Abstract: 【Abstract】 Objective To explore expression patterns of transcription factor TFAP2B in epidermal melanocytes of healthy individuals and vitiligo patients. Methods Lesional tissues were collected from 5 patients confirmedly diagnosed with progressive vitiligo at the Department of Dermatology, Xijing Hospital, Air Force Medical University from January 2020 to December 2022. At the same time, some discarded normal skin tissues were obtained from 5 gender- and age-matched healthy individuals after plastic surgeries. The immortalized healthy human epidermal melanocyte cell line PIG1, the vitiligo epidermal melanocyte cell line PIG3V, and primary human epidermal melanocytes, which were isolated from the discarded foreskin tissues of 3 healthy males after urological surgeries in Xijing Hospital, were cultured in vitro. Tissue immunofluorescence assay was performed to determine the expression and localization of TFAP2B and dopachrome tautomerase （DCT） in healthy skin tissues and vitiligo lesions, and cell immunofluorescence assay and Western blot analysis were conducted to determine the TFAP2B expression in human epidermal melanocytes. Comparisons between two groups were performed using t test, and correlation analysis was performed using Pearson correlation coefficients. Results Tissue immunofluorescence assay showed that TFAP2B was specifically expressed in human epidermal melanocytes and localized in the nuclei. Western blot analysis showed that TFAP2B was strongly expressed in the human epidermal melanocyte cell line PIG1 and primary melanocytes, with the relative expression levels being 0.45 ± 0.05 and 0.36 ± 0.04, respectively. Tissue immunofluorescence analysis showed that the fluorescence intensity of TFAP2B （623 917.5 ± 88 784.0） was significantly and positively correlated with that of DCT （2 232 655.3 ± 588 810.4; r = 0.91, P < 0.001） in human epidermal tissues from 5 healthy controls and 5 vitiligo patients. In addition, the relative fluorescence intensity of TFAP2B in epidermal melanocytes was significantly lower in the vitiligo lesions （0.12 ± 0.05） than in the healthy skin tissues （1, t = 19.35, P < 0.001）. Western blot analysis showed that the relative expression level of TFAP2B was also significantly lower in the PIG3V cells （0.62 ± 0.09） than in the PIG1 cells （1, t = 5.92, P < 0.027）. Conclusions TFAP2B was specifically and highly expressed in human epidermal melanocytes, and its expression level was significantly and positively correlated with that of the melanocyte marker DCT. Additionally, TFAP2B was obviously lowly expressed in the epidermal melanocytes of patients with vitiligo.

Key words: Vitiligo, Melanocytes, Epidermis, Transcription factor AP-2, Dopachrome tautomerase, Expression pattern