MOTS-c

A mitochondrial-derived peptide identified in the last decade.

MOTS-c is a 16-amino-acid peptide (MRWQEMGYIFYPRKLR) encoded within a short open reading frame (sORF) in the 12S ribosomal RNA gene of the human mitochondrial genome. It was first identified and characterized in a 2015 publication in Cell by Chang Lee, Pinchas Cohen, and colleagues at USC. Prior to this work, the 12S rRNA gene was not known to encode a translated peptide — MOTS-c's discovery challenged the assumption that the mitochondrial genome functioned only as a source of rRNAs, tRNAs, and a fixed set of OXPHOS-complex subunits. This finding helped establish mitochondrial-derived peptides (MDPs) as a recognized and active research category.

The MOTS-c sequence is highly conserved across mammals — a finding researchers have taken as evidence of functional significance. The peptide is detectable in human plasma, and circulating levels decline with age, a pattern that has generated interest in its potential relevance to aging-associated metabolic changes and has shaped the experimental designs of a growing number of publications.

Mechanistically, the most-characterized signaling axis involves AMPK activation. MOTS-c has been shown in cell-culture and animal-model experiments to activate AMP-activated protein kinase, a central regulator of cellular energy homeostasis. Downstream effects on glucose uptake, fatty acid oxidation, and mitochondrial biogenesis have been reported in metabolically active tissues, particularly skeletal muscle. More recent work has described MOTS-c nuclear translocation under conditions of metabolic and oxidative stress, where it appears to engage nuclear transcription programs — expanding its proposed functional role beyond the mitochondrion-to-cytoplasm signaling initially described.

Animal-model studies have examined MOTS-c in the context of diet-induced insulin resistance, exercise endurance, and aging phenotypes. Studies in aged mice have reported effects on physical performance and metabolic markers that differ from those seen in young animals, suggesting age-dependent mechanisms. These findings are internally consistent across several published papers but have not yet been independently replicated at the breadth that characterizes more mature research areas.

Researchers working with MOTS-c should expect to be operating close to the active frontier of the published literature. Receptor identity, full tissue distribution, endogenous regulation, and the relative contributions of direct versus downstream signaling mechanisms remain incompletely characterized. New primary papers continue to revise the functional picture. This makes direct engagement with recent literature essential and makes review articles more likely to be incomplete or already outdated than for peptides with longer research histories.

Documents for B-2604-003.

Foundational literature.

1. Lee C. et al. (2015). The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metabolism, 21(3):443–454.
2. Reynolds J.C. et al. (2021). MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nature Communications, 12(1):470.
3. Kim S.J. et al. (2018). Mitochondrially derived peptides as novel regulators of metabolism. Journal of Physiology, 595(21):6613–6621.