Apoptosis, or programmed cell death, occurs during normal cellular differentiation and development of multicellular organisms. Apoptosis is induced by certain cytokines including TNF and Fas ligand of the TNF family through their death domain containing receptors, TNFR1 and Fas. Cell death signals are transduced by death domain (DD)- containing adapter molecules and members of the ICE/CED-3 protease family. A novel DD-containing molecule was recently cloned from mouse, human and monkey and designated Daxx. Daxx binds specifically to the Fas death domain and enhances Fas induced apoptosis and activates the Jun N-terminal kinase (JNK) pathway. Daxx is widely expressed in fetal and adult human and mouse tissues indicating its important function in Fas signaling pathways.
