Project description:To study the effect of Notch 1 overexpression on cell funtion and to elucidate involved signalling pathways MLE12 cells tranfected with NICD1-pIRES-dsRed2 vector were analyzed for their transcript profiles 12, 24, and 48h after transfection and related to an empty vector (EV) transfected control cells
Project description:Notch signaling is an evolutionarily conserved signal transduction pathway that is essential for metazoan development. At the molecular level, the key components of the Notch pathway are the NOTCH-family receptors, the ligands of the DSL (Delta, Serrate, Lag-2) family and the transcription factor CSL [CBF1/RBPJ, Su(H), Lag-1]. Upon ligand binding, the NOTCH Intra-Cellular Domain (NOTCH ICD) translocates into the nucleus and forms a complex with RBPJ to activate the transcription of target genes. In the absence of NOTCH ICD, RBPJ acts as a transcriptional repressor. Using a proteomic approach, we identified L3MBTL3 as a novel interactor of RBPJ. We discovered that L3MBTL3 competes with NOTCH ICD for binding to RBPJ. In the absence of NOTCH ICD, RBPJ recruits L3MBTL3 and its co-factor KDM1A [lysine (K)-specific demethylase 1A] to the promoters/enhancers of Notch target genes to promote H3K4me2 demethylation and transcriptional repression. In three distinct cell contexts in which Notch signaling governs cell fate, i.e., mature T-cells as well as brain and breast tumor cells, the loss of L3MBTL3 results in the de-repression of Notch target genes. Finally, the genetic analyses of the homologs of RBPJ and L3MBTL3 in Drosophila melanogaster and Caenorhabditis elegans demonstrate that the functional link between RBPJ/Su(H)/lag-1 and L3MBTL3/dL(3)mbt/lin-61 is evolutionarily conserved, thus identifying L3MBTL3 as a universal modulator of Notch signaling in metazoans.
