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Vol. 49 No. 1, 2010
Endocytosis and NF-kB Are
Involved in the Signal Pathway of the Degranulation and Expression of
Prophenoloxidase Messenger RNA of Prawn Hemocytes Triggered by CpG
Oligodeoxynucleotides
Hung-Hung
Sung*, Pang-Hung Chen, Che-Pei Chuo, Yu-Lun Cheng, and Po-Tzung Chang
Department
of Microbiology, Soochow University, Taipei 111, Taiwan
Hung-Hung Sung, Pang-Hung Chen, Che-Pei Chuo, Yu-Lun
Cheng, and Po-Tzung Chang
(2010) Microscopic
observations showed that granulocytes were the primary
CpGoligodeoxynucleotide (ODN)-stimulated hemocyte population of the
prawn Macrobrachium rosenbergii.
To clarify whether endocytosis and the NF-kB and ERK
signal pathways are required to initiate and activate degranulation in
prawn ODN-triggered hemocytes, the total extracellular phenoloxidase
(PO) activity (POT) was examined. When hemocytes were
separately treated in vitro with ODN2006 and inhibitors of specific
signaling components, there was a decrease in the POT of hemocytes treated with either
chloroquine (1 and 2 mM), an inhibitor of endosomal acidification, or
pyrrolidine dithiocarbamate (PDTC; 5-30 μM), which inhibits the NF-kB pathway. After ERK-inhibiting
PD98059 treatment, a reduction in the POT was detected in 1/2 of all
hemocyte samples tested in this experiment; however, the POT of the
remaining samples did not significantly differ from that of the
ODN2006-stimulated sample. In addition, expression of the proPO
gene was monitored after prawns were injected with ODN2006 (5 μg/prawn)
and PDTC (1.5 mM/prawn) by a semiquantitative reverse-transcription
polymerase chain reaction analysis. The results showed that a
decreased level of prophenoloxidase (proPO) messenger RNA was detected
at 1 and 3 h post-treatment. All data suggest that in addition to
the protein kinase C-activating signaling pathway demonstrated in our
previous study, both the endocytic and NF-kB pathways are involved in activation of
the proPO system of CpG ODN-induced prawns.
Key words: Phenoloxidase,
CpG oligodeoxynucleotide, Endocytic signaling pathway, NF-kB pathway.
*Correspondence: E-mail:hhsung@scu.edu.tw
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