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SHLP-2

A 26-residue mitochondrial-derived peptide that protects cells from apoptosis, improves insulin sensitivity and shows a striking inverse association with prostate cancer risk in human cohorts.

Also known as Small humanin-like peptide 2, SHLP2

In vitro only — Cell or tissue studies. A mechanism, not yet an effect in a living body.

Cell-culture work plus limited rodent data and one interesting human genetic association with prostate cancer risk. There is no interventional human evidence and no dosing precedent. It appears on longevity lists because of what it might be, not because of anything it has been shown to do in a person.

How it works

SHLP-2 is one of six small humanin-like peptides encoded in the same mitochondrial 16S rRNA region as humanin. In cell work it maintains mitochondrial membrane potential, increases oxygen consumption rate and ATP output, reduces reactive oxygen species and blocks caspase-3 activation under stress. It enhances insulin-stimulated glucose uptake and, in retinal pigment epithelium models, protected against the mitochondrial dysfunction characteristic of age-related macular degeneration. A genetic variant altering SHLP-2 has been associated with substantially lower prostate cancer risk in European-ancestry men, which is one of the more interesting human signals for any mitochondrial-derived peptide. Like humanin, circulating levels decline with age.

Targets: Mitochondrial membrane potential, Caspase-3 / intrinsic apoptosis, Insulin signalling, Mitochondrial biogenesis

Dosing

ProtocolDoseFrequencyRoute
Research use only — no human protocol existsn/a—not establishedsubcutaneous
  • · SHLP-2 is rarely sold, and when it is, it is as a small research vial. No dose-finding work has been published in any species that would justify quoting a human number, and inventing one here would be worse than saying nothing.

Cycling

No cycle guidance exists because no protocol exists. Anyone using this is running an experiment of one with no reference points.

Work out your exact syringe units →

Pharmacology

Half-life
Not established. Assumed short, like the rest of the family, but no pharmacokinetic study exists in any species at a useful level of detail.
Onset
Unknown. No human has been dosed in a published study.
Routes
subcutaneous
Molecule
Mitochondrial-derived peptide (26 residues)
Sequence length
26 amino acids

Handling

Diluent
Bacteriostatic water
Typical mix
1 or 2 mL
Lyophilised
Freezer.
Reconstituted
Refrigerated and used quickly; no stability data are published.
Light sensitive
Yes — keep it out of the light

Mixing

Sold in milligram or sub-milligram research quantities; dilution needs to be planned around a very small total mass.

Side effects

  • commonUnknown — no human safety data— There is genuinely nothing to report. That absence is itself the safety information.
  • commonInjection-site irritation— Expected of any subcutaneous peptide.

Do not use if

  • Pregnancy and breastfeeding — no data.
  • Active malignancy — SHLP-2 is anti-apoptotic, and that is the wrong signal to give a cancer cell even if the epidemiology points the other way.

Combining it

  • redundanthumanin — Same peptide family, overlapping cytoprotective and metabolic actions.
  • conflictshlp-6 — SHLP-6 is pro-apoptotic where SHLP-2 is anti-apoptotic; running them together is mechanistically self-cancelling.

What to monitor

  • · Nothing established.
  • · Fasting glucose and insulin are the only markers with any theoretical relevance.

Legal status

Not approved anywhere; a research reagent rather than a consumer peptide.

References

  • Cobb et al. 2016, Aging — naturally occurring mitochondrial-derived peptides are age-dependent regulators of apoptosis, insulin sensitivity and inflammatory markers (preclinical)
  • Nashine et al. 2018 — protective effects of SHLP2 in a macular degeneration model (preclinical)

Mechanism in depth

SHLP-2 sits in the same genomic neighbourhood as humanin and behaves like a somewhat blunter version of it. In cell work it preserves mitochondrial membrane potential under stress, raises oxygen consumption rate and ATP output, reduces reactive oxygen species generation, and blocks caspase-3 activation — so the anti-apoptotic action is downstream of the same intrinsic pathway humanin guards, but the specific molecular partner has not been pinned down the way BAX was for humanin. It also enhances insulin-stimulated glucose uptake, and in retinal pigment epithelium models derived from age-related macular degeneration patients it restored oxidative phosphorylation complex subunit levels toward normal, which is a more specific and more mechanistically legible result than most of what exists for this peptide. The human signal that makes SHLP-2 interesting is genetic rather than pharmacological. A coding variant of SHLP2 has been associated with substantially lower prostate cancer risk in men of European ancestry, and a separate 2024 Molecular Psychiatry paper identified a naturally occurring SHLP2 variant as a protective factor in Parkinson's disease. Two independent disease associations with sequence variants in a peptide this small is a meaningful signal that the peptide does something in people. It is emphatically not evidence that injecting it helps anyone. Circulating SHLP2 declines with age, as with the rest of the family.

What usually goes wrong

The main thing that goes wrong is that you spend money on a laboratory reagent. SHLP-2 is rarely sold, sold in sub-milligram to low-milligram research quantities, and there is no dose-finding study in any species that would justify quoting a human number — which means any protocol you find online was made up by someone. The second problem is analytical: at these quantities, the difference between a correctly synthesised 26-mer and a truncated or misfolded product is invisible to you, and there is no community body of experience to compare against because almost nobody runs it. The third is the same anti-apoptotic caution that applies to humanin, and it applies with less information behind it. The fourth is the interpretation error that gets made constantly with this compound: the prostate cancer association is about an inherited variant in the SHLP2 coding sequence, in a population study. It is not evidence that injecting SHLP-2 lowers cancer risk, and reading it that way inverts the anti-apoptotic caution into a false reassurance.

Bloodwork worth running

MarkerWhenWhy it matters
Fasting glucose and fasting insulinBaseline and at four to six weeks.Improved insulin-stimulated glucose uptake is the only effect with any plausible route to a measurable human endpoint. If you cannot see movement here, you have no read on this compound at all.Act if: No movement means no evidence of effect. There is no established dose to escalate to, so 'no movement' should mean stop rather than increase.
CBC with differential and age-appropriate cancer screeningBefore starting; keep normal screening current.Same reasoning as humanin: SHLP-2 is anti-apoptotic, and a systemic anti-apoptotic signal with zero human safety data is not something to run with an undetected malignancy. The prostate cancer epidemiology points the protective way, but that is about an inherited sequence variant, not about injecting the peptide, and the two are not the same claim.Act if: Any unexplained finding — stop and investigate.

Pharmacokinetics

Metabolism
Presumed proteolytic. Not characterised.
Elimination
Unknown.

Receptor targets

  • Mitochondrial membrane potential and oxidative phosphorylation complexes — No defined binding partner identified.

    Preserved membrane potential, increased oxygen consumption rate and ATP production, restored OXPHOS complex subunit levels in retinal pigment epithelium models of macular degeneration.

  • Caspase-3 / intrinsic apoptosis pathway — Not a direct binder as far as published work shows.

    Blocked caspase-3 activation and reduced apoptosis under oxidative stress. The upstream node is not identified — unlike humanin, there is no SHLP-2-BAX equivalent in the literature.

  • Insulin signalling — Not characterised.

    Enhanced insulin-stimulated glucose uptake in cell and rodent work.

  • Reactive oxygen species generation — Not applicable.

    Reduced ROS production, likely secondary to improved electron transport efficiency rather than through direct scavenging.

What to expect, and when

Unknown. No human has been dosed in a published study, no animal dosing schedule has been established for therapeutic use, and there is nothing honest to say about a time course. Anyone quoting one is inventing it.

Stacking and comparisons

SHLP-2 and humanin are redundant rather than synergistic — same family, same anti-apoptotic direction, overlapping metabolic effects, and no evidence that either adds anything to the other. If you are going to run one of them, run humanin, which has roughly ten times the literature and an identified molecular target. SHLP-2 and SHLP-6 is the one genuinely self-defeating combination in this class: SHLP-6 promotes apoptosis, SHLP-2 blocks it, and they come from the same 100-odd base pairs of mitochondrial DNA. Running both is not covering your bases, it is cancelling your dose. Pairing with MOTS-c is mechanistically non-overlapping and therefore at least coherent, though it means running two compounds that have never been given to a human. There is no known interaction with anything conventional.

Against humanin: humanin is the better-characterised sibling by a wide margin — defined receptor complex, identified BAX interaction, far more literature, and the same broad phenotype. There is no reason to choose SHLP-2 over humanin on evidence. Against MOTS-c: MOTS-c has an identified direct protein partner, human polymorphism data linked to a measurable phenotype, and actual rodent efficacy studies with dosing. Against SS-31: not comparable — one is an approved drug, the other is a reagent. SHLP-2's genuine distinction within the family is the strength of its human genetic associations, in prostate cancer and now Parkinson's disease. That is interesting biology and a reason to watch the compound. It is not a reason to inject it.

Rough cost

Not meaningfully estimable. SHLP-2 is sold as a research reagent in sub-milligram to low-milligram quantities at research-reagent pricing, which is not comparable to peptide-vendor pricing per milligram, and there is no established dose against which to compute a monthly cost. Any per-month figure would imply a protocol that does not exist.

Genuinely uncertain

  • No pharmacokinetic data exist in any species — no half-life, no clearance, no distribution.
  • No dose has been established in any species for therapeutic use, so no human dose can be quoted honestly.
  • The upstream molecular target of the anti-apoptotic effect is unidentified. Unlike humanin, there is no known direct protein binding partner.
  • Molecular weight is not stated in the Core record and I did not resolve a published value; it is not calculated here rather than presenting arithmetic as a source.
  • Whether the peptide crosses the blood-brain barrier is unknown, which matters given the Parkinson's association.
  • Stability of reconstituted SHLP-2 is entirely uncharacterised — no published stability data exist.
  • The prostate cancer association concerns an inherited coding variant, and the direction of effect of administering the wild-type peptide is not established by it.
  • Cost cannot be estimated because no protocol exists.

Papers