Abstract
A calorie-rich diet is one reason for the continuous spread of metabolic syndromes in western societies. Smart food design is one powerful tool to prevent metabolic stress, and the search for suitable bioactive additives is a continuous task. The nutrient-sensing insulin pathway is an evolutionary conserved mechanism that plays an important role in metabolism, growth and development. Recently, lipid cues capable to stimulate insulin signaling were identified. However, the mechanistic base of their activity remains obscure to date. We show that specific Akt/Protein-kinase B isoforms are responsive to different calorie-rich diets, and potentiate the activity of the cellular insulin cascade. Our data add a new dimension to existing models and position Drosophila as a powerful tool to study the relation between dietary lipid cues and the insulin-induced cellular signal pathway.
Highlights
Food composition is instructive for the metabolic response of organisms and recent studies demonstrate an important role of lipid cues including dietary lipids in modulating systemic insulin signaling
We speculate that lipid cues derived from stationary S. cerevisiae stimulate the accumulation of PI(3,4,5)P3 at the inner plasma-membrane leaflet of Drosophila cells. dAkt85 binds to PI(3,4,5)P3 and as such is accessible for the phosphoinositide-dependent Protein kinase 1 (PDK1) or the Rictor-mammalian target of rapamycin complex 2 (Cho et al, 2001; Sarbassov et al, 2005)
Fly poo positioned on plant food at 20◦C contained C. oligophagum; but not S. cerevisiae, which is the preferred yeast used in experimental Drosophila research
Summary
Food composition is instructive for the metabolic response of organisms and recent studies demonstrate an important role of lipid cues including dietary lipids in modulating systemic insulin signaling. The identity and mechanism of such metabolically active lipids remains obscure; their regulating function is restricted to calorie-rich nutritional settings and is second to the role of sugars (Migrenne et al, 2006; Oh et al, 2010; Brankatschk et al, 2014). It was shown that a calorie-rich diet supplemented with yeast lipids increases circulating Drosophila insulin-like peptides (dILPs) and facilitates high systemic insulin signaling levels (Brankatschk et al, 2014). Compared to baker’s yeast (Saccharomyces cerevisiae), C. oligophagum produce similar amounts of protein and sugar but differ in their lipid composition. Calorie-rich food based on either yeast type supports the generative cycle of Drosophila; only diet manufactured from stationary S. cerevisiae accelerates its developmental rate and increases egg production. We speculate that lipid cues derived from stationary S. cerevisiae stimulate the accumulation of PI(3,4,5)P3 at the inner plasma-membrane leaflet of Drosophila cells. dAkt binds to PI(3,4,5)P3 and as such is accessible for the phosphoinositide-dependent Protein kinase 1 (PDK1) or the Rictor-mammalian target of rapamycin complex 2 (mTorC2) (Cho et al, 2001; Sarbassov et al, 2005)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
