HVEM structures and mutants reveal distinct functions of binding to LIGHT and BTLA/CD160.

Weifeng Liu,Ting-Fang Chou,Qingyang Wang,Scott J Garforth,Steven C Almo,Goo-Young Seo,Sarah C Garrett-Thomson,Mitchell Kronenberg,Jeffrey B Bonanno,Udupi A Ramagopal,Kiyokazu Kakugawa,Hilde Cheroutre,Elena Fedorov,Kenneth Kim

doi:10.1084/jem.20211112

Abstract

HVEM is a TNF (tumor necrosis factor) receptor contributing to a broad range of immune functions involving diverse cell types. It interacts with a TNF ligand, LIGHT, and immunoglobulin (Ig) superfamily members BTLA and CD160. Assessing the functional impact of HVEM binding to specific ligands in different settings has been complicated by the multiple interactions of HVEM and HVEM binding partners. To dissect the molecular basis for multiple functions, we determined crystal structures that reveal the distinct HVEM surfaces that engage LIGHT or BTLA/CD160, including the human HVEM-LIGHT-CD160 ternary complex, with HVEM interacting simultaneously with both binding partners. Based on these structures, we generated mouse HVEM mutants that selectively recognized either the TNF or Ig ligands in vitro. Knockin mice expressing these muteins maintain expression of all the proteins in the HVEM network, yet they demonstrate selective functions for LIGHT in the clearance of bacteria in the intestine and for the Ig ligands in the amelioration of liver inflammation.

Highlights

Members of the TNF receptor (TNFR) superfamily (TNFRSF) regulate diverse processes, but in several cases, understanding these processes is hampered by the ability of receptors and ligands to bind to multiple partners (Bossen et al, 2006)
Results human HVEM (hHVEM)–hLIGHT complex exists as a 3:3 assembly The extracellular domains of human LIGHT and hHVEM (∼15 kD) were purified to homogeneous, monodisperse species as indicated by analytical size exclusion chromatography (SEC; Fig. 1 A)
The crystal structure of the hHVEM–hLIGHT complex was determined to the resolution of 2.30 Aby molecular replacement using Protein Data Bank (PDB) entries 4KG8 and 4FHQ as starting search models (Table 1)

Summary

Introduction

Members of the TNF receptor (TNFR) superfamily (TNFRSF) regulate diverse processes, but in several cases, understanding these processes is hampered by the ability of receptors and ligands to bind to multiple partners (Bossen et al, 2006). A TNF superfamily (TNFSF) ligand for HVEM was characterized, known as LIGHT (homologous to lymphotoxin, exhibits inducible expression and competes with HSV glycoprotein D for binding to herpesvirus entry mediator, a receptor expressed on T lymphocytes) or TNFSF14 (Harrop et al, 1998a; Harrop et al, 1998b). In T lymphocytes, it stimulates proliferation, cytokine production, and the development of CD8 T cell memory (Desai et al, 2017; Harrop et al, 1998a; Harrop et al, 1998b; Tamada et al, 2000). LIGHT engages HVEM to stimulate cytokine production by type 3 innate lymphoid cells (ILC3s; Seo et al, 2018), and in keratinocytes, it binds HVEM to stimulate periostin, contributing to atopic dermatitis (Herro et al, 2018)

Methods

Results

Conclusion