Dear Editor,

In this paper, authors revealed STING protein degradation through autophagy and p62/SQSTM1 signalling. cGAS/STING is a cytosolic DNA sensing pathway stimulates type I Interferon (IFN) and Interferon stimulated genes (ISGs). IFN response is essential for anti-viral and anti-cancer immunity. Main findings of this paper;

Stimulation of the cGAS-STING pathway leads to activation of autophagy; LC3 I conversation to LC3 II and autophagosomes increased after DNA stimulation.

ATG3 (autophagy-related protein) deficient cells produced elevated levels of CXCL10 (interferon stimulated inflammatory chemokine) that shows overactive STING. Inhibition of autophagy impairs DNA-stimulated degradation of STING. STING degradation occurred with stimulation of autophagy in the wildtype cells. However, ATG3 and ULK1 (autophagy initiation complex component) inhibited cells cannot degrade STING or delayed degradation after DNA stimulation.

Autophagy receptor p62 colocalized with STING to negatively control cGAS/STING pathway. Authors clearly showed that p62 is essential for degradation of K63-ubiquitinated STING. DNA-stimulated degradation of STING was dependent on both TBK1 and IRF3. Confocal microscopy analyses showed colocalization of p62-STING with cGAS/STING pathway (TBK1) and autophagy markers (LC3, and ATG9a). Authors also showed P62 dependent STING degradation during innate immune response to DNA pathogens. They infected wildtype and P62 knockout cells with Cytomegalovirus and Listeria monocytogenesis. P62 deficient cells expressed elevated levels of CXCL10 and cannot degrade STING.

Consequently, authors revealed two step model for basal autophagy and DNA stimulated autophagy for turnover of STING after activation. Termination of interferon signalling is important particularly in auto-inflammatory disease. Therefore, this is a valuable paper shedding light on controlling DNA sensing mechanisms.

There are some minor issues to improve this article.

1. Authors should clearly state the aim of the study in the abstract section.
2. Authors should outline the research question in the introduction.
3. Title can be clearer and more understandable at first reading.
4. How many mice used in the experiments? should be indicated.