scholarly journals Control of actin polymerization via the coincidence of phosphoinositides and high membrane curvature

2017 ◽  
Vol 216 (11) ◽  
pp. 3745-3765 ◽  
Author(s):  
Frederic Daste ◽  
Astrid Walrant ◽  
Mikkel R. Holst ◽  
Jonathan R. Gadsby ◽  
Julia Mason ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Actin Polymerization ◽  
Kinase Inhibitors ◽  
Mammalian Cell Culture ◽  
Membrane Curvature ◽  
Coated Pits ◽  
Bar Domain ◽  
Oculocerebrorenal Syndrome ◽  
Cascade Amplification ◽  
Hydrolysis Of

The conditional use of actin during clathrin-mediated endocytosis in mammalian cells suggests that the cell controls whether and how actin is used. Using a combination of biochemical reconstitution and mammalian cell culture, we elucidate a mechanism by which the coincidence of PI(4,5)P2 and PI(3)P in a curved vesicle triggers actin polymerization. At clathrin-coated pits, PI(3)P is produced by the INPP4A hydrolysis of PI(3,4)P2, and this is necessary for actin-driven endocytosis. Both Cdc42⋅guanosine triphosphate and SNX9 activate N-WASP–WIP- and Arp2/3-mediated actin nucleation. Membrane curvature, PI(4,5)P2, and PI(3)P signals are needed for SNX9 assembly via its PX–BAR domain, whereas signaling through Cdc42 is activated by PI(4,5)P2 alone. INPP4A activity is stimulated by high membrane curvature and synergizes with SNX9 BAR domain binding in a process we call curvature cascade amplification. We show that the SNX9-driven actin comets that arise on human disease–associated oculocerebrorenal syndrome of Lowe (OCRL) deficiencies are reduced by inhibiting PI(3)P production, suggesting PI(3)P kinase inhibitors as a therapeutic strategy in Lowe syndrome.

scholarly journals Dynamic recruitment of the curvature-sensitive protein ArhGAP44 to nanoscale membrane deformations limits exploratory filopodia initiation in neurons

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Milos Galic ◽  
Feng-Chiao Tsai ◽  
Sean R Collins ◽  
Maja Matis ◽  
Samuel Bandara ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Neuronal Development ◽  
Membrane Curvature ◽  
Gtp Hydrolysis ◽  
Bar Domain ◽  
Curvature Sensing ◽  
Contractile Forces ◽  
Dendritic Branches ◽  
Membrane Deformations ◽  
Protein Recruitment

In the vertebrate central nervous system, exploratory filopodia transiently form on dendritic branches to sample the neuronal environment and initiate new trans-neuronal contacts. While much is known about the molecules that control filopodia extension and subsequent maturation into functional synapses, the mechanisms that regulate initiation of these dynamic, actin-rich structures have remained elusive. Here, we find that filopodia initiation is suppressed by recruitment of ArhGAP44 to actin-patches that seed filopodia. Recruitment is mediated by binding of a membrane curvature-sensing ArhGAP44 N-BAR domain to plasma membrane sections that were deformed inward by acto-myosin mediated contractile forces. A GAP domain in ArhGAP44 triggers local Rac-GTP hydrolysis, thus reducing actin polymerization required for filopodia formation. Additionally, ArhGAP44 expression increases during neuronal development, concurrent with a decrease in the rate of filopodia formation. Together, our data reveals a local auto-regulatory mechanism that limits initiation of filopodia via protein recruitment to nanoscale membrane deformations.

scholarly journals Regulation of membrane scission in yeast endocytosis

2021 ◽  
Author(s):  
Deepikaa Menon ◽  
Marko Kaksonen
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mammalian Cells ◽  
Genetic Manipulation ◽  
Sh3 Domain ◽  
Membrane Curvature ◽  
Yeast Cells ◽  
Vesicle Formation ◽  
Type I ◽  
Bar Domain ◽  
Membrane Scission

During clathrin-mediated endocytosis, a flat plasma membrane is shaped into an invagination that undergoes scission to form a vesicle. In mammalian cells, the force that drives the transition from invagination to vesicle is primarily provided by the GTPase dynamin that acts in concert with crescent-shaped BAR domain proteins. In yeast cells, the mechanism of endocytic scission is unclear. The yeast BAR domain protein complex Rvs161/167 (Rvs) nevertheless plays an important role in this process: deletion of Rvs dramatically reduces scission efficiency. A mechanistic understanding of the influence of Rvs on scission however, remains incomplete. We used quantitative live-cell imaging and genetic manipulation to understand the recruitment and function of Rvs and other late-stage proteins at yeast endocytic sites. We found that arrival of Rvs at endocytic sites is timed by interaction of its BAR domain with specific membrane curvature. A second domain of Rvs167- the SH3 domain- affects localization efficiency of Rvs. We show that Myo3, one of the two type-I myosins in Saccharomyces cerevisiae, has a role in recruiting Rvs167 via the SH3 domain. Removal of the SH3 domain also affects assembly and disassembly of actin and impedes membrane invagination. Our results indicate that both BAR and SH3 domains are important for the role of Rvs as a regulator of scission. We tested other proteins implicated in vesicle formation in Saccharomyces cerevisiae , and found that neither synaptojanins nor dynamin contribute directly to membrane scission. We propose that recruitment of Rvs BAR domains delays scission and allows invaginations to grow by stabilizing them. We also propose that vesicle formation is dependent on the force exerted by the actin network component of the endocytic machinery.

scholarly journals Missing-in-metastasis and IRSp53 deform PI(4,5)P2-rich membranes by an inverse BAR domain–like mechanism

2007 ◽  
Vol 176 (7) ◽  
pp. 953-964 ◽  
Author(s):  
Pieta K. Mattila ◽  
Anette Pykäläinen ◽  
Juha Saarikangas ◽  
Ville O. Paavilainen ◽  
Helena Vihinen ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Membrane Curvature ◽  
Membrane Dynamics ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Tubular Structures ◽  
Membrane Deformation ◽  
Bar Domain ◽  
Membrane Protrusions ◽  
Induce Plasma

The actin cytoskeleton plays a fundamental role in various motile and morphogenetic processes involving membrane dynamics. We show that actin-binding proteins MIM (missing-in-metastasis) and IRSp53 directly bind PI(4,5)P2-rich membranes and deform them into tubular structures. This activity resides in the N-terminal IRSp53/MIM domain (IMD) of these proteins, which is structurally related to membrane-tubulating BAR (Bin/amphiphysin/Rvs) domains. We found that because of a difference in the geometry of the PI(4,5)P2-binding site, IMDs induce a membrane curvature opposite that of BAR domains and deform membranes by binding to the interior of the tubule. This explains why IMD proteins induce plasma membrane protrusions rather than invaginations. We also provide evidence that the membrane-deforming activity of IMDs, instead of the previously proposed F-actin–bundling or GTPase-binding activities, is critical for the induction of the filopodia/microspikes in cultured mammalian cells. Together, these data reveal that interplay between actin dynamics and a novel membrane-deformation activity promotes cell motility and morphogenesis.

scholarly journals Functional Entry of Baculovirus into Insect and Mammalian Cells Is Dependent on Clathrin-Mediated Endocytosis

2006 ◽  
Vol 80 (17) ◽  
pp. 8830-8833 ◽  
Author(s):  
Gang Long ◽  
Xiaoyu Pan ◽  
Richard Kormelink ◽  
Just M. Vlak
Keyword(s):  
Electron Microscopy ◽  
Mammalian Cells ◽  
Low Ph ◽  
Coated Pits ◽  
Immuno Electron Microscopy ◽  
Endocytosis Pathway ◽  
Ph Dependent ◽  
Budded Virus

ABSTRACT Entry of the budded virus form of baculoviruses into insect and mammalian cells is generally thought to occur through a low-pH-dependent endocytosis pathway, possibly through clathrin-coated pits. This insight is primarily based on (immuno)electron microscopy studies but requires biochemical support to exclude the use of other pathways. Here, we demonstrate using various inhibitors that functional entry of baculoviruses into insect and mammalian cells is primarily dependent on clathrin-mediated endocytosis. Our results further suggest that caveolae are somehow involved in baculovirus entry in mammalian cells. A caveolar endocytosis inhibitor, genistein, enhances baculovirus transduction in these cells considerably.

scholarly journals Phosphatidylinositol-(4,5)-bisphosphate regulates clathrin-coated pit initiation, stabilization, and size

2011 ◽  
Vol 22 (14) ◽  
pp. 2588-2600 ◽  
Author(s):  
Costin N. Antonescu ◽  
François Aguet ◽  
Gaudenz Danuser ◽  
Sandra L. Schmid
Keyword(s):  
Mammalian Cells ◽  
Lipid Binding ◽  
Coated Pits ◽  
Inositol Phosphatase ◽  
Major Mechanism ◽  
Synaptojanin 1 ◽  
Phosphatidylinositol 4 ◽  
Sirna Knockdown ◽  
Interfering Rna ◽  
Pit Initiation

Clathrin-mediated endocytosis (CME) is the major mechanism for internalization in mammalian cells. CME initiates by recruitment of adaptors and clathrin to form clathrin-coated pits (CCPs). Nearly half of nascent CCPs abort, whereas others are stabilized by unknown mechanisms and undergo further maturation before pinching off to form clathrin-coated vesicles (CCVs). Phosphatidylinositol-(4,5)-bisphosphate (PIP2), the main lipid binding partner of endocytic proteins, is required for CCP assembly, but little is currently known about its contribution(s) to later events in CCV formation. Using small interfering RNA (siRNA) knockdown and overexpression, we have analyzed the effects of manipulating PIP2 synthesis and turnover on CME by quantitative total internal reflection fluorescence microscopy and computational analysis. Phosphatidylinositol-4-phosphate-5-kinase cannot be detected within CCPs but functions in initiation and controls the rate and extent of CCP growth. In contrast, the 5′-inositol phosphatase synaptojanin 1 localizes to CCPs and controls early stabilization and maturation efficiency. Together these results suggest that the balance of PIP2 synthesis in the bulk plasma membrane and its local turnover within CCPs control multiple stages of CCV formation.

scholarly journals FAM92A1 is a BAR domain protein required for mitochondrial ultrastructure and function

2018 ◽  
Vol 218 (1) ◽  
pp. 97-111 ◽  
Author(s):  
Liang Wang ◽  
Ziyi Yan ◽  
Helena Vihinen ◽  
Ove Eriksson ◽  
Weihuan Wang ◽  
...  
Keyword(s):  
Mitochondrial Function ◽  
Molecular Mechanisms ◽  
Membrane Curvature ◽  
Mitochondrial Morphology ◽  
Membrane Remodeling ◽  
Mitochondrial Ultrastructure ◽  
Bar Domain ◽  
Bar Domain Proteins ◽  
Domain Protein

Mitochondrial function is closely linked to its dynamic membrane ultrastructure. The mitochondrial inner membrane (MIM) can form extensive membrane invaginations known as cristae, which contain the respiratory chain and ATP synthase for oxidative phosphorylation. The molecular mechanisms regulating mitochondrial ultrastructure remain poorly understood. The Bin-Amphiphysin-Rvs (BAR) domain proteins are central regulators of diverse cellular processes related to membrane remodeling and dynamics. Whether BAR domain proteins are involved in sculpting membranes in specific submitochondrial compartments is largely unknown. In this study, we report FAM92A1 as a novel BAR domain protein localizes to the matrix side of the MIM. Loss of FAM92A1 caused a severe disruption to mitochondrial morphology and ultrastructure, impairing organelle bioenergetics. Furthermore, FAM92A1 displayed a membrane-remodeling activity in vitro, inducing a high degree of membrane curvature. Collectively, our findings uncover a role for a BAR domain protein as a critical organizer of the mitochondrial ultrastructure that is indispensable for mitochondrial function.

scholarly journals Drosophila F-BAR protein Syndapin contributes to coupling the plasma membrane and contractile ring in cytokinesis

Open Biology ◽  
2013 ◽  
Vol 3 (8) ◽  
pp. 130081 ◽  
Author(s):  
Tetsuya Takeda ◽  
Iain M. Robinson ◽  
Matthew M. Savoian ◽  
John R. Griffiths ◽  
Anthony D. Whetton ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Curvature ◽  
Cellular Process ◽  
Cleavage Furrow ◽  
Contractile Ring ◽  
Functional Interaction ◽  
Cortical Dynamics ◽  
Central Spindle ◽  
Bar Domain ◽  
Spindle Microtubules

Cytokinesis is a highly ordered cellular process driven by interactions between central spindle microtubules and the actomyosin contractile ring linked to the dynamic remodelling of the plasma membrane. The mechanisms responsible for reorganizing the plasma membrane at the cell equator and its coupling to the contractile ring in cytokinesis are poorly understood. We report here that Syndapin, a protein containing an F-BAR domain required for membrane curvature, contributes to the remodelling of the plasma membrane around the contractile ring for cytokinesis. Syndapin colocalizes with phosphatidylinositol 4,5-bisphosphate (PI(4,5)P 2 ) at the cleavage furrow, where it directly interacts with a contractile ring component, Anillin. Accordingly, Anillin is mislocalized during cytokinesis in Syndapin mutants. Elevated or diminished expression of Syndapin leads to cytokinesis defects with abnormal cortical dynamics. The minimal segment of Syndapin, which is able to localize to the cleavage furrow and induce cytokinesis defects, is the F-BAR domain and its immediate C-terminal sequences. Phosphorylation of this region prevents this functional interaction, resulting in reduced ability of Syndapin to bind to and deform membranes. Thus, the dephosphorylated form of Syndapin mediates both remodelling of the plasma membrane and its proper coupling to the cytokinetic machinery.

scholarly journals The eisosome core is composed of BAR domain proteins

2011 ◽  
Vol 22 (13) ◽  
pp. 2360-2372 ◽  
Author(s):  
Agustina Olivera-Couto ◽  
Martin Graña ◽  
Laura Harispe ◽  
Pablo S. Aguilar
Keyword(s):  
Plasma Membrane ◽  
Mammalian Cells ◽  
Site Directed Mutagenesis ◽  
Bar Domain ◽  
Macromolecular Assemblies ◽  
Surface Patches ◽  
Cytoplasmic Proteins ◽  
Associated Proteins ◽  
Core Components ◽  
Membrane Bending

Eisosomes define sites of plasma membrane organization. In Saccharomyces cerevisiae, eisosomes delimit furrow-like plasma membrane invaginations that concentrate sterols, transporters, and signaling molecules. Eisosomes are static macromolecular assemblies composed of cytoplasmic proteins, most of which have no known function. In this study, we used a bioinformatics approach to analyze a set of 20 eisosome proteins. We found that the core components of eisosomes, paralogue proteins Pil1 and Lsp1, are distant homologues of membrane-sculpting Bin/amphiphysin/Rvs (BAR) proteins. Consistent with this finding, purified recombinant Pil1 and Lsp1 tubulated liposomes and formed tubules when the proteins were overexpressed in mammalian cells. Structural homology modeling and site-directed mutagenesis indicate that Pil1 positively charged surface patches are needed for membrane binding and liposome tubulation. Pil1 BAR domain mutants were defective in both eisosome assembly and plasma membrane domain organization. In addition, we found that eisosome-associated proteins Slm1 and Slm2 have F-BAR domains and that these domains are needed for targeting to furrow-like plasma membrane invaginations. Our results support a model in which BAR domain protein–mediated membrane bending leads to clustering of lipids and proteins within the plasma membrane.

Sign in / Sign up

Export Citation Format

Share Document