Regulation of alcohol consumption by chromatin modification

描述（由申请人提供）：在之前的INIA（酒精中毒综合神经科学倡议）-West项目期间，应用遗传基因组学/表型学方法来鉴定啮齿动物中的候选基因，这些基因通过表达水平的变化导致消耗不同量酒精的倾向。一个这样的候选基因是Gnb 1（G蛋白β 1亚基，Gpi）。在近交系和重组近交系小鼠品系以及针对酒精消耗差异选择的小鼠品系中，Gpi蛋白的脑水平与酒精消耗水平呈负相关。用表达靶向Gnb 1的shRNA的慢病毒载体治疗小鼠，降低了DBA/2小鼠丘脑核中的Gpi水平，并增加了酒精消耗。Gpi作为与戈伊蛋白的二聚体，影响许多细胞内信号传导途径，并且还已报道与IIa类组蛋白脱乙酰酶（HDAC）4和5相互作用并改变其转录活性。HDAC通常通过修饰组蛋白抑制转录，并且IIa类HDAC可以在细胞核和细胞质之间穿梭，这可以调节其转录活性。特别是，直接Gpy-HDAC相互作用降低HDAC活性，因此具有调节其他基因转录的潜力。考虑到HDACS活性先前已被发现对于可卡因的奖励效应是至关重要的，并且HDAC抑制减少酒精消耗，推测Gpy-HDAC相互作用在酒精消耗中的作用。在降低低酒精消耗小鼠脑中的Gnb 1表达后，以及在抑制或降低高酒精消耗小鼠脑中的HDAC表达后，测量酒精消耗。为了评估Gpi和HDAC之间的联系，将在用RNAi降低Gpi后测定HDAC转录活性（转录物水平和启动子乙酰化）以及HDAC亚细胞定位。总体而言，该项目将研究分子机制，重点是染色质修饰，通过该修饰，先前确定的酒精消费/偏好候选基因影响可能构成该表型的转录网络。

DESCRIPTION (provided by applicant): During the previous INIA (Integrated Neurosciences Initiative on Alcoholism)-West project period a genetical genomic/phenomic approach was applied to identify candidate genes in rodents that, through variation in expression levels, contribute to the predisposition to consume varying amounts of alcohol. One such candidate gene is Gnb1 (the G protein beta 1 subunit, Gpi). Brain levels of the Gpi protein are inversely correlated with levels of alcohol consumption in inbred and recombinant inbred strains of mice and in lines of mice selected for differences in alcohol consumption. Treatment of mice with a lentiviral vector expressing a shRNA targeting Gnb1 lowered Gpi levels in nucleus accumbens and increased alcohol consumption by DBA/2 mice. Gpi, as a dimer with Gy proteins, affects numerous intracellular signaling pathways, and has also been reported to interact with, and modify the transcriptional activity of, the Class lla histone deacetylases (HDACs) 4 and 5. HDACs generally repress transcription via modification of histone proteins and class lla HDACs can shuttle between nucleus and cytoplasm, which can regulate their transcriptional activity. In particular, the direct Gpy-HDAC interaction reduces HDAC activity, and therefore has the potential to regulate the transcription of other genes. Given that HDACS activity has previously been found to be crucial for the rewarding effect of cocaine, and that HDAC inhibition reduces alcohol consumption, a role for the Gpy-HDAC interaction in alcohol consumption is postulated. Alcohol consumption will be measured after lowering Gnb1 expression in brains of low alcohol-consuming mice, and after inhibiting or lowering expression of HDACs in brain of high alcohol-consuming mice. To assess the link between Gpi and HDACs, HDAC transcriptional activity (transcript levels and promoter acetylation), as well as HDAC subcellular localization, will be determined after lowering Gpi with RNAi. Overall, this project will investigate molecular mechanisms, focusing on chromatin modification, by which a previously identified candidate gene for alcohol consumption/preference influences transcriptional networks that may underlie this phenotype.