Rogers Jhordan, Ma Rong, Hu Yuesong, Salaita Khalid
Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia, 30322, USA.
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, 30332, USA.
bioRxiv. 2023 Aug 8:2023.08.07.552310. doi: 10.1101/2023.08.07.552310.
The surface of T cells is studded with T cell receptors (TCRs) that are used to scan target cells to identify peptide-major histocompatibility complexes (pMHCs) signatures of viral infection or cancerous mutation. It is now established that the TCR-pMHC complex is highly transient and experiences mechanical forces that augment the fidelity of T cell activation. An important question in this area pertains to the role of force duration in immune activation. Herein, we report the development of force probes that autonomously terminate tension within a time window following mechanical triggering. Force-induced site-specific enzymatic cleavage (FUSE) probes tune tension duration by controlling the rate of a force-triggered endonuclease hydrolysis reaction. This new capability provides a method to study how accumulated force duration contributes to T cell activation. We screened DNA sequences and identified FUSE probes that disrupt mechanical interactions with >7.1 piconewtons (pN) between TCRs and pMHCs. Force lifetimes (τ) are tunable from tens of min down to 1.9 min. T cells challenged with FUSE probes presenting cognate antigens with τ of 1.9 min demonstrated dampened markers of early activation, thus demonstrating that repeated mechanical sampling boosts TCR activation. Repeated mechanical sampling >7.1 pN was found to be particularly critical at lower pMHC antigen densities, wherein the T cell activation declined by 23% with τ of 1.9 min. FUSE probes with >17.0 pN response showed weaker influence on T cell triggering further showing that TCR-pMHC with >17.0 pN are less frequent compared to >7.1 pN. Taken together, FUSE probes allow a new strategy to investigate the role of force dynamics in mechanotransduction broadly and specifically suggest a model of serial mechanical engagement in antigen recognition.
T细胞表面布满了T细胞受体（TCR），这些受体用于扫描靶细胞，以识别病毒感染或癌变突变的肽-主要组织相容性复合体（pMHC）特征。现已证实，TCR-pMHC复合体高度短暂，并经历增强T细胞激活保真度的机械力。该领域的一个重要问题涉及力持续时间在免疫激活中的作用。在此，我们报告了力探针的开发，这些探针在机械触发后的时间窗口内自动终止张力。力诱导的位点特异性酶切（FUSE）探针通过控制力触发的核酸内切酶水解反应速率来调节张力持续时间。这种新能力提供了一种方法，用于研究累积的力持续时间如何促进T细胞激活。我们筛选了DNA序列，并鉴定出能破坏TCR与pMHC之间大于7.1皮牛顿（pN）机械相互作用的FUSE探针。力寿命（τ）可从数十分钟调节至1.9分钟。用τ为1.9分钟的FUSE探针呈递同源抗原刺激的T细胞，其早期激活标志物受到抑制，从而表明重复的机械采样可增强TCR激活。发现在较低的pMHC抗原密度下，大于7.1 pN的重复机械采样尤为关键，其中当τ为1.9分钟时，T细胞激活下降了23%。响应大于17.0 pN的FUSE探针对T细胞触发的影响较弱，进一步表明与大于7.1 pN相比，大于17.0 pN的TCR-pMHC较少见。综上所述，FUSE探针提供了一种新策略，可广泛研究力动力学在机械转导中的作用，并具体提出了抗原识别中的系列机械参与模型。
