The senolytic research reagent commonly shortened to “FOXO4” is FOXO4-DRI: a cell-penetrating, D-retro-inverso peptide designed to disrupt an interaction between the transcription factor FOXO4 and p53. It is not the FOXO4 protein, and a generic ~1.5 kDa identity is not credible for the construct reported in the foundational study.
What Are the Key FOXO4 Research Specifications?
| Specification | Research record |
|---|---|
| Compound | FOXO4 |
| Category | longevity |
| Listed purity | >99% |
| Molecular weight | Sequence-dependent; not a ~1.5 kDa generic peptide |
| Intended use | Laboratory research only |
What Is the Chemical Identity of FOXO4?
FOXO4-DRI combines a FOXO4-derived p53-interaction sequence with a cationic cell-penetrating segment and uses D-amino acids in reverse order to mimic the side-chain topology of the parent L-peptide while resisting proteolysis. Sequence, stereochemistry, terminal groups and salt form are all part of its identity. Different “FOXO4 peptides” can therefore have different mass, uptake and activity.
What Does the Evidence Say About FOXO4?
The 2017 study that introduced FOXO4-DRI proposed that FOXO4 helps retain active p53 in nuclear foci in senescent cells. Disrupting that interaction promoted p53 nuclear exclusion and apoptosis preferentially in the senescent models tested. These data established a research hypothesis, not universal selectivity for every senescent cell type. A 2025 structural study further showed that both the FOXO4-derived region and the cell-permeability segment contribute to the interaction with the disordered p53 transactivation domain.
How Should a FOXO4 Study Be Designed?
Confirm senescence with multiple markers rather than SA-β-gal alone; combine cell-cycle arrest, p16/p21, SASP and DNA-damage markers. Compare proliferating and senescent cells from the same lineage. Include vehicle, a sequence-scrambled D-peptide and a non-senolytic cell-penetrating control. Measure intracellular exposure and apoptosis directly, and test p53 dependence genetically or pharmacologically.
How Should FOXO4 Be Handled and Verified?
Require the complete sequence, D/L configuration, terminal modifications and counterion on the CoA. Verify intact mass and, where feasible, stereochemical identity. Highly cationic peptides can adsorb to plastic and bind serum proteins; quantify recovery in the intended matrix and use low-binding tubes. Prepare single-use aliquots and avoid repeated freeze-thaw cycles. Cell assays also require a lot-specific endotoxin result.
Which Sources Support FOXO4 Research?
- Baar et al., targeted apoptosis of senescent cells with FOXO4-DRI, Cell (2017), DOI: 10.1016/j.cell.2017.02.031.
- Bourgeois et al., structural characterization of p53 binding by FOXO4-DRI, Nature Communications (2025), PMID 40593617.
How Can FOXO4 Results Be Interpreted Without Overclaiming?
The strongest FOXO4 evidence connects identity to mechanism to phenotype in that order. For FOXO4, chemical identity, target engagement and downstream phenotype are separate layers. A change in migration, viability or gene expression does not by itself prove the proposed molecular target. A useful study includes an orthogonal analytical identity check, a target-dependent perturbation and a second assay that measures the same biology by a different method. This design makes a positive result easier to reproduce and a negative result easier to interpret.
For citation-ready FOXO4 reporting, provide raw concentration units, biological replicate counts, prespecified exclusions and the exact time point. Separate exploratory endpoints from confirmatory ones. If exposure was not measured, describe potency as nominal rather than intracellular or free concentration. Limit the conclusion to the model used; avoid converting a pathway observation into a claim about clinical benefit.
Is FOXO4 for Research Use Only?
FOXO4-DRI is supplied for laboratory research only. It is not for human or veterinary use.
What Are Common Questions About FOXO4?
What is FOXO4?
The senolytic research reagent commonly shortened to “FOXO4” is FOXO4-DRI: a cell-penetrating, D-retro-inverso peptide designed to disrupt an interaction between the transcription factor FOXO4 and p53. It is not the FOXO4 protein, and a generic ~1.5 kDa identity is not credible for the construct reported in the foundational study.
How should researchers verify FOXO4?
Confirm the exact molecular form on the lot certificate and pair chromatographic purity with an orthogonal identity method such as mass spectrometry or NMR. Use the molecular weight, counterion and content stated for that verified form when calculating molarity.
Is FOXO4 intended for human use?
FOXO4 is listed for controlled laboratory research only. It is not intended for human or veterinary use.