Akkermansia muciniphila-derived outer membrane protein Amuc_1100 promotes acetylation of RING Finger Protein 181 promoter and mediates Autophagy Related 7 ubiquitination to activate CD8 T cells in lung adenocarcinoma.

Mounting evidence links tumor heterogeneity with gut microbiome characteristics. Akkermansia muciniphila's outer-membrane protein Amuc_1100 is emerging as a microbe-derived enhancer of antitumor immunity that boosts antitumor immunity. Considering that RNF181 may be involved in regulating the degradation of tumor immune-related proteins, we hypothesize that RNF181 may play a critical role in modulating lung adenocarcinoma (LUAD) immune microenvironment. We co-cultured LUAD cells treated with Amuc_1100 with CD8T cells to evaluate their cytotoxicity and proliferation ability (LDH detection, CFSE method), cytokine levels (ELISA), and cell surface PDL1 expression (flow cytometry). Next, the acetylation level of RNF181 and the expression of downstream substrate ATG7 in LUAD cells treated with Amuc_1100 were analyzed (qPCR, WB) to verify the ubiquitination degradation effect of RNF181 on ATG7 (WB), and its effect on PD-L1 mRNA expression was detected (qPCR). Finally, Amuc_1100 was injected into mice with normal immune function to analyze the CD3/CD8T cell ratio (flow cytometry) and changes in immune-related cytokine levels (ELISA) in LUAD tissue. LUAD cells treated with Amuc_1100 significantly increased the acetylation level of RNF181, thereby increasing the mRNA and protein expression of RNF181. Meanwhile, RNF181 can also promote the degradation of ATG7 protein through ubiquitination modification. Through these regulatory effects, Amuc_1100 can activate the immune level of LUAD and enhance its immune response ability. Amuc_1100 enhances RNF181 expression through acetylation of its promoter region. RNF181 promotes ubiquitination and degradation of ATG7, leading to downregulated PD-L1 and enhanced CD8 T cell-mediated antitumor activity.