Humanin

Discovery and Origin

Humanin is a 24-amino-acid peptide with the sequence MAPRGFSCLLLLTSEIDLPVKRRA, encoded within the 16S ribosomal RNA gene of mitochondrial DNA. It was the first mitochondrial-derived peptide ever identified — discovered in 2003 by Yuichi Hashimoto and colleagues in Japan, who isolated it from surviving neurons in the occipital cortex of an Alzheimer's disease patient while screening for factors that protected cells from amyloid-beta toxicity. The discovery was essentially accidental and opened a new category of signaling molecules.

Subsequent work by the laboratory of Pinchas Cohen at USC established humanin as the founding member of a broader family of mitochondrial-derived peptides (MDPs) that now includes MOTS-c and the six SHLP peptides. A more potent synthetic analogue, HNG (humanin with a serine-14-to-glycine substitution), is used in most research settings because of its roughly 1,000-fold greater cytoprotective potency.

Mechanism of Action

Humanin is predominantly cytoprotective, and it acts through several converging mechanisms:

• Suppression of apoptosis. Humanin binds pro-apoptotic Bcl-2 family members (Bax, Bid, BimEL), inhibiting their mitochondrial translocation and preventing cytochrome-c release. This interaction is structurally characterized and is the most firmly established of humanin's molecular mechanisms.
• Receptor signaling. A receptor complex composed of formyl peptide receptor 2 (FPR2/FPRL1) and the CNTF/IL-27 receptor family members mediates several of humanin's extracellular effects, including STAT3 activation.
• IGF-1 and insulin interaction. Humanin modulates IGF-binding protein 3 signaling and improves insulin sensitivity in metabolic models.

Circulating humanin levels decline substantially with age in humans. Long-lived mouse models (Ames dwarf, growth-hormone receptor knockout) maintain higher humanin levels than wild-type controls, and centenarians and their offspring show elevated humanin relative to age-matched controls — associations that have reinforced its connection to longevity biology.

Preclinical Evidence

The preclinical literature on humanin and its analogues is substantial and spans several therapeutic areas:

• Alzheimer's disease models. Humanin protects cultured neurons from amyloid-beta toxicity and reduces cognitive decline in transgenic mouse models — the original discovery context.
• Cardiovascular protection. HNG reduces infarct size in ischemia-reperfusion models and has shown protective effects in atherosclerosis and doxorubicin cardiotoxicity.
• Metabolic disease. Humanin administration improves glucose tolerance and insulin sensitivity in rodent models of type 2 diabetes.
• Stroke and retinal ischemia. Preclinical neuroprotection is documented in several injury models.

Clinical Status

Despite a long preclinical track record — more than 20 years since discovery — humanin has not reached late-stage human clinical trials. Early exploratory human studies have examined humanin as a biomarker rather than a therapeutic, correlating circulating levels with mitochondrial disease, cardiovascular outcomes, and aging phenotypes. Clinical-grade therapeutic programs remain in early stages as of 2026.

Practical Considerations

Humanin used in research contexts is typically the HNG analogue, administered by subcutaneous injection in rodent dosing protocols. Human protocols in use in the peptide community are extrapolated from preclinical data and lack systematic pharmacokinetic validation. Because the evidence base does not yet include dose-ranging human work, specific protocols should be understood as speculative. Humanin is not orally bioavailable in intact form.

Regulatory and Safety Status

Humanin is not FDA- or EMA-approved for any indication. It is available only through research-chemical suppliers. The short-term safety profile in preclinical models and early human biomarker studies is favorable, but long-term human safety data does not exist. Readers should apply the usual caveats to research-chemical procurement — see our guide to evaluating peptide sources.

The Bottom Line

Humanin is arguably the most biologically interesting mitochondrial-derived peptide — the first discovered, the most mechanistically characterized, and the one with the clearest links to longevity phenotypes in long-lived humans and mice. It is also, paradoxically, one of the furthest from clinical deployment given the length of time it has been studied. For readers interested in the broader class of MDPs, MOTS-c is the more metabolism-focused sibling, and our biological age primer places humanin in the context of aging biomarkers.