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Intracellular Transport (intracellular + transport)
Selected AbstractsManipulation of Individual Carbon Nanotubes by Reconstructing the Intracellular Transport of a Living CellADVANCED MATERIALS, Issue 10-11 2009Cerasela Zoica Dinu We used kinesin motor protein and its microtubule track to transport multi-walled carbon nanotubes (MWNTs) on engineered surfaces. Using a flow chamber, surface-adsorbed kinesins are shown to transport red-labeled microtubules loaded with green cargos of MWNTs. Our results establish a platform for assembling individually addressable MWNT nanostructures using microtubule templates. [source] Drosophila melanogaster p24 genes have developmental, tissue-specific, and sex-specific expression patterns and functionsDEVELOPMENTAL DYNAMICS, Issue 2 2007Kara A. Boltz Abstract Genes encoding members of the p24 family of intracellular trafficking proteins are present throughout animal and plant lineages. However, very little is known about p24 developmental, spatial, or sex-specific expression patterns or how localized expression affects function. We investigated these problems in Drosophila melanogaster, which contains nine genes encoding p24 proteins. One of these genes, logjam (loj), is expressed in the adult female nervous system and ovaries and is essential for oviposition. Nervous system-specific expression of loj, but not ovary-specific expression, rescues the behavioral defect of mutants. The Loj protein localizes to punctate structures in the cellular cytoplasm. These structures colocalize with a marker specific to the intermediate compartment and cis -Golgi, consistent with experimental evidence from other systems suggesting that p24 proteins function in intracellular transport between the endoplasmic reticulum and Golgi. Our findings reveal that Drosophila p24 transcripts are developmentally and tissue-specifically expressed. CG31787 is male-specifically expressed gene that is present during the larval, pupal, and adult stages. Female CG9053 mRNA is limited to the head, whereas males express this gene widely. Together, our studies provide experimental evidence indicating that some p24 genes have sex-specific expression patterns and tissue- and sex-limited functions. Developmental Dynamics 236:544,555, 2007. © 2006 Wiley-Liss, Inc. [source] The skin as a mirror of the ageing process in the human organism , results of the ageing research in the German National Genome Research Network 2EXPERIMENTAL DERMATOLOGY, Issue 8 2006CH. C. Zouboulis Intrinsic human skin ageing is influenced by the individual genetic predisposition and reflects degradation processes of the body. Hormones are decisively involved in intrinsic ageing with reduced secretion of pituitary, adrenal glands, and gonads, which leads to characteristic body and skin phenotypes. A number of advances were recently made in understanding skin ageing mechanisms and major molecular changes, especiallly of the extracellular matrix, were identified. Gene expression patterns compatible with mitotic misregulation and alterations in intracellular transport and metabolism were identified in fibroblasts of ageing humans and humans with progeria. Age-associated changes of extracellular matrix of the skin correlate well with changes been detected in the extracellular matrix of other organs of the human body. Within the National Genome Research Network 2 (NGFN-2) in Germany, the explorative project ,Genetic etiology of human longevity' targets the identification of age-related molecular pathways. For this purpose, skin models of ageing are used. Expression profiling employing cDNA microarrays from known and novel genes and RT-PCR are employed for gene detection and confirmation. Among the potential candidate genes several interesting target genes have been identified. The evaluation of ageing-associated genes in skin models will facilitate the understanding of global molecular ageing mechanisms in the future. [source] Impaired efflux of cholesterol from aged cells and its molecular mechanism: A basis for age-related enhancement of atherosclerosisGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 3 2007Shizuya Yamashita Aging is one of the risk factors for atherosclerotic cardiovascular diseases, however, its molecular mechanism is currently unknown. Many types of cells in the atherosclerotic lesions are considered to have various biological abnormalities such as impaired lipid homeostasis and slow cell proliferation, which may be related to senescence at cellular levels. One of the common characteristics of senescent cells in vitro is the alteration of actin cytoskeletons, which were reported to be involved in the intracellular transport of lipids. Cholesterol efflux from the cells is the initial step of reverse cholesterol transport, a major protective system against atherosclerosis. Recently, we demonstrated that Cdc42, a member of the Rho -GTPase family, might be crucial for cellular lipid transport and cholesterol efflux based upon studies of Tangier cells that are deficient in ABCA1 gene. In the current review, we also indicate that the expression of Cdc42 is decreased in the cells from aged subjects in close association with the retarded intracellular lipid transport. Furthermore, the Cdc42 expression is reduced by culturing fibroblasts in vitro for a long duration. Werner syndrome (WS) is characterized by the early onset of senescent phenotypes including premature atherosclerotic cardiovascular diseases, although the underlying molecular mechanism for the enhanced atherosclerosis has not been fully understood yet. We examined the intracellular lipid transport and cholesterol efflux and the expression levels of cholesterol efflux-related molecules in skin fibroblasts obtained from patients with WS. Cholesterol efflux was markedly reduced in the WS fibroblasts in association with an increased cellular cholesterol content. Fluorescent recovery after photobleaching technique revealed that intracellular lipid transport around Golgi apparatus was markedly reduced when using a C6-NBD-ceramide as a tracer. Cdc42 protein and its guanosine 5,-triphosphate-bound active form were markedly reduced in the WS fibroblasts. The adenovirus-mediated complementation of wild-type Cdc42 corrected the impaired cholesterol efflux, intracellular lipid transport and cellular cholesterol levels in the WS fibroblasts. These data indicate that the reduced expression of Cdc42 might be responsible for the abnormal lipid transport, which in turn might be related to the accelerated cardiovascular manifestations in WS patients. The current review focuses on the impaired efflux of cholesterol from aged cells and its molecular mechanism as a basis for age-related enhancement of atherosclerosis. [source] Insect glutathione transferases and insecticide resistanceINSECT MOLECULAR BIOLOGY, Issue 1 2005A. A. Enayati Abstract Glutathione transferases (GSTs) are a diverse family of enzymes found ubiquitously in aerobic organisms. They play a central role in the detoxification of both endogenous and xenobiotic compounds and are also involved in intracellular transport, biosynthesis of hormones and protection against oxidative stress. Interest in insect GSTs has primarily focused on their role in insecticide resistance. GSTs can metabolize insecticides by facilitating their reductive dehydrochlorination or by conjugation reactions with reduced glutathione, to produce water-soluble metabolites that are more readily excreted. In addition, they contribute to the removal of toxic oxygen free radical species produced through the action of pesticides. Annotation of the Anopheles gambiae and Drosophila melanogaster genomes has revealed the full extent of this enzyme family in insects. This mini review describes the insect GST enzyme family, focusing specifically on their role in conferring insecticide resistance. [source] Critical contact residues that mediate polymerization of nematode major sperm proteinJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2008Antonio del Castillo-Olivares Abstract The polymerization of protein filaments provides the motive force in a variety of cellular processes involving cell motility and intracellular transport. Regulated assembly and disassembly of the major sperm protein (MSP) underlies amoeboid movement in nematode sperm, and offers an attractive model system for characterizing the biomechanical properties of filament formation and force generation. To that end, structure-function studies of MSP from the nematode Caenorhabditis elegans have been performed. Recombinant MSP was purified from Escherichia coli using a novel affinity chromatography technique, and filament assembly was assessed by in vitro polymerization in the presence of polyethylene glycol. Prior molecular studies and structure from X-ray crystallography have implicated specific residues in protein,protein interactions necessary for filament assembly. Purified MSP containing substitutions in these residues fails to form filaments in vitro. Short peptides based on predicted sites of interaction also effectively disrupt MSP polymerization. These results confirm the structural determination of intermolecular contacts and demonstrate the importance of these residues in MSP assembly. J. Cell. Biochem. 104: 477,487, 2008. © 2007 Wiley-Liss, Inc. [source] Melanophores: A model system for neuronal transport and exocytosis?JOURNAL OF NEUROSCIENCE RESEARCH, Issue 12 2007Sara Aspengren Abstract Black pigment cells, melanophores, from lower vertebrates are specialized in bidirectional and coordinated translocation of pigment granules, melanosomes, in the cytoplasm. Melanophores develop from the neuronal crest and are most abundant in the dermal and epidermal layers of the skin, where the intracellular distribution of the pigment significantly influences the color of the animal. The transport of pigment is dependent on an intact cytoskeleton and motor proteins associated with cytoskeletal components. The easily cultured melanophores have proved to be excellent models for organelle transport because the intracellular movements of pigment can be visualized via light microscopy, and the granules move in response to defined chemical signals. The ease of achieving a combination of morphological and functional transport studies is the advantage of the melanophore system, and studies on pigment cells have revealed new components of the transport machinery, including molecular motors, their adapters, and transfer of vesicles to other cells. Many cellular components are transported with a combination of the actin- and microtubule-based transport systems, and, since all eukaryotic organisms rely on functional intracellular transport and an intact cytoskeleton, studies on melanophores are important for many aspects of cell biology, including axonal transport. In this review, we present an overview of the research on the pigment transport system and the potential use of pigment cells as a model system. © 2006 Wiley-Liss, Inc. [source] Characterization of ,-tubulin gene distinctively presented in a cytoplasmic male sterile and its maintainer line of non-heading Chinese cabbageJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2009Jingyi Zhang Abstract BACKGROUND: Microtubules are prominent components of the cytoskeleton in every eukaryotic cell. Plant microtubules are essential for a wide variety of cellular functions, including generation of cell polarity, intracellular transport, positioning of organelles, cell wall deposition and cell division. The major component of microtubules is tubulin, an ,,, heterodimer protein with a molecular mass of each subunit of around 50 kDa. Tubulin exists in cells as a mixture of polypeptides differing in their isoelectric points. Some post-translational modifications of tubulins are thought to modulate the functions and localization of microtubules within the cell. RESULTS: The complete sequence of a single-copy ,-tubulin gene Tuba1, belonging to a multiple gene family of non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino), was obtained. The gene was expressed in high levels in young leaves and stamens, and it was also highly expressed during all stages of microsporogenesis in the maintainer. However, there was a distinct difference in ,-tubulin expression between the sterile stage and the normal stages of pollen in a cytoplasmic male sterility line and its maintainer. CONCLUSION:Tuba1 was significantly related to the cell division and elongation of non-heading Chinese cabbage, demonstrating that this gene played an important role in the development of pollen and may be closely related to male sterility. Copyright © 2008 Society of Chemical Industry [source] Fluorescent protein fusions to a human immunodeficiency virus monoclonal antibody reveal its intracellular transport through the plant endomembrane systemPLANT BIOTECHNOLOGY JOURNAL, Issue 7 2008Sarah L. Irons Summary In order to further understand the production and intracellular trafficking of pharmaceutical proteins in plants, the light and heavy chains (LC and HC) of the human immunodeficiency virus neutralizing monoclonal antibody 2G12 were fused to fluorescent proteins [Venus and monomeric red fluorescent protein (mRFP)] to enable the visualization of their passage through the plant cell. Co-expression of LC and HC with various markers of the endomembrane system demonstrated that LC fusions were found in mobile punctate structures, which are likely to be pre-vacuolar compartments (PVCs) as a proportion of the LC fusions were found to be located in the vacuole. In addition, apoplast labelling was also observed with a 2G12LC-RFP fusion. The HC fusion expressed alone was found only in the endoplasmic reticulum (ER). When the LC and HC fusions were expressed together, they were found to co-locate to larger punctate structures, which were morphologically distinct from any observed on expression of LC or HC alone. These structures appeared to be in close association with the ER and their labelling partially overlapped with PVC marker fluorescence, but no increase in apoplast labelling was observed. Co-immunoprecipitation data demonstrated that the presence of the fluorescent proteins did not affect the assembly of the antibody, and also showed the association of BiP with the antibody chains. The antigen-binding activity of the Venus-fused 2G12 antibody was confirmed by enzyme-linked immunosorbent assay. [source] Hydrodynamics-based procedure involves transient hyperpermeability in the hepatic cellular membrane: implication of a nonspecific process in efficient intracellular gene deliveryTHE JOURNAL OF GENE MEDICINE, Issue 5 2004Naoki Kobayashi Abstract Background The mechanisms underlying the efficient gene transfer by a large-volume and high-speed intravenous injection of naked plasmid DNA (pDNA), a so-called hydrodynamics-based procedure, remain unclear and require further investigation. In this report, we have investigated possible mechanisms for the intracellular transport of naked pDNA by this procedure. Methods Propidium iodide (PI), a fluorescent indicator for cell membrane integrity, and luciferase- or green fluorescent protein (GFP)-expressing pDNA were injected into mice by the hydrodynamics-based procedure. Results PI was efficiently taken up by hepatocytes which appeared to be viable following the hydrodynamics-based procedure. Pre-expressed GFP in the cytosol was rapidly eliminated from the hepatocytes by a large-volume injection of saline. The profiles of plasma ALT and AST showed a steady decline with the highest values observed immediately after the hydrodynamics-based procedure. These results suggest that the hydrodynamics-based procedure produces a transient increase in the permeability of the cell membrane. The cellular uptake process appeared nonspecific, since simultaneous injection of an excess of empty vector did not affect the transgene expression. Sequential injections of a large volume of pDNA-free saline followed by naked pDNA in a normal volume revealed that the increase in membrane permeability was transient, with a return to normal conditions within 30 min. Transgene expression was observed in hepatocyte cultures isolated 10 min after pDNA delivery and in the liver as early as 10 min after luciferase-expressing RNA delivery, indicating that pDNA delivered immediately by the hydrodynamics-based procedure has the potential to produce successful transgene expression. Conclusions These findings suggest that the mechanism for the hydrodynamics-based gene transfer would involve in part the direct cytosolic delivery of pDNA through the cell membrane due to transiently increased permeability. Copyright © 2004 John Wiley & Sons, Ltd. [source] A hierarchical analysis of transcriptome alterations in intrauterine growth restriction (IUGR) reveals common pathophysiological pathways in mammals,THE JOURNAL OF PATHOLOGY, Issue 3 2007C Buffat Abstract Intra-uterine growth restriction (IUGR) is a frequent disease, affecting up to 10% of human pregnancies and responsible for increased perinatal morbidity and mortality. Moreover, low birth weight is an important cause of the metabolic syndrome in the adult. Protein depletion during the gestation of rat females has been widely used as a model for human IUGR. By transcriptome analysis of control and protein-deprived rat placentas, we were able to identify 2543 transcripts modified more than 2.5 fold (1347 induced and 1196 repressed). Automatic functional classification enabled us to identify clusters of induced genes affecting chromosome structure, transcription, intracellular transport, protein modifications and apoptosis. In particular, we suggest the existence of a complex balance regulating apoptosis. Among repressed genes, we noted several groups of genes involved in immunity, signalling and degradation of noxious chemicals. These observations suggest that IUGR placentas have a decreased resistance to external aggression. The promoters of the most induced and most repressed genes were contrasted for their composition in putative transcription factor binding sites. There was an over-representation of Znfinger (ZNF) proteins and Pdx1 (pancreatic and duodenal homeobox protein 1) putative binding sites. Consistently, Pdx1 and a high proportion of ZNF genes were induced at the transcriptional level. A similar analysis of ZNF promoters showed an increased presence of putative binding sites for the Tata box binding protein (Tbp). Consistently again, we showed that the Tbp and TBP-associated factors (Tafs) were up-regulated in IUGR placentas. Also, samples of human IUGR and control placentas showed that human orthologous ZNFs and PDX1 were transcriptionnally induced, especially in non-vascular IUGR. Immunohistochemistry revealed increased expression of PDX1 in IUGR human placentas. In conclusion, our approach permitted the proposition of hypotheses on a hierarchy of gene inductions/repressions leading to massive transcriptional alterations in the IUGR placenta, in humans and in rodents. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Ecdysteroid receptor (EcR) is associated with microtubules and with mitochondria in the cytoplasm of prothoracic gland cells of Rhodnius prolixus (Hemiptera)ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 4 2009Xanthe Vafopoulou Abstract We have shown previously that EcR in larval Rhodnius is present in the cytoplasm of various cell types and undergoes daily cycling in abundance in the cytoplasm (Vafopoulou and Steel, 2006. Cell Tissue Res 323:443,455). It is unknown which organelles are associated with EcR. Here, we report that cytoplasmic EcR in prothoracic gland cells is associated with both microtubules and mitochondria, and discuss the implications for both nuclear and non-genomic actions of EcR. EcR was localized immunohistochemically using several antibodies to EcR of Manduca and Drosophila and a confocal laser scanning microscope. Double labels were made to visualize EcR and (1) microtubules (using an antibody to tyrosylated ,-tubulin) and (2) mitochondria (using a fluorescent MitoTracker probe), both after stabilization of microtubules with taxol. EcR co-localized with both tubulin and mitochondria. All the different EcR antibodies produced similar co-localization patterns. EcR was seen in the perinuclear aggregation of mitochondria, indicating that mitochondria are targets of ecdysone, which could influence mitochondrial gene transcription. EcR was also distributed throughout the microtubule network. Co-localization of EcR with tubulin or mitochondria was maintained after depolymerization of microtubules with colchicine. Treatment with taxol resulted in accumulation of EcR in the cytoplasm and simultaneous depletion of EcR from the nucleus, suggesting that microtubules may be involved in targeted intracellular transport of EcR to the nucleus (genomic action) or may play a role in rapid ecdysone signal transduction in the extranuclear compartment, i.e., in non-genomic actions of ecdysone. These findings align EcR more closely with steroid hormone receptors in vertebrates. © 2009 Wiley Periodicals, Inc. [source] Crystallization and preliminary X-ray crystallographic analysis of BxlA, an intracellular ,- d -xylosidase from Streptomyces thermoviolaceus OPC-520ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 7 2010Hideaki Morioka BxlA from Streptomyces thermoviolaceus OPC-520, together with the extracellular BxlE and the integral membrane proteins BxlF and BxlG, constitutes a xylanolytic system that participates in the intracellular transport of xylan-degradation products and the production of xylose. To elucidate the mechanism of the hydrolytic degradation of xylooligosaccharides to xylose at the atomic level, X-ray structural analysis of BxlA was attempted. The recombinant BxlA protein (molecular weight 82,kDa) was crystallized by the hanging-drop vapour-diffusion method at 289,K. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 142.2, b = 129.5, c = 101.4,Å, , = 119.8°, and contained two molecules per asymmetric unit (VM = 2.47,Å3,Da,1). Diffraction data were collected to a resolution to 2.50,Å and provided a data set with an overall Rmerge of 8.3%. [source] A case of purpura fulminans is caused by homozygous ,8857 mutation (protein C-Nagoya) and successfully treated with activated protein C concentrateBRITISH JOURNAL OF HAEMATOLOGY, Issue 3 2000Takayuki Nakayama We report a Japanese patient who developed purpura fulminans and disseminated intravascular coagulation (DIC) shortly after birth. The patient was diagnosed to be homozygous for protein C deficiency and was treated with an activated protein C (APC) concentrate. Intravenous infusions of APC markedly improved the necrotic skin lesions and the anticoagulation by APC enabled successful DIC control. The identified mutation (,8857) results in impaired intracellular transport and protein maturation and would be the cause of the complete protein C deficiency. This is the seventh case of the mutation that has been exclusively reported in Japan, but is the first report of a homozygous case. Our findings propose new therapeutic and diagnostic tools for the management of this fatal thrombotic disease. [source] An insider's guide to the microtubule cytoskeleton of GiardiaCELLULAR MICROBIOLOGY, Issue 5 2010Scott C. Dawson Summary Giardia intestinalis is a zoonotic, parasitic protist with a complex microtubule cytoskeleton critical for motility, attachment, intracellular transport, cell division and transitioning between its two life cycle stages , the cyst and the trophozoite. This review focuses on the structures of the primary elements of the microtubule cytoskeleton and cytoskeletal dynamics throughout this complex giardial life cycle. The giardial cytoskeleton has both highly dynamic elements and more stable MT structures, including several novel structures like the ventral disc that change conformation via unknown mechanisms. While our knowledge of the giardial cytoskeleton is primarily cytological, the completed Giardia genome and recently developed reverse genetic tools affords an opportunity to uncover the mechanisms of Giardia's cytoskeletal dynamics. Fundamental areas of giardial cytoskeletal biology remain to be explored, including high resolution imaging and compositional characterization of cytoskeletal structures required for elucidating the molecular mechanisms of cytoskeletal functioning. [source] Molecular motors hijacking by intracellular pathogensCELLULAR MICROBIOLOGY, Issue 1 2006Thomas Henry Summary Cargoes are transported intracellularly along cytoskeletal tracks composed of actin or tubulin. Their movement involves the action of molecular motor proteins that generate directed movement along microtubules or actin filaments. The three classes of molecular motors , kinesins, dyneins and myosins , are involved in a multiplicity of biological movements such as mitosis, positioning of organelles, intracellular transports and also vesicular sorting through membrane tubulation and fission and delivery to their target compartment. Intracellular pathogens use this molecular machinery to reach their site of replication, to leave their host or to control the dynamics of membrane exchanges with their replication compartment. [source] | ||||||||||||||||