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Genomic instability in both wild-type and telomerase null MEFs
Ling-Yang Hao1, Carol W Greider
1Graduate Program in Human Genetics, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, 725 N Wolfe Street, Baltimore, MD 21205, USA.
Chromosoma
|July 20, 2004
Summary
Mouse embryonic fibroblasts lacking telomerase (mTR-/-) initially show genomic instability. However, wild-type cells develop similar instability later, suggesting crisis MEFs are not genetically stable. Radiosensitivity is lost post-crisis in both cell types.
Area of Science:
- Genetics
- Cell Biology
- Cancer Research
Background:
- Telomeres protect chromosome ends and shorten with each cell division.
- Telomerase is an enzyme that maintains telomere length.
- Absence of telomerase leads to telomere attrition and genomic instability.
Purpose of the Study:
- To investigate chromosome instability in mouse embryonic fibroblasts (MEFs) lacking telomerase (mTR-/-) compared to wild-type (WT) MEFs.
- To assess the impact of telomere shortening on genomic stability and radiosensitivity.
- To evaluate the genetic stability of post-crisis MEFs.
Main Methods:
- Establishing late-generation mTR-/- and WT mouse embryonic fibroblast (MEF) lines.
- Analyzing metaphases using telomere fluorescence in situ hybridization (FISH) and spectral karyotyping (SKY).
- Assessing radiosensitivity and DNA damage response (p53, gamma-H2AX phosphorylation) after irradiation.
Main Results:
- Early passage mTR-/- MEFs exhibited increased chromosome end-to-end fusions and radiosensitivity.
- Later passage WT MEFs showed comparable or higher genomic instability than mTR-/- MEFs.
- Post-crisis mTR-/- and WT MEFs lost radiosensitivity and DNA damage checkpoint function (p53, gamma-H2AX).
Conclusions:
- Telomere attrition in mTR-/- MEFs induces genomic instability.
- Post-crisis MEFs, including WT, exhibit significant genomic instability and loss of DNA damage response.
- Genetic instability in MEFs increases over time, challenging the concept of genetically defined post-crisis cell lines.