The insulin signalling network.

Insulin signalling is a central regulator of metabolism, orchestrating nutrient homeostasis and coordinating carbohydrate, protein and lipid metabolism. This network operates through dynamic, tightly regulated protein phosphorylation events involving key kinases such as AKT, shaping cellular responses with remarkable precision. Advances in phosphoproteomics have expanded our understanding of insulin signalling, revealing its intricate regulation and links to disease, particularly cardiometabolic disease. Major insights, such as the mechanisms of AKT activation and the influence of genetic and environmental factors, have emerged from studying this network. In this Review, we examine the architecture of insulin signalling, focusing on its precise temporal regulation. We highlight AKT's central role in insulin action and its vast substrate repertoire, which governs diverse cellular functions. Additionally, we explore feedback and crosstalk mechanisms, such as insulin receptor substrate protein signalling, which integrates inputs through phosphorylation at hundreds of distinct sites. Crucially, phosphoproteomics has uncovered complexities in insulin-resistant states, where network rewiring is characterized by disrupted phosphorylation and the emergence of novel sites that are absent in healthy cells. These insights redefine insulin signalling and its dysfunction, highlighting new therapeutic opportunities.