Functional role of aspartic proteinase cathepsin D in insect metamorphosis.
BACKGROUND
Metamorphosis is a complex, highly conserved and strictly regulated development process that involves the programmed cell death of obsolete larval organs. Here we show a novel functional role for the aspartic proteinase cathepsin D during insect metamorphosis.


RESULTS
Cathepsin D of the silkworm Bombyx mori (BmCatD) was ecdysone-induced, differentially and spatially expressed in the larval fat body of the final instar and in the larval gut of pupal stage, and its expression led to programmed cell death. Furthermore, BmCatD was highly induced in the fat body of baculovirus-infected B. mori larvae, suggesting that this gene is involved in the induction of metamorphosis of host insects infected with baculovirus. RNA interference (RNAi)-mediated BmCatD knock-down inhibited programmed cell death of the larval fat body, resulting in the arrest of larval-pupal transformation. BmCatD RNAi also inhibited the programmed cell death of larval gut during pupal stage.


CONCLUSIONS
Based on these results, we concluded that BmCatD is critically involved in the programmed cell death of the larval fat body and larval gut in silkworm metamorphosis.
Gui
Zhong Zheng
ZZ
College of Natural Resources and Life Science, Dong-A University, Busan 604-714, Korea. srizzgui@hotmail.com
Lee
Kwang Sik
KS
Kim
Bo Yeon
BY
Choi
Yong Soo
YS
Wei
Ya Dong
YD
Choo
Young Moo
YM
Kang
Pil Don
PD
Yoon
Hyung Joo
HJ
Kim
Iksoo
I
Je
Yeon Ho
YH
Seo
Sook Jae
SJ
Lee
Sang Mong
SM
Guo
Xijie
X
Sohn
Hung Dae
HD
Jin
Byung Rae
BR
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015152:Blotting, Northern; D015153:Blotting, Western; D012831:Bombyx / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D002402:Cathepsin D / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D053938:DNA Fragmentation / Q000187:drug effects; D004441:Ecdysterone / Q000494:pharmacology; D005216:Fat Body / Q000201:enzymology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D008675:Metamorphosis, Biological / Q000235:genetics / Q000502:physiology*; D017924:Nucleopolyhedroviruses / Q000235:genetics; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D018411:Spodoptera
D019476:Insect Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D004441:Ecdysterone; D002402:Cathepsin D