Transgenic rat overexpressing miR-21 in vascular smooth muscle cells:functional i

描述（由申请人提供）：MicroRNAs （miRNAs）是一类新的非编码小rna，通过降解mRNA或抑制蛋白质翻译负性调节基因表达。mirna已被证明在多种疾病中发挥着非常重要的作用，如癌症、病毒感染、遗传疾病和心血管疾病。最近我们发现，在多种癌症中异常过表达的致癌miRNA基因miR-21，在小鼠心脏肥大模型和大鼠颈动脉球囊损伤模型中也出现了上调。miR-21通过靶向磷酸酶和紧张素同源基因（PTEN）的3'非翻译区（UTR）敲低诱导血管平滑肌细胞和大鼠颈动脉球囊损伤模型的凋亡，并间接调节血管平滑肌细胞（VSMCs）中Bcl-2基因的表达。为了进一步了解miR-21调控血管疾病重要信号通路基因表达的分子机制，我们构建了由大鼠平滑肌细胞特异性启动子（rSM22）驱动miR-21基因的慢病毒载体，并构建了miR-21在VSMCs中过表达的转基因大鼠模型。我们发现，几种转基因大鼠始祖表现出一致的表型：生长迟缓和后肢轻微瘫痪。这一转基因大鼠模型必将为理解miRNA在心血管疾病中的功能提供新的思路，并有助于我们进一步评估miRNA在心血管疾病诊断和测试miRNA治疗方面的潜在应用。

DESCRIPTION (provided by applicant): MicroRNAs (miRNAs) are a new class of non-coding small RNAs that negatively regulate gene expression by either degrading mRNA or inhibiting protein translation. miRNAs have been shown to play very important roles in a variety of diseases, such as cancers, viral infection, genetic disorders, and cardiovascular diseases. Recently we found that miR-21, an oncogenic miRNA gene was aberrantly overexpressed in a variety of cancers, was also upregulated in the mouse cardiac hypertrophy model and rat carotid artery balloon injury model. Knockdown of miR-21 induced apoptosis in vascular smooth muscle cells and in the rat carotid artery balloon-injured model by targeting the 3'untranslated region (UTR) of the phosphatase and tensin homolog (PTEN) gene and indirectly regulated Bcl-2 gene expression in vascular smooth muscle cells (VSMCs). To further understand the molecular mechanism by which miR-21 regulates gene expression on the important signaling pathways, which play pivotal roles in vascular diseases, we constructed a lentiviral vector in which the miR-21 gene was driven by the rat smooth muscle cell specific promoter (rSM22) and generated a transgenic rat model in which miR-21 is overexpressed in VSMCs. We found that several transgenic rat founders display consistent phenotypes: growth retardation and slightly paralyzed hind limbs. This transgenic rat model will certainly provide insight to understanding miRNA functions in cardiovascular diseases and will help us further evaluate potential applications of miRNA in diagnosing and test miRNA based therapy for cardiovascular diseases. PUBLIC HEALTH RELEVANCE: This proposal is to characterize transgenic rats expressing miR-21 using lentiviral vector to address the biological functions of miRNAs by targeting miR-21 gene into vascular smooth muscle cells. The phenotype and molecular mechanisms underlying the phenotypes will also be examined using this transgenic rat models by investigating how miR-21 is involved in the posttranscriptional regulation.