Chromosome 5p deletion syndrome Video
Cri du Chat Syndrome Documentary chromosome 5p deletion syndromeCan: Chromosome 5p deletion syndrome
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Michael C. Golding, Lauren S. Magri, Liyue Zhang, Sarah A. Lalone, Michael J. Higgins, Mellissa R. Development 1 September ; 17 : — To understand the complex regulation of genomic imprinting it is important to determine how early embryos establish imprinted gene expression across large chromosomal domains.
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Long non-coding RNAs ncRNAs have been associated with the regulation of imprinting domains, yet their function remains undefined. Here, we investigated the mouse Kcnq1ot1 ncRNA and its role in imprinted gene regulation during preimplantation development by utilizing mouse embryonic and extra-embryonic stem cell models.
Our findings demonstrate that the Kcnq1ot1 ncRNA extends kb from the transcription start site. This is significant as it raises the possibility that transcription through downstream genes might play a role in their silencing, including Thwhich we demonstrate possesses maternal-specific expression during early development.
To distinguish between chromosome 5p deletion syndrome functional role for the transcript and properties inherent to transcription of long ncRNAs, we employed RNA interference-based technology to deplete Kcnq1ot1 transcripts.
We hypothesized that post-transcriptional depletion of Kcnq1ot1 ncRNA would lead to activation of normally maternal-specific protein-coding genes on the paternal chromosome. Post-transcriptional short hairpin RNA-mediated depletion in embryonic stem, trophoblast stem and extra-embryonic endoderm stem cells had no observable effect on the imprinted expression of genes within the domain, or on Kcnq1ot1 imprinting center DNA methylation, although a significant decrease in Kcnq1ot1 RNA signal volume in the nucleus was observed.
Description
These data support the argument that it is the act of transcription that plays a role in imprint maintenance during early development rather than a post-transcriptional role for the RNA itself. Genomic imprinting is syndrom specialized transcriptional regulatory chromosome 5p deletion syndrome that restricts expression to the maternally or paternally inherited allele Verona et al. Imprinted genes often cluster together in large domains that are coordinately regulated by cis-acting regions known as imprinting centers ICs or imprinting control regions ICRs. ICRs harbor gamete-derived parental allelic marks and are responsible for imprinted gene regulation over hundreds of kilobases in a bidirectional manner.
Interestingly, imprinting domains are associated with a non-coding RNA ncRNA that may regulate imprinted gene expression for the entire cluster Barlow and Bartolomei, This domain contains one paternally expressed ncRNA, Kcnq1ot1chromosome 5p deletion syndrome eight maternally expressed protein-coding genes, including Slc22a18 solute carrier family 22a, member 18Cdkn1c cyclin-dependent kinase inhibitor 1cKcnq1 potassium voltage-gated channel, KQT-like subfamily, member 1 and Ascl2 achaete-scute homolog 2 Fig. When methylated on the maternal allele, Kcnq1ot1 is silent Mancini-DiNardo et al. On the paternal allele, the ICR is unmethylated and Kcnq1ot1 is transcribed. Paternal deletion of the Kcnq1ot1 ICR results in domain-wide loss of imprinting, demonstrating broad control by the ICR of imprinted gene regulation Fitzpatrick et al.
MATERIALS AND METHODS
Activation of the normally silent paternal alleles of the protein-coding genes is also seen when Kcnq1ot1 is truncated, possibly indicating a functional role for the macro ncRNA in imprinted domain regulation Mancini-DiNardo et al. The mechanism by which Kcnq1ot1 represses the expression of genes located more than kb away is not chromosome 5p deletion syndrome understood, although various models have been proposed. These include a role for the ncRNA in nucleating silent chromatin, similar to Xist in X inactivation; a role for Kcnq1ot1 transcription in initiating chromatin silencing through transcriptional interference, repressive chromatin compartmentalization or chromatin looping; or a combination of these mechanisms Mancini-DiNardo et al. Important regulatory elements have been identified by mutational analysis but such studies do not differentiate between these various possibilities.
Truncation studies suggest that it is the transcript or transcription that has a role in silencing, as premature termination of Kcnq1ot1 results in the derepression of imprinted protein-coding genes within their domains Mancini-DiNardo et al.]
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