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• Lemma, Roza Berhanu; Ledsaak, Marit; Fuglerud, Bettina Maria; Rodriguez- Castañeda, Fernando; Eskeland, Ragnhild & Gabrielsen, Odd Stokke (2023). MYB regulates the SUMO protease SENP1 and its novel interaction partner UXT, modulating MYB target genes and the SUMO landscape. Journal of Biological Chemistry. ISSN 0021-9258. 299(9). doi: 10.1016/j.jbc.2023.105062. Full text in Research Archive Show summary

  SUMOylation is a post-translational modification frequently found on nuclear proteins, including transcription factors (TFs) and coactivators. By controlling the activity of several TFs, SUMOylation may have far-reaching effects. MYB is an example of a developmental TF subjected to SUMO-mediated regulation, through both SUMO conjugation and SUMO binding. How SUMO affects MYB target genes is unknown. Here, we explored the global effect of reduced SUMOylation of MYB on its downstream gene programs. RNA-Seq in K562 cells after MYB knockdown and rescue with mutants having an altered SUMO status revealed a number of differentially regulated genes and distinct gene ontology term enrichments. Clearly, the SUMO status of MYB both quantitatively and qualitatively affects its regulome. The transcriptome data further revealed that MYB upregulates the SUMO protease SENP1, a key enzyme that removes SUMO conjugation from SUMOylated proteins. Given this role of SENP1 in the MYB regulome, we expanded the analysis, mapped interaction partners of SENP1, and identified UXT as a novel player affecting the SUMO system by acting as a repressor of SENP1. MYB inhibits the expression of UXT suggesting that MYB is able not only to control a specific gene program directly but also indirectly by affecting the SUMO landscape through SENP1 and UXT. These findings suggest an autoactivation loop whereby MYB, through enhancing SENP1 and reducing UXT, is itself being activated by a reduced level of repressive SUMOylation. We propose that overexpressed MYB, seen in multiple cancers, may drive this autoactivation loop and contribute to oncogenic activation of MYB.

• Fuglerud, Bettina Maria; Drissler, Sibyl; Lotto, Jeremy; Stephan, Tabea L.; Thakur, Avinash & Cullum, Rebecca [Show all 7 contributors for this article] (2022). SOX9 reprograms endothelial cells by altering the chromatin landscape. Nucleic Acids Research (NAR). ISSN 0305-1048. 50(15), p. 8547–8565. doi: 10.1093/nar/gkac652. Full text in Research Archive
• Lemma, Roza Berhanu; Ledsaak, Marit; Fuglerud, Bettina Maria; Sandve, Geir Kjetil; Eskeland, Ragnhild & Gabrielsen, Odd Stokke (2021). Chromatin occupancy and target genes of the haematopoietic master transcription factor MYB. Scientific Reports. ISSN 2045-2322. 11(9008). doi: 10.1038/s41598-021-88516-w. Full text in Research Archive Show summary

  The transcription factor MYB is a master regulator in haematopoietic progenitor cells and a pioneer factor affecting differentiation and proliferation of these cells. Leukaemic transformation may be promoted by high MYB levels. Despite much accumulated molecular knowledge of MYB, we still lack a comprehensive understanding of its target genes and its chromatin action. In the present work, we performed a ChIP-seq analysis of MYB in K562 cells accompanied by detailed bioinformatics analyses. We found that MYB occupies both promoters and enhancers. Five clusters (C1–C5) were found when we classified MYB peaks according to epigenetic profiles. C1 was enriched for promoters and C2 dominated by enhancers. C2-linked genes were connected to hematopoietic specific functions and had GATA factor motifs as second in frequency. C1 had in addition to MYB-motifs a significant frequency of ETS-related motifs. Combining ChIP-seq data with RNA-seq data allowed us to identify direct MYB target genes. We also compared ChIP-seq data with digital genomic footprinting. MYB is occupying nearly a third of the super-enhancers in K562. Finally, we concluded that MYB cooperates with a subset of the other highly expressed TFs in this cell line, as expected for a master regulator

• Thakur, Avinash; Wong, Jasper C.H.; Wang, Evan Y.; Lotto, Jeremy; Kim, Donghwan & Cheng, Jung-Chien [Show all 20 contributors for this article] (2019). Hepatocyte nuclear factor 4-alpha is essential for the active epigenetic state at enhancers in mouse liver. Hepatology. ISSN 0270-9139. 70(4), p. 1360–1376. doi: 10.1002/hep.30631.
• Fuglerud, Bettina Maria; Ledsaak, Marit; Rogne, Marie; Eskeland, Ragnhild & Gabrielsen, Odd Stokke (2018). The pioneer factor activity of c-Myb involves recruitment of p300 and induction of histone acetylation followed by acetylation-induced chromatin dissociation. Epigenetics & Chromatin. ISSN 1756-8935. 11(1). doi: 10.1186/s13072-018-0208-y. Full text in Research Archive
• Fuglerud, Bettina Maria; Lemma, Roza Berhanu; Wanichawan, Pimthanya; Sundaram, Arvind; Eskeland, Ragnhild & Gabrielsen, Odd Stokke (2017). A c-Myb mutant causes deregulated differentiation due to impaired histone binding and abrogated pioneer factor function. Nucleic Acids Research (NAR). ISSN 0305-1048. 45(13), p. 7681–7696. doi: 10.1093/nar/gkx364. Full text in Research Archive
• Ledsaak, Marit; Bengtsen, Mads; Molværsmyr, Ann-Kristin; Fuglerud, Bettina Maria; Matre, Vilborg & Eskeland, Ragnhild [Show all 7 contributors for this article] (2016). PIAS1 binds p300 and behaves as a coactivator or corepressor of the transcription factor c-Myb dependent on SUMO-status. Biochimica et Biophysica Acta. Gene Regulatory Mechanisms. ISSN 1874-9399. 1859(5), p. 705–718. doi: 10.1016/j.bbagrm.2016.03.011.

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