Human embryonic stem (hES) cells are highly sensitive to apoptotic stimuli such as DNA damage, which allows for the rapid elimination of mutated cells during development. However, the mechanisms that maintain hES cells in the primed apoptotic state are not completely known. Key activators of apoptosis, the BH3-only proteins, are present at low levels in most cell types. In contrast, hES cells have constitutive high levels of the BH3-only protein, NOXA. We examined the importance of NOXA for enabling apoptosis in hES cells. hES cells deleted for NOXA showed remarkable protection against multiple apoptotic stimuli. NOXA was constitutively localized to the mitochondria, where it interacted with MCL1. Strikingly, inhibition of MCL1 in NOXA knockout cells was sufficient to sensitize these cells to DNA damage-induced cell death. Our study demonstrates that an essential function of constitutive high levels of NOXA in hES cells is to effectively antagonize MCL1 to permit rapid apoptosis.
Bibliographical notePublisher Copyright:
© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For permissions, please email: email@example.com.
We thank the Deshmukh lab members for their discussions and critical review of this work. We also thank Dr. Anirban Kar, Dr. Ayumi Nakamura and Dr. Vijay Swahari for reviewing the manuscript.
The Neuroscience Microscopy Core Facility, supported, in part, by funding from the National Institutes of Health - National Institute of Neurological Disease and Stroke Neuroscience Center Support Grant P30 NS045892 and the National Institutes of Health - National Institute of Child Health and Human Development Intellectual and Developmental Disabilities Research Center Support Grant U54 HD079124. This work was supported by National Institutes of Health grant GM118331 to M.D.
R.B.: conception and design, collection and assembly of data, data analysis and interpretation, manuscript writing; S.K., E.H.: collection and assembly of data, data analysis and interpretation; N.K.: data analysis; A.B.: contributed in CRISPR knockout generation; N.M.M.: contributed in Western blot experiments; M.D.: conception and design, financial support, administrative support, manuscript writing, and final approval of the manuscript.
Data Availability StatementNo new data were generated or analyzed in support of this research.
- cell death
- DNA damage
- human embryonic stem cells