Frataxin deficiency promotes endothelial senescence in pulmonary hypertension
Miranda K. Culley, … , Thomas Bertero, Stephen Y. Chan
Miranda K. Culley, … , Thomas Bertero, Stephen Y. Chan
Published April 27, 2021
Citation Information: J Clin Invest. 2021;131(11):e136459. https://doi.org/10.1172/JCI136459.
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Research Article Pulmonology Vascular biology

Frataxin deficiency promotes endothelial senescence in pulmonary hypertension

Abstract

The dynamic regulation of endothelial pathophenotypes in pulmonary hypertension (PH) remains undefined. Cellular senescence is linked to PH with intracardiac shunts; however, its regulation across PH subtypes is unknown. Since endothelial deficiency of iron-sulfur (Fe-S) clusters is pathogenic in PH, we hypothesized that a Fe-S biogenesis protein, frataxin (FXN), controls endothelial senescence. An endothelial subpopulation in rodent and patient lungs across PH subtypes exhibited reduced FXN and elevated senescence. In vitro, hypoxic and inflammatory FXN deficiency abrogated activity of endothelial Fe-S–containing polymerases, promoting replication stress, DNA damage response, and senescence. This was also observed in stem cell–derived endothelial cells from Friedreich’s ataxia (FRDA), a genetic disease of FXN deficiency, ataxia, and cardiomyopathy, often with PH. In vivo, FXN deficiency–dependent senescence drove vessel inflammation, remodeling, and PH, whereas pharmacologic removal of senescent cells in Fxn-deficient rodents ameliorated PH. These data offer a model of endothelial biology in PH, where FXN deficiency generates a senescent endothelial subpopulation, promoting vascular inflammatory and proliferative signals in other cells to drive disease. These findings also establish an endothelial etiology for PH in FRDA and left heart disease and support therapeutic development of senolytic drugs, reversing effects of Fe-S deficiency across PH subtypes.

Authors

Miranda K. Culley, Jingsi Zhao, Yi Yin Tai, Ying Tang, Dror Perk, Vinny Negi, Qiujun Yu, Chen-Shan C. Woodcock, Adam Handen, Gil Speyer, Seungchan Kim, Yen-Chun Lai, Taijyu Satoh, Annie M.M. Watson, Yassmin Al Aaraj, John Sembrat, Mauricio Rojas, Dmitry Goncharov, Elena A. Goncharova, Omar F. Khan, Daniel G. Anderson, James E. Dahlman, Aditi U. Gurkar, Robert Lafyatis, Ahmed U. Fayyaz, Margaret M. Redfield, Mark T. Gladwin, Marlene Rabinovitch, Mingxia Gu, Thomas Bertero, Stephen Y. Chan

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Figure 8

FXN deficiency promotes endothelial senescence and worsens PH in vivo.

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FXN deficiency promotes endothelial senescence and worsens PH in vivo. (...
(A) Diagram of conditional endothelial-specific Fxn knockout mouse model. Experiments compare male Fxn flox/flox (Fxnf/f) control mice to mice expressing a tamoxifen-dependent Cdh5(PAC)-ERT2+-Cre recombinase (EC Fxn–/–) following chronic hypoxia exposure (3 weeks, 10% O2). (B) RT-qPCR of Fxn expression in CD31+ cells isolated from lungs (n = 6–7/group). (C) Confocal microscopic imaging and quantification of endothelial γH2AX (red signal represented by white arrows), α-SMA (green), and DAPI (blue) in lung tissue (n = 3/group). (D and E) Relative Cdkn2a and Tnf mRNA by RT-qPCR in CD31+ cells isolated from mouse lungs (n = 6–7/group). (F) Plasma IL-6 protein expression (n = 9 versus n = 7). (G) Measurement of immunofluorescent staining of vessel-associated Cd11b+ myeloid cells (orange), α-SMA (green), and DAPI (blue) in lung tissue (n = 5–6/group). (H) Picrosirius red staining in parallel versus orthogonal light with quantification of orthogonal signal representative of vessel collagen deposition (n = 4/group). (I) RVSP (mmHg) measured by right heart catheterization (n = 11 versus n = 7). (J) Fulton index (RV/LV+S, %) (n = 11 versus n = 7). (K) Pearson correlation between relative Fxn and Cdkn2a transcript levels (n = 18). (L) Pearson correlation between Cdkn2a expression and RVSP (n = 18). Scale bars: 50 μm. Two-tailed Student’s t test was performed with error bars that reflect mean ± SD.