MOTS-c

Mechanism of action in research models

AMPK activation and metabolic regulation: in skeletal-muscle cell cultures (C2C12) and primary mouse myocytes, MOTS-c treatment increases AMPK phosphorylation at Thr172 — the activating site — and downstream effects including increased GLUT4 translocation to the plasma membrane, enhanced glucose uptake, and stimulation of fatty-acid oxidation. These effects recapitulate key cellular metabolic features of exercise.

Folate cycle and methionine metabolism: mechanistically distinctive — MOTS-c inhibits methylenetetrahydrofolate dehydrogenase (MTHFD), disrupting folate metabolism and de-novo purine biosynthesis. This causes accumulation of AICAR (5-aminoimidazole-4-carboxamide ribonucleotide), an endogenous AMPK activator. The AICAR-mediated pathway represents a unique upstream mechanism distinct from the AMP-sensing mechanism activated by conventional exercise or caloric restriction.

Nuclear translocation under stress: under glucose restriction or heat shock, MOTS-c translocates from cytoplasm to nucleus, where it binds ARE (antioxidant response element) promoter regions and modulates expression of metabolic stress-response genes — establishing MOTS-c as a mitochondria→nucleus retrograde signal.

Age-related decline and insulin resistance: MOTS-c levels in skeletal muscle decline significantly with age in rodent and human tissue, correlating with increased insulin resistance markers. Supplementation in aged mice restores insulin sensitivity and increases skeletal-muscle GLUT4 expression.

Physical-exercise response: circulating MOTS-c increases significantly in response to acute aerobic exercise in both rodent and human research subjects, positioning MOTS-c as a myokine-like “mitokine” mediating metabolic adaptations to exercise.

Research background and peer-reviewed literature

MOTS-c was announced in Cell Metabolism (2015) by Lee, Zeng, Drew et al. — a landmark paper establishing the existence of mitochondrially-encoded peptides with nuclear regulatory function. Reynolds et al. published comprehensive characterisation of exercise-induced MOTS-c dynamics in humans. Kim SJ et al. characterised MOTS-c nuclear localisation in response to metabolic stress, extending the biological role into the antioxidant stress-response domain. Comparative studies with other MDPs, particularly humanin, examine the interplay between different mitochondrially-encoded peptides in coordinating metabolic stress responses.

Reconstitution and storage protocol

1. Allow sealed vial to equilibrate to room temperature.
2. Reconstitute in bacteriostatic water or sterile PBS. MOTS-c dissolves well in aqueous buffers at physiological pH.
3. Typical research concentrations: 10 nM–1 μM in cell culture; published rodent in-vivo studies have used a 5–20 mg/kg range.
4. Filter through 0.22 μm for sterile cell-culture applications.

Storage: lyophilized at −20 °C, desiccated, light-protected (stable 24+ months). Reconstituted at 4 °C for up to 28 days; aliquot at −80 °C for extended storage.