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Structure and variability of human chromosome ends.
T de Lange1, L Shiue, R M Myers
1Department of Microbiology and Immunology, University of California, San Francisco 94143.
Molecular and Cellular Biology
|February 1, 1990
Summary
Researchers cloned human telomere DNA, revealing a subtelomeric repeat and variable TTAGGG repeat regions. Human telomeres shorten and become unstable in somatic cells and tumors.
Area of Science:
- Genetics
- Molecular Biology
- Genomics
Background:
- Mammalian telomeres consist of TTAGGG repeat arrays.
- Understanding telomere structure is crucial for chromosome stability.
Purpose of the Study:
- To define the sequences and arrangement at the ends of human chromosomes.
- To develop a cloning strategy for telomere-associated DNA.
Main Methods:
- Developed a direct cloning strategy for telomere-associated DNA.
- Utilized a telomere enrichment procedure based on restriction endonuclease cutting sites.
- Isolated nineteen (TTAGGG)n-bearing plasmids.
Main Results:
- Identified telomere-flanking sequences, including a subtelomeric repeat present at 10-25% of human chromosome ends.
- The subtelomeric repeat is 4 kb, shows high polymorphism, and undergoes methylation.
- Human telomeres are shorter and more heterogeneous in somatic cells than in sperm, with further reduction in tumors.
Conclusions:
- The subtelomeric repeat is a useful tool for human chromosome characterization in hybrid cell lines.
- Human telomeres are unstable in somatic cells and tumors, undergoing continuous sequence loss.