Poster abstracts
Poster number 4 submitted by Alexander Ahn
Alternative RNA Splicing in Skeletal Muscle from Exercise, Rapamycin, and Aging.
Alexander Ahn (School of Kinesiology, University of Michigan), Jeongjin J. Kim (School of Kinesiology, University of Michigan), Aaron L. Slusher (School of Medicine, Yale University), Richard A. Miller (Department of Pathology-Michigan Medicine, University of Michigan), Andrew T. Ludlow (School of Kinesiology, University of Michigan)
Abstract:
RNA splicing is a highly conserved post-transcriptional mechanism, defined as a new hallmark of aging[1]. While alternative splicing (AS) generates multiple mRNA variants to diversify the proteome[2], exercise-induced stress appears to transiently perturb AS in skeletal muscle (SkM)[3]. However, role of AS in exercise as part of healthy aging is not determined. This study aimed to better understand differential AS in SkM from publicly accessible short-read RNA-Seq (SRS) data compared to single-molecule long-read (LRS). First, SRS data from exercise studies were extracted from the Gene Expression Omnibus[4,5] and differential AS based on the detection of exon-exon junctions were examined, in which exon-skipping was the most common. Subsequently, we performed LRS on acutely exercised and lifelong rapamycin-treated sedentary mice as comparable models to the SRS. Differential AS events were overlapped with the SRS and LRS data sets and candidate genes were enriched via GO analyses: 1,038 genes with splice-switching events were detected 1h post-exercise in our rodent model using LRS; of 2,347 genes with splicing changes, 351 (15%) overlapped between active/endurance trained elders (AET) and sedentary youths from SRS; GO analyses of genes with splicing changes illustrated significant enrichment in the mitochondrion and ATP-binding functions. However, AET and rapamycin lacked similarities in differential gene expression. To conclude, this study reaffirmed previous studies that exercise changes SkM transcriptome. While SRS is a powerful tool for identifying differentially expressed genes, it lacks AS detection. As such, “hidden” genes with no transcriptional but significant AS and protein expression rewiring pose a major gap in knowledge; our preliminary data support how LRS technologies can overcome such barriers. Additionally, our data indicate that while AET and lifelong rapamycin treatment both promote healthy SkM aging, they may act via different regulatory mechanisms.
References:
1. Bhadra, M. et al. (2020). Alternative splicing in aging and longevity. Human genetics, 139, 357-369.
2. Aebersold, R. et al. (2018). How many human proteoforms are there? Nature chemical biology, 14(3), 206-214.
3. Sharp, L. et al. (2019). Endurance exercise leads to beneficial molecular and physiological effects in a mouse model of myotonic dystrophy type 1. Muscle & nerve, 60(6), 779-789.
4. Pattamaprapanont, P. et al. (2016). Muscle contraction induces acute hydroxymethylation of the exercise-responsive gene Nr4a3. Frontiers in endocrinology, 7, 165.
5. Rubenstein, A. B. et al. (2022). Skeletal muscle transcriptome response to a bout of endurance exercise in physically active and sedentary older adults. American Journal of Physiology-Endocrinology and Metabolism, 322(3), E260-E277.
Keywords: Alternative RNA Splicing, Skeletal Muscle, Aging