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Abnormal methylation at the KvDMR1 imprinting control region in clinically normal children conceived by assisted reproductive technologies

GOMES, M. V.; HUBER, J.; FERRIANI, R. A.; AMARAL NETO, A. M.; RAMOS, E. S.
Fonte: OXFORD UNIV PRESS Publicador: OXFORD UNIV PRESS
Tipo: Artigo de Revista Científica
ENG
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56.56%
Genomic imprinting alterations have been shown to be associated with assisted reproductive technologies (ARTs) in animals. At present, data obtained in humans are inconclusive; however, some epidemiological studies have demonstrated an increased incidence of imprinting disorders in children conceived by ARTs. In the present study, we focused on the effect of ARTs [IVF and intracytoplasmic sperm injection (ICSI)] on the epigenetic reprogramming of the maternally methylated imprinting control region KvDMR1 in clinically normal children. Qualitative and quantitative methylation at KvDMR1 were assessed by the methylation-specific PCR approach and by the methylation-sensitive enzymatic digestion associated with real-time PCR method, respectively. DNA was obtained from peripheral blood of 12/18 and umbilical cord blood and placenta of 6/18 children conceived by IVF or ICSI. The methylation patterns observed in this group were compared with the patterns observed in 30 clinically normal naturally conceived children (negative controls) and in 3 naturally conceived Beckwith-Wiedemann syndrome patients (positive controls). Hypomethylation at KvDMR1 was observed in 3/18 clinically normal children conceived by ARTs (2 conceived by IVF and 1 by ICSI). A discordant methylation pattern was observed in the three corresponding dizygotic twins. Our findings corroborate the hypothesis of vulnerability of maternal imprinting to ARTs. Furthermore...

Estabilidade do controle epigenético em células humanas normais e transformadas; Stability of epigenetic control in normal and transformed human cells

Araújo, Érica Sara Souza de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 20/03/2012 PT
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46.77%
A epigenética aborda o controle da expressão gênica através de diversos fatores que agem sob a cromatina, os melhor estudados são a metilação do DNA e a acetilação em histonas, relacionadas à repressão e ativação gênica, respectivamente. Em mamíferos, existem dois fenômenos epigenéticos interessantes: a inativação do cromossomo X (ICX) em fêmeas, que garante o equilíbrio transcricional gênico entre os sexos, e o imprinting genômico, caracterizado pela expressão monoalélica dependente da origem parental. No presente estudo, propusemos verificar a manutenção do controle epigenético em células humanas normais e transformadas em condições semelhantes de hipometilação do DNA e hiperacetilação em histonas (após uso das drogas 5-aza-2-'deoxicitidina (5-aza-dC) e ácido valproico, respectivamente), através do monitoramento da expressão alelo-específica pelo uso de polimorfismos de única base presentes em regiões codificadoras. Em células normais houve manutenção da ICX e do imprinting genômico, enquanto que em células transformadas hipometiladas foram observadas indução de XIST, e perda de imprinting dos genes IGF2, H19 e PEG10. Observamos que ambas as drogas podem diminuir a expressão de DNMT1...

Estudo das Regiões Controladoras de Imprinting 1 e 2 em Oócitos, Embriões e Placentas de Primeiro Trimestre; Imprinting Control Regions 1 and 2 in Oocytes, Embryos and Early Placenta

Furtado, Cristiana Libardi Miranda
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 10/04/2012 PT
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56.64%
O imprinting genômico é um processo epigenético essencial para o desenvolvimento normal de mamíferos com placenta e refere-se à expressão gênica alelo-específica, de acordo com a origem parental. A expressão dos genes marcados por imprinting é controlada por regiões diferencialmente metiladas (DMRs), situadas em regiões controladoras de imprinting (ICRs). O cromossomo 29 de Bos taurus possui dois domínios cromossômicos semelhantes à região 11p15.5 de humanos, que são denominados KvDMR1 (na ICR2) e H19DMR (na ICR1). Essas ICRs controlam um cluster de genes importantes para o crescimento e desenvolvimento, sendo a KvDMR1 metilada no alelo materno e a e H19DMR metilada no alelo paterno. No presente trabalho, foi verificado o padrão de metilação da KvDMR1 e da H19DMR em oócitos não maturados (Vg) e maturados in vitro (MII) e nos blastocistos inicial (Bi) e expandido (Bx) bovinos e em placentas bovinas e humanas de primeiro trimestre. Foram coletados oócitos e embriões pré-implantação no estágio de blastocisto produzidos pela técnica de Fertilização in vitro. Também foram coletados o tecido placentário e de um feto bovino de 49 dias e de uma placenta humana, com idade gestacional de 12 semanas. O DNA genômico foi extraído e modificado com bissulfito de sódio. O padrão de metilação das regiões KvDMR1 e H19DMR foi verificado por meio de clonagem e seqüenciamento do DNA modificado com bissulfito de sódio. Para as análises de expressão gênica nos oócitos e blastocistos...

Influência da idade gestacional no perfil epigenético placentário; Influence of gestational age on placental epigenetic profile

Leite, Sarah Blima Paulino
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/09/2012 PT
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46.77%
O imprinting genômico, processo regulado epigeneticamente segundo o qual os genes se expressam de acordo com sua origem parental, está envolvido no crescimento e desenvolvimento placentário. Na região 11p15.5 encontram-se vários genes regulados por duas regiões controladoras de imprinting (ICR1 e ICR2), onde se encontram as regiões diferencialmente metiladas H19DMR e KvDMR1. Acredita-se que o padrão de imprinting seja dinamicamente regulado durante o desenvolvimento da placenta. Em humanos, há poucas informações sobre imprinting genômico e desenvolvimento placentário, principalmente para estágios precoces do desenvolvimento devido às dificuldades técnicas de obtenção dessas placentas. A descrição de mosaicismo do padrão de metilação restrito a placenta ou entre a placenta e o feto evidencia um perfil epigenético único deste órgão. A 5-hidroximetilação, a qual não tem um papel de silenciamento gênico, pode ser confundida com a metilação do DNA nas análises moleculares. O objetivo principal do presente estudo foi o de verificar a influência da idade gestacional (IG) no perfil de metilação do DNA das ICRs 1 e 2 em vilosidade coriônica, bem como a existência de mosaicismo do perfil de metilação intra-placentário. Neste trabalho também foi investigada a presença de hidroximetilação na KvDMR1. Foram coletadas amostras de tecido placentário...

Dissomia uniparental e mosaicismo somático como mecanismos de alterações epigenéticas do imprinting genômico; Uniparental disomy and somatic mosaicism: mechanisms for epigenetic deregulation of genomic imprinting

Machado, Filipe Brum
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/08/2012 PT
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66.75%
O imprinting genômico é um processo regulado epigeneticamente que faz com que os alelos sejam expressos de acordo com a sua origem parental. No cromossomo 11 (11p15.5), existem duas regiões controladoras de imprinting (ICR1 e ICR2), que controlam a expressão de genes marcados (imprinted). Os padrões de metilação dessas regiões podem ser alterados pela dissomia uniparental (DUP), que ocorre quando parte de ou um cromossomo inteiro do mesmo par de homólogos é herdado de somente um genitor. Erros mitóticos podem gerar mosaicismo com uma linhagem de células com DUP e a outra biparental. As síndromes de Silver-Russell (SSR) e Beckwith-Wiedemann (SBW) são doenças de alterações do imprinting genômico, envolvendo os cromossomos 7 (SSR) e 11 (SSR e SBW). A Hemihiperplasia Isolada (HHI) parece corresponder a uma forma mais leve da SBW.. No presente trabalho, foi realizada uma varredura in silico para busca de novos microssatélites nos cromossomos 7 e 11, e selecionados seis do tipo tetra ou pentanucleotídeos, no cromossomo 7, e 12, no cromossomo 11. O perfil de metilação nas ICRs foi verificado por três técnicas distintas: MS-MLPA, DESM-RT e por uma nova estratégia desenvolvida neste trabalho denominada DESM-QFPCR. Foram avaliados 32 pacientes com SBW...

Mosaicismo e evolução do perfil epigenético durante a gravidez; Mosaicism and evolution of epigenetic profile during pregnancy

Salomão, Karina Bezerra
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 06/03/2013 PT
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46.75%
O imprinting genômico, processo regulado epigeneticamente segundo o qual os genes se expressam de acordo com sua origem parental (paterna ou materna), está envolvido no desenvolvimento placentário. Na região cromossômica 11p15.5 encontram-se vários genes importantes para o desenvolvimento fetal e da placenta, os quais são regulados por duas principais regiões controladoras de imprinting (ICR1 e 2) onde se encontram as regiões diferencialmente metiladas H19DMR e KvDMR1, respectivamente. O imprinting genômico e a inativação aleatória do cromossomo X são processos epigenéticos presentes em mamíferos placentários. O presente trabalho teve como objetivo principal verificar a presença de mosaicismo do perfil epigenético entre tecidos extraembrionários de estágios precoces da gravidez (primeiro trimestre), e em vilosidade coriônica de placentas a termo (terceiro trimestre). Foram coletadas amostras de 10 gestações de primeiro trimestre (vilosidade coriônica, âmion, membrana de cordão umbilical e tecido embrionário) e 14 de terceiro trimestre (vilosidade coriônica), das quais 10 foram consideradas como controles e quatro utilizadas para estudo de mosaicismo restrito à vilosidade coriônica (coleta de amostras de todos os cotilédones). Após extração do DNA...

Expression and imprinting of insulin-like growth factor II (IGF2) and H19 genes in uterine leiomyomas

Rainho, C. A.; Pontes, A.; Rogatto, Silvia Regina
Fonte: Academic Press Inc. Publicador: Academic Press Inc.
Tipo: Artigo de Revista Científica Formato: 375-380
ENG
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56.58%
Genomic imprinting is defined as a gamete of origin-specific epigenetic modification of DNA leading to differential gene expression in the zygote. Several imprinted genes have been identified and some of them are associated with tumor development. We investigated the expression and the imprinting status of IGF2 and H19 genes in 47 uterine leiomyomas. Using allelic transcription assay, we detected the expression of the IGF2 gene in 10 of a total of 15 informative cases. No loss of imprinting, as determined by the finding of biallelic expression, was detected in any case. The expression of H19 gene was detected in 10 of 20 informative cases and the imprinting pattern was also maintained in all of them. Our data suggest that alterations in IGF2 and H19 genes expression by loss of imprinting do not occur in uterine leiomyomas. (C) 1999 Academic Press.

Placental hydroxymethylation vs methylation at the imprinting control region 2 on chromosome 11p15.5

Magalhaes,H.R.; Leite,S.B.P.; Paz,C.C.P. de; Duarte,G.; Ramos,E.S.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2013 EN
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56.59%
In addition to methylated cytosines (5-mCs), hydroxymethylcytosines (5-hmCs) are present in CpG dinucleotide-enriched regions and some transcription regulator binding sites. Unlike methylation, hydroxymethylation does not result in silencing of gene expression, and the most commonly used methods to study methylation, such as techniques based on restriction enzymatic digestion and/or bisulfite modification, are unable to distinguish between them. Genomic imprinting is a process of gene regulation where only one member of an allelic pair is expressed depending on the parental origin. Chromosome 11p15.5 has an imprinting control region (ICR2) that includes a differentially methylated region (KvDMR1) that guarantees parent-specific gene expression. The objective of the present study was to determine the presence of 5-hmC at the KvDMR1 in human placentas. We analyzed 16 third-trimester normal human placentas (chorionic villi). We compared two different methods based on real-time PCR after enzymatic digestion. The first method distinguished methylation from hydroxymethylation, while the other method did not. Unlike other methylation studies, subtle variations of methylation in ICRs could represent a drastic deregulation of the expression of imprinted genes...

GATM, the human ortholog of the mouse imprinted Gatm gene, escapes genomic imprinting in placenta

Miyamoto,Toshinobu; Sengoku,Kazuo; Hayashi,Hiroaki; Sasaki,Yoshihito; Jinno,Yoshihiro; Ishikawa,Mutsuo
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2005 EN
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66.54%
The GATM gene encodes L-arginine:glycine amidinotransferase, which catalyzes the conversion of L-arginine into guanidinoacetate, the rate-limiting step in the synthesis of creatine. Since, deficiencies in creatine synthesis and transport lead to certain forms of mental retardation in human, the human GATM gene appears to be involved in brain development. Recently it has been demonstrated that the mouse Gatm is expressed during development and is imprinted with maternal expression in the placenta and yolk sac, but not in embryonic tissues. We investigated the imprinting status of the human GATM by analyzing its expression in four human placentas. GATM was biallelically expressed, thus suggesting that this gene escapes genomic imprinting in placentas, differently from what has been reported in mouse extra-embryonic tissues.

Population Genetic Models of Genomic Imprinting

Pearce, G. P.; Spencer, H. G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1992 EN
Relevância na Pesquisa
46.76%
The phenomenon of genomic imprinting has recently excited much interest among experimental biologists. The population genetic consequences of imprinting, however, have remained largely unexplored. Several population genetic models are presented and the following conclusions drawn: (i) systems with genomic imprinting need not behave similarly to otherwise identical systems without imprinting; (ii) nevertheless, many of the models investigated can be shown to be formally equivalent to models without imprinting; (iii) consequently, imprinting often cannot be discovered by following allele frequency changes or examining equilibrium values; (iv) the formal equivalences fail to preserve some well known properties. For example, for populations incorporating genomic imprinting, parameter values exist that cause these populations to behave like populations without imprinting, but with heterozygote advantage, even though no such advantage is present in these imprinting populations. We call this last phenomenon ``pseudoheterosis.' The imprinting systems that fail to be formally equivalent to nonimprinting systems are those in which males and females are not equivalent, i.e., two-sex viability systems and sex-chromosome inactivation.

Genomic imprinting and environmental disease susceptibility.

Jirtle, R L; Sander, M; Barrett, J C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/2000 EN
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46.8%
Genomic imprinting is one of the most intriguing subtleties of modern genetics. The term "imprinting" refers to parent-of-origin-dependent gene expression. The presence of imprinted genes can cause cells with a full parental complement of functional autosomal genes to specifically express one allele but not the other, resulting in monoallelic expression of the imprinted loci. Genomic imprinting plays a critical role in fetal growth and behavioral development, and it is regulated by DNA methylation and chromatin structure. This paper summarizes the Genomic Imprinting and Environmental Disease Susceptibility Conference held 8-10 October 1998 at Duke University, Durham, North Carolina. The conference focused on the importance of genomic imprinting in determining susceptibility to environmentally induced diseases. Conference topics included rationales for imprinting: parental antagonism and speciation; methods for imprinted gene identification: allelic message display and monochromosomal mouse/human hybrids; properties of the imprinted gene cluster human 11p15.5 and mouse distal 7; the epigenetics of X-chromosome inactivation; variability in imprinting: imprint erasure, non-Mendelian inheritance ratios, and polymorphic imprinting; imprinting and behavior: genetics of bipolar disorder...

Maternal Effects as the Cause of Parent-of-Origin Effects That Mimic Genomic Imprinting

Hager, Reinmar; Cheverud, James M.; Wolf, Jason B.
Fonte: Genetics Society of America Publicador: Genetics Society of America
Tipo: Artigo de Revista Científica
Publicado em /03/2008 EN
Relevância na Pesquisa
46.78%
Epigenetic effects are increasingly recognized as an important source of variation in complex traits and have emerged as the focus of a rapidly expanding area of research. Principle among these effects is genomic imprinting, which has generally been examined in analyses of complex traits by testing for parent-of-origin-dependent effects of alleles. However, in most of these analyses maternal effects are confounded with genomic imprinting because they can produce the same patterns of phenotypic variation expected for various forms of imprinting. Distinguishing between the two is critical for genetic and evolutionary studies because they have entirely different patterns of gene expression and evolutionary dynamics. Using a simple single-locus model, we show that maternal genetic effects can result in patterns that mimic those expected under genomic imprinting. We further demonstrate how maternal effects and imprinting effects can be distinguished using genomic data from parents and offspring. The model results are applied to a genome scan for quantitative trait loci (QTL) affecting growth- and weight-related traits in mice to illustrate how maternal effects can mimic imprinting. This genome scan revealed five separate maternal-effect loci that caused a diversity of patterns mimicking those expected under various modes of genomic imprinting. These results demonstrate that the appearance of parent-of-origin-dependent effects (POEs) of alleles at a locus cannot be taken as direct evidence that the locus is imprinted. Moreover...

Genomic Imprinting Mechanisms in Mammals

Ideraabdullah, Folami Y.; Vigneau, Sebastien; Bartolomei, Marisa S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.77%
Genomic imprinting is a form of epigenetic gene regulation that results in expression from a single allele in a parent-of-origin-dependent manner. This form of monoallelic expression affects a small but growing number of genes and is essential to normal mammalian development. Despite extensive studies and some major breakthroughs regarding this intriguing phenomenon, we have not yet fully characterized the underlying molecular mechanisms of genomic imprinting. This is in part due to the complexity of the system in that the epigenetic markings required for proper imprinting must be established in the germline, maintained throughout development, and then erased before being re-established in the next generation’s germline. Furthermore, imprinted gene expression is often tissue or stage-specific. It has also become clear that while imprinted loci across the genome seem to rely consistently on epigenetic markings of DNA methylation and/or histone modifications to discern parental alleles, the regulatory activities underlying these markings vary among loci. Here, we discuss different modes of imprinting regulation in mammals and how perturbations of these systems result in human disease. We focus mostly on the mechanism of genomic imprinting mediated by insulators as is present at the H19/Igf2 locus...

The origin and evolution of genomic imprinting and viviparity in mammals

Renfree, Marilyn B.; Suzuki, Shunsuke; Kaneko-Ishino, Tomoko
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Publicado em 05/01/2013 EN
Relevância na Pesquisa
46.82%
Genomic imprinting is widespread in eutherian mammals. Marsupial mammals also have genomic imprinting, but in fewer loci. It has long been thought that genomic imprinting is somehow related to placentation and/or viviparity in mammals, although neither is restricted to mammals. Most imprinted genes are expressed in the placenta. There is no evidence for genomic imprinting in the egg-laying monotreme mammals, despite their short-lived placenta that transfers nutrients from mother to embryo. Post natal genomic imprinting also occurs, especially in the brain. However, little attention has been paid to the primary source of nutrition in the neonate in all mammals, the mammary gland. Differentially methylated regions (DMRs) play an important role as imprinting control centres in each imprinted region which usually comprises both paternally and maternally expressed genes (PEGs and MEGs). The DMR is established in the male or female germline (the gDMR). Comprehensive comparative genome studies demonstrated that two imprinted regions, PEG10 and IGF2-H19, are conserved in both marsupials and eutherians and that PEG10 and H19 DMRs emerged in the therian ancestor at least 160 Ma, indicating the ancestral origin of genomic imprinting during therian mammal evolution. Importantly...

Evolution of genomic imprinting as a coordinator of coadapted gene expression

Wolf, Jason B.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.76%
Genomic imprinting is an epigenetic phenomenon in which the expression of a gene copy inherited from the mother differs from that of the copy inherited from the father. Many imprinted genes appear to be highly interconnected through interactions mediated by proteins, RNA, and DNA. These kinds of interactions often favor the evolution of genetic coadaptation, where beneficially interacting alleles evolve to become coinherited. Here I demonstrate theoretically that the presence of gene interactions that favor coadaptation can also favor the evolution of genomic imprinting. Selection favors genomic imprinting because it coordinates the coexpression of positively interacting alleles at different loci. Evolution is expected to proceed through a scenario where selection builds associations between beneficial combinations of alleles and, if one locus evolves to become imprinted, it leads to selection for its interacting partners to match its pattern of imprinting. This process should favor the evolution of physical linkage between interacting genes and therefore may help explain why imprinted genes tend to be found in clusters. The model suggests that, whereas some genes are expected to evolve their imprinting status because selection directly favors a specific pattern of parent-of-origin-dependent expression...

An Investigation of genomic imprinting on the X-chromosome

Mak, Lillian
Fonte: Quens University Publicador: Quens University
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
66.82%
An assumption of Mendelian genetics is that identical alleles which are paternally and maternally inherited are equally expressed in offspring (Ruvinsky 1999). The genomic imprinting phenomenon does not follow the classical views of Mendel, suggesting that although alleles may be genetically equivalent, they may not be functionally equivalent depending on which parent they are inherited from (Mcgrath and Solter 1984). Genomic imprinting is typically expressed as the relative silencing of a paternally or maternally inherited allele. Imprinting has potential costs as the resulting hemizygosity leaves an individual vulnerable to genetic abnormalities, as deleterious traits are not masked by a dominant allele counterpart (Bartolomei et al. 1997). Most theories proposed to explain the evolutionary function of genomic imprinting are related to maternal provisioning and limited to taxa that can provision their offspring after fertilization (Moore and Haig 1991). Day and Bonduriansky (2004) have developed a unified model of imprinting that can be applied to all taxa where the phenomenon has been observed. The Intralocus Sexual Conflict (ISC) theory of genomic imprinting proposed by Day and Bonduriansky (2004) suggests that the imprinting mechanism has evolved to alleviate intralocus sexual conflict. With the ISC model...

The Evolution of Genomic Imprinting and X Chromosome Inactivation in Mammals

Hore, Tim
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
EN
Relevância na Pesquisa
66.69%
Genomic imprinting is responsible for monoallelic gene expression that depends on the sex of the parent from which the alleles (one active, one silent) were inherited. X-chromosome inactivation is also a form of monoallelic gene expression. One of the two X chromosomes is transcriptionally silenced in the somatic cells of females, effectively equalising gene dosage with males who have only one X chromosome that is not complemented by a gene poor Y chromosome. X chromosome inactivation is random in eutherian mammals, but imprinted in marsupials, and in the extraembryonic membranes of some placentals. Imprinting and X inactivation have been studied in great detail in placental mammals (particularly humans and mice), and appear to occur also in marsupial mammals. However, both phenomena appear to have evolved specifically in mammals, since there is no evidence of imprinting or X inactivation in non-mammalian vertebrates, which do not show parent of origin effects and possess different sex chromosomes and dosage compensation mechanisms to mammals.¶ In order to understand how imprinting and X inactivation evolved, I have focused on the mammals most distantly related to human and mouse. I compared the sequence, location and expression of genes from major imprinted domains...

Epigenetics and imprinting of the trophoblast - A workshop report

Ferguson-Smith, A.; Moore, T.; Detmar, J.; Lewis, A.; Hemberger, J.; Jammes, H.; Kelsey, G.; Roberts, C.; Constancia, M.
Fonte: W B Saunders Co Ltd Publicador: W B Saunders Co Ltd
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
56.52%
Genomic imprinting is a remarkable process that causes genes to be expressed or repressed depending on their parental-origin. Imprinted genes play important roles in prenatal growth and organ development. Postnatally, imprinted genes can contribute to the regulation of metabolic pathways and behaviour associated with the control of resources. One of the most important sites of imprinted gene action is the placenta. During this workshop at the 11th meeting of the International Federation of Placenta Associations/European Placenta Group held in Glasgow, a series of short talks were presented providing an overview of the evolution, function and mechanisms of imprinting in mammals with particular reference to the placenta. In addition, epigenetic control of trophoblast development and function were considered. This report summarises the contributions to the workshop.; http://www.elsevier.com/wps/find/journaldescription.cws_home/623064/description#description; A.C. Ferguson-Smitha, T. Mooreb, J. Detmarc, A. Lewisd, M. Hembergerd, H. Jammese, G. Kelseyd, C.T. Robertsf, H. Jonesg and M. Constanciad

Genomic imprinting and carcinogenesis

Yun, K.
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
66.63%
The Mendelian inheritance is based on the fundamental rule in which mammalian genes are expressed equally from two homologous biparental alleles. Recently a small number of genes have been identified to show an exception to this rule in that homologous alleles can function differently in somatic cells depending on whether they come from the mother or the father. This intriguing biological phenomenon is called as genomic imprinting which does not conform classical Mendelian inheritance and has potentially far reaching implications for genetics, evolution, developmental biology and pathology including cancer. The gene encoding insulin-like growth factor 2 (IGF2) harbors at llp15.5 and serves as paradigm for an imprinted gene. The lGF2 gene has been demonstrated to be imprinted with the paternal allele expressed and the maternal being silent which is evolutionally conserved between mice and human. Loss of imprinting (L01) of IGF2 has been demonstrated in a dozen of tumor types including Wilms tumor (WT) with a promise of many more to come. The LOT of IGF2 may induce increased or dcrcgulated IGF2 expression which could initiate the onset of WT. Thus the L01 of IGF2 may provide a novel mechanism of gene activation and play a role in the development of a wide range of tumors. This review also discusses other imprinted genes on llp15 which may have a role in WT or other diseases. Finally molecular mechanisms of genomic imprinting are discussed.

Genomic imprinting and Beckwith-Wiedemann syndrome

Hatada, I.; Mukai, T.
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
66.47%
Genomic imprinting is the parental-allelespecific expression of genes. Beckwith-Wiedemann syndrome (BWS), a congenital overgrowth syndrome with increased risk of childhood tumors, is one of the well-known diseases caused by imprinted genes. The imprinted genes causing BWS are discussed in this review.