Abstract: HOU Mai-hua*, LU Xin-zheng, Peter M Elias. *Department of Dermatology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China Corresponding author: HOU Mai-hua, Email: houmh71@yahoo.com.cn 【Abstract】 Objective To compare the expression of caspase 14 in keratinocytes from people of different skin color, and to evaluate the effect of melanocytes and/or melanin on the expression of caspase 14. Methods Epidermal keratinocytes and melanocytes were isolated from the foreskin of fair- and dark-skinned neonates, and subjected to a primary culture. The second-passage keratinocytes were divided into 6 groups to be cultured with or without the presence of melanocytes from individuals with fair or dark skin at a ratio of 10 ∶ 1 for 24 hours. Western blot was performed to measure the expression of caspase 14 in these keratinocytes. The difference in caspase 14 expression between keratinocytes receiving different treatment was assessed by t test and analysis of variance （ANOVA）. Results The expression of caspase 14 was significantly higher in keratinocytes from dark-skinned（Fitzpatrick skin type Ⅳ/Ⅴ） individuals than in fair-skinned （Fitzpatrick skin typeⅠ/Ⅱ） individuals（P ＜ 0.01）. The coculture with melanocytes elevated the expression of caspase 14 in second-passage keratinocytes, and the elevation was statistically significant in keratinocytes from dark-skinned individuals cocultured with melanocytes from dark-skinned individuals （P < 0.05）, but insignificant in keratinocytes from fair-skinned individuals cocultured with melanocytes from dark- or fair-skinned individuals or in keratinocytes from dark-skinned individuals cocultured with melanocytes from fair-skinned individuals （all P > 0.05）. Conclusions The expression of caspase 14 is higher in keratinocytes from dark-skinned individuals than in those from fair-skinned individuals, and melanocytes can enhance the expression of caspase 14 in keratinocytes from dark-skinned individuals. 【Key words】 Melanocytes; Keratinocytes; Caspase 14; Persons; Skin color

Key words: HaCaT, human, skin colour