963 research outputs found
FOG-1, a transcriptional regulator within the haematopoietic system
No full textFriend of GATA-1 (FOG-1) is a member of the friend of GATA (FOG)
family of proteins, which consists of large multitype zinc finger cofactors that
bind to the amino zinc finger of GATA transcription factors and modulate their
activity. FOG-1 also interacts with the C-terminal binding protein (CtBP),
mainly known as a corepressor and the nucleosome remodelling and histone
deacetylase repressive (NuRD) complex ; thus, integrating FOG-1 into the
transcription factor and chromatin modifier networks. Remarkably, the protein
activates or represses gene transcription by facilitating binding of GATA
factors to DNA, recruiting chromatin remodelling complexes, or by stabilizing
tissue-specific chromatin loops. Physical interaction between FOG and GATA
proteins in vivo is essential for the development of a broad array of tissues,
reflecting the overlapping expression patterns of these factors. Notably, within
the haematopoietic system, FOG-1 is absent in most of the myeloid lineages ;
it is expressed at high level in multipotent progenitors, erythroid and
megakaryocytic cells, low level in lymphoid and haematopoietic stem cells.
The cofactor is essential for differentiation of the erythroid and
megakaryocytic lineages, notably by interacting with GATA-1. FOG-1 also
plays a role in the T-lineage by repressing GATA-3 dependent induction of
Th2 development. Interestingly, overexpression of FOG-1 in avian
eosinophils, which do not normally express FOG-1, reprograms these
differentiated cells into multipotent cells. To study FOG-1 in mammals, we
used a novel transgenic mouse model strategy which we had designed to
generate mice with conditional overexpression of FOG-1. Our work with
enforced expression of FOG-1 in the whole murine haematopoietic system led
to a reduction in the number of circulating eosinophils, confirming and
extending to mammals the previously reported role of FOG-1 in repressing
this lineage development. Strikingly, we have identified the expression of
FOG-1 in early B lymphocytes, but not in late developmental stages such as
mature B cells and plasma cells. Moreover, FOG-1 function had never been
described in the B-lineage, where GATA factors are not expressed. Therefore,
we were intrigued by both the regulated expression of FOG-1 during B cell
development and its molecular mechanism of action in the absence of GATA
factors. Thus, we generated transgenic mice in which FOG-1 expression was
enforced at a physiologically relevant level in the B lymphoid system : in
mature B cells and from early B cell stages. We found that sustained FOG-1
expression in mature and late B cells did not affect their development or
function, contrary to our expected hypothesis. Although the mice
overexpressing FOG-1 from early B cell lineages showed only a weak
phenotype, we extensively studied FOG-1 partners in early B cell stages.
Indeed, describing FOG-1 molecular mechanism of action in the absence of
GATA factors is a question that warrant further investigation. We notably
found FOG-1 in complex with Ikaros, a transcription factor well described as
crucial for B cell development. The cofactor was also found associated to the
CtBP and NuRD epigenetic complexes in B cell lines
GATA repeats in the genome of Asellus aquaticus (Crustacea, Isopoda).
No full textA 500 bp fragment of Drosophila genomic DNA containing 37 copies of the tetranucleotide GATA was used to probe, by Southern DNA blotting and in situ hybridization, two natural populations of the isopod crustacean Asellus aquaticus collected from the Sarno and Tiber rivers. This species does not have a recognizable sex chromosome pair. In a number of males from the Sarno population chromomycin A3 staining reveals a heteromorphic chromosome pair. The heterochromosome has two blocks of heterochromatin. After digestion of genomic DNA with six restriction endonucleases and hybridization with the GATA probe, the two populations exhibit different fragment length patterns. No sex-linked pattern was observed in either population. In situ hybridization to chromosomes of males and females from the Sarno population does not reveal any sex-specific pattern of labelling and indicates a scattered distribution of GATA sequences on most chromosomes with some areas of preferential concentration. The heterochromatic areas of the male heterochromosome are not labelled
CLDF dataset for the GATA (Grammars Across Time Analyzed) dataset
No full text<p>Cite the dataset as:</p>
<blockquote>
<p>Frederic Blum, Carlos Barrientos, Adriano Ingunza, Damian E. Blasi & Roberto Zariquiey. (2023). CLDF dataset for `Grammars Analyzed Across Time` (GATA).</p>
</blockquote>
Arronzar remisión de V. gata de arronzar.
No full text[ES] Definición del término Arronzar remisión de V. gata de arronzar. en el diccionario Dicter.[EN] Definition of the word Arronzar remisión de V. gata de arronzar. in the dictionary Dicter
Distinct gene expression patterns in skeletal and cardiac muscle are dependent on common regulatory sequences in the MLC1/3 locus
No full textThe myosin light-chain 1/3 locus (MLC1/3) is regulated by two promoters and a downstream enhancer element which produce two protein isoforms in fast skeletal muscle at distinct stages of mouse embryogenesis. We have analyzed the expression of transcripts from the internal MLC3 promoter and determined that it is also expressed in the atria of the heart. Expression from the MLC3 promoter in these striated muscle lineages is differentially regulated during development. In transgenic mice, the MLC3 promoter is responsible for cardiac-specific reporter gene expression while the downstream enhancer augments expression in skeletal muscle. Examination of the methylation status of endogenous and transgenic promoter and enhancer elements indicates that the internal promoter is not regulated in a manner similar to that of the MLC1 promoter or the downstream enhancer. A GATA protein consensus sequence in the proximal MLC3 promoter but not the MLC1 promoter binds with high affinity to GATA-4, a cardiac muscle- and gut-specific transcription factor. Mutation of either the MEF2 or GATA motifs in the MLC3 promoter attenuates its activity in both heart and skeletal muscles, demonstrating that MLC3 expression in these two diverse muscle types is dependent on common regulatory elements
Global Analysis of Dynamic Epigenetic Marking and Transcriptional Regulation Underlying T-Cell Lineage Commitment
No full textT-cell lineage specification and commitment success depends on precise temporal induction of T-lineage specific genes, as well as repression of lineage-inappropriate programs. After entry into the thymus, T-cell progenitors still retain inherited lineage plasticity, reflected by the mixed-lineage pattern of gene expression and the abilities to give rise to alternative lineages. Although Notch-Delta signaling is an essential force to trigger and sustain T-lineage differentiation, it does not appear to be the only requirement for this process. Successful commitment also depends on additional transcription factors, which often cooperatively interact with Notch-Delta signaling. However, the molecular mechanism by which pro-T cells are advanced to become committed T cells, in particular how the alternative lineage potentials are eliminated, is not fully understood. Using the genome-wide high-throughput sequencing, we track global shifts in gene expression pattern and transcriptional activity associated histone modifications in five successive stages of T-cell differentiation that span the commitment process. Our results show that T-lineage commitment is defined by the surprisingly complex downregulation of progenitor- and/or alternative lineage-associated programs, with relatively few regulatory genes are substantially upregulated. Rather than being silenced by a single global repression event, progenitor- and/or alternative lineage-associated genes are regulated by individual gene-specific mechanisms, indicated by the unsynchronized epigenetic transformations at discrete cis-elements of genes loci linked to progenitor and/or alternative lineage programs. We also investigate the genome-wide occupancies of PU.1 and GATA-3, two regulatory factors that have critical but complementary roles in early T-cell development. Binding sites choices of these two factors imply that transcriptional regulation by one particular factor is developmental context as well as dosage dependent. Furthermore, We combine this genome-wide approach with gene perturbation to study the function of Bcl11b, a transcription factor required for the completion of T-cell lineage commitment. Our analyses reveal that, in part through directly or indirectly regulation of Notch1 and GATA-3, Bcl11b mediates the modulation of T-cell lineage specification and commitment
Modelling Down Syndrome leukaemia using transchromosomic ES cell lines.
No full textPhDAMKL (acute megakaryoblastic leukaemia) accounts for at least 50% of all
cases of acute myeloid leukaemia (AML) associated with Down Syndrome
(DS).
Every tenth neonate with DS develops Transient Myeloproliferative Disorder
(TMD), a self-regressing neoplasia with features that closely resemble AMKL.
Despite the vast majority of TMD cases self-regressing within a few weeks,
approximately 30% of DS infants with TMD develop by the age of 2-4 years a
more aggressive, full-blown AMKL. Both DS-TMD and DS-AMKL are
associated with trisomy of human chromosome 21 (HSA21) and with acquired
mutations of GATA-1 (a transcription factor essential for
erythroid/megakaryocytic lineage specification) leading to the exclusive
production of a short form of the protein known as GATA-1s. Additional
molecular events involved in the progression from TMD to AMKL remain
largely unknown.
The aim of this project was to shed new light on the critical events involved in
the pathogenesis of DS-TMD and AMKL utilizing an innovative in vitro model
that mimics Down syndrome, a murine embryonic stem cell line carrying an
extra copy of human chromosome 21 (HSA21).
Using this transchromosomic ES cell system, I explored the effect of trisomy
21 (t21) on the generation of megakaryocytes in vitro, and showed that
trisomic megakaryocyte precursors display increased levels of GATA-1
compared to euploid controls and exhibit the tendency of forming macroscopic
colonies without overt GATA1 mutations. Furthermore, I genetically
manipulated the transchromosomic ES cell system by retrovirally
4
overexpressing GATA1s and demonstrated that trisomy 21 is required for
GATA-1s to exert its full hyperproliferative potential.
The influence of the supernumerary HSA21 on the ontogenesis of
haematopoietic stem cells (HSCs) from mesodermal precursors was also
studied in the transchromosomic system. In this thesis, I present evidence that
mesodermal colonies derived from transchromosomic ES cells give rise to an
increased number of immature haematopoietic progenitors compared to
euploid controls. I demonstrate that at least two independent genes on HSA21
contribute to this effect, and that trisomy of RUNX-1 (a master regulator of
primitive haematopoiesis encoded on chromosome 21) is required for an
increased haematopoietic commitment from the mesodemal precursors.
This thesis shows that t21 influences haematopoiesis (in general) and the
megakaryocytic lineage (in particular) at several levels and that it is
responsible for an overall increase in levels of immature cells that are targets
for acquisition of further leukaemogenic mutations.
Finally, in this study I clarify the role of JAK3, a gene whose mutations have
been reported in AMKL, in the progression from TMD to AMKL
Transcriptional regulation of the human ALDH1A1 promoter by the oncogenic homeoprotein TLX1/HOX11
No full textThe homeoprotein TLX1, which is essential to spleen organogenesis and oncogenic when aberrantly expressed in immature T cells, functions as a bifunctional transcriptional regulator, being capable of activation or repression depending on cell type and/or promoter context. However, the detailed mechanisms by which it regulates the transcription of target genes such as ALDH1A1 remains to be elucidated. We therefore functionally assessed the ability of TLX1 to regulate ALDH1A1 expression in two hematopoietic cell lines, PER-117 T-leukemic cells and human erythroleukemic (HEL) cells, by use of luciferase reporter and mobility shift assays. We showed that TLX1 physically interacts with the general transcription factor TFIIB via its homeodomain, and identified two activities in respect to TLX1-mediated regulation of the CCAAT box-containing ALDH1A1 promoter. The first involved CCAAT-dependent transcriptional repression via perturbation of GATA factor-containing protein complexes assembled at a non-canonical TATA (GATA) box. A structurally intact homeodomain was essential for repression by TLX1 although direct DNA binding was not required. The second activity, which involved CCAAT-independent transcriptional activation did not require an intact homeodomain, indicating that the activation and repression functions of TLX1 are distinct. These findings confirm ALDH1A1 gene regulation by TLX1 and support an indirect model for TLX1 function, in which protein-protein interactions, rather than DNA binding at specific sites, are crucial for its transcriptional activity
Function of Gata-2 in thymic epithelial cells : a transcription factor identified from gene expression analysis of endodermal cells committed to thymic epithelial cell fate
No full textThe thymus structure composes of clear morphological regions. The T-cell precursors enter the thymus in the cortico-medullary junction and migrate through the cortex towards the sub capsular region and back through to the cortex into the medulla. During this migration process the thymic epithelial cells provide the microenvironment for the maturation and selection of the majority of the peripheral T-cells. The thymic epithelial cells have their origin in the endodermal cells of the ventral aspect of the 3rd pharyngeal pouch while endodermal cells of the dorsal aspect of the 3rd pharyngeal pouch give rise to the parathyroid glands. For a better understanding of genes which might be involved in determination of endodermal cells to the thymic epithelial cell fate, the gene expression profile of the ventral aspect of 3rd pharyngeal pouch was compared to the dorsal aspect of 3rd pharyngeal pouch using microarrays. The analysis revealed 69 genes which were up regulated in the ventral aspect of 3rd pharyngeal pouch. Eleven genes with the largest differential expression values were further assessed (Gata-2, dll-1, C1qdc2, Samd5, Msx2, Msx1, Ehox, Tgfbi, Unc5c, FoxG1, 1110006E14Rik) using RT-PCR and whole mount in situ hybridization. The genes dll-1, Tgfbi, Msx1 and Msx2 are involved in the Notch, Tgf? and Bmp pathways, respectively. All these pathways are associated with thymus development. The role of the genes Ehox, Gata-2, C1qdc2, Samd5 and Unc5c in thymus development is so far undefined.
Gata-2, a transcription factor, known to be involved in hematopoiesis, was the only gene of which its expression was detected by gene chip data, RT-PCR and whole mount in situ hybridization. These results identified Gata-2 as a novel candidate that might be involved in the thymic epithelial cell development. To characterize the function of Gata-2 in thymus development, Gata-2 was specifically deleted in thymic epithelial cells using Foxn1-Cre. The thymi of 3, 6, 13, and 25 weeks old mice were removed and detailed studies were performed. FACS analysis of these thymi revealed an increased thymus cellularity in DN1-DN4, CD4, and CD8 in 6 weeks old thymi and onwards. The thymus architecture which was analyzed by H&E and immunohistochemistry (UEA-1, CK8, CK18, ERTR7) was unaffected when Gata-2 was deleted in TECs. The assessment of TEC population of Gata-2 KO mice did not show any difference. But the gene expression analysis of Gata-2 deficient TECs for the genes c-Jun, CXCL-12, CCL-25, IL-7, c-Fos, c-kit ligand, Edn-1, Edn-Ra, und Edn-Rb showed that CXCL-12 and c-kit ligand were higher expressed. CXCL-12 is involved in homing of T-cell precursors while c-kit L is involved in survival and proliferation of T-cell precursors. 7
In conclusion, Gata-2 might negatively regulate the transcription of CXCL-12 and c-kit ligand. A lack of Gata-2 expression in thymic epithelial cells, therefore, might lead to an increased T-cell precursor attraction and survival/proliferation, thus, explaining the higher cellularity observed in thymus of Gata-2 deficient mice
Role transkripčních faktorů PU.1 a GATA-1 v leukemické diferenciaci
No full textHematopoéza neboli krvetvorba je proces regulovaný transkripčními faktory, mezi nimiž hrají klíčovou roli molekuly PU.1 (Spi1, Sfpi1) a GATA-1. GATA-1 a PU.1 se mohou na DNA vzájemně vázat a blokovat tím své transkripční programy. Myší erytroleukemické buňky (MEL) jsou transformované erythroidní prekurzory zablokované v pokročilejším stádiu erythroidní diferenciace, současně exprimují PU.1 i GATA-1 a lze u nich navodit erytroidní diferenciaci snížením hladiny PU.1 či zvýšení hladiny GATA-1 v jádře. Ve své práci ukazuji, že v MEL buňkách je PU.1 dependentní transkriptom negativně regulovaný pomocí GATA-1. Tuto represi a následně možnou derepresi podrobněji popisuji na genech Cebpa a Cbfb, které kódují další důležité hematopoetické transkripční faktory. Pomocí chromatinové imunoprecipitace a reportérových esejí jsme identifikovali vazebné sekvence DNA pro vazbu PU.1 na genech Cebpa a Cbfb, na nichž jsme v leukemických blastech detekovali současně faktory PU.1 i GATA-1. Regulace transkripce těchto genů manipulací hladiny PU.1 a GATA-1 zahrnuje kvantitativní změny úrovně acetylace H3K9, známky transkripčně aktivního chromatinu. Data jsou podpořena experimenty ukazujícími, že signifikantní derepresi genů Cebpa a Cbfb lze v MEL buňkách dosáhnout jak aktivací PU.1, tak i inaktivací GATA-1. Má disertační práci...Hematopoiesis is coordinated by a complex regulatory network of transcription factors among them PU.1 (Spi1, Sfpi1) and GATA-1 represent key molecules. GATA-1 and PU.1 bind each other on DNA to block each others transcriptional programs to prevent development of undesired lineage during hematopoietic commitment. Murine erythroleukemia (MEL) cells, transformed erythroid precursors that are blocked from completing the late stages of erythroid differentiation, co-express GATA-1 and PU.1 and as my and others data document, are able to respond to molecular removal (down-regulation) of PU.1 or addition (up-regulation) of GATA-1 by inducing terminal erythroid differentiation. We provide novel evidence that downregulation of GATA-1 or upregulation of PU.1 induces incompletely differentiation into cell cycle arrested monocytic-like cells. Furthermore, PU.1- dependent transcriptome is negatively regulated by GATA-1 in MEL cells, including CCAAT/enhancer binding protein alpha (Cebpa) and Core-binding factor, beta subunit (Cbfb) that encode additional key hematopoietic transcription factors. Chromatin immunoprecipitation and reporter assays identified PU.1 motif sequences near Cebpa and Cbfb that are co-occupied by PU.1 and GATA-1 in the leukemic blasts. Furthermore, transcriptional regulation of these loci by...Ústav patologické fyziologie 1. LF UKInstitute of Pathological Physiology First Faculty of Medicine Charles UniversityFirst Faculty of Medicine1. lékařská fakult
- …
