Exploring the Role of a Novel Interleukin-17 Homolog from Invertebrate Marine Mussel Mytilus coruscus in Innate Immune Response: Is Negative Regulation by Mc -Novel_miR_145 the Key?

Interleukin-17 (IL-17) represents a class of proinflammatory cytokines involved in chronic inflammatory and degenerative disorders. Prior to this study, it was predicted that an IL-17 homolog could be targeted by Mc -novel_miR_145 to participate in the immune response of Mytilus coruscus . This study employed a variety of molecular and cell biology research methods to explore the association between Mc -novel_miR_145 and IL-17 homolog and their immunomodulatory effects. The bioinformatics prediction confirmed the affiliation of the IL-17 homolog with the mussel IL-17 family, followed by quantitative real-time PCR assays (qPCR) to demonstrate that Mc IL-17-3 was highly expressed in immune-associated tissues and responded to bacterial challenges. Results from luciferase reporter assays confirmed the potential of Mc IL-17-3 to activate downstream NF-κb and its targeting by Mc -novel_miR_145 in HEK293 cells. The study also produced Mc IL-17-3 antiserum and found that Mc -novel_miR_145 negatively regulates Mc IL-17-3 via western blotting and qPCR assays. Furthermore, flow cytometry analysis indicated that Mc -novel_miR_145 negatively regulated Mc IL-17-3 to alleviate LPS-induced apoptosis. Collectively, the current results showed that Mc IL-17-3 played an important role in molluscan immune defense against bacterial attack. Furthermore, Mc IL-17-3 was negatively regulated by Mc -novel_miR_145 to participate in LPS-induced apoptosis. Our findings provide new insights into noncoding RNA regulation in invertebrate models.