MOTS-c Peptide Increases in Aging Muscle and May Help Maintain Muscle Quality
While blood levels of the mitochondrial peptide MOTS-c decrease with age, muscle levels increase 1.5-fold and are associated with better muscle quality in older men.
Quick Facts
What This Study Found
MOTS-c, a mitochondrial-derived peptide, shows opposite age-related patterns in blood versus muscle. Circulating MOTS-c in plasma decreased with age, but muscle MOTS-c expression was approximately 1.5 times higher in older (70–81 years) and middle-aged (45–55 years) men compared to young men (18–30 years).
The increase in muscle MOTS-c was associated with slow-type muscle fiber markers, consistent with the well-known fast-to-slow fiber type transition that occurs with aging. In older men, higher muscle MOTS-c was associated with better muscle quality (maximal leg-press strength relative to thigh cross-sectional area).
The study also found evidence that MOTS-c transcription may be regulated independently of the full-length 12S rRNA gene it sits within, and that its expression in human muscle is not linked to antioxidant response element (ARE) genes as previously seen in cell culture.
Key Numbers
3 age groups: young (18–30), middle-aged (45–55), older (70–81) · ~1.5-fold higher muscle MOTS-c in older/middle-aged vs young · Plasma MOTS-c decreased with age · Muscle MOTS-c correlated with muscle quality in older men
How They Did This
Cross-sectional study in healthy men across three age groups. Researchers measured MOTS-c levels in both blood plasma and skeletal muscle tissue, along with markers of muscle fiber type, muscle quality (leg press strength/thigh cross-sectional area), and gene expression using small RNA assays and transcriptome analysis.
Why This Research Matters
MOTS-c has been called an 'exercise mimetic' peptide and is being studied as a potential anti-aging molecule. This study provides the first detailed look at how MOTS-c behaves in actual human muscle tissue as people age. The finding that muscle MOTS-c increases with age — while blood levels decrease — suggests the peptide may play a compensatory protective role in aging muscle, potentially helping maintain muscle quality even as fiber types shift.
The Bigger Picture
Mitochondrial-derived peptides like MOTS-c and humanin are an emerging class of signaling molecules with potential anti-aging properties. This study is important because it shows that laboratory findings about MOTS-c don't always match what happens in human tissue — blood and muscle levels move in opposite directions, and cell culture gene expression patterns don't replicate in vivo. Understanding MOTS-c's true role in human aging requires studying actual human tissue, not just cell lines.
What This Study Doesn't Tell Us
Cross-sectional design — showing associations at a point in time, not causation over time. Small sample (specific n not stated). Only men were included. The study cannot determine whether increased muscle MOTS-c is protective or merely a byproduct of fiber type transition. Cell culture findings about MOTS-c and antioxidant genes did not replicate in human muscle, raising questions about translating in vitro MOTS-c research to humans.
Questions This Raises
- ?Is the increase in muscle MOTS-c with age a protective adaptation or simply a consequence of fiber type transition?
- ?Could supplemental MOTS-c improve muscle quality in older adults with sarcopenia?
- ?Why do plasma and muscle MOTS-c levels change in opposite directions with age — are they regulated by different mechanisms?
Trust & Context
- Key Stat:
- ~1.5× more MOTS-c in aging muscle Older and middle-aged men had approximately 50% higher MOTS-c in skeletal muscle than young men, associated with better muscle quality
- Evidence Grade:
- This is a cross-sectional observational study in human subjects — providing real-world data on MOTS-c in aging muscle tissue. The design shows associations but cannot establish causation, and the sample size appears modest.
- Study Age:
- Published in 2020, this study remains one of the few to examine MOTS-c levels in actual human skeletal muscle across age groups. The field of mitochondrial-derived peptides continues to grow rapidly.
- Original Title:
- Increased expression of the mitochondrial derived peptide, MOTS-c, in skeletal muscle of healthy aging men is associated with myofiber composition.
- Published In:
- Aging, 12(6), 5244-5258 (2020)
- Authors:
- D'Souza, Randall F, Woodhead, Jonathan S T(4), Hedges, Christopher P, Zeng, Nina, Wan, Junxiang, Kumagai, Hiroshi, Lee, Changhan, Cohen, Pinchas, Cameron-Smith, David, Mitchell, Cameron J, Merry, Troy L
- Database ID:
- RPEP-04743
Evidence Hierarchy
Watches what happens naturally without intervening.
What do these levels mean? →Frequently Asked Questions
What is MOTS-c and why does it matter for aging?
MOTS-c is a small peptide encoded by your mitochondrial DNA. It's been called an 'exercise mimetic' because it activates some of the same metabolic pathways as physical exercise, including AMPK activation and improved insulin sensitivity. This study shows it may also play a role in maintaining muscle quality as you age.
If MOTS-c increases in muscle with age, why do muscles still weaken?
The increase may be a compensatory response — the body producing more MOTS-c to help muscles cope with aging. But this natural increase may not be enough to fully prevent muscle decline. The association with better muscle quality in older men suggests MOTS-c is helpful, but other aging processes (inflammation, hormonal decline, reduced activity) may overwhelm its protective effects.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-04743APA
D'Souza, Randall F; Woodhead, Jonathan S T; Hedges, Christopher P; Zeng, Nina; Wan, Junxiang; Kumagai, Hiroshi; Lee, Changhan; Cohen, Pinchas; Cameron-Smith, David; Mitchell, Cameron J; Merry, Troy L. (2020). Increased expression of the mitochondrial derived peptide, MOTS-c, in skeletal muscle of healthy aging men is associated with myofiber composition.. Aging, 12(6), 5244-5258. https://doi.org/10.18632/aging.102944
MLA
D'Souza, Randall F, et al. "Increased expression of the mitochondrial derived peptide, MOTS-c, in skeletal muscle of healthy aging men is associated with myofiber composition.." Aging, 2020. https://doi.org/10.18632/aging.102944
RethinkPeptides
RethinkPeptides Research Database. "Increased expression of the mitochondrial derived peptide, M..." RPEP-04743. Retrieved from https://rethinkpeptides.com/research/d-souza-2020-increased-expression-of-the
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Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.