Matrix metalloproteinases photoaging

Ryu, B., Qian, Z.-J., Kim, M.-M., Nam, K. W., and Kim, S.-K. (2009a). Anti-photoaging activity and inhibition of matrix metalloproteinase (MMP) by marine red alga Corallina pilulifera methanol extract Radiat. Phys. Chem. 78,98-105. 

Activator protein-1 (AP-1) is an important transcription factor that figures in the inflammation response. AP-1 is a dimeric complex of the protooncoproteins jun and fos that is induced by growth factors, cytokines, tumor promoters, and sunlight [39]. Activation of AP-1 increases the transcription of cytokines, such as interleukin-2, and certain matrix metalloproteinases [40]. In the presence of t-RA, RARs can inhibit the actions of AP-1. Reciprocally, elevated expression of either the jun or fos components of AP-1 can prevent activation of RAREs by RARs. This repression of gene transcription, called transrepression, is a well-known mechanism for crosstalk between retinoid receptors and AP-1 [41-43]. The molecular mechanism of transrepression described for in vitro systems is dependent on the presence of t-RA and is believed to involve direct or indirect protein-protein interactions between retinoid receptors and AP-1 components (jun and fos), and/or competition between retinoid receptors and AP-1 for a common factor (or factors) required for their activities [42, 43]. However, this phenomenon studied in the context of photoaging of human skin in vivo has revealed a novel mechanism. 

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