IL21R

The IL21R gene encodes the interleukin-21 receptor (IL-21R), a protein that plays a critical role in the immune system. Interleukin-21 (IL-21) is a cytokine belonging to the common gamma-chain family, which also includes receptors for IL-2, IL-4, IL-7, IL-9, and IL-15. IL-21R is primarily expressed on the surface of immune cells, such as natural killer (NK) cells, T cells, B cells, and dendritic cells, where it mediates the biological effects of IL-21.

IL-21 signaling through IL-21R influences various immune responses, including the proliferation and differentiation of T cells, the activation of NK cells, and the maturation of B cells. This signaling pathway is essential for maintaining immune homeostasis and regulating adaptive immunity. Dysregulation of IL-21R signaling has been linked to autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis, as well as certain cancers, including lymphoma and multiple myeloma.

The IL21R gene is located on chromosome 16p11.2 in humans and spans approximately 10 kilobases. It consists of multiple exons, with the receptor protein being a type I transmembrane glycoprotein composed of an extracellular domain, a transmembrane region, and an intracellular signaling domain. The extracellular domain binds IL-21, initiating downstream signaling cascades that involve the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway, particularly STAT3.

Mutations or alterations in IL21R have been studied in relation to immune dysfunction and disease susceptibility. For example, genetic variations in IL21R may influence the risk of developing autoimmune disorders or affect the efficacy of immune-based therapies. Research into IL-21R continues to explore its potential as a therapeutic target for modulating immune responses in various pathological conditions.