Endogenous plasma membrane t-SNARE syntaxin 4 is present in rab11 positive endosomal membranes and associates with cortical actin cytoskeleton

We characterized the yeast actin cytoskeleton at the ultrastructural level using immunoelectron microscopy. Anti-actin antibodies primarily labeled dense, patchlike cortical structures and cytoplasmic cables. This localization recapitulates results obtained with immunofluorescence light microscopy, but at much higher resolution. Immuno-EM double-labeling experiments were conducted with antibodies to actin together with antibodies to the actin binding proteins Abp1p and cofilin. As expected from immunofluorescence experiments, Abp1p, cofilin, and actin colocalized in immuno-EM to the dense patchlike structures but not to the cables. In this way, we can unambiguously identify the patches as the cortical actin cytoskeleton. The cortical actin patches were observed to be associated with the cell surface via an invagination of plasma membrane. This novel cortical cytoskeleton-plasma membrane interface appears to consist of a fingerlike invagination of plasma membrane around which actin filaments and actin binding proteins are organized. We propose a possible role for this unique cortical structure in wall growth and osmotic regulation.

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Actin Cytoskeletal Dynamics in Single-Cell Wound Repair

International Journal of Molecular Sciences ◽

10.3390/ijms221910886 ◽

2021 ◽

Vol 22 (19) ◽

pp. 10886

Author(s):

Malene Laage Ebstrup ◽

Catarina Dias ◽

Anne Sofie Busk Heitmann ◽

Stine Lauritzen Sønder ◽

Jesper Nylandsted

Keyword(s):

Plasma Membrane ◽

Actin Cytoskeleton ◽

Single Cell ◽

Wound Repair ◽

Membrane Integrity ◽

Limited Attention ◽

Membrane Repair ◽

Cortical Actin ◽

Comprehensive Overview ◽

Repair Mechanisms

The plasma membrane protects the eukaryotic cell from its surroundings and is essential for cell viability; thus, it is crucial that membrane disruptions are repaired quickly to prevent immediate dyshomeostasis and cell death. Accordingly, cells have developed efficient repair mechanisms to rapidly reseal ruptures and reestablish membrane integrity. The cortical actin cytoskeleton plays an instrumental role in both plasma membrane resealing and restructuring in response to damage. Actin directly aids membrane repair or indirectly assists auxiliary repair mechanisms. Studies investigating single-cell wound repair have often focused on the recruitment and activation of specialized repair machinery, despite the undeniable need for rapid and dynamic cortical actin modulation; thus, the role of the cortical actin cytoskeleton during wound repair has received limited attention. This review aims to provide a comprehensive overview of membrane repair mechanisms directly or indirectly involving cortical actin cytoskeletal remodeling.

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Plasma Membrane-associated Annexin A6 Reduces Ca2+Entry by Stabilizing the Cortical Actin Cytoskeleton

Journal of Biological Chemistry ◽

10.1074/jbc.m109.004457 ◽

2009 ◽

Vol 284 (25) ◽

pp. 17227-17242 ◽

Cited By ~ 49

Author(s):

Katia Monastyrskaya ◽

Eduard B. Babiychuk ◽

Andrea Hostettler ◽

Peta Wood ◽

Thomas Grewal ◽

...

Keyword(s):

Plasma Membrane ◽

Actin Cytoskeleton ◽

Cortical Actin

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AFM sensing cortical actin cytoskeleton destabilization during plasma membrane electropermeabilization

Cytoskeleton ◽

10.1002/cm.21194 ◽

2014 ◽

Vol 71 (10) ◽

pp. 587-594 ◽

Cited By ~ 14

Author(s):

Chopinet Louise ◽

Dague Etienne ◽

Rols Marie-Pierre

Keyword(s):

Plasma Membrane ◽

Actin Cytoskeleton ◽

Cortical Actin

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Regulation of the Actin Cytoskeleton-Plasma Membrane Interplay by Phosphoinositides

Physiological Reviews ◽

10.1152/physrev.00036.2009 ◽

2010 ◽

Vol 90 (1) ◽

pp. 259-289 ◽

Cited By ~ 297

Author(s):

Juha Saarikangas ◽

Hongxia Zhao ◽

Pekka Lappalainen

Keyword(s):

Plasma Membrane ◽

Actin Cytoskeleton ◽

Actin Dynamics ◽

Actin Binding ◽

Cell Physiology ◽

Cortical Actin ◽

Bar Domain ◽

Pathogen Invasion ◽

Associated Proteins ◽

Continuous Dynamic

The plasma membrane and the underlying cortical actin cytoskeleton undergo continuous dynamic interplay that is responsible for many essential aspects of cell physiology. Polymerization of actin filaments against cellular membranes provides the force for a number of cellular processes such as migration, morphogenesis, and endocytosis. Plasma membrane phosphoinositides (especially phosphatidylinositol bis- and trisphosphates) play a central role in regulating the organization and dynamics of the actin cytoskeleton by acting as platforms for protein recruitment, by triggering signaling cascades, and by directly regulating the activities of actin-binding proteins. Furthermore, a number of actin-associated proteins, such as BAR domain proteins, are capable of directly deforming phosphoinositide-rich membranes to induce plasma membrane protrusions or invaginations. Recent studies have also provided evidence that the actin cytoskeleton-plasma membrane interactions are misregulated in a number of pathological conditions such as cancer and during pathogen invasion. Here, we summarize the wealth of knowledge on how the cortical actin cytoskeleton is regulated by phosphoinositides during various cell biological processes. We also discuss the mechanisms by which interplay between actin dynamics and certain membrane deforming proteins regulate the morphology of the plasma membrane.

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Sla2p Is Associated with the Yeast Cortical Actin Cytoskeleton via Redundant Localization Signals

Molecular Biology of the Cell ◽

10.1091/mbc.10.7.2265 ◽

1999 ◽

Vol 10 (7) ◽

pp. 2265-2283 ◽

Cited By ~ 70

Author(s):

Shirley Yang ◽

M. Jamie T. V. Cope ◽

David G. Drubin

Keyword(s):

Plasma Membrane ◽

Actin Cytoskeleton ◽

Coiled Coil ◽

Intramolecular Interactions ◽

The Other ◽

Actin Binding ◽

Filamentous Actin ◽

Cortical Actin ◽

C Terminus

Sla2p, also known as End4p and Mop2p, is the founding member of a widely conserved family of actin-binding proteins, a distinguishing feature of which is a C-terminal region homologous to the C terminus of talin. These proteins may function in actin cytoskeleton-mediated plasma membrane remodeling. A human homologue of Sla2p binds to huntingtin, the protein whose mutation results in Huntington’s disease. Here we establish by immunolocalization that Sla2p is a component of the yeast cortical actin cytoskeleton. Deletion analysis showed that Sla2p contains two separable regions, which can mediate association with the cortical actin cytoskeleton, and which can provide Sla2p function. One localization signal is actin based, whereas the other signal is independent of filamentous actin. Biochemical analysis showed that Sla2p exists as a dimer in vivo. Two-hybrid analysis revealed two intramolecular interactions mediated by coiled-coil domains. One of these interactions appears to underlie dimer formation. The other appears to contribute to the regulation of Sla2p distribution between the cytoplasm and plasma membrane. The data presented are used to develop a model for Sla2p regulation and interactions.

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Cofilin, But Not Profilin, Is Required for Myosin-I-Induced Actin Polymerization and the Endocytic Uptake in Yeast

Molecular Biology of the Cell ◽

10.1091/mbc.02-04-0052 ◽

2002 ◽

Vol 13 (11) ◽

pp. 4074-4087 ◽

Cited By ~ 22

Author(s):

Fatima-Zahra Idrissi ◽

Bianka L. Wolf ◽

M. Isabel Geli

Keyword(s):

Plasma Membrane ◽

Fluorescence Microscopy ◽

Actin Cytoskeleton ◽

Actin Filaments ◽

Actin Polymerization ◽

Cortical Actin ◽

Myosin I ◽

Robust Evidence

Mutations in the budding yeast myosins-I (MYO3 andMYO5) cause defects in the actin cytoskeleton and in the endocytic uptake. Robust evidence also indicates that these proteins induce Arp2/3-dependent actin polymerization. Consistently, we have recently demonstrated, using fluorescence microscopy, that Myo5p is able to induce cytosol-dependent actin polymerization on the surface of Sepharose beads. Strikingly, we now observed that, at short incubation times, Myo5p induced the formation of actin foci that resembled the yeast cortical actin patches, a plasma membrane-associated structure that might be involved in the endocytic uptake. Analysis of the machinery required for the formation of the Myo5p-induced actin patches in vitro demonstrated that the Arp2/3 complex was necessary but not sufficient in the assay. In addition, we found that cofilin was directly involved in the process. Strikingly though, the cofilin requirement seemed to be independent of its ability to disassemble actin filaments and profilin, a protein that closely cooperates with cofilin to maintain a rapid actin filament turnover, was not needed in the assay. In agreement with these observations, we found that like the Arp2/3 complex and the myosins-I, cofilin was essential for the endocytic uptake in vivo, whereas profilin was dispensable.

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The PtdIns3P-binding protein Phafin2 escorts macropinosomes through the cortical actin cytoskeleton

10.1101/180760 ◽

2017 ◽

Cited By ~ 3

Author(s):

Kay Oliver Schink ◽

Kia Wee Tan ◽

Hélène Spangenberg ◽

Domenica Martorana ◽

Marte Sneeggen ◽

...

Keyword(s):

Plasma Membrane ◽

Actin Cytoskeleton ◽

Binding Protein ◽

Extracellular Fluid ◽

Cancer Development ◽

Cross Linking ◽

Filamin A ◽

Actin Network ◽

Cortical Actin ◽

Cell Centre

AbstractUptake of large volumes of extracellular fluid by actin-dependent macropinocytosis plays important roles in infection, immunity and cancer development. A key question is how large macropinosomes are able to squeeze through the dense actin network underlying the plasma membrane in order to move towards the cell centre for maturation. Here we show that, immediately after macropinosomes have been sealed off from the plasma membrane, the PH-and FYVE domain-containing protein Phafin2 is recruited by a mechanism that involves binding to phosphatidylinositol 3-phosphate (PtdIns3P) generated in a non-canonical manner. Phafin2 in turn regulates the actin cross-linking protein Filamin A to promote entry of macropinosomes through the subcortical actin matrix and subsequent maturation. Depletion of Phafin2 inhibits macropinocytic internalization and maturation. We conclude that PtdIns3P and its effector Phafin2 are key components of a system that allows nascent macropinosomes to navigate through the dense subcortical actin network.

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Dynamic cortical actin remodeling by ERM proteins controls BCR microcluster organization and integrity

Journal of Experimental Medicine ◽

10.1084/jem.20101125 ◽

2011 ◽

Vol 208 (5) ◽

pp. 1055-1068 ◽

Cited By ~ 123

Author(s):

Bebhinn Treanor ◽

David Depoil ◽

Andreas Bruckbauer ◽

Facundo D. Batista

Keyword(s):

Actin Cytoskeleton ◽

B Cell ◽

Protein Function ◽

Actin Polymerization ◽

Lymphocyte Activation ◽

Dominant Negative ◽

Temporary Increase ◽

Cortical Actin ◽

Erm Proteins ◽

Diffusion Dynamics

Signaling microclusters are a common feature of lymphocyte activation. However, the mechanisms controlling the size and organization of these discrete structures are poorly understood. The Ezrin-Radixin-Moesin (ERM) proteins, which link plasma membrane proteins with the actin cytoskeleton and regulate the steady-state diffusion dynamics of the B cell receptor (BCR), are transiently dephosphorylated upon antigen receptor stimulation. In this study, we show that the ERM proteins ezrin and moesin influence the organization and integrity of BCR microclusters. BCR-driven inactivation of ERM proteins is accompanied by a temporary increase in BCR diffusion, followed by BCR immobilization. Disruption of ERM protein function using dominant-negative or constitutively active ezrin constructs or knockdown of ezrin and moesin expression quantitatively and qualitatively alters BCR microcluster formation, antigen aggregation, and downstream BCR signal transduction. Chemical inhibition of actin polymerization also altered the structure and integrity of BCR microclusters. Together, these findings highlight a crucial role for the cortical actin cytoskeleton during B cell spreading and microcluster formation and function.

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