ABSTRACT
Recent studies show that the structure integrality and function are more important than the length of telomere in maintaining tumor cells reproduction and proliferation.Mammalian telomeres bound by a specialized six-protein(TRF1,TRF2,TIN2,RAP1,POT1 and TPP1 )complex known as telosome or shelterin,has fundamental role in the regulation of telomere activity,maintaining the length and protecting telomere chromosome terminal.Telosome is involved in the complex regulation of cell mitosis process.The study of the role of telomere binding protein complex in tumorigenesis is very important for searching new methods of tumor diagnosis and treatment.
ABSTRACT
The gradual loss of telomeric DNA can contribute to replicative senescence and thus, having longer telomeric DNA is generally considered to provide a longer lifespan. Maintenance and stabilization of telomeric DNA is assisted by binding of multiple DNA-binding proteins, including those involved in double strand break (DSB) repair. We reasoned that declining DSB repair capacity and increased telomere shortening in aged individuals may be associated with decreased expression of DSB repair proteins capable of telomere binding. Our data presented here show that among the DSB repair proteins tested, only the expression of Ku70 and Mre11 showed statistically significant age-dependent changes in human lymphocytes. Furthermore, we found that expressions of Ku70 and Mre11 are statistically correlated, which indicate that the function of Ku70 and Mre11 may be related. All the other DSB repair proteins tested, Sir2, TRF1 and Ku80, did not show any significant differences upon aging. In line with these data, people who live in the regional community (longevity group), which was found to have statistically longer average life span than the rest area, shows higher level of Ku70 expression than those living in the neighboring control community. Taken together, our data show, for the first time, that Ku70 and Mre11 may represent new biomarkers for aging and further suggest that maintenance of higher expression of Ku70 and Mre11 may be responsible for keeping longer life span observed in the longevity group.
Subject(s)
Middle Aged , Humans , Aged, 80 and over , Aged , Adult , Telomere/genetics , Longevity , DNA-Binding Proteins/metabolism , DNA Repair/genetics , DNA/genetics , Cellular Senescence/physiology , CD4-Positive T-Lymphocytes/metabolism , Antigens, Nuclear/metabolism , Aging/physiologyABSTRACT
Objective To clone the telomere-associated protein T-STAR and study the relationship between T-STAR and the telomerase catalyzed subunit hTERT in mammalian cells. Method The expression vector pGBKT7-hTERT was constructed and acted as a decoy in cDNA library screened by yeast two-hybrid technology. Recombinant vectors pVP16-T-STAR and pM-hTERT were constructed and co-transfected with report gene CAT into SGC-7901 cells with liposome. pM-53+pVP16-T and pM3-VP16 were introduced as positive controls, pM-53+pVP16-CP as negative control, and pM-hTERT+pVP16, pM+pVP16-T-STAR and pM+pVP16 as crossing negative controls. The expression of CAT was assayed by ELISA. Results The eukaryotic expression vector pGBKT7-hTERT was successfully constructed. One positive clone achieved by cDNA library screening was sequenced and compared with the isogenous sequences in GenBank by Blast software via Internet. As a result, T-STAR, a recorded cDNA sequence was obtained. The recombinant vectors of pVP16-T-STAR and pM-hTERT were constructed successfully and co-transformed into gastric cancer cells SGC-7901. The OD value of reported gene CAT was 0.258, which was significantly higher than that of the negative and crossing negative controls (0.002-0.015). It revealed that T-STAR interacted with hTERT in the mammalian cells. Conclusions T-STAR interacts with hTERT in the gastric cancer cells. T-STAR may be a new member of telomere-associated protein, and it participates in the regulation of telomerase through hTERT.