Porcine circovirus type 2 ORF5 induces an inflammatory response by up-regulating miR-21 levels through targeting nuclear ssc-miR-30d

• Published in: Virus research Vol. 346; p. 199396
• Main Authors: Li, Chang, Yang, Keli, Song, Haofei, Xia, Chuqiao, Wu, Qiong, Zhu, Jiajia, Liu, Wei, Gao, Ting, Guo, Rui, Liu, Zewen, Yuan, Fangyan, Tian, Yongxiang, Zhou, Danna
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2024; Elsevier
• Subjects: Animals; bioinformatics; Cell Line; Circoviridae Infections - genetics; Circoviridae Infections - veterinary; Circoviridae Infections - virology; Circovirus - genetics; Circovirus - physiology; cytokines; Cytokines - genetics; Cytokines - metabolism; gene expression regulation; Host-Pathogen Interactions; inflammation; Inflammation - genetics; Inflammatory response; microRNA; MicroRNAs - genetics; MicroRNAs - metabolism; mutation; NF-kappa B - genetics; NF-kappa B - metabolism; Nuclear ssc-miR-30d; ORF5; Porcine circovirus type 2; Porcine circovirus-2; Ssc-miR-21; Swine; Swine Diseases - genetics; Swine Diseases - virology; Up-Regulation; Viral Proteins - genetics; Viral Proteins - metabolism; viruses; hpi; RT‐qPCR; IL; miRNAs; IFA; Nuclear ssc-miR-30d; Ssc-miR-21; Inflammatory response; DAPI; PCV2; WB; TCID50; TNF; mAb; IκB; NF-κB; DMEM; BSA; Porcine circovirus type 2; mins; NC; ORF5; RIP; GAPDH
• ISSN: 0168-1702; 1872-7492; 1872-7492
• DOI: 10.1016/j.virusres.2024.199396

•PCV2 ORF5 promotes inflammatory responses by upregulating miR-21.•Nuclear miR-30d inhibits miR-21 by targeting pri-miR-21 to suppress the inflammation.•PCV2 ORF5 inhibits miR-30d levels by direct binding rather than the circRNA pathway. Porcine circovirus type 2 (PCV2) infection leads to multi-system inflammation in pigs, and this effect can be achieved by upregulating host miR-21. The underlying mechanism of miR-21 regulates PCV2-induced inflammation is already known, however, how PCV2 regulates miR-21 levels and function using both autonomic and host factors remains to be further revealed. Here we present the first evidence that PCV2 ORF5 induces an inflammatory response by up-regulating miR-21 level through targeting nuclear miR-30d. In this study, we found that overexpression of ORF5 significantly increased miR-21 level and promoted the expression of inflammatory cytokines and activation of the NF-κB pathway, while ORF5 mutation had the opposite effect. Moreover, the differential expression of miR-21 could significantly change the pro-inflammatory effect of ORF5, indicating that ORF5 promotes inflammatory response by up-regulating miR-21. Bioinformatics analysis and clinical detection found that nuclear miR-30d was significantly down-regulated after ORF5 overexpression and PCV2 infection, and targeted pri-miR-21 and PCV2 ORF5. Functionally, we found that miR-30d inhibited the levels of miR-21 and inflammatory cytokines in cells. Mechanistically, we demonstrated that ORF5 inhibits miR-30d expression levels through direct binding but not via the circRNA pathway, and miR-30d inhibits miR-21 levels by targeting pri-miR-21. In summary, the present study revealed the molecular mechanism of ORF5 upregulation of miR-21, further refined the molecular chain of PCV2-induced inflammatory response and elucidated the role of miRNAs in it.