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alpha-Globin genes: thalassemic and structural alterations in a Brazilian population

Wenning,M.R.S.C.; Kimura,E.M.; Costa,F.F.; Saad,S.T.O.; Gervásio,S.; de Jorge,S.B.; Borges,E.; Silva,N.M.; Sonati,M.F.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2000 EN
Relevância na Pesquisa
56.28%
Seven unrelated patients with hemoglobin (Hb) H disease and 27 individuals with alpha-chain structural alterations were studied to identify the alpha-globin gene mutations present in the population of Southeast Brazil. The -alpha3.7, --MED and -(alpha)20.5 deletions were investigated by PCR, whereas non-deletional alpha-thalassemia (alphaHphalpha, alphaNcoIalpha, aaNcoI, alphaIcalpha and alphaTSaudialpha) was screened with restriction enzymes and by nested PCR. Structural alterations were identified by direct DNA sequencing. Of the seven patients with Hb H disease, all of Italian descent, two had the -(alpha)20.5/-alpha3.7 genotype, one had the --MED/-alpha3.7 genotype, one had the --MED/alphaHphalpha genotype and three showed interaction of the -alpha3.7 deletion with an unusual, unidentified form of non-deletional alpha-thalassemia [-alpha3.7/(aa)T]. Among the 27 patients with structural alterations, 15 (of Italian descent) had Hb Hasharon (alpha47Asp->His) associated with the -alpha3.7 deletion, 4 (of Italian descent) were heterozygous for Hb J-Rovigo (alpha53Ala->Asp), 4 (3 Blacks and 1 Caucasian) were heterozygous for Hb Stanleyville-II (alpha78Asn->Lys) associated with the alpha+-thalassemia...

Screening for mutations in human alpha-globin genes by nonradioactive single-strand conformation polymorphism

Jorge,S.B.; Melo,M.B.; Costa,F.F.; Sonati,M.F.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2003 EN
Relevância na Pesquisa
66.43%
Point mutations and small insertions or deletions in the human alpha-globin genes may produce alpha-chain structural variants and alpha-thalassemia. Mutations can be detected either by direct DNA sequencing or by screening methods, which select the mutated exon for sequencing. Although small (about 1 kb, 3 exons and 2 introns), the alpha-globin genes are duplicate (alpha2 and alpha1) and highy G-C rich, which makes them difficult to denature, reducing sequencing efficiency and causing frequent artifacts. We modified some conditions for PCR and electrophoresis in order to detect mutations in these genes employing nonradioactive single-strand conformation polymorphism (SSCP). Primers previously described by other authors for radioactive SSCP and phast-SSCP plus denaturing gradient gel electrophoresis were here combined and the resultant fragments (6 new besides 6 original per alpha-gene) submitted to silver staining SSCP. Nine structural and one thalassemic mutations were tested, under different conditions including two electrophoretic apparatus (PhastSystem™ and GenePhor™, Amersham Biosciences), different polyacrylamide gel concentrations, run temperatures and denaturing agents, and entire and restriction enzyme cut fragments. One hundred percent of sensitivity was achieved with four of the new fragments formed...

Investigating alpha-globin structural variants: a retrospective review of 135,000 Brazilian individuals

Kimura,Elza Miyuki; Oliveira,Denise Madureira; Jorge,Susan Elisabeth; Ribeiro,Daniela Maria; Zaccariotto,Tânia Regina; Santos,Magnun Nueldo Nunes; Almeida,Vanessa; Albuquerque,Dulcinéia Martins; Costa,Fernando Ferreira; Sonati,Maria de Fátima
Fonte: Associação Brasileira de Hematologia e Hemoterapia e Terapia Celular Publicador: Associação Brasileira de Hematologia e Hemoterapia e Terapia Celular
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2015 EN
Relevância na Pesquisa
56.38%
Background: Brazil has a multiethnic population with a high diversity of hemoglobinopathies. While screenings for beta-globin mutations are far more common, alterations affecting alpha-globin genes are usually more silent and less well known. The aim of this study was to describe the results of a screening program for alpha-globin gene mutations in a representative sample of the Southeastern Brazilian population. Methods: A total of 135,000 individuals, including patients with clinical suspicion of hemoglobinopathies and their family members, randomly chosen individuals submitted to blood tests and blood donors who were abnormal hemoglobin carriers were analyzed. The variants were screened by alkaline and acid electrophoreses, isoelectric focusing and cation-exchange high performance liquid chromatography (HPLC) and the abnormal chains were investigated by reverse-phase high performance liquid chromatography (RP-HPLC). Mutations were identified by molecular analyses, and the oxygen affinity, heme-heme cooperativity and Bohr effect of the variants were evaluated by functional tests. Results: Four new and 22 rare variants were detected in 98 families. Some of these variants were found in co-inheritance with other hemoglobinopathies. Of the rare hemoglobins...

The expression of human α-like globin genes in transgenic mice mediated by bacterial artificial chromosome

Feng, Dong-Xiao; Liu, De-Pei; Huang, Yue; Wu, Lin; Li, Tie-Chang; Wu, Min; Tang, Xiao-Bin; Liang, Chih-Chuan
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.57%
After screening a bacterial artificial chromosome of human genomic DNA library with human HS-40, ζ-, α-, and θ-globin probes, a 110-kb clone bearing the whole human α-globin gene cluster was obtained and rare restriction endonuclease mapping was performed. The bacterial artificial chromosome DNA was isolated, and transgenic mice were generated. Three founders were detected from 35 newborn mice. The copy numbers were 1, 2, and 2, and the expression of human α-globin genes in various tissues at different developmental stages in the transgenic mice was assayed. The human α-globin mRNA can be detected in bone marrow, kidney, liver, brain, but not in muscle, testis, or thymus. The human ζ-globin genes were switched off, and the α-globin genes were switched at day 11.5 in mouse embryo, indicating that developmental stage-specific expression of the α-like globin genes was properly regulated. The human α-globin mRNA ranged between 17–68% of the endogenous mouse α-globin, suggesting that the expression of human α-globin genes is integration site-dependent in transgenic mice. The ratio of human α2- and α1-globin gene expression in adult transgenic mouse is about 2.5:1 similar to the expression in human.

Activation of human beta-globin genes from nonerythroid cells by fusion with murine erythroleukemia cells.

Pyati, J; Kucherlapati, R S; Skoultchi, A I
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1980 EN
Relevância na Pesquisa
46.58%
A human beta-globin gene derived from an established human lymphoblast cell line was introduced into murine erythroleukemia (MEL) cells by cell fusion. The globin genes in MEL cells are inducible by dimethyl sulfoxide (Me2SO); induction leads to the accumulation of mouse globin mRNA and hemoglobin. Globin mRNA was not detected in the cytoplasm of the human lymphoblast cells, even at low levels, whether or not these cells were treated with Me2SO. In cell hybrids that had retained the lymphoblast-derived beta-globin gene, human beta-globin mRNA was induced by Me2SO. Poly(A)-containing 10S human beta-globin mRNA was detected in the cytoplasm of the hybrid cells. Karyologic and isozymic analyses of a series of hybrids and subclones showed that human beta-globin gene expression occurred only in hybrids that had retained human chromosome 11. Analysis of one hybrid bearing a deletion of both the beta-globin and lactate dehydrogenase A genes indicated that the beta-globin gene is located on the short arm of human chromosome 11. No other human chromosomes are required for human beta-globin gene expression in MEL cell hybrids. We conclude that the restricted expression of a globin gene in a human nonerythroid cell can be reversed. Furthermore...

Regulated expression of human alpha- and beta-globin genes in transient heterokaryons.

Baron, M H; Maniatis, T
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1991 EN
Relevância na Pesquisa
46.59%
We have examined the expression of human alpha- and beta-like globin genes in transient heterokaryons formed by fusion of human nonerythroid cells with terminally differentiating mouse erythroleukemia (MEL) cells or with a MEL cell variant (GM979) in which the endogenous mouse embryonic beta-globin genes are activated. In both the parental MEL cells and the heterokaryons, the alpha-globin genes were activated at least 12 h earlier than the embryonic, fetal, and adult beta-globin genes. These results suggest that kinetic differences in the activation of alpha- and beta-like globin genes are not simply the result of different rates of accumulation of erythroid-specific regulatory factors but may reflect differences in the mechanisms governing the transcriptional activation of these genes during erythroid cell differentiation. In mouse GM979 x human nonerythroid heterokaryons, the human embryonic beta-globin gene was activated, consistent with our previous demonstration that erythroid cells contain stage-specific trans-acting regulators of globin gene expression. Moreover, a dramatic increase in the ratio of human fetal to adult beta-globin transcription was observed compared with that seen in MEL-human nonerythroid hybrids. This ratio change may reflect competition between the fetal and adult beta-globin genes for productive interactions with erythroid cell-specific regulatory elements. Finally...

Genomic evidence for independent origins of β-like globin genes in monotremes and therian mammals

Opazo, Juan C.; Hoffmann, Federico G.; Storz, Jay F.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.57%
Phylogenetic reconstructions of the β-globin gene family in vertebrates have revealed that developmentally regulated systems of hemoglobin synthesis have been reinvented multiple times in independent lineages. For example, the functional differentiation of embryonic and adult β-like globin genes occurred independently in birds and mammals. In both taxa, the embryonic β-globin gene is exclusively expressed in primitive erythroid cells derived from the yolk sac. However, the “ε-globin” gene in birds is not orthologous to the ε-globin gene in mammals, because they are independently derived from lineage-specific duplications of a proto β-globin gene. Here, we report evidence that the early and late expressed β-like globin genes in monotremes and therian mammals (marsupials and placental mammals) are the products of independent duplications of a proto β-globin gene in each of these two lineages. Results of our analysis of genomic sequence data from a large number of vertebrate taxa, including sequence from the recently completed platypus genome, reveal that the ε- and β-globin genes of therian mammals arose via duplication of a proto β-globin gene after the therian/monotreme split. Our analysis of genomic sequence from the platypus also revealed the presence of a duplicate pair of β-like globin genes that originated via duplication of a proto β-globin gene in the monotreme lineage. This discovery provides evidence that...

All of the human β-type globin genes compete for LCR enhancer activity in embryonic erythroid cells of yeast artificial chromosome transgenic mice

Okamura, Eiichi; Matsuzaki, Hitomi; Campbell, Andrew D.; Engel, James Douglas; Fukamizu, Akiyoshi; Tanimoto, Keiji
Fonte: The Federation of American Societies for Experimental Biology Publicador: The Federation of American Societies for Experimental Biology
Tipo: Artigo de Revista Científica
Publicado em /12/2009 EN
Relevância na Pesquisa
46.6%
In primitive erythroid cells of human β-globin locus transgenic mice (TgM), the locus control region (LCR)-proximal ε- and γ-globin genes are transcribed, whereas the distal δ- and β-globin genes are silent. It is generally accepted that the β-globin gene is competitively suppressed by γ-globin gene expression at this developmental stage. Previously, however, we observed that ε-globin gene expression was severely attenuated when its distance from the LCR was extended, implying that β-globin gene might also be silenced because of its great distance from the LCR. Here, to clarify the β-globin gene silencing mechanism, we established TgM lines carrying either γ- or ε- plus γ-globin promoter deletions, without significantly altering the distance between the β-globin gene and the LCR. Precocious expression of δ- and β-globin genes was observed in primitive erythroid cells of mutant, but not wild-type TgM, which was most evident when both the ε and γ promoters were deleted. Thus, we clearly demonstrated that the repression of the δ- and β-globin genes in primitive erythroid cells is dominated by competitive silencing by the ε- and γ-globin gene promoters, and that ε- and the other β-like globin genes might be activated by two distinct mechanisms by the LCR.—Okamura...

Transcription Factors KLF1 and KLF2 Positively Regulate Embryonic and Fetal β-Globin Genes through Direct Promoter Binding*

Alhashem, Yousef N.; Vinjamur, Divya S.; Basu, Mohua; Klingmüller, Ursula; Gaensler, Karin M. L.; Lloyd, Joyce A.
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.57%
Krüppel-like factors (KLFs) control cell differentiation and embryonic development. KLF1 (erythroid Krüppel-like factor) plays essential roles in embryonic and adult erythropoiesis. KLF2 is a positive regulator of the mouse and human embryonic β-globin genes. KLF1 and KLF2 have highly homologous zinc finger DNA-binding domains. They have overlapping roles in embryonic erythropoiesis, as demonstrated using single and double KO mouse models. Ablation of the KLF1 or KLF2 gene causes embryonic lethality, but double KO embryos are more anemic and die sooner than either single KO. In this work, a dual human β-globin locus transgenic and KLF knockout mouse model was used. The results demonstrate that the human ϵ- (embryonic) and γ-globin (fetal) genes are positively regulated by KLF1 and KLF2 in embryos. Conditional KO mouse experiments indicate that the effect of KLF2 on embryonic globin gene regulation is at least partly erythroid cell-autonomous. KLF1 and KLF2 bind directly to the promoters of the human ϵ- and γ-globin genes, the mouse embryonic Ey- and βh1-globin genes, and also to the β-globin locus control region, as demonstrated by ChIP assays with mouse embryonic blood cells. H3K9Ac and H3K4me3 marks indicate open chromatin and active transcription...

The hematopoietic regulator TAL1 is required for chromatin looping between the β-globin LCR and human γ-globin genes to activate transcription

Yun, Won Ju; Kim, Yea Woon; Kang, Yujin; Lee, Jungbae; Dean, Ann; Kim, AeRi
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.58%
TAL1 is a key hematopoietic transcription factor that binds to regulatory regions of a large cohort of erythroid genes as part of a complex with GATA-1, LMO2 and Ldb1. The complex mediates long-range interaction between the β-globin locus control region (LCR) and active globin genes, and although TAL1 is one of the two DNA-binding complex members, its role is unclear. To explore the role of TAL1 in transcription activation of the human γ-globin genes, we reduced the expression of TAL1 in erythroid K562 cells using lentiviral short hairpin RNA, compromising its association in the β-globin locus. In the TAL1 knockdown cells, the γ-globin transcription was reduced to 35% and chromatin looping of the Gγ-globin gene with the LCR was disrupted with decreased occupancy of the complex member Ldb1 and LMO2 in the locus. However, GATA-1 binding, DNase I hypersensitive site formation and several histone modifications were largely maintained across the β-globin locus. In addition, overexpression of TAL1 increased the γ-globin transcription and increased interaction frequency between the Gγ-globin gene and LCR. These results indicate that TAL1 plays a critical role in chromatin loop formation between the γ-globin genes and LCR, which is a critical step for the transcription of the γ-globin genes.

The Formation and function of chromatin domains at the murine beta globin locus

Fromm, George John ; Bulger, Michael
Fonte: Universidade de Rochester Publicador: Universidade de Rochester
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
46.6%
Thesis (Ph. D.)--University of Rochester. School of Medicine and Dentistry. Dept. of Biochemistry and Biophysics, 2009.; The eukaryotic genome condenses within the nucleus to form chromatin, which can interfere with the interaction between the transcriptional machinery and genomic DNA. Several genetic and epigenetic mechanisms have evolved with chromatin structure to overcome this obstacle, in order to facilitate selective gene expression, often in a developmental- and/or tissue-specific context. This includes the covalent modification of the histone amino-terminal tails; for example the acetylation and methylation of lysine residues. Active gene promoters are almost universally associated with acetylated histones, facilitating the decondensation of chromatin and stabilizing the binding of transcription factors. For the vast majority of active genes, these histone modifications localize to the promoter. At the β-globin locus and several other loci, however, histone hyperacetylation extends beyond the promoter, over tens of kilobases; we term such patterns of histone modifications "hyperacetylated domains". Little is known of either the mechanism by which these domains form or their function. The murine β-globin genes are expressed in erythroid cells in a developmental-specific fashion. Primitive erythroid cells originate in the yolk sac blood islands and primarily express the embryonic ey- and βh1- globin genes. Upon the developmental switch to definitive erythropoiesis in the fetal liver...

Rôle du facteur de transcription BP1 dans la régulation des gènes du locus humain de beta-globine

Ah-Son, Nicolas
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
46.59%
Le facteur de transcription BP1 humain est exprimé dans les cellules érythroïdes pendant le développement fœtal mais son niveau d’expression est réduit au stade adulte. Les études antérieures in vitro ont montré que BP1 est un répresseur du gène adulte de β-globine mais sa fonction dans la régulation des gènes ε et γ n’a pas été abordée à ce jour. Dans notre étude, nos analyses de BP1 humain ont été menées in vivo au stade embryonnaire en utilisant une lignée de souris transgénique surexprimant BP1 dans les cellules érythroïdes définitives murines. Au niveau protéique, BP1 humain est exprimé aux âges E12.5 et E13.5 dans les cellules érythroïdes fœtales des embryons transgéniques. Toutefois, les niveaux de BP1 humain ne perturbent pas l’érythropoïèse définitive fœtale: les embryons transgéniques ne sont pas anémiques et ne meurent pas in utero. La surexpression de BP1 humain altère tout de même le niveau endogène des facteurs de transcription Ikaros et SOX6 impliqués dans la régulation des gènes de β-globine durant l’érythropoïèse définitive fœtale murine. Chez les embryons doubles transgéniques exprimant BP1 et les gènes humains de β-globine à E12.5, l’expression du gène adulte β est réduite alors que celle des gènes ε et γ est non réprimée. Les mesures d’expression des gènes humains de β-globine effectuées en absence d’Ikaros à E12.5 précisent le rôle de BP1 humain dans l’activation du gène embryonnaire ε. Dans les cellules érythroïdes fœtales murines dépourvues d’Ikaros à E12.5...

Molecular biology and evolution of beta-globin genes in monotremes / Mi-Hye Lee.; Molecular biology and evolution of beta-globin genese in monotremes

Lee, Mi-Hye
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 93916 bytes; application/pdf
Publicado em //1997 EN
Relevância na Pesquisa
66.33%
The evolutionary relationships of the beta-like globin genes were studied by applying maximum parsimony methods to aligned DNA sequences.; Thesis (Ph.D.)--University of Adelaide, Dept. of Genetics, 1998?; Erratum pasted on front fly-leaf.; Bibliography: leaves 180-202.; xvii, 220 leaves : ill. (some col.) ; 30 cm.; Title page, contents and abstract only. The complete thesis in print form is available from the University Library.

The globin genes of the tammar wallaby ; David Wheeler.

Wheeler, David William
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 170859 bytes; application/pdf
Publicado em //2003 EN
Relevância na Pesquisa
66.52%
"In the study reported in this thesis, a PCR-based approach was used to isolate the b-like globin genes that are present in the tammar wallaby, Macropus eugenii, including the gene that encodes the w-globin chain. Three -like globin genes (b-, e-, w-) that had previously been described at the protein level in the tammar wallaby were characterised. w-globin orthologues were also identified in a wide range of marsupial species, and in one of these species, the dunnart (Sminthopsis crassicaudata), the complete DNA sequence of the w-globin gene was determined. Southern analysis in the dunnart and in situ hybridisation in the tammar wallaby, provided evidence for the unexpected conclusion that w-globin is not part of the -globin gene cluster in these species. RT-PCR studies using RNA isolated from a new-born dunnarts confirmed that w-globin is expressed in this species. Therefore, this is the first report of an "orphaned" b-like globin gene that is expressed in a vertebrate." --p. 6.; Thesis (Ph.D.)--University of Adelaide, Dept. of Molecular Biosciences, 2003; "January 2003"; Addendum on back page.; Bibliography: p. 175-184.; 184 p. : ill. (some col.) ; 30 cm.; Title page, contents and abstract only. The complete thesis in print form is available from the University Library.

Novel and rare large deletions in the globin gene clusters causing different types of thalassemia

Coelho, Andreia; Fernandes, Emília; Batalha-Reis, Ana; Sonesson, Annika; Picanço, Isabel; Miranda, Armandina; Faustino, Paula
Fonte: Instituto Nacional de Saúde Doutor Ricardo Jorge, IP Publicador: Instituto Nacional de Saúde Doutor Ricardo Jorge, IP
Tipo: Conferência ou Objeto de Conferência
Publicado em /11/2011 ENG
Relevância na Pesquisa
56.5%
The major component of the red blood cells is hemoglobin A which consists of 2α- and 2β-globin chains encoded by α- and β-globin genes located in two different gene clusters (16p13.3 and 11p.15.5, respectively). Molecular defects (usually point mutation or short deletion) that give rise to a quantitative reduction of the corresponding globin chain, result in a hereditary hypochromic and microcytic anemia called thalassemia. However, rarely, the molecular basis of the pathology could be a large deletion affecting several globin genes and/or their distal regulatory sequence. Four patients with hematological phenotypes suggestive of thalassemia, in whom no globinic molecular abnormalities had been found by standard diagnostic procedures, were screened for deletions in the telomeric region of chromosome 16 and 11, by Multiplex Ligation-dependent Probe Amplification (MLPA) assay. To further characterize the breakpoints of the deletions found, we employed synthetic MLPA probemixes designed in our laboratory, as well as PCR and DNA sequencing. We identified two cases of α-thalassemia caused by two distinct large deletions which remove all α-like structural genes and their distal regulatory sites: both are telomeric, one presents at least 271.14 kb of length and the other...

Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals

Patel, V.; Cooper, S.; Deakin, J.; Fulton, B.; Graves, T.; Warren, W.; Wilson, R.; Graves, J.
Fonte: BioMed Central Ltd. Publicador: BioMed Central Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
46.62%
Background: Vertebrate alpha (α)- and beta (β)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the α- and β-globin clusters expanded, and then were separated onto different chromosomes. The previous finding of a fossil β-globin gene (ω) in the marsupial α-cluster, however, suggested that duplication of the α-β cluster onto two chromosomes, followed by lineage-specific gene loss and duplication, produced paralogous α- and β-globin clusters in birds and mammals. Here we analyse genomic data from an egg-laying monotreme mammal, the platypus (Ornithorhynchus anatinus), to explore haemoglobin evolution at the stem of the mammalian radiation. Results: The platypus α-globin cluster (chromosome 21) contains embryonic and adult α- globin genes, a β-like ω-globin gene, and the GBY globin gene with homology to cytoglobin, arranged as 5'-ζ-ζ'-αD-α3-α2-α1-ω-GBY-3'. The platypus β-globin cluster (chromosome 2) contains single embryonic and adult globin genes arranged as 5'-ε-β-3'. Surprisingly, all of these globin genes were expressed in some adult tissues. Comparison of flanking sequences revealed that all jawed vertebrate α-globin clusters are flanked by MPG-C16orf35 and LUC7L...

Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals

Patel, Vidushi; Deakin, Janine; Graves, Jennifer; Cooper, Steven; Fulton, Bob; Graves, Tina; Warren, Wesley; Wilson, Richard K
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Artigo de Revista Científica Formato: 22 pages
Relevância na Pesquisa
46.62%
BACKGROUND: Vertebrate alpha (α)- and beta (β)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the α- and β-globin clusters expanded, and then were separated onto different chromosomes. The previous finding of a fossil β-globin gene (ω) in the marsupial α-cluster, however, suggested that duplication of the α-β cluster onto two chromosomes, followed by lineage-specific gene loss and duplication, produced paralogous α- and β-globin clusters in birds and mammals. Here we analyse genomic data from an egg-laying monotreme mammal, the platypus (Ornithorhynchus anatinus), to explore haemoglobin evolution at the stem of the mammalian radiation. RESULTS: The platypus α-globin cluster (chromosome 21) contains embryonic and adult α- globin genes, a β-like ω-globin gene, and the GBY globin gene with homology to cytoglobin, arranged as 5'-ζ-ζ'-αD-α3-α2-α1-ω-GBY-3'. The platypus β-globin cluster (chromosome 2) contains single embryonic and adult globin genes arranged as 5'-ε-β-3'. Surprisingly, all of these globin genes were expressed in some adult tissues. Comparison of flanking sequences revealed that all jawed vertebrate α-globin clusters are flanked by MPG-C16orf35 and LUC7L...

Mecanismos reguladores da sintese de globinas : avaliação funcional da região R/PYR e analise da expressão genica diferencial na persistencia hereditaria de hemoglobina fetal e na delta-beta talassemia; Regulatory mechanisms of globin syntheis : functional evaluation of R/PYR region and differential gene expression analysis in hereditary persistence of etal hemoglobin and delta-beta thalassemia

Tiago Gomes de Andrade
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 08/02/2006 PT
Relevância na Pesquisa
46.58%
Persistência Hereditária de Hemoglobina Fetal (PHHF) consiste num grupo heterogêneo de alterações hereditárias, sem manifestações clínicas significativas, onde ocorrem falhas na mudança perinatal normal de hemoglobina fetal para hemoglobina adulta, resultando em altos níveis de Hb F durante a vida adulta. Nos tipos delecionais ocorre normalmente aumento de ambas as cadeias, ? A e ? G, até 30%, estando associadas a deleções de seqüências de DNA dentro do grupo de genes ?. As (??)º - talassemias também se originam a partir de deleções, em muitos casos bastante similares às que originam as formas delecionais de PHHF, entretanto com níveis de Hb F aumentados em menor proporção (5-20%), sendo acompanhadas nos heterozigotos por hipocromia e microcitose nas hemácias. Três hipóteses principais foram propostas para explicar a relação destas deleções com a ausência de supressão normal dos genes ? na fase adulta: competição entre promotores pelo LCR (Locus Control Region); justaposição de elementos acentuadores, normalmente encontrados a 3' do cluster, nas proximidades dos genes ?; remoção de elementos silenciadores, localizados entre ? A e ?. Neste trabalho, realizamos estudos funcionais com uma região intergênica...

Quantitation of human gamma globin genes and gamma globin mRNA with purified gamma globin complementary DNA.

Ramirez, F; O'Donnell, J V; Natta, C; Bank, A
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1976 EN
Relevância na Pesquisa
46.56%
Complementary DNA (cDNA) specific for gamma-globin nucleotide sequences has been prepared by hybridizing total cDNA made from cord blood messenger RNA (mRNA) as template to an excess of normal adult human globin mRNA and recovering the single-stranded cDNA from hydroxylapatite. The specificity of the gamma cDNA for gamma mRNA sequences is strongly supported by the hybridization of this cDNA at low Cot values (Co, concentration of RNA and t, time in seconds) to RNA samples containing large amounts of functional gamma globin mRNA and the lack of hybridization to RNA samples containing little, if any, gamma-globin mRNA. The absence of cross-hybridization of gamma cDNA with alpha, beta, and delta mRNAs is demonstrated by the complete hybridization of the gamma cDNA to mRNA samples completely lacking either alpha or beta and delta mRNA. An estimate of the number of gamma-globin genes in human cellular DNA was obtained by hybridization of purified gamma cDNA to DNA from spleen and white blood cells of normal and beta-thalassemia subjects and measurement of the percent of gamma cDNA hybridized at saturation. The results indicate that there are between one and two gamma-globin genes per total haploid gene DNA equivalent obtained from both normal and beta-thalassemia subjects. These values are consistent with genetic evidence for the presence of multiple gamma gene loci in human cells. The finding that the number of gamma-globin genes in beta-thalassemia DNA is similar to that in nonthalassemia DNA indicates that a deletion of gamma-globin genes cannot account for either the inadequate gamma-globin synthesis or indirectly for the decreased or absent beta-globin synthesis in beta-thalassemia cells.

Stable transfer and expression of exogenous human globin genes in human erythroleukemia (K562) cells.

Young, K; Donovan-Peluso, M; Bloom, K; Allan, M; Paul, J; Bank, A
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1984 EN
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To study the expression of globin genes in human cells, human epsilon-globin genes were transferred into a K562 cell line, Bos, which synthesizes very low amounts of epsilon-globin mRNA. A plasmid (pSV2neo-epsilon) containing a complete epsilon-globin gene and 2 kilobases (kb) of 5' flanking DNA as well as a neomycin-resistance gene and a simian virus 40 origin of replication was transfected into Bos cells; the compound G418, a neomycin analogue, was used to select transformed cells. The presence of unique bands by DNA restriction analysis shows that 11 of 14 of the G418-resistant clones have at least one copy of an integrated epsilon-globin gene. RNA expression measured by RNA blotting shows significantly more epsilon-globin mRNA sequences than in untransfected Bos cells in 10 of 11 lines; in most lines, epsilon-globin mRNA was additionally increased in the presence of hemin. In two lines, epsilon-globin mRNA expression with hemin was comparable to that of a high epsilon-globin producing cell line, K562 clone 2. The one G418-resistant line without epsilon-globin genes had no epsilon-mRNA expression. The high epsilon-mRNA expression in several of the lines suggests that exogenous epsilon-globin genes with only 2-kb 5' flanking DNA may be sufficient to be appropriately expressed in these homologous erythroid cells. These results have implications for the potential success of transfer of normal human genes to human bone marrow cells as an approach to the treatment of inherited anemias.