TRIM21 Knockout Cell Line (A549)

Acute respiratory infections caused by influenza A virus (IAV) spread widely and lead to substantial morbidity and mortality. Host cell induction of type I interferon (IFN-I) plays a fundamental role in eliminating the virus during the innate antiviral response. The potential role of N-myc and STAT interactor (NMI) and its underlying mechanisms of action during IAV infection, however, remain elusive. In this study, we found that the expression of NMI increased after IAV infection. -knockout mice infected with IAV displayed increased survival rate, decreased weight loss, lower viral replication, and attenuated lung inflammation when compared with wild-type mice. Deficiency of NMI promoted the production of IFN-I and IFN-stimulated genes and . Reduced levels of NMI also resulted in an increase of the expression of IFN regulator factor (IRF) 7. Further studies have revealed that NMI could interact with IRF7 after IAV infection, and this interaction involved its NID1 and NID2 domain. In addition, NMI facilitated ubiquitination and proteasome-dependent degradation of IRF7 through recruitment of the E3 ubiquitin ligase TRIM21 (tripartite motif-containing 21) to limit the IAV-triggered innate immunity. Our findings reveal a clearer understanding of the role of NMI in regulating the host innate antiviral response and provide a potential therapeutic target for controlling IAV infection.

Acute lung injury (ALI) is a severe complication of sepsis, and its underlying pathological mechanisms remain poorly understood. This study aims to investigate the role and mechanisms by which IRGM mediates autophagy through the regulation of the AKT/mTOR signaling pathway in sepsis-induced ALI. Initially, a sepsis-induced ALI mouse model was established using cecal ligation and puncture (CLP). Our results demonstrated that Irgm1 expression was significantly upregulated in the ALI model. Subsequently, Irgm1 was knocked down in vivo using AAV vectors, and changes in ALI symptoms were assessed. In vitro, a sepsis-induced ALI cell model was generated by stimulating A549 cells with lipopolysaccharide (LPS). The effects of IRGM overexpression on autophagy and apoptosis were evaluated, and its impact on the AKT/mTOR signaling pathway was analyzed. Furthermore, mass spectrometry and co-immunoprecipitation (COIP) experiments were conducted to explore the interaction between IRGM and TRIM21. In vivo results showed that Irgm1 knockout exacerbated CLP-induced ALI, as evidenced by a significant reduction in autophagic activity, increased apoptosis, and aberrant activation of the AKT/mTOR pathway. Further cellular experiments suggested that IRGM may enhance autophagy by inhibiting the AKT/mTOR signaling pathway, thereby attenuating LPS-induced cell damage. Additionally, COIP experiments revealed that IRGM interacts with TRIM21 to inhibit AKT/mTOR pathway activation, thereby promoting autophagy and mitigating sepsis-induced ALI. In conclusion, IRGM regulates autophagy through the AKT/mTOR signaling pathway and exerts protective effects in sepsis-induced ALI, suggesting that it may serve as a potential therapeutic target for sepsis-related ALI.