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Updated: Jul 26, 2025

Single-molecule Super-resolution Imaging of Phosphatidylinositol 4,5-bisphosphate in the Plasma Membrane with Novel Fluorescent Probes
Published on: October 15, 2016
Phosphatidylinositol 4-kinase IIα is a glycogen synthase kinase 3-regulated interaction hub for activity-dependent
Eva-Maria Blumrich1, Jessica C Nicholson-Fish2, Marie Pronot1
1Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, Scotland EH8 9XD, UK; Muir Maxwell Epilepsy Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, Scotland EH8 9XD, UK; Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, Scotland EH8 9XD, UK.
Abstract:
Phosphatidylinositol 4-kinase IIα (PI4KIIα) generates essential phospholipids and is a cargo for endosomal adaptor proteins. Activity-dependent bulk endocytosis (ADBE) is the dominant synaptic vesicle endocytosis mode during high neuronal activity and is sustained by glycogen synthase kinase 3β (GSK3β) activity. We reveal the GSK3β substrate PI4KIIα is essential for ADBE via its depletion in primary neuronal cultures. Kinase-dead PI4KIIα rescues ADBE in these neurons but not a phosphomimetic form mutated at the GSK3β site, Ser-47. Ser-47 phosphomimetic peptides inhibit ADBE in a dominant-negative manner, confirming that Ser-47 phosphorylation is essential for ADBE. Phosphomimetic PI4KIIα interacts with a specific cohort of presynaptic molecules, two of which, AGAP2 and CAMKV, are also essential for ADBE when depleted in neurons. Thus, PI4KIIα is a GSK3β-dependent interaction hub that silos essential ADBE molecules for liberation during neuronal activity.
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