Topic
TEP1
About: TEP1 is a research topic. Over the lifetime, 68 publications have been published within this topic receiving 27067 citations. The topic is also known as: TLP1 & TP1.
Papers published on a yearly basis
Papers
TL;DR: A highly sensitive assay for measuring telomerase activity was developed in this paper, which showed that telomerases appear to be stringently repressed in normal human somatic tissues but reactivated in cancer, where immortal cells are likely required to maintain tumor growth.
Abstract: Synthesis of DNA at chromosome ends by telomerase may be necessary for indefinite proliferation of human cells. A highly sensitive assay for measuring telomerase activity was developed. In cultured cells representing 18 different human tissues, 98 of 100 immortal and none of 22 mortal populations were positive for telomerase. Similarly, 90 of 101 biopsies representing 12 human tumor types and none of 50 normal somatic tissues were positive. Normal ovaries and testes were positive, but benign tumors such as fibroids were negative. Thus, telomerase appears to be stringently repressed in normal human somatic tissues but reactivated in cancer, where immortal cells are likely required to maintain tumor growth.
7,482 citations
TL;DR: All major types of cancer have been screened and the presence of telomerase activity has been detected in the vast majority of cases, and a summary, in table form, of the current data is provided.
2,914 citations
TL;DR: Human cell lines that expressed hTR mutated in the template region generated the predicted mutant telomerase activity, and cells transfected with an antisense hTR lost telomeric DNA and began to die after 23 to 26 doublings.
Abstract: Eukaryotic chromosomes are capped with repetitive telomere sequences that protect the ends from damage and rearrangements. Telomere repeats are synthesized by telomerase, a ribonucleic acid (RNA)-protein complex. Here, the cloning of the RNA component of human telomerase, termed hTR, is described. The template region of hTR encompasses 11 nucleotides (5'-CUAACCCUAAC) complementary to the human telomere sequence (TTAGGG)n. Germline tissues and tumor cell lines expressed more hTR than normal somatic cells and tissues, which have no detectable telomerase activity. Human cell lines that expressed hTR mutated in the template region generated the predicted mutant telomerase activity. HeLa cells transfected with an antisense hTR lost telomeric DNA and began to die after 23 to 26 doublings. Thus, human telomerase is a critical enzyme for the long-term proliferation of immortal tumor cells.
2,412 citations
TL;DR: In this paper, the homologous genes from the fission yeast Schizosaccharomyces pombe and human are identified and the proposed telomerase catalytic subunits represent a deep branch in the evolution of reverse transcriptases.
Abstract: Catalytic protein subunits of telomerase from the ciliate Euplotes aediculatus and the yeast Saccharomyces cerevisiae contain reverse transcriptase motifs. Here the homologous genes from the fission yeast Schizosaccharomyces pombe and human are identified. Disruption of the S. pombe gene resulted in telomere shortening and senescence, and expression of mRNA from the human gene correlated with telomerase activity in cell lines. Sequence comparisons placed the telomerase proteins in the reverse transcriptase family but revealed hallmarks that distinguish them from retroviral and retrotransposon relatives. Thus, the proposed telomerase catalytic subunits are phylogenetically conserved and represent a deep branch in the evolution of reverse transcriptases.
2,301 citations
TL;DR: In this article, the authors measured telomere length, telomerase activity and chromosome rearrangements in human cells before and after transformation with SV40 or Ad5 and found that telomeres shortened by approximately 65 bp/generation during the lifespan of the cultures.
Abstract: Loss of telomeric DNA during cell proliferation may play a role in ageing and cancer. Since telomeres permit complete replication of eukaryotic chromosomes and protect their ends from recombination, we have measured telomere length, telomerase activity and chromosome rearrangements in human cells before and after transformation with SV40 or Ad5. In all mortal populations, telomeres shortened by approximately 65 bp/generation during the lifespan of the cultures. When transformed cells reached crisis, the length of the telomeric TTAGGG repeats was only approximately 1.5 kbp and many dicentric chromosomes were observed. In immortal cells, telomere length and frequency of dicentric chromosomes stabilized after crisis. Telomerase activity was not detectable in control or extended lifespan populations but was present in immortal populations. These results suggest that chromosomes with short (TTAGGG)n tracts are recombinogenic, critically shortened telomeres may be incompatible with cell proliferation and stabilization of telomere length by telomerase may be required for immortalization.
2,097 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 1 |
| 2018 | 2 |
| 2017 | 1 |
| 2016 | 1 |
| 2015 | 1 |
| 2014 | 1 |