The skeletal muscle circadian clock regulates titin splicing through RBM20
- University of Florida, United States
- University of Vermont, United States
- University of Heidelberg, Germany
Abstract
Circadian rhythms are maintained by a cell autonomous, transcriptional-translational feedback loop known as the molecular clock. While previous research suggests a role of the molecular clock in regulating skeletal muscle structure and function, no mechanisms have connected the molecular clock to sarcomere filaments. Utilizing inducible, skeletal muscle specific, Bmal1 knockout (iMSBmal1-/-) mice, we showed that knocking out skeletal muscle clock function alters titin isoform expression using RNAseq, LC-MS, and SDS-VAGE. This alteration in titin's spring length resulted in sarcomere length heterogeneity. We demonstrate the direct link between altered titin splicing and sarcomere length in vitro using U7 snRNPs that truncate the region of titin altered in iMSBmal1-/- muscle. We identified a mechanism whereby the skeletal muscle clock regulates titin isoform expression through transcriptional regulation of Rbm20, a potent splicing regulator of titin. Lastly, we used an environmental model of circadian rhythm disruption and identified significant down-regulation of Rbm20 expression. Our findings demonstrate the importance of the skeletal muscle circadian clock in maintaining titin isoform through regulation of RBM20 expression. Because circadian rhythm disruption is a feature of many chronic diseases, our results highlight a novel pathway that could be targeted to maintain skeletal muscle structure and function in a range of pathologies.
Data availability
Sequencing data have been deposited in GEO under accession code: GSE189865
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The Skeletal Muscle Molecular Clock Regulates Sarcomere Length Through Titin SplicingNCBI Gene Exression Omnibus, GSE189865.
Article and author information
Author details
Christopher A Wolff
Funding
NIH Office of the Director (DP5OD017865)
- Eric T Wang
National Institute of Arthritis and Musculoskeletal and Skin Diseases (R01AR066082,F31AR070625)
- Karyn A Esser
National Heart Lung and Blood Institute (R01HL157487)
- Michael J Previs
Fondation Leducq (13CVD04)
- David W Hammers
- Siegfried Labeit
The authors declare that the funders had no impact on the design or data collection or writing of this manuscript
Ethics
Animal experimentation: All experiments were conducted in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and approved and monitored by the University of Florida Institutional Animal Care and Use Committee Protocols (IACUC numbers: 201809136, IACUC202100000018).
Copyright
© 2022, Riley 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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