Telomeres play an essential role at the interface between cellular aging and carcinogenesis because they are highly sensitive to oxidative stress. Oxidative stress, or the excess of free radicals, is a ubiquitous source of DNA damage humans experience from normal metabolism, physical stress, exogenous sources such as pollution and solar radiation, and by-products of immune cell signaling. While a link between telomere attrition and oxidative stress exists, there have been no reports on how direct oxidative base damage to telomeric DNA impacts normal cell biology. Our group has developed the first system to induce the common oxidative lesion 8-oxo-guanine (8oxoG) specifically at telomeres by fusing a fluorogen activated peptide (FAP) to the telomere binding protein TRF1. We have generated clonal cell lines that have homogenous FAP-TRF1 expression at the telomere, and find that after a single induction of telomeric 8oxoG, normal cells exhibit a growth arrest, which we did not observe in two cancer cell lines. The hypothesis of this fellowship is that telomeric 8oxoG is sufficient to produce a DDR in normal cells that induces growth arrest, independent of telomere shortening, that depends on the p53/p21 signaling axis. Moreover, following induction of telomeric 8oxoG we observe an increase in the number of micronuclei as early as one day after treatment. This project will also address how these micronuclei are forming, if they are dependent on DNA replication, and if they are sensed by the cGAS/STING axis. Competition of this project will delineate for the first time the contribution of telomeric oxidative stress to cellular outcomes related to aging and cancer. This work will have general applications to all humans, but will also inform the biology of age-related diseases that are associated with increased levels of oxidative stress, and may promote health-span in either case.This fellowship also allows for the acquisition of new skills related to the aims of the project, and has outlines specific mentors for each. This includes single molecule analyses of telomere replication, live-cell imaging, RNA-sequencing, and detection of signaling molecules related to the immune system. Moreover, career development is also a focus of this fellowship. It includes plans to attend workshops related to experimental techniques and scientific writing, in addition to attending national and international conferences to present the findings of this research project.
Telomeres are essential genetic structures at the interface between cellular aging and carcinogenesis. In this fellowship I will use a model of telomere specific oxidative base damage in normal cells to determine the DNA damage signaling response, immune signaling status, and cellular outcomes in response to a single induction of telomere oxidative stress. This work will provide meaningful insight on the contribution telomere base damage has on cellular aging, and will inform future basic and clinical research related to promoting human healthspan and preventing or delaying aging-related disease including cancer.
