Enhancers for RNA polymerase I in mouse ribosomal DNA.

作者：Craig S. Pikaard, Louise K. Pape, Sheryl L. Henderson, Kenneth Jospeh Ryan, Mark H. Paalman, Margaret A. Lopata, R H Reeder, Barbara Sollner-Webb · 发表于：Molecular and Cellular Biology · 年份：1990 · DOI：10.1128/mcb.10.9.4816 · 被引用次数：92 · 研究领域：Genomics and Chromatin Dynamics、RNA Research and Splicing、RNA modifications and cancer

The intergenic spacer of the mouse ribosomal genes contains repetitive 140-base-pair (bp) elements which we show are enhancers for RNA polymerase I transcription analogous to the 60/81-bp repetitive enhancers (enhancers containing a 60-bp and an 81-bp element) previously characterized from Xenopus laevis. In rodent cell transfection assays, the 140-bp repeats stimulated an adjacent mouse polymerase I promoter when located in cis and competed with it when located in trans. Remarkably, in frog oocyte injection assays, the 140-bp repeats enhanced a frog ribosomal gene promoter as strongly as did the homologous 60/81-bp repeats. Mouse 140-bp repeats also competed against frog promoters in trans. The 140-bp repeats bound UBF, a DNA-binding protein we have purified from mouse extracts that is the mouse homolog of polymerase I transcription factors previously isolated from frogs and humans. The DNA-binding properties of UBF are conserved from the mouse to the frog. The same regulatory elements (terminators, gene and spacer promoters, and enhancers) have now been identified in both a mammalian and an amphibian spacer, and they are found in the same relative order. Therefore, this arrangement of elements probably is widespread in nature and has important functional consequences.