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Tissue-specific regulation of the WT1 locus
J A Hewitt1, P M Kessler, C E Campbell
1Department of Cancer Biology, Cleveland Clinic Foundation, Ohio 44195, USA.
Medical and Pediatric Oncology
|November 1, 1996
Summary
The Wilms' tumor 1 (WT1) gene and its related WIT-1 transcript are crucial for urogenital development. A large 42 kb DNA region, not smaller fragments, correctly regulates WT1 gene expression in embryonic development.
Area of Science:
- Developmental Biology
- Genetics
- Molecular Biology
Background:
- The 11p13 Wilms' tumor locus contains two key genes, WT1 and WIT-1, vital for urogenital system development.
- Both genes exhibit specific spatial and temporal expression patterns during embryonic development, particularly in the kidneys and gonads.
- WT1 protein is essential for kidney development, but its precise function and that of WIT-1 remain under investigation, with WIT-1 potentially acting as an antisense regulator of WT1.
Purpose of the Study:
- To investigate the regulatory elements controlling the spatial and temporal expression of the WT1 gene.
- To understand the mechanisms governing WT1 and WIT-1 gene expression in urogenital development.
- To identify DNA sequences responsible for directing appropriate WT1 gene transcription during embryogenesis.
Main Methods:
- Analysis of chimeric reporter constructs with varying lengths of the WT1 5' region in cell lines and transgenic embryos.
- Comparative assessment of gene expression using different DNA constructs in mouse embryos at day 13.5.
- Utilizing stable transfectants of mouse Leydig cells (TM3) and transgenic embryos to evaluate gene regulation.
Main Results:
- Smaller reporter constructs (0.6-2.5 kb) of the WT1 5' region failed to drive expression in 13.5-day mouse embryos.
- A larger cosmid (42 kb) encompassing the WT1 5' region successfully directed abundant mRNA expression from correct initiation sites in both cell lines and transgenic embryos.
- These findings indicate the presence of crucial regulatory elements within the larger DNA region.
Conclusions:
- The regulation of WT1 gene expression during embryonic development requires a substantial DNA region, likely containing enhancers or other regulatory elements.
- Understanding these regulatory elements is critical for elucidating the roles of WT1 and WIT-1 in urogenital development.
- Further studies are underway to precisely map the DNA elements responsible for this complex regulation.