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Multiple cis-acting DNA regulatory elements mediate hepatic angiotensinogen gene expression.
1Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Boston.
Molecular Endocrinology (Baltimore, Md.)
|June 1, 1989
Summary
Researchers identified six DNA control elements regulating angiotensinogen gene expression in liver cells. These elements, including the versatile SOAP box element, interact with DNA-binding proteins, demonstrating coordinated gene regulation.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Angiotensinogen is a precursor to angiotensin II, a key hormone in blood pressure regulation.
- Understanding tissue-specific gene expression requires identifying cis-acting DNA control elements and trans-acting factors.
- The rat angiotensinogen gene serves as a model for studying gene regulation.
Purpose of the Study:
- To identify DNA control elements within the rat angiotensinogen gene.
- To analyze the cellular specificity and regulatory mechanisms of these elements.
Main Methods:
- Fusion genes with 5' or 3'-deleted angiotensinogen sequences linked to a luciferase reporter gene were created.
- These constructs were introduced into Hep G2 (expresses angiotensinogen) and JEG-3 (does not express) cells.
- DNase I protection assays and gel mobility shift assays were used to study protein interactions.
Main Results:
- Six transcriptionally active elements were identified within 688 base pairs of the 5'-flanking region.
- The SOAP box element (60-108 bp) acted as a silencer or enhancer depending on its position.
- Mutating the SOAP box element disrupted protein binding and abolished transcriptional activity.
Conclusions:
- Angiotensinogen gene expression in liver cells is under coordinate regulation by multiple cis-acting elements.
- These elements interact with specific DNA-binding proteins to control gene transcription.
- The SOAP box element plays a significant role in regulating angiotensinogen gene expression.