Cyclic GMP-AMP synthase (cGAS) initiates the innate immune system in response to cytosolic dsDNA. After binding and activation from dsDNA, cGAS uses ATP and GTP to synthesize 2′, 3′ -cGAMP (cGAMP), a cyclic dinucleotide second messenger with mixed 2′-5′ and 3′-5′ phosphodiester bonds. Inappropriate stimulation of cGAS has been implicated in autoimmune disease such as systemic lupus erythematosus, thus inhibition of cGAS may be of therapeutic benefit in some diseases; however, the size and polarity of the cGAS active site makes it a challenging target for the development of conventional substrate-competitive inhibitors. We report here the development of a high affinity (KD = 200 nM) inhibitor from a low affinity fragment hit with supporting biochemical and structural data showing these molecules bind to the cGAS active site. We also report a new high throughput cGAS fluorescence polarization (FP)-based assay to enable the rapid identification and optimization of cGAS inhibitors. This FP assay uses Cy5-labelled cGAMP in combination with a novel high affinity monoclonal antibody that specifically recognizes cGAMP with no cross reactivity to cAMP, cGMP, ATP, or GTP. Given its role in the innate immune response, cGAS is a promising therapeutic target for autoinflammatory disease. Our results demonstrate its druggability, provide a high affinity tool compound, and establish a high throughput assay for the identification of next generation cGAS inhibitors.

Introduction: A pandemic with the severity of COVID-19 affects people's lives physically, as well as their daily routines, views of the world, and emotional balance. Lockdown is often an unpleasant experience due to a separation from loved ones, loss of freedom, and uncertainty over the disease status. To adjust, individuals and groups have had to adapt their perceptions of the event to the current scenario. This study aims to describe the perceptions of confined people on the changes occurring in their lives in the aftermath of the COVID-19 lockdown.Methods: A total of 1,534 individuals (26.6% men; 73.4% women; mean age 41.6) responded to the questionnaire comprising 19 closed and five open-ended questions about the changes they anticipated in their lives in the immediate post-confinement era.Results: Two definite groups appeared in the results: those who lived the confinement pleasantly, and those for which it was painful. They differ according to their confinement conditions and perceived degree of exposure to the virus. There seems to be a link for those who had a pleasant experience to a lower perceived exposure to the virus and less burdensome confinement conditions (young children, surface area, etc.). Lockdown conditions seem to influence the respondents' perceptions: a pleasant experience is associated with a vision of the society's evolution at large, and the care about its economic and professional progress; a painful one is associated more with focusing on the immediate needs of social support and personal well-being.Discussion: Emotional experience during lockdown impacts the perception of its aftermath, with hope and anxiety becoming two ways of coping with uncertainty.

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