scholarly journals The role of sialic acid in the activation of platelets by wheat germ agglutinin

Blood ◽  
1984 ◽  
Vol 63 (1) ◽  
pp. 181-187 ◽  
Author(s):  
P Ganguly ◽  
NG Fossett
Keyword(s):  
Sialic Acid ◽  
Dissociation Constant ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Blood Platelets ◽  
Critical Role ◽  
Human Platelets ◽  
Apparent Dissociation Constant ◽  
Serotonin Secretion

Abstract Sialic acid is believed to play a critical role in the survival of blood platelets in circulation. Wheat germ agglutinin, which shows specificity for sialic acid, N-acetylglucosamine, and N- acetylgalactosamine, strongly activates platelets. The role of sialic acid in platelet activation by this lectin was studied utilizing neuraminidase-treated platelets and the succinylated lectin that has been reported not to recognize sialic acid. The succinylated lectin had a dimeric structure similar to the native lectin, but migrated more slowly in gel electrophoresis. The modified lectin bound to about 2.8 X 10(5) sites/cell, with an apparent dissociation constant of 2 microM compared to 5 X 10(5) sites/cell and a dissociation constant of 0.4 microM for the native lectin. The succinylated lectin neither aggregated nor agglutinated platelets, but agglutination of red cells in microtiter plates was normal. Aggregation of platelets by either wheat germ agglutinin or ristocetin was not affected by the succinylated lectin. Since the native wheat germ agglutinin is a strong activator of platelets and the succinylated derivative was devoid of all activity, it appears that a sialoprotein acts as the biologic receptor of wheat germ agglutinin in human platelets. This suggestion was strengthened by the observation that platelets treated with different concentrations of neuraminidase had a decreased capacity to bind this lectin. These platelets also showed reduced aggregation and serotonin secretion when activated with the native lectin. Since sialic acid has been implicated in the removal of platelets from circulation, wheat germ agglutinin may prove to be a useful tool to explore those clinical conditions in which platelet survival is shortened.

scholarly journals The role of sialic acid in the activation of platelets by wheat germ agglutinin

Blood ◽  
1984 ◽  
Vol 63 (1) ◽  
pp. 181-187
Author(s):  
P Ganguly ◽  
NG Fossett
Keyword(s):  
Sialic Acid ◽  
Dissociation Constant ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Blood Platelets ◽  
Critical Role ◽  
Human Platelets ◽  
Apparent Dissociation Constant ◽  
Serotonin Secretion

Sialic acid is believed to play a critical role in the survival of blood platelets in circulation. Wheat germ agglutinin, which shows specificity for sialic acid, N-acetylglucosamine, and N- acetylgalactosamine, strongly activates platelets. The role of sialic acid in platelet activation by this lectin was studied utilizing neuraminidase-treated platelets and the succinylated lectin that has been reported not to recognize sialic acid. The succinylated lectin had a dimeric structure similar to the native lectin, but migrated more slowly in gel electrophoresis. The modified lectin bound to about 2.8 X 10(5) sites/cell, with an apparent dissociation constant of 2 microM compared to 5 X 10(5) sites/cell and a dissociation constant of 0.4 microM for the native lectin. The succinylated lectin neither aggregated nor agglutinated platelets, but agglutination of red cells in microtiter plates was normal. Aggregation of platelets by either wheat germ agglutinin or ristocetin was not affected by the succinylated lectin. Since the native wheat germ agglutinin is a strong activator of platelets and the succinylated derivative was devoid of all activity, it appears that a sialoprotein acts as the biologic receptor of wheat germ agglutinin in human platelets. This suggestion was strengthened by the observation that platelets treated with different concentrations of neuraminidase had a decreased capacity to bind this lectin. These platelets also showed reduced aggregation and serotonin secretion when activated with the native lectin. Since sialic acid has been implicated in the removal of platelets from circulation, wheat germ agglutinin may prove to be a useful tool to explore those clinical conditions in which platelet survival is shortened.

scholarly journals The investigation of the changes in the surface glycoconjugates using two different spheroid models of breast cancer cells and availability assessment of these spheroid models for rapid diagnosis

2021 ◽  
Vol 38 (3) ◽  
pp. 266-271
Author(s):  
Yosun MATER ◽  
Günnur DEMİRCAN
Keyword(s):  
Breast Cancer ◽  
Cell Culture ◽  
Sialic Acid ◽  
Cancer Cell ◽  
Breast Cancer Cell ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Sialic Acids ◽  
Maackia Amurensis ◽  
Maackia Amurensis Lectin

The importance of early cancer diagnosis has led to development of many different diagnostic methods. In this context, the studies investigating the presence and amount of sugar residues to use as indicators in the identification of cancer cell type have become prominent. In the present study, sialic acids found on the membrane surfaces of ER (+) MCF-7 and ER (-) MDA-MB-231 breast cancer cell lines were labeled using three-dimensional (3D) cell culture (Spheroid) model as the closest method to the patient sample, thus its natural environment, among the cell culture methods. These sugar units that play a role in regulation of important immune characteristics such as recognition, binding and metastasis were made visualizable by applying fluorescent-labeled lectins such as FITC-(Wheat Germ Agglutinin) specifically binding to sialic acid units (GlcNAc, Neu5Ac) including particularly ß-GlcNAc and FITC-(Maackia Amurensis-Lectin-1) specifically binding to Galß4GlcNAc type sialic acids. These glycan units were specifically labeled with FITC-(Maackia Amurensis-Lectin-1) and FITC- (Wheat Germ Agglutinin) and radiation intensities were analyzed relatively. The two different breast cancer cell cultures were compared with respect to change in the amounts of sialic acid residues containing α-2,3- and α-2,6 bonds using fluorescent-labeled lectins. In the present study, we have performed a precise, accurate and rapid determination of the sugar content in the different breast cancer cell surface lines by means of fluorescent-labeled lectins and carried out a relative comparison between the micrographs.

Role of phosphoinositide 3-kinase β in platelet aggregation and thromboxane A2 generation mediated by Gi signalling pathways

2010 ◽  
Vol 429 (2) ◽  
pp. 369-377 ◽  
Author(s):  
Analia Garcia ◽  
Soochong Kim ◽  
Kamala Bhavaraju ◽  
Simone M. Schoenwaelder ◽  
Satya P. Kunapuli
Keyword(s):  
Platelet Aggregation ◽  
Critical Role ◽  
Thromboxane A2 ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
P2y12 Receptor ◽  
Functional Responses ◽  
Induce Platelet Aggregation ◽  
Erk Phosphorylation

PI3Ks (phosphoinositide 3-kinases) play a critical role in platelet functional responses. PI3Ks are activated upon P2Y12 receptor stimulation and generate pro-aggregatory signals. P2Y12 receptor has been shown to play a key role in the platelet aggregation and thromboxane A2 generation caused by co-stimulation with Gq or Gz, or super-stimulation of Gi pathways. In the present study, we evaluated the role of specific PI3K isoforms α, β, γ and δ in platelet aggregation, thromboxane A2 generation and ERK (extracellular-signal-regulated kinase) activation. Our results show that loss of the PI3K signal impaired the ability of ADP to induce platelet aggregation, ERK phosphorylation and thromboxane A2 generation. We also show that Gq plus Gi- or Gi plus Gz-mediated platelet aggregation, ERK phosphorylation and thromboxane A2 generation in human platelets was inhibited by TGX-221, a PI3Kβ-selective inhibitor, but not by PIK75 (a PI3Kα inhibitor), AS252424 (a PI3Kγ inhibitor) or IC87114 (a PI3Kδ inhibitor). TGX-221 also showed a similar inhibitory effect on the Gi plus Gz-mediated platelet responses in platelets from P2Y1−/− mice. Finally, 2MeSADP (2-methyl-thio-ADP)-induced Akt phosphorylation was significantly inhibited in the presence of TGX-221, suggesting a critical role for PI3Kβ in Gi-mediated signalling. Taken together, our results demonstrate that PI3Kβ plays an important role in ADP-induced platelet aggregation. Moreover, PI3Kβ mediates ADP-induced thromboxane A2 generation by regulating ERK phosphorylation.

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