title: An Mpeg (macrophage expressed gene) from the Pacific oyster Crassostrea gigas: molecular characterization and gene expression.
abstract: Mpegs (macrophage expressed genes) encode members of the MACPF (membrane-attack complex/perforin) protein superfamily that play essential roles in innate immunity. In the present study, a homolog of Mpeg1 was identified in Crassostrea gigas and designed Cg-Mpeg1. The complete cDNA of Cg-Mpeg1 is 2781 bp in length, containing an ORF of 2226 bp, which encodes a putative protein of 742 amino acids with a predicted 19-aa hydrophobic signal peptide, an MACPF domain, and a transmembrane domain. Phylogenetic analysis shows that Cg-Mpeg1 is similar to other mollusk MACPF proteins and might originate in an ancient ancestor gene before the divergence of protostomes and deuterostomes. Localization study revealed that Cg-Mpeg1 protein is found primarily in late endosomes. The MACPF domain from Cg-Mpeg1 exhibits significant antibacterial activity to both Gram-negative and positive bacteria. Furthermore, Real-time Quantitative PCR analysis showed that Cg-Mpeg1 is expressed in all tissues detected with highest expression in gill and gonads. Moreover, Mpeg1 mRNA levels are significantly up-regulated following infection with Vibrio alginolyticus. These results highlight that Cg-Mpeg1 plays an essential role in host defense and elimination of pathogens in C. gigas.
authors.affiliation: Key Laboratory of Marine Bio-resources Sustainable Utilization, Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China.
authors.forename: Xiaocui
authors.initials: X
authors.lastname: He
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ziniu
authors.initials: Z
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects / Q000276:immunology; D001483:Base Sequence; D049896:Crassostrea / Q000145:classification / Q000235:genetics* / Q000276:immunology* / Q000382:microbiology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D008565:Membrane Proteins / Q000235:genetics* / Q000276:immunology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000276:immunology; D011994:Recombinant Proteins / Q000235:genetics / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D008565:Membrane Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins