Role of the Autophagy Gene Atg5 in T Lymphocyte Survival and Proliferation

Macroautophagy (referred to as autophagy) is a highly conserved intracellular process that involves sequestration of cytoplasmic contents by intracellular double-membrane vacuoles. In the adaptive immune system, autophagy is essential for antigen presentation, survival, and activation-induced proliferation of T lymphocytes. Autophagy-related proteins, such as Atg5, Atg7, and LC3, are expressed in T lymphocytes. The basal level of autophagy occurs in resting T lymphocytes, and is enhanced in activated T cells. Both our own and other groups’ data show that the autophagy-related gene Atg5 is critical for T cell development, survival, and function. The mitochondrial content of Atg5-deficient naive T lymphocytes is abnormally high, which leads to defective survival. These findings suggest that autophagy is critical for promoting T lymphocyte survival by regulating intracellular organelle homeostasis.