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Enhancers for RNA polymerase I in mouse ribosomal DNA
C S Pikaard1, L K Pape, S L Henderson
1Basic Sciences Division, Hutchinson Cancer Research Center, Seattle, Washington 98104.
Molecular and Cellular Biology
|September 1, 1990
Summary
Mouse ribosomal DNA contains repetitive elements that enhance RNA polymerase I transcription. These elements function similarly in mice and frogs, suggesting a conserved mechanism for ribosomal gene regulation across species.
Area of Science:
- Molecular Biology
- Genetics
- Developmental Biology
Background:
- Ribosomal genes are crucial for cell function and are regulated by specific DNA elements.
- Repetitive elements in the intergenic spacer of mouse ribosomal genes were previously identified.
Purpose of the Study:
- To characterize the function of 140-base-pair (bp) repetitive elements in the mouse ribosomal gene intergenic spacer.
- To compare the function of mouse enhancers with previously characterized Xenopus laevis enhancers.
- To investigate the DNA-binding properties of proteins interacting with these repetitive elements.
Main Methods:
- Rodent cell transfection assays to assess enhancer activity in cis and trans.
- Frog oocyte injection assays to evaluate enhancer function across species.
- Purification of a DNA-binding protein (UBF) from mouse extracts and characterization of its binding properties.
Main Results:
- Mouse 140-bp repeats function as enhancers for RNA polymerase I transcription in rodent cells.
- These mouse repeats enhance homologous frog ribosomal gene promoters and compete with frog promoters, indicating cross-species functionality.
- The DNA-binding protein UBF, conserved between mice and frogs, binds to these repetitive elements.
Conclusions:
- Repetitive elements in the mouse ribosomal gene spacer act as enhancers for RNA polymerase I transcription.
- The functional properties and DNA-binding protein interactions of these enhancers are conserved between mammals and amphibians.
- The identified regulatory elements and their arrangement in the ribosomal DNA spacer are likely widespread and functionally significant across vertebrates.