ATF4 Regulates CD4⁺ T Cell Immune Responses through Metabolic Reprogramming

Area of Science:

• Immunology
• Cellular Metabolism
• Molecular Biology

Background:

• T cell function is significantly influenced by oxidative environments and amino acid availability.
• The metabolic reprogramming strategies employed by T cells under stress are not fully elucidated.

Purpose of the Study:

• To investigate the role of Activating Transcription Factor 4 (ATF4) in CD4+ T cell metabolic adaptation to stress.
• To understand how ATF4 influences T cell homeostasis, proliferation, differentiation, and immune responses.

Main Methods:

• Analysis of ATF4 induction in CD4+ T cells under oxidizing conditions and amino acid starvation.
• Assessment of cellular functions (redox homeostasis, proliferation, differentiation, cytokine production) in Atf4-deficient CD4+ T cells.
• Gene network analysis regulated by ATF4.
• Evaluation of immune responses and experimental allergic encephalomyelitis (EAE) in Atf4-deficient mice.

Main Results:

• Oxidizing environments and amino acid starvation induce ATF4 in CD4+ T cells.
• Atf4 deficiency impairs T cell redox homeostasis, proliferation, differentiation, and cytokine production.
• ATF4 orchestrates a gene network promoting amino acid uptake, mTORC1 activation, protein synthesis, de novo amino acid and glutathione synthesis, and catabolic pathways (glycolysis, glutaminolysis, oxidative phosphorylation).
• ATF4 supports anabolic pathways by providing energy and precursors from catabolic processes.

Conclusions:

• ATF4 is a critical regulator of CD4+ T cell metabolism, adapting to extracellular stress.
• ATF4 is essential for robust T cell-mediated immunity, including Th1 and Th17 responses.
• ATF4 plays a protective role in autoimmune diseases like EAE by modulating T cell responses.