The ends of linear chromosomes, called telomeres, are essential for genomic stability and normal cellular growth. In most organisms, the primary mechanism for complete replication of telomeres relies on the enzyme telomerase. Loss of telomerase function results in a progressive decline in telomere length that heralds replicative senescence, which has been postulated to contribute to organismal aging. This enzyme is also reactivated in the majority of human tumors, indicating that telomerase is a likely target for anti-cancer therapeutics. A full appreciation of the contribution of telomere replication to these two important aspects of human biology will require a molecular understanding of how telomerase is regulated in vivo. We are using the budding yeast, S. cerevisiae, as a system for dissection of this problem, based on the assumption that what we learn in yeast will translate to human cells. Past work in our laboratory has identified three proteins, Estl, Est2 and Est3, that are subunits of yeast telomerase. The Est2 protein is the catalytic reverse transcriptase component, whereas Estl and Est3, which are dispensable for enzyme catalysis but essential in vivo for telomere replication, are positive regulatory subunits of the telomerase holoenzyme. Our genetic and biochemical analysis has shown that the Estl and Est3 subunits contribute multiple, and functionally distinct, regulatory roles to telomere replication. We have also characterized potential regulatory domains of the TLC1 RNA subunit of the yeast telomerase enzyme. Additional recent studies have led to the identification of additional genes required for regulation of telomere replication, including a potential negative regulator of telomerase. In this application, we propose a set of experiments intended to form an integrated picture of how these positive and negative regulators of telomerase control telomere replication.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37AG011728-19
Application #
8220818
Study Section
Special Emphasis Panel (NSS)
Program Officer
Guo, Max
Project Start
1993-09-20
Project End
2014-01-31
Budget Start
2012-02-01
Budget End
2014-01-31
Support Year
19
Fiscal Year
2012
Total Cost
$373,571
Indirect Cost
$178,495
Name
Salk Institute for Biological Studies
Department
Type
DUNS #
078731668
City
La Jolla
State
CA
Country
United States
Zip Code
92037
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Tucey, Timothy M; Lundblad, Victoria (2013) A yeast telomerase complex containing the Est1 recruitment protein is assembled early in the cell cycle. Biochemistry 52:1131-3
Ballew, Bari J; Lundblad, Victoria (2013) Multiple genetic pathways regulate replicative senescence in telomerase-deficient yeast. Aging Cell 12:719-27
Lee, Jaesung; Mandell, Edward K; Rao, Timsi et al. (2010) Investigating the role of the Est3 protein in yeast telomere replication. Nucleic Acids Res 38:2279-90
Lee, Jaesung; Mandell, Edward K; Tucey, Timothy M et al. (2008) The Est3 protein associates with yeast telomerase through an OB-fold domain. Nat Struct Mol Biol 15:990-7
Chappell, Andrew S; Lundblad, Victoria (2004) Structural elements required for association of the Saccharomyces cerevisiae telomerase RNA with the Est2 reverse transcriptase. Mol Cell Biol 24:7720-36
Evans, Sara K; Lundblad, Victoria (2002) The Est1 subunit of Saccharomyces cerevisiae telomerase makes multiple contributions to telomere length maintenance. Genetics 162:1101-15
Hughes, T R; Evans, S K; Weilbaecher, R G et al. (2000) The Est3 protein is a subunit of yeast telomerase. Curr Biol 10:809-12

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