The lymphocyte guard-IANs: regulation of lymphocyte survival by IAN/GIMAP family proteins.

The life-or-death decision of immune cells makes an essential contribution to immune-system development and the regulation of immune responses. A new family of cell-survival regulators expressed in lymphocytes, termed immune-associated nucleotide-binding proteins (IANs) [also known as GTPase of immunity-associated proteins (GIMAPs)], has been described. The IAN/GIMAP family consists of GTP-binding proteins that share a unique primary structure and whose expression is finely regulated by T-cell receptor signals. Recent studies have shown that IAN/GIMAP family proteins crucially regulate the survival of T cells during development, selection and homeostasis, and are possibly linked to the onset of T-lymphopenia, leukemia and autoimmunity. IAN/GIMAP family proteins might also take part in mitochondrial regulation of lymphocyte apoptosis by interacting with Bcl-2 family proteins.