Key Points
CytVs tether with lysosomes in T cells.
Lysosome-tethered CytVs are preferentially transported to their desired destination.
Lysosome tethering can mediate directionally distinctive CytV transport.
Abstract
Delivery of vesicles to their desired destinations plays a central role in maintaining proper cell functionality. In certain scenarios, depending on loaded cargos, the vesicles have spatially distinct destinations. For example, in T cells, some cytokines (e.g., IL-2) are polarized to the T cell–target cell interface, whereas the other cytokines are delivered multidirectionally (e.g., TNF-α). In this study, we show that in primary human CD4+ T cells, both TNF-α+ and IL-2+ vesicles can tether with endocytic organelles (lysosomes/late endosomes) by forming membrane contact sites. Tethered cytokine-containing vesicle (CytV)–endocytic organelle pairs are released sequentially. Only endocytic organelle-tethered CytVs are preferentially transported to their desired destination. Mathematical models suggest that endocytic organelle tethering could regulate the direction of cytokine transport by selectively attaching different microtubule motor proteins (such as kinesin and dynein) to the corresponding CytVs. These findings establish the previously unknown interorganelle tethering to endocytic organelles as a universal solution for directional cytokine transport in CD4+ T cells. Modulating tethering to endocytic organelles can, therefore, coordinately control directionally distinct cytokine transport.
Footnotes
This work was funded by the Deutsche Forschungsgemeinschaft (Projects SFB1027 A2 [to B.Q.], SFB1027 A3 [to H.R.], and SFB1027 C3 [to V.H.]) and by the Leibniz Association (INM Fellow to B.Q.). P.N.-H. is supported by the Novartis Foundation (Grant 17B078), the Prof. Dr. Max Cloëtta Foundation 2019 Medical Researcher Award, and the Swiss National Science Foundation (Grant 310030_189094).
The online version of this article contains supplemental material.
Abbreviations used in this article:
- CLEM
- correlative light and electron microscopy
- co-IP
- coimmunoprecipitation
- CytV
- cytokine-containing vesicle
- dist
- distal area
- EM
- electron microscopy
- ER
- endoplasmic reticulum
- F
- forward
- IS
- immunological synapse
- LCSM
- laser confocal scanning microscopy
- LG
- lytic granule
- MCS
- membrane contact site
- MTOC
- microtubule organizing center
- N.A.
- numerical aperture
- PDB
- Protein Data Bank
- R
- reverse
- SIM
- structured illumination microscopy
- siRNA
- small interfering RNA
- SNARE
- soluble NSF attachment protein receptor
- TIRF
- total internal reflection fluorescence
- WT
- wild-type.
- Received February 20, 2020.
- Accepted September 20, 2020.
- Copyright © 2020 by The American Association of Immunologists, Inc.
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