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Replication structure of the human beta-globin gene domain
D Kitsberg1, S Selig, I Keshet
1Department of Cellular Biochemistry, Hebrew University Medical School, Jerusalem, Israel.
Nature
|December 9, 1993
Summary
Researchers identified a specific DNA replication origin in human cells, proving discrete origins exist. This origin controls DNA synthesis timing in the beta-globin gene domain, regardless of cell type.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Animal cell genomes are organized into replicons (50-300 kb) with specific origins of replication.
- Viral replication origins are regulated by cis-acting elements and can be cell-type specific.
- Little is known about the organization and control of endogenous, tissue-specific gene replication.
Purpose of the Study:
- To investigate the organization and control of endogenous tissue-specific gene replication.
- To identify and characterize replication origins within the human beta-like globin domain.
Main Methods:
- Replication direction assay used to analyze DNA fragments (>200 kb) of the human beta-like globin domain.
- Examination of DNA replication patterns in both expressing and non-expressing cells.
Main Results:
- A single, bidirectional replication origin was identified upstream of the beta-globin gene.
- This origin initiates DNA synthesis in both expressing (early replication) and non-expressing (late replication) cells.
- Deletion of the origin (as in haemoglobin Lepore syndrome) abolished bidirectional synthesis and reversed replication direction.
Conclusions:
- Provides the first genetic evidence for specific, discrete origins of replication in animal cells.
- Demonstrates the crucial role of a defined origin in controlling DNA replication timing and direction within a gene domain.
- Highlights the significance of replication origins in the context of genetic disorders like haemoglobin Lepore syndrome.