Inflammatory osteolysis is regulated by site-specific ISGylation of the scaffold protein NEMO
- Washington University School of Medicine, United States
Abstract
Inflammatory osteolysis is governed by exacerbated osteoclastogenesis. Ample evidence points to central role of NF-kB in such pathologic responses, yet the precise mechanisms underpinning specificity of these responses remain unclear. We propose that motifs of the scaffold protein IKKg/NEMO partly facilitate such functions. As proof-of-principle, we used site-specific mutagenesis to examine the role of NEMO in mediating RANKL-induced signaling in mouse bone marrow macrophages, known as osteoclast precursors. We identified lysine (K)270 as a target regulating RANKL signaling as K270A substitution results in exuberant osteoclastogenesis in vitro and murine inflammatory osteolysis in vivo. Mechanistically, we discovered that K270A mutation disrupts autophagy, stabilizes NEMO, and elevates inflammatory burden. Specifically, K270A directly or indirectly hinders binding of NEMO to ISG15, a ubiquitin-like protein, which we show targets the modified proteins to autophagy-mediated lysosomal degradation. Taken together, our findings suggest that NEMO serves as a toolkit to fine-tune specific signals in physiologic and pathologic conditions.
Data availability
The following datasets and raw data will be available on Dryad: Proteomics dataset, All Western blot raw data, FACS dataset microCT raw dataset. https://doi.org/10.5061/dryad.tx95x69tn
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Source Dateset: Inflammatory osteolysis is regulated by site-specific ISGylation of the scaffold protein NEMODryad Digital Repository, doi:10.5061/dryad.tx95x69tn.
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Author details
Funding
National Institutes of Health (AR049192)
- Yousef Abu-Amer
National Institutes of Health (AR068972)
- Gabriel Mbalaviele
National Institutes of Health (AR054326)
- Yousef Abu-Amer
National Institutes of Health (AR072623)
- Yousef Abu-Amer
National Institutes of Health (AR057235)
- Yousef Abu-Amer
Shriners Hospital For Children (86200)
- Yousef Abu-Amer
Shriners Hospital for Children (85160)
- Yousef Abu-Amer
National Institutes of Health (AR075860)
- Jie Shen
National Institutes of Health (AR077226)
- Jie Shen
National Institutes of Health (AR064755)
- Gabriel Mbalaviele
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All the animals were housed at the Washington University School of Medicine barrier facility. All experimental protocols were carried out in accordance with the ethical guidelines approved by the Washington University School of Medicine Institutional Animal Care and Use Committee (approval protocol #20190002).
Copyright
© 2020, Adapala et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Inflammatory osteolysis is regulated by site-specific ISGylation of the scaffold protein NEMO
eLife 9:e56095.
https://doi.org/10.7554/eLife.56095
