Palmitoylation of PD-L1 Regulates Its Membrane Orientation and Immune Evasion

• Published in: Langmuir Vol. 41; no. 8; pp. 5170 - 5178
• Main Authors: Zhang, Siya, Wang, Hong-Yin, Tao, Xuan, Chen, Zhongwen, Levental, Ilya, Lin, Xubo
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 04.03.2025
• Subjects: B7-H1 Antigen - chemistry; B7-H1 Antigen - immunology; B7-H1 Antigen - metabolism; Cell Line, Tumor; Cell Membrane - metabolism; energy transfer; fluorescence; Fluorescence Resonance Energy Transfer; Humans; Immune Evasion; lipids; Lipoylation; lung neoplasms; Membrane Microdomains - chemistry; Membrane Microdomains - metabolism; molecular dynamics; Molecular Dynamics Simulation; palmitoylation; plasma membrane; T-lymphocytes; therapeutics
• ISSN: 0743-7463; 1520-5827; 1520-5827
• DOI: 10.1021/acs.langmuir.4c04441

Recently identified palmitoylation of PD-L1 is essential for immune regulation. To elucidate the underlying molecular mechanism, we performed giant plasma membrane vesicle (GPMV) experiments, μs-scale all-atom molecular dynamics (MD) simulations, fluorescence resonance energy transfer (FRET) experiments, and immune killing experiments. GPMV experiments indicated that PD-L1 palmitoylation enhanced its lipid raft affinity. MD simulations revealed dramatically different membrane orientation states of PD-L1 in liquid-ordered (L o, lipid raft) compared to liquid-disordered (L d, nonraft) membrane environments, which was validated by FRET experiments. The L d region promoted the “lie-down” orientation of PD-L1, which could inhibit its association with the PD-1 protein on immune cells and thus promote the immune killing of cancer cells. This hypothesis was supported by immune killing experiments using γδT cells as effector cells and NCI-H1299 lung cancer cells as target cells. In short, our study demonstrates that the palmitoylation affects PD-L1’s membrane localization and then membrane orientation, which thus regulates its binding with T cell PD-1 and the immune regulation. These observations may guide therapeutic strategies by explicating the regulation of immune checkpoint proteins by post-translational modifications and membrane environments.