scholarly journals Separation of important new platelet glycoproteins (GPIa, GPIc, GPIc*, GPIIa and GMP-140) by f.p.l.c. Characterization by monoclonal antibodies and gas-phase sequencing

1991 ◽  
Vol 279 (2) ◽  
pp. 419-425 ◽  
Author(s):  
B Catimel ◽  
S Parmentier ◽  
L L K Leung ◽  
J L McGregor
Keyword(s):  
Gas Phase ◽  
Polyclonal Antibodies ◽  
Umbilical Vein ◽  
Blood Platelets ◽  
Cdna Libraries ◽  
Membrane Glycoproteins ◽  
Terminal Sequence ◽  
Cdna Sequences ◽  
Functional Studies ◽  
Vinylidene Difluoride

A large number of membrane glycoproteins (around 40) are present on the surface of human blood platelets. Some of these glycoproteins are expressed in relatively small amounts, and their functions, as well as their structure, remain to be elucidated. The aim of the present study was to separate rapidly, under non-denaturing conditions, and characterize minor glycoproteins such as Very Late Antigens (VLA) (GPIa, GPIc, GPIc* and GPIIa) and GMP-140 (also known as PADGEM). VLAs and GMP-140 are respectively members of the integrin and selectin families. Platelet membrane glycoproteins were separated by wheat-germ agglutinin lectin affinity and Mono Q anion-exchange f.p.l.c. Peaks bearing isolated glycoproteins were electrophoresed on one- or two-dimensional SDS/polyacrylamide gels, Western blotted on to Immobilon poly(vinylidene difluoride) membranes and gas-phase-sequenced. The identity of isolated glycoproteins was also obtained by the use of monoclonal or polyclonal antibodies and tryptic peptide maps. Five minor [GPIa, GPIc, GPIc*, GPIIa and GMP 140 (PADGEM)], as well as a major (GPIIIb) glycoprotein, were eluted at low salt concentrations. GPIIb-IIIa and GPIb were eluted at high salt concentrations. The N-terminal sequence of platelet GPIa was identical with that obtained by Takada & Hemler [(1989) J. Cell Biol. 109, 397-407]. However, the N-terminal sequence of platelet GPIc + Ic* and GPIIa were found to differ from those deduced from cDNA sequences isolated from human placenta or umbilical-vein endothelial-cell cDNA libraries. The combined use of f.p.l.c. and gas-phase sequencing techniques provides a very powerful tool to separate and characterize rapidly platelet or other cellular proteins for structural, immunological and functional studies.

Platelet and Shear Rate Promote Tumor Cell Adhesion to Human Endothelial Extracellular Matrix - Absence of a Role for Platelet Cyclooxygenase

1989 ◽  
Vol 61 (03) ◽  
pp. 485-489 ◽  
Author(s):  
Eva Bastida ◽  
Lourdes Almirall ◽  
Antonio Ordinas
Keyword(s):  
Cell Adhesion ◽  
Shear Rate ◽  
Tumor Cell ◽  
Umbilical Vein ◽  
Blood Platelets ◽  
Flow Conditions ◽  
Tumor Cell Adhesion ◽  
Rate Dependent ◽  
Static Conditions

SummaryBlood platelets are thought to be involved in certain aspects of malignant dissemination. To study the role of platelets in tumor cell adherence to vascular endothelium we performed studies under static and flow conditions, measuring tumor cell adhesion in the absence or presence of platelets. We used highly metastatic human adenocarcinoma cells of the lung, cultured human umbilical vein endothelial cells (ECs) and extracellular matrices (ECM) prepared from confluent EC monolayers. Our results indicated that under static conditions platelets do not significantly increase tumor cell adhesion to either intact ECs or to exposed ECM. Conversely, the studies performed under flow conditions using the flat chamber perfusion system indicated that the presence of 2 × 105 pl/μl in the perfusate significantly increased the number of tumor cells adhered to ECM, and that this effect was shear rate dependent. The maximal values of tumor cell adhesion were obtained, in presence of platelets, at a shear rate of 1,300 sec-1. Furthermore, our results with ASA-treated platelets suggest that the role of platelets in enhancing tumor cell adhesion to ECM is independent of the activation of the platelet cyclooxygenase pathway.

scholarly journals Determination of platelet antigens and glycoproteins in the human fetus

Blood ◽  
1986 ◽  
Vol 68 (2) ◽  
pp. 488-492 ◽  
Author(s):  
Y Gruel ◽  
B Boizard ◽  
F Daffos ◽  
F Forestier ◽  
J Caen ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Human Fetus ◽  
Antenatal Diagnosis ◽  
Polyclonal Antibodies ◽  
Umbilical Vein ◽  
Membrane Surface ◽  
Platelet Suspension ◽  
Direct Puncture ◽  
Normal Human

Abstract The autosomal recessive transmission of Glanzmann's thrombasthenia (GT) and Bernard-Soulier syndrome (BSS), together with requests of families who already had children with these diseases, prompted us to investigate the feasibility of their antenatal diagnosis. The preliminary step leading to the early detection of GT or BSS was to characterize, in the normal human fetus, the platelet antigens and glycoproteins (GPs) and to define their normal amounts on the membrane surface. Blood samples from 32 fetuses between 18 to 26 weeks of gestation were collected by direct puncture of the umbilical vein using an ultrasound-guided needle. Polyclonal antibodies from human origin directed against PLA1, Leka antigens, and the GPIIb IIIa complex (IgGL), or murine monoclonal antibodies specific for GPIb (AN51, 6D1), GPIIIa (AP-3), or GPIIb IIIa (AP-2) were studied using platelet suspension immunofluorescence tests. The binding of each antibody was quantified using a cytofluorograph (Ortho 50H). PLA1 and Leka antigens were expressed in normal amounts on fetal platelets as early as 16 weeks of intrauterine life. The GPIIb IIIa complex quantified by polyclonal or monoclonal antibodies was in the same range in fetuses (IgGL = 427 +/- 23 AUF, AP-2 = 459.5 +/- 8.5; AP-3 = 536 +/- 14) and in adults (IgGL = 420 +/- 30; AP-2 = 498 +/- 11; AP-3 = 515 +/- 13). The platelet binding of antibodies that recognized GPIb was higher in fetuses (AN51 = 491.5 +/- 14; 6D1 = 479 +/- 15) than in adults (AN51 = 426.5 +/- 9; 6D1 = 449 +/- 8.7). These results suggest that immunological techniques can be applied as early as 18 weeks of gestation for the antenatal diagnosis of GT and BSS.

An electrogenic Na+- HCO 3 − cotransporter (NBC) with a novel COOH-terminus, cloned from rat brain

2000 ◽  
Vol 278 (6) ◽  
pp. C1200-C1211 ◽  
Author(s):  
Mark O. Bevensee ◽  
Bernhard M. Schmitt ◽  
Inyeong Choi ◽  
Michael F. Romero ◽  
Walter F. Boron
Keyword(s):  
Rat Brain ◽  
Cortical Neurons ◽  
Polyclonal Antibodies ◽  
Amino Acid Level ◽  
Cdna Libraries ◽  
Human Pancreas ◽  
Opposite Pattern ◽  
Reading Frame ◽  
Expression Studies ◽  
Rapid Amplification

We screened rat brain cDNA libraries and used 5′ rapid amplification of cDNA ends to clone two electrogenic Na+-[Formula: see text] cotransporter (NBC) isoforms from rat brain (rb1NBC and rb2NBC). At the amino acid level, one clone (rb1NBC) is 96% identical to human pancreas NBC. The other clone (rb2NBC) is identical to rb1NBC except for 61 unique COOH-terminal amino acids, the result of a 97-bp deletion near the 3′ end of the open-reading frame. Using RT-PCR, we confirmed that mRNA from rat brain contains this 97-bp deletion. Furthermore, we generated rabbit polyclonal antibodies that distinguish between the unique COOH-termini of rb1NBC (αrb1NBC) and rb2NBC (αrb2NBC). αrb1NBC labels an ∼130-kDa protein predominantly from kidney, and αrb2NBC labels an ∼130-kDa protein predominantly from brain. αrb2NBC labels a protein that is more highly expressed in cortical neurons than astrocytes cultured from rat brain; αrb1NBC exhibits the opposite pattern. In expression studies, applying 1.5% CO2/10 mM [Formula: see text] to Xenopus oocytes injected with rb2NBC cRNA causes 1) pHi to recover from the initial CO2-induced acidification and 2) the cell to hyperpolarize. Subsequently, removing external Na+ reverses the pHi increase and elicits a rapid depolarization. In the presence of 450 μM DIDS, removing external Na+ has no effect on pHi and elicits a small hyperpolarization. The rate of the pHidecrease elicited by removing Na+ is insensitive to removing external Cl−. Thus rb2NBC is a DIDS-sensitive, electrogenic NBC that is predominantly expressed in brain of at least rat.

scholarly journals Glycoprotein V is not the thrombin activation receptor on human blood platelets

Blood ◽  
1986 ◽  
Vol 68 (3) ◽  
pp. 720-725 ◽  
Author(s):  
D Bienz ◽  
W Schnippering ◽  
KJ Clemetson
Keyword(s):  
Platelet Activation ◽  
Polyclonal Antibodies ◽  
Blood Platelets ◽  
Polyacrylamide Gel Electrophoresis ◽  
Human Platelets ◽  
Exchange Chromatography ◽  
Thrombin Activation ◽  
Strong Candidate ◽  
Triton X ◽  
Kinetics Of

Thrombin activation of platelets involves two receptors: glycoprotein Ib (GPIb), which affects the kinetics of the response; and, as a strong candidate for the second, essential receptor, GPV, a hydrophobic, 82-kd glycoprotein with an isoelectric point (pI) of pH 5.85 to 6.55. Whole platelets were treated with endogenous platelets calcium-activated proteases, yielding a major fragment, GPV8, with molecular weight (mol wt) of 79 kilodaltons (kd). The fragment was purified by affinity chromatography on wheat germ agglutinin followed by ion exchange chromatography on DEAE-Sephacel using first a 0 to 0.7-mol/L and then a 0 to 0.3-mol/L NaCl gradient. A rabbit was immunized with the purified GPV8 for preparation of polyclonal antibodies. Crossed immunoelectrophoresis and two-dimensional polyacrylamide gel electrophoresis (PAGE) electrophoretic blotting with the separate phases of a Triton X-114 phase partition of human platelets showed the characteristic pattern of GPV in the hydrophobic phase. During thrombin- induced platelet aggregation GPV is hydrolysed, releasing a fragment, GPVf1, to the supernatant. The fragment GPVf1 still contains a thrombin- binding site. Anti-GPV antibodies blocked GPV proteolysis, but did not inhibit platelet activation induced by thrombin. We conclude that proteolysis of GPV by thrombin is not essential for platelet activation.

Abstract 181: BET Bromodomain Inhibition Suppresses Endothelial Inflammation and Atherosclerosis

2013 ◽  
Vol 33 (suppl_1) ◽  
Author(s):  
Jonathan Brown ◽  
Qiong Duan ◽  
Gabriel Griffin ◽  
Ronald Paranal ◽  
Steven Bair ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Rna Polymerase Ii ◽  
Umbilical Vein ◽  
Ldl Receptor ◽  
Flow Chamber ◽  
Cancer Therapies ◽  
Functional Studies ◽  
Endothelial Inflammation ◽  
Umbilical Vein Endothelial Cells

Introduction The BET bromodomain-containing family of proteins (BRD2, BRD3, BRD4) are epigenetic readers that coactivate transcription. Recent evidence indicates that BETs promote carcinogenesis and inflammation in sepsis, while BET bromodomain inhibitors are promising anti-cancer therapies. However, the role of chromatin remodeling in atherosclerosis in general and through BETs in particular remains unknown. Hypothesis We hypothesized that BET bromodomain-containing proteins coactivate proinflammatory responses in the vasculature with functional effects that promote atherogenesis. Methods and Results BET bromodomain inhibition, achieved with the highly selective, small-molecule inhibitor JQ1 significantly reduced early atherosclerosis (12 weeks) in cholesterol-fed, LDL receptor-null mice. In pursuing mechanisms for this effect, we identified BET protein expression in mouse and human endothelial cells (ECs) as well as endothelium from human atherosclerotic plaque. Treating human umbilical vein endothelial cells (HUVECs) with either JQ1 or siRNA to BRD2 or BRD4 potently suppresses TNFα-induced expression of adhesion molecules (SELE, VCAM1) and chemokines (CCL2, CXCL8). In chromatin immunoprecipation studies, TNFα stimulation of ECs recruited BETs to adhesion molecule and chemokine promoters coincident with RNA polymerase II and cyclin T1 localization, without altering NF-κB recruitment. In functional studies, JQ1 suppressed 1) monocyte adhesion to TNFα-activated HUVECs, 2) leukocyte rolling on cremaster post-capillary venules (intravital microscopy); 3) leukocyte transmigration (parallel-plate flow chamber); and 4) monocyte recruitment in thioglycolate-induced peritonitis in vivo . Conclusions BET bromodomain-containing proteins are novel determinants of pro-inflammatory transcription in the endothelium. Targeting chromatin by BET bromodomain inhibition may be a therapeutic strategy to limit atherosclerosis and other disorders involving endothelial inflammation.

scholarly journals Cloning of glycoprotein IIIa cDNA from human erythroleukemia cells and localization of the gene to chromosome 17

Blood ◽  
1988 ◽  
Vol 72 (2) ◽  
pp. 593-600 ◽  
Author(s):  
JP Rosa ◽  
PF Bray ◽  
O Gayet ◽  
GI Johnston ◽  
RG Cook ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Cdna Sequence ◽  
Chromosome 17 ◽  
Coding Region ◽  
Membrane Glycoproteins ◽  
Cdna Sequences ◽  
Hel Cells ◽  
Adhesive Proteins

Abstract Platelet aggregation requires the binding of adhesive proteins such as fibrinogen to the heterodimer of membrane glycoproteins IIb (GPIIb) and IIIa (GPIIIa). Human erythroleukemia (HEL) cells synthesize both GPIIb and GPIIIa. Using poly(A+) RNA purified from HEL cells, we constructed a cDNA library in the lambda gt10 phage vector. This library was screened with a 38mer oligonucleotide derived from a platelet GPIIIa peptide, and three overlapping cDNAs were isolated. The three inserts encompassed 3.5 kilobases (kb), including the entire coding region of mature GPIIIa (2,286 basepairs, bp) and 1.3 kb of 3′ untranslated sequence. All 222 residues determined directly from platelet GPIIIa tryptic peptides exactly matched the HEL cell-deduced amino acid sequence. The HEL cell sequence matched a previously reported endothelial cell cDNA sequence except for eight nucleotides. Five of these nucleotide differences were silent changes consistent with genetic polymorphisms. The other three differences resulted in changes in the deduced amino acid sequence of GPIIIa; reexamination of the endothelial cell cDNA sequence in these three areas revealed that it is actually identical to the HEL cell sequence. The virtual identity of the endothelial and HEL cell cDNA sequences provides direct evidence that GPIIIa is a subunit common to cell-adhesion receptors present in more than one cell type. We localized the gene for GPIIIa to chromosome 17, the same chromosome to which we had previously mapped the gene for GPIIb.

scholarly journals Isolation from human chronic-lymphocytic-leukaemia cells of membrane glycoproteins associated with Fc-receptor functions. Physical parameters and production of polyclonal antibodies

1987 ◽  
Vol 245 (1) ◽  
pp. 75-83 ◽  
Author(s):  
G Gorini ◽  
G A Medgyesi ◽  
M Garavini ◽  
K J Dorrington ◽  
J Down
Keyword(s):  
Chronic Lymphocytic Leukaemia ◽  
Gel Electrophoresis ◽  
Lymphocytic Leukaemia ◽  
Polyclonal Antibodies ◽  
Polyacrylamide Gel Electrophoresis ◽  
Fc Receptor ◽  
Polyacrylamide Gel ◽  
Two Dimensional ◽  
Membrane Glycoproteins

Two membrane glycoproteins that bound immune complexes and inhibited Fc-receptor- (FcR-)mediated functions in vitro were purified from human FcR+ chronic-lymphocytic-leukaemia cells. A multi-step purification was developed, consisting essentially in: (i) Tween 40 extraction of crude cell membranes; (ii) solubilization of membrane fragments by Renex-30; (iii) isolation of glycoproteins by affinity chromatography on Lens culinaris haemagglutinin-Sepharose; (iv) papain treatment of the eluted glycoproteins followed by gel-filtration chromatography; (v) purification by polyacrylamide-gel electrophoresis of two molecular species from the protein-size fraction enriched for immune-complex-binding activity. The two electrophoretically isolated components displayed apparent molecular masses of 70 and 45 kDa by SDS/polyacrylamide-gel electrophoresis and restricted charge heterogeneity by two-dimensional analysis. Two-dimensional peptide mapping revealed the presence of many peptides in common between the two proteins and the absence of a number of peptides in the 45 kDa component. These two polypeptides were used as immunogens to produce polyclonal antibodies that cross-reacted with both proteins and specifically inhibited FcR-mediated reactions in vitro. Furthermore, FcR-related components from detergent-extracted lysates of the human K562 and U937 cell lines or human placental membranes were revealed by the putative anti-FcR antibodies adsorbed on Protein A-Sepharose.

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