【老人病研究所公開セミナー】UVA induces oxidative stress in skin keratinocyte mitochondria but not cytosol.
＜演者＞生化学部門 Alexander M. Wolf先生
＜概要＞ Skin aging is determined by intrinsic and extrinsic factors. Extrinsic factors include ultraviolet (UV) light exposure and environmental contaminants. UV light-induced photodamage can visibly accelerate skin aging. More than 95% of UV is UVA (320-400 nm), and many aspects of photoaging have been attributed to UVA-mediated oxidative stress.
We generated transgenic mice expressing ratiometric redox-sensitive green fluorescent protein (roGFP) in cytosol or mitochondria of a wide range of tissues, including skin epidermal keratinocytes. These mice were crossbred with hairless albino mice to allow non-invasive optical measurement of skin oxidative state. Exposing skin to 365 nm UVA radiation oxidized roGFP in keratinocyte mitochondria, but not cytosol. This indicates that the endogenous photosensitizers that mediate UVA-induced oxidative stress are located mostly in mitochondria. This finding could also explain the overlapping phenotype of intrinsic aging and photoaging, as mitochondria play a central role in aging and inflammation. Direct measurements of redox state in vivo using roGFP will be very useful in evaluating treatments that aim or claim to have anti-aging effects.