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

2017 ◽  
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.

scholarly journals The phosphoinositide coincidence detector Phafin2 promotes macropinocytosis by coordinating actin organisation at forming macropinosomes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kay Oliver Schink ◽  
Kia Wee Tan ◽  
Hélène Spangenberg ◽  
Domenica Martorana ◽  
Marte Sneeggen ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Extracellular Fluid ◽  
Coincidence Detection ◽  
Cancer Development ◽  
Actin Assembly ◽  
Actin Network ◽  
Ph Domain ◽  
Actin Reorganization ◽  
Domain Protein ◽  
Pass Through

AbstractUptake of large volumes of extracellular fluid by actin-dependent macropinocytosis has an important role in infection, immunity and cancer development. A key question is how actin assembly and disassembly are coordinated around macropinosomes to allow them to form and subsequently pass through the dense actin network underlying the plasma membrane to move towards the cell center for maturation. Here we show that the PH and FYVE domain protein Phafin2 is recruited transiently to newly-formed macropinosomes by a mechanism that involves coincidence detection of PtdIns3P and PtdIns4P. Phafin2 also interacts with actin via its PH domain, and recruitment of Phafin2 coincides with actin reorganization around nascent macropinosomes. Moreover, forced relocalization of Phafin2 to the plasma membrane causes rearrangement of the subcortical actin cytoskeleton. Depletion of Phafin2 inhibits macropinosome internalization and maturation and prevents KRAS-transformed cancer cells from utilizing extracellular protein as an amino acid source. We conclude that Phafin2 promotes macropinocytosis by controlling timely delamination of actin from nascent macropinosomes for their navigation through the dense subcortical actin network.

scholarly journals Ultrastructure of the yeast actin cytoskeleton and its association with the plasma membrane.

1994 ◽  
Vol 125 (2) ◽  
pp. 381-391 ◽  
Author(s):  
J Mulholland ◽  
D Preuss ◽  
A Moon ◽  
A Wong ◽  
D Drubin ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Binding Proteins ◽  
Ultrastructural Level ◽  
Actin Binding ◽  
Cortical Actin ◽  
Actin Binding Proteins ◽  
Double Labeling ◽  
Wall Growth ◽  
Cortical 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.

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

FEBS Letters ◽  
2002 ◽  
Vol 531 (3) ◽  
pp. 513-519 ◽  
Author(s):  
Arja M Band ◽  
Heidi Ali ◽  
Maria K Vartiainen ◽  
Saara Welti ◽  
Pekka Lappalainen ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Cortical Actin ◽  
Endosomal Membranes ◽  
Syntaxin 4

scholarly journals Actin Cytoskeletal Dynamics in Single-Cell Wound Repair

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.

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

2009 ◽  
Vol 284 (25) ◽  
pp. 17227-17242 ◽  
Author(s):  
Katia Monastyrskaya ◽  
Eduard B. Babiychuk ◽  
Andrea Hostettler ◽  
Peta Wood ◽  
Thomas Grewal ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Cortical Actin

scholarly journals ATP depletion: a novel method to study junctional properties in epithelial tissues. I. Rearrangement of the actin cytoskeleton

1994 ◽  
Vol 107 (12) ◽  
pp. 3301-3313 ◽  
Author(s):  
R. Bacallao ◽  
A. Garfinkel ◽  
S. Monke ◽  
G. Zampighi ◽  
L.J. Mandel
Keyword(s):  
Tight Junction ◽  
Actin Cytoskeleton ◽  
Three Dimensional ◽  
Atp Depletion ◽  
Ultrastructural Changes ◽  
Junctional Complex ◽  
Actin Network ◽  
Cortical Actin ◽  
Actin Ring ◽  
Dimensional Reconstruction

The effect of cellular injury caused by depletion of intracellular ATP stores was studied in the Madin-Darby canine kidney (MDCK) and JTC cell lines. In prior studies, it was shown that ATP depletion uncouples the gate and fence functions of the tight junction. This paper extends these observations by studying the changes in the actin cytoskeleton and tight junction using electron microscopy and confocal fluorescence microscopy in combination with computer-aided three-dimensional reconstruction. Marked regional differences in the sensitivity to the effects of ATP depletion were observed in the actin cytoskeleton. Actin depolymerization appears to first affect the cortical actin network running along the apical basal axis of the cell. The next actin network that is disrupted is the stress fibers found at the basal surface of the cell. Finally, the actin ring at the level of the zonulae occludens and adherens is compromised. The breakup of the actin ring correlates with ultrastructural changes in tight junction strands and the loss of the tight junction's role as a molecular fence. During the process of actin network dissolution, polymerized actin aggregates form in the cytoplasm. The changes in the junctional complexes and the potential to reverse the ATP depletion suggest that this may be a useful method to study junctional complex formation and its relationship to the actin cytoskeletal network.

scholarly journals Disruption of the Actin Cytoskeleton Can Complement the Ability of Nef To Enhance Human Immunodeficiency Virus Type 1 Infectivity

2004 ◽  
Vol 78 (11) ◽  
pp. 5745-5755 ◽  
Author(s):  
Edward M. Campbell ◽  
Rafael Nunez ◽  
Thomas J. Hope
Keyword(s):  
Human Immunodeficiency Virus ◽  
Actin Cytoskeleton ◽  
Leukemia Virus ◽  
Actin Network ◽  
Cortical Actin ◽  
Immunodeficiency Virus ◽  
Cytoskeleton Disruption ◽  
Amphotropic Envelope ◽  
Cytoskeleton Rearrangements

ABSTRACT The human immunodeficiency virus (HIV) protein Nef has been shown to increase the infectivity of HIV at an early point during infection. Since Nef is known to interact with proteins involved in actin cytoskeleton rearrangements, we tested the possibility that Nef may enhance HIV infectivity via a mechanism that involves the actin cytoskeleton. We find that disruption of the actin cytoskeleton complements the Nef infectivity defect. The ability of disruption of the actin cytoskeleton to complement the Nef defect was specific to envelopes that fuse at the cell surface, including a variety of HIV envelopes and the murine leukemia virus amphotropic envelope. In contrast, the infectivity of HIV virions pseudotyped to enter cells via endocytosis, which is known to complement the HIV Nef infectivity defect and can naturally penetrate the cortical actin barrier, was not altered by actin cytoskeleton disruption. The results presented here suggest that Nef functions to allow the HIV genome to penetrate the cortical actin network, a known barrier for intracellular parasitic organisms.

AFM sensing cortical actin cytoskeleton destabilization during plasma membrane electropermeabilization

Cytoskeleton ◽  
2014 ◽  
Vol 71 (10) ◽  
pp. 587-594 ◽  
Author(s):  
Chopinet Louise ◽  
Dague Etienne ◽  
Rols Marie-Pierre
Keyword(s):  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Cortical Actin

scholarly journals Filamin A mediates isotropic distribution of applied force across the actin network

2019 ◽  
Vol 218 (8) ◽  
pp. 2481-2491 ◽  
Author(s):  
Abhishek Kumar ◽  
Maria S. Shutova ◽  
Keiichiro Tanaka ◽  
Daniel V. Iwamoto ◽  
David A. Calderwood ◽  
...  
Keyword(s):  
Mechanical Strain ◽  
Focal Adhesions ◽  
High Resolution Electron Microscopy ◽  
Filamin A ◽  
Actin Network ◽  
Force Transmission ◽  
Cortical Actin ◽  
Isotropic Distribution ◽  
Elastic Substrates ◽  
Applied Forces

Cell sensing of externally applied mechanical strain through integrin-mediated adhesions is critical in development and physiology of muscle, lung, tendon, and arteries, among others. We examined the effects of strain on force transmission through the essential cytoskeletal linker talin. Using a fluorescence-based talin tension sensor (TS), we found that uniaxial stretch of cells on elastic substrates increased tension on talin, which was unexpectedly independent of the orientation of the focal adhesions relative to the direction of strain. High-resolution electron microscopy of the actin cytoskeleton revealed that stress fibers (SFs) are integrated into an isotropic network of cortical actin filaments in which filamin A (FlnA) localizes preferentially to points of intersection between SFs and cortical actin. Knockdown (KD) of FlnA resulted in more isolated, less integrated SFs. After FlnA KD, tension on talin was polarized in the direction of stretch, while FlnA reexpression restored tensional symmetry. These data demonstrate that a FlnA-dependent cortical actin network distributes applied forces over the entire cytoskeleton–matrix interface.

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