School of Life Sciences, Zhengzhou University, Zhengzhou, 450001, China.
School of Pharmaceutical Sciences (Shenzhen), Sun Yat-Sen University, Shenzhen, 518107, China.
Cell Commun Signal. 2021 Feb 8;19(1):12. doi: 10.1186/s12964-020-00701-y.
TIGIT, as a novel immune checkpoint molecule involved in T cell and NK cell anergy, could induce the immune tolerance and escape through binding with its ligand PVR. Blockade of TIGIT/PVR is considered as a promising strategy in cancer immunotherapy. However, to facilitate the design of inhibitors targeting TIGIT/PVR, the structural characteristics and binding mechanism still need to be further studied.
In this study, molecular dynamics (MD) simulations and in silico mutagenesis were used to analyze the interaction between TIGIT and its ligand PVR. Then, PVR mutants were designed and their activities were determined by using TIGIT overexpressed Jurkat cells.
The results suggested that the loops of PVR (CC' loop, C'C″ loop, and FG loop) underwent a large intra-molecular rearrangement, and more hydrogen bond crosslinking between PVR and TIGIT were formed during MD simulations. The potential residues for PVR to interact with TIGIT were identified and utilized to predict high affinity PVR mutants. Through the biological activity evaluation, four PVR mutants (S72W, S72R, G131V and S132Q) with enhanced affinity to TIGIT were discovered, which could elicit more potent inhibitory effects compared with the wild type PVR.
The MD simulations analysis provided new insights into the TIGIT/PVR interaction model, and the identified PVR mutants (S72W, S72R, G131V and S132Q) could serve as new candidates for immunotherapy to block TIGIT/PVR. Video Abstract.
TIGIT 作为一种新型免疫检查点分子，参与 T 细胞和 NK 细胞失能，可通过与配体 PVR 结合诱导免疫耐受和逃逸。阻断 TIGIT/PVR 被认为是癌症免疫治疗的一种有前途的策略。然而，为了促进针对 TIGIT/PVR 的抑制剂的设计，仍需要进一步研究其结构特征和结合机制。
在这项研究中，使用分子动力学（MD）模拟和计算机诱变分析了 TIGIT 与其配体 PVR 之间的相互作用。然后，设计了 PVR 突变体，并通过过表达 TIGIT 的 Jurkat 细胞测定其活性。
结果表明，PVR 的环（CC'环、C'C″环和 FG 环）发生了较大的分子内重排，并且在 MD 模拟过程中 PVR 与 TIGIT 之间形成了更多的氢键交联。确定了 PVR 与 TIGIT 相互作用的潜在残基，并利用这些残基预测了高亲和力的 PVR 突变体。通过生物活性评估，发现了四个与 TIGIT 亲和力增强的 PVR 突变体（S72W、S72R、G131V 和 S132Q），它们比野生型 PVR 能引起更强的抑制作用。
MD 模拟分析为 TIGIT/PVR 相互作用模型提供了新的见解，并且鉴定的 PVR 突变体（S72W、S72R、G131V 和 S132Q）可以作为新的免疫治疗候选物，用于阻断 TIGIT/PVR。
