A Nuclear Export Signal Is Required for cGAS to Sense Cytosolic DNA

Cell Rep. 2021 Jan 5;34(1):108586. doi: 10.1016/j.celrep.2020.108586.

Abstract

The cyclic GMP-AMP (cGAMP) synthase (cGAS) is a key DNA sensor that initiates STING-dependent signaling to produce type I interferons through synthesizing the secondary messenger 2'3'-cGAMP. In this study, we confirm previous studies showing that cGAS is located both in the cytoplasm and in the nucleus. Nuclear accumulation is observed when leptomycin B is used to block the exportin, CRM1 protein. As a result, leptomycin B impairs the production of interferons in response to DNA stimulation. We further identify a functional nuclear export signal (NES) in cGAS, 169LEKLKL174. Mutating this NES leads to the sequestration of cGAS within the nucleus and the loss of interferon response to cytosolic DNA treatment, and it further determines the key amino acid to L172. Collectively, our data demonstrate that the cytosolic DNA-sensing function of cGAS depends on its presence within the cytoplasm, which is warranted by a functional NES.

Keywords: DNA sensor; cGAS; innate immune system; nuclear export signal.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cytosol / metabolism*
  • DNA / metabolism*
  • Exportin 1 Protein
  • Fatty Acids, Unsaturated / pharmacology
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Immunity, Innate
  • Interferon Type I / drug effects
  • Interferon Type I / metabolism
  • Interferon-beta / metabolism
  • Karyopherins / drug effects
  • Karyopherins / immunology
  • Karyopherins / metabolism*
  • Membrane Proteins / metabolism
  • Mutation
  • Nuclear Export Signals*
  • Nucleotides, Cyclic / metabolism*
  • Nucleotidyltransferases / genetics*
  • Nucleotidyltransferases / immunology
  • Nucleotidyltransferases / metabolism*
  • Receptors, Cytoplasmic and Nuclear / drug effects
  • Receptors, Cytoplasmic and Nuclear / immunology
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Signal Transduction
  • THP-1 Cells

Substances

  • Fatty Acids, Unsaturated
  • Interferon Type I
  • Karyopherins
  • Membrane Proteins
  • Nuclear Export Signals
  • Nucleotides, Cyclic
  • Receptors, Cytoplasmic and Nuclear
  • STING1 protein, human
  • cyclic guanosine monophosphate-adenosine monophosphate
  • Interferon-beta
  • DNA
  • Nucleotidyltransferases
  • cGAS protein, human
  • leptomycin B

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