Cytoskeleton in Platelet Function

Lewis, Jon C.

doi:10.1007/978-1-4684-4592-3_10

Cited by 4 publications

(4 citation statements)

References 78 publications

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“…This nucleation differs from the nucleating activity of capping proteins (Cooper and Pollard, 1985;Coue and Korn, 1985;Weber et al, 1987), since both ends of membraneassociated nuclei will be free. This mechanism, which is analogous to previous theoretical proposals (Edelman, 1976;Brandts and Jacobson, 1983), could explain how external signals trigger large increases in actin polymerization during capping (Laub et al, 1981), chemotaxis (reviewed in Newell, 1986;Omann et al, 1987), phagocytosis (Painter and Mclntosh, 1979), secretion (Pfeiffer et al, 1985), and cell shape changes (reviewed in Fox and Phillips, 1983;Lewis, 1984).…”

Section: A Model For Actin Assembly At Membrane Surfacessupporting

confidence: 77%

“…The close relationship between actin polymerization and actin-membrane binding is of considerable interest since it provides a possible physical basis for the observed coupling between signals generated at the plasma membrane and increases in cytoplasmic F-actin (Painter and Mclntosh, 1979;Laub et al, 1981;Fox and Phillips, 1983;Lewis, 1984;Pfeiffer et al, 1985;Carson et al, 1986;Newell, 1986;Omann et al, 1987). However, the close relationship between actin binding and actin polymerization at membrane surfaces also greatly complicates quantitative analyses of these interactions.…”

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confidence: 99%

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How actin binds and assembles onto plasma membranes from Dictyostelium discoideum.

Schwartz

Luna

1988

The Journal of Cell Biology

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Abstract. We have shown previously (Schwartz, M. A., and E. J. Luna. 1986. J. Cell Biol. 102: 2067-2075.) that actin binds with positive cooperativity to plasma membranes from Dictyostelium discoideum. Actin is polymerized at the membrane surface even at concentrations well below the critical concentration for polymerization in solution. Low salt buffer that blocks actin polymerization in solution also prevents actin binding to membranes. To further explore the relationship between actin polymerization and binding to membranes, we prepared four chemically modified actins that appear to be incapable of polymerizing in solution. Three of these derivatives also lost their ability to bind to membranes. The fourth derivative (EF actin), in which histidine-40 is labeled with ethoxyformic anhydride, binds to membranes with reduced affinity. Binding curves exhibit positive cooperativity, and cross-linking experiments show that membrane-bound actin is multimeric. Thus, binding and polymerization are tightly coupled, and the ability of these membranes to polymerize actin is dramatically demonstrated. EF actin coassembles weakly with untreated actin in solution, but coassembles well on membranes. Binding by untreated actin and EF actin are mutually competitive, indicating that they bind to the same membrane sites. Hill plots indicate that an actin trimer is the minimum assembly state required for tight binding to membranes. The best explanation for our data is a model in which actin oligomers assemble by binding to clustered membrane sites with successive monomers on one side of the actin filament bound to the membrane. Individual binding affinities are expected to be low, but the overall actinmembrane avidity is high, due to multivalency. Our results imply that extracellular factors that cluster membrane proteins may create sites for the formation of actin nuclei and thus trigger actin polymerization in the cell.

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Section: A Model For Actin Assembly At Membrane Surfacessupporting

confidence: 77%

mentioning

confidence: 99%

How actin binds and assembles onto plasma membranes from Dictyostelium discoideum.

Schwartz

Luna

1988

The Journal of Cell Biology

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“…This sequence of adhesion and spreading involves a morphologic change from a disc shape through spherical and several pseudopodial stages and finally culminates in a flattened, circular, fully spread stage. We, and others, have shown with correlative SEM and HVEM that major cytoskeletal reorganization occurs concomitant with this shape change process Albrecht and Lewis, 1982;Goodman et al, 198913;Lewis, 1983Lewis, , 1984Nachmias et al, 1979;White, 1987;Mosher et al, 1985). Briefly, discoid forms have no or little polymerized actin, but do possess a peripheral microtubular band.…”

Section: Introductionmentioning

confidence: 92%

Distribution and movement of membrane‐associated platelet glycoproteins: Use of colloidal gold with correlative video‐enhanced light microscopy, low‐voltage high‐resolution scanning electron microscopy, and high‐voltage transmission electron microscopy

1989

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Scanning electron microscopy (SEM), especially low-voltage (1 KeV) high-resolution SEM, can be used in conjunction with stereo pair high-voltage (1 MeV) transmission electron microscopy (HVEM) of whole spread cells or thick sections effectively to correlate surface structure with internal structure. Surface features such as microvilli, pits, pseudopodia, ruffles, attached virus, and other surface-related morphologic characteristics can be identified using SEM, while underlying cytoskeletal structure and organelle organization can be viewed by HVEM of the same preparation. However, the need to "prepare" cells for electron microscopy precludes observation in the living state. The use of several types of video-enhanced light microscopy (VLM) permits observation of living cells such that certain surface and internal features can be observed at a relatively high level of resolution or detection. Thus, changes in living cells can be followed, and at appropriate times the cells may be chemically fixed or rapidly frozen and prepared for ultrastructural examination by electron microscopy. We have utilized VLM in conjunction with SEM and HVEM to correlate changes in shape and surface structure with changes in the internal structure of platelets. In addition, we have found it advantageous to use colloidal gold-labeling procedures, because these markers are detectable by all three forms of microscopy. Using this approach we have labeled platelet membrane GPIIb/IIIa, a receptor for RGD-containing adhesive proteins, with gold-fibrinogen or gold-anti-IIb/IIIa. The initial binding and subsequent movement of gold-fibrinogen-IIb/IIIa complexes in living platelets was followed by VLM. The movement of individual labels could be mapped. Subsequent observation by low-voltage (1 KeV) high-resolution SEM and HVEM permits visualization of the same individual receptors tracked by LM. The final position on the membrane or the position-in-transit when fixative was added was determined relative to surface ultrastructure (SEM) and internal, particularly cytoskeletal, ultrastructure (HVEM).

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“…Marcel Bessis (Centre Nationale de Transfusion Sanguine, Paris, France) was one of the first who investigated megakaryocytes and PLT among other blood cells ultrastructurally [50,51]. In the following years, fine structural features of PLT have been described, such as the microtubular coil (MTC) providing the discoid shape of nonactivated PLT [40,[52][53][54][55][56][57][58][59][60], the microfilamentous network providing their contractile apparatus [29,53,55,61,62], and the surface-connected open canalicular system (OCS). The latter represents an invagination of the plasma membrane providing a connection with the outer milieu via pores at the surface and a two-way channel for uptake of particles and the delivery of granular contents during activation and degranulation [24,34,35,[63][64][65].…”

Section: Historical Overviewmentioning

confidence: 99%

Transmission Electron Microscopy of Platelets FROM Apheresis and Buffy-Coat-Derived Platelet Concentrates

Neumüller¹,

Ellinger²

2015

The Transmission Electron Microscope - Theory and Applications

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Platelet concentrates are produced in order to treat bleeding disorders. They can be provided by apheresis machines or by pooling of buffy coats from four blood donations. During their manufacturing and storage, morphological alterations of platelets occur which can be demonstrated by transmission electron microscopy. Alterations range from slight and reversible changes, such as formation of small cell protrusions and swelling of the surface-connected open canalicular system, to severe structural changes, where platelets undergo transitions from discoid to ameboid shapes as a consequence of platelet activation. These alterations end in delivery of the contents of platelet granules as well as platelet involution caused by apoptosis and necrosis processes denoted as the platelet release reaction. Hereby, the involvement of the network of the open canalicular system, helping to deliver the contents of platelet granules into the surrounding milieu via pores, is distinctly shown by electron tomography. As a consequence of platelet activation, a delivery of differently sized microparticles takes place which is thought to play an important role in the adverse reactions in some recipients of platelet concentrates. In this article, the formation and delivery of platelet microparticles is illustrated by electron tomography. Above all, the ultrastructural features of platelets and megakaryocytes are discussed in the context of the molecular characteristics of the plasma membrane and organelles including the different granules and the expression of receptors engaged in signaling during platelet activation. Starting from the knowledge of the ultrastructure of resting and activated platelets, a score classification is presented, allowing the evaluation of different activation stages in a reproducible manner. Examples of evaluations of platelet concentrates using electron microscopy are briefly reviewed. In the last part,

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Cytoskeleton in Platelet Function

Cited by 4 publications

References 78 publications

How actin binds and assembles onto plasma membranes from Dictyostelium discoideum.

How actin binds and assembles onto plasma membranes from Dictyostelium discoideum.

Distribution and movement of membrane‐associated platelet glycoproteins: Use of colloidal gold with correlative video‐enhanced light microscopy, low‐voltage high‐resolution scanning electron microscopy, and high‐voltage transmission electron microscopy

Transmission Electron Microscopy of Platelets FROM Apheresis and Buffy-Coat-Derived Platelet Concentrates

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