1. ¹Department of Dermatology, Seoul National University College of Medicine, Seoul, Korea
2. ²Laboratory of Cutaneous Aging Research, Clinical Research Institute, Seoul National University Hospital, Seoul, Korea
3. ³Institute of Dermatological Science, Seoul National University, Seoul, Korea

Correspondence: Dr Jin H. Chung, Department of Dermatology, Seoul National University Hospital, 28 Yongon-Dong, Chongno-Gu, Seoul 110-744, Korea. E-mail: jhchung@snu.ac.kr

⁴Current address: Department of Dermatology, Peking University People's Hospital, Beijing, China

⁵These authors share senior authorship

Received 13 December 2006; Revised 21 March 2007; Accepted 26 March 2007; Published online 17 May 2007.

Abstract

Transient receptor potential vanilloid-1 (TRPV1), a heat-gated channel, was recently found on human keratinocytes and the activation of epidermal TRPV1 was known to induce release of proinflammatory mediators. However, the functional consequences of TRPV1 activation in cutaneous physiology and pathology have not been elucidated clearly. In this study, we investigated the role of TRPV1 on the matrix metalloproteinase (MMP)-1 expression induced by heat shock in human epidermal keratinocytes. Heat shock induced the expression of MMP-1 mRNA and protein in a temperature-dependent manner in an immortalized human keratinocyte cell line (HaCaT) and normal human epidermal keratinocytes (NHK). Heat-shock-induced MMP-1 expression was decreased by treatment of the TRPV1 inhibitors (capsazepine and ruthenium red) or knockdown of TRPV1 using RNA interference in HaCaT cells. Overexpression of TRPV1 greatly increased heat-shock-induced MMP-1 promoter activity in HEK 293 cells. Furthermore, direct activation of TRPV1 by capsaicin, a TRPV1 agonist, increased MMP-1 expression. We found that heat shock induced calcium influx through TRPV1 and that extracellular calcium was necessary for heat-shock-induced MMP-1 expression in HaCaT cells. Taken together, our results suggest that heat-shock-induced MMP-1 expression is mediated by activation of TRPV1 and is dependent on a calcium-dependent signaling process in human epidermal keratinocytes.