# The MOTS-c, Humanin & SHLP Axis: Mitochondrial Peptides Explained

> A clinical monograph on the mitochondrial-derived peptide (MDP) axis — MOTS-c, humanin and the small humanin-like peptides (SHLP). One coherent mechanism, three very different maturity tiers, and zero approved human therapies.

*Published 2026-06-30 · Updated 2026-07-01 · By Marcus Feld, PharmD, BCPS*

The short answer
The mitochondrial-derived peptides — **MOTS-c, humanin and the SHLP family** — share one elegant biology (short peptides encoded inside mitochondrial DNA that signal cellular and metabolic fitness and decline with age), but they sit on very different maturity tiers. **MOTS-c has reached first-in-human and Phase 2a; humanin has only observational human associations; SHLP is preclinical with tiny serum-correlation data.** Across the axis, no completed human efficacy trial exists — highest grade **C (preclinical)**.[7](https://peptidevox.com/#r7)[2](https://peptidevox.com/#r2)

Mitochondrial-derived peptides (MDPs) are among the most intriguing molecules in longevity science: short, bioactive peptides translated not from the nuclear genome but from small open reading frames inside mitochondrial DNA itself. The three headline members — MOTS-c, humanin, and the six small humanin-like peptides (SHLP1 through SHLP6) — act as retrograde signals carrying information from the mitochondria to the nucleus and the wider body.[7](https://peptidevox.com/#r7) This monograph maps the shared biology of the axis, then separates what is proven in humans from what remains animal and cell-culture work.

*This article is informational and editorial content for research and educational purposes only. It is not medical advice, not a protocol to follow, and not a sourcing guide. These peptides are not FDA-approved; humanin and the SHLPs are sold as research compounds with no completed human efficacy trials. Dosing figures are reported strictly as seen in the published literature for completeness — never as recommendations. Consult a licensed clinician before any health decision.*

## What are the MOTS-c, humanin and SHLP peptides?

The founding MDP, humanin, is a 24-amino-acid peptide encoded within the mitochondrial 16S rRNA (MT-RNR2) gene. An in-silico scan of that same MT-RNR2 region — performed by Cobb, Lee and Cohen in 2016 — revealed six additional peptides, named small humanin-like peptides, ranging roughly 20 to 38 amino acids.[1](https://peptidevox.com/#r1) MOTS-c, a 16-amino-acid peptide, is encoded separately in the 12S rRNA region and functions as an AMPK activator.[7](https://peptidevox.com/#r7) Together these form the known MDP set, and a unifying observation runs through all of them: circulating levels decline with age, in both mice and humans, which is the central rationale for longevity interest.[1](https://peptidevox.com/#r1)

The standout small humanin-like peptide is **SHLP2**, a 26-amino-acid peptide (molecular weight approximately 3017 Da) that circulates in plasma and is detectable in tissue and cerebrospinal fluid.[3](https://peptidevox.com/#r3)[2](https://peptidevox.com/#r2) Tissue expression differs across the family — SHLP1 in heart, kidney and spleen; SHLP2 in liver, kidney and muscle; SHLP3 in brain and spleen — underscoring that "SHLP" is not one molecule but a heterogeneous set.[8](https://peptidevox.com/#r8)

## How does the mitochondrial peptide axis work?

The best-defined mechanism in the SHLP family is SHLP2's receptor biology. A high-throughput β-arrestin screen of 168 G-protein-coupled receptors identified the atypical chemokine receptor **CXCR7 (ACKR3)** as SHLP2's top target. SHLP2 recruited β-arrestin2 to CXCR7, reaching about 70% of the efficacy of the canonical ligand CXCL12 with an EC₅₀ near 0.97 µM, drove receptor internalization, and bound directly — while notably not engaging CXCR4.[2](https://peptidevox.com/#r2) Downstream, the cascade runs SHLP2 → CXCR7 → β-arrestin2 → ERK1/2 (MAPK) phosphorylation; a MAPK inhibitor abolished SHLP2-induced POMC neuron depolarization in hypothalamic slices, whereas a PI3K inhibitor did not.[2](https://peptidevox.com/#r2) SHLP2 has additionally been linked to STAT3 and Akt survival signaling and acts as a molecular chaperone that inhibits protein misfolding.[4](https://peptidevox.com/#r4)

Centrally, systemic or central SHLP2 induces c-Fos in the hypothalamic arcuate nucleus, preferentially activating anorexigenic **POMC neurons** over orexigenic AgRP neurons. Chemogenetic silencing of POMC neurons blunted SHLP2's appetite-suppressing and thermogenic effects, confirming POMC as the functional node.[2](https://peptidevox.com/#r2) At the organelle level, SHLP2 binds respiratory complex I, raises oxygen consumption and ATP, increases mtDNA copy number and PGC-1α (biogenesis), and lowers reactive oxygen species and caspase-mediated apoptosis.[3](https://peptidevox.com/#r3) Across the axis, humanin shares this insulin-sensitizing and anti-apoptotic profile, while MOTS-c acts chiefly through AMPK to mimic an exercise-like metabolic state.[7](https://peptidevox.com/#r7) No formal human or even rodent pharmacokinetic dataset exists for SHLP, so half-life, clearance and oral bioavailability are unreported.[2](https://peptidevox.com/#r2)

## What is the evidence by member and indication?

The entire axis is preclinical at the efficacy level. The most developed indication is metabolic: in hyperinsulinemic-euglycemic clamp studies, centrally infused SHLP2 increased glucose uptake and suppressed hepatic glucose production, and in high-fat-diet male mice, SHLP2 at 2 mg/kg/day for three weeks protected against weight gain, improved glucose tolerance and insulin sensitivity, raised energy expenditure, and upregulated brown-fat thermogenic genes.[2](https://peptidevox.com/#r2) The only human signal is a dot-blot of male sera showing lower serum SHLP2 in obese and diabetic men versus healthy controls — a correlation in a tiny sample, hypothesis-generating only.[2](https://peptidevox.com/#r2)

  The MDP axis: maturity and evidence by member

    MemberMost advanced human statusBest preclinical signalGrade

    MOTS-c (16-aa, 12S rRNA, AMPK activator)First-in-human IV study + registered Phase 2a; analog CB4211 cleared Phase 1Exercise-mimetic metabolic activationC (preclinical efficacy)
    Humanin (24-aa, MT-RNR2)Observational human associations (e.g. cognitive aging); no completed trialNeuroprotection, cytoprotection, insulin sensitizationC (preclinical)
    SHLP2 (26-aa, MT-RNR2)Tiny male-only serum correlations only; no interventional trialInsulin sensitization, anti-obesity, mitochondrial biogenesisC (preclinical)
    SHLP family direct anti-aging claimNo lifespan/healthspan intervention in any organismMechanistic + correlational onlyD (unproven)

Beyond metabolism, SHLP2 has shown cytoprotection: in human transmitochondrial ARPE-19 macular-degeneration cybrid cells, 3.2 µM SHLP2 restored OXPHOS subunits, cut caspase expression, raised mtDNA copy number and PGC-1α, and partially rescued viability after amyloid-β insult — but with no effect in normal cybrids, indicating disease-state-specific action.[3](https://peptidevox.com/#r3) The longevity rationale rests only on age-related decline of these peptides plus their mitochondrial-fitness biology; no lifespan or healthspan intervention study in any organism has been reported for SHLP, making direct anti-aging claims Grade D.[1](https://peptidevox.com/#r1) A critical caveat: the family is not uniform — SHLP2 and SHLP3 are pro-survival, SHLP4 is proliferative, and **SHLP6 is pro-apoptotic**.[5](https://peptidevox.com/#r5)

Proven vs hyped
Proven in humans: nothing for SHLP or humanin; MOTS-c has only early safety/PK and a registered Phase 2a. Hyped: consumer "longevity" and "metabolic" claims that extrapolate rodent and cell findings. Registered interventional development to watch sits with MOTS-c — you can monitor mitochondrial-peptide trial activity at [ClinicalTrials.gov](https://clinicaltrials.gov/).[7](https://peptidevox.com/#r7)

## How safe are these peptides and what is their 2026 status?

For SHLP and humanin, human safety data simply do not exist — no toxicology, no adverse-event registry, no maximum tolerated dose, because no human has been studied in a trial.[2](https://peptidevox.com/#r2) Three weeks of intraperitoneal SHLP2 in mice was reported without overt toxicity, but those studies were not designed as formal safety assessments and used males only.[2](https://peptidevox.com/#r2) The dominant theoretical concern is mechanistic: SHLP2 signals via CXCR7/ACKR3 and ERK/MAPK plus STAT3 and Akt — pathways implicated in cell survival, proliferation and tumor biology, with CXCR7 overexpressed in several cancers, making chronic agonism a theoretical oncologic and angiogenic concern.[2](https://peptidevox.com/#r2) Because research-use-only peptides are unregulated for human administration, purity, sterility, endotoxin and identity are not guaranteed — a real-world hazard independent of the molecule.[12](https://peptidevox.com/#r12) By default, pregnancy, lactation, pediatrics and active malignancy are avoid populations.

Legally, no MDP is FDA-approved for any indication.[7](https://peptidevox.com/#r7) SHLPs are not on FDA's 503A bulk-drug-substance lists and have no recognized compounding pathway; they are sold only as "research use only / not for human use" reagents, and human use violates FDA rules regardless of that label.[10](https://peptidevox.com/#r10)[12](https://peptidevox.com/#r12) Patents describe therapeutic uses for SHLP2 and the family, but a patent is not evidence of approval or human efficacy.[11](https://peptidevox.com/#r11) For athletes, the axis is effectively off-limits: MOTS-c was banned by WADA in 2024 as an AMPK-activating metabolic modulator, and although SHLPs are not individually enumerated on the 2026 Prohibited List, as injectable peptide signaling agents with metabolic, exercise-mimetic activity they plausibly fall under Section S2; competitive athletes should treat the family as prohibited and verify with their anti-doping organization.[13](https://peptidevox.com/#r13)

**Bottom line.** The mitochondrial-derived peptide axis is genuinely interesting biology — a coherent mechanism (CXCR7/ACKR3 → β-arrestin → ERK, hypothalamic POMC activation, complex-I binding and mitochondrial biogenesis) with reproducible rodent and cell-culture benefits in insulin sensitivity, anti-obesity and cytoprotection. But what is proven in humans is minimal: MOTS-c alone has reached first-in-human and a registered Phase 2a, while humanin and SHLP have no interventional human trial at all. Marketing any of these as a metabolic or longevity therapy runs ahead of the evidence (Grade D for any human-benefit claim), and the family's heterogeneity — SHLP6 is pro-apoptotic — means claims must be member-specific. Until first-in-human safety and PK studies exist for humanin and SHLP, the rung MOTS-c has already reached, those members belong in the lab, not the clinic. Regulatory and WADA facts here are current as of June 2026 and should be re-verified for any specific use.

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Source: https://peptidevox.com/peptide-encyclopedia/motsc-humanin-axis
Index: https://peptidevox.com/llms.txt · Full text: https://peptidevox.com/llms-full.txt