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https://www.readbyqxmd.com/read/28408975/x-chromosome-inactivation-new-players-in-the-initiation-of-gene-silencing
#1
REVIEW
Ines Pinheiro, Edith Heard
X chromosome inactivation (XCI) is a dosage compensation process that was adopted by female mammals to balance gene dosage between XX females and XY males. XCI starts with the upregulation of the non-coding RNA Xist, after which most X-linked genes are silenced and acquire a repressive chromatin state. Even though the chromatin marks of the inactive X have been fairly well described, the mechanisms responsible for the initiation of XCI remain largely unknown. In this review, we discuss recent developments that revealed unexpected factors playing a role in XCI and that might be of crucial importance to understand the mechanisms responsible for the very first steps of this chromosome-wide gene-silencing event...
2017: F1000Research
https://www.readbyqxmd.com/read/28401797/the-state-of-skewed-x-chromosome-inactivation-is-retained-in-the-induced-pluripotent-stem-cells-from-a-female-with-hemophilia-b
#2
Cuicui Lyu, Jun Shen, Jianping Zhang, Feng Xue, Xiaofan Liu, Wei Liu, Rongfeng Fu, Liyan Zhang, Huiyuan Li, Donglei Zhang, Xiaobing Zhang, Tao Cheng, Renchi Yang, Lei Zhang
Skewed X chromosome inactivation (XCI) is a rare reason for hemophilia B in females. It is indefinite whether X chromosome reactivation (XCR) would occur when cells of hemophilia B patients with skewed XCI were reprogrammed into induced pluripotent stem cells (iPSCs). In this study, we investigated a female hemophilia B patient with a known F9 gene mutation: c.676C>T, p.Arg226Trp. We demonstrated that skewed XCI was the pathogenesis of the patient, and we successfully generated numerous iPSCs colonies of the patient from PBMNCs, which was the first time for generating hemophilia-specific iPSCs from PBMNCs...
April 12, 2017: Stem Cells and Development
https://www.readbyqxmd.com/read/28394482/familial-cases-and-male-cases-with-mecp2-mutations
#3
Qingping Zhang, Ying Zhao, Xinhua Bao, Jinjun Luo, Xiaoying Zhang, Jiarui Li, Liping Wei, Xiru Wu
This is the first report of Chinese familial cases with Rett syndrome (RTT) or X-linked mental retardation (XLMR). RTT is a neurodevelopmental disorder that almost exclusively affects females. Most RTT cases are sporadic. We have studied eight cases with MECP2 mutations in six Chinese families, including three females and five males with RTT or XLMR. All shared identical MECP2 mutations with their mothers. The three females fulfilled the diagnostic criteria for RTT, while the five males were XLMR. A random X-chromosome inactive (XCI) pattern was seen in all the three female patients and two mothers while a skewed XCI in the rest four mothers...
April 10, 2017: American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics
https://www.readbyqxmd.com/read/28387970/mutation-of-the-xist-gene-up-regulates-expression-of-x-linked-genes-but-decreases-the-developmental-rates-of-cloned-male-porcine-embryos
#4
Yang Yang, Dan Wu, Dewu Liu, Junsong Shi, Rong Zhou, Xiaoyan He, Jianping Quan, Gengyuan Cai, Enqin Zheng, Zhenfang Wu, Zicong Li
XIST is an X-linked, non-coding gene responsible for the cis induction of X-chromosome inactivation (XCI). Knockout of the XIST allele on an active X chromosome abolishes erroneous XCI and enhances the in vivo development of cloned mouse embryos by more than tenfold. This study aimed to investigate if a similar manipulation would improve cloning efficiency in pigs. A male, porcine kidney cell line containing an EGFP insert in exon 1 of the XIST gene, resulting in a knockout allele (XIST-KO), was generated by homologous recombination using transcription activator-like effector nucleases (TALENs)...
April 7, 2017: Molecular Reproduction and Development
https://www.readbyqxmd.com/read/28371302/functional-monosomy-of-6q27-qter-and-functional-disomy-of-xpter-p22-11-due-to-x-6-translocation-with-an-atypical-x-inactivation-pattern
#5
Anna Podolska, Albrecht Kobelt, Sigrid Fuchs, Karl Hackmann, Andreas Rump, Evelin Schröck, Kerstin Kutsche, Nataliya Di Donato
Pattern of X chromosome inactivation (XCI) is typically random in females. However, chromosomal rearrangements affecting the X chromosome can result in XCI skewing due to cell growth disadvantage. In case of an X;autosome translocation, this usually leads to an XCI pattern of 100:0 with the derivative X being the active one in the majority of females. A de novo balanced X;6 translocation [46,X,t(X;6)(p22.1;q27)] and a completely skewed XCI pattern (100:0) were detected in a female patient with microcephaly, cerebellar vermis hypoplasia, heart defect, and severe developmental delay...
March 31, 2017: American Journal of Medical Genetics. Part A
https://www.readbyqxmd.com/read/28368037/high-resolution-rna-allelotyping-along-the-inactive-x-chromosome-evidence-of-rna-polymerase-iii-in-regulating-chromatin-configuration
#6
Ru Hong, Bingqing Lin, Xinyi Lu, Lan-Tian Lai, Xin Chen, Amartya Sanyal, Huck-Hui Ng, Kun Zhang, Li-Feng Zhang
We carried out padlock capture, a high-resolution RNA allelotyping method, to study X chromosome inactivation (XCI). We examined the gene reactivation pattern along the inactive X (Xi), after Xist (X-inactive specific transcript), a prototype long non-coding RNA essential for establishing X chromosome inactivation (XCI) in early embryos, is conditionally deleted from Xi in somatic cells (Xi(∆Xist)). We also monitored the behaviors of X-linked non-coding transcripts before and after XCI. In each mutant cell line, gene reactivation occurs to ~6% genes along Xi(∆Xist) in a recognizable pattern...
April 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28320934/allele-specific-non-cg-dna-methylation-marks-domains-of-active-chromatin-in-female-mouse-brain
#7
Christopher L Keown, Joel B Berletch, Rosa Castanon, Joseph R Nery, Christine M Disteche, Joseph R Ecker, Eran A Mukamel
DNA methylation at gene promoters in a CG context is associated with transcriptional repression, including at genes silenced on the inactive X chromosome in females. Non-CG methylation (mCH) is a distinct feature of the neuronal epigenome that is differentially distributed between males and females on the X chromosome. However, little is known about differences in mCH on the active (Xa) and inactive (Xi) X chromosomes because stochastic X-chromosome inactivation (XCI) confounds allele-specific epigenomic profiling...
April 4, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28316128/skewed-x-chromosome-inactivation-plays-a-crucial-role-in-the-onset-of-symptoms-in-carriers-of-becker-muscular-dystrophy
#8
Emanuela Viggiano, Esther Picillo, Manuela Ergoli, Alessandra Cirillo, Stefania Del Gaudio, Luisa Politano
BACKGROUND: Becker muscular dystrophy (BMD) is an X-linked recessive disorder affecting about 1:18,000 male births. Female carriers are usually asymptomatic, but 2.5-18% may present muscle or heart symptoms. In the present work the role of the X chromosome inactivation (XCI) on the onset of symptoms in BMD carriers was analysed and compared with the pattern observed in Duchenne muscular dystrophy (DMD) carriers. METHODS: XCI was determined on the lymphocytes of 36 BMD carriers - both symptomatic and not symptomatic - from 11 families requiring genetic advice at the Cardiomyology and Medical Genetics of the Second University of Naples, through the AR methylation-based assay...
March 18, 2017: Journal of Gene Medicine
https://www.readbyqxmd.com/read/28315662/insights-into-the-establishment-of-chromatin-states-in-pluripotent-cells-from-studies-of-x-inactivation
#9
REVIEW
Andreas Postlmayr, Anton Wutz
Animal development entails the sequential and coordinated specialisation of cells. During cell differentiation transcription factors, cell signalling pathways and chromatin associated protein complexes cooperate in regulating the expression of a large number of genes. Here we review the present understanding of the establishment of chromatin states by focusing on X chromosome inactivation (XCI) as a model for facultative heterochromatin formation in female embryonic cells. The inactive X chromosome (Xi) is large enough to be investigated by biochenical and microscopy techniques...
March 15, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28257137/novel-players-in-x-inactivation-insights-into-xist-mediated-gene-silencing-and-chromosome-conformation
#10
REVIEW
Simão T da Rocha, Edith Heard
The nuclear long noncoding RNA (lncRNA) Xist ensures X-chromosome inactivation (XCI) in female placental mammals. Although Xist is one of the most intensively studied lncRNAs, the mechanisms associated with its capacity to trigger chromosome-wide gene silencing, the formation of facultative heterochromatin and an unusual 3D conformation of the inactive X chromosome (Xi) have remained elusive. Now researchers have identified novel functional partners of Xist in a series of breakthrough studies, using unbiased techniques to isolate Xist-bound proteins, as well as forward genetic screens...
March 3, 2017: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/28236732/x-chromosome-inactivation-silencing-topology-and-reactivation
#11
REVIEW
Teresa Robert Finestra, Joost Gribnau
To ensure X-linked gene dosage compensation between females (XX) and males (XY), one X chromosome undergoes X chromosome inactivation (XCI) in female cells. This process is tightly regulated throughout development by many different factors, with Xist as a key regulator, encoding a long non-coding RNA, involved in establishment of several layers of repressive epigenetic modifications. Several recent studies on XCI focusing on identification and characterization of Xist RNA-protein interactors, revealed new factors involved in gene silencing, genome topology and nuclear membrane attachment, amongst others...
February 21, 2017: Current Opinion in Cell Biology
https://www.readbyqxmd.com/read/28220611/non-coding-rnas-emerging-regulatory-factors-in-the-derivation-and-differentiation-of-mammalian-parthenogenetic-embryonic-stem-cells
#12
REVIEW
Jihong Cui, Xin Xie
Parthenogenetic embryonic stem cells (PESCs) are ESCs derived from early parthenogenetic embryos. Haploid PESCs, containing haploid DNA, originate from a single sperm or occyte, while, diploid PESCs originate from two fused occytes. Most PESC lines used so far are diploid. PESCs exhibit representative pluripotent stem cell features, such as the capacity for self-renewal and the pariticular molecular signatures. Whereas, PESCs display distinctive properties, such as differential regulation of X-chromosome inactivation (XCI) and divergent monitor of genes involved in multiple biological processes...
May 2017: Cell Biology International
https://www.readbyqxmd.com/read/27896428/xci-escaping-gene-kdm5c-contributes-to-ovarian-development-via-downregulating-mir-320a
#13
Yi-Xi Sun, Yi-Xin Zhang, Dan Zhang, Chen-Ming Xu, Song-Chang Chen, Jun-Yu Zhang, Ye-Chun Ruan, Feng Chen, Run-Ju Zhang, Ye-Qing Qian, Yi-Feng Liu, Lu-Yang Jin, Tian-Tian Yu, Hai-Yan Xu, Yu-Qin Luo, Xin-Mei Liu, Fei Sun, Jian-Zhong Sheng, He-Feng Huang
Mechanisms underlying female gonadal dysgenesis remain unclarified and relatively unstudied. Whether X-chromosome inactivation (XCI)-escaping genes and microRNAs (miRNAs) contribute to this condition is currently unknown. We compared 45,X Turner Syndrome women with 46,XX normal women, and investigated differentially expressed miRNAs in Turner Syndrome through plasma miRNA sequencing. We found that miR-320a was consistently upregulated not only in 45,X plasma and peripheral blood mononuclear cells (PBMCs), but also in 45,X fetal gonadal tissues...
November 28, 2016: Human Genetics
https://www.readbyqxmd.com/read/27792840/maternal-genetic-polymorphisms-and-unexplained-recurrent-miscarriage-a-systematic-review-and-meta-analysis
#14
REVIEW
X Shi, X Xie, Y Jia, S Li
The roles of genetic polymorphisms in the pathogenesis of recurrent miscarriage (RM) have been intensively studied. However, the results of these studies were inconsistent, especially when conducted in different populations. Therefore, we performed the current study to systematically review the broad spectrum of genetic polymorphisms that were suspected to be involved in RM, and discussed potential genetic biomarkers of RM. Eligible articles were identified in PubMed, Medline, Embase and CNKI. Odd ratios (ORs) and 95% confidence intervals (CIs) were used to describe the strength of association, and a probability value (p value) of 0...
February 2017: Clinical Genetics
https://www.readbyqxmd.com/read/27777941/a-review-of-rett-syndrome-rtt-with-induced-pluripotent-stem-cells
#15
REVIEW
Vellingiri Balachandar, Venkatesan Dhivya, Mohan Gomathi, Subramaniam Mohanadevi, Balasubramanian Venkatesh, Bharathi Geetha
Human induced pluripotent stem cells (hiPSCs) are pluripotent stem cells generated from somatic cells by the introduction of a combination of pluripotency-associated genes such as OCT4, SOX2, along with either KLF4 and c-MYC or NANOG and LIN28 via retroviral or lentiviral vectors. Most importantly, hiPSCs are similar to human embryonic stem cells (hESCs) functionally as they are pluripotent and can potentially differentiate into any desired cell type when provided with the appropriate cues, but do not have the ethical issues surrounding hESCs...
2016: Stem Cell Investigation
https://www.readbyqxmd.com/read/27761913/xq28-duplication-including-mecp2-in-six-unreported-affected-females-what-can-we-learn-for-diagnosis-and-genetic-counselling
#16
S El Chehadeh, R Touraine, F Prieur, W Reardon, T Bienvenu, S Chantot-Bastaraud, M Doco-Fenzy, E Landais, C Philippe, N Marle, P Callier, A-L Mosca-Boidron, F Mugneret, N Le Meur, A Goldenberg, A-M Guerrot, P Chambon, V Satre, C Coutton, P-S Jouk, F Devillard, K Dieterich, A Afenjar, L Burglen, M-L Moutard, M-C Addor, S Lebon, D Martinet, J-L Alessandri, B Doray, M Miguet, D Devys, P Saugier-Veber, S Drunat, B Aral, V Kremer, S Rondeau, A-C Tabet, J Thevenon, C Thauvin-Robinet, N Perreton, V Des Portes, L 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
https://www.readbyqxmd.com/read/27749765/trauma-induced-acute-x-chromosome-skewing-in-white-blood-cells-represents-an-immuno-modulatory-mechanism-unique-to-females-and-a-likely-contributor-to-sex-based-outcome-differences
#17
Geber Pena, Christina Michalski, Robert J Donnelly, Yong Qin, Ziad C Sifri, Anne C Mosenthal, David H 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. Thirty-nine 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...
April 2017: Shock
https://www.readbyqxmd.com/read/27716834/round-spermatid-injection-rescues-female-lethality-of-a-paternally-inherited-xist-deletion-in-mouse
#18
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
https://www.readbyqxmd.com/read/27542829/female-mice-lacking-xist-rna-show-partial-dosage-compensation-and-survive-to-term
#19
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
https://www.readbyqxmd.com/read/27528619/xist-and-tsix-transcription-dynamics-is-regulated-by-the-x-to-autosome-ratio-and-semistable-transcriptional-states
#20
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
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