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Int. J. Mol. Sci. 2015, 16(10), 25096-25107;

Silkworm Thorn Stem Extract Targets RSK2 and Suppresses Solar UV-Induced Cyclooxygenase-2 Expression

WCU Biomodulation Major, Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University, Seoul 151-921, Korea
The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
Advanced Institutes of Convergence Technology, Seoul National University, Suwon 443-270, Korea
Author to whom correspondence should be addressed.
Academic Editor: Charles Brennan
Received: 17 July 2015 / Revised: 30 September 2015 / Accepted: 10 October 2015 / Published: 22 October 2015
(This article belongs to the Section Biochemistry)
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Excessive exposure to solar UV (sUV) is associated with numerous human skin disorders, such as carcinogenesis, skin photoaging and skin inflammation. Silkworm Thorn (Cudraniatricuspidata, SW) is a plant belonging to the Moraceae family and widely present throughout Korea, China, and Japan. Most parts of the tree (including the fruit, leaf, stem, root, and bark) is consumable as a functional food or tea. In this study, we found that SW extract (SWE) inhibited the elevated expression of sUV-induced cyclooxygenase (COX)-2 levels in both HaCaT and JB6 cells. Levels of nuclear factor-κB and activator protein-1, two crucial transcription factors involved in COX-2 expression, were elevated by sUV treatment. Treatment with SWE abolished this activation. SWE also inhibited sUV-induced histone H3 phosphorylation. However, sUV-induced phosphorylation of Akt, c-Jun N-terminal kinase and p38 kinase remained unchanged in the presence of SWE. SWE inhibited RSK2 activity, and pull-down assays using SWE-Sepharose beads revealed that SWE binds directly with RSK2 in an ATP-competitive manner. These results suggest a potential for SWE to be developed as a cosmeceutical material and functional food constituent for the promotion of skin health. View Full-Text
Keywords: silkworm thorn; cyclooxygenase-2; ultraviolet; RSK2 silkworm thorn; cyclooxygenase-2; ultraviolet; RSK2

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Kim, J.-E.; Lee, K.W. Silkworm Thorn Stem Extract Targets RSK2 and Suppresses Solar UV-Induced Cyclooxygenase-2 Expression. Int. J. Mol. Sci. 2015, 16, 25096-25107.

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