ATM kinase is required for telomere elongation

ATM;telomere;Human Genetics and Molecular Biology

Lee, Stella SuyongBoeke, Jef ;

Johns Hopkins University

关键词: ATM;    telomere;    Human Genetics and Molecular Biology;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/60512/LEE-DISSERTATION-2015.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

The ATM and ATR kinase-dependent DNA damage response pathways are activated in primary human cells when telomeres are critically short (d;;Adda di Fagagna et al., 2003). Induction of telomere dysfunction through the loss of shelterin components also activates ATM or ATR-dependent signaling (Palm and de Lange, 2008). While there is a sophisticated understanding of the role of ATM and ATR in signaling telomere dysfunction, less is known about the role of these kinases in regulating telomere elongation. The ATM kinase plays a clear role in regulating telomere length maintenance in yeast (Craven et al., 2002), yet a role in humans and mice is less clear in part due to infertility of ATM-/- mice. Given the conserved role of ATM in telomere length regulation in yeast, we wanted to revisit the role of the ATM kinase in telomere elongation in mammalian cells. To examine the role of ATM, and other genes, we developed an assay that can rapidly identify effectors of telomere length, even if these regulators are essential genes. This assay was inspired by an assay from yeast (Diede and Gottschling, 1999), and is referred here as ADDIT (Addition of de novo initiated telomeres). Briefly, in a stable mouse fibroblast cell line, a single chromosome was modified to contain a unique I-Sce1 restriction site placed adjacent to short telomere ;;seed’ sequence that can be elongated by telomerase. When I-Sce1 cut is induced in vivo, the telomere seed is exposed allowing telomere elongation. We verified telomerase-dependent telomere addition occurs in vivo over just one cell cycle.Using this assay we found that blocking ATM kinase with the specific inhibitor KU33955 or with siRNA, blocks telomere elongation. Inhibition of ATM kinase activity also prevented bulk telomere elongation by telomerase overexpression and shortened telomere lengths, further supporting the essential role of ATM in telomere length regulation. The ADDIT assay will allow rapid dissection of the ATM pathway of telomere length regulation in addition to identification of new regulators of telomere length. The assay will provide insights into telomere length homeostasis and may identify potential targets for future therapeutics.