Telomerase serves two independent and critical roles in normal stem cells and in cancer. Telomerase is reactivated in approximately 90% of human cancers, making telomerase one of the most commonly dysregulated pathways in human tumorigenesis. As a reverse transcriptase that synthesizes telomere repeats, telomerase maintains telomere length and stability to prevent the severe adverse consequences of telomere dysfunction, which include senescence, apoptosis and massive chromosome instability. In this role, telomerase supports the enormous proliferative capacity of both stem cells and cancer cells. In mediating the ability of cancer cells to proliferate in an immortal fashion, telomerase requires both TERT, the telomerase protein component, and TERC, the telomerase RNA component, which together add telomere sequences to chromosome ends. We recently identified a second function for TERT in facilitating the proliferation of quiescent, multipotent stem cells. This important new role for TERT in stem cell activation does not require TERC and is therefore independent of TERT's function in telomere synthesis. Thus, TERT acts in two discrete pathways - telomere synthesis and stem cell activation - that together are likely crucial for human cancer development. Despite the importance of TERT in these two critical pathways, TERT protein regulation remains poorly understood. The goal of this project is to understand TERT protein regulation, specifically how TERT protein stability is controlled. Consistent with its role as a critical regulator, we find that TERT protein is unstable, ubiquitinated and destroyed by the proteasome in human cells. Furthermore, we have employed powerful mass spectrometry tools to isolate a ubiquitin E3 ligase that specifically associates with TERT in human cancer cells. We propose: (1) To understand the role of destruction in regulating TERT protein function (2) To determine the function of the TERT-Associated Ubiquitin E3 Ligase (TAUL1) in TERT protein stability, cellular immortalization and cancer and (3) To understand the function of TAUL1 through analysis of a conditional knockout mouse.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA125453-05
Application #
7898698
Study Section
Cancer Molecular Pathobiology Study Section (CAMP)
Program Officer
Pelroy, Richard
Project Start
2006-09-26
Project End
2013-03-31
Budget Start
2010-08-01
Budget End
2013-03-31
Support Year
5
Fiscal Year
2010
Total Cost
$276,183
Indirect Cost
Name
Stanford University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Kareta, Michael S; Gorges, Laura L; Hafeez, Sana et al. (2015) Inhibition of pluripotency networks by the Rb tumor suppressor restricts reprogramming and tumorigenesis. Cell Stem Cell 16:39-50
Pech, Matthew F; Garbuzov, Alina; Hasegawa, Kazuteru et al. (2015) High telomerase is a hallmark of undifferentiated spermatogonia and is required for maintenance of male germline stem cells. Genes Dev 29:2420-34
Freund, Adam; Zhong, Franklin L; Venteicher, Andrew S et al. (2014) Proteostatic control of telomerase function through TRiC-mediated folding of TCAB1. Cell 159:1389-403
Batista, Luis F Z; Artandi, Steven E (2013) Understanding telomere diseases through analysis of patient-derived iPS cells. Curr Opin Genet Dev 23:526-33
Zhong, Franklin L; Batista, Luis F Z; Freund, Adam et al. (2012) TPP1 OB-fold domain controls telomere maintenance by recruiting telomerase to chromosome ends. Cell 150:481-94
Shkreli, Marina; Sarin, Kavita Y; Pech, Matthew F et al. (2011) Reversible cell-cycle entry in adult kidney podocytes through regulated control of telomerase and Wnt signaling. Nat Med 18:111-9
Zhong, Franklin; Savage, Sharon A; Shkreli, Marina et al. (2011) Disruption of telomerase trafficking by TCAB1 mutation causes dyskeratosis congenita. Genes Dev 25:11-6
Batista, Luis F Z; Pech, Matthew F; Zhong, Franklin L et al. (2011) Telomere shortening and loss of self-renewal in dyskeratosis congenita induced pluripotent stem cells. Nature 474:399-402
Venteicher, Andrew S; Abreu, Eladio B; Meng, Zhaojing et al. (2009) A human telomerase holoenzyme protein required for Cajal body localization and telomere synthesis. Science 323:644-8
Park, Jae-Il; Venteicher, Andrew S; Hong, Ji Yeon et al. (2009) Telomerase modulates Wnt signalling by association with target gene chromatin. Nature 460:66-72

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