Our long-term goal is to determine the mechanisms of telomerase regulation during development. The hTERT gene, encoding the limiting subunit of human telomerase, is primarily regulated at the level of transcription. It is highly expressed in pluripotent stem cells, but stringently repressed in most somatic cells. Regulation of transcription during development and differentiation often involves distal elements and chromatin reorganization, in addition to proximal promoter elements. We previously showed that the endogenous hTERT locus was embedded in a condensed chromatin domain in many somatic cells. Consistent with the vital role of chromatin in its tight regulation, we found that an episomal hTERT locus in human fibroblasts was not subjected to repression, whereas a chromosomally integrated hTERT locus recapitulated its native regulation. To study the mechanisms of hTERT repression, we developed a novel technical platform, the recombinase-mediated BAC targeting or RMBT method, for targeted integration of single-copy BAC reporters into specified chromosomal sites. This technique enables us to study the regulation of hTERT gene in its native genomic context. Here, we hypothesize that 1) the interplay between distal elements and core promoter in their native chromatin contexts is important for hTERT repression in somatic cells and reactivation in cancer cells; and 2) polymorphic regulatory elements of the hTERT gene impact human aging and tumorigenesis. We propose three specific aims: 1) determine the recruitment of corepressor complexes and their roles in hTERT repression; 2) determine the regulation of hTERT promoter by Ets family proteins in normal and cancer cells; 3) determine the function and genetic variation of a polymorphic element in hTERT regulation and human longevity.

Public Health Relevance

Telomeres are ends of linear chromosomes and essential for long-term cell proliferation and survival. Telomerase, the enzyme that elongates telomeres, plays an important role in cancers and aging-related diseases. This grant application is proposed to determine the mechanisms of telomerase regulation in normal human cells and cancer cells, as well as how genetic diversities of the telomerase gene impact human longevity.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Cellular Mechanisms in Aging and Development Study Section (CMAD)
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Gaillard, Shawn R
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Washington State University
Schools of Pharmacy
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Cheng, De; Wang, Shuwen; Jia, Wenwen et al. (2017) Regulation of human and mouse telomerase genes by genomic contexts and transcription factors during embryonic stem cell differentiation. Sci Rep 7:16444
Cheng, De; Zhao, Yuanjun; Wang, Shuwen et al. (2017) Repression of telomerase gene promoter requires human-specific genomic context and is mediated by multiple HDAC1-containing corepressor complexes. FASEB J 31:1165-1178
Zhang, Fan; Cheng, De; Wang, Shuwen et al. (2016) Human Specific Regulation of the Telomerase Reverse Transcriptase Gene. Genes (Basel) 7:
Cheng, De; Zhao, Yuanjun; Wang, Shuwen et al. (2015) Human Telomerase Reverse Transcriptase (hTERT) Transcription Requires Sp1/Sp3 Binding to the Promoter and a Permissive Chromatin Environment. J Biol Chem 290:30193-203
Block, Keith I; Gyllenhaal, Charlotte; Lowe, Leroy et al. (2015) Designing a broad-spectrum integrative approach for cancer prevention and treatment. Semin Cancer Biol 35 Suppl:S276-S304
Yaswen, Paul; MacKenzie, Karen L; Keith, W Nicol et al. (2015) Therapeutic targeting of replicative immortality. Semin Cancer Biol 35 Suppl:S104-S128
Ma, Yanchun; Hao, Sijie; Wang, Shuwen et al. (2015) A Combinatory Strategy for Detection of Live CTCs Using Microfiltration and a New Telomerase-Selective Adenovirus. Mol Cancer Ther 14:835-43
Zhao, Yuanjun; Cheng, De; Wang, Shuwen et al. (2014) Dual roles of c-Myc in the regulation of hTERT gene. Nucleic Acids Res 42:10385-98
Zhao, Yuanjun; Wang, Shuwen; Zhu, Jiyue (2011) A multi-step strategy for BAC recombineering of large DNA fragments. Int J Biochem Mol Biol 2:199-206
Jia, Wenwen; Wang, Shuwen; Horner, James W et al. (2011) A BAC transgenic reporter recapitulates in vivo regulation of human telomerase reverse transcriptase in development and tumorigenesis. FASEB J 25:979-89

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