Expression cloning of multiple human cDNAs that complement the phenotypic defects of ataxia-telangiectasia group D fibroblasts
- Yale Univ., New Haven, CT (United States)
Ataxia-telangiectasia (A-T) is an inherited human disease of unknown etiology associated with neurologic degeneration, immune dysfunction, cancer risk, and genetic instability. A-T cells are sensitive to ionizing radiation and radiomimetic drugs, offering the possibility of cloning A-T genes by phenotypic complementation. The authors have used this sensitivity to isolate the first human cDNAs reported to complement A-T cells in culture. Complementation group D A-T fibroblasts were transfected with an episomal vector-based human cDNA library, [approximately]610,000 resultant transformants were treated with the radiomimetic drug streptonigrin-resistent, and nine unrelated cDNAs were recovered from 20 surviving stretptonigrin-resistant clones. Five cDNAs were mapped, but none localized to 11q23, the site of A-T D fibroblasts on secondary transfection. One cDNA was identified as a fragment of dek, a gene involved in acute myeloid leukemia. The dek cDNA fragment and pCAT4.5, a 4.5-kb cDNA that mapped to 17p11, independently complemented three different phenotypic abnormalities of A-T D fibroblasts (mutagen sensitivity, hyperrecombination, and radio-resistant DNA synthesis). The pCAT4.5 cDNA did not complement the mutagen sensitivity of an A-T group C fibroblast line, suggesting that it represents a candidate disease gene for group D A-T. These results indicate that phenotypic complementation alone is insufficient evidence to prove that a candidate cDNA is an A-T disease gene. The complementing cDNAs may represent previously uncharacterized genes that function in the same pathway as does the A-T gene product(s) in the regulation of cellular responses to DNA damage. 38 refs., 7 figs., 3 tabs.
- OSTI ID:
- 5296239
- Journal Information:
- American Journal of Human Genetics; (United States), Vol. 53:6; ISSN 0002-9297
- Country of Publication:
- United States
- Language:
- English
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