Dynamic bi-directional phosphorylation events associated with the reciprocal regulation of synapses during homeostatic up- and down-scaling

• Published in: Cell reports (Cambridge) Vol. 36; no. 8; p. 109583
• Main Authors: Desch, Kristina, Langer, Julian D., Schuman, Erin M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 24.08.2021; Cell Press; Elsevier
• Subjects: Animals; Chromatography, Liquid - methods; Excitatory Postsynaptic Potentials - physiology; Homeostasis - physiology; homeostatic scaling; mass spectrometry; Neuronal Plasticity - physiology; Neurons - metabolism; phosphoproteomics; Phosphorylation; post-translational modification; protein phosphorylation; proteomics; PTM; Receptors, AMPA - metabolism; Resource; Synapses - metabolism; synaptic plasticity; phosphoproteomics; proteomics; PTM; mass spectrometry; synaptic plasticity; homeostatic scaling; post-translational modification; protein phosphorylation
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2021.109583

Homeostatic synaptic scaling allows for bi-directional adjustment of the strength of synaptic connections in response to changes in their input. Protein phosphorylation modulates many neuronal processes, but it has not been studied on a global scale during synaptic scaling. Here, we use liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses to measure changes in the phosphoproteome in response to up- or down-scaling in cultured cortical neurons over minutes to 24 h. Of ~45,000 phosphorylation events, ~3,300 (associated with 1,285 phosphoproteins) are regulated by homeostatic scaling. Activity-sensitive phosphoproteins are predominantly located at synapses and involved in cytoskeletal reorganization. We identify many early phosphorylation events that could serve as sensors for the activity offset as well as late and/or persistent phosphoregulation that could represent effector mechanisms driving the homeostatic response. Much of the persistent phosphorylation is reciprocally regulated by up- or down-scaling, suggesting that mechanisms underlying these two poles of synaptic regulation make use of a common signaling axis. [Display omitted] •Global proteome and phosphoproteome dynamics following homeostatic synaptic scaling•Approximately 3,300 activity-sensitive, synapse-associated phospho-events•Persistent signaling of ~25% of initial phospho-events (min to 24 h)•Persistent and reciprocal phosphoregulation links synaptic up- and down-scaling Using LC-MS/MS, Desch et al. investigate protein phosphorylation as an additional layer of regulation shaping homeostatic synaptic scaling. Characterizing the temporal dynamics of activity-sensitive phosphorylation, they detect potential sensor and/or effector events for up- and down-scaling. They find sustained and reciprocal phosphorylation patterns, which mechanistically couple the opposing scaling phenotypes.