MOTS-c research: what the published studies show

Identity, and Where the Gene Sits

MOTS-c is a 16-amino-acid peptide encoded by a short open reading frame in the mitochondrial 12S rRNA gene, and its name stands for mitochondrial open reading frame of the 12S rRNA-c.^[1] The discovery followed the earlier identification of a short reading frame in mitochondrial DNA encoding humanin, which the same paper cites as the precedent for looking.^[1]

Humanin is a separate peptide from a separate reading frame and is sold separately on this site. No humanin result appears on this page as a MOTS-c result, and where a cited paper reports both, the two are reported apart.

The Discovery Paper, Which Is Mouse and Cell Work

Reference 1 reports that the peptide regulates insulin sensitivity and metabolic homeostasis, and that its primary target organ appears to be skeletal muscle.^[1] The hedge is the authors'.^[1] At the cellular level the described actions inhibit the folate cycle and the de novo purine biosynthesis tethered to it, leading to AMPK activation.^[1]

In mice, giving MOTS-c prevented age-dependent and high-fat-diet-induced insulin resistance, and prevented diet-induced obesity.^[1] The paper's own conclusion is that mitochondria may actively regulate metabolic homeostasis using peptides encoded within their genome.^[1] Both hedges are carried here because both are in the abstract.

Cell Metabolism published a Preview alongside it, by Kim Zarse and Michael Ristow.^[6] It is favorable commentary rather than primary work and no result is drawn from it here.^[6] It is cited because it is on the record beside reference 1, and because it introduces a framing reference 1's own abstract does not use: that the peptide promotes biosynthesis of AICAR, an endogenous AMP analogue, which then activates AMPK.^[6] AICAR is a separate product on this site. Nothing from its literature belongs on this page, and nothing from this page belongs on its. A cell making an AMP analogue internally is not the same event as supplying that analogue.

The 2021 Mouse Work, and the Human Half of the Same Paper

MOTS-c significantly enhanced physical performance in mice at 2, 12 and 22 months of age.^[2] The paper reports regulation of nuclear genes related to metabolism and proteostasis, effects on skeletal muscle metabolism, and effects on myoblast adaptation to metabolic stress.^[2] Late-life administration increased physical capacity and healthspan in mice.^[2]The human part of that paper is narrower than the mouse part and it is worth stating exactly.^[2] In humans, exercise induced endogenous MOTS-c expression in skeletal muscle and in circulation, which is a measurement of the peptide the body makes under an exercise stimulus.^[2] Nobody was given MOTS-c.

Acute Exercise in People, Where the Two Peptides Part Company

Thirty subjects were randomized to endurance exercise, resistance exercise, or control, with muscle biopsies and blood taken before and after.^[3] Gene expression responded as expected for each exercise mode.^[3]

Now the peptide results: circulating humanin was significantly elevated by acute endurance exercise but not by resistance exercise.^[3] MOTS-c showed only a trend to increase after endurance exercise.^[3] Plasma levels of both were not correlated with maximal oxygen uptake, leg strength or muscle mitochondrial DNA copy number.^[3] At rest, humanin correlated positively with MOTS-c and with age.^[3]

The paper's own summary says acute endurance exercise stimulates these peptides in particular humanin.^[3] Read the title alone and this looks like support for MOTS-c. Read the result and it is mostly not.

Sixteen Weeks of Exercise, and a Result That Split by Group

A secondary analysis of a 16-week aerobic and resistance exercise intervention measured MOTS-c in 25 Hispanic and 24 non-Hispanic White breast cancer survivors.^[4] Participants were randomized to exercise or standard care, and the two groups differed at baseline in age, adiposity, disease stage and metabolic profile.^[4]

MOTS-c rose significantly against both baseline and usual care in the non-Hispanic White group.^[4] It did not rise in the Hispanic group.^[4] In the group where it rose, the post-exercise level was associated with reductions in fat mass, body weight, HOMA-IR and CRP and with an increase in lean mass.^[4]

The authors frame the split as possibly reflecting ethnic-specific mitochondrial DNA variation.^[4] Whatever the reason, the plain reading is that the same intervention moved this peptide in one group and not the other.

The Longevity Claim, and Where It Comes From

Reference 5 is a three-page piece in Aging Cell rather than a study, indexed by PubMed as an article-commentary, and it concerns the m.1382A>C polymorphism in the MOTS-c coding region, specific to a Northeast Asian population.^[5] The authors propose that it may be among the putative mechanisms behind high longevity in Japan.^[5] Its own text says more research is needed.^[5]

That sentence is the origin of most longevity language attached to this peptide.^[5] It is a hypothesis with a hedge in it, and it is cited here so the page can say so rather than inherit the framing.

State of the Evidence

A phrase search for MOTS-c returns roughly 650 indexed records, of which about 180 carry the compound in the title. Six are cited here, of which four are primary studies.

Nobody has given this peptide to a person in a published study.^[1][2][3][4] Every human measurement above is of endogenous peptide, and in each case the intervention was exercise. Filtering the literature by trial publication type returns a small set, and every record in it measures the peptide rather than administering it; the interventions in those studies are exercise, heat stress, metformin, caffeine and beetroot juice. The interventional evidence for MOTS-c itself is entirely mouse and cell work at references 1 and 2.

The two human exercise studies did not produce clean results.^[3][4] One found a trend rather than a significant rise, in a paper whose significant rise belonged to a different peptide.^[3] The other found a rise in one ethnic group and not the other, in a secondary analysis of groups that differed at baseline.^[4]

Authorship on this page is more concentrated than on any other product in this family, and there is no independent primary source.^[1][2][3][4] Pinchas Cohen is an author of all four primary studies. Junxiang Wan is an author of references 1, 3 and 4. Su-Jeong Kim is an author of references 1 and 4. Changhan Lee, the discovery paper's first author, is also an author of reference 2.

That matters because of what it means for the two weaker human results.^[3][4] They are not outside checks on the discovery group's claims, they carry that group's co-authors too. The only source on this page with no shared authorship is reference 5, and reference 5 is a commentary rather than data. Nothing here is extrapolated from Humanin. Humanin is sold separately on this site and comes from a different reading frame in the same genome. Reference 3 is the clearest demonstration on this page that the two behave differently in the same experiment.