Molecular characterization of large yellow croaker (Larimichthys crocea) coagulation factor Ⅶ-like and its function...

The coagulation system is a mechanism for wound healing after injury, but it also participates in host early immune defense. The coagulation factor Ⅶ (FⅦ) can initiate extrinsic pathway and play an important role in the coagulation process. However, studies of the immune function of FVII are scarce, especially in fish. In this study, we cloned and characterized an FⅦ-like gene from large yellow croaker (Larimichthys crocea) (LcFⅦL). The open reading frame of LcFⅦL consists of 1437 base pairs and encodes 478 amino acid residues. LcFⅦL contains conserved domains that are present in other vertebrate FⅦs or FⅦLs, including a prepropeptide, a gamma-carboxy glutamic acid domain, two epidermal growth factor-like domains, and a serine protease domain. LcFⅦL was highly expressed in the liver and brain, but its expression was low in the other tested tissues. At the cellular level, LcFⅦL was highly expressed in macrophages, and its expression was induced by exposure to Pseudomonas plecoglossicida. We produced the recombinant LcFⅦL light chain (rLcFⅦL-LC), and found that it had obvious antibacterial effects against Gram-positive bacteria but low against Gram-negative bacteria. The rLcFⅦL-LC promoted the proliferation of macrophages. It also significantly induced the expression of proinflammatory factor (IL-1β and IL-6) and increased reactive oxygen species activity in large yellow croaker macrophages, while inhibited the expression of anti-inflammatory factor (TGF-β), suggesting that rLcFⅦL-LC may promote polarization of macrophages towards the M1 type. Taken together, these findings provide insight into the function of fish FⅦ, and advance our understanding of the role of the coagulation system in host defense.