Antimicrobial activity of a novel hypervariable immunoglobulin domain-containing receptor Dscam in Cherax quadricarinatus.
Down syndrome cell adhesion molecule (Dscam) mediates innate immunity against pathogens in arthropods. Here, a novel Dscam from red claw crayfish Cherax quadricarinatus (CqDscam) was isolated. The CqDscam protein contains one signal peptide, ten immunoglobulin domains, six fibronectin type III domains, one transmembrane domain and cytoplasmic tail. CqDscam phylogenetically clustered with other invertebrate Dscams. Variable regions of CqDscam in N-terminal halves of Ig2 and Ig3 domains, complete Ig7 domain and TM domain can be reshuffled after transcription to produce a deluge of >37,620 potential alternative splice forms. CqDscam was detected in all tissues tested and abundantly expressed in immune system and nerve system. Upon lipopolysaccharides (LPS) and b-1, 3-glucans (Glu) challenged, the expression of CqDscam was up-regulated, while no response in expression occurred after injection with peptidoglycans (PG). Membrane-bound and secreted types of CqDscam were separated on the protein level, and were both extensively induced post LPS challenge. Membrane-bound CqDscam protein was not detected in the serum, but localized to the hemocyte surface by immuno-localization assay. In the antimicrobial assays, the recombinant LPS-induced isoform of CqDscam protein displayed bacterial binding and growth inhibitory activities, especially with Escherichia coli. These results suggested that CqDscam, as one of pattern-recognition receptors (PRRs), involved in innate immune recognition and defense mechanisms in C. quadricarinatus, possibly through alternative splicing.
Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai, China.
Dan
D
Li
Shanghai Fisheries Technical Extension Station, Shanghai Fisheries Research Institute, Shanghai, China.
Ai-Qing
AQ
Yu
Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai, China.
Xue-Jie
XJ
Li
Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai, China.
You-Ting
YT
Zhu
Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai, China.
Xing-Kun
XK
Jin
Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai, China. Electronic address: liweiwei85@gmail.com.
Wei-Wei
WW
Li
Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Science, East China Normal University, Shanghai, China. Electronic address: qwang@bio.ecnu.edu.cn.
Qun
Q
Wang
D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D060829:Arthropod Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003400:Astacoidea / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry; D008070:Lipopolysaccharides / Q000502:physiology; D008969:Molecular Sequence Data; D010457:Peptidoglycan / Q000378:metabolism; D010802:Phylogeny; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry; D016415:Sequence Alignment; D013211:Staphylococcus aureus / Q000737:chemistry; D015054:Zymosan / Q000502:physiology
D000890:Anti-Infective Agents; D060829:Arthropod Proteins; D015815:Cell Adhesion Molecules; D018076:DNA, Complementary; D008070:Lipopolysaccharides; D010457:Peptidoglycan; D011994:Recombinant Proteins; D015054:Zymosan
Antibacterial; Cherax quadricarinatus; Dscam; PAMPs