Molecular evolution of the BRINP and ASTN genes and expression profles in response to pathogens and spinal cord injury repair in lamprey (Lethenteron reissneri).

Bone morphogenic protein/retinoic acid inducible neural-specific proteins (BRINPs) and astrotactins (ASTNs) are two members of membrane attack complex/perforin-like (MACPF) superfamily proteins that present high expression in the growing and mature vertebrate neurons. Lamprey has a unique evolutionary status as a representative of the oldest jawless vertebrates, making it an ideal animal model for understanding vertebrate evolution. The evolutionary origins of BRINPs and ASTNs genes in vertebrates, however, have not been shown in lampreys. Here, BRINP and ASTN genes were found in lamprey genomes and the evolutionary relationships of them were investigated by phylogenetic analysis. Protein domains, motifs, genetic structure, and crystal structure analysis revealed that the features of BRINP and ASTN appear to be conserved in vertebrates. Genomic synteny analysis indicated that lamprey BRINP and ASTN neighbor genes differed dramatically from jawed vertebrate. Real-time quantitative results illustrated that the BRINP and ASTN genes family might take part in immune defence and spinal cord injury repair. This study not only enriches a better understanding of the evolution of the BRINP and ASTN genes but also offers a foundation for exploring their roles in the development of the vertebrate central nervous system (CNS).

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

Complement factor I (CFI) is a serine protease which plays a key role in the modulation of complement system and the induced-fit factor responsible for controlling the complement-mediated processes. In this study, a CFI gene was cloned and characterized from Lampetra morii (designated as L-CFI) at molecular and cellular levels. The L-CFI protein included a factor I membrane attack complex domain (FIMAC), a scavenger receptor cysteine-rich domain (SRCR), a trypsin-like serine protease domain (Tryp_SPc) and 2 low-density lipoprotein receptor class A domains (LDLa) which would exhibit functional similarities to CFI superfamily proteins. Tissue expression profile analysis showed that L-CFI mRNA constitutively expressed in all tested tissues except erythrocytes, with the predominant expression in liver. The mRNA expression level of L-CFI increased significantly after Vibrio anguillarum and Staphylocccus aureus stimulation. It is demonstrated that L-CFI interacted with L-C3 protein and affected the deposition of L-C3 on the cell surface. Furthermore, lamprey serum after deplete L-CFI and L-C3 reduced the cytotoxic activity against HeLa cells. These findings suggest that L-CFI plays an important role in lamprey immunity and involved in the lamprey complement system.