Functional characterization of a novel protein-coding circular RNA, circRNA_1193, from the mAAP gene in silkworm and its role in antiviral defense against BmCPV

作者：Li Song, Zeen Shen, Hongchuan Zhao, Xialing Chen, Qunnan Qiu, Xinyu Tong, Min Zhu, Xing Zhang, Chengliang Gong, Xiaolong Hu · 发表于：mBio · 年份：2025 · DOI：10.1128/mbio.00125-25 · 被引用次数：5 · 研究领域：Circular RNAs in diseases、Silkworms and Sericulture Research、MicroRNA in disease regulation

ABSTRACT A novel circular RNA, circRNA_1193, which originates from the membrane alanyl aminopeptidase-like gene in silkworms, was explored for its potential function and regulatory mechanism. We validated the presence of circRNA_1193 in Bombyx mori cytoplasmic polyhedrosis virus (BmCPV)-infected silkworm ovary cell line (BmN) cells through a combination of reverse transcription polymerase chain reaction, Northern blotting, and in situ hybridization. CircRNA_1193 exhibited tissue-specific expression, being highly enriched in the midgut and Malpighian tubules, and displayed a specific response to BmCPV infection, but not to Bombyx mori nucleopolyhedrovirus or lipopolysaccharide. Functional analyses revealed that the overexpression of circRNA_1193 suppressed BmCPV replication, whereas its knockdown increased viral replication. Bioinformatic analyses revealed potential internal ribosome entry sites, m6A methylation sites, and open reading frames (ORFs) within circRNA_1193, suggesting its potential coding capacity. We confirmed the translation of the ORF by constructing a DsRed reporter vector and demonstrating DsRed expression in transfected cells. Furthermore, a mutation of the start codon within circRNA_1193 abolished its antiviral activity, highlighting the crucial role of the translated protein, which is 35 kDa and is designated as VSP35. Furthermore, our data suggest that the formation of circRNA_1193 relies on reverse complementary flanking sequences. These findings unveil ...