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Bovine leukemia virus long terminal repeat: a cell type-specific promoter
Science (New York, N.Y.)
|January 18, 1985
Summary
The bovine leukemia virus (BLV) long terminal repeat (LTR) promoter shows cell-type-specific activity, functioning only in producer cells. Sequences both upstream and downstream of the RNA start site are crucial for its gene expression regulation.
Area of Science:
- Virology
- Molecular Biology
- Gene Regulation
Background:
- Bovine leukemia virus (BLV) is an oncogenic retrovirus.
- The long terminal repeat (LTR) contains regulatory elements controlling viral gene expression.
- Understanding BLV LTR function is key to deciphering viral pathogenesis.
Purpose of the Study:
- To investigate the functional activity of the BLV LTR promoter.
- To identify regulatory sequences within the BLV LTR that influence gene expression.
- To determine the cell-type specificity of the BLV LTR.
Main Methods:
- Transfection of various cell lines with recombinant plasmids containing the BLV LTR linked to the chloramphenicol acetyltransferase (CAT) gene.
- Monitoring transient expression of CAT activity as a measure of LTR promoter function.
- Site-directed mutagenesis to delete specific regions within the BLV LTR.
Main Results:
- BLV LTR-driven CAT expression was observed exclusively in established BLV-producer cell lines (FLK and bat lung cells).
- Deletion of sequences 100-170 nucleotides upstream of the RNA start site reduced CAT activity by approximately tenfold.
- Removal of sequences from 50 base pairs downstream to the 3'-end of the LTR decreased CAT activity by 87%.
Conclusions:
- The BLV LTR exhibits unusual cell type-specific promoter activity.
- Both 5' and 3' regions relative to the RNA start site are critical for BLV LTR-mediated gene expression.
- These findings highlight the complex regulatory mechanisms of the BLV LTR.