Tumor necrosis factor receptor superfamily member 18 (TNFRSF18) also known as activation-inducible TNFR family receptor (AITR) or glucocorticoid-induced TNFR-related protein (GITR) is a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that in humans is encoded by the TNFRSF18 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

Function

TNFRSF18 is a member of the tumor necrosis factor receptor

Tumor necrosis factor receptor

A tumor necrosis factor receptor , or death receptor, is a trimeric cytokine receptor that binds tumor necrosis factors . The receptor cooperates with an adaptor protein , which is important in determining the outcome of the response A tumor necrosis factor receptor (TNFR), or death receptor, is a...

 (TNF-R) superfamily. This receptor has been shown to have increased expression upon T-cell activation, and it is thought to play a key role in dominant immunological self-tolerance maintained by CD25

CD25

CD25 is the alpha chain of the IL-2 receptor. It is a type I transmembrane protein present on activated T cells, activated B cells, some thymocytes, myeloid precursors, and oligodendrocytes that associates with CD122 to form a heterodimer that can act as a high-affinity receptor for IL-2.CD25 is...

⁺/CD4

CD4

CD4 is a glycoprotein expressed on the surface of T helper cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and was originally known as leu-3 and T4 before being named CD4 in 1984...

⁺ regulatory T cells. Knockout studies in mice also suggest the role of this receptor is in the regulation of CD3-driven T-cell activation and programmed cell death

Programmed cell death

Programmed cell-death is death of a cell in any form, mediated by an intracellular program. PCD is carried out in a regulated process which generally confers advantage during an organism's life-cycle...

. Three alternatively spliced transcript variants of this gene encoding distinct isoforms have been reported.

AITR

Human activation-inducible tumor necrosis factor receptor (AITR) and its ligand, AITRL, are important costimulatory molecules in the pathogenesis of autoimmune diseases. Despite the importance of these costimulatory molecules in autoimmune disease, their role in the autoimmune reaction to herniated disc fragments has yet to be explored.

GITR

GITR was identified as a new member of the TNF receptor superfamily, by comparing gene expression in untreated and DEX-treated murine T-cell lines. GITR can also be induced when T cells are activated. Although mouse GITR is induced by either GC engagement or T-cell activation, its human homologue (hGITR/AITR) is upregulated only by activation. Therefore, the requirements for GR signaling in inducing GITR expression by T cells remain moot .

GITR (glucocorticoid

Glucocorticoid

Glucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor , which is present in almost every vertebrate animal cell...

-induced tumor necrosis factor receptor) is a surface receptor molecule that has been shown to be involved in inhibiting the suppressive activity of T-regulatory cells and extending the survival of T-effector cells. In mouse models, GITR was initially noted to be selectively enriched on the surface of regulatory T cells, making this an attractive potential surface marker for these rare cells. However, subsequent studies revealed GITR to also be up-regulated on any activated T cells in humans, thus undermining its utility as a regulatory T cell marker.

Further reading