Transcription of bxd noncoding RNAs promoted by trithorax represses Ubx in cis by transcriptional interference.
Much of the genome is transcribed into long noncoding RNAs (ncRNAs). Previous data suggested that bithoraxoid (bxd) ncRNAs of the Drosophila bithorax complex (BX-C) prevent silencing of Ultrabithorax (Ubx) and recruit activating proteins of the trithorax group (trxG) to their maintenance elements (MEs). We found that, surprisingly, Ubx and several bxd ncRNAs are expressed in nonoverlapping patterns in both embryos and imaginal discs, suggesting that transcription of these ncRNAs is associated with repression, not activation, of Ubx. Our data rule out siRNA or miRNA-based mechanisms for repression by bxd ncRNAs. Rather, ncRNA transcription itself, acting in cis, represses Ubx. The Trithorax complex TAC1 binds the Ubx coding region in nuclei expressing Ubx, and the bxd region in nuclei not expressing Ubx. We propose that TAC1 promotes the mosaic pattern of Ubx expression by facilitating transcriptional elongation of bxd ncRNAs, which represses Ubx transcription.
Petruk
Svetlana
S
Department of Biochemistry, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Sedkov
Yurii
Y
Riley
Kristen M
KM
Hodgson
Jacob
J
Schweisguth
Francois
F
Hirose
Susumu
S
Jaynes
James B
JB
Brock
Hugh W
HW
Mazo
Alexander
A
D000818:Animals; D002467:Cell Nucleus; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D017344:Genes, Insect; D006657:Histones / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D022661:RNA, Untranslated / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors / Q000378:metabolism
D002868:Chromosomal Proteins, Non-Histone; D029721:Drosophila Proteins; D006657:Histones; D018398:Homeodomain Proteins; D022661:RNA, Untranslated; C483403:TAC1 protein, Drosophila; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; C066177:Ubx protein, Drosophila; C512571:trx protein, Drosophila