skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Remodeling of ribosomal genes in somatic cells by Xenopus egg extract

Abstract

Highlights: {yields} Xenopus egg extract remodels nuclei and alter cell growth characteristics. {yields} Ribosomal genes are reprogrammed within 6 h after extract exposure. {yields} rDNA reprogramming involves promoter targeting of SNF2H remodeling complex. {yields} Xenopus egg extract does not initiate stress-related response in somatic cells. {yields} Aza-cytidine elicits a stress-induced response in reprogrammed cells. -- Abstract: Extracts from Xenopus eggs can reprogram gene expression in somatic nuclei, however little is known about the earliest processes associated with the switch in the transcriptional program. We show here that an early reprogramming event is the remodeling of ribosomal chromatin and gene expression. This occurs within hours of extract treatment and is distinct from a stress response. Egg extract elicits remodeling of the nuclear envelope, chromatin and nucleolus. Nucleolar remodeling involves a rapid and stable decrease in ribosomal gene transcription, and promoter targeting of the nucleolar remodeling complex component SNF2H without affecting occupancy of the transcription factor UBF and the stress silencers SUV39H1 and SIRT1. During this process, nucleolar localization of UBF and SIRT1 is not altered. On contrary, azacytidine pre-treatment has an adverse effect on rDNA remodeling induced by extract and elicits a stress-type nuclear response. Thus, an early event of Xenopusmore » egg extract-mediated nuclear reprogramming is the remodeling of ribosomal genes involving nucleolar remodeling complex. Condition-specific and rapid silencing of ribosomal genes may serve as a sensitive marker for evaluation of various reprogramming methods.« less

Authors:
 [1];  [2];  [2]; ;  [1];  [3];  [2]
  1. Institute of Basic Animal and Veterinary Sciences, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C (Denmark)
  2. (Norway)
  3. Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo (Norway)
Publication Date:
OSTI Identifier:
22207479
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 412; Journal Issue: 3; Other Information: Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; BIOLOGICAL STRESS; CHROMATIN; CYTIDINE; EGGS; EVALUATION; GENES; PROMOTERS; SOMATIC CELLS; TRANSCRIPTION; TRANSCRIPTION FACTORS

Citation Formats

Ostrup, Olga, E-mail: osvarcova@gmail.com, Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norwegian Center for Stem Cell Research, Oslo, Hyttel, Poul, Klaerke, Dan A., Collas, Philippe, E-mail: philc@medisin.uio.no, and Norwegian Center for Stem Cell Research, Oslo. Remodeling of ribosomal genes in somatic cells by Xenopus egg extract. United States: N. p., 2011. Web. doi:10.1016/J.BBRC.2011.07.128.
Ostrup, Olga, E-mail: osvarcova@gmail.com, Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norwegian Center for Stem Cell Research, Oslo, Hyttel, Poul, Klaerke, Dan A., Collas, Philippe, E-mail: philc@medisin.uio.no, & Norwegian Center for Stem Cell Research, Oslo. Remodeling of ribosomal genes in somatic cells by Xenopus egg extract. United States. doi:10.1016/J.BBRC.2011.07.128.
Ostrup, Olga, E-mail: osvarcova@gmail.com, Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norwegian Center for Stem Cell Research, Oslo, Hyttel, Poul, Klaerke, Dan A., Collas, Philippe, E-mail: philc@medisin.uio.no, and Norwegian Center for Stem Cell Research, Oslo. Fri . "Remodeling of ribosomal genes in somatic cells by Xenopus egg extract". United States. doi:10.1016/J.BBRC.2011.07.128.
@article{osti_22207479,
title = {Remodeling of ribosomal genes in somatic cells by Xenopus egg extract},
author = {Ostrup, Olga, E-mail: osvarcova@gmail.com and Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo and Norwegian Center for Stem Cell Research, Oslo and Hyttel, Poul and Klaerke, Dan A. and Collas, Philippe, E-mail: philc@medisin.uio.no and Norwegian Center for Stem Cell Research, Oslo},
abstractNote = {Highlights: {yields} Xenopus egg extract remodels nuclei and alter cell growth characteristics. {yields} Ribosomal genes are reprogrammed within 6 h after extract exposure. {yields} rDNA reprogramming involves promoter targeting of SNF2H remodeling complex. {yields} Xenopus egg extract does not initiate stress-related response in somatic cells. {yields} Aza-cytidine elicits a stress-induced response in reprogrammed cells. -- Abstract: Extracts from Xenopus eggs can reprogram gene expression in somatic nuclei, however little is known about the earliest processes associated with the switch in the transcriptional program. We show here that an early reprogramming event is the remodeling of ribosomal chromatin and gene expression. This occurs within hours of extract treatment and is distinct from a stress response. Egg extract elicits remodeling of the nuclear envelope, chromatin and nucleolus. Nucleolar remodeling involves a rapid and stable decrease in ribosomal gene transcription, and promoter targeting of the nucleolar remodeling complex component SNF2H without affecting occupancy of the transcription factor UBF and the stress silencers SUV39H1 and SIRT1. During this process, nucleolar localization of UBF and SIRT1 is not altered. On contrary, azacytidine pre-treatment has an adverse effect on rDNA remodeling induced by extract and elicits a stress-type nuclear response. Thus, an early event of Xenopus egg extract-mediated nuclear reprogramming is the remodeling of ribosomal genes involving nucleolar remodeling complex. Condition-specific and rapid silencing of ribosomal genes may serve as a sensitive marker for evaluation of various reprogramming methods.},
doi = {10.1016/J.BBRC.2011.07.128},
journal = {Biochemical and Biophysical Research Communications},
number = 3,
volume = 412,
place = {United States},
year = {Fri Sep 02 00:00:00 EDT 2011},
month = {Fri Sep 02 00:00:00 EDT 2011}
}
  • The mechanisms governing nuclear reprogramming have not been fully elucidated yet; however, recent studies show a universally conserved ability of both oocyte and egg components to reprogram gene expression in somatic cells. The activation of genes associated with pluripotency by oocyte/egg components may require the remodeling of nuclear structures, such that they can acquire the features of early embryos and pluripotent cells. Here, we report on the remodeling of the nuclear lamina of mammalian cells by Xenopus oocyte and egg extracts. Lamin A/C is removed from somatic cells incubated in oocyte and egg extracts in an active process that requiresmore » permeable nuclear pores. Removal of lamin A/C is specific, since B-type lamins are not changed, and it is not dependent on the incorporation Xenopus egg specific lamin III. Moreover, transcriptional activity is differentially regulated in somatic cells incubated in the extracts. Pol I and II transcriptions are maintained in cells in oocyte extracts; however, both activities are abolished in egg extracts. Our study shows that components of oocyte and egg extracts can modify the nuclear lamina of somatic cells and that this nuclear remodeling induces a structural change in the nucleus which may have implications for transcriptional activity. These experiments suggest that modifications in the nuclear lamina structure by the removal of somatic proteins and the incorporation of oocyte/egg components may contribute to the reprogramming of somatic cell nuclei and may define a characteristic configuration of pluripotent cells.« less
  • A new method of mapping transcriptionally active genes of ribosomal proteins onto human chromosomes is proposed. The method is based on the detection of the expression of human ribosomal protein mRNA in rodent-human hybrid cells carrying different human chromosomes. Using this method, the functional gene of the human ribosomal protein S17 was mapped on chromosome 15 and the location of the S14 ribosomal protein gene on chromosome 5 was confirmed. 11 refs., 2 figs., 2 tabs.
  • Replication-defective vectors derived from reticuloendotheliosis virus were used to transduce exogenous genes into early somatic stem cells of the chicken embryo. One of these vectors transduced and expressed the chicken growth hormone coding sequence. The helper cell line, C3, was used to generate stocks of vector containing about 10/sup 4/ transducing units per ml. Injection of 5- to 20-..mu..l volumes of vector directly beneath the blastoderm of unincubated chicken embryos led to infection of somatic stem cells. Infected embryos and adults contained unrearranged integrated proviral DNAs. Embryos expressed the transduced chicken growth hormone gene and contained high levels of serummore » growth hormone. Blood, brain, muscle, testis, and semen contained from individuals injected as embryos contained vector DNA. Replication-defective vectors of the reticuloendotheliosis virus transduced exogenous genes into chicken embryonic stem cells in vivo.« less
  • Gene Mosaic (Mos) of chromosome 3 of Drosophila melanogaster was located by means of dominant markers Ly, Sb, and Dr. This gene was shown to be located between Ly and Sb in the centromeric region (45-50 map units). An analysis of interaction between Mos and mwh genes in cis- and trans-heterozygotes showed a significant effect of the Mos gene on mutability (recombinogenesis) of chromosome mwh in somatic cells. In the cis heterozygote mwh Mos/++, the frequency of small mutant clones on wings of flies increased. In mwh/Mos heterozygotes, the Mos gene caused a significant reduction of dorsocentral and scutellar bristlesmore » (78% in mwh/Mos, 85% in mwh +/+ Mos, and 98% in mwh Mos/mwh +). 20 refs., 3 tabs.« less