CD27
CD27 is a member of the tumor necrosis factor receptor superfamily. It is currently of interest to immunologists as a co-stimulatory immune checkpoint molecule, and is the target of an anti-cancer drug in clinical trials.
Expression
During mouse embryonic development, specific expression levels of CD27 define the very first adult definitive hematopoietic stem cells generated in the aorta-gonad-mesonephros region. Furthermore, CD27 is expressed on both naïve and activated effector T cells as well as NK cells and activated B cells. It is a type I transmembrane protein with cysteine-rich domains, but once T cells have become activated, a soluble form of CD27 can be shed.Function
The protein encoded by this gene is a member of the TNF-receptor superfamily. This receptor is required for generation and long-term maintenance of T cell immunity. It binds to ligand CD70, and plays a key role in regulating B-cell activation and immunoglobulin synthesis.When CD27 binds CD70, a signaling cascade leads to the differentiation and clonal expansion of T cells. The cascade also results in improved survival and memory of cytotoxic T cells and increased production of certain cytokines. This receptor transduces signals that lead to the activation of NF-κB and MAPK8/JNK. Adaptor proteins TRAF2, TRAF3, and TRAF5 have been shown to mediate the signaling process of this receptor via ubiquitination. CD27-binding protein, a proapoptotic protein, can bind to this receptor and is thought to play an important role in the apoptosis induced by this receptor.
In murine γδ T cells its expression has been correlated with the secretion of IFNγ.