Hara Satoshi, Muramatsu Akari, Terao Miho, Takada Shuji
Department of Systems Developmental Biology, National Research Institute for Child Health and Development, Tokyo, Japan.
Devision of Molecular Genetics & Epigenetics, Department of Biomolecular Science, Faculty of Medicine, Saga University, Saga, Japan.
PLoS One. 2025 May 22;20(5):e0324882. doi: 10.1371/journal.pone.0324882. eCollection 2025.
The expression of imprinted genes in the Dlk1-Dio3 domain is regulated by Dlk1-Meg3 intergenic DMR (IG-DMR), which is methylated in a parental-of-origin-specific manner. An unmethylated 4.1-kb region in the IG-DMR is essential for the maternal allele. Several molecular mechanisms have been proposed for the 4.1-kb region of IG-DMR; however, the sequence in the 4.1-kb region essential for imprinted gene expression is still unknown. To explore the sequence responsible for the IG-DMR in vivo, we generated mutant mice with a series of IG-DMR deletions. We observed that a deletion of the 2.7-kb region, including the IG-DMR transcriptional regulatory element (IGTRE), on the maternal allele causes IG-DMR dysfunction, resulting in perinatal lethality. At least two functional sequences exist in IGTRE that are functionally redundant in vivo, and the paternal transmission of a mutant allele, in which IGTRE was deleted together with a tandem repeat sequence in IG-DMR (IGRep), rescued embryonic lethality due to a lack of paternal IGRep. Our findings revealed that a sequence responsible for the lethal phenotype of the maternally inherited 4.1-kb deletion of IG-DMR is in the IGTRE domain.
Dlk1-Dio3 区域中印迹基因的表达受 Dlk1-Meg3 基因间差异甲基化区域（IG-DMR）调控，该区域以亲本来源特异性方式发生甲基化。IG-DMR 中一个未甲基化的 4.1kb 区域对母本等位基因至关重要。针对 IG-DMR 的 4.1kb 区域已提出多种分子机制；然而，对于印迹基因表达至关重要的 4.1kb 区域中的序列仍然未知。为了在体内探索负责 IG-DMR 的序列，我们构建了一系列具有 IG-DMR 缺失的突变小鼠。我们观察到，母本等位基因上一个包括 IG-DMR 转录调控元件（IGTRE）的 2.7kb 区域的缺失会导致 IG-DMR 功能障碍，从而导致围产期致死。IGTRE 中至少存在两个在体内功能冗余的功能序列，并且一个突变等位基因的父本传递（其中 IGTRE 与 IG-DMR 中的串联重复序列（IGRep）一起被删除）挽救了由于缺乏父本 IGRep 导致的胚胎致死。我们的研究结果表明，负责母本遗传的 IG-DMR 4.1kb 缺失致死表型的序列位于 IGTRE 结构域中。
