2015
Immunity 2015 Sep 15;43(3):463-74. doi: 10.1016/j.immuni.2015.07.022. Epub 2015 Aug 25.
Cytosolic Nuclease TREX1 Regulates Oligosaccharyltransferase Activity Independent of Nuclease Activity to Suppress Immune Activation.
University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; National Institute of Allergy and Infectious Diseases, NIH, Rockville, MD 20852, USA; Washington University School of Medicine, St. Louis, MO 63110, USA.
Service type: Knock-in mice
Abstract
TREX1 is an endoplasmic reticulum (ER)-associated negative regulator of innate immunity. TREX1 mutations are associated with autoimmune and autoinflammatory diseases. Biallelic mutations abrogating DNase activity cause autoimmunity by allowing immunogenic self-DNA to accumulate, but it is unknown how dominant frameshift (fs) mutations that encode DNase-active but mislocalized proteins cause disease. We found that the TREX1 C terminus suppressed immune activation by interacting with the ER oligosaccharyltransferase (OST) complex and stabilizing its catalytic integrity. C-terminal truncation of TREX1 by fs mutations dysregulated the OST complex, leading to free glycan release from dolichol carriers, as well as immune activation and autoantibody production. A connection between OST dysregulation and immune disorders was demonstrated in Trex1(-/-) mice, TREX1-V235fs patient lymphoblasts, and TREX1-V235fs knock-in mice. Inhibiting OST with aclacinomycin corrects the glycan and immune defects associated with Trex1 deficiency or fs mutation. This function of the TREX1 C terminus suggests a potential therapeutic option for TREX1-fs mutant-associated diseases.
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