CTLA-4 Facilitates DNA Damage-Induced Apoptosis by Interacting With PP2A

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) plays a pivotal role in regulating immune responses. It accumulates in intracellular compartments, translocates to the cell surface, and is rapidly internalized. However, the cytoplasmic function of CTLA-4 remains largely unknown. Here, we describe the role of CTLA-4 as an immunomodulator in the DNA damage response to genotoxic stress. Using isogenic models of murine T cells with either sufficient or deficient CTLA-4 expression and performing a variety of assays, including cell apoptosis, cell cycle, comet, western blotting, co-immunoprecipitation, and immunofluorescence staining analyses, we show that CTLA-4 activates ataxia-telangiectasia mutated (ATM) by binding to the ATM inhibitor protein phosphatase 2A into the cytoplasm of T cells following transient treatment with zeocin, exacerbating the DNA damage response and inducing apoptosis. These findings provide new insights into how T cells maintain their immune function under high-stress conditions, which is clinically important for patients with tumors undergoing immunotherapy combined with chemoradiotherapy.

Automated summary

This study reveals the role of CTLA-4 as an immunomodulator in the DNA damage response. It activates ATM by binding to the ATM inhibitor protein 2A, exacerbates DNA damage response, and induces cell apoptosis. This provides important insights into the mechanisms by which T cells maintain immune function under high-stress conditions.