title: RNA helicase Ddx5 and the noncoding RNA SRA act as coactivators in the Notch signaling pathway.
abstract: Notch signaling plays a pivotal role in embryonic and postnatal development. Upon binding of a Notch ligand, proteolytic cleavage events liberate the Notch-intracellular domain (NICD) that migrates into the nucleus. In order to activate target genes, NICD associates with the transcription factor RBP-J (also known as CSL), Mastermind and the acetyltransferase p300. Here, we identify the DEAD-box RNA helicase Ddx5 as a novel component of the RBP-J/NICD complex utilizing a biotinylation-tagging approach followed by mass-spectrometry. Biochemical assays confirm a direct interaction of Ddx5 with RBP-J. We show that Ddx5 localizes at RBP-J binding sites within the Notch target genes preTCRα, Hes1 and CD25 in a Notch-dependent manner. Moreover, knockdown of Ddx5 also downregulates a subset of Notch target genes in a murine pre T-cell model. Interestingly, also knockdown/overexpression of the RNA coactivator SRA, a cofactor of Ddx5, downregulates Hes1 and preTCRα. Using Chromatin-IP, we show that this effect is accompanied with a loss of p300 occupancy at Notch target genes and decreased histone acetylation. Together, our data demonstrate that Ddx5 and SRA function as coactivators of Notch signaling.
authors: Max-Planck-Institute of Immunobiology and Epigenetics, Freiburg, Germany.
authors: Claudia
authors: C
authors: Jung
authors: Gerhard
authors: G
authors: Mittler
authors: Franz
authors: F
authors: Oswald
authors: Tilman
authors: T
authors: Borggrefe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000378:metabolism; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000378:metabolism*; D051379:Mice; D046912:Multiprotein Complexes / Q000378:metabolism; D011485:Protein Binding; D062085:RNA, Long Noncoding / Q000235:genetics / Q000378:metabolism; D022661:RNA, Untranslated / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D018398:Homeodomain Proteins; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D046912:Multiprotein Complexes; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; C497571:Rbpj protein, mouse; D051880:Receptors, Notch; C405423:steroid receptor RNA activator; C506751:Ddx5 protein, mouse; D053487:DEAD-box RNA Helicases