scholarly journals Neuronal filopodium formation induced by the membrane glycoprotein M6a (Gpm6a) is facilitated by coronin-1a, Rac1, and p21-activated kinase 1 (Pak1)

2016 ◽  
Vol 137 (1) ◽  
pp. 46-61 ◽  
Author(s):  
Anabel Alvarez Juliá ◽  
Alberto C. Frasch ◽  
Beata Fuchsova
Keyword(s):  
Membrane Glycoprotein ◽  
P21 Activated Kinase ◽  
Filopodium Formation

scholarly journals Characterization of Pseudomonas aeruginosa Exoenzyme S as a Bifunctional Enzyme in J774A.1 Macrophages

2003 ◽  
Vol 71 (9) ◽  
pp. 5296-5305 ◽  
Author(s):  
Claudia L. Rocha ◽  
Jenifer Coburn ◽  
Elizabeth A. Rucks ◽  
Joan C. Olson
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Rho Proteins ◽  
Exoenzyme S ◽  
Rho Family ◽  
P21 Activated Kinase ◽  
Adp Ribosyltransferase ◽  
Filopodium Formation ◽  
Membrane Ruffle

ABSTRACT Pseudomonas aeruginosa exoenzyme S (ExoS) is a type III secretion (TTS) effector, which includes both a GTPase-activating protein (GAP) activity toward the Rho family of low-molecular-weight G (LMWG) proteins and an ADP-ribosyltransferase (ADPRT) activity that targets LMWG proteins in the Ras, Rab, and Rho families. The coordinate function of both activities of ExoS in J774A.1 macrophages was assessed by using P. aeruginosa strains expressing and translocating wild-type ExoS or ExoS defective in GAP and/or ADPRT activity. Distinct and coordinated functions were identified for both domains. The GAP activity was required for the antiphagocytic effect of ExoS and was linked to interference of lamellopodium and membrane ruffle formation. Alternatively, the ADPRT activity of ExoS altered cellular adherence and morphology and was linked to effects on filopodium formation. The cellular mechanism of ExoS GAP activity included an inactivation of Rac1 function, as determined in p21-activated kinase 1-glutathione S-transferase (GST) pull-down assays. The ADPRT activity of ExoS targeted Ras and RalA but not Rab or Rho proteins, and Ral binding protein 1-GST pull-down assays identified an effect of ExoS ADPRT activity on RalA activation. The results from these studies confirm the bifunctional nature of ExoS activity within macrophages when translocated by TTS.

Glycoprotein Ib Has a Partial Role in Platelet-von Willebrand Factor Collagen Interaction

1988 ◽  
Vol 60 (02) ◽  
pp. 182-187 ◽  
Author(s):  
Morio Aihara ◽  
Ken Tamura ◽  
Ryuko Kawarada ◽  
Keizou Okawa ◽  
Yutaka Yoshida
Keyword(s):  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Ricinus Communis ◽  
Protein S ◽  
Platelet Membrane ◽  
Membrane Glycoprotein ◽  
Normal Plasma ◽  
Ricinus Communis Agglutinin ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryThe adhesion of human fixed washed platelets (FWP) to collagen was decreased after treatment with Serratia marcescens protease (SP), which removed 95% of the glycocalicin from platelet membrane glycoprotein (GP) lb. However, the diminished adhesion of SP treated FWP to collagen could still be increased in the presence of purified von Willebrand factor (vWF). This ability of vWF to increase FWP adhesion to collagen is defined as collagen cofactor (CCo). The adhesion of FWP to collagen was not affected by a monoclonal antibody (MAb) to GP Ilb/IIIa (10E5), that inhibits ADP and collagen induced platelet aggregation. On the other hand, it was decreased by 50% by a MAb to GP lb (6D1), that inhibits ristocetin induced platelet aggregation. Adhesion of FWP in buffer to collagen was completely inhibited by Ricinus communis agglutinin I or concanavalin A, while Lens culinalis agglutinin and wheat germ agglutinin showed 50% inhibition. The FWP adhesion to collagen in the presence of vWF (normal plasma) was unaffected by MAbs to GP Ilb/IIIa (10E5, P2, HPL1) but was decreased to 32-38% by MAbs to GP lb (6D1, AN51, HPL11). A MAb to vWF (CLB-RAg 35), that inhibits ristocetin induced binding of vWF to platelets, decreased the CCo of normal plasma by 70%. The MAb, CLB-RAg 201, that inhibits the binding of vWF to collagen, completely inhibited the CCo of normal plasma. In conclusion, our data suggest that (1) GP lb has a partial role in FWP adhesion to collagen; (2) the binding of vWF to collagen is required for the expression of CCo; (3) CCo is partly mediated through GP lb; but (4) other platelet membrane protein(s) besides GP lb or GP Ilb/IIIa must also be involved in FWP-vWF-collagen interactions.

Ristocetin and Botrocetin Involve Two Distinct Domains of von Willebrand Factor for Binding to Platelet Membrane Glycoprotein lb

1990 ◽  
Vol 64 (02) ◽  
pp. 326-332 ◽  
Author(s):  
J P Girma ◽  
Y Takahashi ◽  
A Yoshioka ◽  
J Diaz ◽  
D Meyer
Keyword(s):  
Von Willebrand Factor ◽  
Synthetic Peptides ◽  
Competitive Inhibition ◽  
Final Concentration ◽  
Binding Domain ◽  
Platelet Membrane ◽  
Platelet Glycoprotein ◽  
Membrane Glycoprotein ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryWe have evidence that ristocetin and botrocetin mediate binding of von Willebrand Factor (vWF) to platelet glycoprotein lb (GPIb) through two distinct domains on the vWF molecule. This was established by using monoclonal antibodies (MAbs) to vWF and synthetic peptides derived from the sequence of vWF. MAb 322 and MAb NMC/vW 4 both recognize native vWF as well as fragments containing the GPIb-binding domain of vWF, obtained with the following enzymes: trypsin (116 kDa), V-8 pro tease (Spill, 320 kDa) and V-8 protease plus subtilisin (33-28 kDa). Nevertheless, the lack of reciprocal displacement between the two MAbs in experiments of competitive inhibition for binding to vWF demonstrate that their respective epitopes are separate. Both MAbs inhibit 125I-vWF binding to platelet membrane GPIb and vWF-dependent platelet agglutination induced by ristocetin. However, only MAb NMC/vW4 inhibits these functions in the presence of botrocetin and when ristocetin-induced platelet agglutination is inhibited by MAb 322, botrocetin is still able to restore the agglutination. The involvement of two distinct domains of vWF for binding to GPIb in the presence of ristocetin or botrocetin was confirmed in experiments of binding of 125I-vWF to platelets using as competitor synthetic peptides corresponding to the GPIb binding domain of vWF (Cys 474 to Pro 488 and Ser 692 to Pro 708). At a final concentration of 2.5 mM both peptides inhibit more than 90% of the binding of vWF to ristocetin-treated platelets but are unable to modify this binding in the presence of botrocetin. In conclusion our data suggest that botrocetin and ristocetin involve distinct sites on vWF for binding to GPIb.

Responses of Platelets to Strains of Streptococcus sanguis: Findings in Healthy Subjects, Bernard-Soulier, Glanzmann’s, and Collagen-Unresponsive Patients

1987 ◽  
Vol 57 (02) ◽  
pp. 222-225 ◽  
Author(s):  
A H Soberay ◽  
M C Herzberg ◽  
J D Rudney ◽  
H K Nieuwenhuis ◽  
J J Sixma ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Healthy Subjects ◽  
Normal Subjects ◽  
Membrane Glycoprotein ◽  
Response Mechanism ◽  
Platelet Response ◽  
Induce Platelet Aggregation ◽  
Streptococcus Sanguis ◽  
Lag Times ◽  
Bernard Soulier Syndrome

SummaryThe ability of endocarditis and dental strains of Streptococcus sanguis to induce platelet aggregation in plasma (PRP) from normal subjects were examined and compared to responses of PRP with known platelet membrane glycoprotein (GP) and response defects. S. sanguis strains differed in their ability to induce normal PRPs to aggregate. Strains that induced PRP aggregation in more than 60% of donors were significantly faster agonists (mean lag times to onset of aggregation less than 6 min) than those strains inducing response in PRPs of fewer than 60% of donors.Platelets from patients with Bernard-Soulier syndrome aggregated in response to strains of S. sanguis. In contrast, platelets from patients with Glanzmann’s thrombasthenia and from a patient with a specific defect in response to collagen were unresponsive to S. sanguis. These observations show that GPIb and V are not essential, but GPIIb-IIIa and GPIa are important in the platelet response mechanism to S. sanguis. Indeed, the data suggests that the platelet interaction mechanisms of S. sanguis and collagen may be similar.

Acquired Disorder of Platelet Function Associated with Autoantibodies against Membrane Glycoprotein IIb-IIIa Complex - 1. Glycoprotein Analysis

1991 ◽  
Vol 65 (05) ◽  
pp. 491-496 ◽  
Author(s):  
M Meyer ◽  
C M Kirchmaier ◽  
A Schirmer ◽  
P Spangenberg ◽  
Ch Ströhl ◽  
...  
Keyword(s):  
Platelet Count ◽  
Platelet Aggregation ◽  
Platelet Adhesion ◽  
Bleeding Time ◽  
Membrane Glycoprotein ◽  
Membrane Glycoproteins ◽  
Abnormal Behaviour ◽  
Thrombocytopenic Purpura ◽  
Immunoelectrophoretic Analysis ◽  
Prolonged Bleeding Time

SummaryA patient with idiopathic thrombocytopenic purpura developed after splenectomy a thrombasthenia-like severe haemor-rhagic diathesis characterized by a normal or subnormal platelet count, prolonged bleeding time, strongly reduced platelet adhesion to glass and defective platelet aggregation in response to ADP and collagen. In contrast to hereditary thrombasthenia membrane glycoproteins (GP) lib and Ilia were normally present in the patient’s platelets. Immunoelectrophoretic analysis revealed an abnormal behaviour of the patient’s GP IIb-IIIa complex. Autoantibodies against GP IIb-IIIa were detected in Triton-extracted washed platelets. Incubation of normal platelets with plasma from the patient resulted in a similar immunoelectrophoretic abnormality of the GP IIb-IIIa complex indicating that bound autoantibodies (IgG) are responsible for the abnormal immunoelectrophoretic behaviour of the patient’s GP IIb-IIIa complex. Platelet fibrinogen was severely reduced similar to classical thrombasthenia suggesting that the GP IIb-IIIa complex is involved in platelet fibrinogen storage.

Differential Ability of Agonists to Express Distinct Pools of Fibrinogen (Gpllb/llla) Receptors which Can Mediate the Aggregation of Human Platelets

1989 ◽  
Vol 62 (03) ◽  
pp. 955-961 ◽  
Author(s):  
Ian S Watts ◽  
Rebecca J Keery ◽  
Philip Lumley
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Surface Membrane ◽  
Blood Platelet ◽  
Human Platelets ◽  
Membrane Glycoprotein ◽  
Platelet Surface ◽  
Human Platelet Aggregation ◽  
Differential Ability ◽  
Blood Platelet Aggregation

SummaryWe have investigated the effect of two procedures that modify human platelet surface membrane glycoprotein (Gp) IIb and IIIa complexes upon whole blood platelet aggregation to a range of agonists. (A) Irreversible disruption of complexes by temporary (30 min) Ca2+-deprivation with EGTA at 37° C. (B) Binding of a monoclonal antibody M148 to the complex. EGTA exposure abolished aggregation to ADP, adrenaline and PAF. In contrast, full aggregation curves to collagen and U-46619 could still be established. EGTA exposure reduced M148 binding to platelets by 80%. Excess M148 abolished aggregation to ADP, PAF, collagen and U-46619. However, upon removal of unbound antibody from platelets full aggregation curves to collagen and U-46619 but not to ADP and PAF could be re-established. Thus human platelet aggregation to ADP, PAF and adrenaline appears absolutely dependent upon surface membrane GpIIb/IIIa complexes. In contrast, collagen and U-46619 cause expression of an additional distinct pool of Gp complexes inaccessible to EGTA and M148 in unstimulated platelets which is intimately involved in aggregation to these agonists.

Molecular Basis and Clinical Aspects of Hereditary Megakaryocyte and Platelet Membrane Glycoprotein Disorders

1996 ◽  
Vol 16 (02) ◽  
pp. 114-138 ◽  
Author(s):  
R. E. Scharf
Keyword(s):  
Genetic Basis ◽  
Molecular Mechanisms ◽  
Molecular Genetic ◽  
Platelet Membrane ◽  
Clinical Aspects ◽  
Membrane Glycoprotein ◽  
Membrane Glycoproteins ◽  
Membrane Expression ◽  
Receptor Complexes ◽  
Platelet Membrane Glycoprotein

SummarySpecific membrane glycoproteins (GP) expressed by the megakaryocyte-platelet system, including GPIa-lla, GPIb-V-IX, GPIIb-llla, and GPIV are involved in mediat-ing platelet adhesion to the subendothelial matrix. Among these glycoproteins, GPIIb-llla plays a pivotal role since platelet aggregation is exclusively mediated by this receptor and its interaction with soluble macromolecular proteins. Inherited defects of the GPIIb-llla or GPIb-V-IX receptor complexes are associated with bleeding disorders, known as Glanzmann's thrombasthenia, Bernard-Soulier syndrome, or platelet-type von Willebrand's disease, respectively. Using immuno-chemical and molecular biology techniques, rapid advances in our understanding of the molecular genetic basis of these disorders have been made during the last few years. Moreover, analyses of patients with congenital platelet membrane glycoprotein abnormalities have provided valuable insights into molecular mechanisms that are required for structural and functional integrity, normal biosynthesis of the glycoprotein complexes and coordinated membrane expression of their constituents. The present article reviews the current state of knowledge of the major membrane glycoproteins in health and disease. The spectrum of clinical bleeding manifestations and established diagnostic criteria for each of these dis-orders are summarized. In particular, the variety of molecular defects that have been identified so far and their genetic basis will be discussed.

Human Blood Platelet Membrane Glycoproteins

1979 ◽  
Vol 42 (05) ◽  
pp. 1490-1502 ◽  
Author(s):  
C S P Jenkins ◽  
E F Ali-Briggs ◽  
G T E Zonneveld ◽  
A Sturk ◽  
J Clemetson
Keyword(s):  
Specific Problem ◽  
Sodium Dodecyl ◽  
Normal Subjects ◽  
Blood Platelet ◽  
Platelet Membrane ◽  
Buffer System ◽  
Membrane Glycoprotein ◽  
Membrane Glycoproteins ◽  
Human Blood Platelet ◽  
Electrophoretic Techniques

SummaryThe separation of the major platelet membrane glycoproteins of normal subjects and subjects with well defined platelet membrane glycoprotein abnormalities have been examined using four different polyacrylamide gel electrophoretic techniques (continuous and discontinuous). The mobilities of the resolved glycoprotein bands have been correlated with the glycoprotein nomenclature proposed for the conventional sodium dodecyl sulphate- phosphate buffer system. Since the glycoprotein distribution varies depending on the system used, the merits of each method should be considered before application to a specific problem.

Sign in / Sign up

Export Citation Format

Share Document