Background <p>Skeletal muscle is a central regulator of insulin sensitivity and glucose homeostasis. The ryanodine receptor 1 (RYR1) is highly expressed in skeletal muscle and plays a key role in myogenic differentiation. We hypothesize that RYR1<sup>+</sup> extracellular vesicles (EVs) represent a skeletal muscle-derived EV subpopulation whose abundance and small RNA (smRNA) cargo are associated with aging, insulin action, and exercise responsiveness.</p> Methods <p>We tested this hypothesis through in vitro analyses of smRNAs of skeletal muscle-derived EVs and in vivo evaluation of their exercise responsiveness and association with insulin action in older adults. Using an integrated workflow combining centrifugation, polymer-based precipitation, and single-EV sorting, we isolated RYR1<sup>+</sup> and RYR<sup>−</sup> EVs secreted from myobundles—3D contractile skeletal muscle tissues engineered from primary muscle progenitor cells obtained from healthy donors (<i>n</i> = 6). We also isolated plasma EVs from 48 human participants and performed targeted high-resolution flow cytometry to evaluate EV biomarkers associated with aging, insulin action, and exercise responsiveness in older adults.</p> Results <p>By smRNA sequencing, compared to myobundle RYR<sup>−</sup> EVs, RYR1<sup>+</sup> EVs contained three unique microRNAs (miRNAs) and an additional 21 miRNAs with significantly greater abundance (including canonical myoMiRs miR-206, miR-1-3p, and miR-208a-3p). Of the 24 RYR1<sup>+</sup> EV-enriched miRNAs, experimentally-supported mRNA targets (<i>n</i> = 422) are involved in pathways governing cell proliferation, apoptosis, senescence, insulin and glucose signaling. In two independent cohorts, including older adults with prediabetes or unknown prediabetes status, frequencies of RYR1<sup>+</sup> EV subsets were significantly upregulated by chronic exercise with greater RYR1<sup>+</sup> EV frequencies associated with better insulin action.</p> Conclusions <p>These complementary in vitro and in vivo data identify skeletal muscle-derived RYR1<sup>+</sup> EVs as upregulated by exercise and as carriers of miRNAs linked to insulin action in older adults, including those with prediabetes. These results highlight skeletal muscle-derived EVs as novel biomarkers and potential mediators of systemic metabolic regulation and healthy aging.</p> Graphical Abstract <p></p>

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RYR1+ skeletal muscle-derived extracellular vesicles are exercise responsive and associated with insulin action

  • Xin Zhang,
  • Christopher G. Vann,
  • David B. Bartlett,
  • Alastair Khodabukus,
  • George A. Truskey,
  • Nenad Bursac,
  • Joseph A. Houmard,
  • Johanna L. Johnson,
  • Kim M. Huffman,
  • Brian J. Andonian,
  • William E. Kraus,
  • Virginia Byers Kraus

摘要

Background

Skeletal muscle is a central regulator of insulin sensitivity and glucose homeostasis. The ryanodine receptor 1 (RYR1) is highly expressed in skeletal muscle and plays a key role in myogenic differentiation. We hypothesize that RYR1+ extracellular vesicles (EVs) represent a skeletal muscle-derived EV subpopulation whose abundance and small RNA (smRNA) cargo are associated with aging, insulin action, and exercise responsiveness.

Methods

We tested this hypothesis through in vitro analyses of smRNAs of skeletal muscle-derived EVs and in vivo evaluation of their exercise responsiveness and association with insulin action in older adults. Using an integrated workflow combining centrifugation, polymer-based precipitation, and single-EV sorting, we isolated RYR1+ and RYR EVs secreted from myobundles—3D contractile skeletal muscle tissues engineered from primary muscle progenitor cells obtained from healthy donors (n = 6). We also isolated plasma EVs from 48 human participants and performed targeted high-resolution flow cytometry to evaluate EV biomarkers associated with aging, insulin action, and exercise responsiveness in older adults.

Results

By smRNA sequencing, compared to myobundle RYR EVs, RYR1+ EVs contained three unique microRNAs (miRNAs) and an additional 21 miRNAs with significantly greater abundance (including canonical myoMiRs miR-206, miR-1-3p, and miR-208a-3p). Of the 24 RYR1+ EV-enriched miRNAs, experimentally-supported mRNA targets (n = 422) are involved in pathways governing cell proliferation, apoptosis, senescence, insulin and glucose signaling. In two independent cohorts, including older adults with prediabetes or unknown prediabetes status, frequencies of RYR1+ EV subsets were significantly upregulated by chronic exercise with greater RYR1+ EV frequencies associated with better insulin action.

Conclusions

These complementary in vitro and in vivo data identify skeletal muscle-derived RYR1+ EVs as upregulated by exercise and as carriers of miRNAs linked to insulin action in older adults, including those with prediabetes. These results highlight skeletal muscle-derived EVs as novel biomarkers and potential mediators of systemic metabolic regulation and healthy aging.

Graphical Abstract