反向长非编码RNA Bait调控Brn2转录和神经细胞成熟的机制研究

在胚胎干细胞中的研究表明，超过60%的长非编码RNA源自蛋白编码基因启动子区的反向转录本。新生RNA测序发现在干细胞分化过程中反向转录的lncRNA和其正向蛋白编码基因的表达存在相同的趋势，但反向lncRNA的作用及意义不明。在尝试重编程人成纤维细胞至神经元细胞的过程中，我们发现在人神经细胞转分化过程中存在两个核查蛋白（gatekeeper）：RNA结合蛋白PTB控制神经细胞转分化的起始，其神经细胞同源蛋白nPTB控制神经细胞的成熟。nPTB功能的实现则是通过一个反向长非编码RNA Bait，Bait可调控其正向蛋白编码基因Brn2的转录，进而调节神经细胞成熟。 因此研究反向lncRNA Bait调控正向蛋白编码基因Brn2转录的分子机制将有助于我们理解反向转录的lncRNA存在的普遍作用及意义，也将加深我们对神经细胞重编程的理解，为开发高效的重编程新方法和研究神经退行性疾病提供理论基础。

Previous studies in human and murine embryonic stem cells indicate that over 60% of long non-coding RNA(lncRNA) is originate from divergent transcripts at promoter region of active protein-coding genes. Nascent RNA sequencing by Gro-seq(global run-on sequencing) find that these divergent transcribed lncRNA/mRNA gene pairs show coordinate changes during endodermal differentiation of embryonic stem cells. The function and biological significance of these antisense direction transcribed lncRNA is still unclear. In the attempt to direct reprogramming human dermal fibroblasts into neuronal cells, we find that there are two gatekeepers in human cells: RNA binding protein PTB controls the neuronal induction, whereas its neuronal homolog nPTB determines neuronal maturation, which is further achieved by modulating an antisense long non-coding RNA Bait (Brn2 antisense intergenic transcripts). Bait controls the transcription of its sense partner Brn2 and the onset of neuronal maturation, but the molecular mechanism is elusive. In the proposal, we will choose Bait as a model to study how antisense lncRNA regulate sense transcription and what is the underling mechanism for such regulation. The study will uncover the general biological significance of antisense transcribed lncRNA and lay the foundation for neuronal reprogramming; finally, we hope to develop a more efficient way to directly convert human adult fibroblasts into functional neurons to study neurological diseases. .