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Protein binding regions in the mouse and rat protamine-2 genes
P A Johnson1, D Bunick, N B Hecht
1Department of Biology, Tufts University, Medford, Massachusetts 02155.
Biology of Reproduction
|January 1, 1991
Summary
This study identifies regulatory elements in the mouse protamine-2 gene promoter. Protein-DNA binding assays reveal factors that repress transcription in non-testis tissues and enhance it in adult testis.
Area of Science:
- Molecular Biology
- Gene Regulation
- Reproductive Biology
Background:
- Protamine genes are crucial for sperm development, exhibiting tissue-specific and temporal expression.
- Understanding the regulatory mechanisms of protamine gene transcription is essential for defining sperm chromatin packaging.
Purpose of the Study:
- To investigate the regulatory mechanisms governing tissue-specific and temporal transcription of the mouse protamine-2 gene.
- To identify specific 5' flanking regions of the mouse protamine-2 gene that bind regulatory proteins.
Main Methods:
- In vitro protein-DNA binding assays were performed using nuclear extracts from various mouse tissues (adult testis, 16-day-old testis, liver, brain).
- Analysis focused on identifying DNA-protein interactions within the 5' flanking regions of the mouse protamine-2 gene.
Main Results:
- A DNA fragment (-419 to -141) bound a repressor factor present in non-expressing tissues (liver, brain, immature testis), but not in adult testis.
- Another region (-140 to -23) bound ubiquitous factors and a testis-specific factor, suggesting positive regulation for high transcription levels.
- These binding patterns differed significantly from the rat protamine-2 gene, indicating species-specific regulation.
Conclusions:
- The 5' flanking region from -419 to -141 likely mediates negative regulation, preventing protamine-2 gene expression in inappropriate tissues.
- The region from -140 to -23 contains positive regulatory elements critical for high-level protamine-2 gene transcription in adult testis.
- These findings represent the first analysis of protein binding sites within the promoter of a testis-specific gene, providing insights into gene regulation during spermatogenesis.