title: The initiation of post-synaptic protrusions.
abstract: The post-synaptic spines of neuronal dendrites are highly elaborate membrane protrusions. Their anatomy, stability and density are intimately linked to cognitive performance. The morphological transitions of spines are powered by coordinated polymerization of actin filaments against the plasma membrane, but how the membrane-associated polymerization is spatially and temporally regulated has remained ill defined. Here, we discuss our recent findings showing that dendritic spines can be initiated by direct membrane bending by the I-BAR protein MIM/Mtss1. This lipid phosphatidylinositol (PI(4,5)P2) signaling-activated membrane bending coordinated spatial actin assembly and promoted spine formation. From recent advances, we formulate a general model to discuss how spatially concentrated protein-lipid microdomains formed by multivalent interactions between lipids and actin/membrane regulatory proteins might launch cell protrusions.
authors.affiliation: Neuroscience Center, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland.
authors.forename: Pirta
authors.initials: P
authors.lastname: Hotulainen
authors.affiliation: Institute of Biochemistry , ETH Zurich, Switzerland.
authors.forename: Juha
authors.initials: J
authors.lastname: Saarikangas
keywords: Arp2/3 complex; actin cytoskeleton; filopodia; lipid demixing; membrane deformation