Carpinelli MR, Hilton DJ, Metcalf D, Antonchuk JL, Hyland CD, Mifsud SL et al.. Suppressor screen in Mpl-/- mice: c-Myb mutation causes supraphysiologic production of platelets in the absence of thrombopoietin signaling. Proc Natl Acad Sci USA 101: 6553-6558

The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville VIC 3052, Australia.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 05/2004; 101(17):6553-8. DOI: 10.1073/pnas.0401496101
Source: PubMed


Genetic screens in lower organisms, particularly those that identify modifiers of preexisting genetic defects, have been used successfully to order components of complex signaling pathways. To date, similar suppressor screens have not been used in vertebrates. To define the molecular pathways regulating platelet production, we have executed a large-scale modifier screen with genetically thrombocytopenic Mpl(-/-) mice by using N-ethyl-N-nitrosourea mutagenesis. Here we show that mutations in the c-Myb gene cause a myeloproliferative syndrome and supraphysiological expansion of megakaryocyte and platelet production in the absence of thrombopoietin signaling. This screen demonstrates the utility of large-scale N-ethyl-N-nitrosourea mutagenesis suppressor screens in mice for the simultaneous discovery and in vivo validation of targets for therapeutic discovery in diseases for which mouse models are available.

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Available from: Tracy Willson, Apr 16, 2014
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    • "c-Myb-/flox mice have 5-10% of normal c-Myb protein expression [83]. cThe ENU induced Plt4 mutation equates to c-Myb V384D [90]. dTotal lymphocyte count from peripheral blood given, but not split out into B and T cells [90]. "
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    ABSTRACT: Adult blood cell production or definitive hematopoiesis requires the transcription factor c-Myb. The closely related KAT3 histone acetyltransferases CBP (CREBBP) and p300 (EP300) bind c-Myb through their KIX domains and mice homozygous for a p300 KIX domain mutation exhibit multiple blood defects. Perplexingly, mice homozygous for the same KIX domain mutation in CBP have normal blood. Here we test the hypothesis that the CBP KIX domain contributes subordinately to hematopoiesis via a genetic interaction with c-Myb. We assessed hematopoiesis in mice bearing compound mutations of c-Myb and/or the KIX domains of CBP and p300, and measured the effect of KIX domain mutations on c-Myb-dependent gene expression. We found that in the context of a p300 KIX mutation, the CBP KIX domain mutation affects platelets, B cells, T cells, and red cells. Gene interaction (epistasis) analysis provides mechanistic evidence that blood defects in KIX mutant mice are consistent with reduced c-Myb and KIX interaction. Lastly, we demonstrated that the CBP and p300 KIX domains contribute to both c-Myb-dependent gene activation and repression. Together these results suggest that the KIX domains of CBP, and especially p300, are principal mediators of c-Myb-dependent gene activation and repression that is required for definitive hematopoiesis.
    PLoS ONE 12/2013; 8(12):e82684. DOI:10.1371/journal.pone.0082684 · 3.23 Impact Factor
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    • "Homozygotes of either Myb D152V mutation or Myb D384V mutation produced a supraphysiological expansion of MKs and their progenitors and platelet production in Thpo )/) mice (Carpinelli et al, 2004; Metcalf et al, 2005). The Myb M303V mutation results in thrombocytosis and megakaryocytosis, which reduced the transcriptional activity of MYB by 50%, directly correlating with reduced association with Ep300 (Carpinelli et al, 2004; Sandberg et al, 2005; Szalai et al, 2006). Interestingly, a model has been developed that places MYB as a switch that influences the lineage fate decision of bipotential MEPs, with high MYB levels favouring erythroid development, and low MYB levels resulting in a megakaryocytic fate (Mukai et al, 2006). "
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    ABSTRACT: Megakaryocytopoiesis is governed by a complex network of haematopoietic growth factors that regulate the different stages of the process, in which haematopoietic stem cells undergo megakaryocytic lineage commitment, proliferation, maturation, and functional activation to produce platelets. MicroRNAs (miRNA) are a class of about 22-nucleotide noncoding RNAs that have been highly conserved during evolution and play a significant role in haematopoiesis, including differentiation and lineage commitment of megakaryocyte. This review summarizes the miRNAs which have changed expression during megakaryocytopoiesis, and their positive and negative functions on megakaryocytic differentiation. In addition, the abnormal miRNA expression profiles in megakaryocytic disorders are reviewed.
    British Journal of Haematology 09/2011; 155(3):298-307. DOI:10.1111/j.1365-2141.2011.08859.x · 4.71 Impact Factor
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    • "As it has been successfully shown in lower organisms such as Drosophila melanogaster, Caenorhabditis elegans and Saccharomyces cerevisiae (Loo et al., 1995; Raftery et al., 1995; Bach et al., 2003), modifier chemical mutagenesis screens are powerful genetic tools to define the relative contribution of signalling interactions to physiological processes. Recently, such a sensitised genetic system has been developed in mouse allowing a similar dissection of mammalian signalling pathways (Satterthwaite et al., 2000; Carpinelli et al., 2004; Rubio-Aliaga et al., 2007; Buac et al., 2008). In a commonly used type of genetic screen, organisms carrying a defined mutation affecting the process of interest are further mutagenised and screened for second-site mutations, or modifiers, that enhance or suppress the severity of the parental phenotype (Simon et al., 1991; Karim et al., 1996). "
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    ABSTRACT: Meat yield and quality are closely related to muscle development. The muscle characteristics mainly take place during embryonic and postnatal phases. Thus, genetic control of muscle development in early stages represents a significant stake to improve product quality and production efficiency. In bovine, several programmes have been developed to detect quantitative trait loci (QTL) affecting growth, carcass composition or meat quality traits. Such strategy is incontestably very powerful yet extremely cumbersome and costly when dealing with large animals such as ruminants. Furthermore, the fine mapping of the QTL remains a real challenge. Here, we proposed an alternative approach based on chemical mutagenesis in the mouse combined with comparative genomics to identify regions or genes controlling muscle development in cattle. At present, we isolated seven independent mouse lines of high interest. Two lines exhibit a hypermuscular phenotype, and the other five show various skeletomuscular phenotypes. Detailed characterisation of these mouse mutants will give crucial input for the identification and the mapping of genes that control muscular development. Our strategy will provide the opportunity to understand the function and control of genes involved in improvement of animal physiology.
    animal 04/2011; 5(5):663-71. DOI:10.1017/S1751731110002405 · 1.84 Impact Factor
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