Cellular aging, also known as cellular senescence, is a biological process where a cell progressively loses its ability to divide and function over time. This process is considered a primary contributing factor to the aging of the whole organism, as well as to age-related diseases.
Several factors contribute to cellular aging:
- Telomere Shortening: Each time a cell divides, the telomeres, which are protective caps at the ends of chromosomes, become shorter. When they reach a critically short length, the cell can no longer divide and becomes senescent or dies. This is often considered a primary mechanism of cellular aging.
- Oxidative Stress: Cells generate energy by using oxygen in a process that produces harmful byproducts known as reactive oxygen species (ROS). Over time, ROS can damage DNA, proteins, and lipids, leading to cellular dysfunction.
- DNA Damage: Cells can accumulate DNA damage over time due to environmental factors like radiation, chemical exposure, or simply errors in DNA replication. While cells have mechanisms to repair DNA damage, these systems are not perfect and can lead to mutations and cellular aging.
- Protein Homeostasis Disruption: As cells age, their ability to properly fold proteins and remove misfolded proteins can decline, leading to the accumulation of dysfunctional proteins and cellular aging.
- Inflammation: Chronic inflammation can accelerate cellular aging by causing DNA damage and other cellular disruptions.
- Mitochondrial Dysfunction: Mitochondria, the energy-producing organelles in cells, can become less efficient with age, leading to decreased energy production and increased oxidative stress.
Senescent cells also have an altered function. They often release inflammatory and growth factors that can affect neighboring cells and tissue function. This senescence-associated secretory phenotype (SASP) can contribute to aging and age-related diseases.
Understanding cellular aging is crucial in the study of human aging and longevity, and it has potential implications for the treatment of age-related diseases, including cancer, Alzheimer’s disease, heart disease, and more.
