Convergent and divergent evolution of genomic imprinting in the marsupial Monodelphis domestica
Convergent and divergent evolution of genomic imprinting in the marsupial Monodelphis domestica
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DOI：
10.1186/1471-2164-13-394
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发表时间：
2012-08-16
期刊：
影响因子：
4.4
通讯作者：
Jirtle, Randy L.
中科院分区：
文献类型：
--
作者：
Das, Radhika;Anderson, Nathan;Jirtle, Randy L.
背景：基因组印迹是一种表观遗传现象，导致亲本特异性单等位基因表达。它被认为是在胎盘哺乳动物中进化的，以调节子代的宫内资源分配。结果：L3MBTL和HTR2A在灰短尾负鼠(Monodelphis Home Tica)中有印迹。Mest表达单等位基因转录本和双等位基因转录本，与真核生物一样。相比之下，Impact、COPG2和PLAGL1没有印记在负鼠体内。在负鼠的任何一个新的印迹区域中，都没有发现参与调控真兽类印迹的差异甲基化区域(DMR)。有趣的是，在印记IGF2R基因的第11内含子中发现了一种新的DMR，但这在真核生物中不是保守的。负鼠印记基因启动子区域的富集组蛋白修饰H3赖氨酸4二甲基化。结论：基因组印记现象在动物中是保守的，但在印记基因和DMR的数量和位置上在变种动物和真动物之间的显著差异表明两种动物之间的印记不完全保守。在负鼠的一个非保守位置发现了一个新的DMR，并首次在负鼠的印记基因座发现了组蛋白修饰，这表明基因组印记可能是在这两个Therian亚类的共同祖先中进化的，随后两个谱系的调控机制也有所不同。
Background: Genomic imprinting is an epigenetic phenomenon resulting in parent-of-origin specific monoallelic gene expression. It is postulated to have evolved in placental mammals to modulate intrauterine resource allocation to the offspring. In this study, we determined the imprint status of metatherian orthologues of eutherian imprinted genes.Results: L3MBTL and HTR2A were shown to be imprinted in Monodelphis domestica (the gray short-tailed opossum). MEST expressed a monoallelic and a biallelic transcript, as in eutherians. In contrast, IMPACT, COPG2, and PLAGL1 were not imprinted in the opossum. Differentially methylated regions (DMRs) involved in regulating imprinting in eutherians were not found at any of the new imprinted loci in the opossum. Interestingly, a novel DMR was identified in intron 11 of the imprinted IGF2R gene, but this was not conserved in eutherians. The promoter regions of the imprinted genes in the opossum were enriched for the activating histone modification H3 Lysine 4 dimethylation.Conclusions: The phenomenon of genomic imprinting is conserved in Therians, but the marked difference in the number and location of imprinted genes and DMRs between metatherians and eutherians indicates that imprinting is not fully conserved between the two Therian infra-classes. The identification of a novel DMR at a non-conserved location as well as the first demonstration of histone modifications at imprinted loci in the opossum suggest that genomic imprinting may have evolved in a common ancestor of these two Therian infra-classes with subsequent divergence of regulatory mechanisms in the two lineages.