A genome-wide screen for modifiers of transgene variegation identifies genes with critical roles in development

Ashe, Alyson, Morgan, Daniel K., Whitelaw, Nadia, Bruxner, Timothy J., Vickaryous, Nicola K., Cox, Liza L., Butterfield, Natalie C., Wicking, Carol, Blewitt, Marnie E., Wilkins, Sarah J., Anderson, Gregory J., Cox, Timothy C. and Whitelaw, Emma (2008) A genome-wide screen for modifiers of transgene variegation identifies genes with critical roles in development. Genome Biology, 9 12: R182-1-R182-16. doi:10.1186/gb-2008-9-12-r182


Author Ashe, Alyson
Morgan, Daniel K.
Whitelaw, Nadia
Bruxner, Timothy J.
Vickaryous, Nicola K.
Cox, Liza L.
Butterfield, Natalie C.
Wicking, Carol
Blewitt, Marnie E.
Wilkins, Sarah J.
Anderson, Gregory J.
Cox, Timothy C.
Whitelaw, Emma
Title A genome-wide screen for modifiers of transgene variegation identifies genes with critical roles in development
Journal name Genome Biology   Check publisher's open access policy
ISSN 1474-760X
Publication date 2008-12-19
Year available 2008
Sub-type Article (original research)
DOI 10.1186/gb-2008-9-12-r182
Open Access Status DOI
Volume 9
Issue 12
Start page R182-1
End page R182-16
Total pages 16
Place of publication London, United Kingdom
Publisher Biomed Central
Language eng
Abstract Malignant melanomas often arise from nevi, which result from initial oncogene-induced hyperproliferation of melanocytes that are maintained in a CDKN2A/p16-mediated senescent state. Thus, genes that can bypass this senescence barrier are likely to contribute to melanoma development. We have performed a gain-of-function screen of 17,030 lentivirally expressed human open reading frames (ORFs) in a melanoma cell line containing an inducible p16 construct to identify such genes. Genes known to bypass p16-induced senescence arrest, including the human papilloma virus 18 E7 gene ( HPV18E7), and genes such as the p16-binding CDK6 with expected functions, as well as panel of novel genes, were identified, including high-mobility group box (HMGB) proteins. A number of these were further validated in two other models of p16-induced senescence. Tissue immunohistochemistry demonstrated higher levels of CDK6 in primary melanomas compared with normal skin and nevi. Reduction of CDK6 levels drove melanoma cells expressing functional p16 into senescence, demonstrating its contribution to bypass senescence.
Formatted abstract
Background:
Some years ago we established an N-ethyl-N-nitrosourea screen for modifiers of transgene variegation in the mouse and a preliminary description of the first six mutant lines, named MommeD1-D6, has been published. We have reported the underlying genes in three cases: MommeD1 is a mutation in SMC hinge domain containing 1 (Smchd1), a novel modifier of epigenetic gene silencing; MommeD2 is a mutation in DNA methyltransferase 1 (Dnmt1); and MommeD4 is a mutation in Smarca 5 (Snf2h), a known chromatin remodeler. The identification of Dnmt1 and Smarca5 attest to the effectiveness of the screen design.

Results:

We have now extended the screen and have identified four new modifiers, MommeD7-D10. Here we show that all ten MommeDs link to unique sites in the genome, that homozygosity for the mutations is associated with severe developmental abnormalities and that heterozygosity results in phenotypic abnormalities and reduced reproductive fitness in some cases. In addition, we have now identified the underlying genes for MommeD5 and MommeD10. MommeD5 is a mutation in Hdac1, which encodes histone deacetylase 1, and MommeD10 is a mutation in Baz1b (also known as Williams syndrome transcription factor), which encodes a transcription factor containing a PHD-type zinc finger and a bromodomain. We show that reduction in the level of Baz1b in the mouse results in craniofacial features reminiscent of Williams syndrome.

Conclusions:
These results demonstrate the importance of dosage-dependent epigenetic reprogramming in the development of the embryo and the power of the screen to provide mouse models to study this process.
Keyword Position-effect Variegation
Williams-Beuten-Syndrome
Nitrosourea enu Screens
Histone Deacetylase
Craniofacial Development
Epigenetic Inheritance
Coding Mutations
Agouti Locus
Human Hdac8
WSTF-ISWI
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID 12-1182
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Medicine Publications
 
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Created: Fri, 17 Apr 2009, 00:32:53 EST by Sarah Elliott on behalf of Faculty Of Health Sciences