(A) Human FOXN3 and zebrafish Foxn3 orthologs are shown with the central DNA-binding Forkhead Box (nearly invariant amino-acyl residues 112-204) and length marked (to the right). The percent identity of the zebrafish amino-terminus, Forkhead Box and carboxy-terminus relative to human FOXN3 is shown. The conserved Sin3-binding signature (EAA within the carboxy-terminus) is marked. Putative phosphorylation sites found in five or more published phospho-proteomic surveys are shown, as well: the significance of these residues’ phosphorylation has not been established in any organism.
(B) A non-transgenic (wild-type, WT) 7 days post-fertilization larva and two transgenic larvae were photographed in light- and green fluorescent channels in the left-lateral view. The Tg(fabp10a:foxn3,EGFP)z106 transgenic line over-expresses zebrafish foxn3 and EGFP and the Tg(fabp10a:FOXN3,EGFP)z107 transgenic line over-expresses human FOXN3 and EGFP (transcript variant –T003). The encoded EGFP protein is translated as a free (not as a fusion) protein (Provost et al., 2007). Bar 500 μm.
(C, D) pck1 promoter activity (bioluminescence derived from assay of Luciferase; AU, arbitrary units) in lysates prepared from 5 and 6 days post-fertilization (dpf), never-fed Tg(pck1:Luc2,cryaa:mCherry)s952, Tg(fabp10a: foxn3,EGFP)z106; Tg(pck1:Luc2,cryaa:mCherry)s952 and Tg(fabp10a:FOXN3,EGFP)z107; and Tg(pck1:Luc2,cryaa:mCherry)s952 larvae. P <0.02; two-tailed Student’s t-test. n = 5-7.
(E,F) Whole body glucose levels in 6 dpf wild-type (WT), Tg(fabp10a: foxn3,EGFP)z106 and Tg(fabp10a:FOXN3,EGFP)z107larval extracts. *P < 0.02; two-tailed Student’s t-test. n = 4-5 pooled samples of 10 larvae each. All values are mean ± s. e. m.
(G, H), Fasting blood glucose levels in WT, Tg(fabp10a: foxn3,EGFP)z106 and Tg(fabp10a:FOXN3,EGFP)z107 transgenic adult animals of both sexes after an overnight fast.*P = 0.01; 2-tailed t Student’s t-test. n = 9-13.