Skeletal muscle disuse during injury can lead to decreased muscle mass and function. While previous research has focused on gene expression changes associated with atrophy, the role of alternative splicing (AS) in response to unloading has not been well defined. This study aimed to explore the global changes in differential alternative splicing (DAS) in skeletal muscle following a period of immobilization.
In this primary research study published in Pflugers Archiv: European Journal of Physiology, twenty-one healthy males, aged approximately 26 years and weighing around 81 kg, underwent 14 days of unilateral knee-brace immobilization. The participants were assessed for strength and muscle mass before and after the immobilization period, and muscle biopsies from the vastus lateralis were taken pre-immobilization, as well as on days 3 and 14 of the study.
RNA sequencing was performed to identify DAS events using the rMATS package. The results indicated a significant decrease in leg strength, with a reduction of 21.5 kg (P < 0.0001), and a reduction in mid-thigh circumference of approximately 2% (P = 0.016). A total of 157,464 splicing events affecting 15,219 genes were identified on day 3, while 159,395 splicing events affecting 15,374 genes were identified on day 14. Notably, most DAS events occurred in coding sequence regions and were primarily attributed to exon skipping.
Interestingly, a higher number of DAS events were observed by day 14 compared to day 3, suggesting a time-dependent regulation of splicing events. Gene Ontology analysis of DAS at day 14 revealed 37 enriched biological processes related to MAPK signaling, mitochondrial function, and organelle organization. The study concluded that unloading-induced atrophy is associated with widespread changes in alternative splicing, particularly in genes linked to muscle maintenance and protein synthesis.
These findings suggest that alternative splicing may serve as a regulatory mechanism in muscle wasting during immobilization, highlighting the complexity of molecular responses to muscle disuse.
What this study does not show
This study does not establish a direct causal relationship between alternative splicing changes and specific health outcomes related to muscle function or recovery post-immobilization.
Evidence scorecard
- Analytic validity: Established
- Clinical validity: Not established
- Clinical utility: Not established