Ultrastructural analysis of platelets in nonhuman primates

Lewis, Jon C.; White, Melanie S.; Prater, T; Taylor, Richard G.; Davis, Katie S

doi:10.1016/0014-4800(82)90049-1

Cited by 18 publications

(4 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By 30 rnin at 26°C the platelets were partially spread and by 60 min the platelets spread into flattened triangles, polygons, or disc-like shapes with diameters averaging about 7-8 pm as shown in earlier studies [Lewis et al, 1982;Loftus and Albrecht, 1984;Behnke and Bray, 19881. Figure 1 shows that strong phosphorylation of the 47 kDa and weaker phosphorylation of the 20 kDa polypeptide (myosin regulatory light chain) occurred after 5 min expo-sure to the surface and remained at about the same level for 20 min with a slight decrease by 30 min.…”

Section: Spreading and Activationmentioning

confidence: 75%

See 1 more Smart Citation

Vinculin in relation to stress fibers in spread platelets

Nachmias

Golla

1991

Cell Motil. Cytoskeleton

View full text Add to dashboard Cite

To investigate the function of vinculin in blood platelets, we studied its localization in relation to other cytoskeletal proteins as well as its state of phosphorylation in platelets allowed to spread on fibrinogen-coated surfaces. By 5 minutes after loading the platelets onto the surfaces the 47 and 20 kDa polypeptides became phosphorylated, indicating activation. By 30 minutes, platelets formed small, typical bundles of fibers which stained brilliantly with rhodamine phalloidin. Myosin and tropomyosin, detected with specific antibodies, were localized in periodic arrays along these bundles. By indirect immunofluorescence, a discrete patch of vinculin was observed at each end of every actin-containing bundle. Vinculin phosphorylation was not detected in immunoprecipitates protected against phosphatases. Interference reflection images showed that regions of close binding to the substratum (adhesion plaques) closely matched the vinculin staining sites. Talin appeared diffusely localized. It could be shown to be present in the plaques when platelets were stabilized with ZnCl2 by the method of Geiger and then sonicated to remove some of the surface membrane. Localizations of vinculin and myosin were unaltered by this treatment. Talin phosphorylation or proteolysis could not account for vinculin translocation. We conclude that platelets, in response to an appropriate physiological surface, form typical actin bundles with vinculin at the termination of each bundle, in close relation to adhesion plaques. The signal for this translocation does not appear to depend on phosphorylation of vinculin or on phosphorylation or proteolysis of talin. Our findings support the conclusion that in platelets, as in nucleated cells, vinculin serves as at least part of the connection between bundled actin fibers and the extracellular matrix. Such a connection seems required for platelets' known ability to exert tension on surfaces.

show abstract

Section: Spreading and Activationmentioning

confidence: 75%

“…2a, arrow). This is where the platelet granules concentrate [Lewis et al, 1982;Loftus and Albrecht, 1984;Behnke and Bray, 19881. Antitropomyosin antibody showed periodicities along the linear fibers in some platelets (Fig.…”

Section: Stress Fiber Bundlesmentioning

confidence: 99%

Vinculin in relation to stress fibers in spread platelets

Nachmias

Golla

1991

Cell Motil. Cytoskeleton

View full text Add to dashboard Cite

show abstract

“…Only a very small part of the platelet cytoskeleton is visible in conventional TEM thin sections hindering an accurate determination of the overall three-dimensional organization and in situ relationships ofthe filamentous cytoskeletal elements. Wholemount preparations have therefore been increasingly utilized to study platelet ultrastructure (2,22,23,25,26,29,42). However, masking ofthe cytoskeletal elements by the extensive overlap ofother cytoplasmic constituents in intact wholemount preparations can interfere with the analysis of the interaction of the filamentous elements with each other or with other intracellular structures.…”

mentioning

confidence: 99%

“…While they are initially uniformly distributed, actin and myosin are segregated to selective areas as spreading progresses. Other studies employing transmission THE JOURNAL OF CELL BIOLOGY " VOLUME 98 JUNE 1984 2019-2025 ® The Rockefeller University Press -0021-9525/84/06/2019/07 $1 .00 electron microscopy (TEM)' have yielded considerable information regarding the types of filaments within platelets and overall platelet structure (22,23,42,(44)(45)(46)(47)(48) . Only a very small part of the platelet cytoskeleton is visible in conventional TEM thin sections hindering an accurate determination of the overall three-dimensional organization and in situ relationships ofthe filamentous cytoskeletal elements.…”

mentioning

confidence: 99%

Platelet activation and cytoskeletal reorganization: high voltage electron microscopic examination of intact and Triton-extracted whole mounts.

Loftus¹,

Choate²,

Albrecht³

1984

The Journal of Cell Biology

View full text Add to dashboard Cite

The sequential changes in the three-dimensional organization of the filamentous components of human platelets following surface activation were investigated in whole-mount preparations . Examination of intact and Triton-extracted platelets by high voltage electron microscopy provides morphological evidence of increased polymerization of actin into the filamentous form and an increased organization of the cytoskeletal elements after activation . The structure of resting platelets consists of the circumferential band of microtubules and a small number of microfilaments randomly arranged throughout a dense cytoplasmic matrix. Increased spreading is accompanied by cytoskeletal reorganization resulting in the development of distinct ultrastructural zones including the peripheral web, the outer filamentous zone, the "trabecular-like" inner filamentous zone, and the granulomere . These zones are present only in well-spread platelets during the late stages of surface activation and are retained following Triton extraction . Extraction of the less stable cytoplasmic components provides additional information about the underlying structure and filament interactions within each zone .The morphological transformation that accompanies platelet activation has been attributed to alterations involving both the distribution and the degree of polymerization of the various contractile and structural proteins within platelets. Contractile proteins have been implicated in many of the events ofactivation including centralization and secretion of granules, aggregation, and clot retraction (1,7,8,35,48). Recent biochemical studies of thrombin-induced platelet activation have demonstrated a time-dependent incorporation of actin into the filamentous form and an increase in the amount of myosin associated with the cytoskeleton (5, 20, 37). The organization of these platelet contractile proteins, particularly actin and myosin, has been studied at the light microscopic level through immunocytochemical techniques (9,11,12,33,35). These studies have indicated that there are temporal changes in the whole-cell distribution of actin and myosin within platelets. While they are initially uniformly distributed, actin and myosin are segregated to selective areas as spreading progresses. Other studies employing transmission THE JOURNAL OF CELL BIOLOGY " VOLUME 98 JUNE 1984 2019-2025 ® The Rockefeller University Press -0021-9525/84/06/2019/07 $1 .00 electron microscopy (TEM)' have yielded considerable information regarding the types of filaments within platelets and overall platelet structure (22,23,42,(44)(45)(46)(47)(48) . Only a very small part of the platelet cytoskeleton is visible in conventional TEM thin sections hindering an accurate determination of the overall three-dimensional organization and in situ relationships ofthe filamentous cytoskeletal elements. Wholemount preparations have therefore been increasingly utilized to study platelet ultrastructure (2,22,23,25,26,29,42). However, masking ofthe cytoskeletal elements by the exten...

show abstract

Three‐dimensional organization of the platelet cytoskeleton during adhesion in vitro: Observations on human and nonhuman primate cells

et al. 1983

Self Cite

View full text Add to dashboard Cite

Adhesion of platelets in vitro resulted in rapid polymerization of the amorphous cytoplasmic ground substance into an organized cytoskeletai superstructure. This cytoskeleton, characterized through the use of whole-mount and stereo (3-D), high-voltage microscopy in conjunction with morphometrics and cytochemistry, comprised four major size classes of filaments organized in distinctive zones. The central matrix, or granulomere, at the center of the cell mass, was an ill-defined meshwork of 80-100-A filaments which enshrouded granules, dense bodies, and elements of the dense tubular system as identified through peroxidase cytochemistry. Demarcating this central matrix was a trubeculur zune containing 30-50, 80-100, and 150-170A filaments in an open.and rigid-appearing lattice. Circumscribing the trabecular zone and extending to the margins of the hyalomere was the third region, the peripheral web, in which 70-A filaments were arranged in a tight honeycomb lattice. This organizational pattern was retained in cytoskeletons prepared by Triton x-100 extraction of the adherent cells, and was observed in basally located cells of aggregates which formed subsequent to adhesion. Our observations are consistent with biochemical studies of cytoskeletons prepared from suspended platelets and suggest a contractile protein composition for the superstructure during adhesion.

show abstract

Ultrastructural analysis of platelets in nonhuman primates

Cited by 18 publications

References 11 publications

Vinculin in relation to stress fibers in spread platelets

Vinculin in relation to stress fibers in spread platelets

Platelet activation and cytoskeletal reorganization: high voltage electron microscopic examination of intact and Triton-extracted whole mounts.

Three‐dimensional organization of the platelet cytoskeleton during adhesion in vitro: Observations on human and nonhuman primate cells

Contact Info

Product

Resources

About