Opposing roles of miR-495 and HuD in addiction-related plasticity and behavior

 描述（由申请人提供）：物质使用障碍（SUD）的特征是无症状期后的慢性复发。这一特征被假设源于药物诱导的成瘾相关基因（ARG）表达改变引起的皮质边缘回路功能和结构的持续改变。ARG和成瘾样行为的转录和表观遗传调控已经得到很好的表征，但转录后调控的作用是一个研究不足，但有前途的领域。转录后调节的一种机制，mRNA稳定性，可以通过因子与3 'UTR内的离散识别位点的直接结合来影响。RNA结合蛋白（RBP）是mRNA稳定性的调节因子之一。HuD是一种神经元特异性RBP，其稳定mRNA并受神经元活性和可卡因调节。另一种类型的转录后调节因子，微小RNA（miRNA），是靶向特定mRNA以降解或翻译抑制的非编码RNA。由于RBP和miRNA都靶向3 'UTR，这就打开了这两类分子竞争进入特定识别位点的可能性。我们已经发现，一个特定的miRNA，miR-495，和HuD通过结合到相同的GUUUGUUUG序列靶向一组共享的mRNA。许多这些共同的目标，包括BDNF和Camk 2a，都与成瘾有关，被认为是ARG。miR-495和HuD的慢病毒（LV）过表达（OE）分别导致伏隔核壳（NAcSh）内靶mRNA表达减少或增加，这是一个与成瘾相关行为相关的区域。在一项初步的条件性位置偏好（CPP）研究中，我们发现可卡因偏好似乎与较低的NAc miR-495表达有关。此外，发现HuD OE小鼠系显示与野生型同窝仔相比CPP增加。由于miR-495/HuD及其靶点是树突状定位的，因此我们对miR-495和HuD在结构可塑性中可能发挥的作用感兴趣。使用扩散亲脂性染料方法（DiOListics），我们发现幼稚HuD OE在NAcSh内的棘形态中具有明显的结构改变。相比之下，LV介导的miR-495 OE似乎完全破坏了棘的形成或成熟。结合起来，这导致了我的假设，可卡因差异调节HuD和miR-495，导致ARG表达，药物诱发的结构可塑性和成瘾样行为的相反变化，分别促进或抑制这些。这项提议试图用三个具体目标来检验他的假设：1）可卡因CPP是否差异调节NAc内的HuD、miR-495和树突棘结构？2)NAC miR-495和HuD是否导致树突棘形态学的相反变化？3)miR-495和HuD在可卡因CPP中具有相反的作用吗？了解共同靶点的转录后竞争对细胞动力学和行为的作用可能会为新的药理学治疗提供信息，这些治疗有助于缓解这种转录后竞争。

 DESCRIPTION (provided by applicant): Substance use Disorders (SUDs) are characterized by chronic relapse after periods without symptoms. This feature has been hypothesized to stem from persistent alterations in corticolimbic circuit function and structure caused by drug-induced alterations in addiction-related gene (ARG) expression. Transcriptional and epigenetic regulation of ARGs and addiction like behaviors have been well characterized but the role of post- transcriptional regulation is an understudied, yet promising field. One mechanism of post-transcriptional regulation, mRNA stability, can be influenced by direct binding of factors to discrete recognition sites within the 3'UTR. RNA binding proteins (RBPs) are one regulator of mRNA stability. HuD is a neuronal specific RBP that stabilizes mRNAs and is regulated by neuronal activity and cocaine. Another type of post-transcriptional regulator, microRNAs (miRNAs), are non-coding RNAs that target specific mRNAs for degradation or translational repression. Since both RBPs and miRNAs target the 3'UTR, this opens the possibility that these two classes of molecules could compete for access to a specific recognition site. We have found that a specific miRNA, miR-495, and HuD target a set of shared mRNAs via binding to the same GUUUGUUUG sequence. Many of these shared targets, including Bdnf and Camk2a have been implicated in addiction and are considered ARGs. Lentiviral (LV) overexpression (OE) of miR-495 and HuD caused decreased or increased expression, respectively, of target mRNAs within the Nucleus Accumbens Shell (NAcSh), a region associated with addiction-related behaviors. In a preliminary conditioned place preference (CPP) study, we found that cocaine preference appears to be related to lower NAc miR-495 expression. Additionally, a HuD OE mouse line was found to show increased CPP compared to wild type littermates. Since miR-495/HuD and their targets are dendritically localized, we were interested in the role that miR-495 and HuD may play in structural plasticity. Using a diffuse lipophilic dye method (DiOListics), we found that naïve HuD OE had distinct structural alterations in spine morphology within the NAcSh. In contrast, LV mediated OE of miR-495 seems to disrupt spine formation or maturation entirely. Combined, this led to my hypothesis that cocaine differentially regulates HuD and miR-495 leading to opposite changes in ARG expression, drug-evoked structural plasticity, and addiction-like behaviors, either facilitating or inhibiting these, respectively. This proposal seeks to test his hypothesis with three specific aims 1) Are HuD, miR-495, and dendritic spine structure within the NAc differentially regulated by cocaine CPP? 2) Do NAC miR-495 and HuD cause opposite changes in dendritic spine morphology? 3) Do miR-495 and HuD have opposite roles in cocaine CPP? Understanding the role of post-transcriptional competition of shared targets on cellular dynamics and behavior may inform new pharmacological treatments that tip this post-transcriptional competition in the favor of remission.