• What factors contribute to senescence?

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    Several factors contribute to cellular senescence, affecting how cells age and function over time. Key contributors include:

    1. Telomere Attrition: Telomeres protect chromosome ends but shorten with each cell division. When they become too short, they trigger cellular senescence to prevent improper DNA repair 1 2.

    2. DNA Damage: Accumulated DNA damage from factors like radiation, or oxidative stress can cause cells to enter a senescent state as a protective measure against cancer 1 3.

    3. Replication Limits: Known as the Hayflick limit, most cells can only divide about 50 times before they stop dividing and become senescent 4 5.

    4. Mitochondrial Dysfunction: Impaired mitochondria can lead to increased reactive oxygen species (ROS), damaging cellular components and inducing senescence 3 6.

    5. Chronic Inflammation: Senescent cells secrete inflammatory molecules (SASP) that can induce senescence in neighboring cells, contributing to tissue dysfunction and aging 3 4.

    6. Environmental Stressors: UV radiation, pollutants, and other extrinsic factors accelerate cellular damage, contributing to senescence. Skin cells, for example, are particularly affected by UV exposure 2 1.

    These senescent cells accumulate with age and can lead to various age-related diseases due to their inflammatory secretions and impaired function 5.

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