Collagen synthesis inhibition by UV

Patent Granted UV exposure would also lead to the activation of receptors for epidermal growth factor, IL-1, and TNF-α in keratinocytes and fibroblasts, which then activates signaling kinases throughout the skin via an unknown mechanism.[7] The nuclear transcription factor activator protein, AP-1, which controls the transcription of matrix metalloproteinases (MMP), is expressed and activated. MMP-1 is a major metalloproteinases for collagen degradation. This entire process is aided by the presence of reactive oxygen species that inhibits protein-tyrosine phosphatases via oxidation, thereby resulting in the up-regulation of the above-mentioned receptors. Another transcription factor NF-κB, which is also activated by UV light, also increases the expression of MMP-9. The up-regulation of MMP can occur even after minimal exposure to UV, hence, exposure to UV radiation which is inadequate to cause sunburn can thus facilitate the degradation of skin collagen and lead to presumably, eventual photoaging. Thus, collagen production is reduced in photoaged skin due to the process of constant degradation of collagen mediated by MMPs. In addition, the presence of damaged collagen would also down-regulate the synthesis of new collagen. The impaired spreading and attachment of fibroblasts onto degraded collagen could be one of the contributing factors to the inhibition of collagen synthesis.