipid, are rescued by Sec22b re-expression and by expression of the artificial tether MAPPER but not the MCS-disrupting mutant Sec22b-P33. Moreover, Sec22b co-precipitates with the PS/PI(4)P exchange protein ORP8. Wild-type, but not mutant ORP8 rescues phagosomal PI(4)P and reduces antigen degradation. Sec22b, MAPPER and ORP8 but not P33 or mutant-ORP8 restores phagolysosome fusion in knockdown cells. These findings clarify an alternative mechanism through which Sec22b controls phagosome maturation and beg a reassessment of the relative contribution of Sec22b-mediated fusion versus tethering to phagosome biology.

Keywords
  • ER
  • ER-to-Golgi intermediate compartment
  • ERGIC
  • ERS24
  • Osbpl5
  • Osbpl8
  • Phosphoinositide
  • Phosphatidylinositol
Citation (ISO format)
CRIADO SANTOS, Nina et al. Sec22b regulates phagosome maturation by promoting ORP8-mediated lipid exchange at endoplasmic reticulum-phagosome contact sites. In: Communications biology, 2023, vol. 6, n° 1, p. 1008. doi: 10.1038/s42003-023-05382-0
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Identifiers
Additional URL for this publicationhttps://www.nature.com/articles/s42003-023-05382-0
Journal ISSN2399-3642
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Creation10/05/2023 8:12:37 AM
First validation10/09/2023 6:54:37 AM
Update time10/09/2023 6:54:37 AM
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