A novel complement factor I involving in the complement system immune response from Lampetra morii.

Area of Science:

• Immunology
• Molecular Biology
• Marine Biology

Background:

• Complement factor I (CFI) is a critical serine protease regulating the complement system.
• Understanding CFI function in non-mammalian vertebrates like lampreys is essential for comparative immunology.

Purpose of the Study:

• To clone and characterize the complement factor I (CFI) gene from Lampetra morii (L-CFI).
• To investigate the molecular and cellular functions of L-CFI in the lamprey immune system.

Main Methods:

• Gene cloning and protein domain analysis of L-CFI.
• Tissue expression profiling of L-CFI mRNA under immune stimulation.
• Investigating the interaction between L-CFI and L-C3 protein.
• Assessing the impact of L-CFI and L-C3 depletion on serum cytotoxic activity.

Main Results:

• The L-CFI protein possesses conserved functional domains (FIMAC, SRCR, Tryp_SPc, LDLa).
• L-CFI mRNA is widely expressed, predominantly in the liver, and upregulated upon bacterial challenge (Vibrio anguillarum, Staphylococcus aureus).
• L-CFI interacts with L-C3, influencing C3 deposition and reducing serum-mediated cytotoxicity.

Conclusions:

• L-CFI plays a significant role in the innate immunity of Lampetra morii.
• L-CFI is integral to the lamprey complement system's regulatory mechanisms.