Huang Yanping, Flentke George R, Smith Susan M
UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, USA.
UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, USA; Dept. Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC, USA.
Reprod Toxicol. 2024 Dec;130:108747. doi: 10.1016/j.reprotox.2024.108747. Epub 2024 Nov 7.
Prenatal alcohol exposure is a leading cause of permanent neurodevelopmental disability and can feature distinctive craniofacial deficits that partly originate from the apoptotic deletion of craniofacial progenitors, a stem cell lineage called the neural crest (NC). We recently demonstrated that alcohol causes nucleolar stress in NC through its suppression of ribosome biogenesis (RBG) and this suppression is causative in their p53/MDM2-mediated apoptosis. Here, we show that this nucleolar stress originates from alcohol's activation of AMPK, which suppresses TORC1 and the p70/S6K-mediated stimulation of RBG. Alcohol-exposed cells of the pluripotent, primary cranial NC line O9-1 were evaluated with respect to their S6K, TORC1, and AMPK activity. The functional impact of these signals with respect to RBG, p53, and apoptosis were assessed using gain-of-function constructs and small molecule mediators. Alcohol rapidly (<2 hr) increased pAMPK, pTSC2, and pRaptor, and reduced both total and pS6K in NC cells. These changes persisted for at least 12 hr to 18 hr following alcohol exposure. Attenuation of these signals via gain- or loss-of-function approaches that targeted AMPK, S6K, or TORC1 prevented alcohol's suppression of rRNA synthesis and the induction of p53-stimulated apoptosis. We conclude that alcohol induces ribosome dysbiogenesis and activates their p53/MDM2-mediated apoptosis via its activation of pAMPK, which in turn activates TSC2 and Raptor to suppress the TORC1/S6K-mediated promotion of ribosome biogenesis. This represents a novel mechanism underlying alcohol's neurotoxicity and is consistent with findings that TORC1/S6K networks are critical for cranial NC survival.
产前酒精暴露是永久性神经发育障碍的主要原因，其特征可能包括独特的颅面缺陷，部分源于颅面祖细胞（一种称为神经嵴（NC）的干细胞谱系）的凋亡性缺失。我们最近证明，酒精通过抑制核糖体生物合成（RBG）在NC中引起核仁应激，这种抑制在其p53/MDM2介导的凋亡中起因果作用。在这里，我们表明这种核仁应激源于酒精对AMPK的激活，AMPK抑制TORC1以及p70/S6K介导的RBG刺激。对多能性原发性颅神经嵴细胞系O9-1中酒精暴露的细胞进行了S6K、TORC1和AMPK活性评估。使用功能获得性构建体和小分子介质评估了这些信号对RBG、p53和凋亡的功能影响。酒精迅速（<2小时）增加了NC细胞中的pAMPK、pTSC2和pRaptor，并降低了总S6K和pS6K。这些变化在酒精暴露后持续至少12小时至18小时。通过针对AMPK、S6K或TORC1的功能获得或功能丧失方法减弱这些信号，可防止酒精对rRNA合成的抑制以及p53刺激的凋亡诱导。我们得出结论，酒精通过激活pAMPK诱导核糖体生物合成异常并激活其p53/MDM2介导的凋亡，pAMPK进而激活TSC2和Raptor以抑制TORC1/S6K介导的核糖体生物合成促进作用。这代表了酒精神经毒性的一种新机制，并且与TORC1/S6K网络对颅神经嵴存活至关重要的发现一致。
