A dyskerin motif reactivates telomerase activity in X-linked dyskeratosis congenita and in telomerase-deficient human cells.
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.
Machado-Pinilla
Rosario
R
Translational Oncology Unit, Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Cientificas/Universidad Autónoma de Madrid, C/Arturo Duperier 4, Madrid, Spain.
Sánchez-Pérez
Isabel
I
Murguía
José Ramón
JR
Sastre
Leandro
L
Perona
Rosario
R
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000737:chemistry*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D004351:Drug Resistance / Q000187:drug effects; D019871:Dyskeratosis Congenita / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D012313:RNA / Q000378:metabolism; D013329:Structure-Activity Relationship; D019098:Telomerase / Q000037:antagonists & inhibitors / Q000172:deficiency* / Q000378:metabolism*
D018797:Cell Cycle Proteins; C112148:DKC1 protein, human; D004791:Enzyme Inhibitors; C000603663:GSE24.2 peptide; D009687:Nuclear Proteins; D010446:Peptide Fragments; D016271:Proto-Oncogene Proteins c-myc; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase; D002945:Cisplatin