Generation and initial charcterization of a mouse with floxed miR-155 for conditi

描述（由申请人提供）：遗传学的最新进展发现了一类新的RNA分子，称为microRNAs (miRNA)，参与基因调控。mirna是约22个核苷酸的单链RNA分子，与mrna的3'非翻译区（UTR）的一个位点互补。miRNA对mRNA的退火抑制蛋白质翻译，有时促进mRNA的切割。这种调控为DNA->mRNA->蛋白的经典“线性”概念增加了一层意想不到的复杂性。近年来的快速进展表明miRNA在调节神经元和免疫功能方面的重要性。在中枢神经系统中，mirna与突触发育和记忆形成有关。我们发现miR-155的组成性敲除（miR-155-/-）使小鼠大脑中动脉闭塞/再灌注（MCAO/R）模型中的梗死面积增加了约50%。然而，miR-155在中枢神经系统中至少通过星形胶质细胞和小胶质细胞表达。miR-155-/-的组成性敲除使得无法确定是哪种细胞类型导致了梗死面积的大幅增加。因此，我们希望使用Cre/loxP方法生成条件敲除模型。使用这种完善的方法，我们将能够将固定的miR-155 （miR-155fl/fl）与现成的用于星形胶质细胞和小胶质细胞的cre驱动小鼠交叉，以产生细胞特异性敲除小鼠。该项目的长期目标是产生miR-155的条件敲除，以研究细胞特异性miR-155在CNS损伤（如缺血性损伤）中的作用。我们相信，在随后的实验中使用该模型确定的分子机制可能为中枢神经系统损伤（如中风）的治疗干预确定新的途径。

DESCRIPTION (provided by applicant): Recent progress in genetics has identified a new class of RNA molecules called microRNAs (miRNA) involved in gene regulation. miRNAs are single-stranded RNA molecules of ~22 nucleotides complementary to a site in the 3' untranslated region (UTR) of mRNAs. The annealing of the miRNA to the mRNA inhibits protein translation and sometimes facilitates cleavage of the mRNA. This regulation adds an unexpected layer of complexity to the classic "linear" concept of DNA->mRNA->protein. Fast paced progress in the recent years showed the importance of miRNA in regulating neuronal and immune functions. In the CNS, miRNAs have been implicated in synaptic development and memory formation. We have found that constitutive knock out of miR-155 (miR-155-/-) increases the infract area in the mouse middle cerebral artery occlusion/reperfusion (MCAO/R) model by ~50%. However, miR-155 is expressed in the CNS in by at least astrocytes and microglia. The constitutive knock out of miR-155-/- makes it impossible to determine which cell type is responsible for the substantial increase in infarct area. We therefore wish to generate a conditional knock out model using the Cre/loxP approach. Using this well established approach we will be able to cross the floxed miR-155 (miR-155fl/fl) with readily available Cre-driver mice for astrocytes and microglia to generate cell specific knock out mice. The long-term goal of this project is to generate conditional knock outs of miR-155 to investigate the role of cell-specific miR-155 in CNS injury such as ischemic injury. We believe that the molecular mechanisms identified in subsequent experiments using this model may indentify new pathways for therapeutic intervention in CNS injuries such as stroke. PUBLIC HEALTH RELEVANCE: The broad, long-term goal of this project is to understand the role of miR-155 in the activation of astrocytes microglial cells. We believe that the signal transduction mechanisms identified through our experiments may constitute new targets for therapeutic intervention in CNS injuries associated with glial activation such as trauma, multiple sclerosis or stroke.