MOTS-c and the mitochondrial peptides: what is known and where the evidence ends

A gene inside a gene

For decades mitochondrial DNA was thought to encode only 13 respiratory-chain proteins, ribosomal RNAs and transfer RNAs. In 2001 a Japanese group identified humanin, a short peptide that, in cultured cells, protected against neuronal death induced by familial Alzheimer's genes and β-amyloid². Six small humanin-like peptides (SHLPs) were later described, encoded in the same 16S ribosomal RNA region; SHLP2 and SHLP3 reduced apoptosis in vitro, and circulating SHLP2 declined with age³.

In 2015, University of Southern California researchers described MOTS-c (mitochondrial open reading frame of the 12S rRNA-c): a 16-amino-acid peptide encoded within the 12S ribosomal RNA gene¹. Together these compounds form the mitochondrial-derived peptide family, signals the mitochondrion sends to the rest of the cell and the body. The specifications of the peptide we supply for research are on the MOTS-c page.

What the mice showed

In the original study the main target organ appeared to be skeletal muscle. In cells, MOTS-c inhibited the folate cycle and de novo purine synthesis, leading to AMPK activation. In mice, treatment prevented age-related and high-fat-diet insulin resistance as well as diet-induced obesity¹.

In 2021 the same group showed that MOTS-c improved physical performance in young (2 months), middle-aged (12 months) and old (22 months) mice. In a protocol started late in life, at 23.5 months, with intermittent dosing 3 times a week, treatment was associated with greater physical capacity and healthspan⁵. That is why it is described as an "exercise mimetic", although the term is an interpretation, not a clinical result.

From the mitochondrion to the nucleus

A 2018 finding changed how the peptide is understood: under metabolic stress, MOTS-c translocates to the nucleus in an AMPK-dependent manner and regulates a broad set of genes, including those with antioxidant response elements, and interacts with transcription factors such as NRF2⁴. It is one of the first demonstrations that a mitochondrially encoded factor regulates the nuclear genome.

Which receptor or protein recognizes MOTS-c is still an open question. In 2024 a study proposed the kinase CK2 as a direct target: MOTS-c bound and activated CK2 in cell-free systems, and inhibiting CK2 blunted the prevention of muscle atrophy and the increase in glucose uptake in mice⁶. It is an important step, not yet independently replicated.

What has been measured in humans

Human data, for now, do not include administration of the native peptide. In the 2021 work, exercise induced endogenous MOTS-c expression in skeletal muscle and in the circulation⁵. In a study in Sweden, 30 subjects were randomized to endurance exercise, resistance exercise or control (10 per group); in the 45-minute cycling group, circulating humanin rose significantly, while MOTS-c showed only a trend to increase¹⁰.

In a cross-sectional study of 225 people in Qatar, serum MOTS-c was lower in type 2 diabetes than in controls and correlated negatively with age, HbA1c and glucose⁹. These are associations: they do not show whether low peptide is a cause or a consequence of the metabolic disorder.

The Japanese variant: longevity and diabetes

In 2015 a Japanese and Spanish group proposed that the m.1382A>C polymorphism, specific to Northeast Asian populations and located in the MOTS-c gene, might be among the mechanisms behind Japanese longevity; the authors stated that more research was needed⁷.

In 2021 its functional effect was described: the variant causes an amino-acid change (K14Q) in the peptide. In a meta-analysis of three cohorts with 27,527 people, male carriers of the C allele had a higher prevalence of type 2 diabetes, but not females; in one cohort the increase was limited to the least physically active men. In fat-fed mice, MOTS-c reduced weight and improved glucose tolerance, but the K14Q version did not⁸. The 2024 study added that K14Q binds CK2 less and that male carriers had a higher risk of sarcopenia and diabetes, depending on age and physical activity⁶.

The only clinical trial: an analog

Native MOTS-c has no published clinical trials. Its analog CB4211, developed by the company CohBar, did reach a phase 1a/1b study. According to the company's August 2021 release, phase 1a tested single and multiple doses over one week in 65 healthy adults, and the phase 1b part was randomized, double-blind and placebo-controlled: 25 mg subcutaneously once daily for 4 weeks in 20 people with obesity and at least 10% liver fat (11 on CB4211, 9 on placebo)¹².

The trial met its primary tolerability endpoint with no serious adverse events; the only event in more than 10% of treated subjects was mild to moderate injection-site reactions. ALT fell 21% vs a 4% rise on placebo, AST fell 28% vs 11%, and glucose fell 6% vs no change; body weight showed only a trend. Liver fat fell substantially in both groups, including placebo¹². We found no peer-reviewed publication of this trial in PubMed.

Where the evidence ends

• No clinical studies of the native peptide: in its July 2026 briefing document the FDA identified no clinical studies and no in-vivo pharmacokinetic data, and wrote that "the molecular targets through which MOTS-c acts remain unknown"¹³.
• Stability in blood: in vitro, MOTS-c was rapidly hydrolyzed in human blood; the FDA noted it remains to be determined whether exogenous dosing reaches active concentrations over time¹³.
• Questionable measurement: a mass-spectrometry method could not confirm the endogenous levels of 45.9 to 218.5 ng/mL reported by a commercial ELISA in 20 healthy people¹¹. Studies of circulating levels should be read with that caution.
• Conflicts of interest: several authors of the key studies declared being consultants and shareholders of CohBar, and the MOTS-c intellectual property was licensed to that company⁵⁶⁸.
• Sport: MOTS-c is listed as a prohibited substance in the Global DRO database, based on the World Anti-Doping Agency list¹³.