Neuron subtype specific role of DNA methylcytosine dioxygenase TET1 in cocaine addiction

神经功能需要精确控制基因转录以响应环境刺激。 表观遗传学在这一过程中起着至关重要的作用，它通过调节基因表达而不改变潜在的基因表达。 DNA序列DNA甲基化是一种主要的表观遗传机制，其中甲基基团共价连接到DNA上。 偶联到胞嘧啶的C5位置，主要在5 '-CpG-3'二核苷酸位点。尽管仍有少数人 越来越多的证据表明，DNA甲基化可能在药物代谢中发挥重要作用。 成瘾然而，要确定DNA甲基化在药物成瘾中的作用， DNA甲基化的变化是如何发生的，以及在神经元中的功能必须得到解决。这是特别 对于那些确定的神经元亚型选择性地参与药物成瘾是正确的。为了解决这个问题， 我们在此提出研究甲基胞嘧啶双加氧酶TET 1，一种新发现的DNA去甲基化酶， 酶及其介导的两种主要神经元类型（D1-和D2-培养基）中的DNA甲基化周转 多刺神经元（MSNs）。在过去，我们已经发现了TET 1，但 而不是TET 2或TET 3（双加氧酶家族的另外两个成员），在 脑桥核我们还表明TET 1介导药物奖励行为。在这里，我们建议 TET 1在D1-和D2-MSN中具有不同的功能，它们在成瘾奖励中通常起相反的作用 电路我们还将阐明TET 1介导的D1-HT细胞中神经元亚型特异性DNA甲基化的变化。 D2-MSN最后，我们将探讨DNA的因果功能作用的长期问题 通过经证实的基于CRISPR-Cas9的表观基因组编辑在药物成瘾相关行为中的甲基化 在选择性位点修饰DNA甲基化的方法。完成后，我们的研究不仅将促进我们的 对神经元亚型特异性药物成瘾的DNA表观遗传基础的科学理解 以这种方式，它还将提供一种途径，通过细胞类型来操纵与药物成瘾相关的行为， 特异性的精确表观基因组编辑，其对于未来的治疗应用具有明显的潜在效用。

Neural function requires accurate control of gene transcription in response to environmental stimuli. Epigenetics plays a crucial role in this process by modulating gene expression without changing underlying DNA sequences. DNA methylation is a major epigenetic mechanism, wherein a methyl group is covalently coupled to the C5 position of cytosine, predominantly at 5'-CpG-3' dinucleotide sites. Though still few in number, accumulating evidence demonstrates that DNA methylation may play important roles in drug addiction. However, to firmly establish DNA methylation's role in drug addiction, the question of whether and how DNA methylation changes take place and function in neurons must be addressed. This is particularly true for those defined neuronal subtypes selectively engaged in drug addiction. To address this question, we herein propose to study methylcytosine dioxygenase TET1, a newly identified DNA demethylation enzyme, and its mediated DNA methylation turnover in the two major neuron types (D1- and D2- medium spiny neurons (MSNs)) in nucleus accumbens in cocaine addiction. In the past, we have found TET1, but not TET2 or TET3 (the other two members of the dioxygenase family), is selectively regulated by cocaine in the nucleus accumbens. We have also shown TET1 mediates drug reward behaviors. Here, we propose TET1 carries distinct functions in D1- and D2-MSNs, which usually play opposite roles in addiction reward circuitry. We will also elucidate TET1-mediated neuron subtype-specific DNA methylation changes in D1- and D2-MSNs. Lastly, we will probe the long-standing question of the causal functional role of DNA methylation in drug addiction-relevant behavior through a proven CRISPR-Cas9 based epigenome editing approach to modify DNA methylation at selective loci. Upon completion, our study will not only advance our scientific understanding of DNA epigenetic underpinnings of drug addiction in a neuron subtype-specific manner, it will also provide a path to manipulate behaviors associated with drug addiction through cell type- specific precision epigenome editing, which has obvious potential utility for future therapeutic applications.