The discovery of mitochondrial-derived peptides (MDPs) — short open reading frames encoded within the mitochondrial genome — has reframed how mitochondria participate in systemic metabolic regulation. The mitochondrion is no longer described purely as a passive bioenergetic organelle; it is now recognized as a source of signaling peptides that engage the nucleus and the broader endocrine network.
MOTS-c, the most studied MDP, is encoded within the MT-RNR1 (12S rRNA) gene and translated through canonical cytoplasmic ribosomes following mitochondrial export. Under conditions of metabolic stress — caloric restriction, exercise, glucose deprivation — MOTS-c translocates to the nucleus and binds chromatin in stress-response gene regions. The downstream phenotype includes AMPK activation, increased GLUT4 trafficking, enhanced fatty acid oxidation, and a partial reversal of age-associated insulin resistance.
The peptide also functions as a circulating endocrine factor. Plasma MOTS-c declines with chronological age in human cohort studies, and exogenous administration in murine models is associated with improved exercise capacity, partial restoration of insulin sensitivity, and modest extension of mean lifespan. The exercise-MOTS-c axis is of particular interest: acute exercise induces a rapid rise in skeletal-muscle MOTS-c, suggesting that some adaptive benefits of physical training may be partially mediated by this peptide signal.
Beyond MOTS-c, the broader MDP family — Humanin (MT-RNR2), SHLP1-6 — is increasingly implicated in aging biology and metabolic regulation. The field is rapidly mapping the parallel signaling axes by which the mitochondrial genome speaks to the nuclear genome to coordinate adaptive responses across cellular and organismal scales.