Brain-wide measurement of protein turnover with high spatial and temporal resolution

Abstract

Cellular functions are regulated by synthesizing and degrading proteins. This results in protein turnover on time scales ranging from minutes to weeks, varying across proteins, cellular compartments, cell types, and tissues. Current methods to track protein turnover lack the spatial and temporal resolution needed to investigate these processes, especially in the intact brain, which presents unique pharmacokinetic challenges. We describe a pulse-chase method (DELTA) to measure protein turnover with high spatial and temporal resolution throughout the body, including the brain. DELTA relies on the rapid covalent capture by HaloTag of fluorophores that were optimized for bioavailabilityin vivo. The nuclear protein MeCP2 showed brain region- and cell type-specific turnover. The synaptic protein PSD95 was shown to be destabilized in specific brain regions by behavioral enrichment. A novel variant of expansion microscopy enabled turnover measurements at individual synapses. DELTA will enable studies of adaptive and maladaptive plasticity in brain-wide neural circuits.