Immune activation of apolipophorin-III and its distribution in hemocyte from Hyphantria cunea.
Apolipophorin-III (apoLp-III) is a hemolymph protein whose function is to facilitate lipid transport in an aqueous medium. Recently, apoLp-III in Galleria mellonella larvae was shown to play an unexpected role in insect immune activation. We identified the cDNA sequence of Hyphantria cunea apoLp-III by oligonucleotide-primed amplification, and 5'- and 3'-RACE PCR. Since H. cunea has an unusually low level of apoLp-III in the hemolymph, a recombinant apoLp-III was overexpressed using a baculovirus expression system to investigate its biological activity. Recombinant apoLp-III and/or Escherichia coli were injected into the hemocoel of last instar larvae, and the expression of antimicrobial peptide from fat body was determined by Northern blot. Injection of apoLp-III as well as E. coli induced slight up-regulation of its transcription rate in fat body, whereas the expression of antimicrobial peptide was dramatically induced by the injection of apoLp-III and E. coli. H. cunea hemocytes had apoLp-III in the granules and expressed its transcript, albeit at a much lower level than in the fat body. Upon bacterial injection, a subpopulation of hemocytes showed degranulation and degradation. Local discharge of apoLp-III from hemocytes caused by the injection of E. coli might be related to the immune response through an unknown mechanism.
Kim
Hong Ja
HJ
Division of Applied Life Science, Gyeongsang National University, Chinju 660 701, South Korea.
Je
Hyun Jeong
HJ
Park
Shin Yong
SY
Lee
In Hee
IH
Jin
Byung Rae
BR
Yun
Hwa Kyung
HK
Yun
Chi Young
CY
Han
Yeon Soo
YS
Kang
Young Jin
YJ
Seo
Sook Jae
SJ
D000595:Amino Acid Sequence; D000818:Animals; D001053:Apolipoproteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli / Q000276:immunology; D017344:Genes, Insect; D006434:Hemocytes / Q000378:metabolism* / Q000648:ultrastructure; D019476:Insect Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009036:Moths / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism
D001053:Apolipoproteins; D018076:DNA, Complementary; D019476:Insect Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C042470:apolipophorin III