Homozygous mutation of PLCZ1 leads to defective human oocyte activation and infertility that is not rescued by the WW-binding protein PAWP
Homozygous mutation of PLCZ1 leads to defective human oocyte activation and infertility that is not rescued by the WW-binding protein PAWP
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DOI：
10.1093/hmg/ddv617
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发表时间：
2016-03-01
影响因子：
3.5
通讯作者：
Arnoult, Christophe
中科院分区：
文献类型：
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作者：
Escoffier, Jessica;Lee, Hoi Chang;Arnoult, Christophe
在哺乳动物中，精子-卵母细胞融合引发Ca2+振荡，导致一系列称为卵母细胞激活的事件，这是胚胎发育的第一阶段。Ca2+信号是由精子传递的卵母细胞激活因子引起的。精子特异性磷脂酶C（PLCZ1）可能是诱导卵母细胞活化的候选物。最近，一种由WBP2NL编码的精子色氨酸结构域结合蛋白PAWP被提出具有相同的功能。在这里，我们研究了两个不育的兄弟，他们的精子形态正常，但在卵胞浆内单精子注射后完全受精失败。全外显子组测序证实PLCZ1， c.1465A . >T存在错义纯合突变；p.Ile489Phe，将il489转化为Phe。我们发现该突变是有害的，导致精子中蛋白质缺失，注射到小鼠GV和MII卵母细胞时蛋白质定位错误，高度异常的Ca2+瞬态和早期胚胎骤停。总的来说，这些改变与我们的患者精子无法诱导卵母细胞激活和启动胚胎发育是一致的。相比之下，WBP2NL中未发现有害变异，PAWP表达和定位正常。总的来说，我们证明，在人类中，PLCZ1的缺乏足以阻止卵母细胞的激活，而不管PAWP的存在。此外，它是位于PLCZ1 C2结构域的第一个突变，该结构域涉及将蛋白质靶向细胞膜。这为结构功能研究打开了大门，以确定C2结构域的保守氨基酸，这些氨基酸调节PLCZ1的靶向性及其对脂质底物的选择性。
In mammals, sperm-oocyte fusion initiates Ca2+ oscillations leading to a series of events called oocyte activation, which is the first stage of embryo development. Ca2+ signaling is elicited by the delivery of an oocyte-activating factor by the sperm. A sperm-specific phospholipase C(PLCZ1) has emerged as the likely candidate to induce oocyte activation. Recently, PAWP, a sperm-born tryptophan domain-binding protein coded by WBP2NL, was proposed to serve the same purpose. Here, we studied two infertile brothers exhibiting normal sperm morphology but complete fertilization failure after intracytoplasmic sperm injection. Whole exomic sequencing evidenced a missense homozygous mutation in PLCZ1, c.1465A>T; p.Ile489Phe, converting Ile 489 into Phe. We showed the mutation is deleterious, leading to the absence of the protein in sperm, mislocalization of the protein when injected in mouse GV and MII oocytes, highly abnormal Ca2+ transients and early embryonic arrest. Altogether these alterations are consistent with our patients' sperm inability to induce oocyte activation and initiate embryo development. In contrast, no deleterious variants were identified in WBP2NL and PAWP presented normal expression and localization. Overall we demonstrate in humans, the absence of PLCZ1 alone is sufficient to prevent oocyte activation irrespective of the presence of PAWP. Additionally, it is the first mutation located in the C2 domain of PLCZ1, a domain involved in targeting proteins to cell membranes. This opens the door to structure-function studies to identify the conserved amino acids of the C2 domain that regulate the targeting of PLCZ1 and its selectivity for its lipid substrate(s).