Expression profiling of novel bacteria‐induced genes from the silkworm, Bombyx mori

Abstract

In this study, we have newly identified three bacteria-induced genes from the silkworm Bombyx mori by quantitative reverse transcriptase-polymerase chain reaction. One of these, eukaryotic initiation factor 4E-1 (eIF4E-1), is assumed to encode an eIF4E family, which plays a role in the initiation of translation as a mRNA cap-binding protein. The second gene is BmFOXG1, belonging to a family of forkhead transcription factors, FOXG1. The third gene is MBF2-related (MBF2-R) whose product has high homology to a co-activator protein MBF2 from B. mori. Although BmFOXG1 was up-regulated in the fat body in response to three kinds of bacteria, Escherichia coli, Staphylococcus aureus, and Bacillus subtilis, eIF4E-1 and MBF2-R were up-regulated by E. coli and B. subtilis, but not S. aureus, suggesting that bacteria possessing meso-diaminopimelic acid-containing peptidoglycan but not lysine-containing peptidoglycan activate eIF4E-1 and MBF2-R, probably through a conserved immune deficiency pathway. We further profiled the expression of three genes in different tissues and a silkworm cell line, NIAS-Bm-aff3, in response to bacteria, and at different times after bacterial challenge in the fat body.

Identification of MBF2 family genes in Bombyx mori and their expression in different tissues and stages and in response to Bacillus bombysepticus infection and starvation

“…In S. exigua , REPAT proteins were first found to be involved the response to B. thuringiensis and baculovirus exposure (Herrero et al ., ). Among MBF2 family members, only MBF2‐R (also known as MBF2‐9) have been established to be involved in the immune response, as it could be up‐regulated in response to E. coli and B. subtilis (Tanaka et al ., ), Therefore, additional studies will be required to determine whether the other members play a similar role in silkworms.…”

“…REPAT genes were first identified in the Spodoptera exigua midgut as being up‐regulated in response to exposure to Bacillus thuringiensis ( Bt ) toxins or baculovirus (Herrero et al ., ). In 2010, the MBF2‐related ( MBF2‐R ) gene, which exhibits high homology to a co‐activator protein MBF2 from B. mori , was verified to be up‐regulated in response to challenge by Escherichia coli and Bacillus subtilis , but not Staphylococcus aureus by preliminary microarray analysis using quantitative reverse transcription polymerase chain reaction (qRT‐PCR) (Tanaka et al ., ). However, whether MBF2 plays a direct role in immune responses in B. mori remains to be elucidated.…”

Involvement of Peptidoglycan Recognition Protein L6 in Activation of Immune Deficiency Pathway in the Immune Responsive Silkworm Cells

“…Total RNA extraction, first‐strand cDNA synthesis, and quantitative RT‐PCR were performed according to the method of Tanaka et al. (). Standard curves were generated by serial dilution of plasmid DNA, including PCR fragments.…”

Bombyx mori E26 transformation‐specific 2 (BmEts2), an Ets family protein, represses Bombyx mori Rels (BmRels)‐mediated promoter activation of antimicrobial peptide genes in the silkworm Bombyx mori

“…Total RNA extraction, first-strand cDNA synthesis and subsequent quantitative RT-PCR (qRT-PCR) were carried out according to the methods of Tanaka et al (2010). The primer pairs used for qRT-PCR were 5 0 -TCGAAGAGACACCGTGAG-3 0 and 5 0 -CGGTTCCAACAAGAAGAC-3 0 (forward and reverse primers, respectively, for ribosomal protein 49; GenBank accession number BP179699), and 5 0 -ATAATGTACGTGTACTGAG-3 0 and 5 0 -CTTACAACTTTCATTACGTTAATC-3 0 (forward and reverse primers, respectively, for BmEts2).…”