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A Mouse Model for Imprinting of the Human Retinoblastoma Gene

The human RB1 gene is imprinted due to integration of the PPP1R26P1 pseudogene into intron 2. PPP1R26P1 harbors the gametic differentially methylated region of the RB1 gene, CpG85, which is methylated in the female germ line. The paternally unmethylated CpG85 acts as promoter for the alternative tra...

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Autores principales: Tasiou, Vasiliki, Hiber, Michaela, Steenpass, Laura
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4537222/
https://www.ncbi.nlm.nih.gov/pubmed/26275142
http://dx.doi.org/10.1371/journal.pone.0134672
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author Tasiou, Vasiliki
Hiber, Michaela
Steenpass, Laura
author_facet Tasiou, Vasiliki
Hiber, Michaela
Steenpass, Laura
author_sort Tasiou, Vasiliki
collection PubMed
description The human RB1 gene is imprinted due to integration of the PPP1R26P1 pseudogene into intron 2. PPP1R26P1 harbors the gametic differentially methylated region of the RB1 gene, CpG85, which is methylated in the female germ line. The paternally unmethylated CpG85 acts as promoter for the alternative transcript 2B of RB1, which interferes with expression of full-length RB1 in cis. In mice, PPP1R26P1 is not present in the Rb1 gene and Rb1 is not imprinted. Assuming that the mechanisms responsible for genomic imprinting are conserved, we investigated if imprinting of mouse Rb1 can be induced by transferring human PPP1R26P1 into mouse Rb1. We generated humanized Rb1_PPP1R26P1 knock-in mice that pass human PPP1R26P1 through the mouse germ line. We found that the function of unmethylated CpG85 as promoter for an alternative Rb1 transcript and as cis-repressor of the main Rb1 transcript is maintained in mouse tissues. However, CpG85 is not recognized as a gametic differentially methylated region in the mouse germ line. DNA methylation at CpG85 is acquired only in tissues of neuroectodermal origin, independent of parental transmission of PPP1R26P1. Absence of CpG85 methylation in oocytes and sperm implies a failure of imprint methylation establishment in the germ line. Our results indicate that site-specific integration of a proven human gametic differentially methylated region is not sufficient for acquisition of DNA methylation in the mouse germ line, even if promoter function of the element is maintained. This suggests a considerable dependency of DNA methylation induction on the surrounding sequence. However, our model is suited to determine the cellular function of the alternative Rb1 transcript.
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spelling pubmed-45372222015-08-20 A Mouse Model for Imprinting of the Human Retinoblastoma Gene Tasiou, Vasiliki Hiber, Michaela Steenpass, Laura PLoS One Research Article The human RB1 gene is imprinted due to integration of the PPP1R26P1 pseudogene into intron 2. PPP1R26P1 harbors the gametic differentially methylated region of the RB1 gene, CpG85, which is methylated in the female germ line. The paternally unmethylated CpG85 acts as promoter for the alternative transcript 2B of RB1, which interferes with expression of full-length RB1 in cis. In mice, PPP1R26P1 is not present in the Rb1 gene and Rb1 is not imprinted. Assuming that the mechanisms responsible for genomic imprinting are conserved, we investigated if imprinting of mouse Rb1 can be induced by transferring human PPP1R26P1 into mouse Rb1. We generated humanized Rb1_PPP1R26P1 knock-in mice that pass human PPP1R26P1 through the mouse germ line. We found that the function of unmethylated CpG85 as promoter for an alternative Rb1 transcript and as cis-repressor of the main Rb1 transcript is maintained in mouse tissues. However, CpG85 is not recognized as a gametic differentially methylated region in the mouse germ line. DNA methylation at CpG85 is acquired only in tissues of neuroectodermal origin, independent of parental transmission of PPP1R26P1. Absence of CpG85 methylation in oocytes and sperm implies a failure of imprint methylation establishment in the germ line. Our results indicate that site-specific integration of a proven human gametic differentially methylated region is not sufficient for acquisition of DNA methylation in the mouse germ line, even if promoter function of the element is maintained. This suggests a considerable dependency of DNA methylation induction on the surrounding sequence. However, our model is suited to determine the cellular function of the alternative Rb1 transcript. Public Library of Science 2015-08-14 /pmc/articles/PMC4537222/ /pubmed/26275142 http://dx.doi.org/10.1371/journal.pone.0134672 Text en © 2015 Tasiou et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Tasiou, Vasiliki
Hiber, Michaela
Steenpass, Laura
A Mouse Model for Imprinting of the Human Retinoblastoma Gene
title A Mouse Model for Imprinting of the Human Retinoblastoma Gene
title_full A Mouse Model for Imprinting of the Human Retinoblastoma Gene
title_fullStr A Mouse Model for Imprinting of the Human Retinoblastoma Gene
title_full_unstemmed A Mouse Model for Imprinting of the Human Retinoblastoma Gene
title_short A Mouse Model for Imprinting of the Human Retinoblastoma Gene
title_sort mouse model for imprinting of the human retinoblastoma gene
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4537222/
https://www.ncbi.nlm.nih.gov/pubmed/26275142
http://dx.doi.org/10.1371/journal.pone.0134672
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