ATM-dependent DNA damage response constrains cell growth and drives clonal hematopoiesis in telomere biology disorders
Christopher M. Sande, … , Timothy S. Olson, Daria V. Babushok
Christopher M. Sande, … , Timothy S. Olson, Daria V. Babushok
Published April 3, 2025
Citation Information: J Clin Invest. 2025;135(8):e181659. https://doi.org/10.1172/JCI181659.
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Research Article Hematology Oncology

ATM-dependent DNA damage response constrains cell growth and drives clonal hematopoiesis in telomere biology disorders

Abstract

Telomere biology disorders (TBDs) are genetic diseases caused by defective telomere maintenance. TBD patients often develop bone marrow failure and have an increased risk of myeloid neoplasms. To better understand the factors underlying hematopoietic outcomes in TBD, we comprehensively evaluated acquired genetic alterations in hematopoietic cells from 166 pediatric and adult TBD patients. Of these patients, 47.6% (28.8% of children, 56.1% of adults) had clonal hematopoiesis. Recurrent somatic alterations involved telomere maintenance genes (7.6%), spliceosome genes (10.4%, mainly U2AF1 p.S34), and chromosomal alterations (20.2%), including 1q gain (5.9%). Somatic variants affecting the DNA damage response (DDR) were identified in 21.5% of patients, including 20 presumed loss-of-function variants in ataxia-telangiectasia mutated (ATM). Using multimodal approaches, including single-cell sequencing, assays of ATM activation, telomere dysfunction-induced foci analysis, and cell-growth assays, we demonstrate telomere dysfunction–induced activation of the ATM-dependent DDR pathway with increased senescence and apoptosis in TBD patient cells. Pharmacologic ATM inhibition, modeling the effects of somatic ATM variants, selectively improved TBD cell fitness by allowing cells to bypass DDR-mediated senescence without detectably inducing chromosomal instability. Our results indicate that ATM-dependent DDR induced by telomere dysfunction is a key contributor to TBD pathogenesis and suggest dampening hyperactive ATM-dependent DDR as a potential therapeutic intervention.

Authors

Christopher M. Sande, Stone Chen, Dana V. Mitchell, Ping Lin, Diana M. Abraham, Jessie Minxuan Cheng, Talia Gebhard, Rujul J. Deolikar, Colby Freeman, Mary Zhou, Sushant Kumar, Michael Bowman, Robert L. Bowman, Shannon Zheng, Bolormaa Munkhbileg, Qijun Chen, Natasha L. Stanley, Kathy Guo, Ajibike Lapite, Ryan Hausler, Deanne M. Taylor, James Corines, Jennifer J.D. Morrissette, David B. Lieberman, Guang Yang, Olga Shestova, Saar Gill, Jiayin Zheng, Kelcy Smith-Simmer, Lauren G. Banaszak, Kyle N. Shoger, Erica F. Reinig, Madilynn Peterson, Peter Nicholas, Amanda J. Walne, Inderjeet Dokal, Justin P. Rosenheck, Karolyn A. Oetjen, Daniel C. Link, Andrew E. Gelman, Christopher R. Reilly, Ritika Dutta, R. Coleman Lindsley, Karyn J. Brundige, Suneet Agarwal, Alison A. Bertuch, Jane E. Churpek, Laneshia K. Tague, F. Brad Johnson, Timothy S. Olson, Daria V. Babushok

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Figure 8

Increased ATM target phosphorylation in TERC-mutated compared with control fibroblasts.

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Increased ATM target phosphorylation in TERC-mutated compared with contr...
(A) A representative Western blot image showing phosphorylation of ATM target proteins in TERC-mutated compared with control fibroblasts. Experimental condition (+/- ATMi) and experimental induction of DDR using x-ray radiation (XRT) are shown at the top of each lane. Vinculin was used as a loading control for ATM, and GAPDH was used as a loading control for KAP1 and Chk2. (B and C) Image densitometry analysis of replicate Western blot experiments was performed in ImageJ and summarized in B for pATM/ATM, n = 4 and (C) for pKAP1/KAP1, n = 7. Quantified densitometry values for each protein were normalized to their respective loading control. The ratio of phosphorylated compared with total protein levels in each experiment, along with the summary statistics (mean and SD) are shown in bar plots. Statistical analysis was performed using 2-tailed paired t tests. (D) Quantitative analysis of average senescence-associated β-galactosidase expression, normalized per cell number in passage 10 primary skin fibroblasts from 2 non-TBD controls and 2 TBD patients bearing different TERC variants grown with or without 20 nM ATMi; (E) Shown are representative β-galactosidase staining images. (F) Quantitative analysis of average senescence-associated β-galactosidase expression, normalized per cell number, in primary skin fibroblasts from non-TBD control and a TBD patient with DKC1 mutation, alongside representative images (G), demonstrating the progressive increase in senescence-associated β-galactosidase expression with successive passages in TBD patients’ cells that is significantly alleviated by 20 nM ATMi. In D–G, n = 10–16 wide-field images at 10× magnification per each condition, quantified in Fiji. Statistical analysis was performed in GraphPad Prism using 2-way ANOVA. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.