Humanin: Mitochondrial-Derived Peptide Research

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Humanin was the first mitochondrial-derived peptide ever identified. It was pulled out of surviving neurons in Alzheimer’s brain tissue in 2001, and the finding forced a revision of what mitochondrial DNA was thought to encode: not only the machinery of respiration, but short signalling peptides that act inside and outside the cell.¹

Two decades on, Humanin sits at the centre of a research field — mitochondrial-derived peptides, or MDPs — that also includes MOTS-c and the small humanin-like peptides (SHLPs). This guide covers what Humanin is, how it signals, what animal and cell models have reported, and where the evidence stops.

Please note: research peptides supplied by Licensed Peptides are for laboratory use only and are not for human consumption, clinical use, or diagnostic purposes.

What Is Humanin?

Humanin (HN) is a 24-amino-acid peptide encoded by a short open reading frame inside the mitochondrial 16S rRNA gene, MT-RNR2.¹ It was first characterised as a “rescue factor” — a molecule that prevented neuronal death caused by a range of familial Alzheimer’s disease genes and by amyloid-β.^1,2

Two features made it unusual. First, its origin: a peptide coded by mitochondrial rather than nuclear DNA. Second, its range: it acts both intracellularly, by interfering with pro-apoptotic proteins, and extracellularly, as a secreted signal that binds cell-surface receptors.^3,4

The nuclear genome also carries close homologs at the MTRNR2L loci, sharing 92–100% sequence similarity, and cross-species orthologs exist — the rat version is known as rattin — which points to evolutionary conservation of the sequence.^1,5

Which Residues Matter?

Activity is concentrated in the Pro³–Ser¹⁴ domain. Substitutions at Ser⁷, Cys⁸, Leu⁹, Leu¹², Thr¹³, Ser¹⁴ or Pro¹⁹ abolish function, which is how researchers mapped the active core.^6,7

One substitution does the opposite. Replacing serine at position 14 with glycine produces S14G-Humanin (HNG), reported as more than a thousand-fold more potent than the native peptide in protection assays.⁷ HNG is the form used in most of the animal work described below, which matters when reading the literature: results attributed to “Humanin” are frequently results for HNG.

Other Analogues in Use

• HNGF6A — a variant studied for its effect on insulin secretion.¹³
• Colivelin — a hybrid peptide reported to act at femtomolar concentrations in neuroprotection assays.⁹
• Cyclic D-Ser14 humanin (cHND14) — a stabilised form designed to resist enzymatic degradation, studied in stroke and excitotoxicity models.¹⁰
• HNSS — a chimera combining S14G-Humanin with the mitochondria-targeted tetrapeptide SS-31, built to engage more than one pathway at once.¹⁹

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MOTS-C

The mitochondrial-derived peptide in our catalog — independently accredited by a US laboratory

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How Does Humanin Get Out of the Cell, and What Does It Bind?

Humanin has no classical signal peptide, yet it is detectable in plasma and cerebrospinal fluid. It is exported through a non-standard route governed by hydrophobic motifs in the sequence, first localising to the mitochondrial matrix before moving to the cytosol and then outside the cell.⁵ Dimerisation appears to increase activity, probably by improving receptor engagement.⁷

Once outside, two receptor systems have been described. Humanin binds the G-protein-coupled receptor FPRL1, and it also acts through a trimeric cytokine receptor complex assembled from CNTFR, WSX-1 and gp130, which activates STAT3 signalling.^14,15,16,17

Inside the cell the mechanism is different again: Humanin interferes with Bax activation and interacts with Bax and Bid to reduce mitochondrial membrane permeability, blocking the apoptotic cascade at source.^3,18 It also binds insulin-like growth factor-binding protein 3, which is one route by which it influences cell survival decisions.⁴

Intracellular levels are held in check by the ubiquitin–proteasome system. The tripartite motif protein TRIM11 binds and destabilises Humanin, while proteasome inhibitors raise measured levels.¹²

What Have Animal and Cell Models Reported?

The evidence base is preclinical throughout. What follows is what was observed in specific models, not established effects.

Neurodegeneration Models

In Alzheimer’s mouse models, Humanin analogs reduced amyloid plaque burden, inflammation and cognitive deficits.^2,10 In stroke models, HNG lowered infarct size by roughly half, and the effect was greater when combined with the necroptosis inhibitor Necrostatin-1.¹⁰ In Parkinson’s models, Humanin delivered intranasally preserved dopaminergic neurons and reduced oxidative stress markers.²⁰

Work in astrocytes added a metabolic angle: Humanin is secreted by astrocytes and was reported to improve neuronal energy metabolism, which links the peptide’s neuro-protective and bioenergetic roles.¹¹

Metabolic and Glucose-Control Models

Humanin has been described as a central regulator of peripheral insulin action.¹³ In animal models it reduced hepatic glucose output and increased muscle glucose uptake; analogues improved glucose tolerance, protected pancreatic β-cells and reduced adiposity in diabetic and ageing models.^5,13 Transgenic mice with high Humanin expression resisted insulin resistance, and long-lived dwarf mice carry naturally elevated levels.⁵

Cardiovascular Models

Acute Humanin treatment attenuated myocardial ischemia and reperfusion injury in mice, reducing infarct size.⁸ In the vasculature it has been reported to lessen aortic plaque area, preserve endothelial function and reduce vascular remodelling.⁵

The most detailed cardiac ageing study gave female mice the HNG analog from 18 months to 32 months of age.²¹ Treated animals showed a higher ratio of cardiomyocytes to fibroblasts, with no significant change in other cardiac cell populations. Picrosirius red staining showed markedly less collagen: interstitial fibrosis measured 0.24 ± 0.06% in untreated aged hearts against 0.02 ± 0.01% in young controls, and HNG treatment brought aged hearts down to 0.07 ± 0.03%. Perivascular fibrosis did not differ across groups, suggesting the anti-fibrotic activity was specific to interstitial tissue. Cardiac fibroblast proliferation fell, as did expression of TGF-β1, FGF-2 and MMP-2, and myocardial apoptosis was reduced. Mechanistically the authors attributed this to upregulation of the Akt/GSK-3β pathway together with downregulation of Bax.²¹

Lifespan and Healthspan Models

Humanin expression extended lifespan in C. elegans, and in ageing mice it was associated with preserved glucose control and activity.⁵ Naked mole rats, unusually long-lived for their size, maintain youthful levels where typical rodents do not.⁵

Do Humanin Levels Change With Age?

Yes, and consistently downward. MT-RNR2 transcripts are abundant in metabolically active tissues, and the peptide is measurable in plasma and cerebrospinal fluid, but concentrations fall with age and tend to be lower again in chronic illness.^5,12

The interesting counterpoint is at the other end of the distribution: higher levels have been reported in the offspring of centenarians, which is the observation that pushed Humanin into ageing research rather than purely neuroscience.⁵ These are associations measured in populations, not demonstrations that raising Humanin extends anything in humans.

How Does Humanin Relate to MOTS-c and the Other MDPs?

Humanin was the first MDP described; MOTS-c and the SHLP family followed.⁵ They share an origin in mitochondrial DNA but divide the labour:

• Humanin (24 amino acids, from MT-RNR2) is oriented toward stress response and cell survival.
• MOTS-c (16 amino acids, from the 12S rRNA region) is oriented toward energy sensing and metabolic regulation, largely through AMPK.⁵
• SHLPs vary in direction — SHLP2 and SHLP3 promote survival, while SHLP6 has been reported as pro-apoptotic.⁵

Both Humanin and MOTS-c decline with age and rise with exercise, and both are antagonised by the regulatory protein VSTM2L, which indicates a coordinated rather than independent network.⁵ Combination approaches — Humanin with Necrostatin-1, or hybrids such as Colivelin and HNSS — have outperformed Humanin alone in the models where they have been compared.^9,10,19

What Is the Link to Cellular Senescence?

Senescent cells stop dividing but keep secreting cytokines, chemokines and matrix-remodelling enzymes, a mix known as the senescence-associated secretory phenotype (SASP). Kim and colleagues reported that mitochondrial peptides including Humanin and MOTS-c modulate mitochondrial function during senescence and shift SASP output, raising levels of factors such as IL-6, IL-1β, IL-8, IL-10 and TNF-α in senescent cultures.²²

That result connects to senolytics. FOXO4-DRI, which clears senescent cells by disrupting the p53–FOXO4 interaction, has been reported as more potent when SASP signalling is high and less potent when SASP is suppressed.²³ The hypothesis under test is whether raising SASP output makes senescent cells easier to identify and remove. It is drawn from two separate lines of evidence and has not been demonstrated as a combination effect.

Where Does Humanin Sit Among Other Neuro-Active Peptides?

Humanin is one of several peptides being examined for neurodegeneration, and it helps to see the field around it. Davunetide (NAP) is an eight-amino-acid peptide that stabilises microtubules, studied in tau-related conditions.²⁴ Elamipretide (SS-31) is a tetrapeptide that binds cardiolipin to stabilise mitochondrial structure.²⁵ P110 blocks abnormal Drp1 activity to limit mitochondrial fragmentation.²⁶ CN-105 is an APOE-mimetic pentapeptide.²⁷ RD2 is built from D-amino acids to resist degradation while binding amyloid-β oligomers.²⁸ GLP-1 analogues derived from exendin-4 are studied because both Alzheimer’s and Parkinson’s models involve impaired brain insulin signalling.^29,30

What Humanin contributes to that set is a naturally occurring, mitochondrially encoded starting point — and, in HNG, an analogue with a very large potency margin over the native sequence.

What Is Known About the Limits of This Evidence?

Three limits are worth stating plainly. Humanin’s effects are context-specific, and its anti-apoptotic activity raises questions in tumour biology that researchers treat as a caution rather than a footnote.⁵ Stability, delivery and tissue targeting remain unsolved, which is why so much of the work uses engineered analogues rather than the native peptide. And no result described on this page comes from a controlled human trial.

Research Quality and Handling

Peptide purity and contamination directly affect reproducibility, so material quality is part of the experiment. Every Licensed Peptides batch is verified to a 99%+ purity standard and ships with a batch-specific Certificate of Analysis confirming identity, purity and quality, with testing performed by independent accredited laboratories. Batches are screened for contaminants — we publish endotoxin reports and run sterility and heavy metal testing. For the underlying methods, see our guide to achieving and verifying peptide purity.

Lyophilized peptides degrade with heat, moisture, prolonged light exposure and repeated freeze-thaw cycles, so material is normally kept frozen or refrigerated per the manufacturer’s instructions and reconstituted only in the amount needed. Our guide on how to properly store peptides covers this in more detail.

FAQs

Is Humanin Approved for Human Use?

No. Humanin and its analogues are investigational and have not been approved for therapeutic, diagnostic or clinical use. Every finding described above comes from cell cultures and animal models.

What Is the Difference Between Humanin and S14G-Humanin?

A single amino acid. Replacing serine at position 14 with glycine produces S14G-Humanin (HNG), which has been reported as over a thousand-fold more potent than the native peptide in protection assays.⁷ Most published animal work uses HNG rather than native Humanin.

Is Humanin the Same as MOTS-c?

No. Both are encoded in mitochondrial DNA, but they come from different regions, differ in length (24 versus 16 amino acids) and engage different pathways — Humanin with survival and stress-response signalling, MOTS-c with energy sensing through AMPK.⁵

Does Licensed Peptides Supply Humanin?

Not currently. The mitochondrial-derived peptide in our catalog is MOTS-C, supplied for research use only.

Conclusion

Humanin changed what mitochondria were understood to do. A peptide encoded in mitochondrial DNA that blocks apoptosis from the inside and signals through cytokine receptors from the outside does not fit the older picture of the organelle as a power plant.

The preclinical record across neurodegeneration, metabolic, cardiovascular and ageing models is unusually broad for a peptide of this size, and the age-related decline in circulating levels gives researchers a clear question to test. What is missing is human data, stable delivery, and the tissue targeting that would let any of this be tested properly. Those are the next steps, and until they are taken, Humanin remains a research subject.

Note: All products are sold for research, laboratory or analytical purposes only and are not for human consumption.

References

1. Hashimoto Y, Niikura T, Tajima H, et al. A rescue factor abolishing neuronal cell death by a wide spectrum of familial Alzheimer’s disease genes and Aβ. Proc Natl Acad Sci USA. 2001;98(11):6336-6341. doi:10.1073/pnas.101133498
2. Hashimoto Y, Niikura T, Ito Y, et al. Detailed characterization of neuroprotection by a rescue factor Humanin against various Alzheimer’s disease-relevant insults. J Neurosci. 2001;21(23):9235-9245.
3. Guo B, Zhai D, Cabezas E, et al. Humanin peptide suppresses apoptosis by interfering with Bax activation. Nature. 2003;423(6938):456-461. doi:10.1038/nature01627
4. Ikonen M, Liu B, Hashimoto Y, et al. Interaction between the Alzheimer’s survival peptide Humanin and insulin-like growth factor-binding protein 3 regulates cell survival and apoptosis. Proc Natl Acad Sci USA. 2003;100(22):13042-13047. doi:10.1073/pnas.2135111100
5. Cobb LJ, Lee C, Xiao J, et al. Naturally occurring mitochondrial-derived peptides are age-dependent regulators of apoptosis, insulin sensitivity, and inflammatory markers. Aging (Albany NY). 2016;8(4):796-809. doi:10.18632/aging.100943
6. Yamagishi Y, Hashimoto Y, Niikura T, Nishimoto I. Identification of essential amino acids in Humanin, a neuroprotective factor against Alzheimer’s disease-relevant insults. Peptides. 2003;24(4):585-595.
7. Terashita K, Hashimoto Y, Niikura T, et al. Two serine residues distinctly regulate the rescue function of Humanin, an inhibiting factor of Alzheimer’s disease-related neurotoxicity: functional potentiation by isomerization and dimerization. J Neurochem. 2003;85(6):1521-1534.
8. Muzumdar RH, Huffman DM, Calvert JW, et al. Acute humanin therapy attenuates myocardial ischemia and reperfusion injury in mice. Arterioscler Thromb Vasc Biol. 2010;30(10):1940-1948. doi:10.1161/ATVBAHA.110.205997
9. Chiba T, Yamada M, Hashimoto Y, et al. Development of a femtomolar-acting Humanin derivative named colivelin by attaching activity-dependent neurotrophic factor to its N terminus. J Neurosci. 2005;25(52):10252-10261.
10. Gilon C, Gitlin-Domagalska A, Lazarovici P, et al. Novel Humanin analogs confer neuroprotection and prevent doxorubicin-induced mitochondrial dysfunction. Neuropharmacology. 2020;168:108013. doi:10.1016/j.neuropharm.2020.108013
11. Wang J, Wang Y, Lin H, et al. Humanin, a mitochondrial-derived peptide, is secreted by astrocytes and improves neuronal energy metabolism. Cell Metab. 2021;33(10):2077-2093.e9.
12. Niikura T, Kita Y, Abe Y, et al. A tripartite motif protein TRIM11 binds and destabilizes Humanin, a neuroprotective peptide against Alzheimer’s disease-relevant insults. Eur J Neurosci. 2003;17(6):1150-1158.
13. Muzumdar RH, Huffman DM, Atzmon G, et al. Humanin: a novel central regulator of peripheral insulin action. PLoS One. 2009;4(7):e6334. doi:10.1371/journal.pone.0006334
14. Ying G, Iribarren P, Zhou Y, et al. Humanin, a newly identified neuroprotective factor, uses the G-protein-coupled formylpeptide receptor-like 1 as a functional receptor. J Exp Med. 2004;199(5):621-627.
15. Hashimoto Y, Kurita M, Aiso S, Nishimoto I, Matsuoka M. Humanin inhibits neuronal cell death by interacting with a cytokine receptor complex or complexes involving CNTF receptor α/WSX-1/gp130. Mol Biol Cell. 2009;20(12):2864-2873.
16. Jia Y, Yang L, Chen Q, et al. Humanin analog protects against germ cell apoptosis via WSX-1/gp130/STAT3. Cell Death Dis. 2021;12(7):686.
17. Matsuoka M, Hashimoto Y. Humanin and the receptors for Humanin. Mol Neurobiol. 2010;41(1):22-28.
18. Ma Z, Liu Z. Humanin decreases mitochondrial membrane permeability by interacting with Bax and Bid. Biochim Biophys Acta. 2018;1859(9):789-801.
19. Qian K, et al. SS31/S14G-Humanin hybrid peptide with amplified multimodal efficacy and bio-permeability for the treatment of Alzheimer’s disease. Asian J Pharm Sci. 2024.
20. Kim KH, et al. Intranasal delivery of mitochondrial protein humanin rescues cell death and promotes mitochondrial function in Parkinson’s disease. Theranostics. 2023.
21. Chronic treatment with the mitochondrial peptide humanin prevents age-related myocardial fibrosis in mice. Am J Physiol Heart Circ Physiol. 2018;315(5):H1120-H1134. doi:10.1152/ajpheart.00685.2017. PMID: 30004252
22. Kim SJ, Mehta HH, Wan J, et al. Mitochondrial peptides modulate mitochondrial function during cellular senescence. Aging (Albany NY). 2018;10(6):1239-1256. doi:10.18632/aging.101463
23. Baar MP, Brandt RMC, Putavet DA, et al. Targeted apoptosis of senescent cells restores tissue homeostasis in response to chemotoxicity and aging. Cell. 2017;169(1):132-147.e16. doi:10.1016/j.cell.2017.02.031
24. Gozes I, et al. Unexpected gender differences in progressive supranuclear palsy reveal efficacy for davunetide in women. Transl Psychiatry. 2023.
25. Nguyen TN, et al. Neuroprotective effects of a small mitochondrially-targeted tetrapeptide elamipretide in neurodegeneration. Front Integr Neurosci. 2022.
26. Rios L, et al. Targeting an allosteric site in Drp1 to inhibit Fis1-mediated mitochondrial dysfunction. Nat Commun. 2023.
27. Krishnamurthy K, et al. ApoE mimetic peptide CN-105 reduces pathology and improves behavior in a model of Alzheimer’s disease. Brain Res. 2020.
28. Schemmert S, et al. Aβ oligomer elimination restores cognition in transgenic Alzheimer’s mice with full-blown pathology. Mol Neurobiol. 2019.
29. Kong F, et al. GLP-1 receptor agonists in experimental Alzheimer’s disease models: a systematic review and meta-analysis of preclinical studies. Front Pharmacol. 2023.
30. Lv D, et al. Neuroprotective effects of GLP-1 class drugs in Parkinson’s disease. Front Neurol. 2024.