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J Cell Sci. 2018 Nov 21;131(22). pii: jcs218883. doi: 10.1242/jcs.218883.

The topology of the lymphotoxin β receptor that accumulates upon endolysosomal dysfunction dictates the NF-κB signaling outcome.

Author information

1
Laboratory of Cell Biology, International Institute of Molecular and Cell Biology, 02-109, Warsaw, Poland.
2
Department of Molecular Neuropharmacology, Institute of Pharmacology Polish Academy of Sciences, 31-343, Krakow, Poland.
3
Department of Biochemistry, University of Geneva, 1211, Geneva, Switzerland.
4
Laboratory of Cell Biology, International Institute of Molecular and Cell Biology, 02-109, Warsaw, Poland miaczynska@iimcb.gov.pl.

Abstract

Cytokine receptors, such as tumor necrosis factor receptor I (TNFRI, also known as TNFRSF1A) and lymphotoxin β receptor (LTβR), activate inflammatory nuclear factor (NF)-κB signaling upon stimulation. We have previously demonstrated that depletion of ESCRT components leads to endosomal accumulation of TNFRI and LTβR, and their ligand-independent signaling to NF-κB. Here, we studied whether other perturbations of the endolysosomal system could trigger intracellular accumulation and signaling of ligand-free LTβR. While depletion of the CORVET components had no effect, knockdown of Rab7a or HOPS components, or pharmacological inhibition of lysosomal degradation, caused endosomal accumulation of LTβR and increased its interaction with the TRAF2 and TRAF3 signaling adaptors. However, the NF-κB pathway was not activated under these conditions. We found that knockdown of Rab7a or HOPS components led to sequestration of LTβR in intraluminal vesicles of endosomes, thus precluding NF-κB signaling. This was in contrast to the LTβR localization on the outer endosomal membrane that was seen after ESCRT depletion and was permissive for signaling. We propose that the inflammatory response induced by intracellular accumulation of endocytosed cytokine receptors critically depends on the precise receptor topology within endosomal compartments.

KEYWORDS:

Endocytosis; Endosome; HOPS complex; NF-κB signaling; Rab7

PMID:
30333141
DOI:
10.1242/jcs.218883

Conflict of interest statement

Competing interestsThe authors declare no competing or financial interests.

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