| 1. |
- Dhanda, R. S., et al.
(author)
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The human SIN3B corepressor forms a nucleolar complex with leukemia-associated ETO homologues
- 2008
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In: BMC Molecular Biology. - : Springer Science and Business Media LLC. - 1471-2199. ; 9, s. 1-17
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Journal article (peer-reviewed)abstract
- Background: SIN3 ( SWI-Independent) is part of a transcriptional deacetylase complex, which generally mediates the formation of repressive chromatin. The purpose of this work was to study possible interactions between corepressors human SIN3B (hSIN3B) and the ETO homologues ETO ( eight twenty-one), MTG16 ( myeloid-transforming gene 16) and MTGR1 ( MTG-related protein 1). In addition, the subnuclear localization of the hSIN3B and the ETO homologues was also examined. Results: A ubiquitous expression of hSIN3B was observed in adult and fetal tissues. Results with both ectopically expressed proteins in COS-7 cells and endogeneous proteins in the K562 human erytholeukemia cell line demonstrated interactions between hSIN3B and ETO or MTG16 but not MTGR1. Furthermore, nuclear extract of primary placental cells showed complexes between hSIN3B and ETO. The interaction between hSIN3B and ETO required an intact amino-terminus of ETO and the NHR2 domain. A nucleolar localization of hSIN3B and all the ETO homologues was demonstrated upon overexpression in COS-7 cells, and confirmed for the endogeneously expressed proteins in K562 cells. However, hSIN3B did not colocalize or interact with the leukemia-associated AML1 -ETO. Conclusion: Our data from protein-protein interactions and immunolocalization experiments support that hSIN3B is a potential member of a corepressor complex involving selective ETO homologues.
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| 2. |
- Rondin Lindberg, Sofia
(author)
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Characterisation of the leukaemia-associated ETO homologues
- 2006
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Doctoral thesis (other academic/artistic)abstract
- Acute myeloid leukemia (AML) is commonly associated with balanced chromosomal translocations. Characteristically, these translocations lead to the fusion of two unrelated genes, resulting in the expression of an aberrant fusion protein. t(8;21) is one of the most common translocations found in patients with AML. It results in the expression of the chimeric protein AML1-ETO. AML1 is a transcription factor of crucial importance during hematopoiesis. The function of the fusion partner eight-twenty-one (ETO) is much less understood. The aim of this thesis was to characterise ETO and its two homologues, myeloid translocation gene 16 (MTG16) and myeloid translocation gene related protein 1 (MTGR1), to elucidate their role in normal and disregulated hematopoiesis. We studied the interaction patterns of the ETO homologues as well as their expression pattern in hematopoietic cells. We also examined the consequences of upregulation or downregulation of the proteins. We found that all the ETO homologues as well as AML1-ETO can interact with each other as determined by IP-Western experiments. We also found that the ETO homologues, but not AML1-ETO can bind to the corepressor SIN3B. The proposed interactions of the ETO homologues might have implications for the onset of leukaemia, since it opens up for an AML1-ETO mediated disturbance of ETO homologue function as well as a regulation of AML1-ETO function by the ETO homologues. Examination of the expression patterns of ETO homologues in hematopoetic cells show that the expression of ETO is restricted to erythroid cells, suggesting a role for ETO in erythropoiesis. MTG16 and MTGR1 are ubiquitously expressed in hematopoietic cells. However, the expression of MTG16 decresases during erythroid and granulocytic differentiation, suggesting a role for MTG16 in early hematopoiesis. Furthermore, the differential expression of the ETO homologues in hematopoetic cells implies a specific function for each protein in hematopoiesis. Attempts to knock-down MTG16 show a discrepancy between RNA levels and protein levels,which could propose a mechanism to keep the expression of MTG16 constant. Finally, overexpression experiments indicate a role for ETO in proliferation and apoptosis.
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| 3. |
- Rondin Lindberg, Sofia, et al.
(author)
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Interactions between the leukaemia-associated ETO homologues of nuclear repressor proteins.
- 2003
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In: European Journal of Haematology. - : Wiley. - 1600-0609 .- 0902-4441. ; 71:6, s. 439-447
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Journal article (peer-reviewed)abstract
- The eight-twenty-one (ETO) homologues, represented by ETO, myeloid transforming gene-related protein 1 (MTGR1) and myeloid transforming gene chromosome 16 (MTG16), are nuclear repressor proteins. ETO is part of the fusion protein acute myeloid leukaemia (AML)1-ETO, resulting from the translocation (8;21). Similarly, MTG16 is disrupted to become part of AML1/MTG16 in t(16;21). The aberrant expression of these chimeras could affect interplay between ETO homologues and contribute to the leukaemogenic process. We investigated possible interactions between the ETO homologues. Ectopic co-expression in COS-cells resulted in heterodimerisation of the various ETO homologues suggesting that they may co-operate. Similarly, the chimeric oncoprotein AML1-ETO interacted with both MTGR1 and MTG16. However, results from cell lines endogenously expressing more than one ETO homologue did not demonstrate co-precipitation. Results from IP-Western and size determination by gel filtration of deletion mutants expressed in COS-cells, indicated an important role of the HHR domain for oligomerisation. A role was also suggested for the Nervy domain in the homologue interactions. Our results suggest that ETO homologues can interact with each other as well as with AML1-ETO, although it is unclear as to what extent these interactions occur in vivo.
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