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Salima El Chehadeh, Renaud Touraine, Fabienne Prieur, Willie Reardon, Thierry Bienvenu, Sandrine Chantot-Bastaraud, Martine Doco-Fenzy, Emilie Landais, Christophe Philippe, Nathalie Marle, Patrick Callier, Anne-Laure Mosca-Boidron, Francine Mugneret, Nathalie Le Meur, Alice Goldenberg, Anne-Marie Guerrot, Pascal Chambon, Véronique Satre, Charles Coutton, Pierre-Simon Jouk, Françoise Devillard, Klaus Dieterich, Alexandra Afenjar, Lydie Burglen, Marie-Laure Moutard, Marie-Claude Addor, Sébastien Lebon, Danielle Martinet, Jean-Luc Alessandri, Bérénice Doray, Marguerite Miguet, Didier Devys, Pascale Saugier-Veber, Séverine Drunat, Bernard Aral, Valérie Kremer, Stéphane Rondeau, Anne-Claude Tabet, Julien Thevenon, Christel Thauvin-Robinet, Nathalie Perreton, Vincent Des Portes, Laurence Faivre
Duplication of the Xq28 region, involving MECP2 (dupMECP2), has been primarily described in males with severe developmental delay, spasticity, epilepsy, stereotyped movements and recurrent infections. Carrier mothers are usually asymptomatic with an extremely skewed X chromosome inactivation (XCI) pattern. We report a series of six novel symptomatic females carrying a de novo interstitial dupMECP2, and review the 14 symptomatic females reported to date, with the aim to further delineate their phenotype and give clues for genetic counselling...
October 19, 2016: Clinical Genetics
Geber Pena, Christina Michalski, Yong Qin, Robert Donnelly, Ziad Sifri, Anne Mosenthal, David Livingston, Zoltan Spolarics
Sex-related outcome disparities following severe trauma have been demonstrated in human and animal studies however sex hormone status could not fully account for the differences. This study tested whether X-linked cellular mosaicism, which is unique to females, could represent a genetically based mechanism contributing to sex-related immuno-modulation following trauma. Serial blood samples collected for routine laboratory tests were analyzed for ChrX inactivation (XCI) ratios in white blood cells. 39 severely injured (mean ISS 19) female trauma patients on mixed racial and ethnic background were tested for initial (baseline) and trauma-induced changes in XCI-ratios and their associations with severity of injury and clinical outcome...
September 29, 2016: Shock
Federica Federici, Aristea Magaraki, Evelyne Wassenaar, Catherina J H van Veen-Buurman, Christine van de Werken, Esther B Baart, Joop S E Laven, J Anton Grootegoed, Joost Gribnau, Willy M Baarends
In mouse female preimplantation embryos, the paternal X chromosome (Xp) is silenced by imprinted X chromosome inactivation (iXCI). This requires production of the noncoding Xist RNA in cis, from the Xp. The Xist locus on the maternally inherited X chromosome (Xm) is refractory to activation due to the presence of an imprint. Paternal inheritance of an Xist deletion (XpΔXist) is embryonic lethal to female embryos, due to iXCI abolishment. Here, we circumvented the histone-to-protamine and protamine-to-histone transitions of the paternal genome, by fertilization of oocytes via injection of round spermatids (ROSI)...
October 2016: PLoS Genetics
Lin Yang, James E Kirby, Hongjae Sunwoo, Jeannie T Lee
X-chromosome inactivation (XCI) compensates for differences in X-chromosome number between male and female mammals. XCI is orchestrated by Xist RNA, whose expression in early development leads to transcriptional silencing of one X chromosome in the female. Knockout studies have established a requirement for Xist with inviability of female embryos that inherit an Xist deletion from the father. Here, we report that female mice lacking Xist RNA can, surprisingly, develop and survive to term. Xist-null females are born at lower frequency and are smaller at birth, but organogenesis is mostly normal...
August 1, 2016: Genes & Development
Friedemann Loos, Cheryl Maduro, Agnese Loda, Johannes Lehmann, Gert-Jan Kremers, Derk Ten Berge, J Anton Grootegoed, Joost Gribnau
In female mammals, X chromosome inactivation (XCI) is a key process in the control of gene dosage compensation between X-linked genes and autosomes. Xist and Tsix, two overlapping antisense-transcribed noncoding genes, are central elements of the X inactivation center (Xic) regulating XCI. Xist upregulation results in the coating of the entire X chromosome by Xist RNA in cis, whereas Tsix transcription acts as a negative regulator of Xist Here, we generated Xist and Tsix reporter mouse embryonic stem (ES) cell lines to study the genetic and dynamic regulation of these genes upon differentiation...
November 1, 2016: Molecular and Cellular Biology
Chunhe Li, Tian Hong, Chiu-Ho Webb, Heather Karner, Sha Sun, Qing Nie
X-chromosome inactivation (XCI) is the mammalian dosage compensation strategy for balancing sex chromosome content between females and males. While works exist on initiation of symmetric breaking, the underlying allelic choice mechanisms and dynamic regulation responsible for the asymmetric fate determination of XCI remain elusive. Here we combine mathematical modeling and experimental data to examine the mechanism of XCI fate decision by analyzing the signaling regulatory circuit associated with long noncoding RNAs (lncRNAs) involved in XCI...
2016: Scientific Reports
Martina Rinčić, Ivan Y Iourov, Thomas Liehr
BACKGROUND: Chromosome counting is a process in which cells determine somehow their intrinsic chromosome number(s). The best-studied cellular mechanism that involves chromosome counting is 'chromosome-kissing' and X-chromosome inactivation (XCI) mechanism. It is necessary for the well-known dosage compensation between the genders in mammals to balance the number of active X-chromosomes (Xa) with regard to diploid set of autosomes. At the onset of XCI, two X-chromosomes are coming in close proximity and pair physically by a specific segment denominated X-pairing region (Xpr) that involves the SLC16A2 gene...
2016: Molecular Cytogenetics
Niamh Forde, Veronica Maillo, Peadar Ó Gaora, Constantine A Simintiras, Roger G Sturmey, Alan D Ealy, Thomas E Spencer, Alfonso Gutierrez-Adan, Dimitrios Rizos, Pat Lonergan
In cattle, maternal recognition of pregnancy occurs on Day 16 via secretion of interferon tau (IFNT) by the conceptus. The endometrium can distinguish between embryos with different developmental competencies. In eutherian mammals, X-chromosome inactivation (XCI) is required to ensure an equal transcriptional level of most X-linked genes for both male and female embryos in adult tissues, but this process is markedly different in cattle than mice. We examined how sexual dimorphism affected conceptus transcript abundance and amino acid composition as well as the endometrial transcriptome during the peri-implantation period of pregnancy...
August 3, 2016: Biology of Reproduction
Geng Chen, John Paul Schell, Julio Aguila Benitez, Sophie Petropoulos, Marlene Yilmaz, Björn Reinius, Zhanna Alekseenko, Leming Shi, Eva Hedlund, Fredrik Lanner, Rickard Sandberg, Qiaolin Deng
Pluripotency, differentiation, and X Chromosome inactivation (XCI) are key aspects of embryonic development. However, the underlying relationship and mechanisms among these processes remain unclear. Here, we systematically dissected these features along developmental progression using mouse embryonic stem cells (mESCs) and single-cell RNA sequencing with allelic resolution. We found that mESCs grown in a ground state 2i condition displayed transcriptomic profiles diffused from preimplantation mouse embryonic cells, whereas EpiStem cells closely resembled the post-implantation epiblast...
October 2016: Genome Research
Manuel Buscarlet, Alain Tessier, Sylvie Provost, Luigina Mollica, Lambert Busque
Epigenetic alteration may play a role in age-associated dysfunction of stem cells, and predispose to the development of hematological cancers. We analysed global levels of hematopoietic 5-hydroxymethylcytosine (5hmC) and 5-methylcytosine (5mC) in a cross sectional study comprising 198 unrelated individuals from four age categories (neonates, 25-30, 70-75, and >90 years old) by mass spectrometry (LC-ESI-MS/MS-MRM). X-chromosome inactivation (XCI) ratios and telomere length (TL) were measured in all individuals by PCR...
July 27, 2016: Experimental Hematology
Luca Giorgetti, Bryan R Lajoie, Ava C Carter, Mikael Attia, Ye Zhan, Jin Xu, Chong Jian Chen, Noam Kaplan, Howard Y Chang, Edith Heard, Job Dekker
X-chromosome inactivation (XCI) involves major reorganization of the X chromosome as it becomes silent and heterochromatic. During female mammalian development, XCI is triggered by upregulation of the non-coding Xist RNA from one of the two X chromosomes. Xist coats the chromosome in cis and induces silencing of almost all genes via its A-repeat region, although some genes (constitutive escapees) avoid silencing in most cell types, and others (facultative escapees) escape XCI only in specific contexts. A role for Xist in organizing the inactive X (Xi) chromosome has been proposed...
July 28, 2016: Nature
Céline Vallot, Jean-François Ouimette, Claire Rougeulle
X chromosome inactivation (XCI) is an essential epigenetic process that ensures X-linked gene dosage equilibrium between sexes in mammals. XCI is dynamically regulated during development in a manner that is intimately linked to differentiation. Numerous studies, which we review here, have explored the dynamics of X inactivation and reactivation in the context of development, differentiation and diseases, and the phenotypic and molecular link between the inactive status, and the cellular context. Here, we also assess whether XCI is a uniform mechanism in mammals by analyzing epigenetic signatures of the inactive X (Xi) in different species and cellular contexts...
September 2016: BioEssays: News and Reviews in Molecular, Cellular and Developmental Biology
Sami B Kanaan, Onur E Onat, Nathalie Balandraud, Gabriel V Martin, J Lee Nelson, Doua F Azzouz, Isabelle Auger, Fanny Arnoux, Marielle Martin, Jean Roudier, Tayfun Ozcelik, Nathalie C Lambert
BACKGROUND: Autoimmune diseases, including rheumatoid arthritis (RA) and systemic sclerosis (SSc) are characterized by a strong genetic susceptibility from the Human Leucocyte Antigen (HLA) locus. Additionally, disorders of epigenetic processes, in particular non-random X chromosome inactivation (XCI), have been reported in many female-predominant autoimmune diseases. Here we test the hypothesis that women with RA or SSc who are strongly genetically predisposed are less susceptible to XCI bias...
2016: PloS One
Mary G Dandulakis, Kesavan Meganathan, Kristen L Kroll, Azad Bonni, John N Constantino
Induced pluripotent stem cells (iPSCs) allow researchers to make customized patient-derived cell lines by reprogramming noninvasively retrieved somatic cells. These cell lines have the potential to faithfully represent an individual's genetic background; therefore, in the absence of available human brain tissue from a living patient, these models have a significant advantage relative to other models of neurodevelopmental disease. When using human induced pluripotent stem cells (hiPSCs) to model X-linked developmental disorders or inherited conditions that undergo sex-specific modulation of penetrance (e...
2016: Journal of Neurodevelopmental Disorders
Antonius Christianto, Syouichi Katayama, Isamu Kameshita, Tetsuya Inazu
Rett syndrome (RTT) is a severe X-linked dominant inheritance disorder with a wide spectrum of clinical manifestations. Mutations in Methyl CpG binding protein 2 (MECP2), Cyclin dependent kinase-like 5 (CDKL5) and Forkhead box G1 (FOXG1) have been associated with classic and/or variant RTT. This study was conducted to identify the responsible gene(s) in atypical RTT patient, and to examine the effect of the mutation on protein function. DNA sequence analysis showed a novel heterozygous mutation in CDKL5 identified as c...
August 1, 2016: Clinica Chimica Acta; International Journal of Clinical Chemistry
Pingyuan Xie, Qi Ouyang, Lizhi Leng, Liang Hu, Dehua Cheng, Yueqiu Tan, Guangxiu Lu, Ge Lin
X chromosome inactivation (XCI) is required for dosage compensation of X-linked genes in human female cells. Several previous reports have described the promiscuous XCI status in long-term cultured female human embryonic stem cells (hESCs), and the majority of them exhibit non-random XCI. However, when and how such female hESCs acquire the aberrant XCI states during culture is unknown. Herein, through comparing the XCI states in 18 paired hES cell lines throughout early culture, we revealed a uniform dynamic change during this culture period under a widely used culture condition...
July 2016: Stem Cell Research
Chia-Yu Chen, Chieh-Hsiang Chan, Chun-Ming Chen, Yin-Shuan Tsai, Tsung-Yuan Tsai, Yan-Hwa Wu Lee, Li-Ru You
The X-linked DEAD-box RNA helicase DDX3 (DDX3X) is a multifunctional protein that has been implicated in gene regulation, cell cycle control, apoptosis, and tumorigenesis. However, the precise physiological function of Ddx3x during development remains unknown. Here, we show that loss of Ddx3x results in an early post-implantation lethality in male mice. The size of the epiblast marked by Oct3/4 is dramatically reduced in embryonic day 6.5 (E6.5) Ddx3x(-)/Y embryos. Preferential paternal X chromosome inactivation (XCI) in extraembryonic tissues of Ddx3x heterozygous (Ddx3x(-/+)) female mice with a maternally inherited null allele leads to placental abnormalities and embryonic lethality during development...
May 14, 2016: Human Molecular Genetics
Miguel Casanova, Tharvesh Moideen Liyakat Ali, Claire Rougeulle
X-chromosome inactivation (XCI) in mammals represents an exceptional example of transcriptional co-regulation occurring at the level of an entire chromosome. XCI is considered as a means to compensate for gene dosage imbalance between sexes, yet the largest part of the chromosome is composed of repeated elements of different nature and origins. Here we consider XCI from a repeat point of view, interrogating the mechanisms for inactivating X chromosome-derived repeated sequences and discussing the contribution of repetitive elements to the silencing process itself and to its evolution...
August 2016: Seminars in Cell & Developmental Biology
Giulia Furlan, Claire Rougeulle
X-chromosome inactivation (XCI) is a chromosome-wide regulatory process that ensures dosage compensation for X-linked genes in Theria. XCI is established during early embryogenesis and is developmentally regulated. Different XCI strategies exist in mammalian infraclasses and the regulation of this process varies also among closely related species. In Eutheria, initiation of XCI is orchestrated by a cis-acting locus, the X-inactivation center (Xic), which is particularly enriched in genes producing long noncoding RNAs (lncRNAs)...
September 2016: Wiley Interdisciplinary Reviews. RNA
Hegias Mira-Bontenbal, Joost Gribnau
To achieve dosage compensation of X-linked gene expression, female mammalian cells inactivate one X chromosome through a process called X-chromosome inactivation (XCI). A central component of this process is the X-encoded long non-coding RNA Xist. Following upregulation from one X chromosome, Xist spreads in cis, kicking off a plethora of events that ultimately results in stable X-linked gene repression, which is then faithfully transmitted to all daughter cells. In the last decades, intensive work has been undertaken to understand each of the steps in XCI, namely Xist transcription control, Xist spreading and localization, and silencing of gene expression...
April 25, 2016: Current Biology: CB
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