Kinetics of Early T Cell Receptor Signaling Regulate the Pathway of Lytic Granule Delivery to the Secretory Domain

Beal, Allison M.; Anikeeva, Nadia; Varma, Rajat; Cameron, Thomas O.; Vasiliver-Shamis, Gaia; Norris, Philip J.; Dustin, Michael L.; Sykulev, Yuri

doi:10.1016/j.immuni.2009.09.004

Cited by 117 publications

(190 citation statements)

References 44 publications

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“…In addition, long lasting NK cell/target cell couples did not lead to target cell lysis, thus further diminishing killing at the population level. Here sustained strong and stable interface actin accumulation could impede the myosin-dependent transport of cytolytic granules through the actin cortex (31) or translocation of granules from the periphery of the interface to its center (32). As an important future challenge, signaling events that downregulate the initially strong polarization in efficient cytolysis need to be identified.…”

Section: Discussionmentioning

confidence: 99%

Transience in polarization of cytolytic effectors is required for efficient killing and controlled by Cdc42

Sinai¹,

Nguyen²,

Schatzle³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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Cytolytic effectors polarize toward target cells for effective killing and IFN-γ secretion. The spatiotemporal features of this polarization and their importance for cytolysis have not been resolved. In cytotoxic T cells and natural killer (NK) cells, transient polarization was consistently associated with effective killing. Polarization was regulated by Cdc42, a small Rho family GTPase universally critical for cytoskeletal dynamics. Transient accumulation of active Cdc42 at the cytolytic effector/target cell interface and focus of such accumulation on the interface center were closely related to cytolysis. Surprisingly, however, the intensity of Cdc42 activation was not. We interfered with Cdc42 activation in NK cells such that sustained polarization in long lasting nonkilling cell couples was selectively blocked. Thus the proportion of the NK cell population displaying transient polarization was increased. As a consequence, cytolytic responder frequency and IFN-γ production were enhanced upon such interference with Cdc42 activation. These data support the notion that transience in polarization is critical for cytolytic effector function, likely by preventing cytolytic effectors from becoming trapped in nonproductive target cell interactions. Each can also secrete IFN-γ to modulate adaptive immune function. To acquire effector capability, cytolytic effectors need to be primed. CTL priming occurs as the consequence of naive CD8 T cell interactions with antigen-presenting dendritic cells. NK cell priming requires cytokines generated predominantly by dendritic cells. However, the nature of the cytokines involved is less certain. IL-12 and IL-18 enable NK cells to secrete IFN-γ (1, 2) and are synergistic (3). IL-15 can promote NK cell expansion (4, 5). IL-15 needs transpresentation by the IL-15 receptor α chain (6, 7), which is induced on dendritic cells by engagement of Toll-like receptors (7). High concentrations of IL-2 effectively prime NK cells in vitro, as often used in clinical settings (8, 9). However, in vivo, IL-2 is dispensable for NK cell priming (5). To understand the role of the polarization of cytolytic effector in their function, the effect of priming conditions on NK cell polarization needs to be taken into account.Target cell contact triggers the complex polarization of primed cytolytic effectors, recruitment of cytolytic granules to the interface (10, 11), cytoskeletal reorientation (12, 13), and receptor clustering (14,15). Cytolytic effector polarization is likely functionally important, as key regulators of cytoskeletal dynamics, Vav and WASP, play critical roles (16-19). However, WASP and Vav are complex molecules with functions that may or may not require cytoskeletal regulation (20,21). The Rho family GTPases Rac and Cdc42 are the central regulators of cytoskeletal dynamics in many cell types (22). Although it has been established that Rac is required for cell coupling and polarization of cytolytic granules (16), the role Cdc42 has not been addressed. Despite the established importance of ...

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Section: Discussionmentioning

confidence: 99%

Transience in polarization of cytolytic effectors is required for efficient killing and controlled by Cdc42

Sinai¹,

Nguyen²,

Schatzle³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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“…There is currently substantial excitement in elucidating the molecular mechanisms of LG polarization to the secretory domain of the CTL-target contact zone (4,24). Jenkins et al (25) have shown that the strength of the TCR signal is exceptionally important for LG accumulation at the IS, and Beal et al (26) unmasked the kinetics of a short and long path of LG to the synapse.…”

mentioning

confidence: 99%

Docking of Lytic Granules at the Immunological Synapse in Human CTL Requires Vti1b-Dependent Pairing with CD3 Endosomes

Pattu

Junker

et al. 2011

The Journal of Immunology

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Lytic granule (LG)-mediated apoptosis is the main mechanism by which CTL kill virus-infected and tumorigenic target cells. CTL form a tight junction with the target cells, which is called the immunological synapse (IS). To avoid unwanted killing of neighboring cells, exocytosis of lytic granules (LG) is tightly controlled and restricted to the IS. In this study, we show that in activated human primary CD8+ T cells, docking of LG at the IS requires tethering LG with CD3-containing endosomes (CD3-endo). Combining total internal reflection fluorescence microscopy and fast deconvolution microscopy (both in living cells) with confocal microscopy (in fixed cells), we found that LG and CD3-endo tether and are cotransported to the IS. Paired but not single LG are accumulated at the IS. The dwell time of LG at the IS is substantially enhanced by tethering with CD3-endo, resulting in a preferential release of paired LG over single LG. The SNARE protein Vti1b is required for tethering of LG and CD3-endo. Downregulation of Vti1b reduces tethering of LG with CD3-endo. This leads to an impaired accumulation and docking of LG at the IS and a reduction of target cell killing. Therefore, Vti1b-dependent tethering of LG and CD3-endo determines accumulation, docking, and efficient lytic granule secretion at the IS.

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“…The SNARE Synaptobrevin 2 facilitates the fusion of lytic granules with the plasma membrane of human CTLs [62]. The strength of the TCR signal controls the focal point for granule exocytosis, permitting release at the pSMAC if the signal is weak instead of delivery to the secretory domain at the cSMAC [63]. Upon centrosomal relocalization, lytics granules are delivered to the IS by a complex formed by kinesin-1/Rab27a/Slp3 [64], suggesting lytic granules depend on microtubules.…”

Section: Late Endosomes: the Multivesicular Bodiesmentioning

confidence: 99%

Immune synapse: conductor of orchestrated organelle movement

Martín-Cófreces¹,

Baixauli²,

Sánchez-Madrid³

2014

Trends in Cell Biology

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SummaryTo ensure proper cell function, intracellular organelles are not randomly distributed within the cell, but polarized and highly constrained by the cytoskeleton and associated adaptor proteins. This relationship between distribution and function was originally found in neurons and epithelial cells; however, recent evidence suggests that it is a more general phenomenon that occurs in many highly specialized cells including the immune T cells. Recent studies reveal that the orchestrated redistribution of organelles is dependent on antigen specific activation and immune-synapse formation of T cells. This review highlights the functional implications of organelle polarization in early T cell activation and examines recent findings on how the immune synapse sets the rhythm of organelle motion and the spread of the activation signal to the nucleus. KeywordsImmune synapse; microcluster; signalosome; mitochondria; vesicle; microtubule Overview of the immune synapseT cell activation starts with an initial wave of signalling that depends on the activation of surface receptors, but subsequent propagation of the signal appears to depend on intracellular compartments, in a sequence driven by the actin and tubulin cytoskeletons [1]. The study of neural synapses highlighted the importance of cell polarity and the specific localization of organelles and clusters of receptors at the pre-and post-synaptic terminals. Despite its transient nature, recent evidence shows that the immune synapse (IS) shares these same neuronal features.The IS is the interface between a T lymphocyte and an antigen presenting cell (APC). During the formation and stabilization of the IS, membrane microdomains and the cytoskeleton reorganize and promote the segregation of membrane and intracellular signaling proteins within the T cell, such as the T cell receptor (TCR), integrins, tyrosine Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts kinases and scaffold proteins such as Linker for activation of T cells (LAT) (Figure 1 and Glossary). The TCR and associated molecules (TCR signalosomes) form microclusters that move to congregate in the central area (central supramolecular activation cluster; cSMAC) of the IS, whereas adhesion receptors such as integrins reorganize in a surrounding external ring called the peripheral or pSMAC ( Figure 2) [2]. In addition, phosphorylation and dephosphorylation, protein-protein interactions and degradation of important molecules such as the TCR-accompanying CD3 complex, tyrosine kinases, phosphatases and adaptor molecules also control receptor activation [3,4]. The polarization of several organelles occurs during T cell stimulation with important roles, such as the centrosome, Golgi apparatus, mitochondria, endoplasmic reticulum and the multivesicular bodies (MVB) [5][6][7][8][9][10]. These rearrangements at the IS promote the activation of signaling pathways that propagate to the nucleus. Signals activating nuclear transcription factors in combination with polarity proteins, such as partit...

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Kinetics of Early T Cell Receptor Signaling Regulate the Pathway of Lytic Granule Delivery to the Secretory Domain

Cited by 117 publications

References 44 publications

Transience in polarization of cytolytic effectors is required for efficient killing and controlled by Cdc42

Transience in polarization of cytolytic effectors is required for efficient killing and controlled by Cdc42

Docking of Lytic Granules at the Immunological Synapse in Human CTL Requires Vti1b-Dependent Pairing with CD3 Endosomes

Immune synapse: conductor of orchestrated organelle movement

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