摘要
Mammalian fertilization is triggered by a series of calcium (Ca2+) oscillations that are essential for egg activation and successful embryo development. It is widely accepted that Phospholipase C zeta (PLCζ) is the sperm-derived factor that triggers these oscillations, initiating egg activation through the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), leading to Ca2+ release. Several studies have reported a number of PLCζ mutations associated with polyspermy, egg activation failure and early embryonic arrest. Herein, six infertility-linked PLCζ mutations (I120M, L246F, L277P, S350P, A384V and M578T) spanning different domains of PLCζ were selected for characterization through in vivo assessment of their Ca2+-oscillation-inducing activities and complementary in silico analysis. Our data revealed that five of the investigated PLCζ mutants exhibited reduced or complete loss of in vivo Ca2+-oscillation-inducing activity, with the exception of the L277P, which resulted in increased frequency and duration of Ca2+ oscillations. Molecular modeling of PLCζ mutants was consistent with the in vivo characterization, revealing that most mutations have a deleterious effect on the structural stability. For the first time, we provide evidence that a gain-of-function PLCζ mutation may be a cause of fertilization failure in humans. Our findings suggest that PLCζ enzymatic activity must operate within an optimal range to ensure successful egg activation and early embryonic development. Additionally, we demonstrate the essential role of all PLCζ domains in maintaining the Ca2+ oscillation-inducing activity in eggs and the importance of PLCζ functionality in human fertilization.
摘要译文
哺乳动物受精是由一系列钙（CA2+）振荡引发的，这些振荡对于卵子激活和成功的胚胎发育至关重要。人们普遍认为，磷脂酶C Zeta（PLCζ）是触发这些振荡的精子衍生因素，通过将磷脂酰辛醇4,5-双磷酸磷酸盐（PIP2）的水解引起卵激活，从而在含量1,4,5-磷酸盐（ip3）+ diacycylglycerol（diagycylglyscerol（diacyl）中，并释放了卵。几项研究报道了许多与多工，卵激活失败和早期胚胎停滞有关的PLCζ突变。在此，选择了六个跨越不同域的不孕症的PLCζ突变（I120M，L246F，L277P，S350P，A384V和M578T），涵盖了不同的PLCζ域，以通过体内评估其Ca2+苏联诱导的活性和辅助活性和辅助分析中的体内评估来表征。我们的数据表明，除L277P外，研究的五个PLCζ突变体显示出体内Ca2+振荡活性的降低或完全损失，但L277P除外，导致Ca2+振荡的频率和持续时间增加。PLCζ突变体的分子模型与体内表征一致，表明大多数突变对结构稳定性具有有害作用。我们首次提供了证据表明，功能障碍PLCζ突变可能是人类受精衰竭的原因。我们的发现表明，PLCζ酶活性必须在最佳范围内发挥作用，以确保成功的鸡蛋激活和早期的胚胎发育。此外，我们证明了所有PLCζ结构域在维持卵中诱导Ca2+振荡活性以及PLCζ功能在人类受精中的重要性的重要作用。
Alaaeldin Saleh; Zizhen Huang; Maryam Al Shaikh; Tomasz P. Jurkowski; Zeyaul Islam; Karl Swann; Michail Nomikos. A Novel PLCζ Mutation Linked to Male Factor Infertility Induces a Gain-of-Function Effect on Ca2+ Oscillations in Eggs[J]. International Journal of Molecular Sciences, 2025,26(13): 6241