| 71. |
- Thorpe, Michael
(författare)
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Haematopoietic Serine Proteases : A Cleavage Specificity Analysis
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mast cells are innate immune cells, historically involved in allergy responses involving IgE. Through this, they have earned a reputation as a fairly detrimental cell type. Their beneficial roles remain somewhat enigmatic although they clearly have the ability to modulate the immune system. This is due to their ability to synthesise many cytokines and chemokines as well as immediately release potent granule-stored mediators. One such mediator is a serine protease, chymase, which has been targeted by pharmaceutical companies developing inhibitors for use in inflammatory conditions.In order to address roles of the proteases, information regarding their cleavage specificity using substrate phage display can help find potential in vivo substrates. The human chymase cleaves substrates with aromatic amino acids in the P1 position and has a preference for negatively charged amino acids in the P2’ position. The molecular interactions mediating this P2’ preference was investigated by site-directed mutagenesis, where Arg143 and Lys192 had a clear effect in this selectivity.As humans express one chymase and rodents express multiple chymases, extrapolating data between species is difficult. Here, the crab-eating macaque was characterised, which showed many similarities to the human chymase including a near identical extended cleavage specificity and effects of human chymase inhibitors. Appropriate models are needed when developing human inhibitors for therapeutic use in inflammatory conditions.The effects of five specific chymase inhibitors in development were also tested. The selectivity of inhibitors was dependent on both Arg143 and Lys192, with a greater effect of Lys192. Identification of residues involved in specific inhibitor interactions is important for selective inhibitor development.Another innate cell type, the NK cell, is important in virus and tumour defence. In the channel catfish, a serine protease from an NK-like cell, granzyme-like I, was characterised. A strict preference for Met in the P1 position was seen, and caspase 6 was identified as a potential in vivo target. This may highlight a novel apoptosis-inducing mechanism from a similar cell type has been conserved for approximately 400 myr.Here, important residues mediating chymases’ specificity and interactions with inhibitors has been addressed, as well as finding a new animal model for providing ways to combat their roles in pathological settings.
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| 72. |
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| 73. |
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| 74. |
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| 75. |
- Ullmark, Tove, et al.
(författare)
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Anti-apoptotic quinolinate phosphoribosyltransferase (QPRT) is a target gene of Wilms' tumor gene 1 (WT1) protein in leukemic cells
- 2017
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Ingår i: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 0006-291X. ; 482:4, s. 802-807
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Tidskriftsartikel (refereegranskat)abstract
- Wilms' tumor gene 1 (WT1) is a zinc finger transcription factor that has been implicated as an oncogene in leukemia and several other malignancies. When investigating possible gene expression network partners of . WT1 in a large acute myeloid leukemia (AML) patient cohort, one of the genes with the highest correlation to . WT1 was quinolinate phosphoribosyltransferase (QPRT), a key enzyme in the . de novo nicotinamide adenine dinucleotide (NAD+) synthesis pathway. To investigate the possible relationship between . WT1 and . QPRT, we overexpressed . WT1 in hematopoietic progenitor cells and cell lines, resulting in an increase of . QPRT expression. WT1 knock-down gave a corresponding decrease in . QPRT gene and protein expression. Chromatin-immunoprecipitation revealed WT1 binding to a conserved site in the first intron of the . QPRT gene. Upon overexpression in leukemic K562 cells, QPRT conferred partial resistance to the anti-leukemic drug imatinib, indicating possible anti-apoptotic functions, consistent with previous reports on glioma cells. Interestingly, the rescue effect of QPRT overexpression was not correlated to increased NAD + levels, suggesting NAD + independent mechanisms. We conclude that . QPRT, encoding a protein with anti-apoptotic properties, is a novel and direct target gene of WT1 in leukemic cells.
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| 76. |
- Ullmark, Tove, et al.
(författare)
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Distinct global binding patterns of the Wilms' tumor gene 1 (WT1) -KTS and +KTS isoforms in leukemic cells
- 2017
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 1592-8721 .- 0390-6078. ; 102:2, s. 336-345
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Tidskriftsartikel (refereegranskat)abstract
- The zinc finger transcription factor Wilms' tumor gene 1 (WT1) acts as an oncogene in acute myeloid leukemia. A naturally occurring alternative splice event between zinc fingers three and four, removing or retaining three amino acids (+/-KTS), is believed to change the DNA binding affinity of WT1, although there are conflicting data regarding the binding affinity and motifs of the different isoforms. Increased expression of WT1 -KTS at the expense of WT1 +KTS isoform associates with poor prognosis in acute myeloid leukemia. We determined the genome-wide binding pattern of WT1 -KTS and WT1 +KTS in leukemic K562 cells by chromatin immunoprecipitation and deep sequencing (ChIP-seq). Motif discovery revealed distinct binding motifs for the isoforms, some of which have been previously reported as WT1 binding sites. We discovered that the WT1 -KTS isoform predominantly binds close to transcription start sites and to enhancers, in a similar fashion to other transcription factors, whereas WT1 +KTS binding is rather enriched within gene bodies. We observed a significant overlap between WT1 -KTS and WT1 +KTS target genes, despite the binding sites being distinct. Motif discovery revealed distinct binding motifs for the isoforms, some of which have been previously reported as WT1 binding sites. Additional analyses showed that both WT1 -KTS and WT1 +KTS target genes are more likely to be transcribed than non-targets, and are involved in cell proliferation, cell death, and development. Our study provides evidence that WT1 -KTS and WT1 +KTS share target genes yet still bind distinct locations, indicating isoform-specific regulation in transcription of genes related to cell proliferation and differentiation, consistent with involvement of WT1 in acute myeloid leukemia.
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| 77. |
- Ullmark, Tove, et al.
(författare)
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DNA and RNA binding by the Wilms' tumour gene 1 (WT1) protein +KTS and −KTS isoforms—From initial observations to recent global genomic analyses
- 2018
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Ingår i: European Journal of Haematology. - : Wiley. - 0902-4441. ; 100:3, s. 229-240
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Forskningsöversikt (refereegranskat)abstract
- The Wilms' tumour gene 1 protein (WT1) is a zinc finger transcription factor found indispensable for foetal development. WT1 has also been implicated in the development of tumours in several organ systems, including acute myeloid leukaemia (AML). Four main WT1 isoforms come from 2 alternative splice events. One alternative splice results in the inclusion or exclusion of 3 amino acids, KTS, between zinc fingers 3 and 4 in the WT1 protein. The KTS insert has been extensively investigated due to the functional implications for DNA and RNA binding. In this review, we provide an overview of the research into the isoforms containing or lacking the KTS insert in leukaemic cells, as well as the research into the binding patterns of the WT1 −KTS and +KTS isoforms to DNA and RNA. Finally, we connect the results of the DNA binding research to the ChIP-CHIP and ChIP-Seq investigations into the global genomic binding of the WT1 protein that have recently been performed.
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| 78. |
- Ullmark, Tove, et al.
(författare)
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Global binding pattern of the Wilms' tumor gene 1 (WT1) +17AA -KTS isoform in leukemic cells
- 2016
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Ingår i: Cancer Research. - 1538-7445. ; 76:14 Suppl.
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Konferensbidrag (refereegranskat)abstract
- The aim of this study was to investigate the global DNA-binding pattern of Wilms' tumor gene 1 (WT1) in leukemic cells. Clinical and preclinical data indicate the zinc finger transcription factor WT1 as an oncogene, but the full target gene repertoire of WT1 in leukemic cells has not been previously characterized. The -KTS isoforms (excluding the three amino acid (KTS) insert between zinc finger three and four) are considered as the most efficient DNA-binders. Among these, the 17AA isoform (including 17 amino acids encoded by exon 5) is the most abundant one. To specifically analyze the DNA-binding of WT1(+17AA/-KTS) in leukemic cells, we generated a K562 clone that stably expressed BIO-tagged WT1(+17AA/-KTS), as well as the biotinylating enzyme Bir A. From the cells chromatin immunoprecipitation (ChIP) by streptavidin capture was performed followed by sequencing with a minimum of 50 million reads per sample. After alignment to the genome and peak calling, peaks were characterized and compared to available K562 tracks in the ENCODE database. We found that 45% of identified WT1(+17AA/-KTS) peaks are in the proximity of transcription start sites (promoter area, first exon or first intron) of target genes, whereas only 11% of randomized peaks were found here. Within the peaks we show strong enrichment for three different previously published WT1-binding motifs. Comparison to ENCODE tracks showed that WT1(+17AA/-KTS) peaks are in close proximity to binding sites of other transcription factors, to histone marks for actively transcribed genes, and to binding sites of chromatin modifiers. Considering peaks within promoters and gene bodies only (for safe assignment to a target gene), Gene Ontology (GO) analysis revealed enrichment of GO groups important for proliferation, cell death, embryonic development, and cell motility. In conclusion, WT1(+17AA/-KTS) binds close to transcription start sites in areas of active transcription. The target genes implicated in proliferation, cell death, cell signaling and motility adds to the growing evidence of WT1 as an effector gene in leukemia.
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| 79. |
- Vidovic, Karina, et al.
(författare)
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Leukemia associated mutant Wilms' tumor gene 1 protein promotes expansion of human hematopoietic progenitor cells.
- 2013
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Ingår i: Leukemia Research: A Forum for Studies on Leukemia and Normal Hemopoiesis. - : Elsevier BV. - 1873-5835 .- 0145-2126. ; 37:10, s. 1341-1349
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Tidskriftsartikel (refereegranskat)abstract
- The transcription factor Wilms' tumor gene 1 (WT1) is highly expressed in the majority of leukemias, suggesting a role in leukemogenesis. Acquired WT1 mutations are reported as an independent predictor of poor clinical outcome, and mutations resulting in deletion of the entire DNA-binding zinc-finger domain (WT1delZ), is the most common type. The aim of this study was to study cellular effects of WT1(delZ) that may contribute to an oncogenic phenotype. We found that expression of WT1(delZ) supported proliferation of human hematopoietic CD34(+) progenitor cells. Moreover, WT1(delZ) transduced cells expressed erythroid markers, including raised levels of STAT5, independently of addition of erythropoietin. At the global gene expression level, WT1(delZ) caused upregulation of genes related to cell division and genes associated with erythroid maturation, in the absence of added erythropoietin. Our results indicate that WT1(delZ) promotes cell proliferation and expansion of progenitor cells, consistent with a possible role in leukemogenesis.
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| 80. |
- Vidovic, Karina, et al.
(författare)
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Wilms' tumor gene 1 protein represses the expression of the tumor suppressor interferon regulatory factor 8 in human hematopoietic progenitors and in leukemic cells.
- 2010
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Ingår i: Leukemia. - : Springer Science and Business Media LLC. - 1476-5551 .- 0887-6924. ; 24:5, s. 992-1000
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Tidskriftsartikel (refereegranskat)abstract
- Wilms' tumor gene 1 (WT1) is a transcription factor involved in developmental processes. In adult hematopoiesis, only a small portion of early progenitor cells express WT1, whereas most leukemias show persistently high levels, suggesting an oncogenic role. We have previously characterized oncogenic BCR/ABL1 tyrosine kinase signaling pathways for increased WT1 expression. In this study, we show that overexpression of BCR/ABL1 in CD34+ progenitor cells leads to reduced expression of interferon regulatory factor 8 (IRF8), in addition to increased WT1 expression. Interestingly, IRF8 is known as a tumor suppressor in some leukemias and we investigated whether WT1 might repress IRF8 expression. When analyzed in four leukemia mRNA expression data sets, WT1 and IRF8 were anticorrelated. Upon overexpression in CD34+ progenitors, as well as in U937 cells, WT1 strongly downregulated IRF8 expression. All four major WT1 splice variants induced repression, but not the zinc-finger-deleted WT1 mutant, indicating dependence on DNA binding. A reporter construct with the IRF8 promoter was repressed by WT1, dependent on a putative WT1-response element. Binding of WT1 to the IRF8 promoter was demonstrated by chromatin immunoprecipitation. Our results identify IRF8 as a direct target gene for WT1 and provide a possible mechanism for oncogenic effects of WT1 in leukemia.Leukemia advance online publication, 18 March 2010; doi:10.1038/leu.2010.33.
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