Publications by authors named "Christel Poujol"

17 Publications

  • Page 1 of 1

Engineering selective competitors for the discrimination of highly conserved protein-protein interaction modules.

Nat Commun 2019 10 4;10(1):4521. Epub 2019 Oct 4.

Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, F-33076, Bordeaux, France.

Designing highly specific modulators of protein-protein interactions (PPIs) is especially challenging in the context of multiple paralogs and conserved interaction surfaces. In this case, direct generation of selective and competitive inhibitors is hindered by high similarity within the evolutionary-related protein interfaces. We report here a strategy that uses a semi-rational approach to separate the modulator design into two functional parts. We first achieve specificity toward a region outside of the interface by using phage display selection coupled with molecular and cellular validation. Highly selective competition is then generated by appending the more degenerate interaction peptide to contact the target interface. We apply this approach to specifically bind a single PDZ domain within the postsynaptic protein PSD-95 over highly similar PDZ domains in PSD-93, SAP-97 and SAP-102. Our work provides a paralog-selective and domain specific inhibitor of PSD-95, and describes a method to efficiently target other conserved PPI modules.
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http://dx.doi.org/10.1038/s41467-019-12528-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6778148PMC
October 2019

Self-propelling vesicles define glycolysis as the minimal energy machinery for neuronal transport.

Nat Commun 2016 10 24;7:13233. Epub 2016 Oct 24.

Institut Curie, F-91405 Orsay, France.

The glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) facilitates fast axonal transport in neurons. However, given that GAPDH does not produce ATP, it is unclear whether glycolysis per se is sufficient to propel vesicles. Although many proteins regulating transport have been identified, the molecular composition of transported vesicles in neurons has yet to be fully elucidated. Here we selectively enrich motile vesicles and perform quantitative proteomic analysis. In addition to the expected molecular motors and vesicular proteins, we find an enrichment of all the glycolytic enzymes. Using biochemical approaches and super-resolution microscopy, we observe that most glycolytic enzymes are selectively associated with vesicles and facilitate transport of vesicles in neurons. Finally, we provide evidence that mouse brain vesicles produce ATP from ADP and glucose, and display movement in a reconstituted in vitro transport assay of native vesicles. We conclude that transport of vesicles along microtubules can be autonomous.
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http://dx.doi.org/10.1038/ncomms13233DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5078996PMC
October 2016

Meeting report--Imaging the Cell.

J Cell Sci 2015 Nov;128(21):3843-7

INSERM, U1053, Bordeaux F-33076, France Université de Bordeaux, Bordeaux F-33076, France

Every two years, the French Society for Cell Biology (SBCF) organises an international meeting called 'Imaging the Cell'. This year, the 8th edition was held on 24-26 June 2015 at University of Bordeaux Campus Victoire in the city of Bordeaux, France, a UNESCO World Heritage site. Over the course of three days, the meeting provided a forum for experts in different areas of cell imaging. Its unique approach was to combine conventional oral presentations during morning sessions with practical workshops at hosting institutes and the Bordeaux Imaging Center during the afternoons. The meeting, co-organised by Violaine Moreau and Frédéric Saltel (both INSERM U1053, Bordeaux, France), Christel Poujol and Fabrice Cordelières (both Bordeaux Imaging Center, Bordeaux, France) and Isabelle Sagot (Institut de Biochimie et Génétique Cellulaires, Bordeaux, France), brought together about 120 scientists including 16 outstanding speakers to discuss the latest advances in cell imaging. Thanks to recent progress in imaging technologies, cell biologists are now able to visualise, follow and manipulate cellular processes with unprecedented accuracy. The meeting sessions and workshops highlighted some of the most exciting developments in the field, with sessions dedicated to optogenetics, high-content screening, in vivo and live-cell imaging, correlative light and electron microscopy, as well as super-resolution imaging.
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http://dx.doi.org/10.1242/jcs.180042DOI Listing
November 2015

Lengthening of the Stargazin Cytoplasmic Tail Increases Synaptic Transmission by Promoting Interaction to Deeper Domains of PSD-95.

Neuron 2015 Apr 2;86(2):475-89. Epub 2015 Apr 2.

University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; Bordeaux Imaging Center, UMS 3420 CNRS, US4 INSERM, University of Bordeaux, 33000 Bordeaux, France. Electronic address:

PSD-95 is a prominent organizer of the postsynaptic density (PSD) that can present a filamentous orientation perpendicular to the plasma membrane. Interactions between PSD-95 and transmembrane proteins might be particularly sensitive to this orientation, as "long" cytoplasmic tails might be required to reach deeper PSD-95 domains. Extension/retraction of transmembrane protein C-tails offer a new way of regulating binding to PSD-95. Using stargazin as a model, we found that enhancing the apparent length of stargazin C-tail through phosphorylation or by an artificial linker was sufficient to potentiate binding to PSD-95, AMPAR anchoring, and synaptic transmission. A linear extension of stargazin C-tail facilitates binding to PSD-95 by preferentially engaging interaction with the farthest located PDZ domains regarding to the plasma membrane, which present a greater affinity for the stargazin PDZ-domain-binding motif. Our study reveals that the concerted orientation of the stargazin C-tail and PSD-95 is a major determinant of synaptic strength.
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http://dx.doi.org/10.1016/j.neuron.2015.03.013DOI Listing
April 2015

CYFIP1 coordinates mRNA translation and cytoskeleton remodeling to ensure proper dendritic spine formation.

Neuron 2013 Sep;79(6):1169-82

VIB Center for Biology of Disease, KULeuven, 3000 Leuven, Belgium; Center for Human Genetics and Leuven Institute for Neuroscience and Disease (LIND), KULeuven, 3000 Leuven, Belgium.

The CYFIP1/SRA1 gene is located in a chromosomal region linked to various neurological disorders, including intellectual disability, autism, and schizophrenia. CYFIP1 plays a dual role in two apparently unrelated processes, inhibiting local protein synthesis and favoring actin remodeling. Here, we show that brain-derived neurotrophic factor (BDNF)-driven synaptic signaling releases CYFIP1 from the translational inhibitory complex, triggering translation of target mRNAs and shifting CYFIP1 into the WAVE regulatory complex. Active Rac1 alters the CYFIP1 conformation, as demonstrated by intramolecular FRET, and is key in changing the equilibrium of the two complexes. CYFIP1 thus orchestrates the two molecular cascades, protein translation and actin polymerization, each of which is necessary for correct spine morphology in neurons. The CYFIP1 interactome reveals many interactors associated with brain disorders, opening new perspectives to define regulatory pathways shared by neurological disabilities characterized by spine dysmorphogenesis.
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http://dx.doi.org/10.1016/j.neuron.2013.06.039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3781321PMC
September 2013

Quantitative evaluation of ultrasound-mediated cellular uptake of a fluorescent model drug.

Mol Imaging Biol 2013 Oct;15(5):523-33

Laboratoire IMF UMR 5231 CNRS, Université Bordeaux 2, Bordeaux, France,

Purpose: This study aims to quantitatively analyze cellular uptake following local ultrasound (US)-mediated cell permeabilization.

Procedures: A 2 μM cell-impermeable dye Sytox Green was co-injected with 3 × 10(7) microbubbles in the presence of C6 rat glioblastoma cell monolayer in total volume of 10 ml. A 5.8-mm diameter mono-element US transducer was positioned at a distance of 8 mm to the Opticell® membrane. Acoustical pressure of pulsed US was varied from 0.62 MPa peak-to-peak (p-p) to 1.25 MPa p-p. Large field of view (FOV = 15 × 15 mm) 22 × 22 mosaic acquisitions were done under epifluorescence Leica DMR microscope and analyzed in Metamorph software to evaluate cell density as well as model drug uptake percentage.

Results: The size of acoustical field of the transducer closely matches the spatial pattern of the model drug internalized into the cells by US. Maximum of uptake percentage (42 ± 15 %) was found at 0.88 MPa p-p.

Conclusions: Spatial aspect of US-mediated model drug uptake has been quantitatively evaluated on adherent cells using robust 2D-mapping approach.
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http://dx.doi.org/10.1007/s11307-013-0615-1DOI Listing
October 2013

Neurexin-neuroligin adhesions capture surface-diffusing AMPA receptors through PSD-95 scaffolds.

J Neurosci 2011 Sep;31(38):13500-15

Interdisciplinary Institute of Neurosciences, CNRS, UMR 5297, Université de Bordeaux, 33077 Bordeaux, France.

The mechanisms governing the recruitment of functional glutamate receptors at nascent excitatory postsynapses following initial axon-dendrite contact remain unclear. We examined here the ability of neurexin/neuroligin adhesions to mobilize AMPA-type glutamate receptors (AMPARs) at postsynapses through a diffusion/trap process involving the scaffold molecule PSD-95. Using single nanoparticle tracking in primary rat and mouse hippocampal neurons overexpressing or lacking neuroligin-1 (Nlg1), a striking inverse correlation was found between AMPAR diffusion and Nlg1 expression level. The use of Nlg1 mutants and inhibitory RNAs against PSD-95 demonstrated that this effect depended on intact Nlg1/PSD-95 interactions. Furthermore, functional AMPARs were recruited within 1 h at nascent Nlg1/PSD-95 clusters assembled by neurexin-1β multimers, a process requiring AMPAR membrane diffusion. Triggering novel neurexin/neuroligin adhesions also caused a depletion of PSD-95 from native synapses and a drop in AMPAR miniature EPSCs, indicating a competitive mechanism. Finally, both AMPAR level at synapses and AMPAR-dependent synaptic transmission were diminished in hippocampal slices from newborn Nlg1 knock-out mice, confirming an important role of Nlg1 in driving AMPARs to nascent synapses. Together, these data reveal a mechanism by which membrane-diffusing AMPARs can be rapidly trapped at PSD-95 scaffolds assembled at nascent neurexin/neuroligin adhesions, in competition with existing synapses.
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http://dx.doi.org/10.1523/JNEUROSCI.6439-10.2011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6623291PMC
September 2011

In planta quantification of endoreduplication using fluorescent in situ hybridization (FISH).

Plant J 2011 Jun 5;66(6):1089-99. Epub 2011 Apr 5.

Institut National de la Recherche Agronomique (INRA), Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, BP 81, F-33883 Villenave d'Ornon Cedex, France.

Endopolyploidy, i.e. amplification of the genome in the absence of mitosis, occurs in many plant species and happens along with organ and cell differentiation. Deciphering the functional roles of endopolyploidy is hampered by the fact that polyploid tissues generally comprise cells with various ploidy levels. In some fleshy fruits (amongst them tomato fruit) the ploidy levels present at the end of development range from 2C to 256C in the same tissue. To investigate the temporal and spatial distribution of endopolyploidy it is necessary to address the DNA content of individual nuclei in situ. Conventional methods such as fluorometry or densitometry can be used for some tissues displaying favorable characteristics, e.g. small cells, small nuclei, organization in a monolayer, but high levels of varying polyploidy are usually associated with large sizes of nuclei and cells, in a complex three dimensional (3-D) organization of the tissues. The conventional methods are inadequate for such tissue, becoming semi-quantitative and imprecise. We report here the development of a new method based on fluorescent in situ bacterial artificial chromosome hybridizations that allows the in situ determination of the DNA ploidy level of individual nuclei. This method relies on the counting of hybridization signals and not on intensity measurements and is expected to provide an alternative method for mapping endopolyploidy patterns in mature, 3-D organized plant tissues as illustrated by the analysis of ploidy level and cell size in pericarp from mature green tomato fruit.
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http://dx.doi.org/10.1111/j.1365-313X.2011.04568.xDOI Listing
June 2011

Biomimetic divalent ligands for the acute disruption of synaptic AMPAR stabilization.

Nat Chem Biol 2011 Feb 26;7(2):81-91. Epub 2010 Dec 26.

Department of Chemistry and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.

The interactions of the AMPA receptor (AMPAR) auxiliary subunit Stargazin with PDZ domain-containing scaffold proteins such as PSD-95 are critical for the synaptic stabilization of AMPARs. To investigate these interactions, we have developed biomimetic competing ligands that are assembled from two Stargazin-derived PSD-95/DLG/ZO-1 (PDZ) domain-binding motifs using 'click' chemistry. Characterization of the ligands in vitro and in a cellular FRET-based model revealed an enhanced affinity for the multiple PDZ domains of PSD-95 compared to monovalent peptides. In cultured neurons, the divalent ligands competed with transmembrane AMPAR regulatory protein (TARP) for the intracellular membrane-associated guanylate kinase resulting in increased lateral diffusion and endocytosis of surface AMPARs, while showing strong inhibition of synaptic AMPAR currents. This provides evidence for a model in which the TARP-containing AMPARs are stabilized at the synapse by engaging in multivalent interactions. In light of the prevalence of PDZ domain clusters, these new biomimetic chemical tools could find broad application for acutely perturbing multivalent complexes.
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http://dx.doi.org/10.1038/nchembio.498DOI Listing
February 2011

Glucosylceramide biosynthesis is involved in Golgi morphology and protein secretion in plant cells.

Traffic 2010 Apr 17;11(4):479-90. Epub 2009 Dec 17.

Université V. Segalen Bordeaux 2, Laboratoire de Biogenèse Membranaire, CNRS UMR 5200, 146, rue Léo Saignat, 33076 Bordeaux Cedex, France.

Lipids have an established role as structural components of membranes or as signalling molecules, but their role as molecular actors in protein secretion is less clear. The complex sphingolipid glucosylceramide (GlcCer) is enriched in the plasma membrane and lipid microdomains of plant cells, but compared to animal and yeast cells, little is known about the role of GlcCer in plant physiology. We have investigated the influence of GlcCer biosynthesis by glucosylceramide synthase (GCS) on the efficiency of protein transport through the plant secretory pathway and on the maintenance of normal Golgi structure. We determined that GlcCer is synthesized at the beginning of the plant secretory pathway [mainly endoplasmic reticulum (ER)] and that D,L-threo-1-phenyl-2-decanoyl amino-3-morpholino-propanol (PDMP) is a potent inhibitor of plant GCS activity in vitro and in vivo. By an in vivo confocal microscopy approach in tobacco leaves infiltrated with PDMP, we showed that the decrease in GlcCer biosynthesis disturbed the transport of soluble and membrane secretory proteins to the cell surface, as these proteins were partly retained intracellularly in the ER and/or Golgi. Electron microscopic observations of Arabidopsis thaliana root cells after high-pressure freezing and freeze substitution evidenced strong morphological changes in the Golgi bodies, pointing to a link between decreased protein secretion and perturbations of Golgi structure following inhibition of GlcCer biosynthesis in plant cells.
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http://dx.doi.org/10.1111/j.1600-0854.2009.01030.xDOI Listing
April 2010

Probing the dynamics of protein-protein interactions at neuronal contacts by optical imaging.

Chem Rev 2008 May 1;108(5):1565-87. Epub 2008 May 1.

CNRS UMR 5091, Institut Magendie, Université Bordeaux 2, 33077 Bordeaux, France.

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http://dx.doi.org/10.1021/cr078204mDOI Listing
May 2008

Effect of infusing rat monoclonal antibodies to the murine GPIb-IX-V complex on platelet and megakaryocyte morphology in mice.

Platelets 2003 Feb;14(1):35-45

UMR 5533 CNRS, Hôpital Cardiologique, Pessac, France.

In the Bernard-Soulier syndrome, the absence of GPIb-IX-V leads to thrombocytopenia and giant platelets. In autoimmune thrombocytopenia in man, anti-platelet antibodies are associated with changes in megakaryocyte (MK) morphology and platelet size heterogeneity. We have compared the ultrastructural changes in mature MK following the infusion of rat monoclonal antibodies (MoAbs) to different epitopes of the murine GPIb-IX-V complex in mice. Blood and marrow samples were examined during both the acute thrombocytopenic phase and during the recovery phase. A MoAb to GPV induced neither thrombocytopenia nor changes in platelet morphology. During the acute thrombocytopenic phase with anti-GPIbalpha MoAbs, the size of residual platelets was heterogeneous and included large forms and platelets with few granules. During recovery, platelet size heterogeneity continued, and some platelets showed signs of activation. But only rare platelets were giant forms with ultrastructural defects resembling BSS. Megakaryocytopoiesis during acute thrombocytopenia was already abnormal, with some mature cells often showing vacuoles and an irregular development of the demarcation membrane system which varied in extent. These changes continued into the recovery phase. The anti-GPV MoAb had no effect on MK. Thus, anti-platelet antibodies can induce a different medullary response even when binding to the same receptor.
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February 2003

Immunolocalization of P2Y1 and TPalpha receptors in platelets showed a major pool associated with the membranes of alpha -granules and the open canalicular system.

Blood 2003 Feb 10;101(4):1400-8. Epub 2002 Oct 10.

Centre National de la Recherche Scientifique (CNRS), Hôpital Cardiologique, Pessac, France.

P2Y(1) and thromboxane-prostanoid-alpha (TPalpha) receptors on platelets belong to the G-protein-coupled 7-transmembrane domain family. They transmit signals for shape change, mobilization of calcium, and platelet aggregation. Immunogold labeling with a monoclonal antibody (MoAb) to the amino-terminal domain of P2Y(1) and a polyclonal antibody to the C-terminal domain of TPalpha revealed that while present at the platelet surface, both receptors were abundantly represented inside the platelet. Specifically, receptors were found in membranes of alpha-granules and elements of the open-canalicular system. A similar organization was found in mature megakaryocytes. Activation of platelets by adenosine diphosphate (ADP) and the thromboxane A(2) (TXA(2)) analog, I-BOP [1S-(1 alpha,2 beta(5Z),3 alpha-(1E,3S)4 alpha)-7-(3-(3- hydroxy-4-(p-iodophenoxy)-1-butenyl)-7-oxabicyclo(2.2.1)hept-2-yl)-5-heptenoic acid], increased the labeling of both P2Y(1) and TPalpha at the surface and in intracellular pools, suggesting that activation resulted in greater antibody accessibility to the receptor. A return to a platelet discoid shape and to basal values of labeling accompanied receptor desensitization. Platelets lacking the P2Y(12) ADP receptor normally expressed P2Y(1) and TPalpha, both before and after activation. Studies with the anti-ligand-induced binding site (anti-LIBS) MoAb, AP-6, confirmed that stored fibrinogen associated with internal pools of alpha(IIb)beta(3) at the start of secretion in a microenvironment containing agonist receptors. Pharmacologic antagonism of ADP or TXA(2) receptors in antithrombotic therapy may need to take into account blockade of internal receptor pools.
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http://dx.doi.org/10.1182/blood-2002-02-0642DOI Listing
February 2003

A Ser752-->Pro substitution in the cytoplasmic domain of beta3 in a Glanzmann thrombasthenia variant fails to prevent interactions between the alphaIIbbeta3 integrin and the platelet granule pool of fibrinogen.

Br J Haematol 2002 Sep;118(4):1143-51

UMR 5533 CNRS, Hôpital Cardiologique, Pessac and Académie des Sciences, and Institut de France, Paris, France.

A Glanzmann thrombasthenia variant with a beta3 Ser752-->Pro cytoplasmic domain substitution has platelets that fail to aggregate or bind soluble fibrinogen (Fg) after activation. Despite this, Fg is normally present in the alpha-granules. We have used immunoelectron microscopy to examine the reactivity of Fg with the different pools of alphaIIbbeta3 in the patient's platelets. Immunogold labelling was performed on cryosections using an anti-ligand-induced binding site (LIBS) monoclonal antibody (mAb), which binds to alphaIIbbeta3 only when Fg is bound, or a mixture of two anti-receptor-induced binding site (RIBS) mAbs that specifically recognize receptor-bound Fg. Labelling of the alpha-granule membrane and channels of the surface-connected canalicular system in unstimulated platelets confirmed that the mutated alphaIIbbeta3 retains the capacity to transport Fg. When the patient's platelets were stimulated with ADP in the presence of Fg, as expected there was a much-decreased activation of surface-exposed alphaIIbbeta3. However, thrombin-induced activation was associated with both secretion and a rapid increase in the labelling of internal membrane systems by anti-RIBS and anti-LIBS mAbs, with mobilization of the internal Fg pool. Yet labelling on the surface of the patient's platelets was transient. Our studies implied that alphaIIbbeta3 in platelets may bind fibrinogen in different activation states and that this patient specifically lacked high-affinity binding.
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http://dx.doi.org/10.1046/j.1365-2141.2002.03758.xDOI Listing
September 2002

Absence of GPIbalpha is responsible for aberrant membrane development during megakaryocyte maturation: ultrastructural study using a transgenic model.

Exp Hematol 2002 Apr;30(4):352-60

UMR 5533 CNRS, Laboratoire d'Hématologie, Hôpital Cardiologique, Avenue de Magellan, 33604 Pessac, France.

Objective: The glycoprotein Ib/IX/V complex (GPIb-IX-V) mediates platelet attachment to von Willebrand factor in exposed subendothelium. Molecular defects in the genes for GPIbalpha, GPIbbeta, and GPIX give rise to the Bernard-Soulier syndrome, in which thrombocytopenia and giant platelets suggest that this receptor also is involved in platelet production. To study how giant platelets are produced in vivo, we used a model of GPIbalpha-deficient mice (GPIbalpha(null)) and mice rescued with the human GPIbalpha transgene (GPIbalpha(null;hTg)).

Materials And Methods: Using electron microscopy and immunogold labeling, we examined megakaryocytopoiesis in the bone marrow of these mice and developed a method to quantify the membranes of megakaryocytes (MK) and proplatelets by computer analysis.

Results: Abnormal membrane development in the perinuclear zone was found in immature MK of GPIbalpha(null) mice. This led to a poorly developed demarcation membrane system and other ultrastructural changes. As a result, well-organized platelet territories were rarely seen within the cytoplasm of mature MK. Membrane quantification confirmed that MK of GPIbalpha(null) mice had a reduced internal membrane pool. Whereas these MK normally crossed the endothelial barrier, their migration was accompanied by the production of unusually large MK fragments or proplatelets in the vascular sinus with an approximately 50% decrease in internal membrane content compared to wild-type. In the rescued GPIbalpha(null;hTg) model, GPIbalpha was normally localized in MK, and there was a total correction of the ultrastructural defects.

Conclusions: GPIbalpha is essential for membrane development and distribution in maturing MK. Its absence leads to abnormal partitioning of the membrane systems and abnormal proplatelet production.
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http://dx.doi.org/10.1016/s0301-472x(02)00774-9DOI Listing
April 2002

A prototypic platelet septin and its participation in secretion.

Proc Natl Acad Sci U S A 2002 Mar;99(5):3064-9

Division of Experimental Hemostasis and Thrombosis, Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.

Studies are presented characterizing platelet CDCrel-1, a protein expressed to high levels by megakaryocytes and belonging to a family of conserved proteins, termed septin. Septin filaments originally were identified in yeast as essential for budding but have become increasingly associated with processes in higher eukaryotic cells involving active membrane movement such as cytokinesis and vesicle trafficking. Direct proof of an in vivo function for septins in higher eukaryotes is limited to the characterization of the Drosophila septin, termed PNUT. We present studies identifying platelet CDCrel-1 as a protein kinase substrate in the presence of known platelet agonists. The immunopurification of CDCrel-1 revealed it to be part of a macromolecular complex containing a protein involved in platelet secretion, syntaxin 4. Moreover, CDCrel-1 was localized in situ to areas surrounding platelet-storage granules. The relevance of CDCrel-1 to normal platelet function was established with the characterization of platelets from a CDCrel-1(Null) mouse. As compared with platelets from wild-type littermates, CDCrel-1(Null) platelets aggregate and release stored [14C]serotonin in the presence of subthreshold levels of collagen. These results provide new insights into the mechanisms regulating platelet secretion and identify platelet septins as a protein family contributing to membrane trafficking within the megakaryocyte and platelet.
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http://dx.doi.org/10.1073/pnas.052715199DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC122473PMC
March 2002

Paradoxical platelet activation was not observed on dissociation of abciximab from GpIIb-IIIa complexes.

Thromb Haemost 2002 Feb;87(2):317-22

UMR 5533 CNRS, Hĵpital Cardiologique, Pessac, France.

The ability of abciximab to bind and dissociate from platelets raises the question of the conformational state of GPIIb-IIIa complexes losing abciximab and the risk of paradoxical drug-induced platelet activation. Platelets incubated with abciximab and mixed in vitro with c7E3 Fab-free platelets lost the drug to the new platelets giving a single platelet population with a unimodal abciximab distribution within 17 h. Prelabeling the receiving platelets with phycoerythrin-labeled anti-GPIb monoclonal antibody (MoAb), permitted their identification by flow cytometry. Binding of PAC-1 and AP6, two MoAbs specific for activated GPIIb-IIIa, was then assessed to both losing and receiving platelet populations during transfer of abciximab. The subpopulation losing c7E3 Fab failed to show increased binding of these MoAbs. However, PAC-1 binding increased in both subpopulations after addition of ADP. Thus GPIIb-IIIa complexes are not in an activated state after dissociation of abciximab unless there is an additional source of activation.
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February 2002