Dynamic subcellular proteomics identifies novel regulators of adipocyte insulin action

Insulin acts on adipocytes to control whole-body glucose and lipid metabolism by increasing glucose uptake and inhibiting lipolysis. These processes are dependent on changes in protein localisation (e.g GLUT4 translocation to the plasma membrane (PM)). However, our knowledge of spatial proteomic changes in response to insulin is limited. Here, we use subcellular proteomics to map insulin-stimulated protein relocalisation at a cell-wide scale. Approximately 10% of proteins identified exhibited altered subcellular localisation in response to insulin. Since the PM was a major site of insulin-responsive proteome remodelling, we performed additional PM proteome profiling to quantify insulin-responsive changes at the cell surface. These orthologous proteomic approaches revealed insulin-stimulated redistribution of C3ORF18 to the PM. Studies in adipocytes depleted of C3ORF18 suggest this protein is required for maximal insulin signalling. Overall, our data provide an accessible resource of insulin-regulated changes in protein localisation and impetus for further work on how changes in protein localisation contribute to the cellular insulin response.