From sensory organs to internal pathways: A comprehensive review of amino acid sensing in Drosophila

Organisms require various nutrients to provide energy, support growth, and maintain metabolic balance. Amino acid is among the most basic nutrients, serving as fundamental building blocks for protein synthesis while playing vital roles in growth, development, and reproduction. Understanding the mechanisms by which organisms perceive amino acids is key to unraveling how they select appropriate food sources and adapt to environmental challenges. The fruit fly, Drosophila melanogaster, serves as a powerful model for understanding fundamental genetic and physiological processes. This review focuses on recent advances in amino acid sensing mechanisms in Drosophila melanogaster and their relevance to feeding behavior, nutrient homeostasis, and adaptive responses, and integrates insights into peripheral sensory systems, such as the legs and proboscis, as well as internal regulatory mechanisms within the gut, fat body, and brain. It highlights key molecular players, including ionotropic receptors, gut-derived hormones, neuropeptides, and the microbiome-gut-brain axis. Additionally, the manuscript identifies knowledge gaps and proposes directions for future research, providing a comprehensive overview of this dynamic field.