Roza Berhanu Lemma

• Rauluseviciute, Ieva; Riudavets-Puig, Rafael; Blanc-Mathieu, Romain; Castro Mondragon, Jaime Abraham; Ferenc, Katalin Terezia & Kumar, Vipin [Vis alle 20 forfattere av denne artikkelen] (2023). JASPAR 2024: 20th anniversary of the open-access database of transcription factor binding profiles. Nucleic Acids Research (NAR). ISSN 0305-1048. 52(D1), s. D174–D182. doi: 10.1093/nar/gkad1059. Fulltekst i vitenarkiv Vis sammendrag

  JASPAR (https://jaspar.elixir.no/) is a widely-used open-access database presenting manually curated high-quality and non-redundant DNA-binding profiles for transcription factors (TFs) across taxa. In this 10th release and 20th-anniversary update, the CORE collection has expanded with 329 new profiles. We updated three existing profiles and provided orthogonal support for 72 profiles from the previous release's UNVALIDATED collection. Altogether, the JASPAR 2024 update provides a 20% increase in CORE profiles from the previous release. A trimming algorithm enhanced profiles by removing low information content flanking base pairs, which were likely uninformative (within the capacity of the PFM models) for TFBS predictions and modelling TF-DNA interactions. This release includes enhanced metadata, featuring a refined classification for plant TFs’ structural DNA-binding domains. The new JASPAR collections prompt updates to the genomic tracks of predicted TF binding sites (TFBSs) in 8 organisms, with human and mouse tracks available as native tracks in the UCSC Genome browser. All data are available through the JASPAR web interface and programmatically through its API and the updated Bioconductor and pyJASPAR packages. Finally, a new TFBS extraction tool enables users to retrieve predicted JASPAR TFBSs intersecting their genomic regions of interest.

• 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. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Clarke, Mary L.; Lemma, Roza Berhanu; Walton, David Scott; Volpe, Giacomo; Noyvert, Boris & Gabrielsen, Odd Stokke [Vis alle 7 forfattere av denne artikkelen] (2023). MYB insufficiency disrupts proteostasis in hematopoietic stem cells, leading to age-related neoplasia. Blood. ISSN 0006-4971. 141(15), s. 1858–1870. doi: 10.1182/blood.2022019138. Fulltekst i vitenarkiv Vis sammendrag

  MYB plays a key role in gene regulation throughout the hematopoietic hierarchy and is critical for the maintenance of normal hematopoietic stem cells (HSC). Acquired genetic dysregulation of MYB is involved in the etiology of a number of leukemias, although inherited noncoding variants of the MYB gene are a susceptibility factor for many hematological conditions, including myeloproliferative neoplasms (MPN). The mechanisms that connect variations in MYB levels to disease predisposition, especially concerning age dependency in disease initiation, are completely unknown. Here, we describe a model of Myb insufficiency in mice that leads to MPN, myelodysplasia, and leukemia in later life, mirroring the age profile of equivalent human diseases. We show that this age dependency is intrinsic to HSC, involving a combination of an initial defective cellular state resulting from small effects on the expression of multiple genes and a progressive accumulation of further subtle changes. Similar to previous studies showing the importance of proteostasis in HSC maintenance, we observed altered proteasomal activity and elevated proliferation indicators, followed by elevated ribosome activity in young Myb-insufficient mice. We propose that these alterations combine to cause an imbalance in proteostasis, potentially creating a cellular milieu favoring disease initiation.

• Lemma, Roza Berhanu; Fleischer, Thomas; Martinsen, Emily; Ledsaak, Marit; Kristensen, Vessela N. & Eskeland, Ragnhild [Vis alle 8 forfattere av denne artikkelen] (2022). Pioneer transcription factors are associated with the modulation of DNA methylation patterns across cancers. Epigenetics & Chromatin. ISSN 1756-8935. 15. doi: 10.1186/s13072-022-00444-9. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Clarke, Mary L.; Lemma, Roza Berhanu; Walton, David Scott; Volpe, G; Noyvert, Boris & Gabrielsen, Odd Stokke [Vis alle 7 forfattere av denne artikkelen] (2021). MYB insufficiency disrupts proteostasis in hematopoietic stem cells leading to age-related neoplasia. bioRxiv. ISSN 2692-8205. doi: 10.1101/2021.09.04.458970.
• Castro Mondragon, Jaime Abraham; Riudavets Puig, Rafael; Rauluseviciute, Ieva; Lemma, Roza Berhanu; Turchi, Laura & Blanc-Mathieu, Romain [Vis alle 23 forfattere av denne artikkelen] (2021). JASPAR 2022: the 9th release of the open-acess database of transcription factor binding profiles. Nucleic Acids Research (NAR). ISSN 0305-1048. doi: 10.1093/nar/gkab1113. Fulltekst i vitenarkiv
• 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. Fulltekst i vitenarkiv Vis sammendrag

  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

• Fan, Qiong; Nørgaard, Rikke Christine; Grytten, Ivar; Ness, Cecilie; Lucas, Christin & Vekterud, Kristin [Vis alle 15 forfattere av denne artikkelen] (2020). LXRα Regulates ChREBPα Transactivity in a Target Gene-Specific Manner through an Agonist-Modulated LBD-LID Interaction. Cells. ISSN 2073-4409. 9(5), s. 1–26. doi: 10.3390/cells9051214. Fulltekst i vitenarkiv Vis sammendrag

  The cholesterol-sensing nuclear receptor liver X receptor (LXR) and the glucose-sensing transcription factor carbohydrate responsive element-binding protein (ChREBP) are central players in regulating glucose and lipid metabolism in the liver. More knowledge of their mechanistic interplay is needed to understand their role in pathological conditions like fatty liver disease and insulin resistance. In the current study, LXR and ChREBP co-occupancy was examined by analyzing ChIP-seq datasets from mice livers. LXR and ChREBP interaction was determined by Co-immunoprecipitation (CoIP) and their transactivity was assessed by real-time quantitative polymerase chain reaction (qPCR) of target genes and gene reporter assays. Chromatin binding capacity was determined by ChIP-qPCR assays. Our data show that LXRα and ChREBPα interact physically and show a high co-occupancy at regulatory regions in the mouse genome. LXRα co-activates ChREBPα and regulates ChREBP-specific target genes in vitro and in vivo. This co-activation is dependent on functional recognition elements for ChREBP but not for LXR, indicating that ChREBPα recruits LXRα to chromatin in trans. The two factors interact via their key activation domains; the low glucose inhibitory domain (LID) of ChREBPα and the ligand-binding domain (LBD) of LXRα. While unliganded LXRα co-activates ChREBPα, ligand-bound LXRα surprisingly represses ChREBPα activity on ChREBP-specific target genes. Mechanistically, this is due to a destabilized LXRα:ChREBPα interaction, leading to reduced ChREBP-binding to chromatin and restricted activation of glycolytic and lipogenic target genes. This ligand-driven molecular switch highlights an unappreciated role of LXRα in responding to nutritional cues that was overlooked due to LXR lipogenesis-promoting function.

• Fan, Qiong; Nørgaard, Rikke Christine; Grytten, Ivar; Ness, Cecilie Maria; Lucas, Christin & Vekterud, Kristin [Vis alle 15 forfattere av denne artikkelen] (2019). Open the LID: LXRα regulates ChREBPα transactivity in a target gene-specific manner through an agonist-modulated LBD-LID interaction. bioRxiv. ISSN 2692-8205. doi: 10.1101/2019.12.20.869974. Vis sammendrag

  The cholesterol-sensing nuclear receptor liver X receptor (LXR) and the glucose-sensing transcription factor carbohydrate responsive element-binding protein (ChREBP) are central players in regulating glucose and lipid metabolism in liver. We have previously shown that LXR regulates ChREBP transcription and activity; however, the underlying mechanisms are unclear. In the current study, we demonstrate that LXRα and ChREBPα interact physically, and show a high co-occupancy at regulatory regions in the mouse genome. LXRα co-activates ChREBPα, and regulates ChREBP-specific target genes in vitro and in vivo. This co-activation is dependent on functional recognition elements for ChREBP, but not for LXR, indicating that ChREBPα recruits LXRα to chromatin in trans. The two factors interact via their key activation domains; ChREBPα’s low glucose inhibitory domain (LID) and the ligand-binding domain (LBD) of LXRα. While unliganded LXRα co-activates ChREBPα, ligand-bound LXRα surprisingly represses ChREBPα activity on ChREBP-specific target genes. Mechanistically, this is due to a destabilized LXRα:ChREBPα interaction, leading to reduced ChREBP-binding to chromatin and restricted activation of glycolytic and lipogenic target genes. This ligand-driven molecular switch highlights an unappreciated role of LXRα that was overlooked due to LXR lipogenesis-promoting function.

• Rodriguez- Castañeda, Fernando; Lemma, Roza Berhanu; Cuervo Torre, Ignacio; Bengtsen, Mads; Moen, Lisa Marie & Ledsaak, Marit [Vis alle 8 forfattere av denne artikkelen] (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), s. 15439–15454. doi: 10.1074/jbc.RA118.002844. Fulltekst i vitenarkiv Vis sammendrag

  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; 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), s. 7681–7696. doi: 10.1093/nar/gkx364. Fulltekst i vitenarkiv

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• Lemma, Roza Berhanu (2022). Pioneer transcription factors are associated with the modulation of DNA methylation patterns across cancers (NBD2022). Vis sammendrag

  Epigenetics marks such as chromatin and DNA modifications act as molecular stamps defining active or inactive regulatory states that are crucial for proper homeostasis and development. These marks can be recognized and read by epigenetic readers such as transcription factors (TFs), thereby influencing transcription. Among the various DNA modifications, 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 understand the underlying molecular mechanism driving this process, we hypothesized that aberrant methylation patterns could be regulated by the binding of specific TFs across cancer types. We combined DNA methylation arrays and gene expression data from The Cancer Genome Atlas (TCGA) with high quality TF binding sites (TFBSs) from the UniBind database (version 2018) to explore the interplay between TF binding and DNA methylation in 19 cancer types. Using these combined data, we performed emQTL (expression-methylation quantitative trait loci) analyses in each cancer type independently (See Figure 1A for short overview of the emQTL analysis workflow and Figure 1B for fraction of correlated CpGs per 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. These 13 TFs, which we referred to as emTFs (expression methylation 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 previously reported in protecting DNA from de novo DNA methylation. Among our predicted emTFs, many were in agreement with other predictions including a recent back-to-back paper by Detilleux et al. We observed modulation of DNA methylation associated with TF binding at cis-regulatory regions controlling immune- and cancer-associated pathways, indicating 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.

• Nederbragt, Lex; Lemma, Roza Berhanu; Belova, Tatiana; Cheneby, Jeanne; Ibrahim, Mohamed & Akdeniz, Byram Cevdet [Vis alle 7 forfattere av denne artikkelen] (2022). Oslo Bioinformatics Workshop Week 2022. Vis sammendrag

  December 7th-13th 2022 will see the very first Oslo Bioinformatics Workshop Week at the University of Oslo, Norway. This event is organised by the Student Committee of the Centre for Bioinformatics at UiO, in collaboration with the ISCB Regional Student group in Norway. These workshops are open to the scientific community in Oslo and the surrounding area.

• Kumar, Vipin; Fatima, Nazeefa; Hsieh, Ping-Han; Belova, Tatiana; Ferenc, Katalin Terezia & Rauluseviciute, Ieva [Vis alle 9 forfattere av denne artikkelen] (2022). Introducing ISCB's (International Society for Computational Biology) regional student group in Norway's (RSG-Norway's) activities to the PhD and postdoc forum at the Institute of Cancer research, Radium hospital, OUS .
• Fatima, Nazeefa; Lemma, Roza Berhanu; Rauluseviciute, Ieva; Belova, Tatiana; Kumar, Vipin & Hsieh, Ping-Han [Vis alle 12 forfattere av denne artikkelen] (2022). Developing Bioinformatics Societies in Norway and Nordic. Vis sammendrag

  With the increasing amount of biological data, the need for computational skills has become prominent. Interdisciplinary fields such as computational biology require interdisciplinary collaborations; in order to create an environment for sharing skills and experiences, opportunities for funding and training, career path advice, and research ideas. Creating such environments also help to establish an inclusive platform where students and early-career researchers in computational biology can socialise and help each other in an informal setting. Currently, this is achieved locally at department level at a university or industrial company. The social interactions between students and established scientists are, therefore, consequently limited to the geographical locations of their institutions. The Regional Study Group Norway (RSG-Norway), part of the International Society of Computational Biology (ISCB), aims to create a country-wide platform, to bring together aspiring and established bioinformaticians and to develop an active presence in the Norwegian bioinformatics community. Regional level communities such as RSG-Norway are particularly helpful for students to broaden training and career opportunities. It can also help foreign researchers and students, in settling as new arrivals, through building contacts with those who are familiar with studying and working in Norway. Finally, the study group can be a channel for students and trainees to initiate and/or realise their own ideas regarding social and professional communication with fellow bioinformaticians. RSG-Norway works together with Nordic Computational Biology (NCB), which serves as a resource and knowledge-exchange hub to bring together people from industries and academia as well as local communities such as Regional Student Groups across the Nordics. As part of the NCB, Nordic RSGs are able to build cross-border collaborations and organise open events that reach a wider audience strengthening the community's knowledge-base. The presentation for this abstract will include information on past events and initiatives by RSG-Norway and NCB, their future activities and plans, and how to get involved as a member and an advisor to help develop the computational biology community in Norway and the Nordics.

• Lemma, Roza Berhanu; Castro-Mondragon, Jaime Abraham & Mathelier, Anthony (2022). Large-scale investigation of noncoding elements associated with transcriptional deregulation involved in carcinogenesis.
• Lemma, Roza Berhanu (2022). Pioneer transcription factors are associated with the modulation of DNA methylation patterns across cancers. Vis sammendrag

  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.

• Fan, Qiong; Nørgaard, Rikke Christine; Grytten, Ivar; Ness, Cecilie Maria; Lucas, Christin & Vekterud, Kristin [Vis alle 15 forfattere av denne artikkelen] (2019). LXRα interacts with the glucose-sensing transcription factor ChREBPα to regulate its transcriptional activity. Vis sammendrag

  The cholesterol-sensing nuclear receptor Liver X Receptor (LXR) and the glucose-sensing transcription factor carbohydrate responsive element-binding protein (ChREBP) are central players in the regulation of glucose and lipid metabolism. LXR does this job in part by regulating the expression of ChREBP. We have previously shown that LXR also regulates ChREBP activity. To get a better understanding of mechanisms at play, we asked if LXR and ChREBP interact physically. Interestingly, LXRα binds to ChREBPα, but not the shorter isoform ChREBPβ. Co-immunoprecipitation (CoIP) of different LXR and ChRBEP domains shows that it is ChREBPα’s low glucose inhibitory domain (LID), which is lacking in ChREBPβ, that interacts with the ligand-binding domain (LBD) of LXRα. In line with this, we see a surprisingly high co-occupancy of LXR and ChREBP on regulatory regions in the mouse genome when re-analysing two independently published chromatin immunoprecipitation-sequencing (ChIP-seq) datasets. Moreover, Functional studies show that LXRα is able to co-activate together with ChREBPα, but not ChREBPβ, and increase ChREBP-specific target gene expression in vitro and in vivo. Unexpectedly however, ligand-engaged LXR exhibits a repressive effect on the expression of the same genes in primary mouse hepatocytes, in contrast to what we observe with target genes that are common to LXR and ChREBP. Performing CoIP and ChIP on selected target genes, we demonstrate mechanistically that the repressive effect most likely is due to a weakened ChREBPα:LXRα interaction and reduced binding of ChREBP to chromatin. Altogether, the novel transcriptional complex comprising ChREBPα and LXRα adds to the intricate integration of nutrient signals in glucose and lipid metabolism.

• Fan, Qiong; Nørgaard, Rikke Christine; Grytten, Ivar; Ulven, Stine Marie; Lucas, Christin & Bindesbøll, Christian [Vis alle 11 forfattere av denne artikkelen] (2018). LXRα interacts with the glucose-sensing transcription factor ChREBPα and increases its transcriptional activity.

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