Telomeres and Telomerase Activity Are Regulated as a Complex System in Cultured Hepatoma Cells

Non-linear dynamics, often chaotic, are now accepted as the normal way in which major physiological functions proceed, allowing adaptation. The length of telomeres, the chromosome endings, is critical in limiting cell lifespan and in controlling subsets of downstream genes. Telomere length dynamics in tumoral cells is the net result of mitotic erosion of telomeric DNA and telomere repair by the enzyme telomerase. We observed telomere length oscillations in the long-lived hepatoma Fao cell line, for forty three 6-day passages in culture. Telomerase activity oscillated with similar frequency and opposite amplitude. We mapped the combined data of telomere erosion and telomerase activity. There was reverse symmetry between consecutive periods of 10 passages. Thus, telomere length and telomerase activity can be considered to be a single complex system with strong reciprocal regulation.