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Hypomethylation and ADA gene expression in mouse CAK cells
R L Stallings1, M J Siciliano, M L Frazier
1Department of Genetics, University of Texas System Cancer Center, M.D. Anderson Hospital and Tumor Institute, Texas Medical Center, Houston 77054.
Somatic Cell and Molecular Genetics
|January 1, 1989
Summary
Adenosine deaminase (ADA) gene regulation involves complex mechanisms. Methylation controls ADA gene transcription, offering a model for studying gene regulation elements.
Area of Science:
- Molecular Biology
- Gene Regulation
- Epigenetics
Background:
- Adenosine deaminase (ADA) enzyme activity exhibits significant variation across tissues and developmental stages, indicating complex transcriptional control.
- Previous studies suggested a trans-acting factor regulates the ADA locus, demonstrated by trans-activation in hybrid cell nuclei.
Purpose of the Study:
- To investigate the gene regulation of adenosine deaminase (ADA) in the mouse embryo fibroblast cell line, CAK, which lacks detectable ADA enzyme activity.
- To explore the role of DNA methylation in the transcriptional control of the ADA gene.
Main Methods:
- Somatic cell fusion experiments were conducted to assess ADA activation in CAK cells.
- CAK cells were treated with 5-azacytidine and Xyl-A selection to induce ADA expression.
- Molecular analysis, including methylation analysis of the ADA gene's 5' and 3' regions, was performed on parental and derivative cell lines.
Main Results:
- The CAK cell line, despite being near euploid, showed altered gene regulation leading to undetectable ADA enzyme activity.
- Somatic cell fusion did not activate ADA in CAK cells.
- Treatment with 5-azacytidine and Xyl-A selection yielded stable ADA-expressing CAK clones.
- Molecular analysis revealed hypomethylation in both 5' and 3' regions of the ADA gene in the ADA-positive clones compared to parental cells.
Conclusions:
- DNA methylation is identified as a critical element in the transcriptional control of the adenosine deaminase (ADA) gene.
- The ADA gene serves as a valuable model for investigating the interplay between cis- and trans-acting regulatory elements in gene expression.