植物非生物胁迫诱导启动子顺式元件及转录因子研究进展

顺式作用元件(cix-acting element)是与结构基因串联的特定DNA序列,是转录因子的结合位点,它们通过与转录因子结合调控基因转录的精确起始和转录效率,在植物基因表达调控过程中起着重要的作用.非生物胁迫诱导基因的表达受其上游启动子顺式作用元件及转录因子的调控,目前已发现了多种与非生物胁迫相关的顺势作用元件及转录因子,如DRE元件及DREB类转录因子、MYB元件及MYB类转录因子、GT-1元件及GT-1类转录因子等.顺式作用元件及转录因子的研究对研究植物非生物胁迫相关基因的表达调控具有重要意义,综述植物非生物胁迫诱导启动子功能元件及转录因子的研究进展.     

The splicing factor SF2/ASF binds to ARS homologs in a human rDNA replication origin

The function of the relatively well-studied DNA replication origins in the yeast Saccharomyces cerevisiae is dependent upon interactions between origin replication complex (ORC) proteins and several defined origin sequence elements, including the 11 bp ARS consensus sequence (ACS). Although the ORC proteins, as well as numerous other protein components required for DNA replication initiation, are largely conserved between yeast and mammals, DNA sequences within mammalian replication origins are highly variable and sequences homologous to the yeast ACS elements are generally not present. We have previously identified several replication initiation sites within the nontranscribed spacer region of the human ribosomal RNA gene, and found that two highly utilized sites each contain a homologue of the yeast ACS embedded within a DNA unwinding element and a matrix attachment region. Here we examine protein binding within these initiation sites, and demonstrate that these ACS homologues specifically bind the alternate splicing factor SF2/ASF as well as GAPDH in vitro, and present evidence that the SF2/ASF interaction also occurs within the nuclei of intact cells. As the moderate upregulation of SF2/ASF has been linked to oncogenesis through the promotion of alternatively spliced forms of several regulatory proteins, our results suggest an additional mechanism by which SF2/ASF may influence the transformed cell phenotype.