Cumulative effects of weakly repressive regulatory regions in the 3' UTR maintain PD-1 expression homeostasis in...

Area of Science:

• Immunology
• Molecular Biology
• Cancer Research

Background:

• Programmed cell death protein 1 (PD-1) is a key target in cancer immunotherapy.
• The precise molecular mechanisms governing PD-1 expression homeostasis are not fully understood.

Purpose of the Study:

• To elucidate the role of the PD-1 3' untranslated region (UTR) in regulating PD-1 expression.
• To identify factors that contribute to PD-1 expression homeostasis.

Main Methods:

• Analysis of PD-1 3' UTR function in gene expression.
• Identification of RNA-binding proteins (RBPs) interacting with the PD-1 3' UTR.
• Investigation of T cell activity and T-ALL cell proliferation upon PD-1 3' UTR deletion.

Main Results:

• The PD-1 3' UTR significantly represses gene expression by promoting mRNA decay.
• Deletion of the PD-1 3' UTR impairs T cell activity and enhances T-ALL cell proliferation.
• Cumulative effects of numerous weak regulatory regions within the 3' UTR maintain PD-1 homeostasis.
• Specific RBPs (IGF2BP2, RBM38, SRSF7, SRSF4) were identified as modulators of PD-1 expression via the 3' UTR.
• PD-1 3' UTRs exhibit functional conservation and common RBP binding sites despite evolutionary divergence.

Conclusions:

• The PD-1 3' UTR plays a critical, previously unrecognized role in maintaining PD-1 expression homeostasis.
• A model is proposed where cumulative small regulatory effects orchestrate gene expression and biological outcomes.
• Findings offer potential therapeutic targets for modulating PD-1 expression in cancer.