Abeling of TH in isolated thoraces just prior to the onset of pigmentation, in both wildtype and Rheb overexpressing flies. Pupal bristle purchase INCB-039110 pigmentation is induced in an anterior to posterior wave at stage p10, and TH expression is likewise induced in a small subset of epidermal and mechanosensory bristle cells at the anterior region in control pupae (pannier-Gal4). On the other hand, at this same developmental stage in Rheb overexpressing pupae, the TH expression domain extends to the posterior region of the thorax and TH is expressed in many more cells (Fig. 4B ). Consistent with our previous observations of Rheb induced pigmentation, expansion of the TH expression domain in the Rheb overexpressing flies was suppressed by expression of either raptorRNAi or s6k1RNAi (Fig. 4B ). Elevated TH protein levels could be due to increased transcription, translation, or protein stability. We asked whether Rheb overexpression could promote expression of a lacZ reporter construct, that recapitulates the expression pattern of endogenous TH [23]. In both wildtype and Rheb-overexpressing pupae, the TH lacZ reporter expression pattern was similar to that observed with the TH antibody (Fig. 4F, G), which suggests that Rheb controls TH through either transcription or translation, but is not dependent on the TH coding sequence. Despite the strongTORC1 Controls Drosophila PigmentationFigure 3. TSC1/2 pathway regulates amino acid levels and function upstream of the catecholamine pathway. The Drosophila melanin biosynthesis pathway (modified from (Wittkopp, True and Carroll, 2002) enzymes in blue, substrates in black; phenol oxidases, aaNAT and NADA sclerotin have been excluded) (A). Pigmentation in MARCM clones of tsc1 R453x (B) is partially suppressed in a yellow background (C, arrowheads indicate clone regions in both B and C). Amino acid and metabolite analysis of heads collected from UAS-Rheb/TM3, Sb and elav-Gal4/UAS-Rheb flies, show statistically significant increases in glutamine, ammonia, lysine, 1-methylhistidine, and asparagine under conditions of neuronal Rheboverexpression (Student’s T-test-*, D). UAS-THRNAi markedly suppressed the UAS-Rheb, Peptide M supplier pannier-Gal4 pigmentation phenotype (E). Genotypes of flies: w/yw,Ubx-flp; scabrous-Gal4,UAS-Pon-GFP,UAS-Tau-GFP/+;FRT82B, tsc1R453x/FRT82B tub-Gal80 (B), yw/yw,Ubx-flp; scabrous-Gal4,UAS-Pon-GFP, UAS-TauGFP/+; FRT82B, tsc1R453/FRT82B tub-Gal80 (C), Y/w; UAS-Rheb/TM3, Sb and Y/w; UAS-Rheb/elav-Gal4 (D), Y/w, UAS-dicer2; UAS-Rheb/+; pannier-Gal4/ UAS-THRNAi (E). doi:10.1371/journal.pone.0048720.gincrease in TH protein in isolated thoraces from pannier-Gal4, UAS-Rheb pupae, we did not observe significant increase in tyrosine hydroxylase RNA levels by rtPCR, while Rheb levels showed a three fold increase (Fig. S2F), Taken together, our findings 1527786 indicate that high Rheb activity increases TH expression in epidermal and mechanosensory cells in the pupal thorax.DiscussionOur study demonstrates that high Rheb activity in epidermal cells of the fly results in increased levels of melanin synthesis andpigmentation during pupal development. Rheb-induced hyperpigmentation is TORC1-dependent and appears to be due to increased levels of tyrosine hydroxylase (TH) protein, the ratelimiting enzyme in catecholamine biosynthesis. Adult Drosophila cuticular pigmentation occurs in two steps: in the first, initiated during late pupal stages, melanization genes such as TH, DDC, Yellow and Ebony are expressed in the epidermis and ext.Abeling of TH in isolated thoraces just prior to the onset of pigmentation, in both wildtype and Rheb overexpressing flies. Pupal bristle pigmentation is induced in an anterior to posterior wave at stage p10, and TH expression is likewise induced in a small subset of epidermal and mechanosensory bristle cells at the anterior region in control pupae (pannier-Gal4). On the other hand, at this same developmental stage in Rheb overexpressing pupae, the TH expression domain extends to the posterior region of the thorax and TH is expressed in many more cells (Fig. 4B ). Consistent with our previous observations of Rheb induced pigmentation, expansion of the TH expression domain in the Rheb overexpressing flies was suppressed by expression of either raptorRNAi or s6k1RNAi (Fig. 4B ). Elevated TH protein levels could be due to increased transcription, translation, or protein stability. We asked whether Rheb overexpression could promote expression of a lacZ reporter construct, that recapitulates the expression pattern of endogenous TH [23]. In both wildtype and Rheb-overexpressing pupae, the TH lacZ reporter expression pattern was similar to that observed with the TH antibody (Fig. 4F, G), which suggests that Rheb controls TH through either transcription or translation, but is not dependent on the TH coding sequence. Despite the strongTORC1 Controls Drosophila PigmentationFigure 3. TSC1/2 pathway regulates amino acid levels and function upstream of the catecholamine pathway. The Drosophila melanin biosynthesis pathway (modified from (Wittkopp, True and Carroll, 2002) enzymes in blue, substrates in black; phenol oxidases, aaNAT and NADA sclerotin have been excluded) (A). Pigmentation in MARCM clones of tsc1 R453x (B) is partially suppressed in a yellow background (C, arrowheads indicate clone regions in both B and C). Amino acid and metabolite analysis of heads collected from UAS-Rheb/TM3, Sb and elav-Gal4/UAS-Rheb flies, show statistically significant increases in glutamine, ammonia, lysine, 1-methylhistidine, and asparagine under conditions of neuronal Rheboverexpression (Student’s T-test-*, D). UAS-THRNAi markedly suppressed the UAS-Rheb, pannier-Gal4 pigmentation phenotype (E). Genotypes of flies: w/yw,Ubx-flp; scabrous-Gal4,UAS-Pon-GFP,UAS-Tau-GFP/+;FRT82B, tsc1R453x/FRT82B tub-Gal80 (B), yw/yw,Ubx-flp; scabrous-Gal4,UAS-Pon-GFP, UAS-TauGFP/+; FRT82B, tsc1R453/FRT82B tub-Gal80 (C), Y/w; UAS-Rheb/TM3, Sb and Y/w; UAS-Rheb/elav-Gal4 (D), Y/w, UAS-dicer2; UAS-Rheb/+; pannier-Gal4/ UAS-THRNAi (E). doi:10.1371/journal.pone.0048720.gincrease in TH protein in isolated thoraces from pannier-Gal4, UAS-Rheb pupae, we did not observe significant increase in tyrosine hydroxylase RNA levels by rtPCR, while Rheb levels showed a three fold increase (Fig. S2F), Taken together, our findings 1527786 indicate that high Rheb activity increases TH expression in epidermal and mechanosensory cells in the pupal thorax.DiscussionOur study demonstrates that high Rheb activity in epidermal cells of the fly results in increased levels of melanin synthesis andpigmentation during pupal development. Rheb-induced hyperpigmentation is TORC1-dependent and appears to be due to increased levels of tyrosine hydroxylase (TH) protein, the ratelimiting enzyme in catecholamine biosynthesis. Adult Drosophila cuticular pigmentation occurs in two steps: in the first, initiated during late pupal stages, melanization genes such as TH, DDC, Yellow and Ebony are expressed in the epidermis and ext.
