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Synthesis and processing of small B2 transcripts in mouse embryonal carcinoma cells.
T S Bladon1, C J Frégeau, M W McBurney
1Department of Medicine, University of Ottawa, Ontario, Canada.
Molecular and Cellular Biology
|August 1, 1990
Summary
B2 RNA, transcribed by RNA polymerase III, is abundant in embryonic cells but scarce in differentiated cells. Its expression is transcriptionally regulated during cell differentiation.
Area of Science:
- Molecular Biology
- Gene Expression Regulation
- RNA Metabolism
Background:
- B2 genes are short, repetitive sequences transcribed by RNA polymerase III.
- B2 RNA transcripts are abundant in embryonic and transformed cells but absent in normal differentiated cells.
Purpose of the Study:
- To investigate the regulation of B2 RNA levels during retinoic acid-induced differentiation of P19 embryonal carcinoma cells.
- To characterize the different B2 RNA species and their stability.
- To propose a model for B2 RNA metabolism.
Main Methods:
- Analysis of B2 RNA levels during P19 cell differentiation.
- RNA stability assays.
- Characterization of B2 RNA lengths and polyadenylation.
- Isolation and transcription of B2 cDNA in human cells.
Main Results:
- B2 RNA levels transiently increase early in differentiation, followed by a rapid decrease.
- Changes in B2 RNA levels are primarily due to transcriptional modulation, as RNA stability is unaffected.
- Four short-lived B2 RNAs (150, 180, 240, 500 nucleotides) were identified.
- Larger B2 RNAs are polyadenylated and more stable.
- Isolated B2 cDNA is highly conserved and transcribes distinct transcripts in human cells.
Conclusions:
- B2 RNA expression is tightly regulated transcriptionally during cellular differentiation.
- A model for B2 RNA metabolism involving transcription, post-transcriptional modification, and nucleocytoplasmic transport is proposed.