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Altered relaxation and Mitochondria-Endoplasmic Reticulum Contacts Precede Major (Mal)adaptations in Aging Skeletal
Ryan J Allen1, Ana Kronemberger1, Qian Shi2
1Department of Health and Human Physiology, Fraternal Order of Eagles Diabetes Research Center, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA, USA.
Biorxiv : the Preprint Server for Biology
|February 20, 2025
Summary
Aging slows muscle relaxation and alters mitochondria-ER contacts (MERCs) before force loss. Regular exercise preserves muscle relaxation and MERC structure, suggesting new therapeutic targets for age-related muscle dysfunction.
Area of Science:
- Muscle physiology
- Cellular biology
- Aging research
Background:
- Sarcopenia, or age-related muscle dysfunction, increases morbidity and mortality.
- Cellular changes preceding sarcopenia, particularly at mitochondria-ER contacts (MERCs), are poorly understood.
- MERCs are crucial for muscle tension generation, involving mitochondria and the sarcoplasmic reticulum.
Purpose of the Study:
- To investigate early cellular changes in aging muscle, focusing on MERCs.
- To determine if MERC ultrastructure and proteome are altered during aging.
- To assess the impact of exercise on aging-related MERC changes and muscle function.
Main Methods:
- Comparative study of young adult and older mice.
- Analysis of muscle relaxation rate and excitation-contraction-relaxation (ECR) cycles.
- Evaluation of MERC ultrastructure and mitochondria-associated ER membrane (MAM) protein composition.
- Assessment of exercise effects on muscle function and MERC integrity.
Main Results:
- Aging slows muscle relaxation and lengthens ECR cycles before significant force decline or fiber type switching.
- MERC ultrastructure and MAM protein composition are altered early in aging, correlating with impaired muscle relaxation.
- Regular exercise maintains muscle relaxation rate and MERC ultrastructure in aging mice.
- A set of MAM proteins involved in key cellular processes are inversely regulated by aging and exercise.
Conclusions:
- Early aging affects muscle relaxation and MERC integrity before major sarcopenia hallmarks appear.
- MERC alterations are closely linked to age-related muscle relaxation deficits.
- Exercise interventions can preserve muscle relaxation and MERC structure during aging.
- Specific MAM proteins represent potential therapeutic targets for mitigating age-related muscle dysfunction.
Keywords:
agingendoplasmic reticulumexercisemitochondriamitochondrial-associated ER membranessarcopeniasarcoplasmic reticulumskeletal muscleMore Related Videos
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