Program in Molecular Medicine
Cell Biology | Developmental Biology
IFT20, a component of the intraflagellar transport (IFT) system that controls ciliogenesis, regulates immune synapse assembly in the non-ciliated T-cell by promoting T-cell receptor (TCR) recycling. Here, we have addressed the role of Rab8 (for which there are two isoforms Rab8a and Rab8b), a small GTPase implicated in ciliogenesis, in TCR traffic to the immune synapse. We show that Rab8, which colocalizes with IFT20 in Rab11(+) endosomes, is required for TCR recycling. Interestingly, as opposed to in IFT20-deficient T-cells, TCR(+) endosomes polarized normally beneath the immune synapse membrane in the presence of dominant-negative Rab8, but were unable to undergo the final docking or fusion step. This could be accounted for by the inability of the vesicular (v)-SNARE VAMP-3 to cluster at the immune synapse in the absence of functional Rab8, which is responsible for its recruitment. Of note, and similar to in T-cells, VAMP-3 interacts with Rab8 at the base of the cilium in NIH-3T3 cells, where it regulates ciliary growth and targeting of the protein smoothened. The results identify Rab8 as a new player in vesicular traffic to the immune synapse and provide insight into the pathways co-opted by different cell types for immune synapse assembly and ciliogenesis.
Immune synapse, Rab8, TCR recycling
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DOI of Published Version
J Cell Sci. 2015 Jul 15;128(14):2541-52. doi: 10.1242/jcs.171652. Epub 2015 Jun 1. Link to article on publisher's site
Journal of cell science
Finetti, Francesca; Patrussi, Laura; Galgano, Donatella; Cassioli, Chiara; Perinetti, Giuseppe; Pazour, Gregory J.; and Baldari, Cosima T., "The small GTPase Rab8 interacts with VAMP-3 to regulate the delivery of recycling T-cell receptors to the immune synapse" (2015). Open Access Articles. 2692.