N-Acetylglucosamine suppress collagenases activation in ultraviolet B-irradiated human dermal fibroblasts: Involvement of calcium ions and mitogen-activated protein kinases Yong Pil Hwang a , Hyung Gyun Kim a , Eun Hee Han a , Jae Ho Choi a , Bong Hwan Park a , Kyung Hwa Jung b , Young Chul Shin b , Hye Gwang Jeong a, * a Department of Toxicology, College of Pharmacy, Chungnam National University, Daejeon 305-764, Republic of Korea b Amicogen, Inc., Jinju, Republic of Korea 1. Introduction Skin aging can be attributed to extrinsic and intrinsic (chronological) processes that are commonly manifested by increased wrinkling, sagging, and laxity [1,2]. Ultraviolet (UV) irradiation causes distinct changes in skin collagenous tissues as a result of the breakdown of collagen, a major component of the extracellular matrix [3–5]. Exposure of skin to UVA, and occasionally UVB, induces the intracellular generation of large quantities of reactive oxygen species (ROS). ROS-induced molecu- lar damage produces a number of harmful effects on cellular function and homeostasis, while degradation of extracellular matrix (ECM) proteins, such as collagen, by ROS can cause major changes in skin connective tissue [4,5]. UV-induced ROS can lead to skin damage including skin cancer, autoimmune disease and inflammation while induced matrix metalloproteinases (MMPs) expression can cause collagen degradation [6]. These alterations in the ECM, most likely mediated by MMPs, are known to be a cause of the skin wrinkling that characterizes premature skin aging and aged skin [7]. MMPs are a family of zinc-dependent endopeptidases that include MMP-1 (interstitial collagenase), MMP-3 (stromelysin-1) and MMP-9 (92 kDa type IV gelatinase). These enzymes play key roles not only in the degradation of the basement membrane and ECM but also in the expression of inflammatory cytokines [8]. In particular, MMP-1 is mainly responsible for the degradation of dermal collagen during the aging process of human skin [9]. Recently, it was suggested that excessive matrix degradation by UV-induced MMP-1 secreted by various cells (e.g., keratinocytes and fibroblasts cells) contributes substantially to the connective Journal of Dermatological Science 63 (2011) 93–103 A R T I C L E I N F O Article history: Received 21 January 2011 Received in revised form 31 March 2011 Accepted 11 April 2011 Keywords: N-Acetylglucosamine Ultraviolet B Human skin fibroblasts Matrix metalloproteinases Collagen Photoaging S U M M A R Y Background: N-Acetylglucosamine (GlcNAc) and its derivates have been utilized in dietary supplements and for therapeutic development due to their unique characteristics. GlcNAc is recognized primarily for its function as a precursor to hyaluronic acid, which plays a significant role in the structure and hydration of the extracellular matrix in skin, in both the epidermis and the dermis. Objective: We investigated the protective effects of GlcNAc on immortalized human skin fibroblasts (HS68) against UVB damage. We then explored the inhibitory effects of GlcNAc on UVB-induced collagenases and investigated the molecular mechanism underlying those effects. Methods: Those effects were assessed by semi-quantitative PCR, Western blotting and enzymatic activity assays. Results: GlcNAc increased the viability of, and inhibited ROS production in, HS68 cells exposed to UVB irradiation. Pre-treatment of HS68 cells with GlcNAc inhibited UVB-induced production of the collagenases MMP-1 and MMP-13. Western blot analysis further revealed that GlcNAc markedly suppressed the enhancement of collagen degradation in UVB-exposed HS68 cells. GlcNAc also suppressed UVB-induced activation of c-Jun, c-Fos and NF-kB and the phosphorylation of MAPKs and PI3K/Akt, upstream modulators of AP-1 and NF-kB. Moreover, GlcNAc decreased the UVB-induced influx of Ca 2+ into HS68 cells and the phosphorylation of Ca 2+ /calmodulin-dependent kinases (CaMKs). Conclusion: The results indicate that GlcNAc inhibited UVB-induced collagenolytic MMP production by interfering with Ca 2+ -dependent Akt and MAPKs/AP-1 and NF-kB signaling. They may thus be potentially useful in the prevention and treatment of skin photoaging. ß 2011 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved. * Corresponding author. Tel.: +82 42 821 5936. E-mail address: hgjeong@cnu.ac.kr (H.G. Jeong). Contents lists available at ScienceDirect Journal of Dermatological Science jou r nal h o mep ag e: w ww .elsevier .co m /jds 0923-1811/$36.00 ß 2011 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.jdermsci.2011.04.008