Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX, USA.
Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.
Reprod Sci. 2023 Sep;30(9):2780-2793. doi: 10.1007/s43032-023-01218-8. Epub 2023 Mar 28.
The subcortical maternal complex (SCMC) is a multiprotein complex in oocytes and preimplantation embryos that is encoded by maternal effect genes. The SCMC is essential for zygote-to-embryo transition, early embryogenesis, and critical zygotic cellular processes, including spindle positioning and symmetric division. Maternal deletion of Nlrp2, which encodes an SCMC protein, results in increased early embryonic loss and abnormal DNA methylation in embryos. We performed RNA sequencing on pools of meiosis II (MII) oocytes from wild-type and Nlrp2-null female mice that were isolated from cumulus-oocyte complexes (COCs) after ovarian stimulation. Using a mouse reference genome-based analysis, we found 231 differentially expressed genes (DEGs) in Nlrp2-null compared to WT oocytes (123 up- and 108 downregulated; adjusted p < 0.05). The upregulated genes include Kdm1b, a H3K4 histone demethylase required during oocyte development for the establishment of DNA methylation marks at CpG islands, including those at imprinted genes. The identified DEGs are enriched for processes involved in neurogenesis, gland morphogenesis, and protein metabolism and for post-translationally methylated proteins. When we compared our RNA sequencing data to an oocyte-specific reference transcriptome that contains many previously unannotated transcripts, we found 228 DEGs, including genes not identified with the first analysis. Interestingly, 68% and 56% of DEGs from the first and second analyses, respectively, overlap with oocyte-specific hyper- and hypomethylated domains. This study shows that there are substantial changes in the transcriptome of mouse MII oocytes from female mice with loss of function of Nlrp2, a maternal effect gene that encodes a member of the SCMC.
皮质下母性复合物 (SCMC) 是卵母细胞和植入前胚胎中的一种多蛋白复合物，由母体效应基因编码。SCMC 对于合子到胚胎的转变、早期胚胎发生和关键的合子细胞过程至关重要，包括纺锤体定位和对称分裂。编码 SCMC 蛋白的 Nlrp2 母源缺失会导致早期胚胎丢失增加和胚胎中异常的 DNA 甲基化。我们对从卵巢刺激后从卵丘-卵母细胞复合物 (COC) 中分离出来的野生型和 Nlrp2 缺失型雌性小鼠的减数分裂 II (MII) 卵母细胞进行了 RNA 测序。使用基于小鼠参考基因组的分析，我们发现 Nlrp2 缺失型与 WT 卵母细胞相比有 231 个差异表达基因 (DEGs)（123 个上调和 108 个下调；调整后的 p<0.05）。上调的基因包括 Kdm1b，这是一种 H3K4 组蛋白去甲基酶，在卵母细胞发育过程中对于在 CpG 岛建立 DNA 甲基化标记（包括印迹基因）是必需的。鉴定出的 DEGs 富集了参与神经发生、腺体形态发生和蛋白质代谢以及翻译后甲基化蛋白的过程。当我们将我们的 RNA 测序数据与包含许多以前未注释转录本的卵母细胞特异性参考转录组进行比较时，我们发现了 228 个 DEGs，其中包括第一次分析中未识别的基因。有趣的是，第一次和第二次分析的 DEGs 分别有 68%和 56%与卵母细胞特异性高和低甲基化区域重叠。这项研究表明，在功能丧失的 Nlrp2 母性效应基因（编码 SCMC 的成员）的雌性小鼠的 MII 卵母细胞中转录组有大量变化。
