Humanin (HN)

What is Humanin?

Humanin was discovered in 2001 in one of the more remarkable experiments in neuroscience: researchers were screening a cDNA library from the surviving neurons of an Alzheimer's disease brain — looking for what those neurons were producing that allowed them to survive while their neighbors died. What they found was a novel 21-amino-acid peptide encoded in the mitochondrial genome (specifically in the 16S rRNA region), which they named Humanin for its ability to protect human neurons from Alzheimer's-related toxicity. It was the first mitochondria-derived peptide discovered, predating MOTS-c by 14 years.

Humanin's mechanism is primarily anti-apoptotic and cytoprotective. It protects neurons from beta-amyloid toxicity, from oxidative stress, from chemotherapy-induced cell death, and from multiple other apoptotic stimuli. It does this through a remarkable range of mechanisms: intracellular binding to the pro-apoptotic proteins BAX and IGFBP3, extracellular activation of a receptor complex (FPRL1, gp130, and WSX-1), and downstream signaling through STAT3 and PI3K/Akt.

Like MOTS-c, Humanin levels decline with age — and this decline tracks with the health outcomes that matter most for aging. Centenarian studies show that extremely long-lived individuals have higher plasma Humanin levels than age-matched controls. Humanin levels inversely correlate with cardiovascular disease risk, diabetes, and cognitive decline. Children of centenarians have higher Humanin levels than controls. These are association findings, not causal proofs, but the pattern is consistent and striking.

Humanin and MOTS-c are complementary — MOTS-c handles metabolic regulation and exercise mimicry; Humanin handles neuroprotection and anti-apoptosis. Together they represent a comprehensive mitochondria-derived peptide longevity approach addressing different aspects of mitochondrial aging.

How it works

Anti-Apoptotic Mechanisms — Intracellular

Inside cells, Humanin binds two pro-apoptotic proteins: BAX (a BCL-2 family protein that permeabilizes the mitochondrial outer membrane to trigger apoptosis) and IGFBP3 (IGF-binding protein 3, which can induce apoptosis independently of its IGF-binding function). By binding and sequestering these proteins, Humanin prevents them from executing cell death. This intracellular mechanism operates independently of cell-surface receptors and provides direct protection against multiple apoptotic stimuli.

Receptor-Mediated Signaling — Extracellular

Humanin also acts extracellularly through a receptor complex comprising FPRL1 (formylpeptide receptor-like 1), gp130 (the IL-6 signal transducer), and WSX-1 (a cytokine receptor subunit). This trimeric receptor activates JAK2/STAT3 and PI3K/Akt signaling — major pro-survival, anti-apoptotic, and anti-inflammatory pathways. The gp130 involvement links Humanin to the broader CNTF/IL-6 family of neurotrophic cytokines.

Neuroprotection Against Alzheimer's Toxicity and Insulin Sensitization

Humanin's original activity — protection against beta-amyloid (Aβ) toxicity — operates through direct binding to Aβ peptides (preventing oligomerization), receptor-mediated activation of pro-survival signaling in neurons, and anti-inflammatory effects that reduce neuroinflammation. In multiple Alzheimer's mouse models, Humanin reduced amyloid burden and improved cognitive performance. Separately, Humanin improves insulin sensitivity through PI3K/Akt activation in peripheral tissues — complementing MOTS-c's AMPK-mediated insulin sensitization through a different upstream trigger.

What the research shows

What the community reports

Humanin has a smaller but growing biohacker community — primarily people who have read the mitochondria-derived peptide literature and are building comprehensive MDP stacks alongside MOTS-c. Because there are no human interventional trials, community reports are the primary source of practical experience.

Common misconceptions