Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
J Neurochem. 2011 Aug;118(4):646-57. doi: 10.1111/j.1471-4159.2011.07273.x. Epub 2011 May 13.
Prenatal ethanol exposure causes significant neurodevelopmental deficits through its induction of apoptosis in neuronal progenitors including the neural crest. Using an established chick embryo model, we previously showed that clinically relevant ethanol concentrations cause neural crest apoptosis through mobilization of an intracellular calcium transient. How the calcium transient initiates this cell death is unknown. In this study, we identify CaMKII as the calcium target responsible for ethanol-induced apoptosis. Immunostaining revealed selective enrichment of activated phosphoCaMKII(Thr286) within ethanol-treated neural crest. CaMKII activation in response to ethanol was rapid (< 60 s) and robust, and CaMKII activity was increased 300% over control levels. Treatment with CaMKII-selective inhibitors but not those directed against CaMKIV or PKC completely prevented the cell death. Forced expression of dominant-negative CaMKII prevented ethanol's activation of CaMKII and prevented the ethanol-induced death, whereas constitutively active CaMKII in ethanol's absence significantly increased cell death to levels caused by ethanol treatment. In summary, CaMKII is the key signal that converts the ethanol-induced, short-lived Ca(i) (2+) transient into a long-lived cellular effector. This is the first identification of CaMKII as a critical mediator of ethanol-induced cell death. Because neural crest differentiates into several neuronal lineages, our findings offer novel insights into how ethanol disrupts early neurogenesis.
产前乙醇暴露通过诱导包括神经嵴在内的神经元前体细胞凋亡，导致显著的神经发育缺陷。我们之前使用已建立的鸡胚模型表明，临床相关浓度的乙醇通过动员细胞内钙瞬变引起神经嵴细胞凋亡。钙瞬变如何引发这种细胞死亡尚不清楚。在这项研究中，我们确定 CaMKII 是负责乙醇诱导凋亡的钙靶标。免疫染色显示，激活的磷酸化 CaMKII（Thr286）在乙醇处理的神经嵴中选择性富集。对乙醇的 CaMKII 激活非常迅速（<60s）且强烈，CaMKII 活性比对照水平增加 300%。用 CaMKII 选择性抑制剂处理而不是用针对 CaMKIV 或 PKC 的抑制剂处理可完全防止细胞死亡。强制表达显性失活的 CaMKII 可防止乙醇激活 CaMKII 并防止乙醇诱导的死亡，而在没有乙醇的情况下组成性激活 CaMKII 会显著增加细胞死亡，达到乙醇处理引起的水平。总之，CaMKII 是将乙醇诱导的短暂 Ca(i)（2+）瞬变转化为长期细胞效应器的关键信号。这是首次将 CaMKII 鉴定为乙醇诱导细胞死亡的关键介质。由于神经嵴分化为几种神经元谱系，我们的发现为乙醇如何破坏早期神经发生提供了新的见解。
