Cytotoxic Granule Exocytosis From Human Cytotoxic T Lymphocytes Is Mediated by VAMP7

Abstract

Cytotoxic T lymphocytes kill infected or malignant cells through the directed release of cytotoxic substances at the site of target cell contact, the immunological synapse. While genetic association studies of genes predisposing to early-onset life-threatening hemophagocytic lymphohistiocytosis has identified components of the plasma membrane fusion machinery, the identity of the vesicular components remain enigmatic. Here, we identify VAMP7 as an essential component of the vesicular fusion machinery of primary, human T cells. VAMP7 co-localizes with granule markers throughout all stages of T cell maturation and simultaneously fuses with granule markers at the IS. Knock-down of VAMP7 expression significantly decreased the killing efficiency of T cells, without diminishing early T cell receptor signaling. VAMP7 exerts its function in a SNARE complex with Syntaxin11 and SNAP-23 on the plasma membrane. The identification of the minimal fusion machinery in T cells provides a starting point for the development of potential drugs in immunotherapy.

Alpha synuclein in hematopoiesis and immunity

“…Additionally, based on structural characteristics and previous studies, syntaxin-11 and SNAP-23 are predicted to be the t-SNARE proteins mediating the fusion step of lytic granule release [116]. This appears to be the case since VAMP7, syntaxin-11, and SNAP-23 have been identified in human cytotoxic T cells as facilitators of lytic granule exocytosis [117].…”

Various Stages of Immune Synapse Formation Are Differently Dependent on the Strength of the TCR Stimulus

“…CD3-mTFP was described previously [38]. pHuji was amplified from a previously described VAMP7 pHuji construct [39] using the forward primer 5 ATG TAT ACC CAA GCT TAT GGT GAG CAA GGG CGA G 3 to add HindIII site and the reverse primer 3 ATG TAT ACG CGG ATC CTT ACT TGT ACA GCT CGT C 5 to add the BamHI site. The PCR product was digested and ligated into an optimized pMax-vector containing Synaptobrevin2 as previously described [40].…”

“…The TIRFM setup used was described previously [39] with the following changes: a 445 nm laser (100 mW) along with a 561 nm solid state laser (100 mW) were used for excitation along with a filter cube consisting of an emission filter ZET 442/514/568 and a dichroic beamsplitter ZT405/440/514/561 (Chroma Technology Corp, Olching, Germany). The pixel size of the camera was 160 nm.…”

Higher Incidence of B Cell Malignancies in Primary Immunodeficiencies: A Combination of Intrinsic Genomic Instability and Exocytosis Defects at the Immunological Synapse

“…The interaction between VAMP8 and syntaxin 4 is required for the fusion of these recycling endosomes with the plasma membrane ( 233 , 234 ) ( Figure 8 ). Upon fusion, syntaxin 11 is transferred to the plasma membrane and can interact with VAMP7 that is present on arriving cytotoxic granules ( 235 ) ( Figure 8 ). Alterations in VAMP7, VAMP8, and syntaxin 4 can lead to impaired degranulation and killing.…”