title: The identification of the first molluscan Akirin2 with immune defense function in the Hong Kong oyster Crassostrea hongkongensis.
abstract: The Akirin protein is a nuclear factor in the innate immune system that is highly conserved from insects to mammals and plays key roles in diverse biological processes, including immunity, myogenesis, development and the cellular stress response. However, the function of Akirins in mollusk, the second most diverse group of animals, is still poorly understood. In this study, we report the discovery of an Akirin2 gene homolog (ChAkirin2) and its biological functions in the Hong Kong oyster Crassostrea hongkongensis. ChAkirin2 is 189 amino acids in length and shares significant homology with invertebrate homologs. Phylogenetic analysis results revealed that ChAkirin2 is clustered with invertebrate Akirin2s. A sequence analysis of the 5' flanking regions of ChAkirin2 indicated that it harbors several potential PAMP-activated transcription factor binding sites (TFB), including sites for NF-κB, C/EBPα, AP-1, SRF, Oct-1 and GATA-1. An RT-PCR analysis showed that ChAkirin2 mRNA was ubiquitously expressed in various tissues and at different embryonic and larval stages. Additionally, upon infection by pathogens (Vibrio alginolyticus, Staphylococcus haemolyticus and Saccharomyces cerevisiae) and pathogen-associated molecular patterns (PAMPs: LPS, PGN and polyI:C), the expression of ChAkirin2 was significantly up-regulated. Moreover, fluorescence microscopy observations show that ChAkirin2 is located in the nuclei of HeLa cells, and the overexpression of ChAkirin2 activated the transcriptional activities of the NF-κB reporter gene in HEK293T cells. Altogether, this report provided the first experimental demonstration that mollusks possess a functional Akirin2 that is involved in the innate defense and embryogenesis processes of the oyster.
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; Graduate School of the Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.
authors.forename: Fufa
authors.initials: F
authors.lastname: Qu
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Xiang
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
authors.forename: Yuehuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China. Electronic address: carlzyu@scsio.ac.cn.
authors.forename: Ziniu
authors.initials: Z
authors.lastname: Yu
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001419:Bacteria / Q000276:immunology*; D001483:Base Sequence; D003001:Cloning, Molecular; D016000:Cluster Analysis; D049896:Crassostrea / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D017931:DNA Primers / Q000235:genetics; D005786:Gene Expression Regulation / Q000276:immunology*; D057809:HEK293 Cells; D006367:HeLa Cells; D006434:Hemocytes / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics*; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D010802:Phylogeny; D012333:RNA, Messenger / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D012097:Repressor Proteins / Q000235:genetics / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D015533:Transcriptional Activation / Q000235:genetics / Q000276:immunology
chemical_list: D017931:DNA Primers; D016328:NF-kappa B; D009687:Nuclear Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins
keywords: Akirin; Crassostrea hongkongensis; Innate immunity; NF-κB pathway