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. Author manuscript; available in PMC: 2014 Mar 1.
Published in final edited form as: Exp Dermatol. 2013 Mar;22(3):202–209. doi: 10.1111/exd.12099

Figure 1. 9-cis retinal is the ALDH1A1 substrate that stimulates melanogenesis.

Figure 1

(A) The ALDH1A inhibitor cyanamide inhibits TYR and MITF mRNA accumulation. MNT-1 melanoma cells were treated with the indicated doses of cyanamide for 24 hours and the relative expression of TYR and MITF mRNA was quantified as described in the methods. (B) The ALDH1A inhibitor Angeli’s salt inhibits TYR and MITF mRNA accumulation. MNT-1 melanoma cells were treated with the indicated doses of Angeli’s salt for 24 hours and the relative expression of TYR and MITF mRNA was quantified as described in the methods. (C) 4-HNE is not sufficient to induce the accumulation of either TYR or MITF mRNA. MNT-1 melanoma cells were treated with the indicated doses of 4-HNE for 24 hours, and TYR and MITF mRNA expression was quantified as described in the methods. (D) In conjunction with UVA radiation, 9-cis retinal induces the accumulation of both TYR and MITF mRNA. MNT-1 melanoma cells were pre-incubated with 9-cis retinal at the indicated concentrations for 45 minutes before being irradiated with UVA light as indicated. Relative mRNA expression was quantified as described in the methods. All data shown are mean ± S.D. (n=3 as indicated by the error bars). *, p < 0.05 or **, p < 0.01 using a Student’s paired t-test with a two-tailed normal distribution versus vehicle-treated control. (E) Melanin accumulation is induced by 9-cis retinal in conjunction with UVA radiation. MNT-1 melanoma cells were treated with the indicated doses of 9-cis retinal, irradiated with UVA, and then allowed to reach confluency. Melanin accumulation was measured as described in the methods section. Data shown are mean ± S.D. (n=6 as indicated by the error bars). *, p < 0.05 or **, p < 0.01 using a Student’s paired t-test with a two-tailed normal distribution versus vehicle-treated control.