School of Life Science and Technology, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150001, China.
Department of Urology, School of Medicine, Xiang'an Hospital of Xiamen University, Xiamen University, Xiamen, 361000, China.
Cell Mol Life Sci. 2024 Oct 9;81(1):429. doi: 10.1007/s00018-024-05462-2.
The mammalian imprinted Dlk1-Dio3 domain contains multiple lncRNAs, mRNAs, the largest miRNA cluster in the genome and four differentially methylated regions (DMRs), and deletion of maternally expressed RNA within this locus results in embryonic lethality, but the mechanism by which this occurs is not clear. Here, we optimized the model of maternally expressed RNAs transcription termination in the domain and found that the cause of embryonic death was apoptosis in the embryo, particularly in the liver. We generated a mouse model of maternally expressed RNAs silencing in the Dlk1-Dio3 domain by inserting a 3 × polyA termination sequence into the Gtl2 locus. By analyzing RNA-seq data of mouse embryos combined with histological analysis, we found that silencing of maternally expressed RNAs in the domain activated apoptosis, causing vascular rupture of the fetal liver, resulting in hemorrhage and injury. Mechanistically, termination of Gtl2 transcription results in the silencing of maternally expressed RNAs and activation of paternally expressed genes in the interval, and it is the gene itself rather than the IG-DMR and Gtl2-DMR that causes the aforementioned phenotypes. In conclusion, these findings illuminate a novel mechanism by which the silencing of maternally expressed RNAs within Dlk1-Dio3 domain leads to hepatic hemorrhage and embryonic death through the activation of apoptosis.
哺乳动物印记的 Dlk1-Dio3 结构域包含多个长非编码 RNA、信使 RNA、基因组中最大的 miRNA 簇和四个差异甲基化区域 (DMR)，该基因座中母源表达 RNA 的缺失会导致胚胎致死，但发生这种情况的机制尚不清楚。在这里，我们优化了该结构域中母源表达 RNA 转录终止的模型，发现胚胎死亡的原因是胚胎凋亡，特别是肝脏中的凋亡。我们通过在 Gtl2 基因座中插入 3×polyA 终止序列，在 Dlk1-Dio3 结构域中生成了沉默母源表达 RNA 的小鼠模型。通过分析结合组织学分析的小鼠胚胎 RNA-seq 数据，我们发现该结构域中母源表达 RNA 的沉默会激活凋亡，导致胎儿肝脏血管破裂，从而导致出血和损伤。从机制上讲，Gtl2 转录的终止导致间隔区内母源表达 RNA 的沉默和父源表达基因的激活，导致上述表型的是基因本身，而不是 IG-DMR 和 Gtl2-DMR。总之，这些发现阐明了一个新的机制，即通过激活凋亡，Dlk1-Dio3 结构域中母源表达 RNA 的沉默会导致肝脏出血和胚胎死亡。
