Reproductive Medicine Center, Xiangya Hospital, Central South University, Changsha, 410078, Hunan, China.
Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China.
J Ovarian Res. 2022 Mar 30;15(1):38. doi: 10.1186/s13048-022-00971-9.
Oocyte maturation arrest at metaphase I leads to fertilization failure in humans. In early embryos, the tubulin beta 8 class VIII (TUBB8) encodes a β-tubulin isotype and aids in the assembling of the human oocyte spindle. Mutations in the TUBB8 potentially interfere with human oocyte maturation-a crucial prerequisite for fertilization and subsequent embryonic development. This study aims to investigate the novel mutations in TUBB8 and their prevalence.
Hundred fertile women (controls) and eleven infertile women with oocyte maturation arrest were chosen for the study. A total of five TUBB8 heterozygous/homozygous mutations were found in eleven infertile females (p.A313V, p.C239W, p.R251Q, p.P358L, and p.G96R). The Exome Aggregation Consortium (ExAC), SIFT, and PolyPhen-2 analyses revealed that p. A313V has unknown pathogenicity and p.C239W, p.R251Q, p.P358L, and p.G96R have possible pathogenicity. The wild-type (WT) and four mutant gene constructs were transfected to Hela cells. The Western blot analysis indicates that the TUBB8 expression of the p.C239W, p.R251Q, and p.G96R mutations was significantly decreased than that of WT. The immunofluorescence assay showed that the Hela cells transfected with either p.C239W, p.R251Q, or p.G96R mutations exhibited the disrupted microtubule structure, revealing a significant difference in the organization of the microtubule network compared to the WT.
We identified three novel variants and two reported variants out of 11 infertile women with oocyte metaphase I arrest. According to the present data, TUBB8 gene variants account for 31.96% of all participants (109/341) with oocyte maturation arrest.
人卵子在第一次减数分裂中期发生成熟阻滞会导致受精失败。在早期胚胎中，微管蛋白β 8 类 VIII（TUBB8）编码一种β-微管蛋白同工型，有助于组装人卵母细胞纺锤体。TUBB8 基因突变可能干扰人卵母细胞成熟——这是受精和随后胚胎发育的关键前提。本研究旨在研究 TUBB8 的新突变及其流行率。
选择了 11 名卵母细胞成熟阻滞的不孕妇女和 100 名正常生育的妇女进行研究。在 11 名不孕女性中发现了 5 个 TUBB8 杂合/纯合突变（p.A313V、p.C239W、p.R251Q、p.P358L 和 p.G96R）。外显子组聚合联盟（ExAC）、SIFT 和 PolyPhen-2 分析显示，p.A313V 具有未知的致病性，而 p.C239W、p.R251Q、p.P358L 和 p.G96R 具有可能的致病性。将野生型（WT）和 4 个突变基因构建体转染到 Hela 细胞中。Western blot 分析表明，p.C239W、p.R251Q 和 p.G96R 突变的 TUBB8 表达明显低于 WT。免疫荧光分析显示，转染 p.C239W、p.R251Q 或 p.G96R 突变的 Hela 细胞微管结构被破坏，微管网络的组织与 WT 相比有明显差异。
我们从 11 名卵母细胞中期阻滞的不孕妇女中鉴定出 3 个新突变和 2 个已报道的突变。根据目前的数据，TUBB8 基因突变占所有卵母细胞成熟阻滞患者的 31.96%（109/341）。
