Selectively enhanced expression of prophenoloxidase activating enzyme 1 (PPAE1) at a bacteria clearance site in the white shrimp, Litopenaeus vannamei.
BACKGROUND
The prophenoloxidase-activating (PO activating) system plays an important role in the crustacean innate immunity, particularly in wound healing and pathogen defense. A key member of this system is prophenoloxidase-activating enzyme (PPAE), which is the direct activator of prophenoloxidase (proPO). Despite their importance in crustacean PO activating system, the studies on them remain limited.


RESULTS
Here we report on a PPAE of white shrimp, Litopenaeus vannamei (lvPPAE1), which showed 94% similarity to PPAE1 of Penaeus monodon. We found that lvPPAE1 in fluid hemocytes was down regulated after challenge by Vibrio harveyi but was enhanced when shrimps were exposed to a bacteria-rich environment for long-term. In vivo gene silence of lvPPAE1 by RNAi can significantly reduce the phenoloxidase activity (PO) and increase the susceptibility of shrimps to V. harveyi. Although lvPPAE1 was down-regulated in fluid hemocytes by Vibrio challenge, its expression increased significantly in gill after bacteria injection, which is the primary bacteria-clearance tissue.


CONCLUSIONS
Suppressed expression in fluid hemocytes and enhanced expression in gill indicates selectively enhanced expression at the bacterial clearance site. This is a novel feature for PPAE expression. The results will contribute to our understanding of the PO activating system in crustaceans.
National Fisheries Research & Development Institute, #707 Eulwang dong, Jung-gu, Incheon, Republic of Korea.
In-Kwon
IK
Jang
Zhenguo
Z
Pang
Jiaping
J
Yu
Su-Kyoung
SK
Kim
Hyung-Cheol
HC
Seo
Yeong-Rok
YR
Cho
D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000276:immunology; D015870:Gene Expression; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D020868:Gene Silencing; D020022:Genetic Predisposition to Disease; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000276:immunology; D007113:Immunity, Innate / Q000235:genetics; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D033561:Penaeidae / Q000201:enzymology* / Q000276:immunology / Q000382:microbiology*; D010802:Phylogeny; D034622:RNA Interference; D016415:Sequence Alignment; D012697:Serine Endopeptidases / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D014733:Vibrio / Q000276:immunology
D012697:Serine Endopeptidases; C022435:prephenoloxidase-activating enzyme