Monk David, Smith Rachel, Arnaud Philippe, Preece Michael A, Stanier Philip, Beechey Colin V, Peters Jo, Kelsey Gavin, Moore Gudrun E
Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK.
Mamm Genome. 2003 Dec;14(12):805-16. doi: 10.1007/s00335-003-2287-7.
Proximal mouse Chromosome (Chr) 11 shares regions of orthology with the candidate gene region for the imprinting growth disorder Silver-Russell syndrome (SRS) on human Chr 7p. It has previously been shown that mice with two maternal or two paternal copies (duplications, Dp) of proximal Chr 11 exhibit reciprocal growth phenotypes. Those with two paternal copies show fetal and placental overgrowth, while those with two maternal copies are growth retarded. The growth retardation observed in the latter is reminiscent of the intrauterine growth restriction (IUGR) observed in SRS patients with maternal uniparental disomy for Chr 7 (mUPD7). We have carried out a methylation-sensitive representational difference analysis (Me-RDA) screen to look for regions of differential methylation (DMRs) associated with imprinted genes. For these experiments, we have used mouse embryos with uniparental duplications of Chrs 11 and 7 proximal to the breakpoint of the reciprocal translocation T(7;11)40Ad. Two previously known imprinted loci associated with paternal allele hypomethylation were recovered on proximal mouse Chr 11, U2af1-rs1 and Meg1/Grb10. These two genes map 15 cM apart, so it seems likely that they are within separate imprinted domains that do not contain additional DMRs. The known imprinted gene Peg3, located on mouse proximal Chr 7, was also detected in our screen. The finding that Peg3 was differentially methylated in embryos with uniparental inheritance of proximal Chr 7 confirms that Peg3 is located proximal to the breakpoint of T40Ad in G-band 7A2. Because GRB10 has previously been reported to be a candidate gene for SRS, we analysed 22 patients for epimutations of the GRB10 differentially methylated region that could lead to the altered expression of this gene. No such mutations were found.
小鼠近端11号染色体与人类7号染色体上印记生长障碍综合征（SRS）候选基因区域存在同源区域。此前研究表明，具有近端11号染色体两个母本或两个父本拷贝（重复，Dp）的小鼠表现出相反的生长表型。具有两个父本拷贝的小鼠表现出胎儿和胎盘过度生长，而具有两个母本拷贝的小鼠则生长迟缓。后者观察到的生长迟缓让人联想到7号染色体单亲二倍体（mUPD7）的SRS患者中观察到的宫内生长受限（IUGR）。我们进行了甲基化敏感代表性差异分析（Me-RDA）筛选，以寻找与印记基因相关的差异甲基化区域（DMR）。对于这些实验，我们使用了具有11号和7号染色体单亲重复的小鼠胚胎，这些染色体位于相互易位T(7;11)40Ad断点近端。在小鼠近端11号染色体上发现了两个先前已知的与父本等位基因低甲基化相关的印记位点，U2af1-rs1和Meg1/Grb10。这两个基因相距15厘摩，因此它们似乎位于不包含其他DMR的单独印记域内。在我们的筛选中还检测到了位于小鼠近端7号染色体上的已知印记基因Peg3。Peg3在近端7号染色体单亲遗传的胚胎中差异甲基化的发现证实，Peg3位于T40Ad断点近端的G带7A2区域。由于GRB10此前已被报道为SRS的候选基因，我们分析了22例患者GRB10差异甲基化区域的表观突变，这些突变可能导致该基因表达改变。未发现此类突变。
