PubMed Central (PMC3 - NLM DTD)
(2,081,148 recursos)
Archive of life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).
Mostrando recursos 21 - 40 de 9,978
21.
Role of Numb in Dendritic Spine Development with a Cdc42 GEF Intersectin and EphB2D? - Nishimura, Takashi; Yamaguchi, Tomoya; Tokunaga, Akinori; Hara, Akitoshi; Hamaguchi, Tomonari; Kato, Katsuhiro; Iwamatsu, Akihiro; Okano, Hideyuki; Kaibuchi, Kozo
Numb has been implicated in cortical neurogenesis during nervous system development, as a result of its asymmetric partitioning and antagonizing Notch signaling. Recent studies have revealed that Numb functions in clathrin-dependent endocytosis by binding to the AP-2 complex. Numb is also expressed in postmitotic neurons and plays a role in axonal growth. However, the functions of Numb in later stages of neuronal development remain unknown. Here, we report that Numb specifically localizes to dendritic spines in cultured hippocampal neurons and is implicated in dendritic spine morphogenesis, partially through the direct interaction with intersectin, a Cdc42 guanine nucleotide exchange factor (GEF)....
22.
RAB-10 Is Required for Endocytic Recycling in the Caenorhabditis elegans IntestineD? - Chen, Carlos Chih-Hsiung; Schweinsberg, Peter J.; Vashist, Shilpa; Mareiniss, Darren P.; Lambie, Eric J.; Grant, Barth D.
The endocytic pathway of eukaryotes is essential for the internalization and trafficking of macromolecules, fluid, membranes, and membrane proteins. One of the most enigmatic aspects of this process is endocytic recycling, the return of macromolecules (often receptors) and fluid from endosomes to the plasma membrane. We have previously shown that the EH-domain protein RME-1 is a critical regulator of endocytic recycling in worms and mammals. Here we identify the RAB-10 protein as a key regulator of endocytic recycling upstream of RME-1 in polarized epithelial cells of the Caenorhabditis elegans intestine. rab-10 null mutant intestinal cells accumulate abnormally abundant RAB-5-positive early...
23.
Establishment of Polarity during Organization of the Acentrosomal Plant Cortical Microtubule ArrayD?V? - Dixit, Ram; Chang, Eric; Cyr, Richard
The plant cortical microtubule array is a unique acentrosomal array that is essential for plant morphogenesis. To understand how this array is organized, we exploited the microtubule (+)-end tracking activity of two Arabidopsis EB1 proteins in combination with FRAP (fluorescence recovery after photobleaching) experiments of GFP-tubulin to examine the relationship between cortical microtubule array organization and polarity. Significantly, our observations show that the majority of cortical microtubules in ordered arrays, within a particular cell, face the same direction in both Arabidopsis plants and cultured tobacco cells. We determined that this polar microtubule coalignment is at least partially due to a...
24.
Characterization of the Yeast Amphiphysins Rvs161p and Rvs167p Reveals Roles for the Rvs Heterodimer In Vivo - Friesen, Helena; Humphries, Christine; Ho, Yuen; Schub, Oliver; Colwill, Karen; Andrews, Brenda
We have used comprehensive synthetic lethal screens and biochemical assays to examine the biological role of the yeast amphiphysin homologues Rvs161p and Rvs167p, two proteins that play a role in regulation of the actin cytoskeleton, endocytosis, and sporulation. We found that unlike some forms of amphiphysin, Rvs161p-Rvs167p acts as an obligate heterodimer during vegetative growth and neither Rvs161p nor Rvs167p forms a homodimer in vivo. RVS161 and RVS167 have an identical set of 49 synthetic lethal interactions, revealing functions for the Rvs proteins in cell polarity, cell wall synthesis, and vesicle trafficking as well as a shared role in mating....
25.
The Heat-Shock Protein Apg-2 Binds to the Tight Junction Protein ZO-1 and Regulates Transcriptional Activity of ZONAB - Tsapara, Anna; Matter, Karl; Balda, Maria S.
The tight junction adaptor protein ZO-1 regulates intracellular signaling and cell proliferation. Its Src homology 3 (SH3) domain is required for the regulation of proliferation and binds to the Y-box transcription factor ZO-1-associated nucleic acid binding protein (ZONAB). Binding of ZO-1 to ZONAB results in cytoplasmic sequestration and hence inhibition of ZONAB's transcriptional activity. Here, we identify a new binding partner of the SH3 domain that modulates ZO-1ZONAB signaling. Expression screening of a cDNA library with a fusion protein containing the SH3 domain yielded a cDNA coding for Apg-2, a member of the heat-shock protein 110 (Hsp 110) subfamily of...
26.
The Arabidopsis thaliana PARTING DANCERS Gene Encoding a Novel Protein Is Required for Normal Meiotic Homologous RecombinationD? - Wijeratne, Asela J.; Chen, Changbin; Zhang, Wei; Timofejeva, Ljudmilla; Ma, Hong
Recent studies of meiotic recombination in the budding yeast and the model plant Arabidopsis thaliana indicate that meiotic crossovers (COs) occur through two genetic pathways: the interference-sensitive pathway and the interference-insensitive pathway. However, few genes have been identified in either pathway. Here, we describe the identification of the PARTING DANCERS (PTD) gene, as a gene with an elevated expression level in meiocytes. Analysis of two independently generated transferred DNA insertional lines in PTD showed that the mutants had reduced fertility. Further cytological analysis of male meiosis in the ptd mutants revealed defects in meiosis, including reduced formation of chiasmata, the...
27.
Control of Bro1-Domain Protein Rim20 Localization by External pH, ESCRT Machinery, and the Saccharomyces cerevisiae Rim101 Pathway - Boysen, Jacob H.; Mitchell, Aaron P.
Bro1-domain proteins such as yeast Bro1 and mammalian AIP1/Alix are well-established participants in endosome metabolism. The Bro1-domain interacts with endosomal surface protein Snf7/Vps32 in yeast, a subunit of the ESCRT complex. Yeast Bro1-domain protein Rim20 has no role in endosome function, but is required for alkaline pH-stimulated cleavage of transcription factor Rim101. Rim20-GFP is cytoplasmic under acidic conditions but concentrated in punctate foci under alkaline conditions. Bro1-GFP also accumulates in foci, but they are more numerous under acidic than alkaline conditions. Colocalization experiments indicate that some Rim20-GFP foci correspond to Bro1-RFP foci, whereas others do not. Rim8, Rim9, Rim21, Dfg16,...
28.
Actin-based Motility during Endocytosis in Budding YeastV? - Kim, Kyoungtae; Galletta, Brian J.; Schmidt, Kevin O.; Chang, Fanny S.; Blumer, Kendall J.; Cooper, John A.
Actin assembly nucleated by Arp2/3 complex has been implicated in the formation and movement of endocytic vesicles. The dendritic nucleation model has been proposed to account for Arp2/3-mediated actin assembly and movement. Here, we explored the model by examining the role of capping protein in vivo, with quantitative tracking analysis of fluorescence markers for different stages of endocytosis in yeast. Capping protein was most important for the initial movement of endocytic vesicles away from the plasma membrane, which presumably corresponds to vesicle scission and release. The next phase of endosome movement away from the plasma membrane was also affected, but...
29.
Protein Kinase C? Regulates Myosin IIB Phosphorylation, Cellular Localization, and Filament Assembly - Rosenberg, Michael; Ravid, Shoshana
Nonmuscle myosin II is an important component of the cytoskeleton, playing a major role in cell motility and chemotaxis. We have previously demonstrated that, on stimulation with epidermal growth factor (EGF), nonmuscle myosin heavy chain II-B (NMHC-IIB) undergoes a transient phosphorylation correlating with its cellular localization. We also showed that members of the PKC family are involved in this phosphorylation. Here we demonstrate that of the two conventional PKC isoforms expressed by prostate cancer cells, PKC?II and PKC?, PKC? directly phosphorylates NMHC-IIB. Overexpression of wild-type and kinase dead dominant negative PKC? result in both altered NMHC-IIB phosphorylation and subcellular localization....
30.
The Association of Shiga-like Toxin with Detergent-resistant Membranes Is Modulated by Glucosylceramide and Is an Essential Requirement in the Endoplasmic Reticulum for a Cytotoxic Effect - Smith, Daniel C.; Sillence, Daniel J.; Falguières, Thomas; Jarvis, Rosemary M.; Johannes, Ludger; Lord, J. Michael; Platt, Frances M.; Roberts, Lynne M.
Receptor-mediated internalization to the endoplasmic reticulum (ER) and subsequent retro-translocation to the cytosol are essential sequential processes required for the productive intoxication of susceptible mammalian cells by Shiga-like toxin-1 (SLTx). Recently, it has been proposed that the observed association of certain ER-directed toxins and viruses with detergent-resistant membranes (DRM) may provide a general mechanism for their retrograde transport to endoplasmic reticulum (ER). Here, we show that DRM recruitment of SLTx bound to its globotriosylceramide (Gb3) receptor is mediated by the availability of other glycosphingolipids. Reduction in glucosylceramide (GlcCer) levels led to complete protection against SLTx and a reduced cell surface...
31.
Identification of the Junctional Plaque Protein Plakophilin 3 in Cytoplasmic Particles Containing RNA-binding Proteins and the Recruitment of Plakophilins 1 and 3 to Stress GranulesD? - Hofmann, Ilse; Casella, Marialuisa; Schnölzer, Martina; Schlechter, Tanja; Spring, Herbert; Franke, Werner W.
Recent studies on the subcellular distribution of cytoplasmic plaque proteins of intercellular junctions have revealed that a number of such proteins can also occur in the cyto- and the nucleoplasm. This occurrence in different, and distant locations suggest that some plaque proteins play roles in cytoplasmic and nuclear processes in addition to their involvement in cellcell adhesive interactions. Plakophilin (PKP) 3, a member of the arm-repeat family of proteins, occurs, in a diversity of cell types, both as an architectural component in plaques of desmosomes and dispersed in cytoplasmic particles. In immuno-selection experiments using PKP3-specific antibodies, we have identified by...
32.
Differential Distribution of Exosome Subunits at the Nuclear Lamina and in Cytoplasmic FociD?V? - Graham, Amy C.; Kiss, Daniel L.; Andrulis, Erik D.
The exosome complex plays important roles in RNA processing and turnover. Despite significant mechanistic insight into exosome function, we still lack a basic understanding of the subcellular locales where exosome complex biogenesis and function occurs. Here, we employ a panel of Drosophila S2 stable cell lines expressing epitope-tagged exosome subunits to examine the subcellular distribution of exosome complex components. We show that tagged Drosophila exosome subunits incorporate into complexes that recover endogenous nuclear and cytoplasmic exosome subunits. Immunolocalization analyses demonstrate that subsets of both epitope-tagged and endogenous exosome subunits are enriched in discrete subcellular compartments. In particular, dRrp4, dRrp42, dRrp46,...
33.
PGAP2 Is Essential for Correct Processing and Stable Expression of GPI-anchored ProteinsD? - Tashima, Yuko; Taguchi, Ryo; Murata, Chie; Ashida, Hisashi; Kinoshita, Taroh; Maeda, Yusuke
Biosynthesis of glycosylphosphatidylinositol-anchored proteins (GPI-APs) in the ER has been extensively studied, whereas the molecular events during the transport of GPI-APs from the ER to the cell surface are poorly understood. Here, we established new mutant cell lines whose surface expressions of GPI-APs were greatly decreased despite normal biosynthesis of GPI-APs in the ER. We identified a gene responsible for this defect, designated PGAP2 (for Post-GPI-Attachment to Proteins 2), which encoded a Golgi/ER-resident membrane protein. The low surface expression of GPI-APs was due to their secretion into the culture medium. GPI-APs were modified/cleaved by two reaction steps in the mutant...
34.
The V260I Mutation in Fission Yeast ?-Tubulin Atb2 Affects Microtubule Dynamics and EB1-Mal3 Localization and Activates the Bub1 Branch of the Spindle CheckpointD? - Asakawa, Kazuhide; Kume, Kazunori; Kanai, Muneyoshi; Goshima, Tetsuya; Miyahara, Kohji; Dhut, Susheela; Tee, Wee Wei; Hirata, Dai; Toda, Takashi
We have identified a novel temperature-sensitive mutant of fission yeast ?-tubulin Atb2 (atb2-983) that contains a single amino acid substitution (V260I). Atb2-983 is incorporated into the microtubules, and their overall structures are not altered noticeably, but microtubule dynamics is compromised during interphase. atb2-983 displays a high rate of chromosome missegregation and is synthetically lethal with deletions in a subset of spindle checkpoint genes including bub1, bub3, and mph1, but not with mad1, mad2, and mad3. During early mitosis in this mutant, Bub1, but not Mad2, remains for a prolonged period in the kinetochores that are situated in proximity to one...
35.
Proteomic Analysis of the Yeast Mitochondrial Outer Membrane Reveals Accumulation of a Subclass of PreproteinsD? - Zahedi, Rene P.; Sickmann, Albert; Boehm, Andreas M.; Winkler, Christiane; Zufall, Nicole; Schönfisch, Birgit; Guiard, Bernard; Pfanner, Nikolaus; Meisinger, Chris
Mitochondria consist of four compartmentsouter membrane, intermembrane space, inner membrane, and matrixwith crucial but distinct functions for numerous cellular processes. A comprehensive characterization of the proteome of an individual mitochondrial compartment has not been reported so far. We used a eukaryotic model organism, the yeast Saccharomyces cerevisiae, to determine the proteome of highly purified mitochondrial outer membranes. We obtained a coverage of ?85% based on the known outer membrane proteins. The proteome represents a rich source for the analysis of new functions of the outer membrane, including the yeast homologue (Hfd1/Ymr110c) of the human protein causing SjögrenLarsson syndrome. Surprisingly, a...
36.
Chromokinesin Xklp1 Contributes to the Regulation of Microtubule Density and Organization during Spindle Assembly - Castoldi, Mirco; Vernos, Isabelle
Xklp1 is a chromosome-associated kinesin required for Xenopus early embryonic cell division. Function blocking experiments in Xenopus egg extracts suggested that it is required for spindle assembly. We have reinvestigated Xklp1 function(s) by monitoring spindle assembly and microtubule behavior under a range of Xklp1 concentrations in egg extracts. We found that in the absence of Xklp1, bipolar spindles form with a reduced efficiency and display abnormalities associated with an increased microtubule mass. Likewise, centrosomal asters assembled in Xklp1-depleted extract show an increased microtubule mass. Conversely, addition of recombinant Xklp1 to the extract reduces the microtubule mass associated with spindles and...
37.
Hsp90 Regulates Activation of Interferon Regulatory Factor 3 and TBK-1 Stabilization in Sendai Virus-infected Cells - Yang, Kai; Shi, Hexin; Qi, Rong; Sun, Shaogang; Tang, Yujie; Zhang, Bianhong; Wang, Chen
Interferon regulatory factor 3 (IRF3) plays a crucial role in mediating cellular responses to virus intrusion. The protein kinase TBK1 is a key regulator inducing phosphorylation of IRF3. The regulatory mechanisms during IRF3 activation remain poorly characterized. In the present study, we have identified by yeast two-hybrid approach a specific interaction between IRF3 and chaperone heat-shock protein of 90 kDa (Hsp90). The C-terminal truncation mutant of Hsp90 is a strong dominant-negative inhibitor of IRF3 activation. Knockdown of endogenous Hsp90 by RNA interference attenuates IRF3 activation and its target gene expressions. Alternatively, Hsp90-specific inhibitor geldanamycin (GA) dramatically reduces expression of IRF3-regulated...
38.
Rck2 Is Required for Reprogramming of Ribosomes during Oxidative StressD? - Swaminathan, Swarna; Masek, Tomas; Molin, Claes; Pospisek, Martin; Sunnerhagen, Per
Rck2 is a mitogen-activated protein kinase-activated protein kinase in yeast implicated in translational regulation. rck2? mutants are mildly sensitive to oxidative stress, a condition that causes dissociation of actively translating ribosomes (polysomes). In rck2? cells, polysomes are lost to an even higher degree than in the wild-type upon stress. Cells overexpressing the catalytically inactive rck2-kd allele are highly sensitive to oxidative stress. In such cells, dissociation of polysomes upon stress was instead greatly delayed. The protein synthesis rate decreased to a similar degree as in wild-type cells, however, indicating that in rck2-kd cells, the polysome complexes were inactive. Array analyses...
39.
Survivin Modulates Microtubule Dynamics and Nucleation throughout the Cell CycleD?V? - Rosa, Jack; Canovas, Pedro; Islam, Ashraful; Altieri, Dario C.; Doxsey, Stephen J.
Survivin is a member of the chromosomal passenger complex implicated in kinetochore attachment, bipolar spindle formation, and cytokinesis. However, the mechanism by which survivin modulates these processes is unknown. Here, we show by time-lapse imaging of cells expressing either green fluorescent protein (GFP)-?-tubulin or the microtubule plus-end binding protein GFP-EB1 that depletion of survivin by small interfering RNAs (siRNAs) increased both the number of microtubules nucleated by centrosomes and the incidence of microtubule catastrophe, the transition from microtubule growth to shrinking. In contrast, survivin overexpression reduced centrosomal microtubule nucleation and suppressed both microtubule dynamics in mitotic spindles and bidirectional growth...
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