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.

National Institute of Health (NIH)
National Institute on Aging (NIA)
Method to Extend Research in Time (MERIT) Award (R37)
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Special Emphasis Panel (NSS)
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Mccormick, Anna M
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Salk Institute for Biological Studies
La Jolla
United States
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Rao, Timsi; Lubin, Johnathan W; Armstrong, Geoffrey S et al. (2014) Structure of Est3 reveals a bimodal surface with differential roles in telomere replication. Proc Natl Acad Sci U S A 111:214-8
Tucey, Timothy M; Lundblad, Victoria (2014) Regulated assembly and disassembly of the yeast telomerase quaternary complex. Genes Dev 28:2077-89
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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
(2013) Correction to A Yeast Telomerase Complex Containing the Est1 Recruitment Protein Is Assembled Early in the Cell Cycle Biochemistry 52:5027
Lundblad, Victoria (2012) Telomere end processing: unexpected complexity at the end game. Genes Dev 26:1123-7
Lubin, Johnathan W; Tucey, Timothy M; Lundblad, Victoria (2012) The interaction between the yeast telomerase RNA and the Est1 protein requires three structural elements. RNA 18:1597-604
Paschini, Margherita; Mandell, Edward K; Lundblad, Victoria (2010) Structure prediction-driven genetics in Saccharomyces cerevisiae identifies an interface between the t-RPA proteins Stn1 and Ten1. Genetics 185:11-21
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

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