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X inactivation in triploidy and trisomy: the search for autosomal transfactors that choose the active X15

X inactivation in triploidy and trisomy: the search for autosomal transfactors that choose the active X15
X inactivation in triploidy and trisomy: the search for autosomal transfactors that choose the active X15
Only one X chromosome functions in diploid human cells irrespective of the sex of the individual and the number of X chromosomes. Yet, as we show, more than one X is active in the majority of human triploid cells. Therefore, we suggest that (i) the active X is chosen by repression of its XIST locus, (ii) the repressor is encoded by an autosome and is dosage sensitive, and (iii) the extra dose of this key repressor enables the expression of more than one X in triploid cells. Because autosomal trisomies might help locate the putative dosage sensitive trans-acting factor, we looked for two active X chromosomes in such cells. Previously, we reported that females trisomic for 18 different human autosomes had only one active X and a normal inactive X chromosome. Now we report the effect of triplication of the four autosomes not studied previously; data about these rare trisomies - full or partial - were used to identify autosomal regions relevant to the choice of active X. We find that triplication of the entire chromosomes 5 and 11 and parts of chromosomes 1 and 19 is associated with normal patterns of X inactivation, excluding these as candidate regions. However, females with inherited triplications of 1p21.3-q25.3, 1p31 and 19p13.2-q13.33 were not ascertained. Thus, if a single key dose-sensitive gene induces XIST repression, it could reside in one of these locations. Alternatively, more than one dosage-sensitive autosomal locus is required to form the repressor complex.
metabolism, rna, genetic, genetics, comparative study, physiology, x chromosome, sex, human, gene expression regulation, research, x chromosome inactivation, animals, research support, chromosomes, trisomy, expression, trans-activators, polyploidy, report, x, dosage compensation, mice, male, untranslated, female, humans
1018-4813
153-162
Migeon, B.R.
10cb9924-a7ac-405d-9486-ef4ee902cedd
Pappas, K.
b2eecb4f-5977-4b31-b225-c1a2055bf9ac
Stetten, G.
31362757-d4c8-4728-957a-bb5f011887ca
Trunca, C.
b805ddba-8f00-4e46-94b4-2c0e4e338cda
Jacobs, P.A.
32993834-5b30-4706-a09b-640baf848c49
Migeon, B.R.
10cb9924-a7ac-405d-9486-ef4ee902cedd
Pappas, K.
b2eecb4f-5977-4b31-b225-c1a2055bf9ac
Stetten, G.
31362757-d4c8-4728-957a-bb5f011887ca
Trunca, C.
b805ddba-8f00-4e46-94b4-2c0e4e338cda
Jacobs, P.A.
32993834-5b30-4706-a09b-640baf848c49

Migeon, B.R., Pappas, K., Stetten, G., Trunca, C. and Jacobs, P.A. (2008) X inactivation in triploidy and trisomy: the search for autosomal transfactors that choose the active X15. European Journal of Human Genetics, 16 (2), 153-162. (doi:10.1038/sj.ejhg.5201944).

Record type: Article

Abstract

Only one X chromosome functions in diploid human cells irrespective of the sex of the individual and the number of X chromosomes. Yet, as we show, more than one X is active in the majority of human triploid cells. Therefore, we suggest that (i) the active X is chosen by repression of its XIST locus, (ii) the repressor is encoded by an autosome and is dosage sensitive, and (iii) the extra dose of this key repressor enables the expression of more than one X in triploid cells. Because autosomal trisomies might help locate the putative dosage sensitive trans-acting factor, we looked for two active X chromosomes in such cells. Previously, we reported that females trisomic for 18 different human autosomes had only one active X and a normal inactive X chromosome. Now we report the effect of triplication of the four autosomes not studied previously; data about these rare trisomies - full or partial - were used to identify autosomal regions relevant to the choice of active X. We find that triplication of the entire chromosomes 5 and 11 and parts of chromosomes 1 and 19 is associated with normal patterns of X inactivation, excluding these as candidate regions. However, females with inherited triplications of 1p21.3-q25.3, 1p31 and 19p13.2-q13.33 were not ascertained. Thus, if a single key dose-sensitive gene induces XIST repression, it could reside in one of these locations. Alternatively, more than one dosage-sensitive autosomal locus is required to form the repressor complex.

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More information

Published date: 2008
Keywords: metabolism, rna, genetic, genetics, comparative study, physiology, x chromosome, sex, human, gene expression regulation, research, x chromosome inactivation, animals, research support, chromosomes, trisomy, expression, trans-activators, polyploidy, report, x, dosage compensation, mice, male, untranslated, female, humans

Identifiers

Local EPrints ID: 60054
URI: http://eprints.soton.ac.uk/id/eprint/60054
ISSN: 1018-4813
PURE UUID: 0acacd5a-fbc6-4f41-bc23-2eeb896255d2

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Date deposited: 08 Sep 2008
Last modified: 15 Mar 2024 11:18

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Contributors

Author: B.R. Migeon
Author: K. Pappas
Author: G. Stetten
Author: C. Trunca
Author: P.A. Jacobs

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