Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Alcohol. 2009 Dec;43(8):627-34. doi: 10.1016/j.alcohol.2009.09.026.
Myelination occurs in the central nervous system of the human fetus, adolescents, and young adults. Ethanol interferes with myelination in part by altering the composition of the myelin sheath. Here we show that ethanol also affected the expression of the transcription factor c-Fos in differentiating oligodendrocytes (OLGs). Central glial-4 OLG progenitors were induced to differentiate in the absence and presence of 100 mM ethanol, and ethanol-caused changes in the levels of c-Fos and myelin basic protein (MBP) were determined by Western blot analysis at selected developmental stages. The relatively high c-Fos level in progenitors did not immediately decrease to a low level at the onset of differentiation but displayed a downregulation at a later developmental stage. Ethanol delayed the developmental c-Fos downregulation maintaining c-Fos at a 45% higher level at 2 days of differentiation (DoD). Ethanol also decreased the rate of the burst of MBP expression that occurred between 1 and 2 DoD, reducing the MBP level by 47% at 2 DoD. The ethanol-caused delays of c-Fos downregulation and MBP upregulation were both blocked by the protein kinase C (PKC) inhibitor bisindolylmaleimide I (BIM). Likewise, treatment of OLGs with a low 5-nM concentration of the PKC activator by 12-O-tetradecanoylphorbol-13-acetate mimicked the ethanol effects on the expression of both proteins, effects that were also counteracted by BIM. The results indicate that ethanol-caused delays of the stage-specific c-Fos downregulation and the inhibition of MBP expression both occur through a PKC-mediated mechanism. The ethanol-caused delay in c-Fos downregulation may disrupt normal timing for expression of genes involved in OLG differentiation, and the inhibited MBP expression may alter the myelin sheath composition.
髓鞘形成发生在人类胎儿、青少年和年轻成年人的中枢神经系统中。乙醇通过改变髓鞘的组成部分来干扰髓鞘形成。在这里，我们表明，乙醇还会影响分化少突胶质细胞（OLGs）中的转录因子 c-Fos 的表达。在不存在和存在 100mM 乙醇的情况下，诱导中枢神经胶质 4 少突胶质前体细胞分化，并通过 Western blot 分析在选定的发育阶段确定乙醇引起的 c-Fos 和髓鞘碱性蛋白（MBP）水平的变化。前体细胞中相对较高的 c-Fos 水平不会在分化开始时立即降低到低水平，而是在稍后的发育阶段下调。乙醇延迟了发育过程中 c-Fos 的下调，使分化后 2 天的 c-Fos 水平保持在较高水平，增加了 45%。乙醇还降低了 1 至 2 天分化期间 MBP 表达爆发的速度，使 2 天分化时的 MBP 水平降低了 47%。c-Fos 下调和 MBP 上调的乙醇引起的延迟均被蛋白激酶 C（PKC）抑制剂双吲哚马来酰亚胺 I（BIM）阻断。同样，用 12-O-十四烷酰佛波醇-13-乙酸酯处理 OLGs，使其浓度为 5nM 的低 PKC 激活剂，模拟了乙醇对这两种蛋白表达的影响，这些影响也被 BIM 抵消。结果表明，乙醇引起的特定阶段 c-Fos 下调延迟和 MBP 表达抑制均通过 PKC 介导的机制发生。乙醇引起的 c-Fos 下调延迟可能会破坏与 OLG 分化相关的基因表达的正常时间，而抑制的 MBP 表达可能会改变髓鞘的组成。
