Phosphoproteomic mapping reveals distinct signaling actions and activation of muscle protein synthesis by Isthmin-1
- Stanford University, United States
- Duke University, United States
Abstract
The secreted protein Isthmin-1 (Ism1) mitigates diabetes by increasing adipocyte and skeletal muscle glucose uptake by activating the PI3K-Akt pathway. However, while both Ism1 and insulin converge on these common targets, Ism1 has distinct cellular actions suggesting divergence in downstream intracellular signaling pathways. To understand the biological complexity of Ism1 signaling, we performed phosphoproteomic analysis after acute exposure, revealing overlapping and distinct pathways of Ism1 and insulin. We identify a 53 % overlap between Ism1 and insulin signaling and Ism1-mediated phosphoproteome-wide alterations in ~ 450 proteins that are not shared with insulin. Interestingly, we find several unknown phosphorylation sites on proteins related to protein translation, mTOR pathway and, unexpectedly, muscle function in the Ism1 signaling network. Physiologically, Ism1 ablation in mice results in altered proteostasis, including lower muscle protein levels under fed and fasted conditions, reduced amino acid incorporation into proteins, and reduced phosphorylation of the key protein synthesis effectors Akt and downstream mTORC1 targets. As metabolic disorders such as diabetes are associated with accelerated loss of skeletal muscle protein content, these studies define a non-canonical mechanism by which this anti-diabetic circulating protein controls muscle biology.
Data availability
The phosphoproteomics dataset has been deposited to ProteomeXchange Consortium through JPost PXD031719 (JPST001484)(Okuda et al., 2017). The code for all analysis related to phosphoproteomic data is available at https://github.com/Svensson-Lab/Isthmin-1/tree/F442A_phosphoproteomics. The single-cell RNA sequencing data was re-analyzed from a previously published dataset (Baht et al., 2020). All the other data generated or analyzed in this study are included in the manuscript and supporting files.
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Single Cell RNAseq on whole muscle one day after injury and uninjured controlNCBI Gene Expression Omnibus GSE145236.
Article and author information
Author details
Ewa Bielczyk-Maczynska
Capucine Van Rechem
Funding
National Institute of Diabetes and Digestive and Kidney Diseases (DK125260)
- Katrin J Svensson
National Institute of Diabetes and Digestive and Kidney Diseases (DK111916)
- Katrin J Svensson
American Heart Association (905674)
- Meng Zhao
American Heart Association (18POST34030448)
- Ewa Bielczyk-Maczynska
National Heart, Lung, and Blood Institute (T32HL007057)
- David E Lee
American Heart Association (882082)
- Nickeisha Cuthbert
National Institute of Diabetes and Digestive and Kidney Diseases (DK116074)
- Katrin J Svensson
National Institute on Aging (R21AG065943)
- James P White
NIH Office of the Director (K01AG05666)
- James P White
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Animal experiments were performed per procedures approved by the Institutional Animal Care and Use Committee of the Stanford Animal Care and Use Committee (APLAC) protocol number #32982.
Copyright
© 2022, Zhao 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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Phosphoproteomic mapping reveals distinct signaling actions and activation of muscle protein synthesis by Isthmin-1
eLife 11:e80014.
https://doi.org/10.7554/eLife.80014
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