Cytotoxic T lymphocyte effector function is independent of nucleus–centrosome dissociation

Winnie W Y Lui‐Roberts,Alex T Ritter,Anna Akhmanova,Jane C Stinchcombe,Gillian M Griffiths,Iakowos Karakesisoglou

doi:10.1002/eji.201242525

Winnie W Y Lui‐Roberts, Alex T Ritter + Show 4 more

Open Access

https://doi.org/10.1002/eji.201242525

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Abstract

Cytotoxic T lymphocytes (CTLs) kill tumorigenic and virally infected cells by targeted secretion of lytic granule contents. The precise point at which secretion occurs is directed by the centrosome docking at the immunological synapse (IS). The centrosome is highly dynamic in CTLs, lagging behind the nucleus in the uropod of migrating CTLs, but translocating across the entire length of the cell to dock at the IS when a target cell is recognized. While in most cell types, the centrosome is always closely associated with the nuclear membrane, in CTLs, it often appears to be dissociated from the nucleus, both in migrating cells and when forming an IS. We asked whether this dissociation is required for CTL killing, by expressing GFP-BICD2-NT-nesprin-3, which tethers the centrosome to the nucleus irreversibly. Immunofluorescence microscopy revealed that the centrosome polarized successfully to the central supramolecular activation complex (cSMAC) of the synapse in GFP-BICD2-NT-nesprin-3-expressing CTLs, with the centrosome and nucleus migrating together to the IS. CTLs in which the centrosome was “glued” to the nucleus were able to dock and release granules at the IS as effectively as mock-treated cells. These data demonstrate that CTL cytotoxicity is independent of centrosomal dissociation from the nuclear envelope.

Highlights

Cytotoxic T lymphocytes (CTLs) are part of the adaptive immune system
When CTLs are engaged with targets, the centrosome appears at some distance from the nucleus, as revealed by EM and immunofluorescence images of CTLs derived from OT-I TCRtransgenic mice [19] (Fig. 1B and C)
When CTLs are engaged with targets, the detached centrosome is on the anterior side of the nucleus oriented toward the target at the immunological synapse (IS)

Summary

Introduction

Cytotoxic T lymphocytes (CTLs) are part of the adaptive immune system. They express CD8 on their cell surface, and kill virally infected and tumorigenic cells by releasing perforin and granzymes from specialized secretory lysosomes, known as lytic granules.When a CTL recognizes a target, an immunological synapse (IS) is formed at the interface between the two cells. Cytotoxic T lymphocytes (CTLs) are part of the adaptive immune system. They express CD8 on their cell surface, and kill virally infected and tumorigenic cells by releasing perforin and granzymes from specialized secretory lysosomes, known as lytic granules. When a CTL recognizes a target, an immunological synapse (IS) is formed at the interface between the two cells. Secretion occurs at a very precise point in the immune synapse, next to the cSMAC and within the pSMAC. Upon TCRmediated recognition of a target, the centrosome polarizes toward and contacts the plasma membrane adjacent to the cSMAC. The lytic granules move along microtubules and are delivered to the plasma membrane at the point determined by the centrosome [4]

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