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

神经功能需要准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，它通过在不改变潜在基因的情况下调节基因表达 DNA序列。DNA甲基化是一种主要的表观遗传机制，其中甲基是共价的 连接到胞嘧啶的C5位，主要位于5‘-CpG-3’二核苷酸位点。尽管仍有少数人在 数字，越来越多的证据表明DNA甲基化可能在药物中发挥重要作用 上瘾。然而，为了坚定地确定DNA甲基化在药物成瘾中的作用，是否和 DNA甲基化是如何在神经元中发生变化和发挥作用的，必须加以解决。这是特别的 对于那些明确的、选择性地参与药物成瘾的神经元亚型来说，这是真的。为了解决这个问题， 我们在此建议研究甲基胞嘧啶双加氧酶TET1，这是一种新发现的DNA去甲基化 酶及其介导的DNA甲基化在两种主要神经元类型(D_1和D_2)中的转换 可卡因成瘾时伏核内的棘神经元(MSN)。在过去，我们发现了TET1，但是 而不是TET2或TET3(双加氧酶家族的另外两个成员)，是受可卡因选择性调节的 伏隔核。我们还证明了TET1介导药物奖赏行为。在这里，我们建议 Tet1在D1MSN和D2MSN中具有不同的功能，它们在成瘾奖赏中通常扮演相反的角色 电路。我们还将阐明TET1介导的神经元亚型特异性DNA甲基化在D1- 和D2-MSN。最后，我们将探讨DNA的因果功能作用这一长期存在的问题 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 修饰选择性基因座DNA甲基化的方法。完成后，我们的研究不仅将推进我们的 一种神经元亚型特异性药物成瘾的DNA表观遗传学基础的科学认识 它还将提供一条途径，通过细胞类型- 特定的精确的表观基因组编辑，这在未来的治疗应用中具有明显的潜在用途。

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.