The long-term goal of this proposal is to understand, in detail, the molecular mechanisms of telomere homeostasis through comprehensive characterization of the telomere protein-DNA complex. Telomeres ensure genome integrity by facilitating chromosome end replication through telomerase. In addition, telomeres also protect the chromosome ends from DNA repair and degradation activities. Mutations in telomerase subunits or telomere components have been linked to premature aging and cancer. Maintaining proper telomere structure and length is required for accomplishing both its chromosome end replication and end protection tasks. The structure-function relationship of this complex is a central question in understanding the mechanisms of telomere homeostasis. We will exploit the genetically amendable S. pombe model system and employ a combination of biochemical, structural and genetic tools to achieve the following specific aims: 1. Map the respective protein-protein interaction interfaces between Tpz1 and its interaction partners and examine the dynamics of the Tpz1-centered complex formation in vitro. 2. Reveal the functional roles of Tpz1 mediated interactions in telomere length homeostasis and chromosome end protection. 3. Achieve a comprehensive structural analysis of the Tpz1-centered complex using single particle cryo-electron microscopy (cryo-EM) and X-ray crystallography. Accomplishment of the proposed aims will provide new and significant mechanistic insights into the structure-function relationship and the dynamics of the telomere complex, and may also provide the foundation for development of new therapeutic approaches against diseases caused by telomere dysfunction.

Public Health Relevance

Telomeres are closely involved in stem cell differentiation and cancer cell proliferation. The results of this study will lead to new mechanistic models for telomere length regulation and chromosome end protection. Therefore, valuable targets for mechanism- driven design of cancer and aging therapeutics may be identified through this research.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM098943-03
Application #
8463219
Study Section
Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
Program Officer
Carter, Anthony D
Project Start
2012-05-01
Project End
2017-01-31
Budget Start
2013-02-01
Budget End
2014-01-31
Support Year
3
Fiscal Year
2013
Total Cost
$279,220
Indirect Cost
$85,628
Name
University of California Irvine
Department
Biochemistry
Type
Schools of Medicine
DUNS #
046705849
City
Irvine
State
CA
Country
United States
Zip Code
92697
Tadeo, Xavier; Wang, Jiyong; Kallgren, Scott P et al. (2013) Elimination of shelterin components bypasses RNAi for pericentric heterochromatin assembly. Genes Dev 27:2489-99
Jun, Hyun-Ik; Liu, Jinqiang; Jeong, Heetae et al. (2013) Tpz1 controls a telomerase-nonextendible telomeric state and coordinates switching to an extendible state via Ccq1. Genes Dev 27:1917-31