Long noncoding RNA HITT coordinates with RGS2 to inhibit PD-L1 translation in T cell immunity
Qingyu Lin, … , Hao Liu, Ying Hu
Qingyu Lin, … , Hao Liu, Ying Hu
Published April 4, 2023
Citation Information: J Clin Invest. 2023;133(11):e162951. https://doi.org/10.1172/JCI162951.
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Research Article Immunology Oncology

Long noncoding RNA HITT coordinates with RGS2 to inhibit PD-L1 translation in T cell immunity

Abstract

Programmed cell death ligand 1 (PD-L1) is an immune checkpoint protein frequently expressed in human cancers that contributes to immune evasion through its binding to PD-1 on activated T cells. Unveiling the mechanisms underlying PD-L1 expression is essential for understanding the impact of the immunosuppressive microenvironment and is also crucial for the purpose of reboosting antitumor immunity. However, how PD-L1 is regulated, particularly at translational levels, remains largely unknown. Here, we discovered that a long noncoding RNA (lncRNA), HIF-1α inhibitor at translation level (HITT), was transactivated by E2F transcription factor 1 (E2F1) under IFN-γ stimulation. It coordinated with regulator of G protein signaling 2 (RGS2) in binding to the 5′ UTR of PD-L1, resulting in reduced PD-L1 translation. HITT expression enhanced T cell–mediated cytotoxicity both in vitro and in vivo in a PD-L1–dependent manner. The clinical correlation between HITT/PD-L1 and RGS2/PD-L1 expression was also detected in breast cancer tissues. Together, these findings demonstrate the role of HITT in antitumor T cell immunity, highlighting activation of HITT as a potential therapeutic strategy for enhancing cancer immunotherapy.

Authors

Qingyu Lin, Tong Liu, Xingwen Wang, Guixue Hou, Zhiyuan Xiang, Wenxin Zhang, Shanliang Zheng, Dong Zhao, Qibin Leng, Xiaoshi Zhang, Minqiao Lu, Tianqi Guan, Hao Liu, Ying Hu

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Figure 6

HITT forms RNA-RNA duplex with PD-L1–5′-UTR.

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HITT forms RNA-RNA duplex with PD-L1–5′-UTR. (A) PD-L1–5′-UTR levels det...
(A) PD-L1–5′-UTR levels determined by qRT-PCR following CLIP RGS2 under IFN-γ treatment with or without HITT KD, with GAPDH mRNA and CLIP IgG as negative controls. (B) Schematic showing in vitro RNA-RNA binding assay to detect the binding between in vitro–synthesized unlabeled HITT and biotin–PD-L1–5′-UTR. (C) HITT and HITT fragments pulled down by biotin–PD-L1–5′-UTR, biotin-PD-L1–5′-UTR fragments, or biotin–antisense–PD-L1–5′-UTR control determined by qRT-PCR with or without RNase H, RNase A, or RNase III. (D) FISH showing colocalization between HITT and PD–L1–5′-UTR in PBS or IFN-γ–treated HeLa cells. (E) Schematic showing complementary sequence (BSs) between HITT and PD-L1–5′-UTR according to the prediction of an online bioinformatic tool (http://rna.informatik.uni-freiburg.de/IntaRNA/Input.jsp). Three PD-L1–5′-UTR mutations, which lost the complementarity site of PD-L1–5′-UTR at BS1 (BS1-MT), BS2 (BS2-MT), and both BS1 and BS2 (BS1+2-MT) were generated and are shown in the diagram. (F) HITT coprecipitated by biotin–PD-L1–5′-UTR (WT or mutants) or biotin–antisense–PD-L1–5′-UTR control determined by qRT-PCR. (G) GST-tagged RGS2 pulled down by biotin-HITT and biotin-antisense-HITT control in the presence of unlabeled FL PD-L1–5′-UTR or PD-L1–5′-UTR mutants determined by WB in an in vitro RNA pull-down assay. Data derived from 3 independent experiments are presented as mean ± SEM. ****P < 0.0001; NS, not significant by 1-way ANOVA (A, C, and F). Scale bars: 20 μm (left 3 panels); 5 μm (right 2 panels).