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1710 references
Boulanger J, Kervrann C, Bouthemy P, Elbau P, Sibarita JB, Salamero J. Patch-based nonlocal functional for denoising fluorescence microscopy image sequences. IEEE Trans Med Imaging. 2010 Feb;29(2):442-54.. 2010
IF : 4.004
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| National Collaboration |
- Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. |
| Abstract |
We present a nonparametric regression method for denoising 3-D image sequences acquired via fluorescence microscopy. The proposed method exploits the redundancy of the 3-D+time information to improve the signal-to-noise ratio of images corrupted by Poisson-Gaussian noise. A variance stabilization transform is first applied to the image-data to remove the dependence between the mean and variance of intensity values. This preprocessing requires the knowledge of parameters related to the acquisition system, also estimated in our approach. In a second step, we propose an original statistical patch-based framework for noise reduction and preservation of space-time discontinuities. In our study, discontinuities are related to small moving spots with high velocity observed in fluorescence video-microscopy. The idea is to minimize an objective nonlocal energy functional involving spatio-temporal image patches. The minimizer has a simple form and is defined as the weighted average of input data taken in spatially-varying neighborhoods. The size of each neighborhood is optimized to improve the performance of the pointwise estimator. The performance of the algorithm (which requires no motion estimation) is then evaluated on both synthetic and real image sequences using qualitative and quantitative criteria. |
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Bannai H, Lévi S, Schweizer C, Inoue T, Launey T, Racine V, Sibarita JB, Mikoshiba K, Triller A. Activity-dependent tuning of inhibitory neurotransmission based on GABAAR diffusion dynamics.
Neuron. 2009 Jun 11;62(5):670-82.. 2009
original article. IF : 14.170
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| National Collaboration |
- Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. |
| Abstract |
An activity-dependent change in synaptic efficacy is a central tenet in learning, memory, and pathological states of neuronal excitability. The lateral diffusion dynamics of neurotransmitter receptors are one of the important parameters regulating synaptic efficacy. We report here that neuronal activity modifies diffusion properties of type-A GABA receptors (GABA(A)R) in cultured hippocampal neurons: enhanced excitatory synaptic activity decreases the cluster size of GABA(A)Rs and reduces GABAergic mIPSC. Single-particle tracking of the GABA(A)R gamma2 subunit labeled with quantum dots reveals that the diffusion coefficient and the synaptic confinement domain size of GABA(A)R increases in parallel with neuronal activity, depending on Ca(2+) influx and calcineurin activity. These results indicate that GABA(A)R diffusion dynamics are directly linked to rapid and plastic modifications of inhibitory synaptic transmission in response to changes in intracellular Ca(2+) concentration. This transient activity-dependent reduction of inhibition would favor the onset of LTP during conditioning. |
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Montagnac G, Sibarita JB, Loubéry S, Daviet L, Romao M, Raposo G, Chavrier P. ARF6 Interacts with JIP4 to control a motor switch mechanism regulating endosome traffic in cytokinesis. Curr Biol. 2009 Feb 10;19(3):184-95.. 2009
original article. IF : 10.777
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| National Collaboration |
- Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. |
| Abstract |
BACKGROUND: Recent work has highlighted the importance of the recycling of endocytic membranes to the intercellular bridge for completion of cytokinesis in animal cells. ADP-ribosylation factor 6 (ARF6), which localizes to the plasma membrane and endosomal compartments, regulates endocytic recycling to the bridge during cytokinesis and is required for abscission. RESULTS: Here, we report that the JNK-interacting proteins JIP3 and JIP4, two highly related scaffolding proteins for JNK signaling modules, also acting as binding partners of kinesin-1 and dynactin complex, can function as downstream effectors of ARF6. In vitro, binding of GTP-ARF6 to the second leucine zipper domain of JIP3 and JIP4 interferes with JIPs' association with kinesin-1, whereas it favors JIPs' interaction with the dynactin complex. With protein silencing by small interfering RNA and dominant inhibition approaches, we show that ARF6, JIP4, kinesin-1, and the dynactin complex control the trafficking of recycling endosomes in and out of the intercellular bridge and are necessary for abscission. CONCLUSION: Our findings reveal a novel function for ARF6 as a regulatory switch for motor proteins of opposing direction that controls trafficking of endocytic vesicles within the intercellular bridge in a mechanism required for abscission. |
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Dimitrov A, Paupe V, Gueudry C, Sibarita JB, Raposo G, Vielemeyer O, Gilbert T, Csaba Z, Attie-Bitach T, Cormier-Daire V, Gressens P, Rustin P, Perez F, El Ghouzzi V. The gene responsible for Dyggve-Melchior-Clausen syndrome encodes a novel peripheral membrane protein dynamically associated with the Golgi apparatus. Hum Mol Genet. 2009 Feb 1;18(3):440-53.Erratum in: Hum Mol Genet. 2009 May 1;18(9):1714-6.. 2009
original article. IF : 7.249
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| National Collaboration |
- Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. |
| Abstract |
Dyggve-Melchior-Clausen dysplasia (DMC) is a rare inherited dwarfism with severe mental retardation due to mutations in the DYM gene which encodes Dymeclin, a 669-amino acid protein of yet unknown function. Despite a high conservation across species and several predicted transmembrane domains, Dymeclin could not be ascribed to any family of proteins. Here we show, using in situ hybridization, that DYM is widely expressed in human embryos, especially in the cortex, the hippocampus and the cerebellum. Both the endogenous and the recombinant protein fused to green fluorescent protein co-localized with Golgi apparatus markers. Electron microscopy revealed that Dymeclin associates with the Golgi apparatus and with transitional vesicles of the reticulum-Golgi interface. Moreover, permeabilization assays revealed that Dymeclin is not a transmembrane but a peripheral protein of the Golgi apparatus as it can be completely released from the Golgi after permeabilization of the plasma membrane. Time lapse confocal microscopy experiments on living cells further showed that the protein shuttles between the cytosol and the Golgi apparatus in a highly dynamic manner and recognizes specifically a subset of mature Golgi membranes. Finally, we found that DYM mutations associated with DMC result in mis-localization and subsequent degradation of Dymeclin. These data indicate that DMC results from a loss-of-function of Dymeclin, a novel peripheral membrane protein which shuttles rapidly between the cytosol and mature Golgi membranes and point out a role of Dymeclin in cellular trafficking. |
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Sakurai-Yageta M, Recchi C, Le Dez G, Sibarita JB, Daviet L, Camonis J, D'Souza-Schorey C, Chavrier P. The interaction of IQGAP1 with the exocyst complex is required for tumor cell invasion downstream of Cdc42 and RhoA. J Cell Biol. 2008 Jun 16;181(6):985-98.. 2008
original article. IF : 9.120
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| National Collaboration |
- Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. |
| Abstract |
Invadopodia are actin-based membrane protrusions formed at contact sites between invasive tumor cells and the extracellular matrix with matrix proteolytic activity. Actin regulatory proteins participate in invadopodia formation, whereas matrix degradation requires metalloproteinases (MMPs) targeted to invadopodia. In this study, we show that the vesicle-tethering exocyst complex is required for matrix proteolysis and invasion of breast carcinoma cells. We demonstrate that the exocyst subunits Sec3 and Sec8 interact with the polarity protein IQGAP1 and that this interaction is triggered by active Cdc42 and RhoA, which are essential for matrix degradation. Interaction between IQGAP1 and the exocyst is necessary for invadopodia activity because enhancement of matrix degradation induced by the expression of IQGAP1 is lost upon deletion of the exocyst-binding site. We further show that the exocyst and IQGAP1 are required for the accumulation of cell surface membrane type 1 MMP at invadopodia. Based on these results, we propose that invadopodia function in tumor cells relies on the coordination of cytoskeletal assembly and exocytosis downstream of Rho guanosine triphosphatases. |
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Romao M, Tanaka K, Sibarita JB, Ly-Hartig NT, Tanaka TU, Antony C. Three-dimensional electron microscopy analysis of ndc10-1 mutant reveals an aberrant organization of the mitotic spindle and spindle pole body defects in Saccharomyces cerevisiae.
J Struct Biol. 2008 Jul;163(1):18-28.. 2008
original article. IF : 4.059
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| National Collaboration |
- Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. |
| Abstract |
Kinetochore components play a major role in regulating the transmission of genetic information during cell division. Ndc10p, a kinetochore component of the essential CBF3 complex in budding yeast is required for chromosome attachment to the mitotic spindle. ndc10-1 mutant was shown to display chromosome mis-segregation as well as an aberrant mitotic spindle (Goh and Kilmartin, 1993). In addition, Ndc10p localizes along the spindle microtubules (Muller-Reichert et al., 2003). To further understand the role of Ndc10p in the mitotic apparatus, we performed a three-dimensional electron microscopy (EM) reconstruction of mitotic spindles from serial sections of cryo-immobilized ndc10-1 mutant cells. This analysis reveals a dramatic reduction in the number of microtubules present in the half-spindle, which is connected to the newly formed spindle pole body (SPB) in ndc10-1 cells. Moreover, in contrast to wild-type (WT) cells, ndc10-1 cells showed a significantly lower signal intensity of the SPB components Spc42p and Spc110p fused with GFP, in mother cell bodies compared with buds. A subsequent EM analysis also showed clear defects in the newly formed SPB, which remains in the mother cell during anaphase. These results suggest that Ndc10p is required for maturation of the newly formed SPB. Intriguingly, mutations in other kinetochore components, ndc80-1 and spc24-1, showed kinetochore detachment from the spindle, similar to ndc10-1, but did not display defects in SPBs. This suggests that unattached kinetochores are not sufficient to cause SPB defects in ndc10-1 cells. We propose that Ndc10p, alongside its role in kinetochore-microtubule interaction, is also essential for SPB maturation and mitotic spindle integrity. |
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De Mey JR, Kessler P, Dompierre J, Cordelières FP, Dieterlen A, Vonesch JL, Sibarita JB. Fast 4D Microscopy.
Methods Cell Biol. 2008;85:83-112.. 2008
original article. IF : 1.595
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| National Collaboration |
- Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. |
| Abstract |
Many cellular processes involve fast movements of weakly labeled cellular structures in all directions, which should be recorded in 3D time-lapse microscopy (4D microscopy). This chapter introduces fast 4D imaging, which is used for sampling the cell's volume by collecting focal planes in time-lapse mode as rapidly as possible, without perturbing the sample by strong illumination. The final images should contain sufficient contrast allowing for the isolation of structures of interest by segmentation and the analysis of their intracellular movements by tracking. Because they are the most sensitive, systems using wide-field microscopy and deconvolution techniques are discussed in greater depth. We discuss important points to consider, including system components and multifunctionality, spatial resolution and sampling conditions, and mechanical and optical stability and how to test for it. We consider image formation using high numerical aperture optics and discuss the influence of optical blur and noise on image formation of living cells. Spherical aberrations, their consequences for axial image quality, and their impact on the success of deconvolution of low intensity image stacks are explained in detail. Simple protocols for acquiring and treating point spread functions (PSFs) and live cells are provided. A compromise for counteracting spherical aberration involving the use of a kit of immersion oils for PSF and cell acquisition is illustrated. Recommendations for evaluating acquisition conditions and deconvolution paramete |
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Moutsimilli L, Farley S, El Khoury MA, Chamot C, Sibarita JB, Racine V, El Mestikawy S, Mathieu F, Dumas S, Giros B, Tzavara ET.
Antipsychotics increase vesicular glutamate transporter 2 (VGLUT2) expression in thalamolimbic pathways.
Neuropharmacology. 2008 Mar;54(3):497-508.. 2008
original article. IF : 3.383
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| National Collaboration |
- Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. |
| Abstract |
Recently the two vesicular-glutamate-transporters VGLUT1 and VGLUT2 have been cloned and characterized. VGLUT1 and VGLUT2 together label all glutamatergic neurons, but because of their distinct expression patterns in the brain they facilitate our ability to define between a VGLUT1-positive cortical and a VGLUT2-positive subcortical glutamatergic systems. We have previously demonstrated an increased cortical VGLUT1 expression as marker of antidepressant activity. Here, we assessed the effects of different psychotropic drugs on brain VGLUT2 mRNA and protein expression. The typical antipsychotic haloperidol, and the atypicals clozapine and risperidone increased VGLUT2 mRNA selectively in the central medial/medial parafascicular, paraventricular and intermediodorsal thalamic nuclei; VGLUT2 protein was accordingly amplified in paraventricular and ventral striatum and in prefrontal cortex. The antidepressants fluoxetine and desipramine and the sedative anxiolytic diazepam had no effect. These results highlight the implication of thalamo-limbic glutamatergic pathways in the action of antipsychotics. Increased VGLUT2 expression in these neurons might constitute a marker for antipsychotic activity and subcortical glutamate neurotransmission might be a possible novel target for future generation antipsychotics. |
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Desnos C, Huet S, Fanget I, Chapuis C, Böttiger C, Racine V, Sibarita JB, Henry JP, Darchen F. Myosin va mediates docking of secretory granules at the plasma membrane.
J Neurosci. 2007 Sep 26;27(39):10636-45.. 2007
original article. IF : 7.490
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| National Collaboration |
- Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. |
| Abstract |
Myosin Va (MyoVa) is a prime candidate for controlling actin-based organelle motion in neurons and neuroendocrine cells. Its function in secretory granule (SG) trafficking was investigated in enterochromaffin cells by wide-field and total internal reflection fluorescence microscopy. The distribution of endogenous MyoVa partially overlapped with SGs and microtubules. Impairing MyoVa function by means of a truncated construct (MyoVa tail) or RNA interference prevented the formation of SG-rich regions at the cell periphery and reduced SG density in the subplasmalemmal region. Individual SG trajectories were tracked to analyze SG mobility. A wide distribution of their diffusion coefficient, D(xy), was observed. Almost immobile SGs (D(xy) < 5 x 10(-4) microm2 x s(-1)) were considered as docked at the plasma membrane based on two properties: (1) SGs that undergo exocytosis have a D(xy) below this threshold value for at least 2 s before fusion; (2) a negative autocorrelation of the vertical motion was found in subtrajectories with a D(xy) below the threshold. Using this criterion of docking, we found that the main effect of MyoVa inhibition was to reduce the number of docked granules, leading to reduced secretory responses. Surprisingly, this reduction was not attributable to a decreased transport of SGs toward release sites. In contrast, MyoVa silencing reduced the occurrence of long-lasting, but not short-lasting, docking periods. We thus propose that, despite its known motor activity, MyoVa directly mediates stable attachment of SGs at the plasma membrane. |
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Vascotto F, Lankar D, Faure-André G, Vargas P, Diaz J, Le Roux D, Yuseff MI, Sibarita JB, Boes M, Raposo G, Mougneau E, Glaichenhaus N, Bonnerot C, Manoury B, Lennon-Duménil AM. The actin-based motor protein myosin II regulates MHC class II trafficking and BCR-driven antigen presentation.
J Cell Biol. 2007 Mar 26;176(7):1007-19.. 2007
original article. IF : 9.598
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| National Collaboration |
- Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. |
| Abstract |
Antigen (Ag) capture and presentation onto major histocompatibility complex (MHC) class II molecules by B lymphocytes is mediated by their surface Ag receptor (B cell receptor [BCR]). Therefore, the transport of vesicles that carry MHC class II and BCR-Ag complexes must be coordinated for them to converge for processing. In this study, we identify the actin-associated motor protein myosin II as being essential for this process. Myosin II is activated upon BCR engagement and associates with MHC class II-invariant chain complexes. Myosin II inhibition or depletion compromises the convergence and concentration of MHC class II and BCR-Ag complexes into lysosomes devoted to Ag processing. Accordingly, the formation of MHC class II-peptides and subsequent CD4 T cell activation are impaired in cells lacking myosin II activity. Therefore, myosin II emerges as a key motor protein in BCR-driven Ag processing and presentation. |
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