Regulation of cuticle pigmentation in drosophila by the nutrient sensing insulin and TOR signaling pathways

• Published in: Developmental dynamics 2014-03, Vol.243 (3), p.393-401
• Main Authors: Shakhmantsir, Iryna, Massad, Nicole L., Kennell, Jennifer A.
• Format: Article
• Language: English
• Subjects: Akt; Animals; Drosophila melanogaster; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; Female; FOXO; Insulin - genetics; Insulin - metabolism; Male; melanin; Oncogene Protein v-akt - genetics; Oncogene Protein v-akt - metabolism; phenotypic plasticity; Phosphatidylinositol 3-Kinases - genetics; Phosphatidylinositol 3-Kinases - metabolism; PI3K; Pigmentation - physiology; Signal Transduction - physiology; TOR Serine-Threonine Kinases - genetics; TOR Serine-Threonine Kinases - metabolism; TSC2
• ISSN: 1058-8388; 1097-0177
• DOI: 10.1002/dvdy.24080

Background: Insect pigmentation is a phenotypically plastic trait that plays a role in thermoregulation, desiccation tolerance, mimicry, and sexual selection. The extent and pattern of pigmentation of the abdomen and thorax in Drosophila melanogaster is affected by environmental factors such a growth temperature and access to the substrates necessary for melanin biosynthesis. This study aimed to determine the effect of nutritional status during development on adult pigmentation and test whether nutrient sensing through the Insulin/IGF and target of rapamycin (TOR) pathways regulates the melanization of adult cuticle in Drosophila. Results: Flies reared on low quality food exhibit decreased pigmentation, which can be phenocopied by inhibiting expression of the Insulin receptor (InR) throughout the entire fly during mid to late pupation. The loss of Insulin signaling through PI3K/Akt and FOXO in the epidermis underlying the developing adult cuticle causes a similar decrease in adult pigmentation, suggesting that Insulin signaling acts in a cell autonomous manner to regulate cuticle melanization. In addition, TOR signaling increases pigmentation in a cell autonomous manner, most likely through increased S6K activity. Conclusion: These results suggest that nutrient sensing through the Insulin/IGF and TOR pathways couples cuticle pigmentation of both male and female Drosophila with their nutritional status during metamorphosis. Developmental Dynamics 243:393–401, 2014. © 2013 Wiley Periodicals, Inc. Key findings Nutritional status during pupation regulates adult cuticle pigmentation in Drosophila melanogaster. Insulin signaling in the underlying epidermal cells positively regulates cuticle pigmentation through PI3K/Akt and FOXO. TOR signaling through S6K is a positive regulator of cuticle melanization.