PDF(Pubmed)
Abstract：
Prenatal alcohol exposure (PAE) causes cognitive impairment and a distinctive craniofacial dysmorphology, due in part to apoptotic losses of the pluripotent cranial neural crest cells (CNCs) that form facial bones and cartilage. We previously reported that PAE rapidly represses expression of >70 ribosomal proteins (padj = 10-E47). Ribosome dysbiogenesis causes nucleolar stress and activates p53-MDM2-mediated apoptosis. Using primary avian CNCs and the murine CNC line O9-1, we tested whether nucleolar stress and p53-MDM2 signaling mediates this apoptosis. We further tested whether haploinsufficiency in genes that govern ribosome biogenesis, using a blocking morpholino approach, synergizes with alcohol to worsen craniofacial outcomes in a zebrafish model. In both avian and murine CNCs, pharmacologically relevant alcohol exposure (20mM, 2hr) causes the dissolution of nucleolar structures and the loss of rRNA synthesis; this nucleolar stress persisted for 18-24hr. This was followed by reduced proliferation, stabilization of nuclear p53, and apoptosis that was prevented by overexpression of MDM2 or dominant-negative p53. In zebrafish embryos, low-dose alcohol or morpholinos directed against ribosomal proteins Rpl5a, Rpl11, and Rps3a, the Tcof homolog Nolc1, or mdm2 separately caused modest craniofacial malformations, whereas these blocking morpholinos synergized with low-dose alcohol to reduce and even eliminate facial elements. Similar results were obtained using a small molecule inhibitor of RNA Polymerase 1, CX5461, whereas p53-blocking morpholinos normalized craniofacial outcomes under high-dose alcohol. Transcriptome analysis affirmed that alcohol suppressed the expression of >150 genes essential for ribosome biogenesis. We conclude that alcohol causes the apoptosis of CNCs, at least in part, by suppressing ribosome biogenesis and invoking a nucleolar stress that initiates their p53-MDM2 mediated apoptosis. We further note that the facial deficits that typify PAE and some ribosomopathies share features including reduced philtrum, upper lip, and epicanthal distance, suggesting the facial deficits of PAE represent, in part, a ribosomopathy.
摘要：
产前酒精暴露（PAE）会导致认知障碍和独特的颅面畸形，部分是由于形成面部骨骼和软骨的多能颅神经c细胞（CNCs）的凋亡损失。我们先前报道了PAE快速抑制>70核糖体蛋白的表达(padj=10-E47)。核糖体异常生物生成引起核仁应激并激活p53-MDM2介导的细胞凋亡。使用原代禽类CNCs和鼠CNC系O9-1，我们测试了核仁应激和p53-MDM2信号是否介导了这种凋亡。我们进一步测试了控制核糖体生物发生的基因中的单倍体是否不足，使用阻断吗啉代的方法，在斑马鱼模型中与酒精协同作用使颅面结果恶化。在禽类和鼠类CNCs中，药理学相关的酒精暴露(20mM，2hr）导致核仁结构的溶解和rRNA合成的丧失；这种核仁应力持续18-24小时。其次是减少扩散，核p53的稳定，以及通过MDM2或显性阴性p53的过表达而阻止的细胞凋亡。在斑马鱼胚胎中,针对核糖体蛋白Rpl5a的低剂量酒精或吗啉代，Rpl11和Rps3a,Tcof同源物Nolc1或mdm2分别引起适度的颅面畸形，而这些阻断吗啉与低剂量酒精协同作用，以减少甚至消除面部元素。使用RNA聚合酶1的小分子抑制剂CX5461获得了类似的结果，而p53阻断吗啉代蛋白在高剂量酒精下标准化了颅面结果。转录组分析证实，酒精抑制了核糖体生物发生所必需的>150个基因的表达。我们得出的结论是酒精引起CNCs的凋亡，至少在某种程度上,通过抑制核糖体生物发生和调用启动p53-MDM2介导的细胞凋亡的核仁应激。我们进一步注意到，代表PAE和一些核糖体病的面部缺陷具有共同的特征，包括减少的hiltrum，上唇,和震中距离,表明PAE的面部缺陷代表，在某种程度上,核糖体病.
