SESN1 negatively regulates STING1 to maintain innate immune homeostasis.

STING1 is a central hub protein of CGAS-STING1 signaling which is important signaling axis to sense DNA for the host against pathogens infection through regulating type I interferon (IFN-I) production. However, excessive STING1 activation-induced overproduced IFN-I triggers tissue damage and autoimmune disorders. Thus, the activity of STING1 must be precisely regulated for immune homeostasis. Here, we discovered SESN1 (sestrin 1) as an essential negative regulator of STING1 to maintain immune homeostasis. Upon herpes simplex virus-1 (HSV-1) infection, the expression of SESN1 was downregulated, which enhanced potentiality to virus defense for host. Consistently, SESN1-deficient mice exhibited stronger ability against HSV-1 infection compared to wild-type littermates. Additionally, we found the expression of SESN1 was decreased in systemic lupus erythematosus (SLE) patients and trex1 KO mouse model of autoimmune disease. Intriguingly, the replenishment of SESN1 effectively impressed IFN-I production and autoimmune responses in the PBMCs of human SLE specimens and the trex1 KO mouse model both in vitro and in vivo. Mechanistically, SESN1 targeted STING1 and promoted STING1 autophagic degradation by facilitating the interaction of SQSTM1/p62 and STING1. Together, our study uncovers a crucial role of SESN1 for immune homeostasis to balance anti-virus and autoimmunity by regulating STING1. SESN1 might be a potential therapeutic target for infectious and autoimmune diseases.Abbreviations: BMDMs: bone marrow-derived macrophages; cGAMP: cyclic GMP-AMP; CGAS: cyclic GMP-AMP synthase; HTDNA: herring testes DNA; IFNA4: interferon alpha 4; IFNB: interferon beta; IRF3: interferon regulatory factor 3; ISD: interferon stimulatory DNA; ISGs: IFN-stimulated genes; PBMCs: peripheral blood mononuclear cells; RSAD2: radical S-adenosyl methionine domain containing 2; SLE: systemic lupus erythematosus; STING1: stimulator of interferon response cGAMP interactor 1; TBK1: TANK binding kinase 1.