MOTS-c — a mitochondrial-derived peptide in metabolism research

MOTS-c (Mitochondrial ORF of the Twelve S rRNA type-c) is a mitochondrial-derived peptide composed of 16 amino acids, encoded not in the cell nucleus but in mitochondrial DNA. It belongs to the class of mitochondrial-derived peptides (MDPs) and is studied as a regulator of metabolism acting through the AMPK axis. It is one of the most interesting examples of the fact that mitochondria have a signalling function, not only an energy one.

This article is educational in character and constitutes a review of the published scientific literature. Most of the studies cited were carried out in animal models or under in vitro conditions; human data are limited and, where they exist, this fact is clearly noted. The text describes biochemical mechanisms, not use in humans.

What MOTS-c is — a peptide encoded in the mitochondria

For decades, mitochondria were described solely as “the powerhouses of the cell” — organelles that produce ATP. The discovery of mitochondrial-derived peptides changed this picture: it turned out that mitochondrial DNA encodes short peptides with a signalling function, communicating the energy state of the mitochondria to the rest of the cell, and even to the nucleus.

MOTS-c is one such peptide. It is a 16-amino-acid peptide encoded within the 12S rRNA gene (MT-RNR1) of mitochondrial DNA — in a short open reading frame (ORF) hidden in the sequence of the ribosomal RNA. The peptide occurs endogenously: it has been detected in cells, tissues and the circulation. Its level has been associated in studies with the metabolic state of the body and with age.

MOTS-c was first described by the team of Changhan Lee and Pinchas Cohen (2015, Cell Metabolism). That work introduced it to the literature as a regulator of metabolic homeostasis, opening a broader field of research into mitochondrial-derived peptides as signalling molecules.

A mitochondrial-derived peptide (MDP) is a class of peptides encoded in mtDNA, to which — alongside MOTS-c — belong, among others, humanin and the SHLP peptides. Their common feature is a role in the communication between the mitochondria and the rest of the cell and in the response to metabolic stress.

The discovery of this class of peptides shifted the understanding of the role of the mitochondria. Traditionally seen as executive organelles — the site of ATP production — they turned out to be also a source of regulatory molecules that co-shape the metabolism of the whole organism. In research into ageing and metabolic disorders, mitochondrial-derived peptides are analysed as potential biomarkers of the state of the mitochondria and as a starting point for understanding mitochondrial–nuclear communication. MOTS-c, alongside humanin, is one of the best-characterised representatives of this class — and it is mainly through its example that the phenomenon of signalling from the mitochondria to the nucleus has been described.

Mechanism of action — the AMPK axis and signalling to the nucleus

The mechanism of MOTS-c described in the literature rests on two connected pillars: the activation of the AMPK kinase and the ability to signal from the mitochondria to the cell nucleus.

Activation of AMPK through the folate pathway. AMPK (AMP-activated protein kinase) is the cellular “energy sensor” — triggered when the energy level in the cell falls. In studies, MOTS-c acts on the folate pathway and de novo purine biosynthesis, leading to the accumulation of the metabolite AICAR, which is a known AMPK activator. Activation of AMPK switches the cell’s metabolism towards catabolic processes — an increase in glucose uptake and substrate oxidation. This is the main pathway described through which MOTS-c affects glucose metabolism in models.

Regulation of glucose metabolism and insulin sensitivity. In animal models, MOTS-c has been associated with improved glucose metabolism and insulin sensitivity, particularly under the load of a high-fat diet. The effect is consistent with AMPK activation as the overarching mechanism.

Translocation to the nucleus under metabolic stress. One of the most interesting findings is the ability of MOTS-c to move to the cell nucleus under conditions of metabolic stress (e.g. glucose restriction or oxidative stress). In the nucleus, the peptide participates in regulating the expression of stress-response genes, including the antioxidant pathway associated with the NRF2 factor. This is an example of retrograde signalling — the mitochondria “inform” the nucleus about their state and modulate the cell’s gene programme (Kim et al., 2018).

Viewed as a whole, MOTS-c is therefore described as a molecule linking the energy state of the mitochondria with the metabolism of the whole cell — through AMPK at the level of the cytoplasm and through gene regulation at the level of the nucleus.

State of the scientific research — an overview

The MOTS-c literature is young (the peptide was described in 2015) but growing rapidly. The overview below organises the main directions, with a clear indication of the nature of the evidence.

Metabolism and insulin sensitivity. The founding work (Lee et al., 2015) showed in a mouse model that MOTS-c counteracts diet-induced obesity and improves insulin sensitivity — through the described folate/AMPK pathway.

Physical exercise and performance in ageing. MOTS-c is sometimes described as an exercise-induced peptide. In mouse models (Reynolds et al., 2021), administration of MOTS-c was associated with improved physical performance in animals of various ages, including old ones — which directed researchers’ attention to its role in muscle metabolism. These are observations from animal models, not clinical data in humans.

Nuclear signalling and the stress response. Research on nuclear translocation (Kim et al., 2018) described the involvement of MOTS-c in the adaptive response to metabolic stress and the regulation of antioxidant genes.

Ageing as a research context. The level of MOTS-c in the circulation fell with age in some studies, which made it a subject of interest in research into the metabolic aspects of ageing. This is a correlational observation and a research direction — not proof of any interventional effect in humans.

The common denominator is interpretative caution: the predominant part of the data comes from animal and cell models. The transfer of these observations to human physiology remains the subject of research, not an established fact.

MOTS-c and NAD+ and the mitochondrial axis

MOTS-c is sometimes discussed alongside another prominent direction of metabolic research into ageing — NAD+ metabolism. Both concern the mitochondria, but they act at different levels and should not be confused.

MOTS-c is a signalling peptide: it regulates metabolism through the activation of AMPK and signalling to the nucleus. NAD+ is a coenzyme essential for energy metabolism and the activity of enzymes such as the sirtuins; its pool is replenished in research with precursors, including nicotinamide mononucleotide (NMN). The mechanism of NMN is described in a separate article on NMN and NAD+ in this knowledge base.

In other words: MOTS-c and NAD+ are two different levers of the same, widely studied area — mitochondrial metabolism in the context of ageing. MOTS-c acts as a signalling molecule; the NAD+ pathway concerns the availability of the coenzyme. The broader picture of the mitochondrial axis of metabolism is organised by the thematic guide of the One-Peptides knowledge base.

The common research framework for both directions is the hypothesis that the mitochondrial function that deteriorates with age is among the processes accompanying ageing. In this context, mitochondrial-derived peptides and the NAD+ pathway are analysed as points at which mitochondrial metabolism meets the physiology of the whole cell. This is the framework within which basic research is conducted — not a claim about the efficacy of any intervention in humans.

Safety and limitations in the light of the research

MOTS-c is an endogenous peptide — it occurs naturally in the body. In animal models it was generally well tolerated. However, the limitations of the state of knowledge must be clearly noted:

• No registered medicine — MOTS-c is not registered as a medicinal product in any jurisdiction.
• Limited human data — most observations concerning humans are correlational (peptide levels), not interventional. There are no large, randomised clinical trials.
• Animal models as the basis — the most important mechanistic observations come from mice and cell cultures.
• No long-term data — the long-term profile remains undetermined.

As a result, MOTS-c remains a subject of basic research, not an established intervention.

Research reagent in the area of mitochondrial peptides

MOTS-c is available in the One-Peptides catalogue as MOTS-c 10 mg — a chemical reagent intended solely for laboratory research (Research Use Only). It is not a medicine, a dietary supplement or a product for use in humans. The quality documentation includes HPLC purity ≥98%, identity confirmation by mass spectrometry and a certificate of analysis (COA) for each batch. The peptide is used in research into the AMPK axis, glucose metabolism and mitochondrial–nuclear signalling.

Frequently asked questions

What is MOTS-c?
MOTS-c is a 16-amino-acid mitochondrial-derived peptide, encoded within the 12S rRNA gene of mitochondrial DNA. It belongs to the class of mitochondrial-derived peptides (MDPs) and is studied as a regulator of metabolism acting through the activation of AMPK and signalling to the cell nucleus. It was first described in 2015.

What is a mitochondrial-derived peptide (MDP)?
It is a class of short peptides encoded in mitochondrial DNA that perform signalling functions. Alongside MOTS-c, it includes, among others, humanin and the SHLP peptides. Their discovery showed that the mitochondria not only produce energy but also encode molecules that regulate metabolism and the stress response.

How does MOTS-c act on metabolism?
In studies, MOTS-c acts on the folate pathway and purine biosynthesis, leading to the accumulation of AICAR and the activation of AMPK — the cellular energy sensor. Activation of AMPK is associated in models with an increase in glucose uptake and improved insulin sensitivity. This is a mechanism described mainly in animal and cell models.

What does the research say about MOTS-c and ageing?
The level of MOTS-c in the circulation fell with age in some studies, and in mouse models administration of the peptide was associated with improved physical performance in older animals. These are correlational observations and results from animal models — a direction of research into the metabolic aspects of ageing, not proof of an interventional effect in humans.

MOTS-c and NMN — what is the difference?
MOTS-c is a signalling peptide that regulates metabolism through AMPK and nuclear signalling. NMN (nicotinamide mononucleotide) is a precursor of the coenzyme NAD+, replenishing its cellular pool. Both concern mitochondrial metabolism, but they act at different levels — MOTS-c as a signalling molecule, NMN as a substrate of the NAD+ pathway.

Does MOTS-c occur naturally in the body?
Yes. MOTS-c is an endogenous peptide — encoded in mitochondrial DNA and detected in cells, tissues and the circulation. In some studies its level in the circulation fell with age and changed in response to physical exercise. As a molecule naturally present in the body, it is a subject of research into the physiological role of mitochondrial peptides, not a foreign substance introduced into the system.

Summary

• MOTS-c is a 16-amino-acid mitochondrial-derived peptide (MDP), encoded in the 12S rRNA gene of mitochondrial DNA; described in 2015.
• The mechanism rests on the activation of AMPK through the folate/AICAR pathway and on translocation to the nucleus and the regulation of stress-response genes.
• In animal models, MOTS-c has been associated with the regulation of glucose metabolism, insulin sensitivity and physical performance; the peptide level fell with age.
• Human data are limited and mainly correlational — MOTS-c remains a subject of basic research.
• MOTS-c and the NAD+ pathway (NMN) are two different levers of research into mitochondrial metabolism in the context of ageing — two separate molecules with a different mechanism, analysed within the same broad research framework.

The content is educational in character and constitutes a review of the published scientific literature on the biochemistry of mitochondrial peptides. MOTS-c in the One-Peptides catalogue is a chemical reagent intended solely for laboratory research (Research Use Only) — it is not a medicine, a dietary supplement or a product for human consumption. The mechanisms and results described concern for the most part animal and cell models; they do not constitute medical advice or a suggestion to use any substance. The text does not refer to “rejuvenation”, “life extension” or other effects in humans — it describes solely molecular mechanisms and the state of the research.

Bibliography

1. Lee C et al. (2015). The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance
2. Reynolds JC et al. (2021). MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis
3. Kim KH et al. (2018). The mitochondrial-encoded peptide MOTS-c translocates to the nucleus to regulate nuclear gene expression in response to metabolic stress
4. Yen K et al. Mitochondrial-derived peptides: biology and roles in metabolism (review; DOI not verified)

Bartosz BartczakPhysiotherapist, Personal Trainer

Physiotherapist with 20 years of clinical experience, graduate of Poznan University of Medical Sciences. Founder of One Peptides and lead author of clinical-perspective content.

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