TREX1 plays multiple roles in human diseases.

Three-prime repair exonuclease 1 (TREX1) is a major 3'-5' DNA exonuclease, which digests cytosolic DNA to avoid inappropriate activation of the innate immune system. Besides the most studied exonuclease activity, the recently discovered functions of TREX1, such as regulating the oligosaccharyltransferase complex and triggering proteasome-mediated degradation, are also indispensable to prevent innate immune activation. However, mounting evidence indicates a dual role of TREX1 in human diseases. In cancer and radiotherapy, the digestion of immunogenic DNA by TREX1 inhibits antitumor immunity. Moreover, TREX1 also processes specific chromosomal abnormalities upon nuclear membrane rupture, which induces DNA damage. In this review, we summarize previous studies assessing the function and mechanisms of TREX1 in autoimmune diseases, inflammatory diseases, and cancer and discuss the relationship between the function and its associated diseases. By analyzing the various roles of TREX1 under different conditions, we explored the remaining questions regarding the molecular mechanism of TREX1.