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CD43 gene expression is mediated by a nuclear factor which binds pyrimidine-rich single-stranded DNA
O C Farokhzad1, J M Teodoridis, H Park
1Leukocyte Biology and Inflammation Program, Renal Unit, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
Nucleic Acids Research
|June 28, 2000
Summary
A novel DNA-binding protein, PyRo1, regulates CD43 and beta2 integrin gene expression in immune cells. Its activity varies by cell type, suggesting a role in cell-specific gene regulation.
Area of Science:
- Molecular Biology
- Immunology
- Genetics
Background:
- CD43 is a crucial leukocyte surface molecule involved in cell adhesion and signal transduction.
- Understanding the regulation of CD43 gene expression is vital for comprehending immune cell function.
Purpose of the Study:
- To identify and characterize regulatory elements and DNA-binding proteins involved in human CD43 gene promoter activity.
- To investigate the cell-specific functional roles of identified regulatory factors.
Main Methods:
- Nuclease S1 hypersensitivity assays to map regulatory regions in the CD43 promoter.
- Electrophoretic mobility shift assays (EMSAs) to identify nuclear factors binding to the hypersensitive site.
- Site-directed mutagenesis to assess the functional impact of specific DNA motifs.
- Reporter gene assays in various human cell lines (Jurkat, K562, U937, CEM) to measure promoter activity.
Main Results:
- A nuclease S1 hypersensitive site (+18 to +39) in the CD43 promoter was identified, capable of activating gene expression.
- Two nuclear factors, PyRo1 and PyRo2, were found to bind this site, with PyRo1 binding preferentially to single-stranded DNA.
- Mutation of the TCCCCT motif critical for PyRo1 binding reduced CD43 promoter activity in a cell-specific manner (e.g., Jurkat, K562).
- PyRo1 also binds to promoter regions of CD11a, CD11b, CD11c, and CD11d genes, affecting CD11c promoter activity similarly.
- PyRo1's preferential binding to single-stranded DNA suggests a role for DNA secondary structures in regulating CD43 and CD11 gene expression.
Conclusions:
- PyRo1 is a key regulator of CD43 and beta2 integrin subunit gene expression.
- PyRo1 exhibits cell-specific functional activity, influencing gene expression differently across various leukocyte subtypes.
- DNA secondary structure may play a significant role in the transcriptional regulation of these immune-related genes.