Maternal inactivation of genes encoding components of the subcortical maternal complex (SCMC) and its associated member, PADI6, generally results in early embryo lethality. In humans, SCMC gene variants were found in the healthy mothers of children affected by multilocus imprinting disturbances (MLID). However, how the SCMC controls the DNA methylation required to regulate imprinting remains poorly defined. We generated a mouse line carrying a Padi6 missense variant that was identified in a family with Beckwith–Wiedemann syndrome and MLID. If homozygous in female mice, this variant resulted in interruption of embryo development at the two-cell stage. Single-cell multiomic analyses demonstrated defective maturation of Padi6 mutant oocytes and incomplete DNA demethylation, down-regulation of zygotic genome activation (ZGA) genes, up-regulation of maternal decay genes, and developmental delay in two-cell embryos developing from Padi6 mutant oocytes but little effect on genomic imprinting. Western blotting and immunofluorescence analyses showed reduced levels of UHRF1 in oocytes and abnormal localization of DNMT1 and UHRF1 in both oocytes and zygotes. Treatment with 5-azacytidine reverted DNA hypermethylation but did not rescue the developmental arrest of mutant embryos. Taken together, this study demonstrates that PADI6 controls both nuclear and cytoplasmic oocyte processes that are necessary for preimplantation epigenetic reprogramming and ZGA.

中文翻译：

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母体效应 Padi6 变异导致卵母细胞核和细胞质异常，以及胚胎中表观遗传重编程和合子基因组激活失败

编码皮质下母体复合体 (SCMC) 及其相关成员 PADI6 的基因的母体失活通常会导致早期胚胎死亡。在人类中，在受多位点印记干扰 (MLID) 影响的儿童的健康母亲中发现了 SCMC 基因变异。然而，SCMC 如何控制调节印记所需的 DNA 甲基化仍不清楚。我们培育了一个携带Padi6错义变异的小鼠品系，该变异在患有 Beckwith-Wiedemann 综合征和 MLID 的家族中被发现。如果在雌性小鼠中是纯合的，这种变异会导致两细胞阶段的胚胎发育中断。单细胞多组学分析表明Padi6突变卵母细胞成熟缺陷、DNA 去甲基化不完全、合子基因组激活 (ZGA) 基因下调、母体衰变基因上调以及 Padi6 突变卵母细胞发育成的两细胞胚胎发育迟缓但对基因组印迹影响不大。蛋白质印迹和免疫荧光分析显示卵母细胞中 UHRF1 水平降低，卵母细胞和受精卵中 DNMT1 和 UHRF1 定位异常。 5-氮杂胞苷治疗可恢复 DNA 高甲基化，但不能挽救突变胚胎的发育停滞。总而言之，这项研究表明 PADI6 控制着床前表观遗传重编程和 ZGA 所必需的核和细胞质卵母细胞过程。