Identification and characterization of Polycomb group genes in the silkworm, Bombyx mori

Abstract

Polycomb group (PcG) proteins are involved in chromatin modifications for maintaining gene repression that play important roles in the regulation of gene expression, tumorigenesis, chromosome X-inactivation, and genomic imprinting in Drosophila melanogaster, mammals, and even plants. To characterize the orthologs of PcG genes in the silkworm, Bombyx mori, 13 candidates were identified from the updated silkworm genome sequence by using the fruit fly PcG genes as queries. Comparison of the silkworm PcG proteins with those from other insect species revealed that the insect PcG proteins shared high sequence similarity. High-level expressions of all the silkworm PcG genes were maintained through day 2 to day 7 of embryogenesis, and tissue microarray data on day 3 of the fifth instar larvae showed that their expression levels were relatively low in somatic tissues, except for Enhancer of zeste (E(Z)). In addition, knockdown of each PRC2 component, such as E(Z), Extra sex combs (ESC), and Suppressor of zeste 12 (SU(Z)12), considerably decreased the global levels of H3K27me3 but not of H3K27me2. Taken together, these results suggest that insect PcG proteins are highly conserved during evolution and might play similar roles in embryogenesis.

Comparative proteomic analysis of hemolymph proteins from Autographa californica multiple nucleopolyhedrovirus (AcMNPV)-sensitive or -resistant silkworm strains during infections

“…F r d ub e-stranded RNA (dsRNA) synthesis, all the fragments were amplified from the first-strand cDNA using the gene-specific primers i c udi g a additi a T7 pr m ter seque ce at b th 5' a d 3' termi us isted i Table 3). The dsRNAs were synthesized by in vitro transcription with T7 RNA polymerase (TakaraBio, Shiga, Japan) as described previously (Li et al, 2012). The soaking RNAi in Bm5-SID1 cells were performed according to our previous study .…”

Roles of silkworm endoplasmic reticulum chaperones in the secretion of recombinant proteins expressed by baculovirus system

“…Partial cDNA fragments for the silkworm genes were amplified using specific primers (Table 1) and cloned into a dual T7 promoter-driven vector of pLits [21]. The pLits vector containing the silkworm cDNAs was used to synthesize double-stranded RNA (dsRNA) by T7 RNA polymerase in vitro and the RNA interference (RNAi) treatments were performed in above described cell lines according to our previous studies [21,22].…”

“…The pLits vector containing the silkworm cDNAs was used to synthesize double-stranded RNA (dsRNA) by T7 RNA polymerase in vitro and the RNA interference (RNAi) treatments were performed in above described cell lines according to our previous studies [21,22].…”

Cell Cycle-Dependent Recruitment of Polycomb Proteins to the ASNS Promoter Counteracts C/ebp-Mediated Transcriptional Activation in Bombyx mori

“…We previously identified the conserved 13 PcG genes in the silkworm, Bombyx mori [16]. Interestingly, our microarray analysis revealed that the asparagine synthetase ( ASNS ) gene is similarly up-regulated after RNA interference (RNAi)-meditated knockdown of some PcG genes, such as BmSCE , BmESC , BmPHO , and BmSCM (encoding a protein that can interact with BmPho and contribute to transcriptional repression), in silkworm cells [17].…”