Escoffier Jessica, Yassine Sandra, Lee Hoi Chang, Martinez Guillaume, Delaroche Julie, Coutton Charles, Karaouzène Thomas, Zouari Raoudha, Metzler-Guillemain Catherine, Pernet-Gallay Karin, Hennebicq Sylviane, Ray Pierre F, Fissore Rafael, Arnoult Christophe
Université Grenoble Alpes, Grenoble F-38000, France Equipe 'Andrologie, Génétique et Cancer' Laboratoire AGIM, CNRS FRE3405, La Tronche F-38700, France.
Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, 661 North Pleasant Street, Amherst, MA 01003, USA.
Mol Hum Reprod. 2015 Feb;21(2):157-68. doi: 10.1093/molehr/gau098. Epub 2014 Oct 29.
We recently identified the DPY19L2 gene as the main genetic cause of human globozoospermia (70%) and described that Dpy19l2 knockout (KO) mice faithfully reproduce the human phenotype of globozoospermia making it an excellent model to characterize the molecular physiopathology of globozoospermia. Recent case studies on non-genetically characterized men with globozoospermia showed that phospholipase C, zeta (PLCζ), the sperm factor thought to induce the Ca(2+) oscillations at fertilization, was absent from their sperm, explaining the poor fertilization potential of these spermatozoa. Since 30% of globozoospermic men remain genetically uncharacterized, the absence of PLCζ in DPY19L2 globozoospermic men remains to be formally established. Moreover, the precise localization of PLCζ and the reasons underlying its loss during spermatogenesis in globozoospermic patients are still not understood. Herein, we show that PLCζ is absent, or its presence highly reduced, in human and mouse sperm with DPY19L2-associated globozoospermia. As a consequence, fertilization with sperm from Dpy19l2 KO mice failed to initiate Ca(2+) oscillations and injected oocytes remained arrested at the metaphase II stage, although a few human oocytes injected with DPY19L2-defective sperm showed formation of 2-pronuclei embryos. We report for the first time the subcellular localization of PLCζ in control human sperm, which is along the inner acrosomal membrane and in the perinuclear theca, in the area corresponding to the equatorial region. Because these cellular components are absent in globozoospermic sperm, the loss of PLCζ in globozoospermic sperm is thus consistent and reinforces the role of PLCζ as an oocyte activation factor necessary for oocyte activation. In our companion article, we showed that chromatin compaction during spermiogenesis in Dpy19l2 KO mouse is defective and leads to sperm DNA damage. Together, these defects explain the poor fertilization potential of DPY19L2-globozoospermic sperm and the compromised developmental potential of embryos obtained using sperm from patients with a deletion of the DPY19L2 gene.
我们最近鉴定出DPY19L2基因是人类圆头精子症的主要遗传病因（70%），并描述了Dpy19l2基因敲除（KO）小鼠忠实地再现了人类圆头精子症的表型，使其成为表征圆头精子症分子生理病理学的优秀模型。最近对非基因特征明确的圆头精子症男性的病例研究表明，磷脂酶Cζ（PLCζ），即被认为在受精时诱导Ca(2+)振荡的精子因子，在他们的精子中不存在，这解释了这些精子受精潜力差的原因。由于30%的圆头精子症男性的遗传特征仍未明确，DPY19L2圆头精子症男性中PLCζ的缺失仍有待正式确定。此外，PLCζ的确切定位以及在圆头精子症患者精子发生过程中其缺失的原因仍不清楚。在此，我们表明，在与DPY19L2相关的圆头精子症的人类和小鼠精子中，PLCζ不存在或其存在大幅减少。因此，用Dpy19l2 KO小鼠的精子受精未能引发Ca(2+)振荡，注射的卵母细胞停滞在中期II阶段，尽管少数注射了DPY1缺乏精子的人类卵母细胞显示形成了双原核胚胎。我们首次报告了PLCζ在对照人类精子中的亚细胞定位，它沿着顶体内膜并在核周膜中，位于对应赤道区域的部位。由于这些细胞成分在圆头精子症精子中不存在，因此圆头精子症精子中PLCζ的缺失是一致的，并强化了PLCζ作为卵母细胞激活所必需的卵母细胞激活因子的作用。在我们的配套文章中，我们表明Dpy19l2 KO小鼠精子发生过程中的染色质浓缩存在缺陷，并导致精子DNA损伤。总之，这些缺陷解释了DPY19L2圆头精子症精子受精潜力差以及使用DPY19L2基因缺失患者的精子获得的胚胎发育潜力受损的原因。
