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This Article Full Text Free Full Text (PDF) Free Supplemental Data All Versions of this Article: fj.09-129619v1 23/8/2587    most recent Alert me when this article is cited Alert me if a correction is posted 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 Google Scholar Google Scholar Articles by Vizlin-Hodzic, D. Articles by Simonsson, T. Search for Related Content PubMed PubMed Citation Articles by Vizlin-Hodzic, D. Articles by Simonsson, T.

Developmental studies of Xenopus shelterin complexes: the message to reset telomere length is already present in the egg

Department of Biomedicine, Medical Biochemistry and Cell Biology Division, University of Gothenburg, Gothenburg, Sweden

¹ Correspondence: University of Gothenburg, Department of Biomedicine, Medical Biochemistry and Cell Biology Division, P.O. Box 440, SE 405 30 Gothenburg, Sweden. E-mail: tomas.simonsson{at}gu.se

The 6-protein complex shelterin protects the telomeres of human chromosomes. The recent discovery that telomeres are important for epigenetic gene regulation and vertebrate embryonic development calls for the establishment of model organisms to study shelterin and telomere function under normal developmental conditions. Here, we report the sequences of the shelterin-encoding genes in Xenopus laevis and its close relation Xenopus tropicalis. In vitro expression and biochemical characterization of the Xenopus shelterin proteins TRF1, TRF2, POT1, TIN2, RAP1, TPP1, and the shelterin accessory factor PINX1 indicate that all main functions of their human orthologs are conserved in Xenopus. The XlTRF1 and XtTRF1 proteins bind double-stranded telomeric DNA sequence specifically and interact with XlTIN2 and XtTIN2, respectively. Similarly, the XlTRF2 and XtTRF2 proteins bind double-stranded telomeric DNA and interact with XlRAP1 and XtRAP1, respectively, whereas the XlPOT1 and XtPOT1 proteins bind single-stranded telomeric DNA. Real-time PCR further reveals the gene expression profiles for telomerase and the shelterin genes during embryogenesis. Notably, the composition of shelterin and the formation of its subcomplexes appear to be temporally regulated during embryonic development. Moreover, unexpectedly high telomerase and shelterin gene expression during early embryogenesis may reflect a telomere length-resetting mechanism, similar to that reported for induced pluripotent stem cells and for animals cloned through somatic nuclear transfer.—Vizlin-Hodzic, D., Ryme, J., Simonsson, S., Simonsson, T. Developmental studies of Xenopus shelterin complexes: the message to reset telomere length is already present in the egg.

Key Words: telosome • differentiation • ES cell • iPS cell • quadruplex • cellular senescence