Skip to main content
. 2023 Jul 11;14:1198365. doi: 10.3389/fimmu.2023.1198365

Figure 2.

Figure 2

CTLA-4 signaling in T cell and functioning. CTLA-4 targets different molecules to inhibit T- cell activation and functioning. Once conjugated, T cell with APC initiates different signaling and T-cell proliferation and produces cytokines. CTLA-4 is expressed in cell surface of active T cells and binds with CD80/86. CTLA-4 signaling dephosphorylates TCR signaling and inhibits CD3 and ZAP70 signaling molecules and ultimately inhibits phosphorylation of GRB2 to RAS pathway. CTLA-4 inhibits Akt phosphorylation and activation and plays a negative role on the regulation of cell cycle and inhibits the transcription factors nuclear factor κB (NF-κB), AP-1, and NF-AT activation. Ligation of CTLA-4-CTLA-4Ig resumes T-cell signaling and functioning. APC, Antigen-presenting cell; AP-1, Activator protein 1; TCR, T-cell receptor; MHC, Major histocompatibility complex; CTLA-4, Cytotoxic T lymphocyte antigen 4; SYP, Tyrosine phosphatase synaptophysin; GRB2, Growth Factor Receptor-Bound 2; ZAP70, Zeta-chain associated protein kinase 70; NF-AF, Nuclear factor of activated T cells; ERK, Extracellular signal-regulated kinase; MAPK, Mitogen-activated protein kinase; PI3K, Phosphatidylinositol 3-kinase; PP2A, Protein phosphatase 2A.