FOXO4-D-Retro-Inverso Peptide
Also Known AsFOXO4-DRI · D-Retro-Inverso FOXO4 peptide · ES2
Designed by Peter de Keizer and colleagues at Erasmus University Medical Center (Rotterdam). The peptide is a D-retro-inverso version of the FOXO4 segment that interacts with p53, making it protease-resistant while retaining binding specificity. Published in Cell in 2017 as a targeted senolytic approach.
How FOXO4-DRI Works
p53-FOXO4 Interaction Disruption
FOXO4-DRI competes with endogenous FOXO4 for binding to p53 in senescent cells. In senescence, FOXO4 sequesters p53 in PML (promyelocytic leukemia) nuclear bodies, preventing p53 from translocating to the cytoplasm where it would trigger mitochondrial apoptosis. FOXO4-DRI displaces this interaction, freeing p53 to execute its pro-apoptotic program.
Selective Senescent Cell Apoptosis
The selectivity of FOXO4-DRI for senescent cells arises because the FOXO4-p53 survival mechanism is uniquely active in senescent cells. Non-senescent cells do not depend on FOXO4-mediated p53 sequestration for survival, so FOXO4-DRI does not trigger apoptosis in proliferating or quiescent normal cells.
SASP Reduction
By eliminating senescent cells, FOXO4-DRI indirectly reduces the senescence-associated secretory phenotype (SASP) — the pro-inflammatory cocktail of cytokines (IL-6, IL-8, IL-1beta), MMPs, and growth factors secreted by senescent cells that drives chronic sterile inflammation and tissue dysfunction in aging.
Published Research
Cellular Senescence Clearance
StrongThe foundational 2017 Cell paper demonstrated that FOXO4-DRI selectively induces apoptosis in senescent cells (identified by p21, SA-beta-gal, and SASP markers) while sparing non-senescent cells in vitro. Mechanism confirmed through FOXO4-p53 co-immunoprecipitation and PML body disruption assays.
Aging & Healthspan in Mice
ModerateIn naturally aged and fast-aging (XpdTTD/TTD) mice, FOXO4-DRI treatment restored fitness (running wheel activity), fur density, and renal function. Treated mice showed reduced senescent cell burden (p16INK4a, p21 markers) and reduced SASP-driven tissue inflammation compared to vehicle controls.
Chemotherapy-Induced Senescence
PreclinicalDoxorubicin-induced senescence in mice was counteracted by FOXO4-DRI treatment, reducing hepatotoxicity and restoring liver function markers. This suggests potential utility for clearing therapy-induced senescent cells that persist after cancer treatment and drive long-term side effects.
Organ-Specific Aging Research
PreclinicalPreclinical evidence demonstrates effects on kidney function restoration in aged mice (improved creatinine clearance, reduced tubular damage) and improved skin thickness/fur density. Organ-specific effects correlate with local senescent cell burden reduction.
Safety Profile
Preclinical studies in mice showed the peptide was well-tolerated with no observed toxicity to non-senescent tissues. Mild and transient side effects (reduced food intake, weight loss) were observed in initial treatment phases but resolved. No human clinical trials have been conducted. The D-retro-inverso design confers protease resistance, extending in vivo half-life. Theoretical risk of immunogenicity as a large peptide has not been specifically assessed.
Handling & Storage
FOXO4-DRI is a large, complex peptide (~48 residues, all D-amino acids). Reconstitute carefully with bacteriostatic water. Store lyophilized powder at -20°C. Reconstituted solution at 2-8°C, use within 14 days. The D-amino acid composition provides protease resistance but the molecule is sensitive to aggregation — do not vortex.
Peer-Reviewed Literature
- 1
Targeted apoptosis of senescent cells restores tissue homeostasis in response to chemotoxicity and aging
Baar MP, Brandt RMC, Putavet DA, et al.
- 2
The fountain of youth by targeting senescent cells?
de Keizer PLJ.
- 3
Cellular senescence: a translational perspective
Kirkland JL, Tchkonia T.
FOXO4-DRI FAQ
What is FOXO4-DRI?
FOXO4-DRI is a D-retro-inverso peptide designed to selectively eliminate senescent cells (senolytics). It works by disrupting the interaction between FOXO4 and p53 that senescent cells use to avoid apoptosis. By displacing FOXO4 from p53, it allows p53 to trigger mitochondrial apoptosis specifically in senescent cells.
What does 'D-retro-inverso' mean?
D-retro-inverso (DRI) is a peptide engineering strategy where the amino acid sequence is reversed and all L-amino acids are replaced with D-amino acids. This maintains a similar side-chain topology to the original L-peptide while rendering the molecule resistant to protease degradation, extending its biological half-life.
Why does FOXO4-DRI only kill senescent cells?
The selectivity comes from the specific vulnerability it targets. Only senescent cells rely on FOXO4 sequestering p53 in PML nuclear bodies to avoid apoptosis. Normal proliferating or quiescent cells do not depend on this mechanism, so disrupting the FOXO4-p53 interaction has no effect on their viability.
Has FOXO4-DRI been tested in humans?
No human clinical trials have been conducted as of the current literature. All published data comes from in vitro senescent cell models and in vivo mouse studies (naturally aged, fast-aging, and chemotherapy-treated). Clinical translation remains an active area of research.
How should FOXO4-DRI be stored?
Store lyophilized FOXO4-DRI at -20°C. Reconstitute gently with bacteriostatic water — do not vortex, as the large DRI peptide is prone to aggregation. Refrigerate reconstituted solution at 2-8°C and use within 14 days.
FOXO4-DRI Products
All compounds 99%+ purity, verified by Janoshik Analytical. GMP-manufactured lyophilized powder.
FOXO4-DRI
10mgThe zombie cell killer — selectively destroys the senescent cells that cause aging, inflammation, and tissue decline, while leaving healthy cells untouched.
- Selectively kills senescent 'zombie' cells that cause aging
- Restored fitness, hair density, and kidney function in aged mice
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Disclaimer: This monograph is provided for educational and research purposes only. G26x Peptides products are sold exclusively as research chemicals. They are not intended for human consumption, therapeutic use, or as dietary supplements. All research should be conducted in compliance with applicable laws and institutional review board protocols. Information presented here is sourced from published peer-reviewed literature and does not constitute medical advice.