Adhesion to laminin-1 and collagen IV induces the formation of Ca ²⁺ microdomains that sensitize mouse T cells for activation

Abstract

During an immune response, T cells migrate from blood vessel walls into inflamed tissues by migrating across the endothelium and through extracellular matrix (ECM). Integrins facilitate T cell binding to endothelial cells and ECM proteins. Here, we report that Ca 2+ microdomains observed in the absence of T cell receptor (TCR)/CD3 stimulation are initial signaling events triggered by adhesion to ECM proteins that increase the sensitivity of primary murine T cells to activation. Adhesion to the ECM proteins collagen IV and laminin-1 increased the number of Ca 2+ microdomains in a manner dependent on the kinase FAK, phospholipase C (PLC), and all three inositol 1,4,5-trisphosphate receptor (IP 3 R) subtypes and promoted the nuclear translocation of the transcription factor NFAT-1. Mathematical modeling predicted that the formation of adhesion-dependent Ca 2+ microdomains required the concerted activity of two to six IP 3 Rs and ORAI1 channels to achieve the increase in the Ca 2+ concentration in the ER–plasma membrane junction that was observed experimentally and that required SOCE. Further, adhesion-dependent Ca 2+ microdomains were important for the magnitude of the TCR-induced activation of T cells on collagen IV as assessed by the global Ca 2+ response and NFAT-1 nuclear translocation. Thus, adhesion to collagen IV and laminin-1 sensitizes T cells through a mechanism involving the formation of Ca 2+ microdomains, and blocking this low-level sensitization decreases T cell activation upon TCR engagement.

Time-resolved role of P2X4 and P2X7 during CD8+ T cell activation

“…Spots were marked by pixel-based segmentation using the trainable weka (Waikato Environment for Knowledge Analysis) segmentation plugin on Fiji (version 1.53f). The area (sum of detected spots) of all NFAT-1 spots in the nucleus and cytoplasm was calculated using a MATLAB (version R2018b) script ( 8 ). To distinguish between the nucleus and the cytoplasm DAPI staining was used.…”

“…This promotes the activation of stromal interaction molecules 1 and 2 (STIM1/2) and thus store-operated Ca 2+ entry (SOCE) through ORAI1 channels ( 7 ), leading to an amplification of initial Ca 2+ microdomains ( 6 ). Sustained Ca 2+ microdomains result in the translocation of nuclear factor of activated T cells (NFAT) ( 8 ), which promotes the secretion of pro-inflammatory cytokines such as interleukin-17 (IL-17) ( 9 ) or interferon-γ (IFN-γ) ( 10 ). Interfering with the Ca 2+ signaling cascade has potential therapeutic effects.…”

10th European Calcium Society symposium: The Ca2+-signaling toolkit in cell function, health and disease

“…The establishment of these microdomains depend on the binding of laminin-1 or collagen IV to integrins via FAK/PLC activity and through IP 3 Rs. This process facilitates Ca 2+ entry through STIM-Orai1 coupling with subsequent translocation of the transcription factor NFAT-1 to the nucleus ( Weiß et al, 2023 ).…”

T cell Ca2+ microdomains through the lens of computational modeling

“…Hereafter, ADCM and TDCM will refer to the spatially restricted and short-lived Ca 2+ increases occurring in the so-called microdomains. TDMC are amplified by SOCE ( 27 ) ( Figure 1B ) and purinergic signaling via P2X4 and P2X7 ( 28 ).…”