title: Genome-wide identification of polycomb target genes reveals a functional association of Pho with Scm in Bombyx mori.
abstract: Polycomb group (PcG) proteins are evolutionarily conserved chromatin modifiers and act together in three multimeric complexes, Polycomb repressive complex 1 (PRC1), Polycomb repressive complex 2 (PRC2), and Pleiohomeotic repressive complex (PhoRC), to repress transcription of the target genes. Here, we identified Polycomb target genes in Bombyx mori with holocentric centromere using genome-wide expression screening based on the knockdown of BmSCE, BmESC, BmPHO, or BmSCM gene, which represent the distinct complexes. As a result, the expressions of 29 genes were up-regulated after knocking down 4 PcG genes. Particularly, there is a significant overlap between targets of BmPho (331 out of 524) and BmScm (331 out of 532), and among these, 190 genes function as regulator factors playing important roles in development. We also found that BmPho, as well as BmScm, can interact with other Polycomb components examined in this study. Further detailed analysis revealed that the C-terminus of BmPho containing zinc finger domain is involved in the interaction between BmPho and BmScm. Moreover, the zinc finger domain in BmPho contributes to its inhibitory function and ectopic overexpression of BmScm is able to promote transcriptional repression by Gal4-Pho fusions including BmScm-interacting domain. Loss of BmPho expression causes relocalization of BmScm into the cytoplasm. Collectively, we provide evidence of a functional link between BmPho and BmScm, and propose two Polycomb-related repression mechanisms requiring only BmPho associated with BmScm or a whole set of PcG complexes.
authors.affiliation: Laboratory of Silkworm Science, Kyushu University Graduate School of Bioresource and Bioenvironmental Sciences, Fukuoka, Japan.
authors.forename: Zhiqing
authors.initials: Z
authors.lastname: Li
authors.forename: Daojun
authors.initials: D
authors.lastname: Cheng
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Mon
authors.forename: Tsuneyuki
authors.initials: T
authors.lastname: Tatsuke
authors.forename: Li
authors.initials: L
authors.lastname: Zhu
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.forename: Jae Man
authors.initials: JM
authors.lastname: Lee
authors.forename: Qingyou
authors.initials: Q
authors.lastname: Xia
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kusakabe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D012831:Bombyx / Q000235:genetics*; D049109:Cell Proliferation; D002478:Cells, Cultured; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D049750:Genome, Insect; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D063146:Polycomb-Group Proteins; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D021381:Protein Transport; D034622:RNA Interference; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D019476:Insect Proteins; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D008156:Luciferases