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VLRs expression were significantly affected by complement C3 knockdown morphants in Lampetra morii
Jun Li1, Huaixiu Liu1, Qinghua Ma1
1College of Life Science, Liaoning Normal University, Dalian, 116029, China; Lamprey Research Center, Liaoning Normal University, Dalian, 116029, China; Collaborative Innovation Center of Seafood Deep Processing, Dalian Polytechnic University, Dalian, 116034, China.
Lamprey complement C3 (lmC3) is crucial for immune response, enhancing phagocytosis and defense against Aeromonas hydrophila. Knocking down lmC3 significantly impacts variable lymphocyte receptor (VLR) gene expression in Lampetra morii.
Area of Science:
- Immunology
- Evolutionary Biology
- Marine Biology
Background:
- Complement component 3 (C3) in jawless vertebrates like lampreys acts as an opsonin and participates in cytolysis.
- The precise mechanisms of C3 function and its interaction with other immune components in lampreys remain largely uncharacterized.
- This study investigates the role of C3 in the innate immune response of Lampetra morii.
Purpose of the Study:
- To identify and characterize the C3 gene in the lamprey genome.
- To determine the effect of C3 knockdown on the immune response and variable lymphocyte receptor (VLR) expression in Lampetra morii.
- To establish optimal conditions for immune stimulation experiments in lamprey larvae.
Main Methods:
- Genome-based identification of the C3 gene using orthologs, synteny, functional domains, and phylogenetic analysis.
- Determination of optimal Aeromonas hydrophila infection concentration for immune stimulation in lamprey larvae.
- Quantitative real-time PCR, immunofluorescence, and morpholino-mediated knockdown (lmC3 MO) to analyze lmC3 expression and its impact on VLR-associated genes.
Main Results:
- Lamprey C3 (lmC3) gene was identified and its expression was significantly upregulated upon Aeromonas hydrophila infection (10^7 CFU/mL).
- lmC3 knockdown larvae (lmC3 MO) exhibited increased susceptibility to A. hydrophila infection, highlighting lmC3's critical role in immunity.
- Knockdown of lmC3 significantly altered the expression of VLRA+, VLRB+, and VLRC+-associated genes, confirmed by immunohistochemical analysis.
Conclusions:
- Complement C3 is essential for the innate immune defense of Lampetra morii against bacterial infection.
- lmC3 plays a significant role in regulating the expression of variable lymphocyte receptors (VLRs) in lampreys.
- This research provides novel insights into the interplay between complement system and VLRs in jawless vertebrates.
