Kisspeptin

FOXO4-DRI Peptide

Organisms host multiple transcription factor proteins. One such class of transcription factor proteins is the FOXO group or forkhead family of transcription factor-O,(2) which includes four members: FOXO1, FOXO3, FOXO4, and FOXO6. The FOXO4 factor is considered to regulate various cell pathways, including insulin signaling, cell cycle progression, and other functions that regulate growth and differentiation.

A synthetic version of the FOXO4 protein is FOXO4-DRI, which was developed to be identical to a fragment of the endogenously available FOXO4 protein, except for the alteration in its amino acid structure. It includes only a specific part of the FOXO4 sequence crucial for interacting with p53. FOXO4-DRI peptide, or Proxofim, is an acronym for Forkhead box O transcription factor 4-D-Retro-Inverso peptide.(3) FOXO4-DRI peptide is the same as FOXO4 protein, except that the L amino acids in its structure are replaced by D amino acids. As a result of this, FOXO4-DRI peptide may be less susceptible to the normal clearance mechanism as compared to FOXO4. It is important to note that this alteration not only potentially increases its stability but also may affect how it interacts with other cellular components compared to its natural counterpart.

Overview

The retro inverso peptides (DRI peptides) are linear chains of amino acids, where the sequence is "reversed," reversing the chirality of the structure (i.e., L amino acid structure altered to D amino acid and vice versa). D amino acids represent the mirror image of the naturally occurring L amino acids in the biological proteins. The main potential advantage of exchanging L amino acid with D amino acid is that the latter may be more resistant to degradation, making the protein structure more durable.

The main focus of FOXO4-DRI peptide research is focused on its potential to prevent the binding of the FOXO4 protein with p53 protein.(4) This interaction may be crucial as FOXO4, when bound to p53, may inhibit some of p53's key functions involved in cell cycle regulation and apoptosis. The p53 protein is an endogenous regulator protein, considered to regulate the progression of the cell cycle, including cell death. p53’s potential as a tumor suppressor is well-documented, primarily functioning to stop the proliferation of cells that have suffered DNA damage. When FOXO4 protein binds with p53, it does not appear to allow p53 to bind with DNA, thereby preventing apoptosis and cell death. This interruption may lead to the accumulation of senescent cells - those that have stopped dividing but do not die, contributing to cell aging. This process may be inhibited in the presence of FOXO4-DRI peptide, allowing p53 to bind with DNA and thereby help the cell cycle to continue to death. This potential restoration of p53’s function by the FOXO4-DRI peptide might enable it to trigger the programmed cell death of senescent cells, essentially clearing out cells that might otherwise contribute to the decline in tissue function seen in aged cell cultures.

FOXO4-DRI peptide is selective in nature and exerts this potential action only on cells that have become dysfunctional over time due to aging, known as senescent cells.(5) As a result of this biological pathway, the functioning of the tissues may be improved, aiding cell growth and differentiation.

Chemical Makeup

Molecular Formula: C228H388N86O64
Molecular Weight: 5358.05 g/mol
Other Known Titles: Forkhead box protein O4, Proxofim, FOXO4a, AFX, AFX1, MLLT7