Figure 2.

Mechanisms of UV-induced apoptosis. (i) UV induces DNA damages followed by p53 activation and leakage of cytochrome c from mitochondria; (ii) UV can also activate and cluster several cell membrane death receptors (extrinsic pathway), leading to activation of caspase cascade and apoptosis; In addition, (iii) UV-induced death receptor activation can further promote the Bax translocation to mitochondria, leading to the release of cytochrome c. Moreover, (iv) UV can induce overproduction of reaactove oxygen species (ROS), not only damaging several crucial structural and functional proteins and DNA, but also exerting the release of cytochrome c from impaired mitochondria.