Loss of ARPC1B impairs cytotoxic T lymphocyte maintenance and cytolytic activity
Lyra O. Randzavola, … , Taco W. Kuijpers, Gillian M. Griffiths
Lyra O. Randzavola, … , Taco W. Kuijpers, Gillian M. Griffiths
Published December 2, 2019; First published November 11, 2019
Citation Information: J Clin Invest. 2019;129(12):5600-5614. https://doi.org/10.1172/JCI129388.
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Research Article Cell biology Immunology

Loss of ARPC1B impairs cytotoxic T lymphocyte maintenance and cytolytic activity

Abstract

CD8 cytotoxic T lymphocytes (CTLs) rely on rapid reorganization of the branched F-actin network to drive the polarized secretion of lytic granules, initiating target cell death during the adaptive immune response. Branched F-actin is generated by the nucleation factor actin-related protein 2/3 (Arp2/3) complex. Patients with mutations in the actin-related protein complex 1B (ARPC1B) subunit of Arp2/3 show combined immunodeficiency, with symptoms of immune dysregulation, including recurrent viral infections and reduced CD8+ T cell count. Here, we show that loss of ARPC1B led to loss of CTL cytotoxicity, with the defect arising at 2 different levels. First, ARPC1B is required for lamellipodia formation, cell migration, and actin reorganization across the immune synapse. Second, we found that ARPC1B is indispensable for the maintenance of TCR, CD8, and GLUT1 membrane proteins at the plasma membrane of CTLs, as recycling via the retromer and WASH complexes was impaired in the absence of ARPC1B. Loss of TCR, CD8, and GLUT1 gave rise to defects in T cell signaling and proliferation upon antigen stimulation of ARPC1B-deficient CTLs, leading to a progressive loss of CD8+ T cells. This triggered an activation-induced immunodeficiency of CTL activity in ARPC1B-deficient patients, which could explain the susceptibility to severe and prolonged viral infections.

Authors

Lyra O. Randzavola, Katharina Strege, Marie Juzans, Yukako Asano, Jane C. Stinchcombe, Christian M. Gawden-Bone, Matthew N.J. Seaman, Taco W. Kuijpers, Gillian M. Griffiths

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Figure 3

Arp2/3 inhibition impairs actin dynamics in CTLs.

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Arp2/3 inhibition impairs actin dynamics in CTLs. (A) Confocal projectio...
(A) Confocal projections of OT-I CTLs treated with 90 μM of CK689 or CK666 mixed with OVA-loaded EL4 for 25 minutes; cells were fixed and labeled with antibodies against CD8 (green), actin (red), and γ-tubulin (white) to mark the centrosome (white arrows). A representative 3D reconstruction of en face interaction (white box) of the actin phenotype at the interface between the OT-I CTLs and its target. Scale bars: 5 μm. (B) Quantitation derived from images as exemplified in A and showing the percentages of conjugates displaying the different actin reorganization phenotypes at the synapse (left panel, see Supplemental Figure 1) or the centrosome distance relative to the synapse (right panel: CK689 CTLs = 190, conjugates = 91, CK666 CTLs = 179, conjugates = 80, mean of 3 independent experiments, error bars indicate SEM). (C) Actin dynamics and centrosome position (white arrows) in OT-I CTLs expressing EGFP-Lifeact (green) and PACT-mRFP (red) during interaction with EL4 blue at various time point (min:s) from the first contact. Images are confocal projections from Supplemental Videos 1 and 2. Scale bars: 5 μm. (D) OT-I CTL motility while migrating on ICAM-1 following treatment with 90 μM CK666 or CK689. The speeds of cell migration were analyzed with time-lapse images (see Methods). The graph includes plots of 28 cells for CK689 and 18 cells for CK666 from 3 videos each. ***P < 0.0001, unpaired t test.