Platelets contain proteins immunologically related to red cell spectrin and protein 4.1

Davies, GE; Cohen, CM

doi:10.1182/blood.v65.1.52.bloodjournal65152

Cited by 7 publications

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“…It appears that the decrease of platelets is closely related to the reduction of erythrocytes in certain types of autoimmune diseases. Furthermore, these assumptions seem to be supported by recent findings: the presence of protein immunologically related red cell components in platelets (19), the presence of platelet glycoprotein IIb/IIIa complex on human hematopoietic stem cells (20), the derivation of platelet glycoproteins associated with blood monocytes from platelets (21), and the association of antibodies with ITP (22,23). It stands to reason that blood transfusion in aplastic anemia patients causes elevation of platelet antibodies (18,24).…”

Section: Discussionmentioning

confidence: 81%

Elevation of platelet‐associated IgG in aplastic anemia

Kawaguchi¹,

Haruna²,

Hikiji³

et al. 1992

Clinical Laboratory Analysis

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We determined platelet-associated IgG (PAIgG) levels in patients with aplastic anemia, idiopathic thrombocytopenic purpura (ITP), iron deficiency anemia, and systemic lupus erythematosus (SLE), as well as in normal healthy adults as a control group. To determine PAIgG levels, we used a competitive micro enzyme-linked immunosorbent assay, which had excellent reproducibility, recovery, and dilution. We confirmed its reliability by comparing it to the immunoradiometric assay. Both the aplastic anemia group (n = 27, mean +/- SD = 218.6 +/- 244.6 ng/10(7) platelets) and the ITP group (n = 82, mean +/- SD = 212.5 +/- 327.8 ng/10(7) platelets) had higher PAIgG levels than the SLE group (n = 4, mean +/- SD = 38.4 +/- 22.4 ng/10(7) platelets), iron deficiency anemia group (n = 10, mean +/- SD = 16.1 +/- 3.6 ng/10(7) platelets), and normal control group (n = 69, mean +/- SD = 16.1 +/- 3.6 ng/10(7) platelets. The higher platelet-associated IgG levels in aplastic anemia suggest that autoimmune mechanisms are involved.

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Section: Discussionmentioning

confidence: 81%

Elevation of platelet‐associated IgG in aplastic anemia

Kawaguchi¹,

Haruna²,

Hikiji³

et al. 1992

Clinical Laboratory Analysis

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“…Thus, the labeling of protein 4.1, protein 2.1, actin, and vimentin was not due to nonspecific adherence of antibodies to proteins. For a detailed characterization of each individual antibody, refer to Davies and Cohen (1985), Hynes and Destree (19781, and Byers and Fujiwara (1982). Immunoblots of erythrocyte ghosts, total BAEC lysate, PM-enriched fractions, and supernatants derived from PM aliquots exposed to l M KC1 are presented in Figure 4.…”

Section: -mentioning

confidence: 99%

Isolation of bovine aortic endothelial cell plasma membranes: Identification of membrane‐associated cytoskeletal proteins

Ketis

Hoover

Karnovsky

1986

Journal Cellular Physiology

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The plasma membrane of bovine aortic endothelium was isolated, characterized, and found to contain at least four membrane-associated cytoskeletal proteins. Exposure of the plasma membranes to salt media (up to 1M KCl) resulted in the release of 30% of the total plasma membrane-associated proteins and extraction with 1% Triton X-100, 60%. At least four heavily glycosylated bands (185-, 165-, 150-, and 130,000 mol-wt) were evident. The Triton-insoluble pellet fraction contained several major polypeptides (30-, 43-, 58-, and 240,000 mol-wt), two of which were identified by immunoblotting as cytoplasmic actin (43,000 mol-st) and vimentin (58,000 mol-wt). Strikingly, vimentin and a 240,000 mol-wt polypeptide were routinely present in approximately a mole ratio of 4:1 in more than 60% of the plasma membrane preparations. We also report the presence of a 2.1-like and a 4.1-like protein associated with plasma membranes. The 2.1-like protein demonstrated similar solubilities and apparent molecular weight (210,000) as erythroid protein 2.1. Likewise, the endothelial 4.1-like protein exhibited similar solubilities and apparent molecular weight as erythroid protein 4.1. Immunofluorescence staining of fixed and permeabilized cultures with anti-2.1 antibodies showed a fibrillar pattern. In contrast, cells stained with anti-protein 4.1 were brightly fluorescent, bearing both a diffuse and punctate pattern. This paper presents several novel observations pertaining to the composition of bovine aortic endothelial cell plasma membranes, namely: the presence of two erythroid-like cytoskeletal polypeptides; the presence of vimentin and a 240,000 mol-wt polypeptide in a 4:1 mole ratio in more than 60% of the plasma membrane preparations and the co-elution in a 4:1 mol ratio with a protein perturbant; and the inability to release actin from the plasma membrane preparations, suggesting the association of actin with other molecules in the plasma membrane preparation.

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“…Recent investigations have established that although about half of the actin in resting platelets is unpolymerized, stored as 1:1 complexes with/~4-thymosin (37,38) or profilin (28,29), the remainder of the actin in resting platelets is polymeric, consisting of filaments of ~1 #m in length. These filaments are crosslinked at high angles by actin-binding protein (ABP) 1 within the platelet substance and bind to a dense spectrin-rich shell that laminates the plasma membrane (4,(10)(11)(12). This article provides new details about the architecture of actin in the activated platelet and addresses the mechanism of how remodeling of the resting structure leads to the configuration characteristic of the activated cell.…”

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confidence: 99%

Mechanisms of actin rearrangements mediating platelet activation.

Hartwig

1992

The Journal of Cell Biology

380

297

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Abstract. The detergent-insoluble cytoskeleton of the resting human blood platelet contains ,x,2,000 actin filaments ~-,1/~m in length crosslinked at high angles by actin-binding protein and which bind to a spectrinrich submembrane lamina (Fox, J., J. Boyles, M. Berndt, P. Steffen, and L. Anderson. 1988. J. Cell Biol. 106:1525-1538 Hartwig, J., and M. DeSisto. 1991. J. Cell Biol. 112:407-425). Activation of the platelets by contact with glass results within 30 s in a doubling of the polymerized actin content of the cytoskeleton and the appearance of two distinct new actin structures: bundles of long filaments within filopodia that end at the filopodial tips (filopodial bundies) and a circumferential zone of orthogonally arrayed short filaments within lamellipodia (lamellipodial network). Neither of these structures appears in cells exposed to glass with cytochalasin B present; instead the cytoskeletons have numerous 0.1-0. 3-~m-long actin filament fragments attached to the membrane lamina. With the same time course as the glassinduced morphological changes, cytochalasin-sensitive actin nucleating activity, initially low in cytoskeletons of resting platelets, increases 10-fold in cytoskeletons of thrombin-activatexl platelets. This activity decays with a time course consistent with depolymerization of 0.1-0.3-/zm-long actin filaments, and phailoidin inhibits this decay. Cytochalasin-insensitive and calciumdependent nucleation activity also increases markedly in platelet extracts after thrombin activation of the cells. Prevention of the rise in cytosolic Ca 2+ normally associated with platelet activation with the permeant Ca ~+ chelator, Quin-2, inhibits formation of lamellipodial networks but not filopodial bundles after glass contact and reduces the cytochalasin B-sensitive nucleation activity by 60% after thrombin treatment. The filopodial bundles, however, are abnormal in that they do not end at the filopodial tips but form loops and return to the cell body. Addition of calcium to chelated cells restores lamellipodial networks, and calcium plus A23187 results in cytoskeletons with highly fragmented actin filaments within seconds. Immunogold labeling with antibodies against gelsolin reveals gelsolin molecules at the ends of filaments attached to the submembrane lamina of resting cytoskeletons and at the ends of some filaments in the lamellipodial networks and filopodial bundles of activated cytoskeletons. Addition of monomeric actin to myosin subfragment l-labeled activated cytoskeletons leads to new (undecorated) filament growth off the ends of filaments in the filopodial bundles and the lamellipodial network. The simplest explanation for these findings is that gelsolin caps the barbed ends of the filaments in the resting platelet. Uncapping some of these filaments after activation leads to filopodial bundles. The calcium transient associated with platelet activation induces fragmentation of peripheral actin filaments by free gelsolin, and the resulting actin fragments, after dissociation of gelsolin from th...

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Platelets contain proteins immunologically related to red cell spectrin and protein 4.1

Cited by 7 publications

References 0 publications

Elevation of platelet‐associated IgG in aplastic anemia

Elevation of platelet‐associated IgG in aplastic anemia

Isolation of bovine aortic endothelial cell plasma membranes: Identification of membrane‐associated cytoskeletal proteins

Mechanisms of actin rearrangements mediating platelet activation.

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