MOTS-c

MOTS-c (mitochondrial open reading frame of the twelve S rRNA type-c) is a 16-amino-acid peptide encoded by a short open reading frame located within the mitochondrial 12S ribosomal RNA gene rather than in nuclear DNA, and it belongs to a small class of molecules known as mitochondrial-derived peptides. It was first described in 2015 and has been studied since then almost entirely in cultured cells, rodents, and human observational samples.

This page summarises the published record: the peptide's genomic origin, the mechanism its discoverers proposed, the study models used, and where the evidence is thin or conflicting. It contains no use, dosing or administration guidance. Material is supplied under our research use policy for laboratory research only.

Specifications

Genomic origin and discovery

Lee et al. (2015), in Cell Metabolism, reported the identification of MOTS-c as the product of a short open reading frame nested inside the mitochondrial 12S rRNA gene. It sits alongside humanin among the few peptides encoded by the mitochondrial rather than the nuclear genome. The finding implies that the 16.6 kb mitochondrial genome carries coding capacity beyond the thirteen oxidative phosphorylation subunits, two rRNAs and twenty-two tRNAs it was long understood to encode.

Reported mechanism: the folate-AICAR-AMPK axis

The mechanism proposed by Lee et al. (2015) is indirect rather than receptor-mediated. In their in vitro and murine experiments, MOTS-c inhibited the folate one-carbon cycle at the level of 5-methyltetrahydrofolate, a pathway required for de novo purine synthesis. Blocking that step caused accumulation of 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an established activator of AMP-activated protein kinase. AMPK activation therefore occurred through metabolite accumulation rather than through the canonical AMP/ATP ratio. Wan et al. (2023), reviewing the field in the Journal of Translational Medicine, describe this folate-AICAR-AMPK pathway as the principal mechanism reported to date.

Nuclear translocation

Kim et al. (2018), in Cell Metabolism, reported a separate behaviour. In cultured cells subjected to metabolic stress — glucose restriction, serum deprivation or oxidative stress — MOTS-c was observed to translocate to the nucleus within approximately thirty minutes, in an AMPK-dependent manner. Once nuclear, it was reported to associate with promoters carrying antioxidant response elements and to interact with stress-responsive transcription factors including NRF2, which the authors framed as evidence that mitochondrial-to-nuclear signalling is genetically encoded. This work was conducted in cell culture.

No cell-surface receptor has been established

One gap is worth stating plainly. Unlike peptides with defined receptor pharmacology, MOTS-c has no confirmed cell-surface receptor in the published literature. Wan et al. (2023) leave several mechanistic questions open, including how MOTS-c transcripts are exported from the mitochondrion and how the peptide regulates nuclear gene expression once there. How circulating MOTS-c enters target cells, and how it is cleared in vivo, are equally unsettled. Descriptions of MOTS-c as acting on a specific named receptor are not supported by the record.

Exercise responsiveness and human observational data

Reynolds et al. (2021), in Nature Communications, examined MOTS-c in mice at 2, 12 and 22 months of age. The peptide was administered to the animals, and the authors reported differences in treadmill running performance between treated and untreated mice, together with regulation of nuclear genes related to metabolism and proteostasis in skeletal muscle. These are rodent results.

The same paper included a separate human component in which sedentary healthy young male volunteers exercised on a stationary bicycle and endogenous MOTS-c was measured. Relative to pre-exercise values, skeletal muscle MOTS-c rose approximately 11.9-fold by Western blot, while circulating MOTS-c rose approximately 1.6-fold during and 1.5-fold after exercise by ELISA, returning toward baseline within four hours. This was a small volunteer sample, and no compound was administered to the human subjects.

A further human dataset is cross-sectional. Ramanjaneya et al. (2019), in Frontiers in Endocrinology, measured circulating mitochondrial-derived peptides across 225 subjects and reported serum MOTS-c significantly lower in subjects with poorly controlled type 2 diabetes than in healthy controls, with negative correlations to HbA1c and glucose. An association measured at one time point does not establish causation.

Genetic data on the sequence are mixed

The mitochondrial variant m.1382A>C, largely restricted to Northeast Asian populations, produces a Lys14Gln substitution in the MOTS-c sequence. Zempo et al. (2021), in Aging, reported a meta-analysis of three cohorts totalling 27,527 subjects in which males carrying the C allele showed a higher prevalence of type 2 diabetes while females did not, and reported reduced activity of the K14Q form relative to the native sequence in cell-based assays. Interpretation of this variant has shifted as sample sizes have grown; its significance should be treated as unsettled.

Other preclinical models

Ming et al. (2016), in Biochemical and Biophysical Research Communications, reported on MOTS-c in ovariectomised mice, a rodent model used to study post-menopausal bone loss. They reported that RANKL-induced osteoclast differentiation was inhibited and that phosphorylated AMPK levels increased; compound C, an AMPK inhibitor, partially abrogated the effect on osteoclastogenesis, which they read as evidence of AMPK dependence. This is a rodent study, and no corresponding human data exist.

Clinical development status

CB4211, described by Miller et al. (2022) as a MOTS-c analogue, is the only compound of this class recorded in a clinical trial registry. CohBar, Inc. registered a Phase 1a/1b protocol (ClinicalTrials.gov NCT03998514) with portions in healthy non-obese adults and in adults with non-alcoholic fatty liver disease. Its registered primary outcome measures were adverse events, clinical laboratory evaluations, vital signs and electrocardiogram parameters — safety and tolerability measures, not efficacy measures. The registry lists the study as completed in April 2021 with 88 participants enrolled, and no results have been posted to it.

No MOTS-c peptide or analogue has completed a Phase 2 or Phase 3 efficacy trial or received marketing approval from the FDA or any comparable regulator. No human efficacy conclusions about MOTS-c can be drawn from the current literature.

Analytical considerations

Identity is normally confirmed by electrospray mass spectrometry against the expected average mass of approximately 2174.6 Da, and purity by reversed-phase HPLC with the gradient and detection wavelength stated on the chromatogram. One distinction matters when comparing supplier paperwork: gross peptide mass is not net peptide content, since a vial also holds counterion, residual water and any excipient. A certificate reporting HPLC purity but omitting net peptide content has answered half the question. Our lab testing page walks through reading each document independently.

Handling and stability

The MOTS-c sequence contains no cysteine, so disulfide scrambling is not a failure mode. It does contain two methionine residues and one tryptophan, all susceptible to oxidation, which is why amber vials or foil wrapping and exclusion of headspace oxygen are standard practice for this peptide in both solid and solution form. Lyophilised material held at minus 20 degrees C and desiccated is substantially more stable than the same material in solution, where hydrolysis, oxidation and aggregation proceed far faster. Cold-chain and container practice is collected under storage; bringing lyophilised material into solution without shear or foaming is covered in reconstitution, and the concentration calculator handles the mass-to-volume arithmetic.

Regulatory status

MOTS-c is not an FDA-approved drug. It has not been approved to treat, prevent, cure or mitigate any disease or condition, and it is not a dietary supplement ingredient. Material offered here is for laboratory research use only, is not for human or animal consumption, and is not supplied for diagnostic or therapeutic purposes. Full terms are set out in the research use policy.

How should lyophilised MOTS-c be stored?

Lyophilised peptide is conventionally held at minus 20 degrees C or below, desiccated and protected from light. Because of the two methionine residues and the tryptophan, light and oxygen exposure are the relevant degradation risks alongside temperature.

Why does a vial labelled with a given mass contain less peptide than that?

Lyophilised peptide includes counterion (commonly trifluoroacetate), residual water and any excipient in addition to the peptide itself. The peptide fraction is reported as net peptide content, determined by amino acid analysis or nitrogen determination, and is a separate figure from HPLC purity.

What should a certificate of analysis for MOTS-c contain?

An RP-HPLC purity chromatogram with the method stated, mass spectrometric identity confirmation against the expected mass, net peptide content, the counterion, water content, and a lot number matching the vial. Third-party results carry more weight than in-house ones; see lab testing.

Has MOTS-c been approved by any regulator?

No. No MOTS-c peptide or analogue has received marketing approval. Registered clinical work to date has been limited to a Phase 1 safety and pharmacokinetic study of a synthetic analogue.

References

• Lee C, Zeng J, Drew BG, et al. (2015). The Mitochondrial-Derived Peptide MOTS-c Promotes Metabolic Homeostasis and Reduces Obesity and Insulin Resistance. Cell Metabolism.
• Ming W, Lu G, Xin S, et al. (2016). Mitochondria related peptide MOTS-c suppresses ovariectomy-induced bone loss via AMPK activation. Biochemical and Biophysical Research Communications.
• Kim KH, Son JM, Benayoun BA, Lee C. (2018). The Mitochondrial-Encoded Peptide MOTS-c Translocates to the Nucleus to Regulate Nuclear Gene Expression in Response to Metabolic Stress. Cell Metabolism.
• Ramanjaneya M, Bettahi I, Jerobin J, et al. (2019). Mitochondrial-Derived Peptides Are Down Regulated in Diabetes Subjects. Frontiers in Endocrinology.
• Zempo H, Kim SJ, Fuku N, et al. (2021). A pro-diabetogenic mtDNA polymorphism in the mitochondrial-derived peptide, MOTS-c. Aging.
• Reynolds JC, Lai RW, Woodhead JST, et al. (2021). MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nature Communications.
• Miller B, Kim SJ, Kumagai H, Yen K, Cohen P. (2022). Mitochondria-derived peptides in aging and healthspan. Journal of Clinical Investigation.
• Wan W, Zhang L, Lin Y, et al. (2023). Mitochondria-derived peptide MOTS-c: effects and mechanisms related to stress, metabolism and aging. Journal of Translational Medicine.