Figure 4.

A summary of intracellular damage known to accumulate in cellular senescence caused by ROS. ROS induce oxidative damage to all essential macromolecules (DNA, protein, lipids) and organelle constitutes. Among organelles, mitochondria and lysosomes are more sensitive to oxidative stress conditions because of their high iron content. During senescence, lysosomes accumulate lipofuscin and display impaired autophagic degradation, diminishing mitochondrial turnover. Dysfunctional mitochondria accumulate and often produce excess ROS, further targeting intracellular macromolecules and lysosomes. These feedback loops potentiate cellular damage and aggravate cellular senescence. Iron most likely plays an essential role, as it catalyzes the generation of highly reactive free radicals able to induce oxidative damage to cellular constitutes. The figure was partly generated using Servier Medical Art, provided by Servier, licensed under a Creative Commons Attribution 3.0 unported license.