Functional characterization of a cactus homolog from the silkworm Bombyx mori.
A cDNA encoding an IkappaB family protein was identified and the full nucleotide sequence was determined in the silkworm Bombyx mori. The IkappaB gene, designated BmCactus, was constitutively expressed mainly in the fat body and hemocytes. Transfection experiments on a B. mori cell line, NIAS-Bm-aff3, with expression vectors containing BmCactus, BmRelA, BmRelB, or the active portion of BmRelish1 showed that activation of the CecB1 gene promoter by either BmRelA or BmRelB, but not the active portion of BmRelish1, was strongly inhibited by BmCactus. In addition, activation of CecB1 gene by autoclaved E. coli in the cultured cells was observed regardless of the presence or absence of BmCactus. A glutathione S-transferase pull-down assay and analysis using a yeast two-hybrid system demonstrated that BmCactus interacted with the BmRel Rel homology domain, but not with the BmRelish Rel homology domain. These results suggest that BmCactus is involved in the Toll signal transduction pathway in B. mori.
Furukawa
Seiichi
S
Innate Immunity Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan.
Tanaka
Hiromitsu
H
Ishibashi
Jun
J
Imanishi
Shigeo
S
Yamakawa
Minoru
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D012831:Bombyx; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry*; D029721:Drosophila Proteins / Q000737:chemistry*; D004926:Escherichia coli / Q000235:genetics; D005786:Gene Expression Regulation; D005982:Glutathione Transferase / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010750:Phosphoproteins / Q000737:chemistry*; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D051193:Toll-Like Receptors / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D010750:Phosphoproteins; D051193:Toll-Like Receptors; C077938:cact protein, Drosophila; D005982:Glutathione Transferase