Regulation of actin dynamics by phosphoinositides: Focus on postsynaptic plasticity.

Phosphoinositides, most prominently phosphatidylinositol (4,5)-bisphosphate and phosphatidylinositol (3,4,5)-trisphosphate, regulate the activities of a wide range of proteins that control the polymerization, depolymerization, and branching of actin filaments. This phosphoinositide-mediated remodeling of the actin cytoskeleton is crucial for a many cellular functions, including migration, division, and intracellular organelle transport. As a unifying theme in this review, we have chosen to focus on the role of phosphoinositides in regulating actin dynamics during dendritic spine plasticity. As in other biological systems, actin polymerization and branching drive morphological changes in dendritic spines by exerting force on the plasma membrane, creating structures such as filopodial protrusions and bulbous spine heads. Activity-dependent changes in the number, size, and shape of dendritic spines underlie fundamental brain functions such as learning and memory and are often disrupted in cognitive and neurological disorders. Hence, the control of actin regulatory proteins in dendritic spines by phosphoinositides has been, and remains, an extremely active area of investigation.