中文摘要：

基因组中存在大量重复序列,这些重复序列究竟具有何种生物学功能以及通过何种方式发挥功能目前仍然是一个未解之谜.许多重复序列来源于转座元件在基因组中的整合,long interspersed elements（LINE-1,L1）逆转座子是哺乳动物基因组中非常重要的一类转座元件,由其来源的DNA序列占基因组的17%,并且L1可能通过多种方式影响基因组.虽然目前基因组中仍然有少数L1保留转座能力,大部分L1由于积累了大量的突变而失去了转座能力.正常组织中L1究竟呈现怎样的表达状况,是否发挥不依赖转座作用的功能,目前尚缺乏最基本的了解.通过采用高通量测序方法,我们在转录组水平研究了大鼠不同发育期大脑皮质中一类不具备转座活性的全长非完整L1（FLn I-L1）的表达模式,分析了FLnI-L1的表达与邻近基因的关系.同时,通过全基因组水平分析与FLn I-L1表达趋势一致的基因,我们推测FLnI-L1可能参与调控与神经发育有关的信号通路.本研究揭示了大鼠大脑皮质发育过程中FLn I-L1的表达模式,为进一步研究L1的生物学功能奠定了基础.

英文摘要：

The mammalian genome contains a large amount of repeat sequence derived from transposable elements. Whether these repeat sequences play roles in normal developmental and physiological processes remains unclear. As a major component of genomic repeat sequences, long interspersed elements（LINE-1 or L1） have long been regarded as important retrotransposon in mammalian genomes. Although most L1 have lost the retrotransposon activity, active L1 retrotransposons exist in mammalian genomes and L1 may impact the genome in a variety of ways. However, the expression profiles of L1 in normal tissues have not been reported; therefore, whether L1 play retrotransposition-independent functions in normal tissues is unknown. In the present study, global profiling of the L1 m RNA transcriptome of developing rat cerebral cortex was carried out using next-generation sequencing. We observed interesting developmentally-regulated expression of a group of full-length non-intact L1s（FLnI-L1）. The relationship between the expression of an L1 and its neighboring genes was also analyzed. A genome-wide analysis of genes whose expressions were correlated closely with FLn I-L1 expression suggested that FLn I-L1 may be involved in pathways related to the regulation of brain development. The dataset described here provides the first comprehensive analysis of a FLn I-L1 expression profile in developing cerebral cortex and will contribute to future understanding of the functions of L1 in brain development.