Functional Characterization of a Cactus Homolog from the SilkwormBombyx mori

Abstract

A cDNA encoding an IB family protein was identified and the full nucleotide sequence was determined in the silkworm Bombyx mori. The IB 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 gultathione 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.

Pyrosequencing-based expression profiling and identification of differentially regulated genes from Manduca sexta, a lepidopteran model insect

“…After that, intracellular proteins are mobilized to relay signals into the cell nucleus where transcriptional regulation occurs. As shown in Table 4, we have detected increase in transcript levels of the putative pathway members: Toll-like receptors (contigs 06893 and 18001, 68% and 94% similar in amino acid sequence to ABO21763) (Ao et al, 2008), cactus (contig 01044) (Furukawa et al, 2009), relish (contigs 04802 and 15532) (Tanaka et al, 2007), and eiger (contig 01020, a membrane-bound TNF homolog) (Kauppila et al, 2003). Other intracellular proteins possibly involved in signal transduction or modulation include a Ser/Thr protein kinase, GTP/GDP exchange factors, a receptor Tyr phosphatase, a protein phosphatase 2c, ankyrin repeat proteins, and vrille transcription factor.…”

Advances in Editing Silkworms (Bombyx mori) Genome by Using the CRISPR-Cas System

“…Regarding the silkworms' innate defense mechanisms, there are two major activation pathways involved in the expression of numerous evolutionarily conserved antimicrobial peptides (AMPs) genes, and the Toll and the Imd pathways [126,127]. When Gram-negative bacterial or fungal contamination occurs, the Toll pathway is activated.…”

BmEts upregulates promoter activity of lebocin in Bombyx mori

“…The truncated BmRelish1 protein with a Flag tag at the C-terminal end was then synthesized with Transdirect insect cell (Shimadzu) using 16 mg of the synthesized RNA according to the manufacturer's instructions. The interaction between the synthesized protein and the GST fusion protein was confirmed by GST pull-down assay according to the method of Furukawa et al (2009). After SDS-polyacrylamide gel electrophoresis, the gel was transferred to Hybond ECL (GE Healthcare).…”