Atypical TNF-TNFR superfamily binding interface in the GITR-GITRL complex for Tcell activation.

Min Zhao,Jianxun Qi,Le Kang,Lijun Fu,Yan Chai,George F Gao,Yan Li,Shuguang Tan,Meng Sun,Bin Zeng,Shuo Wang

doi:10.1016/j.celrep.2021.109734

Min Zhao, Jianxun Qi + Show 9 more

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https://doi.org/10.1016/j.celrep.2021.109734

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Journal: Cell reports	Publication Date: Sep 1, 2021
Citations: 3	License type: cc-by

Abstract

Glucocorticoid-induced tumor necrosis factor receptor family-related protein (GITR) is a critical regulatory molecule in modulation of Tcell immune responses. Here we report the mouse GITR (mGITR) and mGITR ligand (mGITRL) complex structure and find that the binding interface of mGITR and mGITRL is distinct from the typical tumor necrosis factor superfamily (TNFSF)/TNF receptor superfamily (TNFRSF) members. mGITR binds to its ligand with a single domain, whereas the binding interface on mGITRL is located on the side, which is distal from conserved binding sites of TNFSF molecules. Mutational analysis reveals that the binding interface of GITR/GITRL in humans is conserved with that in the mouse. Substitution of key interacting D93-I94-V95 (DIV) in mGITR with the corresponding K93-F94-S95 (KFS) in human GITR enables cross-recognition with human GITRL and cross-activation of receptor signaling. The findings of this study substantially expand our understanding of the interaction of TNFSF/TNFRSF superfamily molecules and can benefit the future design of biologics by targeting GITR/GITRL.

Highlights

Glucocorticoid-induced tumor necrosis factor receptor familyrelated protein (GITR), a type I transmembrane protein characterized by three cysteine-rich domain (CRD) pseudorepeats in its extracellular domain, was first identified as a member of the tumor necrosis factor receptor superfamily (TNFRSF) in 1997 (Nocentini et al, 1997)
All three mutants display similar binding affinity with mouse GITR (mGITR) as wild-type mGITR ligand (mGITRL). These findings suggest that mGITRL may interact with mGITR in a non-canonical manner that is distinct from the typical tumor necrosis factor superfamily (TNFSF) and TNFRSF interface
Monomeric and dimeric mGITR proteins could be obtained, and formation of mGITR dimers was mediated by disulfide bonds, as analyzed by reducing and non-reducing SDS-PAGE (Figure S1A). mGITRL proteins exhibited dimeric oligomerization by analytical sedimentation, which is consistent with previous studies (Figures S1B and S1C; Zhou et al, 2008)

Summary

Introduction

Glucocorticoid-induced tumor necrosis factor receptor familyrelated protein (GITR), a type I transmembrane protein characterized by three cysteine-rich domain (CRD) pseudorepeats in its extracellular domain, was first identified as a member of the tumor necrosis factor receptor superfamily (TNFRSF) in 1997 (Nocentini et al, 1997). Targeting GITR with agonistic monoclonal antibodies (mAbs) or GITRL to activate immune responses has been investigated for treatment of tumors and autoimmune diseases (Calmels et al, 2005; Leyland et al, 2017; Lu et al, 2014; Mitsui et al, 2010; Petrillo et al, 2015; Sukumar et al, 2017; Tigue et al, 2017). Activating GITR signaling with agonists or GITRL can reverse the suppression reactivity of Treg cells and promote proliferation of effector CD8+ T cells and CD4+ Th9 cells, which results in upregulated cytokine production and, thereafter, tumor regression (Coe et al, 2010; Kim et al, 2015; Leyland et al, 2017; Sukumar et al, 2017; Tigue et al, 2017). GITR can costimulate group 2 innate lymphoid cells (ILC2s) and, could serve as a drug target for ILC2-mediated allergic and inflammatory diseases (Galle-Treger et al, 2019; Nagashima et al, 2018)

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