UNC0638 inhibits SARS-CoV-2 entry by blocking cathepsin L maturation

作者：Yongjun Chen, Yujin Shi, Xiaoyan Zuo, Xiaojing Dong, Xia Xiao, Lan Chen, Zichun Xiang, Lili Ren, Zhuo Zhou, Wensheng Wei, Xiaobo Lei, Jianwei Wang · 发表于：Journal of Virology · 年份：2025 · DOI：10.1128/jvi.00741-25 · 被引用次数：1 · 研究领域：SARS-CoV-2 and COVID-19 Research、interferon and immune responses、CRISPR and Genetic Engineering

Since the outbreak of SARS-CoV-2, viral mutations have posed significant challenges in identifying therapeutic targets and developing broad-spectrum antiviral drugs. Post-translational modifications of genes involved in interferon production and signaling pathways play a crucial role in regulating interferon responses. In this study, we employed CRISPR-Cas9 screening based on adenine base editors to investigate functional amino acids in 1,278 innate immune-related genes. This approach, which converts A-T base pairs into G-C base pairs to probe the functional importance of specific amino acids, allowed us to identify 17 vital factors involved in SARS-CoV-2 infection. Among the candidate genes, genetic knockdown of EHMT2 exhibited the strongest antiviral effect. Further analysis revealed that UNC0638, a selective inhibitor of EHMT2, significantly reduced the endosomal entry of SARS-CoV-2 in pseudovirus assays. The observed inhibitory effect was consistently observed across multiple SARS-CoV-2 variants, including Alpha, Beta, Delta, and Omicron. Mechanistically, UNC0638 reduced mature cathepsin L (CTSL) levels, impairing the proteolytic cleavage of SARS-CoV-2 spike protein and subsequent membrane fusion, a critical step for viral entry. Our findings uncover EHMT2 as a host dependency factor and reveal the antiviral mechanism of EHMT2 inhibitors through CTSL maturation blockade. These results advance the understanding of host factors in SARS-CoV-2 infection and provide a strategi...