Ragnhild Eskeland

• Nguyen, Xuan Thang; Martiensen, Emily Louise Beecher; Abdelhalim, Mohamed; Tran, Trung; Ledsaak, Marit & Rogne, Marie [Show all 8 contributors for this article] (2026). Proteome-wide multi-omics profiling of osteosarcoma transcription factor networks. bioRxiv (preprint article). doi: 10.64898/2026.03.29.714917. Full text in Research Archive Show summary

  Osteosarcoma (OS) is an aggressive bone cancer that most commonly affects children and young adults. OS exhibits a high degree of genomic complexity, as well as cellular plasticity, and dynamic transcriptional regulation is suggested to contribute to treatment resistance and metastasis. Cell lines are well characterized as models to advance our knowledge on OS biology. HOS and U2OS cells have increased invasiveness and higher migratory ability compared with MG63. In this study, we employed a tandem array of consensus transcription factor response elements (catTFREs) proteomic approach to characterize transcription factor (TF) regulatory networks related to OS aggressiveness. We mapped 7,594 proteins and enriched 352 transcription factors and coregulators. When we integrated proteomics with cell line specific gene expression and chromatin accessibility we classified the proteins into different OS cell line dependent sub-clusters and identified TFs and coregulators common for all cell lines and specific for individual cell lines. We demonstrate that RUNX2, MYBL2 and HMGA2 are specifically enriched in HOS and U2OS and may be linked to the cell aggressiveness. ETV5, JUNB, NFIX and ZEB1 were among TFs specific to MG63. Our analysis provides a more comprehensive understanding of the transcriptional drivers that shape OS regulatory landscapes and may have future therapeutic implications.

• Rossini, Roberto; Oshaghi, Mohammadsaleh; Nekrasov, Maxim; Bellanger, Aurélie Nathalie Pascale; Domaschenz, Renae & Dijkwel, Yasmin [Show all 13 contributors for this article] (2025). Loss of multilevel 3D genome organization during breast cancer progression. Genome Research. ISSN 1088-9051. p. 1–18. doi: 10.1101/gr.280791.125. Full text in Research Archive Show summary

  Breast cancer entails intricate alterations in genome organization and expression. However, how three-dimensional (3D) chromatin structure changes in the progression from a normal to a breast cancer malignant state remains unknown. To address this, we have conducted an analysis combining Hi-C data with lamina-associated domains (LADs), epigenomic marks, and gene expression in an in vitro model of breast cancer progression. Our results reveal that although the fundamental properties of topologically associating domains (TADs) are overall maintained, significant changes occur in the organization of compartments and subcompartments. These changes are closely correlated with alterations in the expression of oncogenic genes. We also observe a restructuring of TAD–TAD interactions, coinciding with a loss of spatial compartmentalization and radial positioning of the 3D genome. Notably, we identify a previously unrecognized interchromosomal insertion event, wherein a locus on Chromosome 8 housing the MYC oncogene is inserted into a highly active subcompartment on Chromosome 10. This insertion is accompanied by the formation of de novo enhancer contacts and activation of MYC , illustrating how structural genomic variants can alter the 3D genome during oncogenesis. In summary, our findings provide evidence for the loss of genome organization at multiple scales during breast cancer progression, revealing novel relationships between genome 3D structure and oncogenic processes.

• Fosslie, Madeleine Lystad; Ilaslan, Erkut; Skuland, Trine; Choudalakis, Michel; Søegaard, Mirra Louise Cicilie & Halliwell, Jason Alexander [Show all 23 contributors for this article] (2025). Major waves of H2A.Z incorporation during mouse oogenesis and preimplantation embryo development. Nature Communications. 17(1). doi: 10.1038/s41467-025-66919-x. Full text in Research Archive Show summary

  Abstract Epigenomes of mammalian oocytes and embryos undergo major transitions essential for successful development. Here, we provide genome-wide maps of histone variant H2A.Z during twelve stages of mouse oogenesis and preimplantation embryo development and relate it to histone marks and genomic features. This revealed that major waves of H2A.Z incorporation occur early in growing oocytes, forming distinct patterns of maternal, embryonic, and persistent H2A.Z enrichment. Late maternal enrichment is inherited by the zygote and precedes reduced formation of lamina associated domains and early replication in the maternal genome of 2-cell embryos. Persistent H2A.Z enrichment is strongly associated with CpG islands and H3K4me3 near transcription start sites of active genes, but thousands of maternal and embryonic H2A.Z incorporation sites exist elsewhere, frequently at transposable elements. The persisting H2A.Z enrichments across related developmental stages enable preservation of epigenetic information despite major concurrent changes in H3K4me3, H3K27me3, and DNA methylation. Altogether, this advances our understanding of how histone variants contribute to epigenetic reprogramming during mammalian oogenesis and early development.

• Lemma, Roza Berhanu; Ledsaak, Marit; Fuglerud, Bettina Maria; Castañeda, Fernando Rodriguez-; 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.

• Spildrejorde, Mari; Samara, Athina; Sharma, Ankush; Leithaug, Magnus; Falck, Martin Bengt Alfred & Modafferi, Stefania [Show all 12 contributors for this article] (2023). Multi-omics approach reveals dysregulated genes during hESCs neuronal differentiation exposure to paracetamol. iScience. 26:107755(10), p. 1–29. doi: 10.1016/j.isci.2023.107755. Full text in Research Archive Show summary

  Prenatal paracetamol exposure has been associated with neurodevelopmental outcomes in childhood. Pharmacoepigenetic studies show differences in cord blood DNA methylation between unexposed and paracetamol-exposed neonates, however, causality and impact of long-term prenatal paracetamol exposure on brain development remain unclear. Using a multi-omics approach, we investigated the effects of paracetamol on an in vitro model of early human neurodevelopment. We exposed human embryonic stem cells undergoing neuronal differentiation with paracetamol concentrations corresponding to maternal therapeutic doses. Single-cell RNA-seq and ATAC-seq integration identified paracetamol-induced chromatin opening changes linked to gene expression. Differentially methylated and/or expressed genes were involved in neurotransmission and cell fate determination trajectories. Some genes involved in neuronal injury and development-specific pathways, such as KCNE3, overlapped with differentially methylated genes previously identified in cord blood associated with prenatal paracetamol exposure. Our data suggest that paracetamol may play a causal role in impaired neurodevelopment.

• Wæhler, Hallvard Austin; Labba, Nils-Anders Johannes; Paulsen, Ragnhild Elisabeth Heimtun; Sandve, Geir Kjetil Ferkingstad & Eskeland, Ragnhild (2023). ANDA: an open-source tool for automated image analysis of in vitro neuronal cells. BMC Neuroscience. 24(1), p. 1–11. doi: 10.1186/s12868-023-00826-z. Full text in Research Archive Show summary

  Background Imaging of in vitro neuronal differentiation and measurements of cell morphologies have led to novel insights into neuronal development. Live-cell imaging techniques and large datasets of images have increased the demand for automated pipelines for quantitative analysis of neuronal morphological metrics. Results ANDA is an analysis workflow that quantifies various aspects of neuronal morphology from high-throughput live-cell imaging screens of in vitro neuronal cell types. This tool automates the analysis of neuronal cell numbers, neurite lengths and neurite attachment points. We used chicken, rat, mouse, and human in vitro models for neuronal differentiation and have demonstrated the accuracy, versatility, and efficiency of the tool. Conclusions ANDA is an open-source tool that is easy to use and capable of automated processing from time-course measurements of neuronal cells. The strength of this pipeline is the capability to analyse high-throughput imaging screens.

• Labba, Nils-Anders Johannes; Wæhler, Hallvard Austin; Houdaifi, Nora; Zosen, Denis; Haugen, Fred & Paulsen, Ragnhild Elisabeth Heimtun [Show all 8 contributors for this article] (2022). Paracetamol perturbs neuronal arborization and disrupts the cytoskeletal proteins SPTBN1 and TUBB3 in both human and chicken in vitro models. Toxicology and Applied Pharmacology. ISSN 0041-008X. 449. doi: 10.1016/j.taap.2022.116130. Full text in Research Archive Show summary

  Epidemiological studies have linked long-term/high-dose usage of paracetamol (N-acetyl-para-aminophenol, APAP) during pregnancy to adverse neuropsychiatric outcomes, primarily attention-deficit hyperactive disorder (ADHD), in the offspring. Though variable, ADHD has been associated with phenotypic alterations characterized by reductions in grey matter densities and aberrations in structural connectivity, effects which are thought to originate in neurodevelopment. We used embryonic chicken cerebellar granule neurons (CGNs) and neuronally differentiating human NTERA2 cells (NT2Ns) to investigate the in vitro effects of APAP on cell viability, migration, neuritogenesis, and the intracellular levels of various proteins involved in neurodevelopment as well as in the maintenance of the structure and function of neurites. Exposure to APAP ranging from 100 to 1600 μM yielded concentration- and time-dependent reductions in cell viability and levels of neurite arborization, as well as reductions in the levels of the cytoskeletal protein β2-spectrin, with the highest APAP concentration resulting in between 50 and 75% reductions in the aforementioned metrics over the course of 72 h. Exposure to APAP also reduced migration in the NT2Ns but not CGNs. Moreover, we found concentration- and time-dependent increases in punctate aggregation of the cytoskeletal protein β3-tubulin following exposure to APAP in both cell model systems, with the highest APAP concentration approximately doubling the number of aggregates over 72–120 h. Our findings demonstrate that APAP negatively perturbs neurite arborization degree, with concurrent reductions in the protein levels of β2-spectrin and disruption of the integrity of β3-tubulin, both proteins of which play important roles in neuronal structure and function.

• Samara, Athina; Spildrejorde, Mari; Sharma, Ankush; Falck, Martin; Leithaug, Magnus & Modafferi, Stefania [Show all 11 contributors for this article] (2022). A multi-omics approach to visualize early neuronal differentiation from hESCs in 4D. iScience. 25(11). doi: 10.1016/j.isci.2022.105279. Full text in Research Archive Show summary

  Neuronal differentiation of pluripotent stem cells is an established method to study physiology, disease, and medication safety. However, the sequence of events in human neuronal differentiation and the ability of in vitro models to recapitulate early brain development are poorly understood. We developed a protocol optimized for the study of early human brain development and neuropharmacological applications. We comprehensively characterized gene expression and epigenetic profiles at four timepoints, because the cells differentiate from embryonic stem cells towards a heterogeneous population of progenitors, immature and mature neurons bearing telencephalic signatures. A multi-omics roadmap of neuronal differentiation, combined with searchable interactive gene analysis tools, allows for extensive exploration of early neuronal development and the effect of medications.

• Lemma, Roza Berhanu; Fleischer, Thomas; Martinsen, Emily; Ledsaak, Marit; Kristensen, Vessela N. & Eskeland, Ragnhild [Show all 8 contributors for this article] (2022). Pioneer transcription factors are associated with the modulation of DNA methylation patterns across cancers. Epigenetics & Chromatin. 15. doi: 10.1186/s13072-022-00444-9. Full text in Research Archive Show summary

  Methylation of cytosines on DNA is a prominent modification associated with gene expression regulation. Aberrant DNA methylation patterns have recurrently been linked to dysregulation of the regulatory program in cancer cells. To shed light on the underlying molecular mechanism driving this process, we hypothesised that aberrant methylation patterns could be controlled by the binding of specific transcription factors (TFs) across cancer types. By combining DNA methylation arrays and gene expression data with TF binding sites (TFBSs), we explored the interplay between TF binding and DNA methylation in 19 cancer types. We performed emQTL (expression–methylation quantitative trait loci) analyses independently in each cancer type and identified 13 TFs whose expression levels are correlated with local DNA methylation patterns around their binding sites in at least 2 cancer types. The 13 TFs are mainly associated with local demethylation and are enriched for pioneer function, suggesting a specific role for these TFs in modulating chromatin structure and transcription in cancer patients. Furthermore, we confirmed that de novo methylation is precluded across cancers at CpGs lying in genomic regions enriched for TF binding signatures associated with SP1, CTCF, NRF1, GABPA, KLF9, and/or YY1. The modulation of DNA methylation associated with TF binding was observed at cis-regulatory regions controlling immune- and cancer-associated pathways, corroborating that the emQTL signals were derived from both cancer and tumor-infiltrating cells. As a case example, we experimentally confirmed that FOXA1 knock-down is associated with higher methylation in regions bound by FOXA1 in breast cancer MCF-7 cells. Finally, we reported physical interactions between FOXA1 with TET1 and TET2 both in an in vitro setup and in vivo at physiological levels in MCF-7 cells, adding further support for FOXA1 attracting TET1 and TET2 to induce local demethylation in cancer cells.

• Sharma, Ankush; Akshay, Akshay; Rogne, Marie & Eskeland, Ragnhild (2021). ShinyArchR.UiO: user-friendly,integrative and open-source tool for visualization of single-cell ATAC-seq data using ArchR. Bioinformatics. ISSN 1367-4803. 38(3), p. 834–836. doi: 10.1093/bioinformatics/btab680. Full text in Research Archive Show summary

  Motivation: Mapping of chromatin accessibility landscapes in single-cells and the integration with gene expression enables a better understanding of gene regulatory mechanisms defining cell identities and cell-fate determination in development and disease. Generally, raw data generated from single-cell Assay for Transposase-Accessible Chromatin sequencing (scATAC-seq) are deposited in repositories that are generally inaccessible due to lack of in-depth knowledge of computational programming. Results: We have developed ShinyArchR.UiO, an R-based shiny app, that facilitates scATAC-seq data accessibility and visualisation in a user-friendly, interactive, and open-source web interface. ShinyArchR.UiO is an application that can streamline collaborative efforts for interpretation of massive chromatin accessibility datasets and allow for open access data sharing for wider audiences.

• 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. 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

• Castañeda, Fernando Rodriguez-; Lemma, Roza Berhanu; Torre, Ignacio Cuervo; Bengtsen, Mads; Moen, Lisa Marie & Ledsaak, Marit [Show all 8 contributors for this article] (2018). The SUMO protease SENP1 and the chromatin remodeller CHD3 interact and jointly affect chromatin accessibility and gene expression. Journal of Biological Chemistry. ISSN 0021-9258. 293(40), p. 15439–15454. doi: 10.1074/jbc.RA118.002844. Full text in Research Archive Show summary

  The small ubiquitin-like modifier (SUMO) post-translationally modifies lysine residues of transcription factors and co-regulators and thereby contributes to an important layer of control of the activities of these transcriptional regulators. Likewise, deSUMOylation of these factors by the sentrin-specific proteases (SENPs) also plays a role in gene regulation, but whether SENPs functionally interact with other regulatory factors that control gene expression is unclear. In the present work, we focused on SENP1, specifically, on its role in activation of gene expression investigated through analysis of the SENP1 interactome, which revealed that SENP1 physically interacts with the chromatin remodeler chromodomain helicase DNA-binding protein 3 (CHD3). Using several additional methods, including GST pull-down and co-immunoprecipitation assays, we validated and mapped this interaction, and using CRISPR-Cas9–generated CHD3- and SENP1-KO cells (in the haploid HAP1 cell line), we investigated whether these two proteins are functionally linked in regulating chromatin remodeling and gene expression. Genome-wide ATAC-Seq analysis of the CHD3- and SENP1-KO cells revealed a large degree of overlap in differential chromatin openness between these two mutant cell lines. Moreover, motif analysis and comparison with ChIP-Seq profiles in K562 cells pointed to an association of CHD3 and SENP1 with CCCTC-binding factor (CTCF) and SUMOylated chromatin–associated factors. Lastly, genome-wide RNA-Seq also indicated that these two proteins co-regulate the expression of several genes. We propose that the functional link between chromatin remodeling by CHD3 and deSUMOylation by SENP1 uncovered here provides another level of control of gene expression.

• 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. 11(1). doi: 10.1186/s13072-018-0208-y. Full text in Research Archive Show summary

  Background The concept of pioneer transcription factors is emerging as an essential part of the epigenetic regulation, taking place during cell development and differentiation. However, the precise molecular mechanism underlying pioneer factor activity remains poorly understood. We recently reported that the transcription factor c-Myb acts as a pioneer factor in haematopoiesis, and a point mutation in its DNA binding domain, D152V, is able to abrogate this function. Results Here, we show that specific histone modifications, including H3K27ac, prevent binding of c-Myb to histone tails, representing a novel effect of histone modifications, namely restricting binding of a pioneer factor to chromatin. Furthermore, we have taken advantage of the pioneer-defect D152V mutant to investigate mechanisms of c-Myb’s pioneer factor activity. We show that c-Myb-dependent transcriptional activation of a gene in inaccessible chromatin relies on c-Myb binding to histones, as well as on c-Myb interacting with the histone acetyltransferase p300. ChIP assays show that both wild type and the D152V mutant of c-Myb bind to a selected target gene at its promoter and enhancer, but only wild-type c-Myb causes opening and activation of the locus. Enhancement of histone acetylation restores activation of the same gene in the absence of c-Myb, suggesting that facilitating histone acetylation is a crucial part of the pioneer factor function of c-Myb. Conclusions We suggest a pioneer factor model in which c-Myb binds to regions of closed chromatin and then recruits histone acetyltransferases. By binding to histones, c-Myb facilitates histone acetylation, acting as a cofactor for p300 at c-Myb bound sites. The resulting H3K27ac leads to chromatin opening and detachment of c-Myb from the acetylated chromatin. We propose that the latter phenomenon, acetylation-induced chromatin dissociation, represents a mechanism for controlling the dynamics of pioneer factor binding to chromatin.

• Gervin, Kristina; Nordeng, Hedvig Marie Egeland; Eskeland, Ragnhild; Paulsen, Ragnhild Elisabeth & Lyle, Robert (2017). Farmakoepigenetikk: Samspillet mellom legemidler og epigenetikk. Norsk Farmaceutisk Tidsskrift (NFT). ISSN 0029-1935. 125(8), p. 30–34. Full text in Research Archive Show summary

  Epigenetikk er læren om arvelige mekanismer som regulerer aktiviteten til genene i ulike celler og vev som ikke involverer en endring i selve DNA-sekvensen. Om gener er skrudd av eller på er bestemt av epigenetiske merkelapper festet til det enkelte genet. Hensikten med denne artikkelen er å gi en kortfattet introduksjon til epigenetikk og farmakoepigenetikk. Epigenetiske faktorer antas å være viktige i utviklingen av en rekke sykdommer, som visse kreftformer og utviklingsforstyrrelser i nervesystemet. Det finnes allerede legemidler på markedet som virker via epigenetiske mekanismer ved å påvirke det epigenetiske maskineriet som fester de epigenetiske merkelappene til DNA-et, eller proteiner som DNA-et er kveilet rundt. Spesielt innen kreftmedisin satses det stort på utvikling av legemidler som kan normalisere avvikende genuttrykk via epigenetiske mekanismer. Lite er kjent om legemidler kan gi opphav til bivirkninger via epigenetiske mekanismer.

• Fleischer, Thomas; Tekpli, Xavier; Mathelier, Anthony; Wang, Shixiong; Nebdal, Daniel J.H. & Dhakal, Hari Prasad [Show all 16 contributors for this article] (2017). DNA methylation at enhancers identifies distinct breast cancer lineages. Nature Communications. 8(1379). doi: 10.1038/s41467-017-00510-x. Full text in Research Archive Show summary

  Breast cancers exhibit genome-wide aberrant DNA methylation patterns. To investigate how these affect the transcriptome and which changes are linked to transformation or progression, we apply genome-wide expression–methylation quantitative trait loci (emQTL) analysis between DNA methylation and gene expression. On a whole genome scale, in cis and in trans, DNA methylation and gene expression have remarkably and reproducibly conserved patterns of association in three breast cancer cohorts (n = 104, n = 253 and n = 277). The expression–methylation quantitative trait loci associations form two main clusters; one relates to tumor infiltrating immune cell signatures and the other to estrogen receptor signaling. In the estrogen related cluster, using ChromHMM segmentation and transcription factor chromatin immunoprecipitation sequencing data, we identify transcriptional networks regulated in a cell lineage-specific manner by DNA methylation at enhancers. These networks are strongly dominated by ERα, FOXA1 or GATA3 and their targets were functionally validated using knockdown by small interfering RNA or GRO-seq analysis after transcriptional stimulation with estrogen.

• Simovski, Boris; Vodak, Daniel; Gundersen, Sveinung; Domanska, Diana Ewa; Azab, Abdulrahman & Holden, Lars [Show all 25 contributors for this article] (2017). GSuite HyperBrowser: integrative analysis of dataset collections across the genome and epigenome. GigaScience. 6(7), p. 1–12. doi: 10.1093/gigascience/gix032. Full text in Research Archive Show summary

  Background: Recent large-scale undertakings such as ENCODE and Roadmap Epigenomics have generated experimental data mapped to the human reference genome (as genomic tracks) representing a variety of functional elements across a large number of cell types. Despite the high potential value of these publicly available data for a broad variety of investigations, little attention has been given to the analytical methodology necessary for their widespread utilisation. Findings: We here present a first principled treatment of the analysis of collections of genomic tracks. We have developed novel computational and statistical methodology to permit comparative and confirmatory analyses across multiple and disparate data sources. We delineate a set of generic questions that are useful across a broad range of investigations and discuss the implications of choosing different statistical measures and null models. Examples include contrasting analyses across different tissues or diseases. The methodology has been implemented in a comprehensive open-source software system, the GSuite HyperBrowser. To make the functionality accessible to biologists, and to facilitate reproducible analysis, we have also developed a web-based interface providing an expertly guided and customizable way of utilizing the methodology. With this system, many novel biological questions can flexibly be posed and rapidly answered. Conclusions: Through a combination of streamlined data acquisition, interoperable representation of dataset collections and customizable statistical analysis with guided setup and interpretation, the GSuite HyperBrowser represents a first comprehensive solution for integrative analysis of track collections across the genome and epigenome. The software is available at: https://hyperbrowser.uio.no

• 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 Show summary

  The transcription factor c-Myb is involved in early differentiation and proliferation of haematopoietic cells, where it operates as a regulator of self-renewal and multi-lineage differentiation. Deregulated c-Myb plays critical roles in leukaemias and other human cancers. Due to its role as a master regulator, we hypothesized it might function as a pioneer transcription factor. Our approach to test this was to analyse a mutant of c-Myb, D152V, previously reported to cause haematopoietic defects in mice by an unknown mechanism. Our transcriptome data from K562 cells indicates that this mutation specifically affects c-Myb's ability to regulate genes involved in differentiation, causing failure in c-Myb's ability to block differentiation. Furthermore, we see a major effect of this mutation in assays where chromatin opening is involved. We show that each repeat in the minimal DNA-binding domain of c-Myb binds to histones and that D152V disrupts histone binding of the third repeat. ATAC-seq data indicates this mutation impairs the ability of c-Myb to cause chromatin opening at specific sites. Taken together, our findings support that c-Myb acts as a pioneer factor and show that D152V impairs this function. The D152V mutant is the first mutant of a transcription factor specifically destroying pioneer factor function.

• Maclennan, Marie; García-Cañadas, Marta; Reichmann, Judith; Khazina, Elena; Wagner, Gabriele & Playfoot, Christopher J. [Show all 18 contributors for this article] (2017). Mobilization of LINE-1 retrotransposons is restricted by Tex19.1 in mouse embryonic stem cells. eLIFE. 6:e26152, p. 1–32. doi: 10.7554/eLife.26152. Full text in Research Archive Show summary

  Mobilization of retrotransposons to new genomic locations is a significant driver of mammalian genome evolution, but these mutagenic events can also cause genetic disorders. In humans, retrotransposon mobilization is mediated primarily by proteins encoded by LINE-1 (L1) retrotransposons, which mobilize in pluripotent cells early in development. Here we show that TEX19.1, which is induced by developmentally programmed DNA hypomethylation, can directly interact with the L1-encoded protein L1-ORF1p, stimulate its polyubiquitylation and degradation, and restrict L1 mobilization. We also show that TEX19.1 likely acts, at least in part, through promoting the activity of the E3 ubiquitin ligase UBR2 towards L1-ORF1p. Moreover, loss of Tex19.1 increases L1-ORF1p levels and L1 mobilization in pluripotent mouse embryonic stem cells, implying that Tex19.1 prevents de novo retrotransposition in the pluripotent phase of the germline cycle. These data show that post-translational regulation of L1 retrotransposons plays a key role in maintaining trans-generational genome stability in mammals.

• 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. Full text in Research Archive
• Ortiz, Antonio Carlos Mora; Sandve, Geir Kjetil; Gabrielsen, Odd Stokke & Eskeland, Ragnhild (2015). In the loop: promoter-enhancer interactions and bioinformatics. Briefings in Bioinformatics. ISSN 1467-5463. doi: 10.1093/bib/bbv097. Full text in Research Archive Show summary

  Enhancer–promoter regulation is a fundamental mechanism underlying differential transcriptional regulation. Spatial chromatin organization brings remote enhancers in contact with target promoters in cis to regulate gene expression. There is considerable evidence for promoter–enhancer interactions (PEIs). In the recent years, genome-wide analyses have identified signatures and mapped novel enhancers; however, being able to precisely identify their target gene(s) requires massive biological and bioinformatics efforts. In this review, we give a short overview of the chromatin landscape and transcriptional regulation. We discuss some key concepts and problems related to chromatin interaction detection technologies, and emerging knowledge from genome-wide chromatin interaction data sets. Then, we critically review different types of bioinformatics analysis methods and tools related to representation and visualization of PEI data, raw data processing and PEI prediction. Lastly, we provide specific examples of how PEIs have been used to elucidate a functional role of non-coding single-nucleotide polymorphisms. The topic is at the forefront of epigenetic research, and by highlighting some future bioinformatics challenges in the field, this review provides a comprehensive background for future PEI studies.

• Bengtsen, Mads; Klepper, Kjetil; Gundersen, Sveinung; Torre, Ignacio Cuervo; Drabløs, Finn & Hovig, Johannes Eivind [Show all 9 contributors for this article] (2015). c-Myb Binding Sites in Haematopoietic Chromatin Landscapes. PLOS ONE. 10(7). doi: 10.1371/journal.pone.0133280. Full text in Research Archive Show summary

  Strict control of tissue-specific gene expression plays a pivotal role during lineage commit- ment. The transcription factor c-Myb has an essential role in adult haematopoiesis and func- tions as an oncogene when rearranged in human cancers. Here we have exploited digital genomic footprinting analysis to obtain a global picture of c-Myb occupancy in the genome of six different haematopoietic cell-types. We have biologically validated several c-Myb foot- prints using c-Myb knockdown data, reporter assays and DamID analysis. We show that our predicted conserved c-Myb footprints are highly dependent on the haematopoietic cell type, but that there is a group of gene targets common to all cell-types analysed. Further- more, we find that c-Myb footprints co-localise with active histone mark H3K4me3 and are significantly enriched at exons. We analysed co-localisation of c-Myb footprints with 104 chromatin regulatory factors in K562 cells, and identified nine proteins that are enriched together with c-Myb footprints on genes positively regulated by c-Myb and one protein enriched on negatively regulated genes. Our data suggest that c-Myb is a transcription fac- tor with multifaceted target regulation depending on cell type.

• Lund, Eivind Gard; Ruppelt, Anja Oldenburg; Delbarre, Erwan; Freberg, Christel Taranger; Duband-Goulet, Isabelle & Eskeland, Ragnhild [Show all 8 contributors for this article] (2013). Lamin A/C-promoter interactions specify chromatin state-dependent transcription outcomes. Genome Research. ISSN 1088-9051. 23(10), p. 1580–1589. doi: 10.1101/gr.159400.113. Full text in Research Archive
• Collas, Philippe & Eskeland, Ragnhild (2013). Oslo Epigenetics Symposium 2012 Oslo, Norway, 8-9 November 2012. Epigenomics. ISSN 1750-1911. 5(1), p. 29–32. doi: 10.2217/EPI.12.76. Full text in Research Archive
• Chioda, Christina; Spada, Fabio; Eskeland, Ragnhild & Thompson, Eric (2004). Histone mRNAs do not accumulate during S phase of either mitotic or endoreduplicative cycles in the chordate Oikopleura dioica. Molecular and Cellular Biology. ISSN 0270-7306. 24(12), p. 5391–5403. Full text in Research Archive Show summary

  Metazoan histones are generally classified as replication-dependent or replacement variants. Replication-dependent histone genes contain cell cycle-responsive promoter elements, their transcripts terminate in an unpolyadenylated conserved stem-loop, and their mRNAs accumulate sharply during S phase. Replacement variant genes lack cell cycle-responsive promoter elements, their polyadenylated transcripts lack the stem-loop, and they are expressed at low levels throughout the cell cycle. During early development of some organisms with rapid cleavage cycles, replication-dependent mRNAs are not fully S phase restricted until complete cell cycle regulation is achieved. The accumulation of polyadenylated transcripts during this period has been considered incompatible with metazoan development. We show here that histone metabolism in the urochordate Oikopleura dioica does not accord with some key tenets of the replication-dependent/replacement variant paradigm. During the premetamorphic mitotic phase of development, expressed variants shared characteristics of replication-dependent histones, including the 3' stem-loop, but, in contrast, were extensively polyadenylated. After metamorphosis, when cells in many tissues enter endocycles, there was a global downregulation of histone transcript levels, with most variant transcripts processed at the stem-loop. Contrary to the 30-fold S-phase upregulation of histone transcripts described in common metazoan model organisms, we observed essentially constant histone transcript levels throughout both mitotic and endoreduplicative cell cycles.

• Chioda, Christina; Eskeland, Ragnhild & Thompson, Eric (2002). Histone gene complement, variant expression, and mRNA processing in a urochordate Oikopleura dioica that undergoes extensive polyploidization. Molecular Biology and Evolution (MBE). ISSN 0737-4038. 19, p. 2247–2260. Full text in Research Archive Show summary

  Considerable data exist on coding sequences of histones in a wide variety of organisms. Much more restricted information is available on total histone gene complement, gene organization, transcriptional regulation, and histone mRNA processing. In particular, there is a significant phylogenetic gap in information for the urochordates, a subphylum near the invertebrate-vertebrate transition. In this study, we show that the appendicularian Oikopleura dioica has a histone gene complement that is similar to that of humans, though its genome size is 40- to 50-fold smaller. At a total length of 3.5 kb, the H3, H4, H1, H2A, and H2B quintet cluster is the most compact described thus far, but despite very rapid early developmental cleavage cycles, no extensive tandem repeats of the cluster were present. The high degree of variation within each of the complements of O. dioica H2A and H2B subtypes resembled that found in plants as opposed to more closely related vertebrate and invertebrate species, and developmental stage-specific expression of different subtypes was observed. The linker histone H1 was present in relatively few copies per haploid genome and contained short N- and C-terminal tails, a feature similar to that of copepods but different from many standard model organisms. The 3'UTRs of the histone genes contained both the consensus stem-loop sequence and the polyadenylation signals but lacked the consensus histone downstream element that is involved in the processing of histone mRNAs in echinoderms and vertebrates. Two types of transcripts were found, i.e., those containing both the stem-loop and a polyA tail as well as those cleaved at the normal site just 3' of the stem-loop. The O. dioica data are an important addition to the limited number of eukaryotes for which sufficiently extensive information on histone gene complements is available. Increasingly, it appears that understanding the evolution of histone gene organization, transcriptional regulation, and mRNA processing will depend at least as much on comparative analysis of constraints imposed by certain life history features and cell biological characteristics as on projections based on simple phylogenetic relationships.

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• Marianne, Sletbakk; Arnodd, Håpnes; Hessen, Dag Olav; Kristin, Martinsen & Eskeland, Ragnhild (2022). Bios 2 Biologi 2 (LK20). Cappelen Damm Akademisk. ISBN 9788202743253. 432 p. Full text in Research Archive
• Sletbakk, Marianne; Marthinsen, Kirsten; Hessen, Dag Olav; Håpnes, Arnodd; Eskeland, Ragnhild & Spurkland, Anne (2021). Bios 1 Biologi 1 (LK20). Cappelen Damm AS. ISBN 9788202696566. Full text in Research Archive
• Sletbakk, Marianne; Håpenes, Arnodd; Hessen, Dag Olav; Eskeland, Ragnhild; Gjærevoll, Inger & Borge, Ole Johan (2019). BIOS 2. Cappelen Damm AS. ISBN 9788202604851. Full text in Research Archive

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• Eskeland, Ragnhild (2023). Stem cells and cancer single-cell transcriptional landscapes and beyond. Full text in Research Archive
• Eskeland, Ragnhild (2023). Stem cells and sarcoma single-cell landscapes and beyond. Full text in Research Archive
• Eskeland, Ragnhild (2023). Pioneering functions is abrogated by FOXA1 mutations. Full text in Research Archive
• Bochynska, Agata; Eskeland, Ragnhild; Lien, Marianne Elisabeth & Klette, Kirsti (2023). Why and how to share qualitative data. Full text in Research Archive
• Eskeland, Ragnhild (2023). På oppdagingsferd i nye cellelandskap. Full text in Research Archive
• Samara, Athina; Falck, Martin; Spildrejorde, Mari; Leithaug, Magnus; Acharya, Ganesh & Lyle, Robert [Show all 7 contributors for this article] (2022). Robust neuronal differentiation of human embryonic stem cells for neurotoxicology. STAR Protocols. 3(3). doi: 10.1016/j.xpro.2022.101533. Full text in Research Archive Show summary

  Here, we describe a protocol for rapid neuronal differentiation from human embryonic stem cells (hESCs) toward a heterogenous population of telencephalic progenitors, immature and mature neurons, for drug-screening and early-brain differentiation studies. hESC neuronal differentiation depends on adhesion and minimal cell-passaging to avert monolayer cross-connectivity rupture. In this protocol, we detail optimized cell-seeding densities and coating conditions with high cell viability suitable for neurotoxicology and high-resolution single-cell omics studies. Daily media changes reduce compound instability and degradation for optimal screening. For complete details on the use and execution of this protocol, please refer to Samara et al. (2022).

• Haraldsen, Kirsten Borse; Rogne, Sissel; Eskeland, Ragnhild; Kjeldstad, Torunn; Olsbye, Unni & Røyne, Anja (2017). Panelsamtale: Hva nå? DAMER! 100 år med kvinner i realfagene ved UiO. Full text in Research Archive Show summary

  Innledning/forberedelser til panelsamtale ledet av Sissel Rogne under åpningen av utstillingen "Damer!"

• Eskeland, Ragnhild & Grini, Paul Eivind (2015). Epigenetikk – hadde Lamarck rett? In Hessen, Dag Olav; Lie, Thore & Stenseth, Nils Christian (Ed.), Mendels arv - Genetikkens æra. Gyldendal Norsk Forlag A/S. ISSN 9788205458185. p. 182–215. Full text in Research Archive

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