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Blood. 2008 Mar 1;111(5):2606-14. Epub 2007 Dec 5.

A dyskerin motif reactivates telomerase activity in X-linked dyskeratosis congenita and in telomerase-deficient human cells.

Author information

1
Translational Oncology Unit, Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Cientificas/Universidad Autónoma de Madrid, C/Arturo Duperier 4, Madrid, Spain.

Abstract

Dyskerin gene is mutated in patients with X-linked dyskeratosis congenita (X-DC), which results in greatly reduced levels of telomerase activity. A genetic suppressor element (GSE) termed GSE24-2 has been isolated in a screening for cisplatin resistance. GSE24-2-expressing cells presented impaired telomerase inhibition following in vitro exposure to chemotherapies, such as cisplatin, or telomerase inhibitors. The promoter of the telomerase component hTERT was constitutively activated in GSE24-2 cells in a c-myc expression-dependent manner. Deletion analyses and mutagenesis of the human c-myc promoter demonstrated that the target sequence for activation was the nuclease hypersensitive element-III (NHEIII) site located upstream to the P1 region of the promoter. Further, expression of GSE24-2 in cell lines derived from patients with X-DC and in VA13 cells induced increased hTERT RNA and hTR levels and recovery of telomerase activity. Finally, expression of GSE24-2 was able to rescue X-DC fibroblasts from premature senescence. These data demonstrate that this domain of dyskerin plays an important role in telomerase maintenance following cell insults such as cisplatin treatment, and in telomerase-defective cells in patients with X-DC. The expression of this dyskerin fragment has a dominant function in X-DC cells and could provide the basis for a therapeutic approach to this disease.

PMID:
18057229
DOI:
10.1182/blood-2007-04-083261
[Indexed for MEDLINE]
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