HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 283, Issue 17, 11509-11515, April 25, 2008

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 283/17/11509    most recent M709805200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Strathdee, D. Articles by Clark, A. J. Search for Related Content PubMed PubMed Citation Articles by Strathdee, D. Articles by Clark, A. J. Social Bookmarking                      What's this?

Distal Transgene Insertion Affects CpG Island Maintenance during Differentiation^*

Douglas Strathdee¹, C. Bruce A. Whitelaw², and A. John Clark

From the Division of Gene Function and Development, Roslin Institute, Roslin, Midlothian EH25 9PS, United Kingdom

About half of all genes have a CpG island surrounding the promoter and transcription start site. Most promoter CpG islands are normally unmethylated in all tissues, irrespective of the expression level of the associated gene. Establishment of the appropriate patterns of DNA methylation in the genome is essential for normal development and patterns of gene expression. Aberrant methylation of CpG islands and silencing of the associated genes is frequently observed in cancer. One gene with a 5'-CpG island is cytoplasmic β-actin, which is an abundantly expressed protein and a major component of microfilaments. Inserting a βgeo cassette into the 3'-untranslated region of β-actin gene led to widespread but not ubiquitous lacZ expression in mice heterozygous for the modified β-actin allele. Surprisingly, embryos homozygous for this insertion died at mid-gestation. The modified β-actin allele was expressed in undifferentiated embryonic stem cells but was turned off as these cells differentiate in vitro and in vivo. We demonstrate that the insertion affects the maintenance of the methylation status of the CpG island of the modified β-actin allele in differentiated but not in undifferentiated embryonic cells. These data suggest that there is a two-step process to defining a CpG island, requiring both embryonic establishment and a signal that maintains the CpG island in differentiated cells. Furthermore, they indicate that features built into the CpG island are not sufficient to direct CpG island maintenance during differentiation.

Received for publication, November 30, 2007 , and in revised form, February 27, 2008.

^* This work was supported in part by Grant CAD04943 from the Biotechnology and Biological Sciences Research Council (BBSRC). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental "Materials and Methods," Figs. S1 and S2, and Table S1.

² Supported separately by the BBSRC.

This work is dedicated to the memory of John Clark, who is sadly missed.

¹ To whom correspondence should be addressed: Wellcome Trust Sanger Inst., Genome Campus, Hinxton Cambridge, Cambridgeshire CB10 1SA, United Kingdom. Tel.: 44-1223-495390; Fax: 44-1223-494919. E-mail: ds10{at}sanger.ac.uk.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				F. Senigl, J. Plachy, and J. Hejnar The Core Element of a CpG Island Protects Avian Sarcoma and Leukosis Virus-Derived Vectors from Transcriptional Silencing J. Virol., August 15, 2008; 82(16): 7818 - 7827. [Abstract] [Full Text] [PDF]