MOTS-c mechanism of action: studies by signalling pathway
Indexed MOTS-c studies grouped by the signalling pathways they measured, with the model, evidence tier and stated limitations of each record.
By the MOTS-C Peptide editorial team·Last reviewed ·Sources: editorially approved
Short answer
The account most often cited runs in three steps, all from cell experiments: MOTS-c inhibits the folate cycle, the purine-synthesis intermediate AICAR accumulates, and AMPK is activated [Lee et al. 2015]. Separately, MOTS-c has been reported to enter the nucleus under metabolic stress [Kim et al. 2018]. No receptor or direct binding partner has been identified, so the first step in the chain remains unexplained [FDA 2026].
The proposed sequence
Metabolomic work in the discovery paper placed the folate–methionine cycle as an early point of action in cultured cells. Inhibiting that cycle reduces de novo purine synthesis, and the intermediate AICAR builds up. AICAR is an endogenous AMPK activator, which links a metabolic change to a signalling one [Lee et al. 2015]. Skeletal muscle appeared to be the primary target tissue in mice.
This is an indirect route, and worth stating plainly: in this account MOTS-c does not act on AMPK itself. The anti-doping classification of MOTS-c as an AMPK activator describes the observed outcome, not a binding interaction [WADA 2026].
Signalling to the nucleus
The 2018 follow-up reported that under metabolic stress such as glucose restriction, MOTS-c translocated to the nucleus in an AMPK-dependent manner and was associated with regulation of stress-response genes, including those carrying antioxidant response elements [Kim et al. 2018]. UniProt records nuclear interactions with the transcription factors ATF1, NFE2L2 (NRF2) and NFE2L1 on the basis of that work [UniProt 2026].
19 indexed records touch on nuclear translocation. The result has a counterpoint worth noting: a human study of skeletal muscle found that muscle MOTS-c expression was not associated with antioxidant-response-element gene expression [D'Souza et al. 2020], so the cell finding has not carried over to human tissue.
Other signalling reported
Beyond the canonical account, individual studies report changes in a range of pathways. One well-developed line describes a CK2–PTEN–mTORC2 route raising AKT phosphorylation and reducing FOXO1 activity in muscle cells, with lower plasma myostatin in treated obese mice [Kumagai et al. 2021]. Animal challenge models report AMPK and SIRT1 changes alongside reduced MAPK and NF-κB activation [Xinqiang et al. 2020].
Indexed studies by pathway measured
Counts below show how many indexed records measured something in each pathway. A larger count means more research attention, not stronger evidence; most of these records are cell or animal work.
Reported lower plasma MOTS-c concentrations in patients who developed acute lung injury after cardiopulmonary bypass. Found that MOTS-c pretreatment was associated with greater glycolytic flux, restored PFKFB3 expression, lower oxidative stress and less ferroptosis in a mouse lung ischemia-reperfusion model and in pulmonary microvascular endothelial cells, with higher phosphorylated AMPKα and HIF-1α; genetic and pharmacological PFKFB3 inhibition abolished these differences in cells.
Single-centre surgical cohort with an observational biomarker component only; mechanistic work confined to one mouse injury model and one endothelial cell type; no human exposure to MOTS-c was tested.
Marathon runners and sedentary subjects, and mice undergoing long-term endurance training
Measured serum MOTS-c levels that were closely associated with aerobic exercise capacity in marathon runners and sedentary subjects. In mice, reported higher serum MOTS-c and greater skeletal muscle mitochondrial respiration after long-term endurance training than in sedentary mice, alongside AMPK/PGC-1α activation.
Human sample sizes are not reported and the human comparison is cross-sectional, so training and selection effects cannot be separated; the mouse mechanism was not tested in people.
Peripheral blood MOTS-c from patients with hepatocellular carcinoma and healthy controls, plus Huh7 and HCCLM3 cells under hypoxia and nude mouse tumour models
Measured lower blood MOTS-c in patients with hepatocellular carcinoma than in healthy individuals. In hepatocellular carcinoma cell lines under hypoxia and in tumour-bearing mice, MOTS-c was associated with greater TRAIL-induced apoptosis and with higher MEF2A, DR4 and DR5 expression following AMPK phosphorylation.
Patient numbers are not reported and the clinical comparison is correlative; cell work uses two lines under induced hypoxia; tumours were grown in immunodeficient mice, which cannot model tumour immunity.
Paired baseline and post-treatment sera from women with HER2-positive breast cancer randomised to neoadjuvant chemotherapy and trastuzumab with or without metformin
Measured circulating MOTS-c in paired sera from women with HER2-positive breast cancer randomised to a neoadjuvant regimen with or without metformin and reported no significant change in MOTS-c in either arm over the treatment period. Reported that changes in circulating MOTS-c also did not differ significantly between patients who did and did not achieve a pathological complete response.
Sample size not stated in the abstract; secondary analysis of a trial not designed to test MOTS-c; reliance on a single commercial competitive ELISA of uncertain specificity; restricted to women with HER2-positive breast cancer receiving concurrent chemotherapy.
MOTS-c conjugated to a self-assembling Q11 peptide as a hydrogel carrier for isolated mitochondria; rat myocardial infarction model and macrophages
Reported that a MOTS-c-Q11 peptide hydrogel extended the survival and enzyme activity of isolated mitochondria and increased their internalisation by macrophages through an AMPK-dependent mechanism. Reported that in a rat myocardial infarction model the combined system was associated with less M1 macrophage infiltration, less cardiomyocyte damage and improved cardiac function and remodelling.
MOTS-c is used as part of a conjugated biomaterial rather than as the free peptide, so its independent contribution is hard to isolate; group sizes not reported in the abstract; a single rat infarction model with short follow-up.
Male mice bearing Colon-26 carcinoma; differentiated myotubes in culture
Reported that tumour-bearing mice lost body weight and that administered MOTS-c was not associated with preservation of total body weight or fat mass but was associated with preserved quadriceps mass, with a trend for gastrocnemius mass and EDL function. Reported attenuated Atrogin-1 and MuRF1 upregulation, increased inhibitory pFOXO1, reduced pFOXO3a and partial restoration of PGC-1alpha in muscle, and increased PGC-1alpha mRNA and AMPK phosphorylation in myotubes.
Male mice in a single aggressive tumour cachexia model with group sizes not reported in the abstract; effects were partial and some endpoints only trended; survival and function were assessed narrowly.
Adult male Wistar rats given continuous MOTS-c by subcutaneous micro-osmotic pump; adrenal tissue analysed
Reported that administered MOTS-c did not alter classical steroidogenic genes or circulating corticosterone and aldosterone in male rats, while RNA sequencing identified 39 differentially expressed adrenal genes, including higher P2ry4 and Apoc4 and lower Bag3, Smurf2, Slc25a30 and Pex11a. Gene set enrichment indicated lower cAMP response, mitophagy and histone deacetylation signals with higher proliferation signals in rat adrenal tissue.
Small single-sex rat sample with a short observation window; transcriptomic findings are descriptive and not functionally validated; no stimulated (ACTH or stress) condition tested.
Valproic acid-induced rat model of autism; male and female Sprague-Dawley offspring
Reported that valproic acid exposure produced impaired sociability, repetitive behaviours, Purkinje cell loss and increased oxidative stress in rat offspring, and that administered MOTS-c reversed these changes except anxiety and neocortical damage. No significant changes in plasma tetrahydrobiopterin or BDNF were detected in the rats.
Single rodent model of autism with group sizes not reported in the abstract; the proposed mediators were unchanged, so the mechanism was not established; behavioural scoring blinding not described.
Evidence tier C
How to read mechanism claims
A pathway diagram tends to imply more certainty than the underlying studies carry. Three distinctions help: whether a step was shown by manipulating the system or merely observed alongside it; whether it was seen in cells, animals or people; and whether the same group has reported it more than once. The evidence explorer exposes all three on every record.
Frequently asked questions
How does MOTS-c work?
The most cited account, from the 2015 discovery paper, is that MOTS-c inhibits the folate cycle in cells, causing the purine intermediate AICAR to accumulate, which activates AMPK. A separate line of work reports that under metabolic stress the peptide enters the nucleus. Both come from cell experiments, and no direct molecular target has been identified.
Does MOTS-c activate AMPK?
AMPK activation has been reported in cells and in animal tissues, and WADA lists MOTS-c as an example of an AMPK activator. The activation is understood to be indirect, via AICAR accumulation, rather than through MOTS-c binding AMPK itself.
What is MOTS-c nuclear translocation?
In cultured cells under metabolic stress, MOTS-c was reported to move from the cytoplasm into the nucleus in an AMPK-dependent manner, where it was linked to stress-response genes and interacted with transcription factors including NRF2 and ATF1.
What receptor does MOTS-c bind?
None has been identified. FDA stated in its 2026 review that the molecular targets through which MOTS-c acts remain unknown, which is why its organ exposure cannot be predicted.
Is the MOTS-c mechanism proven?
The individual steps have been reported in cell and animal systems. Whether the chain operates as described in human tissue has not been shown, and the absence of an identified target leaves the upstream step unexplained.
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 Metab. PubMed 25738459 · doi:10.1016/j.cmet.2015.02.009 · Study record[Animal, tier C]
Kim KH, Son JM, Benayoun BA et al. (2018). The Mitochondrial-Encoded Peptide MOTS-c Translocates to the Nucleus to Regulate Nuclear Gene Expression in Response to Metabolic Stress. Cell Metab. PubMed 29983246 · doi:10.1016/j.cmet.2018.06.008 · Study record[Cells, tier D]
Xinqiang Y, Quan C, Yuanyuan J et al. (2020). Protective effect of MOTS-c on acute lung injury induced by lipopolysaccharide in mice. Int Immunopharmacol. PubMed 31931370 · doi:10.1016/j.intimp.2019.106174 · Study record[Animal, tier C]
D'Souza RF, Woodhead JST, Hedges CP et al. (2020). Increased expression of the mitochondrial derived peptide, MOTS-c, in skeletal muscle of healthy aging men is associated with myofiber composition. Aging (Albany NY). PubMed 32182209 · doi:10.18632/aging.102944 · Study record[Human obs., tier B]
U.S. Food and Drug Administration (2026-05-11). FDA Briefing Document: MOTS-c-Related Bulk Drug Substances (MOTS-c (free base) and MOTS-c acetate). Source[retrieved 2026-11-11]
World Anti-Doping Agency (2026-01-01). The Prohibited List (S4 Hormone and Metabolic Modulators: activators of AMP-activated protein kinase). Source[retrieved 2026-11-11]