PiRNAs and ischemic brain damage

描述(申请人提供)：编码蛋白质的基因占真核基因组的2%，因为~98%的转录输出是非编码(NC)RNA。NcRNAs目前被认为是转录和翻译的主控制者，因此它们功能的任何破坏都可能导致严重的细胞内稳态的破坏。尽管它们的丰富性和最重要的功能重要性，到目前为止，很少有研究评估ncRNAs在急性脑损伤中的意义。我们和其他人最近发现，miRNA的表达谱在中风后会发生广泛的变化；调节特定的miRNAs可以诱导神经保护。这些研究表明ncRNAs在缺血病理生理中的作用，但其他ncRNAs如piwi相互作用RNA(PiRNA)在缺血性脑损伤中的意义尚未得到评估。到目前为止，在真核生物中发现了40,000个piRNAs，其中piRNAs(26到31个核苷酸)是所有ncRNAs中含量最丰富的。它们的主要功能是选择性地靶向和沉默由反转录转座子(RT)形成的RNA。由于RTS是转座子(跳跃基因)的主要类别，它突变和破坏蛋白质编码基因，piRNAs平衡基因组的适合性以维持细胞平衡。我们假设“局灶性脑缺血改变了对缺血性脑损伤具有功能意义的脑内piRNAome”。在初步研究中，我们观察到被评估的40,000个piRNAs中有10%在大鼠大脑皮层表达。此外，当大鼠遭受局灶性缺血时，106个皮质piRNAs要么上调要么下调(&gt；2.5倍)。生物信息学表明，卒中反应的piRNAs有几个RT靶标，分布在整个基因组中，这些piRNAs的启动子包含多种转录因子的结合位点。目的1a研究短暂性局灶性脑缺血后piRNA表达谱的时间模式。目的1b是进行生物信息学分析，寻找缺血后改变的piRNAs靶向的RTS。目的1c是进行生物信息学分析，以确定卒中反应piRNAs启动子中的转录因子结合位点。目的2检测敲除特定的piRNAs对局灶性脑缺血后组织学和行为学结果的影响。AIM 1的结果将生成实验性卒中后piRNA图谱的目录，并将确定可能的卒中反应piRNA的下游靶点和上游控制器。目的2的研究结果将显示piRNAs是否对卒中预后具有功能意义。 公共卫生相关性： 中风是成年人死亡和致残的主要原因。导致中风引起的脑损伤的机制还没有完全了解。这项提议希望评估中风引起的脑损伤是否部分由一种称为piRNAs的非编码RNA亚型介导。

DESCRIPTION (provided by applicant): The protein-coding genes represent <2% of the eukaryotic genome as ~98% of the transcriptional output is non-coding (nc) RNAs. The ncRNAs are currently considered as the master controllers of the transcription and translation and hence any disruption in their function could lead to severe compromises in cellular homeostasis. Despite their abundance and paramount functional importance, very few studies to date evaluated the significance of ncRNAs in acute brain damage. We and others recently showed that miRNA expression profiles alter extensively following stroke; and modulating specific miRNAs induce neuroprotection. These studies indicate the role of ncRNAs in ischemic pathophysiology, but the significance of other ncRNAs like piwi-interacting RNA (piRNA) to ischemic brain damage is not evaluated yet. The piRNAs (26 to 31 nt long) are the most abundant of all ncRNAs with >40,000 piRNAs identified so far in eukaryotes. The major function attributed to them is to selectively target and silence the RNAs formed by the retrotransposons (RTs). As RTs are the predominant class of transposons (jumping genes) which mutate and disrupt the protein-coding genes, the piRNAs balance the fitness of the genome to maintain the cellular equilibrium. We hypothesize that "Focal ischemia alters cerebral piRNAome with functional significance to ischemic brain damage". In preliminary studies, we observed that >10% of the 40,000 piRNAs evaluated are expressed in rat cerebral cortex. Furthermore, when rats were subjected to focal ischemia, 106 cortical piRNAs were either up- or down-regulated (>2.5 fold). Bioinformatics showed that stroke- responsive piRNAs have several RT targets distributed throughout the genome, and the promoters of those piRNAs contain binding sites for multiple transcription factors. Aim 1a is to study the temporal pattern of piRNA expression profiles following transient focal ischemia. Aim 1b is to conduct bioinformatics analysis to find RTs targeted by piRNAs altered after ischemia. Aim 1c is to conduct bioinformatics analysis to identify transcription factor binding sites in the promoters of the stroke-responsive piRNAs. Aim 2 is to test the effect of knocking-down specific piRNAs on the histological and behavioral outcomes after focal ischemia. Aim 1 results will generate a catalog of the piRNA profiles after experimental stroke, and will identify the putative down-stream targets and upstream controllers of stroke-responsive piRNAs. Aim 2 results will show if piRNAs have a functional significance to stroke outcome. PUBLIC HEALTH RELEVANCE: Stroke is a leading cause of death and disability in adult population. The mechanisms that lead to stroke-induced brain damage are not fully understood. This proposal wishes to evaluate if stroke-induced brain damage is mediated in part by a subtype of non- coding RNAs known as piRNAs.