Pre-mRNA Missplicing of Mcl-1 is Involved in Ethanol Induced Neurotoxicity

Mcl-1前体mRNA错剪接参与乙醇诱导的神经毒性 重度和慢性乙醇暴露可对成人大脑造成显著的结构和功能损伤。 发育中的神经系统更容易受到酒精的影响。产前乙醇暴露 在怀孕期间，酒精可能会导致胎儿酒精谱系障碍（FASD），其特征是畸形的 神经系统和智力迟钝。乙醇暴露最具破坏性的后果是 与神经元耗竭相关的神经毒性。阐明神经细胞凋亡的机制是至关重要的 以开发有效的治疗方法来克服乙醇诱导的神经病理学。 大脑中剪接变体的调节可以调节蛋白质功能，这可能最终影响行为 与酒精依赖和乙醇介导的神经毒性有关。有限数量的研究 表明基因的前mRNA剪接模式可能会改变，并参与行为改变， 与酗酒有关。由于饮酒与神经毒性有关，因此可能 在酒精中毒的发展过程中，生存因子和促生存因子的剪接改变可能有助于 神经毒性我们的初步数据表明，乙醇暴露可导致Mcl-1的前体mRNA错误剪接， Bcl-2家族的促生存成员，通过下调富含丝氨酸/精氨酸的 剪接因子1（SRSF 1）。Mcl-1的前体mRNA可以选择性剪接以去除外显子2， 产生Mcl-1的缩短形式，称为Mcl-1 S。而更长的基因产物Mcl-1 L增强细胞 在存活期间，选择性剪接的较短基因产物Mcl-1 S促进细胞凋亡。我们的初步数据显示 表明，乙醇暴露于神经元导致Mcl-1 L/Mcl-1 S的比例下降，有利于亲- 凋亡Mcl-1 S剪接超过抗凋亡Mcl-1 L同种型，表明Mcl-1 S可能在 与酒精消耗有关的神经毒性。因此，我们假设乙醇诱导的改变 富含丝氨酸/精氨酸的剪接因子的表达导致Mcl-1的错误剪接，这有助于乙醇- 介导的神经毒性。我们建议通过以下方式检验我们的假设：（i）调查乙醇的影响 暴露对富含丝氨酸/精氨酸的选择性剪接因子（SR家族蛋白）表达水平的影响， 神经元，（ii）确定乙醇暴露对Mcl-1和其他 候选抗凋亡和促凋亡基因，和（iii）检查SRSF 1和酒精诱导的细胞凋亡的作用。 通过利用遗传、生化和生物学方法研究Mcl-1亚型在神经毒性和神经功能中的作用， 神经生理学方法

Pre-mRNA missplicing of Mcl-1 is involved in ethanol induced neurotoxicity Heavy and chronic ethanol exposure can cause significant structural and functional damage to the adult brain. The developing nervous system is even more vulnerable to ethanol exposure. Prenatal exposure of ethanol during pregnancy can lead to fetal alcohol spectrum disorders (FASD), characterized by malformation of the nervous system and mental retardation. The most devastating consequence of ethanol exposure is the neurotoxicity associated with the depletion of neurons. It is crucial to elucidate mechanisms of neuroapoptosis in order to develop effective therapeutic approaches to overcome ethanol-induced neuropathologies. Regulation of splice variants in the brain can modulate protein functions, which may ultimately affect behaviors associated with alcohol dependence and ethanol-mediated neurotoxicity. Limited number of studies has shown that pre-mRNA splicing patterns of genes are potentially altered and involved in behavior changes associated with alcoholism. Since alcohol consumption is associated with neurotoxicity, it is possible that altered splicing of survival and pro-survival factors during the development of alcoholism may contribute to the neurotoxicity. Our preliminary data suggest that ethanol exposure can lead to pre-mRNA missplicing of Mcl-1, a pro-survival member of the Bcl-2 family, by downregulating the expression levels of serine/arginine rich splicing factor 1 (SRSF1). The pre-mRNA of Mcl-1 can be alternatively spliced to remove exon 2, which produces shortened form of Mcl-1, named Mcl-1S. While the longer gene product Mcl-1L enhances cell survival, the alternatively spliced shorter gene product Mcl-1S promotes apoptosis. Our preliminary data has indicated that ethanol exposure to neurons leads to a decrease in the ratio of Mcl-1L/Mcl-1S by favoring pro- apoptotic Mcl-1S splicing over anti-apoptotic Mcl-1L isoform suggesting that Mcl-1S may play a crucial role in neurotoxicity associated with alcohol consumption. Therefore, we hypothesize that ethanol-induced altered expression of serine/arginine rich splicing factors leads to missplicing of Mcl-1, which contributes to ethanol- mediated neurotoxicity. We propose to examine our hypothesis by (i) investigating the impact of ethanol exposure on expression levels of serine/arginine rich alternative splicing factors (SR family proteins) in neurons, (ii) determining the effect of ethanol exposure on alternative pre-mRNA splicing of Mcl-1 and other candidate antiapoptotic and proapoptotic genes, and (iii) examining the role of SRSF1 and alcohol-induced isoforms of Mcl-1 in neurotoxicity and neuronal functions by utilizing genetic, biochemical, and neurophysiological approach.