What it is
MOTS-c (Mitochondrial Open Reading Frame of the 12S rRNA Type-c) is a 16-amino-acid peptide with sequence MRWQEMGYIFYPRKLR (molecular weight 2,174.64 Da, CAS 1627580-64-6). It is encoded by a 51-base-pair short open reading frame (sORF) within the mitochondrial 12S ribosomal RNA (MT-RNR1) gene, rather than by nuclear DNA. This makes it one of the first identified mitochondrial-derived peptides (MDPs), alongside humanin and the SHLP 1–6 family, and the first known example of a hormone-like signaling molecule encoded directly by the mitochondrial genome. The peptide was discovered and characterized by Changhan Lee, Pinchas Cohen and colleagues at USC, with the primary publication in Cell Metabolism in 2015. The first 11 amino acid residues are conserved across 14 mammalian species, suggesting long evolutionary selective pressure on its signaling role.
In plain English
MOTS-c is a short 16-amino-acid peptide that your body actually makes inside your cells' mitochondria — the power plants that generate your energy. What makes it unusual: nearly every peptide in your body is made from your regular DNA in the cell nucleus. MOTS-c is made from the tiny separate DNA that lives inside mitochondria. It's one of the first known "mitochondrial-derived peptides" and the first example of a mitochondria-made hormone. A team at USC discovered it in 2015. The first 11 amino acids are identical in 14 different mammal species, which suggests it has been doing an important job for a long evolutionary time.
How it works
- 01
Folate-AICAR-AMPK pathway (primary mechanism)
Lee 2015 (Cell Metab 21:443-454) characterized the primary pathway through unbiased metabolomic profiling of MOTS-c-treated cells. MOTS-c inhibits the folate-methionine cycle — 5-methyltetrahydrofolate and methionine drop while homocysteine rises — which blocks de novo purine biosynthesis and causes the intermediate AICAR to accumulate more than 20-fold above baseline. AICAR is a direct AMP mimetic that phosphorylates AMPK-alpha at Thr172, activating the master cellular energy sensor. Notably this activation occurs without a drop in cellular ATP, distinguishing MOTS-c from classical energy-depletion AMPK activation. The pathway is reversible by exogenous folate supplementation in cell culture, confirming folate-cycle inhibition as the upstream target.
In plain English
It activates your cells' main energy sensor (AMPK)
The 2015 discovery study figured out how MOTS-c works by tracking all the small-molecule changes in treated cells. MOTS-c slows down a chemical cycle that uses folate (vitamin B9). That causes a molecule called AICAR to pile up more than 20 times higher than normal. AICAR looks like a low-energy signal to cells, so it flips on AMPK — the "master energy sensor" of every cell. Interestingly, it does this without actually draining the cell's energy (the way exercise would). Adding extra folate to the cells reverses the effect, which confirms that the folate pathway is the real target.
- 02
GLUT4 translocation and glucose uptake
Downstream of AMPK activation, MOTS-c promotes GLUT4 glucose-transporter translocation to the plasma membrane in skeletal muscle (Lee 2015), increasing cellular glucose uptake. In mouse high-fat-diet and age-dependent insulin-resistance models, MOTS-c administration restored whole-body glucose tolerance and insulin sensitivity on clamp testing. Muscle is the primary target tissue; effects in adipose and liver are secondary.
In plain English
It helps muscles pull sugar out of the blood
Once AMPK is on, MOTS-c tells muscle cells to move more sugar-transporters (called GLUT4) to their outer surface, so they can pull more sugar in from the blood. In mice on a high-fat diet or with age-related insulin resistance, this restored normal blood-sugar control. Muscle is the main target; effects on fat tissue and liver are smaller.
- 03
Stress-responsive nuclear translocation
Kim 2018 (Cell Metab 28:516-524) showed that under metabolic stress (glucose restriction, oxidative stress, exercise) MOTS-c translocates from cytoplasm to nucleus, where it binds chromatin and modulates expression of genes involved in AMPK signaling, glycolysis, proteostasis, and stress response. Gene-set enrichment pointed to antioxidant-response-element (ARE) programs and NRF2 targets. This gives MOTS-c a dual-compartment mechanism: a cytoplasmic metabolic-enzyme arm (folate-AICAR-AMPK) and a nuclear transcriptional arm activated specifically by stress.
In plain English
Under stress, it moves into the cell nucleus and changes gene activity
A 2018 study found a second trick: when a cell is stressed (low sugar, exercise, damage from free radicals), MOTS-c physically moves from the main cell body into the nucleus, where it changes which genes are turned on. The genes it activates are ones that help cells handle stress. So it has two jobs: an everyday metabolism job outside the nucleus, and a stress-response job inside the nucleus.
- 04
Exercise mimetic and muscle-adaptation signaling
Reynolds 2021 (Nat Commun 12:470) measured endogenous MOTS-c in human subjects before and after exercise: muscle-tissue MOTS-c rose approximately 12-fold immediately post-exercise and remained partially elevated for hours, with plasma MOTS-c rising about 50%. In aged mice, late-life intermittent MOTS-c injection (three times weekly starting at 23.5 months) improved grip strength, balance, and treadmill endurance — aged treated animals roughly doubled their running time. The paper framed MOTS-c as a 'bona fide exercise mimetic' activating the same AMPK-downstream adaptive programs as exercise itself.
In plain English
It looks and acts a lot like exercise
A 2021 study measured MOTS-c in people before and after exercising. In muscle, it shot up about 12 times after a workout. In blood, it rose about 50%. In old mice, three-times-weekly MOTS-c injections for several weeks improved grip strength, balance, and roughly doubled their treadmill running time. The researchers described it as a "true exercise mimic" — it seems to turn on the same adaptation programs that exercise itself turns on.
- 05
NAD+/SIRT1 axis and mitochondrial biogenesis
MOTS-c treatment raises intracellular NAD+ and activates SIRT1-dependent deacetylation of PGC-1α and related metabolic transcription factors, driving mitochondrial biogenesis (Lee 2015; Kim 2018). The SIRT1 dependency was shown by loss-of-function in cell models where SIRT1 knockdown blunted MOTS-c's glycolytic effect. This positions MOTS-c on the same longevity-pathway map as caloric restriction, metformin, and NAD+ precursors.
In plain English
It boosts NAD+ and activates longevity-linked enzymes
MOTS-c raises NAD+ (an energy molecule) and activates SIRT1, an enzyme tied to longevity in many animal studies. SIRT1 then helps cells build more mitochondria. When researchers deleted SIRT1 from cells, MOTS-c lost much of its effect — which proves SIRT1 is part of the chain. This lines MOTS-c up with other well-known longevity approaches like calorie restriction, metformin, and NAD+ supplements.
- 06
AMPK-HIF-1α-PFKFB3 in non-metabolic tissue (newer, single-lab)
A 2025 paper in the American Journal of Respiratory Cell and Molecular Biology reported that MOTS-c protects pulmonary vascular endothelial cells from cardiopulmonary-bypass-induced injury via AMPK-HIF-1α-PFKFB3-mediated glycolytic reprogramming. This is a single-lab preclinical finding and the first mechanistic extension of MOTS-c beyond classical metabolic tissues; it should not be treated as established until replicated.
In plain English
It may protect lung blood vessels too (single-lab finding)
A 2025 study reported that MOTS-c protects the cells lining lung blood vessels from damage during heart-lung bypass surgery. It's the first finding of MOTS-c helping tissues beyond the classical metabolism targets. But it's one lab and it's preclinical — don't treat it as established until other labs replicate it.
- 07
What is NOT known about the mechanism
No cell-surface receptor for MOTS-c has been identified. Cellular uptake, tissue distribution, and intracellular trafficking (particularly the mechanism of nuclear translocation under stress) are only partially characterized. Human pharmacokinetics of exogenous synthetic MOTS-c — plasma half-life, bioavailability by route, metabolism, elimination — are absent from peer-reviewed literature. The relationship between endogenous MOTS-c and exogenous pharmacological dosing is not worked out; physiological concentrations are in the low-ng/mL range and therapeutic-dose targets in animal studies are orders of magnitude above this.
In plain English
What we still don't know
No one has found the specific "receiver" on cells that MOTS-c attaches to. We also don't fully understand how it gets into cells or how it travels to the nucleus under stress. Nothing has been published about how the human body handles it as a drug — how long it stays, how much reaches tissues, or how fast it clears. Natural blood levels are very low; the doses used in animal studies are many times higher. How those numbers translate to humans is a total blank.