12097期排列5 www.ixpcv.com The cytokine common gamma chain signal transduction is crucial for survival of activated T cells. severe combined immunodeficiency ensues and transplanted tissues are not rejected without it.Common gamma chain family cytokines serve as critical regulators of the development ,the,survival,proliferation,differentiation and function of multiple types of immune cell. These cytokines have both unique and overlapping effects on different cell types,depending primarily on the expression patterns of the cytokines and their unique receptor subunits, and the activation of different STAT proteins. Receptors and a subset of intracellular signaling molecules involved in these pathways of inactivating mutations in the common gamma chain family cytokines can lead to severe immune system disorders. The most common form of severe combined immunodeficiency, X-linked SCID, is caused by mutations in the common cytokine receptor gamma chain subunit. The gamma-chain cytokine family consists of interleukin (IL)-2, IL-4, IL-7, IL-9, IL-15 and IL-21. they signal through receptor complexes that contain the common gamma chain subunit. This subunit conjunct with different cytokine-specific receptor subunits to form unique heterodimeric receptors for IL-4, IL-7, IL-9, and IL-21, or conjunct with both IL-2/IL-15 R beta and IL-2 R alpha or IL-15 R alpha to form heterotrimeric receptors for IL-2 or IL-15, respectively. Common gamma chain family cytokines generally activate three major signaling pathways that promote cellular survival and proliferation, the PI3-K-Akt pathway, the RAS-MAPK pathway, and the JAK-STAT pathway.