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An allosteric site in the T-cell receptor C? domain plays a critical signalling role.

ABSTRACT: The molecular mechanism through which the interaction of a clonotypic ?? T-cell receptor (TCR) with a peptide-loaded major histocompatibility complex (p/MHC) leads to T-cell activation is not yet fully understood. Here we exploit a high-affinity TCR (B4.2.3) to examine the structural changes that accompany binding to its p/MHC ligand (P18-I10/H2-Dd). In addition to conformational changes in complementarity-determining regions (CDRs) of the TCR seen in comparison of unliganded and bound X-ray structures, NMR characterization of the TCR ?-chain dynamics reveals significant chemical shift effects in sites removed from the MHC-binding site. Remodelling of electrostatic interactions near the C? H3 helix at the membrane-proximal face of the TCR, a region implicated in interactions with the CD3 co-receptor, suggests a possible role for an allosteric mechanism in TCR signalling. The contribution of these TCR residues to signal transduction is supported by mutagenesis and T-cell functional assays.

SUBMITTER: Natarajan K

PROVIDER: S-EPMC5440810 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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An allosteric site in the T-cell receptor Cβ domain plays a critical signalling role.

Natarajan Kannan K McShan Andrew C AC Jiang Jiansheng J Kumirov Vlad K VK Wang Rui R Zhao Huaying H Schuck Peter P Tilahun Mulualem E ME Boyd Lisa F LF Ying Jinfa J Bax Ad A Margulies David H DH Sgourakis Nikolaos G NG

Nature communications 20170516

The molecular mechanism through which the interaction of a clonotypic αβ T-cell receptor (TCR) with a peptide-loaded major histocompatibility complex (p/MHC) leads to T-cell activation is not yet fully understood. Here we exploit a high-affinity TCR (B4.2.3) to examine the structural changes that accompany binding to its p/MHC ligand (P18-I10/H2-D<sup>d</sup>). In addition to conformational changes in complementarity-determining regions (CDRs) of the TCR seen in comparison of unliganded and boun ...[more]

PMID: 28508865

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Project description:BACKGROUND:Idiopathic pulmonary fibrosis (IPF) is a devastating disease with a median survival of only three to 5?years. Fibroblast proliferation is a hallmark of IPF as is secretion of extracellular matrix proteins from fibroblasts. However, it is still uncertain how IPF fibroblasts acquire the ability to progressively proliferate. Periostin is a matricellular protein highly expressed in the lung tissues of IPF patients, playing a critical role in the pathogenesis of pulmonary fibrosis. However, it remains undetermined whether periostin affects lung fibroblast proliferation. METHODS:In this study, we first aimed at identifying periostin-dependently expressed genes in lung fibroblasts using DNA microarrays. We then examined whether expression of cyclins and CDKs controlling cell cycle progression occur in a periostin-dependent manner. We next examined whether downregulation of cell proliferation-promoting genes by knockdown of periostin or integrin, a periostin receptor, using siRNA, is reflected in the cell proliferation of lung fibroblasts. We then looked at whether lung fibroblasts derived from IPF patients also require periostin for maximum proliferation. We finally investigated whether CP4715, a potent inhibitor against integrin ?V?3 (a periostin receptor), which we have recently found blocks TGF-? signaling, followed by reduced BLM-induced pulmonary fibrosis in mice, can block proliferation of lung fibroblasts derived from IPF patients. RESULTS:Many cell-cycle-related genes are involved in the upregulated or downregulated genes by periostin knockdown. We confirmed that in lung fibroblasts, periostin silencing downregulates expression of several cell-cycle-related molecules, including the cyclin, CDK, and, E2F families, as well as transcription factors such as B-MYB and FOXM1. Periostin or integrin silencing slowed proliferation of lung fibroblasts and periostin silencing increased the distribution of the G0/G1 phase, whereas the distribution of the G2/M phase was decreased. Lung fibroblasts derived from IPF patients also required periostin for maximum proliferation. Moreover, CP4715 downregulated proliferation along with expression of cell-cycle-related genes in IPF lung fibroblasts as well as in normal lung fibroblasts. CONCLUSIONS:Periostin plays a critical role in the proliferation of lung fibroblasts and the present results provide us a solid basis for considering inhibitors of the periostin/integrin ?V?3 interaction for the treatment of IPF patients.

Dataset Information

An allosteric site in the T-cell receptor C? domain plays a critical signalling role.

Publications

An allosteric site in the T-cell receptor Cβ domain plays a critical signalling role.

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