女性不育涉及卵母细胞形态异常并产生大的第一极体(PB1)的遗传基础是什么?
MOS原癌基因中的纯合错义变体(c.791C>G)和复合错义变体(c.596A>T和c.875C>T),丝氨酸/苏氨酸激酶(MOS)(男性在线孟德尔遗传(OMIM)参考:190060;NM_005372.1)是导致卵母细胞形态异常的原因,并产生大的PB1导致女性不孕。
MOS,卵母细胞特异性基因,编码丝氨酸/苏氨酸蛋白激酶,该激酶直接磷酸化丝裂原活化蛋白激酶(MAPK)激酶(MEK)以激活卵母细胞中的MAPK(也称为细胞外信号调节激酶(ERK))信号级联。缺乏Mos的雌性小鼠仍然存活,但是由于卵母细胞对称分裂而不育,自发孤雌生殖激活和早期胚胎停滞。最近,两项独立的研究表明,早期胚胎停滞和片段化的女性不育症可能是由MOS的双等位基因突变引起的。然而,到目前为止,MOS变体与人类卵母细胞中大量PB1挤出的表型无关,从而导致女性不育症。
在2020年12月至2022年2月之间招募了两个以卵母细胞中存在大PB1为特征的独立不育家庭。
从受试者的外周血样品中提取基因组DNA用于全外显子组测序。通过Sanger测序验证谱系分析。然后,在HEK293细胞和小鼠卵母细胞中确定了MOS变体对MOS蛋白特性和ERK1/2激活的致病作用。
我们在MOS中发现了三种罕见的错觉变体,包括来自家庭1中患者1的纯合错义变体(c.791C>G)和来自家庭2中双胞胎姐妹的两个复合错义变体(c.596A>T和c.875C>T)。MOS变体在不育患者中遵循隐性遗传模式。所有三名患者在卵母细胞中都显示出高百分比的大PB1挤出。三种MOS变体不能激活卵母细胞和HEK293细胞中的MEK1/2和ERK1/2。此外,与野生型MOS相比,MOS变体降低了MOS蛋白水平并减弱了与MEK1的结合能力。在siMos处理后,野生型人MOS互补RNA(cRNA)的显微注射逆转了卵母细胞的对称分裂。相比之下,三种MOS变体没有显示出救援能力。
不适用。
由于人类卵母细胞样本的稀缺性和相关的伦理限制,我们无法对研究患者进行抢救。
我们的发现扩大了MOS变异导致女性不育的遗传和表型谱。我们的研究发现有助于早期遗传诊断卵母细胞形态异常,其特征为大PB1,最终导致女性不孕。
本研究得到了国家自然科学基金(82071640和82001633)的资助,浙江省自然科学基金(LD22C060001),浙江省医药卫生科技项目(WKJ-ZJ-2005),中国博士后科学基金(2020M682575和2021T140198),长沙市自然科学基金(kq2007022)和湖南省创新型省份建设资助(2019SK4012)。作者都没有宣布任何竞争利益。
不适用。
What is the genetic basis of female infertility involving abnormal oocyte morphology with the production of a large first polar body (PB1)?
The homozygous missense variant (c.791C>G) and compound missense variants (c.596A>T and c.875C>T) in MOS proto-oncogene, serine/threonine kinase (MOS) (Online Mendelian Inheritance in Man (OMIM) reference: 190060; NM_005372.1) are responsible for abnormal oocyte morphology with the production of a large PB1 to cause infertility in women.
MOS, an oocyte-specific gene, encodes a serine/threonine-protein kinase that directly phosphorylates mitogen-activated protein kinase (MAPK) kinase (MEK) to activate MAPK (also called extracellular-signal-regulated kinase (ERK)) signal cascade in the oocyte. Female mice lacking Mos remained viable, but infertile because of oocyte symmetric division, spontaneous parthenogenetic activation and early embryonic arrest. Recently, two independent studies demonstrated that female infertility with early embryonic arrest and fragmentation can be caused by biallelic mutations in MOS. However, so far, MOS variants have not been associated with the phenotype of large PB1 extrusion in human oocytes to contribute to female infertility.
Two independent infertile families characterized by the presence of large PB1 in oocytes were recruited between December 2020 and February 2022.
Genomic DNA was extracted from the peripheral blood samples of the subjects for whole-exome sequencing. Pedigree analysis was validated by Sanger sequencing. Then, the pathogenic effects of the MOS variants on MOS protein properties and ERK1/2 activation were determined in HEK293 cells and mouse oocytes.
We identified three rare missense variants in MOS, including a homozygous missense variant (c.791C>G) from Patient 1 in Family 1 and two compound missense variants (c.596A>T and c.875C>T) from twin sisters in Family 2. The MOS variants followed a recessive inheritance pattern in infertile patients. All three patients displayed a high percentage of large PB1 extrusion in the oocytes. The three MOS variants could not activate MEK1/2 and ERK1/2 in oocytes and HEK293 cells. In addition, when compared with wild-type MOS, the MOS variants decreased the MOS protein level and attenuated the binding capacity with MEK1. Microinjection of wild-type human MOS complementary RNAs (cRNAs) reversed the symmetric division of oocytes after siMos treatment. In contrast, the three MOS variants demonstrated no rescuing ability.
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Owing to the scarcity of human oocyte samples and the associated ethical restrictions, we could not perform the rescue attempt for the study patients.
Our findings expand the genetic and phenotypic spectrum of MOS variants in causing female infertility. Our study findings facilitate the early genetic diagnosis of abnormal oocyte morphology characterized as large PB1 that eventually causes infertility in women.
This study was supported by the National Natural Science Foundation of
China (82071640 and 82001633), Natural Science Foundation of Zhejiang Province (LD22C060001), the Key Projects Jointly Constructed by the Ministry and the Province of Zhejiang Medical and Health Science and Technology Project (WKJ-ZJ-2005),
China Postdoctoral Science Foundation (2020M682575 and 2021T140198), the Changsha Municipal Natural Science Foundation (kq2007022) and Hunan Provincial Grant for Innovative Province Construction (2019SK4012). None of the authors declare any competing interests.
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