Long-term depression in neurons involves temporal and ultra-structural dynamics of phosphatidylinositol-4,5-bisphosphate relying on PIP5K, PTEN and PLC

Synaptic plasticity involves proper establishment and rearrangement of structural and functional microdomains. Yet, visualization of the underlying lipid cues proved challenging. Applying a combination of rapid cryofixation, membrane freeze-fracturing, immunogold labeling and electron microscopy, we visualize and quantitatively determine the changes and the distribution of phosphatidylinositol-4,5-bisphosphate (PIP(2)) in the plasma membrane of dendritic spines and subareas thereof at ultra-high resolution. These efforts unravel distinct phases of PIP(2) signals during induction of long-term depression (LTD). During the first minutes PIP(2) rapidly increases in a PIP5K-dependent manner forming nanoclusters. PTEN contributes to a second phase of PIP(2) accumulation. The transiently increased PIP(2) signals are restricted to upper and middle spine heads. Finally, PLC-dependent PIP(2) degradation provides timely termination of PIP(2) cues during LTD induction. Together, this work unravels the spatial and temporal cues set by PIP(2) during different phases after LTD induction and dissects the molecular mechanisms underlying the observed PIP(2) dynamics.