Chromatin-based mechanisms of dynamic gene expression/repression
Final Report Abstract
The project elucidated chromatin-based mechanisms of gene regulation by the conserved Notch signaling pathway. Upon ligand binding, the nuclear factor RBP-J activates transcription of target genes whereas in the absence of signaling, RBP-J switches off target genes expression by assembling a corepressor complex. In this project, we determined the molecular mechanism of how histone acetylation and methylation at Notch target genes are dynamically regulated. RBP-J, via its cofactor SHARP, recruits opposing complexes, the HDACs-containing NCoR corepressor complex and the KMT2D/UTX coactivator complex, which competitive recruitment is controlled by phosphorylation of chromatin modifiers. In addition to the lysine methyltransferase KMT2D, we discovered that an arginine methyltransferase, CARM1/PRMT4, is a Notch modulator. CARM1 is part of the Notch coactivator complex and directly methylates the intracellular domain of the Notch1 receptor (NICD1) at five conserved arginine residues within its activation domain. A methylation-defective NICD1 5RA mutant shows impaired ubiquitination and increased stabilization. Surprisingly, the stabilization of the NICD1 RA mutant does not result in a significant increase of its transcriptional activity compared to wildtype NICD1. Based on our biochemical and functional results, we developed a mathematical model wherein the normal NICD1 produces a short, strong transcriptional pulse, whereas the methylation-defective NICD1 mutant results in a weaker but prolonged response. Together, we propose that the above chromatin modifiers are potential targets for Notch-mediated diseases such as leukemia.
Publications
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RNA helicase Ddx5 and the noncoding RNA SRA act as coactivators in the Notch signaling pathway (2013). Biochim Biophys Acta 1833(5):1180-9
Jung, Claudia; Mittler, Gerhard; Oswald, Franz & Borggrefe, Tilman
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2014. Probing the epigenetic status at Notch target genes. Methods Mol Biol. 2014;1187:255-76
Liefke, Robert & Borggrefe, Tilman
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The tumor suppressor Ikaros shapes the repertoire of Notch target genes in T-cells (2014) Science Sign. 7:(317)
Geimer Le Lay, Anne-Solen; Oravecz, Attila; Mastio, Jérôme; Jung, Claudia; Marchal, Patricia; Ebel, Claudine; Dembélé, Doulaye; Jost, Bernard; Le Gras, Stéphanie; Thibault, Christelle; Borggrefe, Tilman; Kastner, Philippe & Chan, Susan
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(2015) Site-specific methylation of Notch1 controls amplitude and duration of the Notch1 response. Science Sign. 8(369):ra30
Hein, Kerstin; Mittler, Gerhard; Cizelsky, Wiebke; Kühl, Michael; Ferrante, Francesca; Liefke, Robert; Berger, Ina M.; Just, Steffen; Sträng, J. Eric; Kestler, Hans A.; Oswald, Franz & Borggrefe, Tilman
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(2016) A phospho-dependent mechanism involving NCoR and KMT2D controls a committed chromatin state at Notch target genes. Nucleic Acids Research, 44(10):4703-20
Oswald, Franz; Rodriguez, Patrick; Giaimo, Benedetto Daniele; Antonello, Zeus A.; Mira, Laura; Mittler, Gerhard; Thiel, Verena N.; Collins, Kelly J.; Tabaja, Nassif; Cizelsky, Wiebke; Rothe, Melanie; Kühl, Susanne J.; Kühl, Michael; Ferrante, Francesca; Hein, Kerstin; Kovall, Rhett A.; Dominguez, Maria & Borggrefe, Tilman
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. 2016. Setting the Stage for Notch: The Drosophila Su(H)-Hairless Repressor Complex. PLoS Biol. 14(7):e1002524
Borggrefe, Tilman & Oswald, Franz
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2016. The Notch intracellular domain integrates signals from Wnt, Hedgehog, TGFβ/BMP and hypoxia pathways. BBA 1863(2):303-13
Borggrefe, Tilman; Lauth, Matthias; Zwijsen, An; Huylebroeck, Danny; Oswald, Franz & Giaimo, Benedetto Daniele
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Dynamic chromatin regulation at Notch target genes. Transcription 2017 Jan;8(1):61-66
Giaimo, Benedetto Daniele; Oswald, Franz & Borggrefe, Tilman
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(2017) Dll4 and Notch signalling couples sprouting angiogenesis and artery formation. Nature Cell Biology
Pitulescu, Mara E.; Schmidt, Inga; Giaimo, Benedetto Daniele; Antoine, Tobiah; Berkenfeld, Frank; Ferrante, Francesca; Park, Hongryeol; Ehling, Manuel; Biljes, Daniel; Rocha, Susana F.; Langen, Urs H.; Stehling, Martin; Nagasawa, Takashi; Ferrara, Napoleone; Borggrefe, Tilman & Adams, Ralf H.
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(2017) Heterodimerization of AML1/ETO with CBFβ is required for leukemogenesis but not for myeloproliferation. Leukemia
Thiel, V. N.; Giaimo, B. D.; Schwarz, P.; Soller, K.; Vas, V.; Bartkuhn, M.; Blätte, T. J.; Döhner, K.; Bullinger, L.; Borggrefe, T.; Geiger, H. & Oswald, F.
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Chromatin Immunoprecipitation (ChIP) in mouse T-cell lines. Journal of Visualized Experiments (124)
Giaimo, Benedetto Daniele; Ferrante, Francesca & Borggrefe, Tilman
