CD28 costimulation is organized by signaling condensates and counteracted by PD-1
6 affiliations
- 1State Key Laboratory of Epigenetic Regulation and Intervention, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- 2College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- 3Kidney Disease Center, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, Zhejiang, China
- 4Department of Gastrointestinal Medical Oncology, Harbin Medical University Cancer Hospital, Harbin 150001, Heilongjiang, China
- 5Department of Cardiology of the Second Affiliated Hospital and Department of Cell Biology, Zhejiang University School of Medicine, Liangzhu Laboratory, Zhejiang University, Hangzhou 311121, Zhejiang, China
- 6Zhejiang Laboratory for Systems and Precision Medicine, Zhejiang University Medical Center, Hangzhou 311121, Zhejiang, China
Abstract
T cell activation relies on the coordinated integration of T cell receptor (TCR) and cosignaling pathways, yet how these signals are physically organized remains unclear. Here, we demonstrate that CD28 co-stimulation is driven by a condensation mechanism in which the CD28 intracellular domain (ICD) forms signaling condensates with the Src-family kinase Lck. Ligand engagement promotes CD28 ICD accessibility and triggers rapid CD28/Lck condensation, enhancing CD28 phosphorylation, cytoskeletal polarization, and cytokine production. The downstream effectors of CD28, including PI3K and GRB2, can also be recruited into the CD28-Lck condensates in our reconstituted system. We further identify PD-1 as a graded regulator of this process: Monophosphorylated PD-1 is recruited into CD28/Lck condensates, whereas diphosphorylated PD-1 competitively binds the CD28 ICD and dissolves these assemblies. CD28 and PD-1 ICDs also undergo condensation directly, revealing a dynamic and compositionally heterogeneous signaling system. Guided by this competitive condensation mechanism, we engineer CD28 ICD mutants that preserve Lck condensation while resisting PD-1-mediated disruption. Incorporation of these condensation-selective mutants into Chimeric antigen receptor (CAR) constructs confers resistance to inhibitory signaling and enhances antitumor efficacy in vivo. These findings establish condensation as a central organizing principle of CD28 costimulation and provide a biophysical framework for engineering more resilient therapeutic T cells.
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BibTeX
@article{chen2026cd28,
title = {{CD28 costimulation is organized by signaling condensates and counteracted by PD-1}},
author = {Hui Chen and Songfang Wu and Yong Zhang and Wei Hu and Changjie Lou and Wei Chen and Jizhong Lou},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
year = {2026},
month = oct,
doi = {10.1073/pnas.2612742123},
url = {https://doi.org/10.1073/pnas.2612742123},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - CD28 costimulation is organized by signaling condensates and counteracted by PD-1
AU - Hui Chen
AU - Songfang Wu
AU - Yong Zhang
AU - Wei Hu
AU - Changjie Lou
AU - Wei Chen
AU - Jizhong Lou
PY - 2026
DA - 2026/10/21
JO - Proceedings of the National Academy of Sciences of the United States of America
DO - 10.1073/pnas.2612742123
UR - https://doi.org/10.1073/pnas.2612742123
AB - T cell activation relies on the coordinated integration of T cell receptor (TCR) and cosignaling pathways, yet how these signals are physically organized remains unclear. Here, we demonstrate that CD28 co-stimulation is driven by a condensation mechanism in which the CD28 intracellular domain (ICD) forms signaling condensates with the Src-family kinase Lck. Ligand engagement promotes CD28 ICD accessibility and triggers rapid CD28/Lck condensation, enhancing CD28 phosphorylation, cytoskeletal polarization, and cytokine production. The downstream effectors of CD28, including PI3K and GRB2, can also be recruited into the CD28-Lck condensates in our reconstituted system. We further identify PD-1 as a graded regulator of this process: Monophosphorylated PD-1 is recruited into CD28/Lck condensates, whereas diphosphorylated PD-1 competitively binds the CD28 ICD and dissolves these assemblies. CD28 and PD-1 ICDs also undergo condensation directly, revealing a dynamic and compositionally heterogeneous signaling system. Guided by this competitive condensation mechanism, we engineer CD28 ICD mutants that preserve Lck condensation while resisting PD-1-mediated disruption. Incorporation of these condensation-selective mutants into Chimeric antigen receptor (CAR) constructs confers resistance to inhibitory signaling and enhances antitumor efficacy in vivo. These findings establish condensation as a central organizing principle of CD28 costimulation and provide a biophysical framework for engineering more resilient therapeutic T cells.
SN - 0027-8424
SN - 1091-6490
ER -