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Human integrin beta3 gene expression: evidence for a megakaryocytic cell-specific cis-acting element
1Division of Hematology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Blood
|October 9, 1998
Summary
Researchers mapped regulatory DNA elements controlling human integrin beta3 gene expression. They identified a key sequence (GAGGGG) crucial for megakaryocytic cell activity, suggesting Sp1 transcription factor involvement.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Integrin beta3 is vital for cell adhesion and expressed in specific tissues.
- Regulatory mechanisms controlling integrin beta3 gene expression remain largely unknown.
Purpose of the Study:
- To identify cis-acting DNA elements and trans-acting factors regulating human integrin beta3 gene expression.
- To map the 5' regulatory region of the integrin beta3 gene.
Main Methods:
- Analysis of upstream regulatory regions using reporter gene assays in various cell lines.
- Electrophoretic mobility shift assays (EMSA) to study nuclear protein binding.
- Mutational analysis to pinpoint critical cis-acting elements.
Main Results:
- Identified positive and negative regulatory regions in the integrin beta3 5' flanking sequence.
- A region from -115 to +29 demonstrated cell-specific activity, with a GAGGGG sequence (-113 to -108) critical for megakaryocytic cell lines.
- Evidence suggests the Sp1 transcription factor binds to a CCCACCC sequence (-70) and influences beta3 expression.
Conclusions:
- Detailed map of integrin beta3 transcriptional regulatory elements established.
- Discovered potent megakaryocyte-preferential regulatory sequences.
- Sp1 transcription factor likely augments integrin beta3 gene expression.