ZFIN Image: Praetorius et al., 2013, Fig. 3

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Figure Caption

Fig. 3

Intron 4 of IRF4 Drives Expression in Melanocytes

(A and B) Results of the luciferase assays in melan-Ink4a-Arf and SK-MEL-28 cells are shown. Pr, promoter; Luc, luciferase reporter gene; IRF4 enh, 450 bp fragment from the fourth intron of IRF4 containing rs12203592. “IRF4 enh” fragments are identical except for the base at position rs12203592 as indicated (“C” is the ancestral allele; “T” is the derived allele). The x axis shows fold luciferase activity relative to the minimal promoter alone, which is normalized to one (1). p values are calculated by Kolmogorov-Smirnov test. The result is also highly significant by other nonparametric tests (p = 0.007937 by Wilcoxon rank sum test for both melan-Ink4a-Arf and SK-MEL-28) and by the standard parametric t test (p = 0.001686 for melan-Ink4a-Arf; p = 0.01032 for SK-MEL-28). Each bar represents the average of five biological replicates per reporter construct. Error bars represent SD.

(C) Reporter constructs contain either the rs12203592-C version of the IRF4 intron 4 element (IRF4) or the rs12203592-T version (IRF4snp) upstream of the GFP reporter after injection into zebrafish. The numbers represent the number of melanophores (blue) and embryos (red) seen to be positive (pos.) for GFP. The difference between the melanophores containing the wild-type allele of intron 4 of IRF4 compared to the mutant allele (rs12203592) is statistically significant (p = 0.0023, unpaired t test).

(D) Image shows a GFP-positive zebrafish embryo with a GFP-positive melanophore in the inset.

Acknowledgments

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Reprinted from Cell, 155(5), Praetorius, C., Grill, C., Stacey, S.N., Metcalf, A.M., Gorkin, D.U., Robinson, K.C., Van Otterloo, E., Kim, R.S., Bergsteinsdottir, K., Ogmundsdottir, M.H., Magnusdottir, E., Mishra, P.J., Davis, S.R., Guo, T., Zaidi, M.R., Helgason, A.S., Sigurdsson, M.I., Meltzer, P.S., Merlino, G., Petit, V., Larue, L., Loftus, S.K., Adams, D.R., Sobhiafshar, U., Emre, N.C., Pavan, W.J., Cornell, R., Smith, A.G., McCallion, A.S., Fisher, D.E., Stefansson, K., Sturm, R.A., and Steingrimsson, E., A Polymorphism in IRF4 Affects Human Pigmentation through a Tyrosinase-Dependent MITF/TFAP2A Pathway, 1022-1033, Copyright (2013) with permission from Elsevier. Full text @ Cell