Alternative Super-Enhancer States Determine MYC Sensitivity to Notch and Brd4 Inhibitors in T Lymphoblastic Leukemia/Lymphoma

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 863-863
Author(s):  
Hongfang Wang ◽  
Yumi Yashiro-Ohtani ◽  
Chongzhi Zang ◽  
Yinling Joey Wong ◽  
Will Bailis ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Lines ◽  
Reporter Gene ◽  
Lymphoblastic Leukemia ◽  
Regulatory Elements ◽  
Proximal Promoter ◽  
Luciferase Reporter ◽  
Gene Promoters ◽  
Enhancer Element ◽  
Enhancer Region

Abstract Gain-of-function NOTCH1 mutations are oncogenic drivers in a high fraction of T-cell lymphoblastic leukemia/lymphoma (T-LL). These mutations variously cause increased production or stabilization of the free intracellular domain of NOTCH1, which regulates gene expression by forming a transcription complex with the DNA-binding factor RBPJ and coactivators of the MAML family. Using expression profiling and ChIP-seq, we have shown that NOTCH1/RBPJ complexes activate most target genes by binding to super-enhancers, large regulatory elements that switch on transcription through long-range interactions with gene promoters. MYC is a critical target of Notch in normal and malignant pre-T cells, but how Notch regulates MYC is unknown. To understand which regulatory element(s) regulate MYC expression, we used chromatin conformation capture (3C) assays to test the interaction between putative enhancer(s) and the MYC promoter in T-LL cell lines, and reporter gene assays to confirm enhancer function of candidate sites. We identified a distal site located >1 Mb 3’ of human and murine MYC termed the Notch-dependent MYC enhancer (NDME) that binds Notch transcription complexes and physically interacts with the MYC proximal promoter. An ~1 kb DNA fragment containing this site activates a luciferase reporter gene in a Notch-dependent fashion in T-LL cells but not in heterologous cell types. The Notch binding site lies within a large enhancer region (>600 kb in breadth) containing multiple discrete H3K27ac peaks. Remarkably, acute changes in Notch activation produce rapid changes in H3K27 acetylation across the entire enhancer region and the MYC promoter that correlate with NOTCH1/RBPJ complex binding and MYC expression. T-LL cells selected for resistance to gamma-secretase inhibitors (GSIs) exhibit epigenetic silencing of the NDME and loss of NDME looping interactions with the MYC promoter, yet maintain MYC expression. 3C analysis of GSI resistant cells shows preferential interaction between the MYC promoter and a more 3’ enhancer element recently described as a BRD4-dependent regulator of MYC expression in acute myeloid leukemia cells. In line with this observation, BRD4 antagonists are potent inhibitors of MYC expression in GSI resistant T-LL cells but not GSI-sensitive cells. We also studied a case of Notch-mutated early T-cell progenitor acute lymphoblastic leukemia (ETP-ALL). ChIP-Seq analysis of the leukemic blasts revealed an “AML-like” MYC enhancer chromatin state, and as predicted from our analysis of cell lines, the blasts rapidly down-regulated MYC in response to BRD4 inhibitor but not in response to GSI. These findings suggest that specific MYC chromatin states predict responsiveness to Notch and BRD4 inhibitors, and provide a rationale for use of Notch and BRD4 inhibitor combinations in Notch-mutated leukemias. Disclosures No relevant conflicts of interest to declare.

Transcriptional Regulation of the LMO2 T-Cell Leukaemia Oncogene.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2728-2728
Author(s):  
Josette-Renée Landry ◽  
Sarah Kinston ◽  
Kathy Knezevic ◽  
Anthony R. Green ◽  
Berthold Göttgens
Keyword(s):  
Stem Cells ◽  
T Cell ◽  
Cell Lines ◽  
Molecular Mechanisms ◽  
Regulatory Elements ◽  
Proximal Promoter ◽  
Cell Leukaemia ◽  
Haematopoietic Stem Cells ◽  
Haematopoietic Cells

Abstract Transcriptional control has long been identified as a key mechanism regulating the formation and subsequent behaviour of haematopoietic stem cells. We have used a comparative genomics approach to identify transcriptional regulatory elements of the LMO2 gene, a transcriptional cofactor originally identified through its involvement in T-cell leukaemia and subsequently shown to be critical for the formation of haematopoietic stem cells and endothelial development. An initial stringent search for homology between evolutionary distant species demonstrated that, apart from the coding exons, high level of identity between mammalian, amphibian and fish sequences was restricted to the proximal promoter region of LMO2. Real-time RT-PCR expression analysis identified this promoter as the predominant source of transcription in haematopoietic tissue. Transient and stable transfections indicated that the proximal promoter was active in haematopoietic progenitor and endothelial cell lines and this activity was shown to depend on three conserved Ets sites which were bound in vivo by Elf1, Fli1 and Ets1. Transgenic analysis demonstrated that the LMO2 proximal promoter was sufficient for expression in endothelial cells in vivo. However, no haematopoietic expression was observed indicating that additional enhancers are required to mediate transcription from the proximal promoter in haematopoietic cells. To identify additional elements involved in haematopoietic expression of LMO2, we have performed a less restrictive search for conserved sequences by comparing the human, dog, rat and mouse LMO2 loci to the marsupial opossum LMO2 locus. The addition of the opossum locus, and removal of the more distant fish and amphibian sequences from the alignment, resulted in the discovery of eleven conserved regions. These sequences represent candidate haematopoietic regulatory regions as they contain conserved transcription factor binding sites (E boxes, Ets and Gata sites) previously shown to regulate several other haematopoietic genes. We will present results from a systematic analysis of these regions for enhancer activity in both haematopoietic cell lines and transgenic mice, which suggest that several of these elements indeed act as enhancers. Taken together, our experiments will provide a framework for the transcriptional hierarchies within which LMO2 exerts its function in normal haematopoietic cells. Moreover, the current studies will serve as a platform to examine potential molecular mechanisms that can cause ectopic expression of LMO2 in T-cell progenitors with the ultimate consequence of developing T-ALL.

scholarly journals Type B Leukemogenic Virus Has a T-Cell-Specific Enhancer That Binds AML-1

2001 ◽  
Vol 75 (5) ◽  
pp. 2174-2184 ◽  
Author(s):  
Jennifer A. Mertz ◽  
Farah Mustafa ◽  
Shari Meyers ◽  
Jaquelin P. Dudley
Keyword(s):  
T Cell ◽  
Cell Lines ◽  
Protein Complexes ◽  
Regulatory Elements ◽  
Single Mutation ◽  
Type B ◽  
Enhancer Activity ◽  
Enhancer Element ◽  
Enhancer Function ◽  
T Cell Lines

ABSTRACT Type B leukemogenic virus (TBLV) induces rapidly appearing T-cell tumors in mice. TBLV is highly related to mouse mammary tumor virus (MMTV) except that TBLV long terminal repeats (LTRs) have a deletion of negative regulatory elements and a triplication of sequences flanking the deletion. To determine if the LTR triplication represents a viral enhancer element, we inserted the triplication upstream and downstream in either orientation relative to the thymidine kinase promoter linked to the luciferase gene. These experiments showed that upregulation of reporter gene activity by the TBLV triplication was relatively orientation independent, consistent with the activity of eukaryotic enhancer elements. TBLV enhancer activity was observed in T-cell lines but not in fibroblasts, B cells, or mammary cells, suggesting that enhancer function is cell type dependent. To analyze the transcription factor binding sites that are important for TBLV enhancer function, we prepared substitution mutations in a reconstituted C3H MMTV LTR that recapitulates the deletion observed in the TBLV LTR. Transient transfections showed that a single mutation (556M) decreased TBLV enhancer activity at least 20-fold in two different T-cell lines. This mutation greatly diminished AML-1 (recently renamed RUNX1) binding in gel shift assays with a mutant oligonucleotide, whereas AML-1 binding to a wild-type TBLV oligomer was specific, as judged by competition and supershift experiments. The 556 mutation also reduced TBLV enhancer binding of two other protein complexes, called NF-A and NF-B, that did not appear to be related to c-Myb or Ets. AML-1overexpression in a mammary cell line enhanced expression from the TBLV LTR approximately 30-fold. These data suggest that binding of AML-1 to the TBLV enhancer, likely in combination with other factors, is necessary for optimal enhancer function.

Gain-of-Function NOTCH1 Mutations Occur Frequently in Human T Cell Acute Lymphoblastic Leukemia.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4-4
Author(s):  
Andrew P. Weng ◽  
Adolfo A. Ferrando ◽  
Woojoong Lee ◽  
John P. Morris ◽  
Lewis B. Silverman ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Cell Lines ◽  
Reporter Gene ◽  
Lymphoblastic Leukemia ◽  
Reporter Gene Activity ◽  
Human T Cell ◽  
Cell Acute Lymphoblastic Leukemia ◽  
In Cis ◽  
Notch1 Mutations

Abstract NOTCH1 was discovered originally through its involvement in a rare (7;9) translocation found in human T cell acute lymphoblastic leukemia (T-ALL). Here, we report that >50% of human T-ALLs have activating NOTCH1 mutations, occurring as amino acid substitutions in an extracellular heterodimerization (HD) domain and/or as frameshift and stop codon mutations that result in the deletion of a C-terminal PEST destruction box. Normal pro-NOTCH1 is processed into a heterodimer consisting of an extracellular subunit and a transmembrane subunit, which associate non-covalently through the HD domain. NOTCH1 activation is triggered by binding of Serrate or Delta-like ligands to the extracellular subunit, which induces successive proteolytic cleavages in the transmembrane subunit that are dependent on i) metalloproteases and ii) gamma-secretase. The γ-secretase cleavage releases intracellular NOTCH1 (ICN1), which translocates to the nucleus and forms a transcriptional activation complex with the transcription factor CSL and co-activators of the Mastermind family. Normal turnover of ICN1 is regulated by the C-terminal PEST sequence. Data pointing to the existence of frequent abnormalities of NOTCH1 in T-ALL stemmed from a functional screen of 30 T-ALL cell lines. This identified five T-ALL cell lines that underwent growth arrest in response to i) treatment with an inhibitor γ-secretase, and ii) retroviral transduction of dominant negative Mastermind-like-1. Sequencing of of cDNAs from 4 of these 5 cell lines demonstrated both a missense mutation in the HD domain and a frameshift mutation in the PEST domain lying in cis in the same NOTCH1 allele. Subsequent sequencing of genomic DNA obtained from bone marrow lymphoblasts of 96 children and adolescents with T-ALL demonstrated identical or similar mutations in NOTCH1 in 53 samples (55.2%). Mutations in the HD domain alone were observed in 26 cases (27.1%), in the PEST domain alone in 11 cases (11.4%), and in both the HD and PEST domains in 16 cases (16.7%). Mutations were observed in tumors associated with expression of HOX11 (2/3), HOX11L2 (10/13; 77%), TAL1 (12/31; 39%), LYL1 (9/14; 64%), MLL-ENL (1/3) or CALM-AF10 (1/2), which span the major molecular T-ALL subtypes. In contrast, NOTCH1 mutations were not observed in genomic DNAs samples obtained from B-ALL lymphoblasts (N=89), or from T-ALL patients with NOTCH1-associated disease at the time of clinical remission (N=4). Reporter gene assays conducted with plasmids expressing normal and mutated forms of NOTCH1 showed that a PEST deletion or various HD mutations alone caused ~1.5-fold and 3–9-fold stimulations of reporter gene activity, respectively, whereas normal NOTCH1 lacked intrinsic signaling activity. More strikingly, the combination of various HD mutations and a PEST deletion in cis caused synergistic 20–40-fold stimulations of reporter gene activity that were completely abrogated by a γ-secretase inhibitor, indicating that signaling depends on proteolysis. These results suggest a model in which HD domain mutations promote ICN1 production, and PEST domain mutations enhance ICN1 stability. Our findings greatly expand the role of NOTCH1 in the pathogenesis of human T-ALL, and provide a rationale for targeted therapies that interfere with NOTCH signaling.

Transcriptional Regulation of Oncogenic MEF2C In T-Cell Acute Lymphoblastic Leukemia (T-ALL).

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3636-3636
Author(s):  
Stefan Nagel ◽  
Letizia Venturini ◽  
Corinna Meyer ◽  
Maren Kaufmann ◽  
Michaela Scherr ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Ectopic Expression ◽  
Regulatory Elements ◽  
Hematopoietic Stem ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Bhlh Proteins

Abstract Abstract 3636 Myocyte enhancer factor 2C (MEF2C) is a transcription factor of the MADS-box family which is physiologically expressed in hematopoietic stem cells and during development of B-cells. Recently, we identified ectopic expression of MEF2C in T-cell acute lymphoblastic leukemia (T-ALL) cell lines activated either via chromosomally mediated ectopic expression of homeodomain protein NKX2-5 or via deletion of non-coding exon and promoter regions at 5q14, suggesting loss of negative regulatory elements. Our aim was to identify additional transcriptional regulators of MEF2C in T-ALL. Therefore, we analyzed the sequence of the MEF2C 5′-region, thus identifying potential regulatory binding sites for GFI1B, basic helix-loop-helix (bHLH) proteins, STAT5 and HOXA9/HOXA10. Overexpression studies demonstrated MEF2C activation by GFI1B (strong), LYL1 and TAL1 leukemic bHLH proteins (weak), and inhibition by STAT5 (strong) and HOXA9/HOXA10 (weak). Chromatin-Immuno-Precipitation analysis demonstrated direct binding of GFI1B, LYL1 and STAT5 but not of HOXA10 to the MEF2C 5′-region in T-ALL cells. However, HOXA9/HOXA10 activated expression of NMYC which in turn mediated MEF2C repression, indicating an indirect mode of MEF2C regulation. Chromosomal deletion of the 5′-MEF2C STAT5 binding site in LOUCY cells by del(5)(q14), reduced expression levels of STAT5 protein in some MEF2C-positve T-ALL cell lines, and the presence of inhibitory IL7-JAK-STAT5-signaling highlighted the repressive impact of this factor in MEF2C regulation. Taken together, our results indicate that ectopic expression of MEF2C in T-ALL cells is mainly regulated via activating leukemic transcription factors GFI1B or NKX2-5 and by escaping inhibitory STAT5-signaling. Disclosures: No relevant conflicts of interest to declare.

scholarly journals miR106a-363 Cluster Has Oncogenic Potential in Childhood T-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 5142-5142
Author(s):  
Monika Drobna ◽  
Bronislawa Szarzynska-Zawadzka ◽  
Maria Kosmalska ◽  
Roman Jaksik ◽  
Tomasz Szczepanski ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Cell Lines ◽  
Target Genes ◽  
Lymphoblastic Leukemia ◽  
Luciferase Reporter ◽  
Pathway Enrichment Analysis ◽  
Thermo Fisher Scientific ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Fisher Scientific

Abstract T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy originating from T-cell precursors and is characterized by high genetic, immunophenotypic, and clinical heterogeneity. MicroRNAs (miRNAs) belong to the class of small noncoding RNAs and are implicated in the regulation of hematopoiesis and in the development of leukemia. miRNAs control expression of their target genes at the post-transcriptional level by blocking translation of messenger RNAs (mRNAs) or promoting their degradation. Some miRNAs are encoded within clusters, giving rise to policistronic transcripts. Such miRNAs are co-expressed and may co-regulate the expression of genes involved in certain biological processes and pathways. In our recent study we performed miRNA profiling in pediatric T-ALL using Next-Generation Sequencing (Dawidowska M et al. Blood 2017; 130:1443) and identified miRNAs differentially expressed in T-ALL. The set of overexpressed miRNAs included, among others, miR-20b-5p, miR-363-3p and miR-92a-2-5p, belonging to a cluster of six miRNAs: miR-106a-363 (ChrXq26.2). miR-106a-363 cluster is a paralog of miR-17-92 cluster (Chr13q31.3), a prototypic oncogenic cluster of eminent importance in human hematopoietic cancers, with reported role in T-ALL pathogenesis (Mavrakis KJ et al., Nature Cell Biology 2010, 12:4). Despite the similarity of seed sequences between miRNAs from miR-17-92 and miR-106a-363 clusters, the significance of miR-106a-363 cluster in T-ALL remains to be elucidated. In this study we investigated the expression of the miR-20b-5p, miR-363-3p and miR-92a-2-5p in children with T-ALL, healthy donor thymocytes, normal bone marrow samples and 6 T-ALL cell lines. RT-qPCR analysis (TaqMan Advanced miRNA Assays; Thermo Fisher Scientific) confirmed overexpression of 2 miRNAs from cluster miR-106a-363 (miR-20b-5p and miR-363-3p) in children with T-ALL and in T-ALL cell lines, suggesting their oncogenic function. To predict potential target genes of overexpressed miRNAs belonging to miR106a-363 cluster, we applied 8 target prediction algorithms and pathway enrichment analysis. This revealed the enrichment of miR-20b-5p and miR-363-3p target genes in GO term: positive regulation of apoptosis. We further validated predicted miRNA-mRNA interactions (Dual Luciferase Reporter Assays; Promega) confirming the majority of them (e.g. PTEN, FBXW7, BCL2L11). Finally, we assessed the effect of mimicry/inhibition (miRVana, Thermo Fisher Scientific) of overexpressed miRNAs from miR-106a-363 cluster on proliferation, cell cycle distribution and apoptosis in 3 T-ALL cell lines. Overexpression of miR-20b-5p and miR-363-3p in CCRF-CEM, DND-41 and P12-Ichikawa cells resulted in increased proliferation and inhibited apoptosis. To summarize, in this study we showed that miRNAs belonging to miR-106a-363 cluster directly interact with mRNAs implicated in the regulation of apoptosis and that miR-20b-5p and miR-363-3p have pro-proliferative and anti-apoptotic effects in T-ALL cells in vitro. These results indicate that miR-106a-363 cluster may have an oncogenic role in the pathogenesis of T-ALL via suppression of pro-apoptotic genes. Research funded by National Science Centre, Poland grants: 2014/15/B/NZ2/03394, 2017/25/N/NZ2/01132 and National Centre of Research and Development (NCRD) grant STARTEGMED3/304586/5/NCBR/2017. Disclosures No relevant conflicts of interest to declare.

scholarly journals T cell receptor beta gene has two downstream DNase I hypersensitive regions. Possible mechanisms of tissue- and stage-specific gene regulation.

1989 ◽  
Vol 169 (6) ◽  
pp. 2097-2107 ◽  
Author(s):  
Y Hashimoto
Keyword(s):  
Gene Expression ◽  
T Cell ◽  
Cell Lines ◽  
Regulatory Elements ◽  
Dnase I ◽  
The Other ◽  
Specific Gene ◽  
Enhancer Element ◽  
Tissue Specific ◽  
T Cell Lines

Two DNase I-hypersensitive regions were identified downstream of the TCR gene constant region. One of these regions is located at the site of a putative enhancer element and was observed only in T cell lines and not in cell lines derived from other tissues. The other DNase-hypersensitive region was also detected only in T cell lines but only in those expressing TCR-beta RNA. Thus, the first region is probably tissue specific, while the second region is probably tissue and stage specific. The DNA sequence of the second DNase I-hypersensitive region revealed several stretches of nucleotides that are characteristic of consensus sequences for regulatory elements. These results, together with the observations in transgenic mice that indicate a requirement for two distinct regions for optimal TCR gene expression, suggest the presence of at least two regulatory regions downstream of the C-beta-2 region; one is an enhancer region and the other is a transcriptionally related regulatory region. The tissue/stage specificity of these DNase I-hypersensitive regions supports the notion that changes in chromatin structure control tissue-specific gene expression.

scholarly journals Multi-omic profiling of pituitary thyrotropic cells and progenitors

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Alexandre Z. Daly ◽  
Lindsey A. Dudley ◽  
Michael T. Peel ◽  
Stephen A. Liebhaber ◽  
Stephen C. J. Parker ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Pituitary Gland ◽  
Cell Lines ◽  
Binding Sites ◽  
Critical Factor ◽  
Regulatory Elements ◽  
Thyroid Stimulating Hormone ◽  
Neuroendocrine Cells ◽  
Bzip Transcription Factor ◽  
Enhancer Element

Abstract Background The pituitary gland is a neuroendocrine organ containing diverse cell types specialized in secreting hormones that regulate physiology. Pituitary thyrotropes produce thyroid-stimulating hormone (TSH), a critical factor for growth and maintenance of metabolism. The transcription factors POU1F1 and GATA2 have been implicated in thyrotrope fate, but the transcriptomic and epigenomic landscapes of these neuroendocrine cells have not been characterized. The goal of this work was to discover transcriptional regulatory elements that drive thyrotrope fate. Results We identified the transcription factors and epigenomic changes in chromatin that are associated with differentiation of POU1F1-expressing progenitors into thyrotropes using cell lines that represent an undifferentiated Pou1f1 lineage progenitor (GHF-T1) and a committed thyrotrope line that produces TSH (TαT1). We compared RNA-seq, ATAC-seq, histone modification (H3K27Ac, H3K4Me1, and H3K27Me3), and POU1F1 binding in these cell lines. POU1F1 binding sites are commonly associated with bZIP transcription factor consensus binding sites in GHF-T1 cells and Helix-Turn-Helix (HTH) or basic Helix-Loop-Helix (bHLH) factors in TαT1 cells, suggesting that these classes of transcription factors may recruit or cooperate with POU1F1 binding at unique sites. We validated enhancer function of novel elements we mapped near Cga, Pitx1, Gata2, and Tshb by transfection in TαT1 cells. Finally, we confirmed that an enhancer element near Tshb can drive expression in thyrotropes of transgenic mice, and we demonstrate that GATA2 enhances Tshb expression through this element. Conclusion These results extend the ENCODE multi-omic profiling approach to the pituitary gland, which should be valuable for understanding pituitary development and disease pathogenesis. Graphical abstract

scholarly journals Human common acute lymphoblastic leukemia-derived cell lines are competent to recombine their T-cell receptor delta/alpha regions along a hierarchically ordered pathway

Blood ◽  
1992 ◽  
Vol 80 (9) ◽  
pp. 2353-2362
Author(s):  
TE Hansen-Hagge ◽  
S Yokota ◽  
HJ Reuter ◽  
K Schwarz ◽  
CR Bartram
Keyword(s):  
Tissue Culture ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Lines ◽  
Signal Sequence ◽  
Lymphoblastic Leukemia ◽  
Cell Receptor ◽  
Culture Conditions ◽  
Initial Culture ◽  
Human B Cell

Rearrangements of the T-cell receptor (TCR) delta locus are observed in the majority of human B-cell precursor acute lymphoblastic leukemias (ALL) with a striking predominance of V delta 2(D)D delta 3 recombinations in common ALL (cALL) patients. Recently, we and others showed that almost 20% of cALL cases are characterized by further recombination of V delta 2(D)D delta 3 segments to J alpha elements, thereby deleting the TCR delta locus in analogy to the delta Rec/psi J alpha pathway in differentiating alpha/beta-positive T cells. We report here that two human cALL-derived cell lines, REH and Nalm-6, are competent to recombine the TCR delta/alpha locus under standard tissue culture conditions. Analysis of different REH subclones obtained by limiting dilution of the initial culture showed a biased recombination of V delta 2D delta 3 to distinct J alpha elements. During prolonged tissue culture, a subclone acquired growth advantage and displaced parental cells as well as other subclones. Frequently, the DJ junctions of REH subclones contained extended stretches of palindromic sequences derived from modified D delta 3 coding elements. The other cell line, Nalm-6, started the TCR delta/alpha recombination with an unusual signal joint of a cryptic recombinase signal sequence (RSS) upstream of D delta 3 to the 3′ RSS of D delta 3. The RSS dimer was subsequently rearranged in all investigated subclones to an identical J alpha element. Both cell lines might become valuable tools to unravel the complex regulation of TCR delta/alpha recombination pathways in malignant and normal lymphopoiesis.

scholarly journals Non-invasive somatotransgenic bioimaging in living animals

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 1216 ◽  
Author(s):  
Juliette M. Delhove ◽  
Rajvinder Karda ◽  
Lorna M. FitzPatrick ◽  
Suzanne M.K. Buckley ◽  
Simon N. Waddington ◽  
...  
Keyword(s):  
Gene Expression ◽  
Reporter Gene ◽  
Viral Vectors ◽  
Es Cells ◽  
Embryonic Stem ◽  
Whole Body ◽  
Luciferase Reporter ◽  
Gene Promoters ◽  
Luciferase Reporter Gene ◽  
Endogenous Gene

Bioluminescence imaging enables noninvasive quantification of luciferase reporter gene expression in transgenic tissues of living rodents. Luciferase transgene expression can be regulated by endogenous gene promoters after targeted knock-in of the reporter gene, usually within the first intron of the gene. Even using CRISPR/Cas9 mediated genome editing this can be a time consuming and costly process. The generation of germline transgenic (GLT) rodents by targeted genomic integration of a gene expression cassette in embryonic stem (ES) cells is commonplace but results in the wastage of large numbers of animals during colony generation, back-crossing and maintenance. Using a synthetic/truncated promoter-driven luciferase gene to study promoter activity in a given tissue or organ of a GLT also often results in unwanted background luciferase activity during whole-body bioluminescent imaging as every cell contains the reporter. We have developed somatotransgenic bioimaging; a method to generate tissue-restricted transcription factor activated luciferase reporter (TFAR) cassettes in rodents that substantially reduces the number of animals required for experimentation. Bespoke designed TFARs are delivered to newborn pups using viral vectors targeted to specific organs by tissue-tropic pseudotypes. Retention and proliferation of TFARs is facilitated by stem/progenitor cell transduction and immune tolerance to luciferase due to the naïve neonatal immune system. We have successfully applied both lentiviral and adeno-associated virus (AAV) vectors in longitudinal rodent studies, targeting TFARs to the liver and brain during normal development and in well-established disease models. Development of somatotransgenic animals has broad applicability to non-invasively determine mechanistic insights into homeostatic and disease states and assess toxicology and efficacy testing. Somatotransgenic bioimaging technology is superior to current whole-body, light-emitting transgenic models as it reduces the numbers of animals used by generating only the required number of animals. It is also a refinement over current technologies given the ability to use conscious, unrestrained animals.

scholarly journals Promoter analysis of the DHCR24 (3β-hydroxysterol Δ24-reductase) gene: characterization of SREBP (sterol-regulatoryelement-binding protein)-mediated activation

2012 ◽  
Vol 33 (1) ◽  
Author(s):  
Lidia A. Daimiel ◽  
María E. Fernández-Suárez ◽  
Sara Rodríguez-Acebes ◽  
Lorena Crespo ◽  
Miguel A. Lasunción ◽  
...  
Keyword(s):  
Cellular Response ◽  
Binding Protein ◽  
Regulatory Element ◽  
Cholesterol Biosynthesis ◽  
Regulatory Elements ◽  
Proximal Promoter ◽  
Luciferase Reporter ◽  
Mobility Shift ◽  
Gene Characterization ◽  
Cis Acting

DHCR24 (3β-hydroxysterol Δ24-reductase) catalyses the reduction of the C-24 double bond of sterol intermediates during cholesterol biosynthesis. DHCR24 has also been involved in cell growth, senescence and cellular response to oncogenic and oxidative stress. Despite its important roles, little is known about the transcriptional mechanisms controlling DHCR24 gene expression. We analysed the proximal promoter region and the cholesterol-mediated regulation of DHCR24. A putative SRE (sterol-regulatory element) at −98/−90 bp of the transcription start site was identified. Other putative regulatory elements commonly found in SREBP (SRE-binding protein)-targeted genes were also identified. Sterol responsiveness was analysed by luciferase reporter assays of approximately 1 kb 5′-flanking region of the human DHCR24 gene in HepG2 and SK-N-MC cells. EMSAs (electrophoretic mobility-shift assays) and ChIP (chromatin immunoprecipitation) assays demonstrated cholesterol-dependent recruitment and binding of SREBPs to the putative SRE. Given the presence of several CACCC-boxes in the DHCR24 proximal promoter, we assessed the role of KLF5 (Krüppel-like factor 5) in androgen-regulated DHCR24 expression. DHT (dihydrotestosterone) increased DHCR24 expression synergistically with lovastatin. However, DHT was unable to activate the DHCR24 proximal promoter, whereas KLF5 did, indicating that this mechanism is not involved in the androgen-induced stimulation of DHCR24 expression. The results of the present study allow the elucidation of the mechanism of regulation of the DHCR24 gene by cholesterol availability and identification of other putative cis-acting elements which may be relevant for the regulation of DHCR24 expression.

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