Tight nuclear tethering of cGAS is essential for preventing autoreactivity

• Published in: eLife Vol. 8
• Main Authors: Volkman, Hannah E, Cambier, Stephanie, Gray, Elizabeth E, Stetson, Daniel B
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 06.12.2019; eLife Sciences Publications Ltd; eLife Sciences Publications, Ltd
• Subjects: Animals; Antiviral drugs; antiviral immunity; Autoimmunity; Bone marrow; Cell cycle; Cell division; Cell Line, Tumor; Cell Nucleus - genetics; Cell Nucleus - metabolism; Cells, Cultured; cGAS; Chromatin; Cytosol; Cytosol - enzymology; Deoxyribonucleic acid; DNA; DNA - genetics; DNA - metabolism; DNA Cleavage; DNA Damage; EDTA; Genomics; HeLa Cells; Humans; Immunoglobulins; Immunology and Inflammation; innate Immunity; Kinases; Localization; Mice, Inbred C57BL; Microscopy; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; nucleic acid detection; Nucleotidyltransferases - genetics; Nucleotidyltransferases - metabolism; Protein Binding; Proteins; Canada; nucleic acid detection; mouse; innate Immunity; antiviral immunity; inflammation; cGAS; human; immunology
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.47491

cGAS is an intracellular innate immune sensor that detects double-stranded DNA. The presence of billions of base pairs of genomic DNA in all nucleated cells raises the question of how cGAS is not constitutively activated. A widely accepted explanation for this is the sequestration of cGAS in the cytosol, which is thought to prevent cGAS from accessing nuclear DNA. Here, we demonstrate that endogenous cGAS is predominantly a nuclear protein, regardless of cell cycle phase or cGAS activation status. We show that nuclear cGAS is tethered tightly by a salt-resistant interaction. This tight tethering is independent of the domains required for cGAS activation, and it requires intact nuclear chromatin. We identify the evolutionarily conserved tethering surface on cGAS and we show that mutation of single amino acids within this surface renders cGAS massively and constitutively active against self-DNA. Thus, tight nuclear tethering maintains the resting state of cGAS and prevents autoreactivity.