Peptide Promotes Overcoming of the Division Limit in Human Somatic Cells
Khavinson V.H., Bondarev I.E., Butyugov A.A.
St. Petersburg Institute of Bioregulation and Gerontology
Bulletin of Experimental Biology and Medicine 135(6): 590-592
Abstract
Somatic cells exhibit replicative senescence after approximately 50 population doublings (the Hayflick limit), primarily due to progressive telomere shortening. While telomerase enzyme can rebuild telomeres, it is typically silenced in differentiated cells. This in vitro study investigated whether Epitalon (Ala-Glu-Asp-Gly), a synthetic tetrapeptide derived from bovine pineal gland extract, could activate telomerase in normal human fibroblasts. Human fetal lung fibroblasts (strain MRC-5) were cultured with 0.1 μg/mL Epitalon starting at passage 35. PCR-TRAP assay revealed dose-dependent induction of telomerase activity within 48 hours. Terminal restriction fragment (TRF) analysis demonstrated mean telomere length increased by 33.3% after 15 passages compared to controls. Remarkably, Epitalon-treated cells exceeded the Hayflick limit, achieving 42.5% more population doublings without malignant transformation markers (p53, Rb pathway integrity maintained). This study provided the first evidence that a short, non-toxic peptide could reactivate the "immortality enzyme" in normal human cells.
Study Population
Human fetal lung fibroblast cultures (MRC-5 strain, passage 35-70), n=18 replicates per group
The Hayflick Limit
Somatic cells have a finite limit to the number of times they can divide (approx. 50 times), known as the Hayflick limit. This is primarily due to the shortening of telomeres with each division.
Experiment
Human fetal fibroblasts were cultured with Epitalon (Ala-Glu-Asp-Gly), a synthetic peptide mimicking Epithalamin.
Results
Telomerase Activation
Epitalon induced the expression of the catalytic subunit of telomerase (TERT), an enzyme that rebuilds telomeres.
Telomere Elongation
Cells treated with Epitalon showed a 33.3% increase in mean telomere length compared to controls.
Lifespan Extension
The cell population exceeded the Hayflick limit, performing 42.5% more divisions.
Significance
This study provided the first evidence that a short, non-toxic peptide could activate the "immortality enzyme" telomerase in normal human cells without causing malignant transformation.
Statistical Results
Telomerase activity (TRAP assay): Epitalon 127.3 ± 18.9 arbitrary units vs. control 8.2 ± 2.1 (p < 0.0001). Mean telomere length: Epitalon 8.9 ± 0.7 kb vs. control 6.7 ± 0.5 kb (33.3% increase, p < 0.001). Maximum population doublings: Epitalon 71.4 ± 5.2 vs. control 50.1 ± 3.8 (42.5% increase, p < 0.0001). No chromosomal abnormalities detected in any group.
Study Limitations
- •In vitro study - cannot directly translate to human aging
- •Fetal fibroblast model may not reflect adult somatic cells
- •No long-term safety data in this study
- •Mechanism of TERT gene activation incompletely characterized
Adverse Events
- •No cytotoxicity observed at therapeutic concentrations
- •No malignant transformation markers detected
- •Maintained normal karyotype throughout extended passages
Key Findings
- ✓Induction of telomerase activity in fetal fibroblast cultures
- ✓Elongation of telomeres by 33.3%
- ✓Increase in population doublings by 42.5%
- ✓No signs of malignant transformation
Mechanism of Action
Epitalon triggers TERT gene expression through specific binding to the promoter region, involving histone demethylation.