%0 Journal Article
%T Expression and loss of alleles in cultured mouse embryonic fibroblasts and stem cells carrying allelic fluorescent protein genes
%A Jon S Larson
%A Moying Yin
%A Jared M Fischer
%A Saundra L Stringer
%A James R Stringer
%J BMC Molecular Biology
%D 2006
%I BioMed Central
%R 10.1186/1471-2199-7-36
%X As a step in assessing the utility of this approach, we derived primary embryonic fibroblast populations and embryonic stem cell lines from mice that carried two different fluorescent protein genes as alleles at the chromosome 6 locus, ROSA26. Fluorescence activated cell sorting (FACS) showed that the vast majority of cells in each line expressed the two marker proteins at similar levels, and that populations exhibited expression noise similar to that seen in bacteria and yeast. Cells with a monochromatic phenotype were present at frequencies on the order of 10-4 and appeared to be produced at a rate of approximately 10-5 variant cells per mitosis. 45 of 45 stably monochromatic ES cell clones exhibited loss of the expected allele at the ROSA26 locus. More than half of these clones retained heterozygosity at a locus between ROSA26 and the centromere. Other clones exhibited LOH near the centromere, but were disomic for chromosome 6.Allelic fluorescent markers allowed LOH at the ROSA26 locus to be detected by FACS. LOH at this locus was usually not accompanied by LOH near the centromere, suggesting that mitotic recombination was the major cause of ROSA26 LOH. Dichromatic mouse embryonic cells provide a novel system for studying genetic/karyotypic stability and factors influencing expression from allelic genes. Similar approaches will allow these phenomena to be studied in tissues.During malignant progression, cells accumulate multiple genetic and epigenetic alterations that cause loss of at least one anti-oncogenic function. Such a loss can be caused by a variety of events including mutation and losses that take place at the chromosome level, e.g. loss of heterozygosity (LOH), which is a hallmark of numerous cancers [1-5]. Many cases of LOH are caused by mitotic recombination (MR) between homologous chromosomes [6]. LOH can also arise via uniparental disomy (UPD), a change that presumably begins with nondisjunction of sister chromatids, producing trisomy in a daughter
%U http://www.biomedcentral.com/1471-2199/7/36