Isolation of the Lateral Border Recycling Compartment using a diaminobenzidine-induced density shift

PubMed Central

Sullivan, David P.; Rüffer, Claas; Muller, William A.

2014-01-01

The migration of leukocytes across the endothelium and into tissue is critical to mounting an inflammatory response. The Lateral Border Recycling Compartment (LBRC), a complex vesicular-tubule invagination of the plasma membrane found at endothelial cell borders, plays an important role in the this process. Although a few proteins have been shown to be present in the LBRC, no unique marker is known. Here we detail methods that can be used to characterize a subcellular compartment that lacks an identifying marker. Initial characterization of the LBRC was performed using standard subcellular fractionation with sucrose gradients and took advantage of the observation that the compartment migrated at a lower density than other membrane compartments. To isolate larger quantities of the compartment, we modified a classic technique known as a diaminobenzidine (DAB)-induced density shift. The DAB-induced density shift allowed for specific isolation of membranes labeled with HRP conjugated antibody. Because the LBRC could be differentially labeled at 4°C and 37°C, we were able to identify proteins that are enriched in the compartment, despite lacking a unique marker. These methods serve as a model to others studying poorly characterized compartments and organelles and are applicable to a wide variety of biological systems. PMID:24915828

Quantitative Analysis of Subcellular Distribution of the SUMO Conjugation System by Confocal Microscopy Imaging.

PubMed

Mas, Abraham; Amenós, Montse; Lois, L Maria

2016-01-01

Different studies point to an enrichment in SUMO conjugation in the cell nucleus, although non-nuclear SUMO targets also exist. In general, the study of subcellular localization of proteins is essential for understanding their function within a cell. Fluorescence microscopy is a powerful tool for studying subcellular protein partitioning in living cells, since fluorescent proteins can be fused to proteins of interest to determine their localization. Subcellular distribution of proteins can be influenced by binding to other biomolecules and by posttranslational modifications. Sometimes these changes affect only a portion of the protein pool or have a partial effect, and a quantitative evaluation of fluorescence images is required to identify protein redistribution among subcellular compartments. In order to obtain accurate data about the relative subcellular distribution of SUMO conjugation machinery members, and to identify the molecular determinants involved in their localization, we have applied quantitative confocal microscopy imaging. In this chapter, we will describe the fluorescent protein fusions used in these experiments, and how to measure, evaluate, and compare average fluorescence intensities in cellular compartments by image-based analysis. We show the distribution of some components of the Arabidopsis SUMOylation machinery in epidermal onion cells and how they change their distribution in the presence of interacting partners or even when its activity is affected.

Biosensor reveals multiple sources for mitochondrial NAD⁺.

PubMed

Cambronne, Xiaolu A; Stewart, Melissa L; Kim, DongHo; Jones-Brunette, Amber M; Morgan, Rory K; Farrens, David L; Cohen, Michael S; Goodman, Richard H

2016-06-17

Nicotinamide adenine dinucleotide (NAD(+)) is an essential substrate for sirtuins and poly(adenosine diphosphate-ribose) polymerases (PARPs), which are NAD(+)-consuming enzymes localized in the nucleus, cytosol, and mitochondria. Fluctuations in NAD(+) concentrations within these subcellular compartments are thought to regulate the activity of NAD(+)-consuming enzymes; however, the challenge in measuring compartmentalized NAD(+) in cells has precluded direct evidence for this type of regulation. We describe the development of a genetically encoded fluorescent biosensor for directly monitoring free NAD(+) concentrations in subcellular compartments. We found that the concentrations of free NAD(+) in the nucleus, cytoplasm, and mitochondria approximate the Michaelis constants for sirtuins and PARPs in their respective compartments. Systematic depletion of enzymes that catalyze the final step of NAD(+) biosynthesis revealed cell-specific mechanisms for maintaining mitochondrial NAD(+) concentrations. Copyright © 2016, American Association for the Advancement of Science.

The sub-cellular fate of mercury in the liver of wild mullets (Liza aurata)--Contribution to the understanding of metal-induced cellular toxicity.

PubMed

Araújo, Olinda; Pereira, Patrícia; Cesário, Rute; Pacheco, Mário; Raimundo, Joana

2015-06-15

Mercury is a recognized harmful pollutant in aquatic systems but still little is known about its sub-cellular partitioning in wild fish. Mercury concentrations in liver homogenate (whole organ load) and in six sub-cellular compartments were determined in wild Liza aurata from two areas - contaminated (LAR) and reference. Water and sediment contamination was also assessed. Fish from LAR displayed higher total mercury (tHg) organ load as well as in sub-cellular compartments than those from the reference area, reflecting environmental differences. However, spatial differences in percentage of tHg were only observed for mitochondria (Mit) and lysosomes plus microsomes (Lys+Mic). At LAR, Lys+Mic exhibited higher levels of tHg than the other fractions. Interestingly, tHg in Mit, granules (Gran) and heat-denaturable proteins was linearly correlated with the whole organ. Low tHg concentrations in heat stable proteins and Gran suggests that accumulated levels might be below the physiological threshold to activate those detoxification fractions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Rice proteome database: a step toward functional analysis of the rice genome.

PubMed

Komatsu, Setsuko

2005-09-01

The technique of proteome analysis using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) has the power to monitor global changes that occur in the protein complement of tissues and subcellular compartments. In this study, the proteins of rice were cataloged, a rice proteome database was constructed, and a functional characterization of some of the identified proteins was undertaken. Proteins extracted from various tissues and subcellular compartments in rice were separated by 2D-PAGE and an image analyzer was used to construct a display of the proteins. The Rice Proteome Database contains 23 reference maps based on 2D-PAGE of proteins from various rice tissues and subcellular compartments. These reference maps comprise 13129 identified proteins, and the amino acid sequences of 5092 proteins are entered in the database. Major proteins involved in growth or stress responses were identified using the proteome approach. Some of these proteins, including a beta-tubulin, calreticulin, and ribulose-1,5-bisphosphate carboxylase/oxygenase activase in rice, have unexpected functions. The information obtained from the Rice Proteome Database will aid in cloning the genes for and predicting the function of unknown proteins.

Subcellular Distribution of O-Acetylserine(thiol)lyase in Cauliflower (Brassica oleracea L.) Inflorescence.

PubMed

Rolland, N; Droux, M; Douce, R

1992-03-01

The subcellular localization of O-acetyiserine(thiol)lyase (EC 4.2.99.8) in nongreen tissue from higher plants has been studied using purified proplastids, mitochondria, and protoplasts from cauliflower (Brassica oleracea L.) buds as a source of subcellular fractions. O-Acetylserine(thiol)lyase has been detected in both organelles (proplastids and mitochondria) and a cytosolic extract obtained by protoplast fractionation. We confirmed these observations, demonstrating that a form of the enzyme different in global charge and separated from others by anion-exchange chromatography corresponded to each subcellular location. Our observations are consistent with the need for cysteine biosynthesis in each subcellular compartment where the synthesis of proteins occurs.

Subcellular Distribution of O-Acetylserine(thiol)lyase in Cauliflower (Brassica oleracea L.) Inflorescence

PubMed Central

Rolland, Norbert; Droux, Michel; Douce, Roland

1992-01-01

The subcellular localization of O-acetyiserine(thiol)lyase (EC 4.2.99.8) in nongreen tissue from higher plants has been studied using purified proplastids, mitochondria, and protoplasts from cauliflower (Brassica oleracea L.) buds as a source of subcellular fractions. O-Acetylserine(thiol)lyase has been detected in both organelles (proplastids and mitochondria) and a cytosolic extract obtained by protoplast fractionation. We confirmed these observations, demonstrating that a form of the enzyme different in global charge and separated from others by anion-exchange chromatography corresponded to each subcellular location. Our observations are consistent with the need for cysteine biosynthesis in each subcellular compartment where the synthesis of proteins occurs. ImagesFigure 1 PMID:16668766

FRET-based genetically-encoded sensors for quantitative monitoring of metabolites.

PubMed

Mohsin, Mohd; Ahmad, Altaf; Iqbal, Muhammad

2015-10-01

Neighboring cells in the same tissue can exist in different states of dynamic activities. After genomics, proteomics and metabolomics, fluxomics is now equally important for generating accurate quantitative information on the cellular and sub-cellular dynamics of ions and metabolite, which is critical for functional understanding of organisms. Various spectrometry techniques are used for monitoring ions and metabolites, although their temporal and spatial resolutions are limited. Discovery of the fluorescent proteins and their variants has revolutionized cell biology. Therefore, novel tools and methods targeting sub-cellular compartments need to be deployed in specific cells and targeted to sub-cellular compartments in order to quantify the target-molecule dynamics directly. We require tools that can measure cellular activities and protein dynamics with sub-cellular resolution. Biosensors based on fluorescence resonance energy transfer (FRET) are genetically encoded and hence can specifically target sub-cellular organelles by fusion to proteins or targetted sequences. Since last decade, FRET-based genetically encoded sensors for molecules involved in energy production, reactive oxygen species and secondary messengers have helped to unravel key aspects of cellular physiology. This review, describing the design and principles of sensors, presents a database of sensors for different analytes/processes, and illustrate examples of application in quantitative live cell imaging.

Subcellular Redox Signaling.

PubMed

Zhu, Liping; Lu, Yankai; Zhang, Jiwei; Hu, Qinghua

2017-01-01

Oxidative and antioxidative system of cells and tissues maintains a balanced state under physiological conditions. A disruption in this balance of redox status has been associated with numerous pathological processes. Reactive oxygen species (ROS) as a major redox signaling generates in a spatiotemporally dependent manner. Subcellular organelles such as mitochondria, endoplasmic reticulum, plasma membrane and nuclei contribute to the production of ROS. In addition to downstream effects of ROS signaling regulated by average ROS changes in cytoplasm, whether subcelluar ROS mediate biological effect(s) has drawn greater attentions. With the advance in redox-sensitive probes targeted to different subcellular compartments, the investigation of subcellular ROS signaling and its associated cellular function has become feasible. In this review, we discuss the subcellular ROS signaling, with particular focus on mechanisms of subcellular ROS production and its downstream effects.

Volatile science? Metabolic engineering of terpenoids in plants.

PubMed

Aharoni, Asaph; Jongsma, Maarten A; Bouwmeester, Harro J

2005-12-01

Terpenoids are important for plant survival and also possess biological properties that are beneficial to humans. Here, we describe the state of the art in terpenoid metabolic engineering, showing that significant progress has been made over the past few years. Subcellular targeting of enzymes has demonstrated that terpenoid precursors in subcellular compartments are not as strictly separated as previously thought and that multistep pathway engineering is feasible, even across cell compartments. These engineered plants show that insect behavior is influenced by terpenoids. In the future, we expect rapid progress in the engineering of terpenoid production in plants. In addition to commercial applications, such transgenic plants should increase our understanding of the biological relevance of these volatile secondary metabolites.

Quantitative imaging with fluorescent biosensors.

PubMed

Okumoto, Sakiko; Jones, Alexander; Frommer, Wolf B

2012-01-01

Molecular activities are highly dynamic and can occur locally in subcellular domains or compartments. Neighboring cells in the same tissue can exist in different states. Therefore, quantitative information on the cellular and subcellular dynamics of ions, signaling molecules, and metabolites is critical for functional understanding of organisms. Mass spectrometry is generally used for monitoring ions and metabolites; however, its temporal and spatial resolution are limited. Fluorescent proteins have revolutionized many areas of biology-e.g., fluorescent proteins can report on gene expression or protein localization in real time-yet promoter-based reporters are often slow to report physiologically relevant changes such as calcium oscillations. Therefore, novel tools are required that can be deployed in specific cells and targeted to subcellular compartments in order to quantify target molecule dynamics directly. We require tools that can measure enzyme activities, protein dynamics, and biophysical processes (e.g., membrane potential or molecular tension) with subcellular resolution. Today, we have an extensive suite of tools at our disposal to address these challenges, including translocation sensors, fluorescence-intensity sensors, and Förster resonance energy transfer sensors. This review summarizes sensor design principles, provides a database of sensors for more than 70 different analytes/processes, and gives examples of applications in quantitative live cell imaging.

Incoordination among Subcellular Compartments Is Associated with Depression-Like Behavior Induced by Chronic Mild Stress

PubMed Central

Xu, Aiping; Cui, Shan

2016-01-01

Background: Major depressive disorder is characterized as persistent low mood. A chronically stressful life in genetically susceptible individuals is presumably the major etiology that leads to dysfunctions of monoamine and hypothalamus-pituitary-adrenal axis. These pathogenic factors cause neuron atrophy in the limbic system for major depressive disorder. Cell-specific pathophysiology is unclear, so we investigated prelimbic cortical GABAergic neurons and their interaction with glutamatergic neurons in depression-like mice. Methods: Mice were treated with chronic unpredictable mild stress for 3 weeks until they expressed depression-like behaviors confirmed by sucrose preference, Y-maze, and forced swimming tests. The structures and functions of GABAergic and glutamatergic units in prelimbic cortices were studied by cell imaging and electrophysiology in chronic unpredictable mild stress-induced depression mice vs controls. Results: In depression-like mice, prelimbic cortical GABAergic neurons show incoordination among the subcellular compartments, such as decreased excitability and synaptic outputs as well as increased reception from excitatory inputs. GABAergic synapses on glutamatergic cells demonstrate decreased presynaptic innervation and increased postsynaptic responsiveness. Conclusions: Chronic unpredictable mild stress-induced incoordination in prelimbic cortical GABAergic and glutamatergic neurons dysregulates their target neurons, which may be the pathological basis for depressive mood. The rebalance of compatibility among subcellular compartments would be an ideal strategy to treat neural disorders. PMID:26506857

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rojas, Joselyn; Teran-Angel, Guillermo; Barbosa, Luisa

Foxp3 is considered to be the master regulator for the development and function of regulatory T cells (Treg). Recently Foxp3, has been detected in extra lymphoid tissue, and in hepatocytes and has been associated with hepatocellular carcinoma (HCC), although its role has not been defined. Since it is expected that there is a relationship between protein localization, activity and cellular function, the aim of this study was to explore the subcellular localization of Foxp3 in resting and stimulated human hepatocytes. Foxp3 expression was measured by flow cytometry, subcellular fractioning, and immunofluorescence, and this data was used to track the shuttlingmore » of Foxp3 in different subcellular compartments in hepatocytes (HepG2 cell line), stimulated by using the PKC activators (PMA), core and preS1/2 antigen from hepatitis B virus (HBV). Our data shows that besides the nuclear location, mitochondrial translocation was detected after stimulation with PMA and at to a lesser extent, with preS1/2. In addition, Foxp3 is localizes at outer mitochondrial membrane. These results suggest a non-canonical role of Foxp3 in the mitochondrial compartment in human hepatocytes, and opens a new field about their role in liver damages during HBV infection. - Highlights: • The expression and subcellular distribution of Foxp3, is modulated by PMA and preS1/2. • PMA and preS1/2 increase Foxp3 expression on HepG2. • PMA and preS1/2 induce foxp3 enrichment at mitochondrial, microsomal and nuclear compartments. • Results suggest a non-canonical function of Foxp3 or a mitochondrial transcriptional activity.« less

Immunogold labeling reveals subcellular localisation of silica nanoparticles in a human blood-brain barrier model

NASA Astrophysics Data System (ADS)

Ye, Dong; Anguissola, Sergio; O'Neill, Tiina; Dawson, Kenneth A.

2015-05-01

Subcellular location of nanoparticles has been widely investigated with fluorescence microscopy, via fluorescently labeled antibodies to visualise target antigens in cells. However, fluorescence microscopy, such as confocal or live cell imaging, has generally limited 3D spatial resolution. Conventional electron microscopy can be useful in bridging resolution gap, but still not ideal in resolving subcellular organelle identities. Using the pre-embedding immunogold electron microscopic imaging, we performed accurate examination of the intracellular trafficking and gathered further evidence of transport mechanisms of silica nanoparticles across a human in vitro blood-brain barrier model. Our approach can effectively immunolocalise a variety of intracellular compartments and provide new insights into the uptake and subcellular transport of nanoparticles.Subcellular location of nanoparticles has been widely investigated with fluorescence microscopy, via fluorescently labeled antibodies to visualise target antigens in cells. However, fluorescence microscopy, such as confocal or live cell imaging, has generally limited 3D spatial resolution. Conventional electron microscopy can be useful in bridging resolution gap, but still not ideal in resolving subcellular organelle identities. Using the pre-embedding immunogold electron microscopic imaging, we performed accurate examination of the intracellular trafficking and gathered further evidence of transport mechanisms of silica nanoparticles across a human in vitro blood-brain barrier model. Our approach can effectively immunolocalise a variety of intracellular compartments and provide new insights into the uptake and subcellular transport of nanoparticles. Electronic supplementary information (ESI) available: Nanoparticle characterisation data, preservation of cellular structures, staining controls, optimisation of size amplification via the silver enhancement, and more imaging results from anti-clathrin and anti-caveolin 1 immunolabeling. See DOI: 10.1039/c5nr01539a

Extending roGFP Emission via Förster-Type Resonance Energy Transfer Relay Enables Simultaneous Dual Compartment Ratiometric Redox Imaging in Live Cells.

PubMed

Norcross, Stevie; Trull, Keelan J; Snaider, Jordan; Doan, Sara; Tat, Kiet; Huang, Libai; Tantama, Mathew

2017-11-22

Reactive oxygen species (ROS) mediate both intercellular and intraorganellar signaling, and ROS propagate oxidative stress between cellular compartments such as mitochondria and the cytosol. Each cellular compartment contains its own sources of ROS as well as antioxidant mechanisms, which contribute to dynamic fluctuations in ROS levels that occur during signaling, metabolism, and stress. However, the coupling of redox dynamics between cellular compartments has not been well studied because of the lack of available sensors to simultaneously measure more than one subcellular compartment in the same cell. Currently, the redox-sensitive green fluorescent protein, roGFP, has been used extensively to study compartment-specific redox dynamics because it provides a quantitative ratiometric readout and it is amenable to subcellular targeting as a genetically encoded sensor. Here, we report a new family of genetically encoded fluorescent protein sensors that extend the fluorescence emission of roGFP via Förster-type resonance energy transfer to an acceptor red fluorescent protein for dual-color live-cell microscopy. We characterize the redox and optical properties of the sensor proteins, and we demonstrate that they can be used to simultaneously measure cytosolic and mitochondrial ROS in living cells. Furthermore, we use these sensors to reveal cell-to-cell heterogeneity in redox coupling between the cytosol and mitochondria when neuroblastoma cells are exposed to reductive and metabolic stresses.

Geometric approach to segmentation and protein localization in cell culture assays.

PubMed

Raman, S; Maxwell, C A; Barcellos-Hoff, M H; Parvin, B

2007-01-01

Cell-based fluorescence imaging assays are heterogeneous and require the collection of a large number of images for detailed quantitative analysis. Complexities arise as a result of variation in spatial nonuniformity, shape, overlapping compartments and scale (size). A new technique and methodology has been developed and tested for delineating subcellular morphology and partitioning overlapping compartments at multiple scales. This system is packaged as an integrated software platform for quantifying images that are obtained through fluorescence microscopy. Proposed methods are model based, leveraging geometric shape properties of subcellular compartments and corresponding protein localization. From the morphological perspective, convexity constraint is imposed to delineate and partition nuclear compartments. From the protein localization perspective, radial symmetry is imposed to localize punctate protein events at submicron resolution. Convexity constraint is imposed against boundary information, which are extracted through a combination of zero-crossing and gradient operator. If the convexity constraint fails for the boundary then positive curvature maxima are localized along the contour and the entire blob is partitioned into disjointed convex objects representing individual nuclear compartment, by enforcing geometric constraints. Nuclear compartments provide the context for protein localization, which may be diffuse or punctate. Punctate signal are localized through iterative voting and radial symmetries for improved reliability and robustness. The technique has been tested against 196 images that were generated to study centrosome abnormalities. Corresponding computed representations are compared against manual counts for validation.

Subcellular storage compartments of bacteriopheophorbide sensitizers

NASA Astrophysics Data System (ADS)

Moser, Joerg G.; Dembeck, U.; Hubert, M.; Spengler, Bernhard; Bayer, Rainer; Wagner, Birgit

1994-03-01

Fluorescence colocalization with the Golgi specific stain, NBD-ceramide, and the mitochondrial localizing stain, Rhodamine 123, confirmed the earlier assumption that the Golgi apparatus is one of the prominent storage compartments for bacteriopheophorbide esters in OAT 75 SCLC cells and several amelanotic melanoma cell lines (A375, Melur SP18, SkAMel 25). Furthermore, a diffuse staining of mitochondria, of non-structured cytoplasm, and an additional storage in melanine vesicles of the amelanotic melanoma cells suggests further storage compartments with quantitatively different contributions to the phototoxicity of bacteriochlorophyll-derived photosensitizers. Independent observations of early phototoxic effects on microfilamentous networks, enzymatic activities (succinate dehydrogenase, lactate dehydrogenase), and redistribution phenomena following primary uptake of the sensitizers let us assume that only a part of the 108 molecules taken up by a cell contribute directly to phototoxicity. Thus it may be asked if a proper subcellular positioning of only a few sensitizer molecules may have similar phototoxic effects as the huge amounts stored at apparently ineffective sites.

Subcellular targeting and interactions among the Potato virus X TGB proteins.

PubMed

Samuels, Timmy D; Ju, Ho-Jong; Ye, Chang-Ming; Motes, Christy M; Blancaflor, Elison B; Verchot-Lubicz, Jeanmarie

2007-10-25

Potato virus X (PVX) encodes three proteins named TGBp1, TGBp2, and TGBp3 which are required for virus cell-to-cell movement. To determine whether PVX TGB proteins interact during virus cell-cell movement, GFP was fused to each TGB coding sequence within the viral genome. Confocal microscopy was used to study subcellular accumulation of each protein in virus-infected plants and protoplasts. GFP:TGBp2 and TGBp3:GFP were both seen in the ER, ER-associated granular vesicles, and perinuclear X-bodies suggesting that these proteins interact in the same subdomains of the endomembrane network. When plasmids expressing CFP:TGBp2 and TGBp3:GFP were co-delivered to tobacco leaf epidermal cells, the fluorescent signals overlapped in ER-associated granular vesicles indicating that these proteins colocalize in this subcellular compartment. GFP:TGBp1 was seen in the nucleus, cytoplasm, rod-like inclusion bodies, and in punctate sites embedded in the cell wall. The puncta were reminiscent of previous reports showing viral proteins in plasmodesmata. Experiments using CFP:TGBp1 and YFP:TGBp2 or TGBp3:GFP showed CFP:TGBp1 remained in the cytoplasm surrounding the endomembrane network. There was no evidence that the granular vesicles contained TGBp1. Yeast two hybrid experiments showed TGBp1 self associates but failed to detect interactions between TGBp1 and TGBp2 or TGBp3. These experiments indicate that the PVX TGB proteins have complex subcellular accumulation patterns and likely cooperate across subcellular compartments to promote virus infection.

Subcellular distribution of raffinose oligosaccharides and other metabolites in summer and winter leaves of Ajuga reptans (Lamiaceae).

PubMed

Findling, Sarah; Zanger, Klaus; Krueger, Stephan; Lohaus, Gertrud

2015-01-01

In Ajuga reptans, raffinose oligosaccharides accumulated during winter. Stachyose, verbascose, and higher RFO oligomers were exclusively found in the vacuole whereas one-fourth of raffinose was localized in the stroma. The evergreen labiate Ajuga reptans L. can grow at low temperature. The carbohydrate metabolism changes during the cold phase, e.g., raffinose family oligosaccharides (RFOs) accumulate. Additionally, A. reptans translocates RFOs in the phloem. In the present study, subcellular concentrations of metabolites were studied in summer and winter leaves of A. reptans to gain further insight into regulatory instances involved in the cold acclimation process and into the function of RFOs. Subcellular metabolite concentrations were determined by non-aqueous fractionation. Volumes of the subcellular compartments of summer and winter leaves were analyzed by morphometric measurements. The metabolite content varied strongly between summer and winter leaves. Soluble metabolites increased up to tenfold during winter whereas the starch content was decreased. In winter leaves, the subcellular distribution showed a shift of carbohydrates from cytoplasm to vacuole and chloroplast. Despite this, the metabolite concentration was higher in all compartments in winter leaves compared to summer leaves because of the much higher total metabolite content in winter leaves. The different oligosaccharides did show different compartmentations. Stachyose, verbascose, and higher RFO oligomers were almost exclusively found in the vacuole whereas one-fourth of raffinose was localized in the stroma. Apparently, the subcellular distribution of the RFOs differs because they fulfill different functions in plant metabolism during winter. Raffinose might function in protecting chloroplast membranes during freezing, whereas higher RFO oligomers may exert protective effects on vacuolar membranes. In addition, the high content of RFOs in winter leaves may also result from reduced consumption of assimilates.

Estimating the magnitude of near-membrane PDE4 activity in living cells.

PubMed

Xin, Wenkuan; Feinstein, Wei P; Britain, Andrea L; Ochoa, Cristhiaan D; Zhu, Bing; Richter, Wito; Leavesley, Silas J; Rich, Thomas C

2015-09-15

Recent studies have demonstrated that functionally discrete pools of phosphodiesterase (PDE) activity regulate distinct cellular functions. While the importance of localized pools of enzyme activity has become apparent, few studies have estimated enzyme activity within discrete subcellular compartments. Here we present an approach to estimate near-membrane PDE activity. First, total PDE activity is measured using traditional PDE activity assays. Second, known cAMP concentrations are dialyzed into single cells and the spatial spread of cAMP is monitored using cyclic nucleotide-gated channels. Third, mathematical models are used to estimate the spatial distribution of PDE activity within cells. Using this three-tiered approach, we observed two pharmacologically distinct pools of PDE activity, a rolipram-sensitive pool and an 8-methoxymethyl IBMX (8MM-IBMX)-sensitive pool. We observed that the rolipram-sensitive PDE (PDE4) was primarily responsible for cAMP hydrolysis near the plasma membrane. Finally, we observed that PDE4 was capable of blunting cAMP levels near the plasma membrane even when 100 μM cAMP were introduced into the cell via a patch pipette. Two compartment models predict that PDE activity near the plasma membrane, near cyclic nucleotide-gated channels, was significantly lower than total cellular PDE activity and that a slow spatial spread of cAMP allowed PDE activity to effectively hydrolyze near-membrane cAMP. These results imply that cAMP levels near the plasma membrane are distinct from those in other subcellular compartments; PDE activity is not uniform within cells; and localized pools of AC and PDE activities are responsible for controlling cAMP levels within distinct subcellular compartments. Copyright © 2015 the American Physiological Society.

Estimating the magnitude of near-membrane PDE4 activity in living cells

PubMed Central

Xin, Wenkuan; Feinstein, Wei P.; Britain, Andrea L.; Ochoa, Cristhiaan D.; Zhu, Bing; Richter, Wito; Leavesley, Silas J.

2015-01-01

Recent studies have demonstrated that functionally discrete pools of phosphodiesterase (PDE) activity regulate distinct cellular functions. While the importance of localized pools of enzyme activity has become apparent, few studies have estimated enzyme activity within discrete subcellular compartments. Here we present an approach to estimate near-membrane PDE activity. First, total PDE activity is measured using traditional PDE activity assays. Second, known cAMP concentrations are dialyzed into single cells and the spatial spread of cAMP is monitored using cyclic nucleotide-gated channels. Third, mathematical models are used to estimate the spatial distribution of PDE activity within cells. Using this three-tiered approach, we observed two pharmacologically distinct pools of PDE activity, a rolipram-sensitive pool and an 8-methoxymethyl IBMX (8MM-IBMX)-sensitive pool. We observed that the rolipram-sensitive PDE (PDE4) was primarily responsible for cAMP hydrolysis near the plasma membrane. Finally, we observed that PDE4 was capable of blunting cAMP levels near the plasma membrane even when 100 μM cAMP were introduced into the cell via a patch pipette. Two compartment models predict that PDE activity near the plasma membrane, near cyclic nucleotide-gated channels, was significantly lower than total cellular PDE activity and that a slow spatial spread of cAMP allowed PDE activity to effectively hydrolyze near-membrane cAMP. These results imply that cAMP levels near the plasma membrane are distinct from those in other subcellular compartments; PDE activity is not uniform within cells; and localized pools of AC and PDE activities are responsible for controlling cAMP levels within distinct subcellular compartments. PMID:26201952

Tropomyosins as discriminators of myosin function.

PubMed

Ostap, E Michael

2008-01-01

Vertebrate nonmuscle cells express multiple tropomyosin isoforms that are sorted to subcellular compartments that have distinct morphological and dynamic properties. The creation of these compartments has a role in controlling cell morphology, cell migration and polarization of cellular components. There is increasing evidence that nonmuscle myosins are regulated by tropomyosin in these compartments via the regulation of actin attachment, ATPase kinetics, or by stabilization of cytoskeletal tracks for myosin-based transport. In this chapter, I review the literature describing the regulation of various myosins by tropomyosins and consider the mechanisms for this regulation.

How a (sub)Cellular Coincidence Detection Mechanism Featuring Layer-5 Pyramidal Cells May Help Produce Various Visual Phenomena.

PubMed

Bachmann, Talis

2015-01-01

Perceptual phenomena such as spatio-temporal illusions and masking are typically explained by psychological (cognitive) processing theories or large-scale neural theories involving inter-areal connectivity and neural circuits comprising of hundreds or more interconnected single cells. Subcellular mechanisms are hardly used for such purpose. Here, a mechanistic theoretical view is presented on how a subcellular brain mechanism of integration of presynaptic signals that arrive at different compartments of layer-5 pyramidal neurons could explain a couple of spatiotemporal visual-phenomenal effects unfolding along very brief time intervals within the range of the sub-second temporal scale.

Mercury speciation and subcellular distribution in experimentally dosed and wild birds.

PubMed

Perkins, Marie; Barst, Benjamin D; Hadrava, Justine; Basu, Niladri

2017-12-01

Many bird species are exposed to methylmercury (MeHg) at levels shown to cause sublethal effects. Although MeHg sensitivity and assimilation can vary among species and developmental stages, the underlying reasons (such as MeHg toxicokinetics) are poorly understood. We investigated Hg distribution at the tissue and cellular levels in birds by examining Hg speciation in blood, brain, and liver and Hg subcellular distribution in liver. We used MeHg egg injection of white leghorn chicken (Gallus gallus domesticus), sampled at 3 early developmental stages, and embryonic ring-billed gulls (Larus delawarensis) exposed to maternally deposited MeHg. The percentage of MeHg (relative to total Hg [THg]) in blood, brain, and liver ranged from 94 to 121%, indicating little MeHg demethylation. A liver subcellular partitioning procedure was used to determine how THg was distributed between potentially sensitive and detoxified compartments. The distributions of THg among subcellular fractions were similar among chicken time points, and between embryonic chicken and ring-billed gulls. A greater proportion of THg was associated with metal-sensitive fractions than detoxified fractions. Within the sensitive compartment, THg was found predominately in heat-denatured proteins (∼42-46%), followed by mitochondria (∼15-18%). A low rate of MeHg demethylation and high proportion of THg in metal-sensitive subcellular fractions further indicates that embryonic and hatchling time points are Hg-sensitive developmental stages, although further work is needed across a range of additional species and life stages. Environ Toxicol Chem 2017;36:3289-3298. © 2017 SETAC. © 2017 SETAC.

Solubilization of human cells by the styrene-maleic acid copolymer: Insights from fluorescence microscopy.

PubMed

Dörr, Jonas M; van Coevorden-Hameete, Marleen H; Hoogenraad, Casper C; Killian, J Antoinette

2017-11-01

Extracting membrane proteins from biological membranes by styrene-maleic acid copolymers (SMAs) in the form of nanodiscs has developed into a powerful tool in membrane research. However, the mode of action of membrane (protein) solubilization in a cellular context is still poorly understood and potential specificity for cellular compartments has not been investigated. Here, we use fluorescence microscopy to visualize the process of SMA solubilization of human cells, exemplified by the immortalized human HeLa cell line. Using fluorescent protein fusion constructs that mark distinct subcellular compartments, we found that SMA solubilizes membranes in a concentration-dependent multi-stage process. While all major intracellular compartments were affected without a strong preference, plasma membrane solubilization was found to be generally slower than the solubilization of organelle membranes. Interestingly, some plasma membrane-localized proteins were more resistant against solubilization than others, which might be explained by their presence in specific membrane domains with differing properties. Our results support the general applicability of SMA for the isolation of membrane proteins from different types of (sub)cellular membranes. Copyright © 2017 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raza, Haider; John, Annie

Tea polyphenols have been reported to be potent antioxidants and beneficial in oxidative stress related diseases. Prooxidant effects of tea polyphenols have also been reported in cell culture systems. In the present study, we have studied oxidative stress in the subcellular compartments of PC12 cells after treatment with different concentrations of the green tea polyphenol, epigallocatechin-3-gallate (EGCG). We have demonstrated that EGCG has differentially affected the production of reactive oxygen species (ROS), glutathione (GSH) metabolism and cytochrome P450 2E1 activity in the different subcellular compartments in PC12 cells. Our results have shown that although the cell survival was not inhibitedmore » by EGCG, there was, however, an increased DNA breakdown and activation of apoptotic markers, caspase 3 and poly- (ADP-ribose) polymerase (PARP) at higher concentrations of EGCG treatment. Our results suggest that the differential effects of EGCG might be related to the alterations in oxidative stress, GSH pools and CYP2E1 activity in different cellular compartments. These results may have implications in determining the chemopreventive therapeutic use of tea polyphenols in vivo.« less

The Ubiquitous Distribution of Late Embryogenesis Abundant Proteins across Cell Compartments in Arabidopsis Offers Tailored Protection against Abiotic Stress[C][W][OPEN

PubMed Central

Candat, Adrien; Paszkiewicz, Gaël; Neveu, Martine; Gautier, Romain; Logan, David C.; Avelange-Macherel, Marie-Hélène; Macherel, David

2014-01-01

Late embryogenesis abundant (LEA) proteins are hydrophilic, mostly intrinsically disordered proteins, which play major roles in desiccation tolerance. In Arabidopsis thaliana, 51 genes encoding LEA proteins clustered into nine families have been inventoried. To increase our understanding of the yet enigmatic functions of these gene families, we report the subcellular location of each protein. Experimental data highlight the limits of in silico predictions for analysis of subcellular localization. Thirty-six LEA proteins localized to the cytosol, with most being able to diffuse into the nucleus. Three proteins were exclusively localized in plastids or mitochondria, while two others were found dually targeted to these organelles. Targeting cleavage sites could be determined for five of these proteins. Three proteins were found to be endoplasmic reticulum (ER) residents, two were vacuolar, and two were secreted. A single protein was identified in pexophagosomes. While most LEA protein families have a unique subcellular localization, members of the LEA_4 family are widely distributed (cytosol, mitochondria, plastid, ER, and pexophagosome) but share the presence of the class A α-helix motif. They are thus expected to establish interactions with various cellular membranes under stress conditions. The broad subcellular distribution of LEA proteins highlights the requirement for each cellular compartment to be provided with protective mechanisms to cope with desiccation or cold stress. PMID:25005920

Monoterpene biosynthesis potential of plant subcellular compartments.

PubMed

Dong, Lemeng; Jongedijk, Esmer; Bouwmeester, Harro; Van Der Krol, Alexander

2016-01-01

Subcellular monoterpene biosynthesis capacity based on local geranyl diphosphate (GDP) availability or locally boosted GDP production was determined for plastids, cytosol and mitochondria. A geraniol synthase (GES) was targeted to plastids, cytosol, or mitochondria. Transient expression in Nicotiana benthamiana indicated local GDP availability for each compartment but resulted in different product levels. A GDP synthase from Picea abies (PaGDPS1) was shown to boost GDP production. PaGDPS1 was also targeted to plastids, cytosol or mitochondria and PaGDPS1 and GES were coexpressed in all possible combinations. Geraniol and geraniol-derived products were analyzed by GC-MS and LC-MS, respectively. GES product levels were highest for plastid-targeted GES, followed by mitochondrial- and then cytosolic-targeted GES. For each compartment local boosting of GDP biosynthesis increased GES product levels. GDP exchange between compartments is not equal: while no GDP is exchanged from the cytosol to the plastids, 100% of GDP in mitochondria can be exchanged to plastids, while only 7% of GDP from plastids is available for mitochondria. This suggests a direct exchange mechanism for GDP between plastids and mitochondria. Cytosolic PaGDPS1 competes with plastidial GES activity, suggesting an effective drain of isopentenyl diphosphate from the plastids to the cytosol. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Receptor-mediated endocytosis of asialoglycoproteins by rat liver hepatocytes: biochemical characterization of the endosomal compartments

PubMed Central

1985-01-01

The endocytic compartments of the asialoglycoprotein (ASGP) pathway in rat hepatocytes were studied using a combined morphological and biochemical approach in the isolated perfused liver. Use of electron microscopic tracers and a temperature-shift protocol to synchronize ligand entry confirmed the route of ASGP internalization observed in our previous in vivo studies (1) and established conditions under which we could label the contents of successive compartments in the pathway for subcellular fractionation studies. Three endosomal compartments were demonstrated in which ASGPs appear after they enter the cell via coated pits and vesicles but before they reach their site of degradation in lysosomes. These three compartments could be distinguished by their location within the hepatocyte, by their morphological appearance in situ, and by their density in sucrose gradients. The distributions of ASGP receptors, both accessible and latent (revealed by detergent permeabilization), were also examined and compared with that of ligand during subcellular fractionation. Most accessible ASGP receptors co-distributed with conventional plasma membrane markers. However, hepatocytes contain a substantial intracellular pool of latent ASGP binding sites that exceeds the number of cell surface receptors and whose presence is not dependent on ASGP exposure. The distribution of these latent ASGP receptors on sucrose gradients (detected either immunologically or by binding assays) was coincident with that of ligand sequestered within the early endosome compartments. In addition, both early endosomes and the membrane vesicles containing latent ASGP receptors had high cholesterol content, because both shifted markedly in density upon exposure to digitonin. PMID:2866191

Protein subcellular localization assays using split fluorescent proteins

DOEpatents

Waldo, Geoffrey S [Santa Fe, NM; Cabantous, Stephanie [Los Alamos, NM

2009-09-08

The invention provides protein subcellular localization assays using split fluorescent protein systems. The assays are conducted in living cells, do not require fixation and washing steps inherent in existing immunostaining and related techniques, and permit rapid, non-invasive, direct visualization of protein localization in living cells. The split fluorescent protein systems used in the practice of the invention generally comprise two or more self-complementing fragments of a fluorescent protein, such as GFP, wherein one or more of the fragments correspond to one or more beta-strand microdomains and are used to "tag" proteins of interest, and a complementary "assay" fragment of the fluorescent protein. Either or both of the fragments may be functionalized with a subcellular targeting sequence enabling it to be expressed in or directed to a particular subcellular compartment (i.e., the nucleus).

Spreading the news: subcellular and organellar reactive oxygen species production and signalling.

PubMed

Mignolet-Spruyt, Lorin; Xu, Enjun; Idänheimo, Niina; Hoeberichts, Frank A; Mühlenbock, Per; Brosché, Mikael; Van Breusegem, Frank; Kangasjärvi, Jaakko

2016-06-01

As plants are sessile organisms that have to attune their physiology and morphology continuously to varying environmental challenges in order to survive and reproduce, they have evolved complex and integrated environment-cell, cell-cell, and cell-organelle signalling circuits that regulate and trigger the required adjustments (such as alteration of gene expression). Although reactive oxygen species (ROS) are essential components of this network, their pathways are not yet completely unravelled. In addition to the intrinsic chemical properties that define the array of interaction partners, mobility, and stability, ROS signalling specificity is obtained via the spatiotemporal control of production and scavenging at different organellar and subcellular locations (e.g. chloroplasts, mitochondria, peroxisomes, and apoplast). Furthermore, these cellular compartments may crosstalk to relay and further fine-tune the ROS message. Hence, plant cells might locally and systemically react upon environmental or developmental challenges by generating spatiotemporally controlled dosages of certain ROS types, each with specific chemical properties and interaction targets, that are influenced by interorganellar communication and by the subcellular location and distribution of the involved organelles, to trigger the suitable acclimation responses in association with other well-established cellular signalling components (e.g. reactive nitrogen species, phytohormones, and calcium ions). Further characterization of this comprehensive ROS signalling matrix may result in the identification of new targets and key regulators of ROS signalling, which might be excellent candidates for engineering or breeding stress-tolerant plants. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Development of redox-sensitive red fluorescent proteins for imaging redox dynamics in cellular compartments.

PubMed

Fan, Yichong; Ai, Hui-wang

2016-04-01

We recently reported a redox-sensitive red fluorescent protein, rxRFP1, which is one of the first genetically encoded red-fluorescent probes for general redox states in living cells. As individual cellular compartments have different basal redox potentials, we hereby describe a group of rxRFP1 mutants, showing different midpoint redox potentials for detection of redox dynamics in various subcellular domains, such as mitochondria, the cell nucleus, and endoplasmic reticulum (ER). When these redox probes were expressed and subcellularly localized in human embryonic kidney (HEK) 293 T cells, they responded to membrane-permeable oxidants and reductants. In addition, a mitochondrially localized rxRFP1 mutant, Mito-rxRFP1.1, was used to detect mitochondrial oxidative stress induced by doxorubicin-a widely used cancer chemotherapy drug. Our work has expanded the fluorescent protein toolkit with new research tools for studying compartmentalized redox dynamics and oxidative stress under various pathophysiological conditions.

Local depletion of glycogen with supramaximal exercise in human skeletal muscle fibres

PubMed Central

Ørtenblad, Niels; Andersson, Erik; Plomgaard, Peter; Holmberg, Hans‐Christer; Nielsen, Joachim

2016-01-01

Key points Glycogen is stored in local spatially distinct compartments within skeletal muscle fibres and is the main energy source during supramaximal exercise.Using quantitative electron microscopy, we show that supramaximal exercise induces a differential depletion of glycogen from these compartments and also demonstrate how this varies with fibre types.Repeated exercise alters this compartmentalized glycogen depletion.The results obtained in the present study help us understand the muscle metabolic dynamics of whole body repeated supramaximal exercise, and suggest that the muscle has a compartmentalized local adaptation to repeated exercise, which affects glycogen depletion. Abstract Skeletal muscle glycogen is heterogeneously distributed in three separated compartments (intramyofibrillar, intermyofibrillar and subsarcolemmal). Although only constituting 3–13% of the total glycogen volume, the availability of intramyofibrillar glycogen is of particular importance to muscle function. The present study aimed to investigate the depletion of these three subcellular glycogen compartments during repeated supramaximal exercise in elite athletes. Ten elite cross‐country skiers (aged 25 ± 4 years, V˙O2 max : 65 ± 4 ml kg−1 min−1; mean ± SD) performed four ∼4 min supramaximal sprint time trials (STT 1–4) with 45 min of recovery. The subcellular glycogen volumes in musculus triceps brachii were quantified from electron microscopy images before and after both STT 1 and 4. During STT 1, the depletion of intramyofibrillar glycogen was higher in type 1 fibres [−52%; (−89:−15%)] than type 2 fibres [−15% (−52:22%)] (P = 0.02), whereas the depletion of intermyofibrillar glycogen [main effect: −19% (−33:0%), P = 0.006] and subsarcolemmal glycogen [main effect: −35% (−66:0%), P = 0.03] was similar between fibre types. By contrast, only intermyofibrillar glycogen volume was significantly reduced during STT 4, in both fibre types [main effect: −31% (−50:−11%), P = 0.002]. Furthermore, for each of the subcellular compartments, the depletion of glycogen during STT 1 was associated with the volumes of glycogen before STT 1. In conclusion, the depletion of spatially distinct glycogen compartments differs during supramaximal exercise. Furthermore, the depletion changes with repeated exercise and is fibre type‐dependent. PMID:27689320

Local depletion of glycogen with supramaximal exercise in human skeletal muscle fibres.

PubMed

Gejl, Kasper D; Ørtenblad, Niels; Andersson, Erik; Plomgaard, Peter; Holmberg, Hans-Christer; Nielsen, Joachim

2017-05-01

Glycogen is stored in local spatially distinct compartments within skeletal muscle fibres and is the main energy source during supramaximal exercise. Using quantitative electron microscopy, we show that supramaximal exercise induces a differential depletion of glycogen from these compartments and also demonstrate how this varies with fibre types. Repeated exercise alters this compartmentalized glycogen depletion. The results obtained in the present study help us understand the muscle metabolic dynamics of whole body repeated supramaximal exercise, and suggest that the muscle has a compartmentalized local adaptation to repeated exercise, which affects glycogen depletion. Skeletal muscle glycogen is heterogeneously distributed in three separated compartments (intramyofibrillar, intermyofibrillar and subsarcolemmal). Although only constituting 3-13% of the total glycogen volume, the availability of intramyofibrillar glycogen is of particular importance to muscle function. The present study aimed to investigate the depletion of these three subcellular glycogen compartments during repeated supramaximal exercise in elite athletes. Ten elite cross-country skiers (aged 25 ± 4 years, V̇O2 max : 65 ± 4 ml kg -1  min -1 ; mean ± SD) performed four ∼4 min supramaximal sprint time trials (STT 1-4) with 45 min of recovery. The subcellular glycogen volumes in musculus triceps brachii were quantified from electron microscopy images before and after both STT 1 and 4. During STT 1, the depletion of intramyofibrillar glycogen was higher in type 1 fibres [-52%; (-89:-15%)] than type 2 fibres [-15% (-52:22%)] (P = 0.02), whereas the depletion of intermyofibrillar glycogen [main effect: -19% (-33:0%), P = 0.006] and subsarcolemmal glycogen [main effect: -35% (-66:0%), P = 0.03] was similar between fibre types. By contrast, only intermyofibrillar glycogen volume was significantly reduced during STT 4, in both fibre types [main effect: -31% (-50:-11%), P = 0.002]. Furthermore, for each of the subcellular compartments, the depletion of glycogen during STT 1 was associated with the volumes of glycogen before STT 1. In conclusion, the depletion of spatially distinct glycogen compartments differs during supramaximal exercise. Furthermore, the depletion changes with repeated exercise and is fibre type-dependent. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Focal calcium monitoring with targeted nanosensors at the cytosolic side of endoplasmic reticulum

NASA Astrophysics Data System (ADS)

Hou, Yanyan; Arai, Satoshi; Takei, Yoshiaki; Murata, Atsushi; Takeoka, Shinji; Suzuki, Madoka

2016-01-01

Ca2+ distribution is spatially and temporally non-uniform inside cells due to cellular compartmentalization. However, Ca2+ sensing with small organic dyes, such as fura-2 and fluo-4, has been practically applied at a single cell level where the averaged signal from freely diffusing dye molecules is acquired. In this study, we aimed to target azide-functionalized fura-2 (N3-fura-2) to a specific site of subcellular compartments to realize focal Ca2+ sensing. Using scAVD (single-chain avidin)-biotin interaction and a copper-free click reaction system, we linked N3-fura-2 to specifically-targeted scAVD protein fused with a red fluorescent protein mCherry, so that Ca2+ sensors conjugated with four N3-fura-2 dyes with dibenzocyclooctyne (DBCO)-PEG4-biotin as a linker were generated at subcellular compartments in living cells. In cytoplasm, N3-fura-2 showed a prolonged retention period after binding to scAVD. Furthermore, the reacted N3-fura-2 was retained inside cells even after free dyes were washed out by methanol fixation. When scAVD was overexpressed on endoplasmic reticulum (ER) membranes, N3-fura-2 was accumulated on ER membranes. Upon histamine stimulation, which increases cytosolic Ca2+ concentration, ER-localized N3-fura-2 successfully sensed the Ca2+ level changes at the cytosolic side of ER membrane. Our study demonstrated specific targeting of N3-fura-2 to subcellular compartments and the ability of sensing focal Ca2+ level changes with the specifically targeted Ca2+ sensors.

High resolution imaging of subcellular glutathione concentrations by quantitative immunoelectron microscopy in different leaf areas of Arabidopsis

PubMed Central

Koffler, Barbara E.; Bloem, Elke; Zellnig, Günther; Zechmann, Bernd

2013-01-01

Glutathione is an important antioxidant and redox buffer in plants. It fulfills many important roles during plant development, defense and is essential for plant metabolism. Even though the compartment specific roles of glutathione during abiotic and biotic stress situations have been studied in detail there is still great lack of knowledge about subcellular glutathione concentrations within the different leaf areas at different stages of development. In this study a method is described that allows the calculation of compartment specific glutathione concentrations in all cell compartments simultaneously in one experiment by using quantitative immunogold electron microscopy combined with biochemical methods in different leaf areas of Arabidopsis thaliana Col-0 (center of the leaf, leaf apex, leaf base and leaf edge). The volume of subcellular compartments in the mesophyll of Arabidopsis was found to be similar to other plants. Vacuoles covered the largest volume within a mesophyll cell and increased with leaf age (up to 80% in the leaf apex of older leaves). Behind vacuoles, chloroplasts covered the second largest volume (up to 20% in the leaf edge of the younger leaves) followed by nuclei (up to 2.3% in the leaf edge of the younger leaves), mitochondria (up to 1.6% in the leaf apex of the younger leaves), and peroxisomes (up to 0.3% in the leaf apex of the younger leaves). These values together with volumes of the mesophyll determined by stereological methods from light and electron micrographs and global glutathione contents measured with biochemical methods enabled the determination of subcellular glutathione contents in mM. Even though biochemical investigations did not reveal differences in global glutathione contents, compartment specific differences could be observed in some cell compartments within the different leaf areas. Highest concentrations of glutathione were always found in mitochondria, where values in a range between 8.7 mM (in the apex of younger leaves) and 15.1 mM (in the apex of older leaves) were found. The second highest amount of glutathione was found in nuclei (between 5.5 mM and 9.7 mM in the base and the center of younger leaves, respectively) followed by peroxisomes (between 2.6 mM in the edge of younger leaves and 4.8 mM in the base of older leaves, respectively) and the cytosol (2.8 mM in the edge of younger and 4.5 mM in the center of older leaves, respectively). Chloroplasts contained rather low amounts of glutathione (between 1 mM and 1.4 mM). Vacuoles had the lowest concentrations of glutathione (0.01 mM and 0.14 mM) but showed large differences between the different leaf areas. Clear differences in glutathione contents between the different leaf areas could only be found in vacuoles and mitochondria revealing that glutathione in the later cell organelle accumulated with leaf age to concentrations of up to 15 mM and that concentrations of glutathione in vacuoles are quite low in comparison to the other cell compartments. PMID:23265941

The ubiquitin conjugating enzyme UbcH7, controls cell migration

USDA-ARS?s Scientific Manuscript database

Post translational modification by ubiquitination can target proteins for degradation, allow the interaction of proteins to form complexes or direct relocalization of proteins to different subcellular compartments. As such, ubiquitin controls a variety of essential cellular processes. Previously we ...

Activation-dependent mitochondrial translocation of Foxp3 in human hepatocytes.

PubMed

Rojas, Joselyn; Teran-Angel, Guillermo; Barbosa, Luisa; Peterson, Darrell L; Berrueta, Lisbeth; Salmen, Siham

2016-05-01

Foxp3 is considered to be the master regulator for the development and function of regulatory T cells (Treg). Recently Foxp3, has been detected in extra lymphoid tissue, and in hepatocytes and has been associated with hepatocellular carcinoma (HCC), although its role has not been defined. Since it is expected that there is a relationship between protein localization, activity and cellular function, the aim of this study was to explore the subcellular localization of Foxp3 in resting and stimulated human hepatocytes. Foxp3 expression was measured by flow cytometry, subcellular fractioning, and immunofluorescence, and this data was used to track the shuttling of Foxp3 in different subcellular compartments in hepatocytes (HepG2 cell line), stimulated by using the PKC activators (PMA), core and preS1/2 antigen from hepatitis B virus (HBV). Our data shows that besides the nuclear location, mitochondrial translocation was detected after stimulation with PMA and at to a lesser extent, with preS1/2. In addition, Foxp3 is localizes at outer mitochondrial membrane. These results suggest a non-canonical role of Foxp3 in the mitochondrial compartment in human hepatocytes, and opens a new field about their role in liver damages during HBV infection. Copyright © 2016 Elsevier Inc. All rights reserved.

Differential subcellular distribution of ion channels and the diversity of neuronal function.

PubMed

Nusser, Zoltan

2012-06-01

Following the astonishing molecular diversity of voltage-gated ion channels that was revealed in the past few decades, the ion channel repertoire expressed by neurons has been implicated as the major factor governing their functional heterogeneity. Although the molecular structure of ion channels is a key determinant of their biophysical properties, their subcellular distribution and densities on the surface of nerve cells are just as important for fulfilling functional requirements. Recent results obtained with high resolution quantitative localization techniques revealed complex, subcellular compartment-specific distribution patterns of distinct ion channels. Here I suggest that within a given neuron type every ion channel has a unique cell surface distribution pattern, with the functional consequence that this dramatically increases the computational power of nerve cells. Copyright © 2011 Elsevier Ltd. All rights reserved.

Perkinsus marinus superoxide dismutase 2 (PmSOD2) localizes to single-membrane subcellular compartments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernandez-Robledo, Jose A.; Schott, Eric J.; Vasta, Gerardo R.

2008-10-17

Perkinsus marinus (Phylum Perkinsozoa), a protozoan parasite of oysters, is considered one of the earliest diverging groups of the lineage leading to dinoflagellates. Perkinsus trophozoites are phagocytosed by oyster hemocytes, where they are likely exposed to reactive oxygen species. As part of its reactive oxygen detoxifying pathway, P. marinus possesses two iron-cofactored SOD (PmSOD1 and PmSOD2). Immunoflourescence analysis of P. marinus trophozoites and gene complementation in yeast revealed that PmSOD1 is targeted to the mitochondria. Surprisingly, although PmSOD2 is characterized by a bipartite N-terminus extension typical of plastid targeting, in preliminary immunofluorescence studies it was visualized as punctuate regions inmore » the cytoplasm that could not be assigned to any organelle. Here, we used immunogold electron microscopy to examine the subcellular localization PmSOD2 in P. marinus trophozoites. Gold grains were mostly associated with single-membrane vesicle-like structures, and eventually, localized to electron-dense, apparently amorphous material present in the lumen of a larger, unique compartment. The images suggested that PmSOD2 is targeted to small vesicles that fuse and/or discharge their content into a larger compartment, possibly the large vacuole typical of the mature trophozoites. In light of the in silico targeting prediction, the association of PmSOD2 with single-membrane compartments raises interesting questions regarding its organellar targeting, and the nature of a putative relic plastid in Perkinsus species.« less

Protein-Fragment Complementation Assays for Large-Scale Analysis, Functional Dissection, and Spatiotemporal Dynamic Studies of Protein-Protein Interactions in Living Cells.

PubMed

Michnick, Stephen W; Landry, Christian R; Levy, Emmanuel D; Diss, Guillaume; Ear, Po Hien; Kowarzyk, Jacqueline; Malleshaiah, Mohan K; Messier, Vincent; Tchekanda, Emmanuelle

2016-11-01

Protein-fragment complementation assays (PCAs) comprise a family of assays that can be used to study protein-protein interactions (PPIs), conformation changes, and protein complex dimensions. We developed PCAs to provide simple and direct methods for the study of PPIs in any living cell, subcellular compartments or membranes, multicellular organisms, or in vitro. Because they are complete assays, requiring no cell-specific components other than reporter fragments, they can be applied in any context. PCAs provide a general strategy for the detection of proteins expressed at endogenous levels within appropriate subcellular compartments and with normal posttranslational modifications, in virtually any cell type or organism under any conditions. Here we introduce a number of applications of PCAs in budding yeast, Saccharomyces cerevisiae These applications represent the full range of PPI characteristics that might be studied, from simple detection on a large scale to visualization of spatiotemporal dynamics. © 2016 Cold Spring Harbor Laboratory Press.

Co-localization of fluorescent labeled lipid nanoparticles with specifically tagged subcellular compartments by single particle tracking at low nanoparticle to cell ratios.

PubMed

Tiffany, Matthew; Szoka, Francis C

2016-11-01

We utilized quantitative high-resolution single particle tracking to study the internalization and endosomal sorting of lipid nanoparticles (LNPs) by HeLa cells in vitro to gain a better understanding of how cells process LNPs that are used for siRNA delivery. We compared the trafficking of three formulations that have been demonstrated to deliver siRNA into cells. They were composed of either a tritratable anionic lipid, formulation of cholesterol hemisuccinate (CHEMS), or a titratatable cationic lipid formulation of 1,2-dilinoleyloxy-3-dimethylaminopropane (DLinDMA) or a non-titratable cationic formulation lipid formulation of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). They also contained either a substantial percentage of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) or cholesterol and 5 mole percent 1,2-dimyristoyl-sn-glycerol-[methoxy(polyethylene glycol)-2000 (PEG-DMG). We optically measured the endosomal pH experienced by individual LNPs, observed the internalization pathways used and tracked the particles as they co-localized with fluorescent protein tags on compartment-specific proteins, during endosomal sorting to the lysosome. The data revealed significant differences in the accumulation in subcellular compartments among the three formulations, which help to explain the observed effects LNP composition exerts on in vitro delivery efficiency.

Localization of A-type K+ channel subunit Kv4.2 in rat brain.

PubMed

Tsaur, M L; Wu, Y L; Huang, F L; Shih, Y H

2001-09-30

Kv4.2, a voltage-gated K+ (Kv) channel subunit, has been suggested to be the key component of the subthreshold A-type K+ currents (I(SA)s) recorded from the specific subcellular compartments of certain CNS neurons. To correlate Kv4.2 localization with the I(SA)s detected, immunohistochemistry will be useful. Although the Kv4.2 immunostaining pattern in the hippocampus and cerebellum has been reported, the Kv4.2 antibody used was not specific. Furthermore, Kv4.2 localization in other brain regions remains unclear. In this report, we first demonstrated the specificity of a new Kv4.2 antibody, and then used it to examine Kv4.2 localization throughout adult rat brain by immunohistochemistry. At the cellular level, Kv4.2 was found in neurons but not glias. At the subcellular level, Kv4.2 was localized in the somatodendritic compartment of most neurons examined. Nevertheless, our preliminary data indicated that Kv4.2 might be also present in the axon/terminal compartment. At the functional level, our data indicates that Kv4.2 localization and I(SA) correlate quite well in some CNS neurons, supporting that Kv4.2 is the key component of some I(SA)s recorded in vivo.

Ultra-sensitive assay for paclitaxel in intracellular compartments of A549 cells using liquid chromatography-tandem mass spectrometry.

PubMed

Wang, Tingting; Ma, Wenxiao; Sun, Yantong; Yang, Yan; Zhang, Weiping; Fawcett, J Paul; Du, Hongwei; Gu, Jingkai

2013-01-01

A high-performance liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the determination of paclitaxel in intracellular compartments using docetaxel as internal standard (IS) has been developed and validated. A549 cancer cells (10(6)) were incubated with paclitaxel (2ng/mL) for up to 4h and then subjected to sequential extraction of cytosolic, membrane/organelle, nuclear and cytoskeleton soluble protein. Fractions were ultrasonicated to release protein bound paclitaxel after which drug was extracted using liquid-liquid extraction with diethyl ether:dichloromethane (2:1, v/v). Chromatographic separation was then carried out on an Ascentis Express C18 column (50mm×4.6mm, 2.7μm) with a mobile phase of acetonitrile:0.1% formic acid in water (50:50, v/v). Detection involved electrospray positive ionization followed by multiple reactions monitoring of the precursor-to-product ion transitions of paclitaxel at m/z 854.4→286.3 and docetaxel at m/z 808.6→226.1. Assay validation based on samples of total cell extract in the same buffer as protein fractions showed the assay was linear over the range 2-600pg/mL with intra- and inter-day precision (as relative standard deviation) and accuracy (as relative error) of <7% and <±12%, respectively. Recovery was approximately 70% and matrix effects were minimal. The distribution of paclitaxel in subcellular components of A549 cancer cells was mainly into the cytoskeletal compartment. Copyright © 2012 Elsevier B.V. All rights reserved.

Subcellular Localization of Pseudomonas syringae pv. tomato Effector Proteins in Plants.

PubMed

Aung, Kyaw; Xin, Xiufang; Mecey, Christy; He, Sheng Yang

2017-01-01

Animal and plant pathogenic bacteria use type III secretion systems to translocate proteinaceous effectors to subvert innate immunity of their host organisms. Type III secretion/effector systems are a crucial pathogenicity factor in many bacterial pathogens of plants and animals. Pseudomonas syringae pv. tomato (Pst) DC3000 injects a total of 36 protein effectors that target a variety of host proteins. Studies of a subset of Pst DC3000 effectors demonstrated that bacterial effectors, once inside the host cell, are localized to different subcellular compartments, including plasma membrane, cytoplasm, mitochondria, chloroplast, and Trans-Golgi network, to carry out their virulence functions. Identifying the subcellular localization of bacterial effector proteins in host cells could provide substantial clues to understanding the molecular and cellular basis of the virulence activities of effector proteins. In this chapter, we present methods for transient or stable expression of bacterial effector proteins in tobacco and/or Arabidopsis thaliana for live cell imaging as well as confirming the subcellular localization in plants using fluorescent organelle markers or chemical treatment.

Subcellular compartmentalization of Cd and Zn in two bivalves. I. Significance of metal-sensitive fractions (MSF) and biologically detoxified metal (BDM)

USGS Publications Warehouse

Wallace, W.G.; Lee, B.-G.; Luoma, S.N.

2003-01-01

Many aspects of metal accumulation in aquatic invertebrates (i.e. toxicity, tolerance and trophic transfer) can be understood by examining the subcellular partitioning of accumulated metal. In this paper, we use a compartmentalization approach to interpret the significance of metal, species and size dependence in the subcellular partitioning of Cd and Zn in the bivalves Macoma balthica and Potamocorbula amurensis. Of special interest is the compartmentalization of metal as metal-sensitive fractions (MSF) (i.e. organelles and heat-sensitive proteins, termed 'enzymes' hereafter) and biologically detoxified metal (BDM) (i.e. metallothioneins [MT] and metal-rich granules [MRG]). Clams from San Francisco Bay, CA, were exposed for 14 d to seawater (20??? salinity) containing 3.5 ??g l-1 Cd and 20.5 ??g l-1 Zn, including 109Cd and 65Zn as radiotracers. Uptake was followed by 21 d of depuration. The subcellular partitioning of metal within clams was examined following exposure and loss. P. amurensis accumulated ???22x more Cd and ???2x more Zn than M. balthica. MT played an important role in the storage of Cd in P. amurensis, while organelles were the major site of Zn accumulation. In M. balthica, Cd and Zn partitioned similarly, although the pathway of detoxification was metal-specific (MRG for Cd; MRG and MT for Zn). Upon loss, M. balthica depurated ???40% of Cd with Zn being retained; P. amurensis retained Cd and depurated Zn (???40%). During efflux, Cd and Zn concentrations in the MSF compartment of both clams declined with metal either being lost from the animal or being transferred to the BDM compartment. Subcellular compartmentalization was also size-dependent, with the importance of BDM increasing with clam size; MSF decreased accordingly. We hypothesized that progressive retention of metal as BDM (i.e. MRG) with age may lead to size dependency of metal concentrations often observed in some populations of M. balthica.

Subcellular compartmentalization of Cd and Zn in two bivalves. II. Significance of trophically available metal (TAM)

USGS Publications Warehouse

Wallace, W.G.; Luoma, S.N.

2003-01-01

This paper examines how the subcellular partitioning of Cd and Zn in the bivalves Macoma balthica and Potamocorbula amurensis may affect the trophic transfer of metal to predators. Results show that the partitioning of metals to organelles, 'enzymes' and metallothioneins (MT) comprise a subcellular compartment containing trophically available metal (TAM; i.e. metal trophically available to predators), and that because this partitioning varies with species, animal size and metal, TAM is similarly influenced. Clams from San Francisco Bay, California, were exposed for 14 d to 3.5 ??g 1-1 Cd and 20.5 ??g 1-1 Zn, including 109Cd and 65Zn as radiotracers, and were used in feeding experiments with grass shrimp Palaemon macrodatylus, or used to investigate the subcellular partitioning of metal. Grass shrimp fed Cd-contaminated P. amurensis absorbed ???60% of ingested Cd, which was in accordance with the partitioning of Cd to the bivalve's TAM compartment (i.e. Cd associated with organelles, 'enzymes' and MT); a similar relationship was found in previous studies with grass shrimp fed Cd-contaminated oligochaetes. Thus, TAM may be used as a tool to predict the trophic transfer of at least Cd. Subcellular fractionation revealed that ???34% of both the Cd and Zn accumulated by M. balthica was associated with TAM, while partitioning to TAM in P. amurensis was metal-dependent (???60% for TAM-Cd%, ???73% for TAM-Zn%). The greater TAM-Cd% of P. amurensis than M. balthica is due to preferential binding of Cd to MT and 'enzymes', while enhanced TAM-Zn% of P. amurensis results from a greater binding of Zn to organelles. TAM for most species-metal combinations was size-dependent, decreasing with increased clam size. Based on field data, it is estimated that of the 2 bivalves, P. amurensis poses the greater threat of Cd exposure to predators because of higher tissue concentrations and greater partitioning as TAM; exposure of Zn to predators would be similar between these species.

The Induction of Recombinant Protein Bodies in Different Subcellular Compartments Reveals a Cryptic Plastid-Targeting Signal in the 27-kDa γ-Zein Sequence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hofbauer, Anna; Peters, Jenny; Arcalis, Elsa

2014-12-11

Naturally occurring storage proteins such as zeins are used as fusion partners for recombinant proteins because they induce the formation of ectopic storage organelles known as protein bodies (PBs) where the proteins are stabilized by intermolecular interactions and the formation of disulfide bonds. Endogenous PBs are derived from the endoplasmic reticulum (ER). Here, we have used different targeting sequences to determine whether ectopic PBs composed of the N-terminal portion of mature 27 kDa γ-zein added to a fluorescent protein could be induced to form elsewhere in the cell. The addition of a transit peptide for targeting to plastids causes PBmore » formation in the stroma, whereas in the absence of any added targeting sequence PBs were typically associated with the plastid envelope, revealing the presence of a cryptic plastid-targeting signal within the γ-zein cysteine-rich domain. The subcellular localization of the PBs influences their morphology and the solubility of the stored recombinant fusion protein. Our results indicate that the biogenesis and budding of PBs does not require ER-specific factors and therefore, confirm that γ-zein is a versatile fusion partner for recombinant proteins offering unique opportunities for the accumulation and bioencapsulation of recombinant proteins in different subcellular compartments.« less

Mapping the subcellular localization of Fe3O4@TiO2 nanoparticles by X-ray Fluorescence Microscopy.

PubMed

Yuan, Y; Chen, S; Gleber, S C; Lai, B; Brister, K; Flachenecker, C; Wanzer, B; Paunesku, T; Vogt, S; Woloschak, G E

The targeted delivery of Fe 3 O 4 @TiO2 nanoparticles to cancer cells is an important step in their development as nanomedicines. We have synthesized nanoparticles that can bind the Epidermal Growth Factor Receptor, a cell surface protein that is overexpressed in many epithelial type cancers. In order to study the subcellular distribution of these nanoparticles, we have utilized the sub-micron resolution of X-ray Fluorescence Microscopy to map the locationof Fe 3 O4@TiO 2 NPs and other trace metal elements within HeLa cervical cancer cells. Here we demonstrate how the higher resolution of the newly installed Bionanoprobe at the Advanced Photon Source at Argonne National Laboratory can greatly improve our ability to distinguish intracellular nanoparticles and their spatial relationship with subcellular compartments.

Porcine reproductive and respiratory syndrome virus nonstructural protein 2 (nsp2) topology and selective isoform integration in artificial membranes

USDA-ARS?s Scientific Manuscript database

Membrane modification of host subcellular compartments is critical to the replication of many RNA viruses. Enveloped viruses additionally require the ability to requisition cellular membranes during egress for the development of infectious progeny. Porcine reproductive and respiratory syndrome virus...

Effects of stress on endocrine and metabolic processes and redirection: Crosstalk between subcellular compartments

USDA-ARS?s Scientific Manuscript database

Recent advances in genome analysis and biochemical pathway mapping have advanced our understanding of how biological systems have evolved over time. Protein and DNA marker comparisons suggest that several of these systems are both ancient in origin but highly conserved into today’s evolved species. ...

Remote Control of Gene Function by Local Translation

PubMed Central

Jung, Hosung; Gkogkas, Christos G.; Sonenberg, Nahum; Holt, Christine E.

2014-01-01

The subcellular position of a protein is a key determinant of its function. Mounting evidence indicates that RNA localization, where specific mRNAs are transported subcellularly and subsequently translated in response to localized signals, is an evolutionarily conserved mechanism to control protein localization. On-site synthesis confers novel signaling properties to a protein and helps to maintain local proteome homeostasis. Local translation plays particularly important roles in distal neuronal compartments, and dysregulated RNA localization and translation cause defects in neuronal wiring and survival. Here, we discuss key findings in this area and possible implications of this adaptable and swift mechanism for spatial control of gene function. PMID:24679524

Subcellular partitioning of metals in Aporrectodea caliginosa along a gradient of metal exposure in 31 field-contaminated soils.

PubMed

Beaumelle, Léa; Gimbert, Frédéric; Hedde, Mickaël; Guérin, Annie; Lamy, Isabelle

2015-07-01

Subcellular fractionation of metals in organisms was proposed as a better way to characterize metal bioaccumulation. Here we report the impact of a laboratory exposure to a wide range of field-metal contaminated soils on the subcellular partitioning of metals in the earthworm Aporrectodea caliginosa. Soils moderately contaminated were chosen to create a gradient of soil metal availability; covering ranges of both soil metal contents and of several soil parameters. Following exposure, Cd, Pb and Zn concentrations were determined both in total earthworm body and in three subcellular compartments: cytosolic, granular and debris fractions. Three distinct proxies of soil metal availability were investigated: CaCl2-extractable content dissolved content predicted by a semi-mechanistic model and free ion concentration predicted by a geochemical speciation model. Subcellular partitionings of Cd and Pb were modified along the gradient of metal exposure, while stable Zn partitioning reflected regulation processes. Cd subcellular distribution responded more strongly to increasing soil Cd concentration than the total internal content, when Pb subcellular distribution and total internal content were similarly affected. Free ion concentrations were better descriptors of Cd and Pb subcellular distribution than CaCl2 extractable and dissolved metal concentrations. However, free ion concentrations and soil total metal contents were equivalent descriptors of the subcellular partitioning of Cd and Pb because they were highly correlated. Considering lowly contaminated soils, our results raise the question of the added value of three proxies of metal availability compared to soil total metal content in the assessment of metal bioavailability to earthworm. Copyright © 2015 Elsevier B.V. All rights reserved.

Subcellular Mn compartation, anatomic and biochemical changes of two grape varieties in response to excess manganese.

PubMed

Yao, Yinan; Xu, Gang; Mou, Dongling; Wang, Junru; Ma, Jinbiao

2012-09-01

To explore the underlying mechanism for the high tolerance to excess manganese stress in the grape species (Vitis vinifera Linn), we observed the subcellular compartment of Mn element, anatomic and biochemical responses of two grape cultivars (Combier and Shuijin) under excess Mn stress in semi-controlled environmental condition. Grape species exhibited typical detoxifying or tolerant mechanism as following: first, majority of Mn element accumulated in leaf was excluded into cell wall or comparted into cell vacuole to avoid cellular Mn-toxicity; Mn and other elements were also secreted into leaf surface or deposited in vascular wall; second, only small amount of Mn was located in cellular organ, and excess Mn in chloroplast was detoxified by depositing in starch granule, which serve as a novel detoxifying strategy; additionally, the cellular Mn was further chelated by phytochelatins; third, to quench the toxic oxygen radicals, the total phenolic compounds and polyamine (putrescine and spermidine) were enhanced. Although the obvious symptom of Mn-toxicity was not detected, we observed the dessication symptom under high level of Mn treatment in the two cultivars, such as sunk stomata, thickened palisade tissue, enhanced palisade/spongy tissue ratio and abscisic acid concentration. The growth inhibition and dessication symptom in the two grape cultivars could be largely associated with osmotic stress resulted from high concentration of leaf Mn. Copyright © 2012 Elsevier Ltd. All rights reserved.

New Insights into the in situ Microscopic Visualization and Quantification of Inorganic Polyphosphate Stores by 4’,6-Diamidino-2-Phenylindole (DAPI)-Staining

PubMed Central

Gomes, F.M.; Ramos, I.B.; Wendt, C.; Girard-Dias, W.; De Souza, W.; Machado, E.A.; K. Miranda, E.A.

2013-01-01

Inorganic polyphosphate (PolyP) is a biological polymer that plays important roles in the cell physiology of both prokaryotic and eukaryotic organisms. Among the available methods for PolyP localization and quantification, a 4’,6-diamidino-2-phenylindole(DAPI)-based assay has been used for visualization of PolyP-rich organelles. Due to differences in DAPI permeability to different compartments and/or PolyP retention after fixation, a general protocol for DAPI-PolyP staining has not yet been established. Here, we tested different protocols for DAPI-PolyP detection in a range of samples with different levels of DAPI permeability, including subcellular fractions, free-living cells and cryosections of fixed tissues. Subcellular fractions of PolyP-rich organelles yielded DAPI-PolyP fluorescence, although those with a complex external layer usually required longer incubation times, previous aldehyde fixation and/or detergent permeabilization. DAPI-PolyP was also detected in cryosections of OCT-embedded tissues analyzed by multiphoton microscopy. In addition, a semi-quantitative fluorimetric analysis of DAPI-stained fractions showed PolyP mobilization in a similar fashion to what has been demonstrated with the use of enzyme-based quantitative protocols. Taken together, our results support the use of DAPI for both PolyP visualization and quantification, although specific steps are suggested as a general guideline for DAPI-PolyP staining in biological samples with different degrees of DAPI and PolyP permeability. PMID:24441187

Subcellular RNA profiling links splicing and nuclear DICER1 to alternative cleavage and polyadenylation

PubMed Central

Neve, Jonathan; Burger, Kaspar; Li, Wencheng; Hoque, Mainul; Patel, Radhika; Tian, Bin; Gullerova, Monika; Furger, Andre

2016-01-01

Alternative cleavage and polyadenylation (APA) plays a crucial role in the regulation of gene expression across eukaryotes. Although APA is extensively studied, its regulation within cellular compartments and its physiological impact remains largely enigmatic. Here, we used a rigorous subcellular fractionation approach to compare APA profiles of cytoplasmic and nuclear RNA fractions from human cell lines. This approach allowed us to extract APA isoforms that are subjected to differential regulation and provided us with a platform to interrogate the molecular regulatory pathways that shape APA profiles in different subcellular locations. Here, we show that APA isoforms with shorter 3′ UTRs tend to be overrepresented in the cytoplasm and appear to be cell-type–specific events. Nuclear retention of longer APA isoforms occurs and is partly a result of incomplete splicing contributing to the observed cytoplasmic bias of transcripts with shorter 3′ UTRs. We demonstrate that the endoribonuclease III, DICER1, contributes to the establishment of subcellular APA profiles not only by expected cytoplasmic miRNA-mediated destabilization of APA mRNA isoforms, but also by affecting polyadenylation site choice. PMID:26546131

Segmentation and quantification of subcellular structures in fluorescence microscopy images using Squassh.

PubMed

Rizk, Aurélien; Paul, Grégory; Incardona, Pietro; Bugarski, Milica; Mansouri, Maysam; Niemann, Axel; Ziegler, Urs; Berger, Philipp; Sbalzarini, Ivo F

2014-03-01

Detection and quantification of fluorescently labeled molecules in subcellular compartments is a key step in the analysis of many cell biological processes. Pixel-wise colocalization analyses, however, are not always suitable, because they do not provide object-specific information, and they are vulnerable to noise and background fluorescence. Here we present a versatile protocol for a method named 'Squassh' (segmentation and quantification of subcellular shapes), which is used for detecting, delineating and quantifying subcellular structures in fluorescence microscopy images. The workflow is implemented in freely available, user-friendly software. It works on both 2D and 3D images, accounts for the microscope optics and for uneven image background, computes cell masks and provides subpixel accuracy. The Squassh software enables both colocalization and shape analyses. The protocol can be applied in batch, on desktop computers or computer clusters, and it usually requires <1 min and <5 min for 2D and 3D images, respectively. Basic computer-user skills and some experience with fluorescence microscopy are recommended to successfully use the protocol.

Pannexin2 oligomers localize in the membranes of endosomal vesicles in mammalian cells while Pannexin1 channels traffic to the plasma membrane.

PubMed

Boassa, Daniela; Nguyen, Phuong; Hu, Junru; Ellisman, Mark H; Sosinsky, Gina E

2014-01-01

Pannexin2 (Panx2) is the largest of three members of the pannexin proteins. Pannexins are topologically related to connexins and innexins, but serve different functional roles than forming gap junctions. We previously showed that pannexins form oligomeric channels but unlike connexins and innexins, they form only single membrane channels. High levels of Panx2 mRNA and protein in the Central Nervous System (CNS) have been documented. Whereas Pannexin1 (Panx1) is fairly ubiquitous and Pannexin3 (Panx3) is found in skin and connective tissue, both are fully glycosylated, traffic to the plasma membrane and have functions correlated with extracellular ATP release. Here, we describe trafficking and subcellular localizations of exogenous Panx2 and Panx1 protein expression in MDCK, HeLa, and HEK 293T cells as well as endogenous Panx1 and Panx2 patterns in the CNS. Panx2 was found in intracellular localizations, was partially N-glycosylated, and localizations were non-overlapping with Panx1. Confocal images of hippocampal sections immunolabeled for the astrocytic protein GFAP, Panx1 and Panx2 demonstrated that the two isoforms, Panx1 and Panx2, localized at different subcellular compartments in both astrocytes and neurons. Using recombinant fusions of Panx2 with appended genetic tags developed for correlated light and electron microscopy and then expressed in different cell lines, we determined that Panx2 is localized in the membrane of intracellular vesicles and not in the endoplasmic reticulum as initially indicated by calnexin colocalization experiments. Dual immunofluorescence imaging with protein markers for specific vesicle compartments showed that Panx2 vesicles are early endosomal in origin. In electron tomographic volumes, cross-sections of these vesicles displayed fine structural details and close proximity to actin filaments. Thus, pannexins expressed at different subcellular compartments likely exert distinct functional roles, particularly in the nervous system.

Multiplexed multi-scale imaging: novel roles for the scaffold protein IQGAP1 in epithelial cell development (Conference Presentation)

NASA Astrophysics Data System (ADS)

Schweikhard, Volker

2016-02-01

The precise sub-cellular spatial localization of multi-protein complexes is increasingly recognized as a key mechanism governing the organization of mammalian cells. Consequently, there is a need for novel microscopy techniques capable of investigating such sub-cellular architectures in comprehensive detail. Here, we applied a novel multiplexed STORM super-resolution microscopy technique, in combination with high-throughput immunofluorescence microscopy and live-cell imaging, to investigate the roles of the scaffold protein IQGAP1 in epithelial cells. IQGAP1 is known to orchestrate a wide range of biological processes, including intracellular signaling, cytoskeletal regulation, cell-cell adhesion, and protein trafficking, by forming distinct complexes with a number of known interaction partners, and recruiting these complexes to specific subcellular locations. Our results demonstrate that, in addition to supporting epithelial adherens junctions by associating with specialized cortical actin structures, IQGAP1 plays a second role in which it controls the confinement of a unique, previously undocumented class of membranous compartments to the basal actin cortex. These largely immotile yet highly dynamic structures appear transiently as cells merge into clusters and establish of apical-basolateral (epithelial) polarity, and are identified as an intermediate compartment in the endocytic recycling pathways for cell junction complexes and cell surface receptors. Although these two functions of IQGAP1 occur in parallel and largely independently of each other, they both support the maturation and maintenance of polarized epithelial cell architectures.

SChloro: directing Viridiplantae proteins to six chloroplastic sub-compartments.

PubMed

Savojardo, Castrense; Martelli, Pier Luigi; Fariselli, Piero; Casadio, Rita

2017-02-01

Chloroplasts are organelles found in plants and involved in several important cell processes. Similarly to other compartments in the cell, chloroplasts have an internal structure comprising several sub-compartments, where different proteins are targeted to perform their functions. Given the relation between protein function and localization, the availability of effective computational tools to predict protein sub-organelle localizations is crucial for large-scale functional studies. In this paper we present SChloro, a novel machine-learning approach to predict protein sub-chloroplastic localization, based on targeting signal detection and membrane protein information. The proposed approach performs multi-label predictions discriminating six chloroplastic sub-compartments that include inner membrane, outer membrane, stroma, thylakoid lumen, plastoglobule and thylakoid membrane. In comparative benchmarks, the proposed method outperforms current state-of-the-art methods in both single- and multi-compartment predictions, with an overall multi-label accuracy of 74%. The results demonstrate the relevance of the approach that is eligible as a good candidate for integration into more general large-scale annotation pipelines of protein subcellular localization. The method is available as web server at http://schloro.biocomp.unibo.it gigi@biocomp.unibo.it.

Modulatory compartments in cortex and local regulation of cholinergic tone.

PubMed

Coppola, Jennifer J; Ward, Nicholas J; Jadi, Monika P; Disney, Anita A

2016-09-01

Neuromodulatory signaling is generally considered broad in its impact across cortex. However, variations in the characteristics of cortical circuits may introduce regionally-specific responses to diffuse modulatory signals. Features such as patterns of axonal innervation, tissue tortuosity and molecular diffusion, effectiveness of degradation pathways, subcellular receptor localization, and patterns of receptor expression can lead to local modification of modulatory inputs. We propose that modulatory compartments exist in cortex and can be defined by variation in structural features of local circuits. Further, we argue that these compartments are responsible for local regulation of neuromodulatory tone. For the cholinergic system, these modulatory compartments are regions of cortical tissue within which signaling conditions for acetylcholine are relatively uniform, but between which signaling can vary profoundly. In the visual system, evidence for the existence of compartments indicates that cholinergic modulation likely differs across the visual pathway. We argue that the existence of these compartments calls for thinking about cholinergic modulation in terms of finer-grained control of local cortical circuits than is implied by the traditional view of this system as a diffuse modulator. Further, an understanding of modulatory compartments provides an opportunity to better understand and perhaps correct signal modifications that lead to pathological states. Copyright © 2016 Elsevier Ltd. All rights reserved.

Phagocytosis of antibody‐opsonized tumor cells leads to the formation of a discrete vacuolar compartment in macrophages

PubMed Central

Velmurugan, Ramraj; Ramakrishnan, Sreevidhya; Kim, Mingin

2018-01-01

Despite the rapidly expanding use of antibody‐based therapeutics to treat cancer, knowledge of the cellular processes following phagocytosis of antibody‐opsonized tumor cells is limited. Here we report the formation of a phagosome‐associated vacuole that is observed in macrophages as these degradative compartments mature following phagocytosis of HER2‐positive cancer cells in the presence of the HER2‐specific antibody, trastuzumab. We demonstrate that this vacuole is a distinct organelle that is closely apposed to the phagosome. Furthermore, the size of the phagosome‐associated vacuole is increased by inhibition of the mTOR pathway. Collectively, the identification of this vacuolar compartment has implications for understanding the subcellular trafficking processes leading to the destruction of phagocytosed, antibody‐opsonized cancer cells by macrophages. PMID:29437282

Intracellular delivery and trafficking dynamics of a lymphoma-targeting antibody-polymer conjugate.

PubMed

Berguig, Geoffrey Y; Convertine, Anthony J; Shi, Julie; Palanca-Wessels, Maria Corinna; Duvall, Craig L; Pun, Suzie H; Press, Oliver W; Stayton, Patrick S

2012-12-03

Ratiometric fluorescence and cellular fractionation studies were employed to characterize the intracellular trafficking dynamics of antibody-poly(propylacrylic acid) (PPAA) conjugates in CD22+ RAMOS-AW cells. The HD39 monoclonal antibody (mAb) directs CD22-dependent, receptor-mediated uptake in human B-cell lymphoma cells, where it is rapidly trafficked to the lysosomal compartment. To characterize the intracellular-release dynamics of the polymer-mAb conjugates, HD39-streptavidin (HD39/SA) was dual-labeled with pH-insensitive Alexa Fluor 488 and pH-sensitive pHrodo fluorophores. The subcellular pH distribution of the HD39/SA-polymer conjugates was quantified as a function of time by live-cell fluorescence microscopy, and the average intracellular pH value experienced by the conjugates was also characterized as a function of time by flow cytometry. PPAA was shown to alter the intracellular trafficking kinetics strongly relative to HD39/SA alone or HD39/SA conjugates with a control polymer, poly(methacryclic acid) (PMAA). Subcellular trafficking studies revealed that after 6 h, only 11% of the HD39/SA-PPAA conjugates had been trafficked to acidic lysosomal compartments with values at or below pH 5.6. In contrast, the average intracellular pH of HD39/SA alone dropped from 6.7 ± 0.2 at 1 h to 5.6 ± 0.5 after 3 h and 4.7 ± 0.6 after 6 h. Conjugation of the control polymer PMAA to HD39/SA showed an average pH drop similar to that of HD39/SA. Subcellular fractionation studies with tritium-labeled HD39/SA demonstrated that after 6 h, 89% of HD39/SA was associated with endosomes (Rab5+) and lysosomes (Lamp2+), while 45% of HD39/SA-PPAA was translocated to the cytosol (lactate dehydrogenase+). These results demonstrate the endosomal-releasing properties of PPAA with antibody-polymer conjugates and detail their intracellular trafficking dynamics and subcellular compartmental distributions over time.

A Quantitative Spatial Proteomics Analysis of Proteome Turnover in Human Cells*

PubMed Central

Boisvert, François-Michel; Ahmad, Yasmeen; Gierliński, Marek; Charrière, Fabien; Lamont, Douglas; Scott, Michelle; Barton, Geoff; Lamond, Angus I.

2012-01-01

Measuring the properties of endogenous cell proteins, such as expression level, subcellular localization, and turnover rates, on a whole proteome level remains a major challenge in the postgenome era. Quantitative methods for measuring mRNA expression do not reliably predict corresponding protein levels and provide little or no information on other protein properties. Here we describe a combined pulse-labeling, spatial proteomics and data analysis strategy to characterize the expression, localization, synthesis, degradation, and turnover rates of endogenously expressed, untagged human proteins in different subcellular compartments. Using quantitative mass spectrometry and stable isotope labeling with amino acids in cell culture, a total of 80,098 peptides from 8,041 HeLa proteins were quantified, and their spatial distribution between the cytoplasm, nucleus and nucleolus determined and visualized using specialized software tools developed in PepTracker. Using information from ion intensities and rates of change in isotope ratios, protein abundance levels and protein synthesis, degradation and turnover rates were calculated for the whole cell and for the respective cytoplasmic, nuclear, and nucleolar compartments. Expression levels of endogenous HeLa proteins varied by up to seven orders of magnitude. The average turnover rate for HeLa proteins was ∼20 h. Turnover rate did not correlate with either molecular weight or net charge, but did correlate with abundance, with highly abundant proteins showing longer than average half-lives. Fast turnover proteins had overall a higher frequency of PEST motifs than slow turnover proteins but no general correlation was observed between amino or carboxyl terminal amino acid identities and turnover rates. A subset of proteins was identified that exist in pools with different turnover rates depending on their subcellular localization. This strongly correlated with subunits of large, multiprotein complexes, suggesting a general mechanism whereby their assembly is controlled in a different subcellular location to their main site of function. PMID:21937730

Rice proteome analysis: a step toward functional analysis of the rice genome.

PubMed

Komatsu, Setsuko; Tanaka, Naoki

2005-03-01

The technique of proteome analysis using 2-DE has the power to monitor global changes that occur in the protein complement of tissues and subcellular compartments. In this review, we describe construction of the rice proteome database, the cataloging of rice proteins, and the functional characterization of some of the proteins identified. Initially, proteins extracted from various tissues and organelles were separated by 2-DE and an image analyzer was used to construct a display or reference map of the proteins. The rice proteome database currently contains 23 reference maps based on 2-DE of proteins from different rice tissues and subcellular compartments. These reference maps comprise 13 129 rice proteins, and the amino acid sequences of 5092 of these proteins are entered in the database. Major proteins involved in growth or stress responses have been identified by using a proteomics approach and some of these proteins have unique functions. Furthermore, initial work has also begun on analyzing the phosphoproteome and protein-protein interactions in rice. The information obtained from the rice proteome database will aid in the molecular cloning of rice genes and in predicting the function of unknown proteins.

Specificity in ROS Signaling and Transcript Signatures

PubMed Central

Vaahtera, Lauri; Brosché, Mikael; Wrzaczek, Michael

2014-01-01

Abstract Significance: Reactive oxygen species (ROS), important signaling molecules in plants, are involved in developmental control and stress adaptation. ROS production can trigger broad transcriptional changes; however, it is not clear how specificity in transcriptional regulation is achieved. Recent Advances: A large collection of public transcriptome data from the model plant Arabidopsis thaliana is available for analysis. These data can be used for the analysis of biological processes that are associated with ROS signaling and for the identification of suitable transcriptional indicators. Several online tools, such as Genevestigator and Expression Angler, have simplified the task to analyze, interpret, and visualize this wealth of data. Critical Issues: The analysis of the exact transcriptional responses to ROS requires the production of specific ROS in distinct subcellular compartments with precise timing, which is experimentally difficult. Analyses are further complicated by the effect of ROS production in one subcellular location on the ROS accumulation in other compartments. In addition, even subtle differences in the method of ROS production or treatment can lead to significantly different outcomes when various stimuli are compared. Future Directions: Due to the difficulty of inducing ROS production specifically with regard to ROS type, subcellular localization, and timing, we propose that the concept of a “ROS marker gene” should be re-evaluated. We suggest guidelines for the analysis of transcriptional data in ROS signaling. The use of “ROS signatures,” which consist of a set of genes that together can show characteristic and indicative responses, should be preferred over the use of individual marker genes. Antioxid. Redox Signal. 21, 1422–1441. PMID:24180661

Targeting mechanisms of high voltage-activated Ca2+ channels.

PubMed

Herlitze, Stefan; Xie, Mian; Han, Jing; Hümmer, Alexander; Melnik-Martinez, Katya V; Moreno, Rosa L; Mark, Melanie D

2003-12-01

Functional voltage-dependent Ca2+ channel complexes are assembled by three to four subunits: alpha1, beta, alpha2delta subunits (C. Leveque et al., 1994, J. Biol Chem. 269, 6306-6312; M. W. McEnery et al., 1991, Proc. Natl. Acad. Sci. U.S.A. 88, 11095-11099) and at least in muscle cells also y subunits (B. M. Curtis and W. A. Catterall, 1984, Biochemistry 23, 2113-2118). Ca2+ channels mediate the voltage-dependent Ca2+ influx in subcellular compartments, triggering such diverse processes as neurotransmitter release, dendritic action potentials, excitation-contraction, and excitation-transcription coupling. The targeting of biophysically defined Ca2+ channel complexes to the correct subcellular structures is, thus, critical to proper cell and physiological functioning. Despite their importance, surprisingly little is known about the targeting mechanisms by which Ca2+ channel complexes are transported to their site of function. Here we summarize what we know about the targeting of Ca2+ channel complexes through the cell to the plasma membrane and subcellular structures.

High-throughput microscopy must re-invent the microscope rather than speed up its functions

PubMed Central

Oheim, M

2007-01-01

Knowledge gained from the revolutions in genomics and proteomics has helped to identify many of the key molecules involved in cellular signalling. Researchers, both in academia and in the pharmaceutical industry, now screen, at a sub-cellular level, where and when these proteins interact. Fluorescence imaging and molecular labelling combine to provide a powerful tool for real-time functional biochemistry with molecular resolution. However, they traditionally have been work-intensive, required trained personnel, and suffered from low through-put due to sample preparation, loading and handling. The need for speeding up microscopy is apparent from the tremendous complexity of cellular signalling pathways, the inherent biological variability, as well as the possibility that the same molecule plays different roles in different sub-cellular compartments. Research institutes and companies have teamed up to develop imaging cytometers of ever-increasing complexity. However, to truly go high-speed, sub-cellular imaging must free itself from the rigid framework of current microscopes. PMID:17603553

LOCALIZER: subcellular localization prediction of both plant and effector proteins in the plant cell

PubMed Central

Sperschneider, Jana; Catanzariti, Ann-Maree; DeBoer, Kathleen; Petre, Benjamin; Gardiner, Donald M.; Singh, Karam B.; Dodds, Peter N.; Taylor, Jennifer M.

2017-01-01

Pathogens secrete effector proteins and many operate inside plant cells to enable infection. Some effectors have been found to enter subcellular compartments by mimicking host targeting sequences. Although many computational methods exist to predict plant protein subcellular localization, they perform poorly for effectors. We introduce LOCALIZER for predicting plant and effector protein localization to chloroplasts, mitochondria, and nuclei. LOCALIZER shows greater prediction accuracy for chloroplast and mitochondrial targeting compared to other methods for 652 plant proteins. For 107 eukaryotic effectors, LOCALIZER outperforms other methods and predicts a previously unrecognized chloroplast transit peptide for the ToxA effector, which we show translocates into tobacco chloroplasts. Secretome-wide predictions and confocal microscopy reveal that rust fungi might have evolved multiple effectors that target chloroplasts or nuclei. LOCALIZER is the first method for predicting effector localisation in plants and is a valuable tool for prioritizing effector candidates for functional investigations. LOCALIZER is available at http://localizer.csiro.au/. PMID:28300209

Distinct Cellular and Subcellular Distributions of G Protein-Coupled Receptor Kinase and Arrestin Isoforms in the Striatum

PubMed Central

Bychkov, Evgeny; Zurkovsky, Lilia; Garret, Mika B.; Ahmed, Mohamed R.; Gurevich, Eugenia V.

2012-01-01

G protein-coupled receptor kinases (GRKs) and arrestins mediate desensitization of G protein-coupled receptors (GPCR). Arrestins also mediate G protein-independent signaling via GPCRs. Since GRK and arrestins demonstrate no strict receptor specificity, their functions in the brain may depend on their cellular complement, expression level, and subcellular targeting. However, cellular expression and subcellular distribution of GRKs and arrestins in the brain is largely unknown. We show that GRK isoforms GRK2 and GRK5 are similarly expressed in direct and indirect pathway neurons in the rat striatum. Arrestin-2 and arrestin-3 are also expressed in neurons of both pathways. Cholinergic interneurons are enriched in GRK2, arrestin-3, and GRK5. Parvalbumin-positive interneurons express more of GRK2 and less of arrestin-2 than medium spiny neurons. The GRK5 subcellular distribution in the human striatal neurons is altered by its phosphorylation: unphosphorylated enzyme preferentially localizes to synaptic membranes, whereas phosphorylated GRK5 is found in plasma membrane and cytosolic fractions. Both GRK isoforms are abundant in the nucleus of human striatal neurons, whereas the proportion of both arrestins in the nucleus was equally low. However, overall higher expression of arrestin-2 yields high enough concentration in the nucleus to mediate nuclear functions. These data suggest cell type- and subcellular compartment-dependent differences in GRK/arrestin-mediated desensitization and signaling. PMID:23139825

Distinct cellular and subcellular distributions of G protein-coupled receptor kinase and arrestin isoforms in the striatum.

PubMed

Bychkov, Evgeny; Zurkovsky, Lilia; Garret, Mika B; Ahmed, Mohamed R; Gurevich, Eugenia V

2012-01-01

G protein-coupled receptor kinases (GRKs) and arrestins mediate desensitization of G protein-coupled receptors (GPCR). Arrestins also mediate G protein-independent signaling via GPCRs. Since GRK and arrestins demonstrate no strict receptor specificity, their functions in the brain may depend on their cellular complement, expression level, and subcellular targeting. However, cellular expression and subcellular distribution of GRKs and arrestins in the brain is largely unknown. We show that GRK isoforms GRK2 and GRK5 are similarly expressed in direct and indirect pathway neurons in the rat striatum. Arrestin-2 and arrestin-3 are also expressed in neurons of both pathways. Cholinergic interneurons are enriched in GRK2, arrestin-3, and GRK5. Parvalbumin-positive interneurons express more of GRK2 and less of arrestin-2 than medium spiny neurons. The GRK5 subcellular distribution in the human striatal neurons is altered by its phosphorylation: unphosphorylated enzyme preferentially localizes to synaptic membranes, whereas phosphorylated GRK5 is found in plasma membrane and cytosolic fractions. Both GRK isoforms are abundant in the nucleus of human striatal neurons, whereas the proportion of both arrestins in the nucleus was equally low. However, overall higher expression of arrestin-2 yields high enough concentration in the nucleus to mediate nuclear functions. These data suggest cell type- and subcellular compartment-dependent differences in GRK/arrestin-mediated desensitization and signaling.

ALA-mediated PDT of melanoma tumors: light-sensitizer interactions determined by a novel spectral imaging system

NASA Astrophysics Data System (ADS)

Malik, Zvi; Dishi, M.

1995-05-01

The subcellular localization of endogenous protoporphyrin (endo- PP) during photosensitization in B-16 melanoma cells was analyzed by a novel spectral imaging system, the SpectraCube 1000. The melanoma cells were incubated with 5-aminolevulinic acid (ALA), and then the fluorescence of endo-PP was recorded in individual living cells by three modes: conventional fluorescence imaging, multipixel point by point fluorescence spectroscopy, and image processing, by operating a function of spectral similarity mapping and reconstructing new images derived from spectral information. The fluorescence image of ALA-treated cells revealed vesicular distribution of endo-PP all over the cytosol, with mitochondrial, lysosomal, as well as endoplasmic reticulum cisternael accumulation. Two main spectral fluorescence peaks were demonstrated at 635 and 705 nm, with intensities that differed from one subcellular site to another. Photoirradiation of the cells included point-specific subcellular fluorescence spectrum changes and demonstrated photoproduct formation. Spectral image reconstruction revealed the local distribution of a chosen spectrum in the photosensitized cells. On the other hand, B 16 cells treated with exogenous protoporphyrin (exo-PP) showed a dominant fluorescence peak at 670 nm and a minor peak at 630 nm. Fluorescence was localized at a perinuclear=Golgi region. Light exposure induced photobleaching and photoproduct-spectral changes followed by relocalization. The new localization at subcellular compartments showed pH dependent spectral shifts and photoproduct formation on a subcellular level.

Controlling subcellular delivery to optimize therapeutic effect

PubMed Central

Mossalam, Mohanad; Dixon, Andrew S; Lim, Carol S

2010-01-01

This article focuses on drug targeting to specific cellular organelles for therapeutic purposes. Drugs can be delivered to all major organelles of the cell (cytosol, endosome/lysosome, nucleus, nucleolus, mitochondria, endoplasmic reticulum, Golgi apparatus, peroxisomes and proteasomes) where they exert specific effects in those particular subcellular compartments. Delivery can be achieved by chemical (e.g., polymeric) or biological (e.g., signal sequences) means. Unidirectional targeting to individual organelles has proven to be immensely successful for drug therapy. Newer technologies that accommodate multiple signals (e.g., protein switch and virus-like delivery systems) mimic nature and allow for a more sophisticated approach to drug delivery. Harnessing different methods of targeting multiple organelles in a cell will lead to better drug delivery and improvements in disease therapy. PMID:21113240

Extraction of Carbon Dioxide and Hydrogen from Seawater by an Electrochemical Acidification Cell. Part 4. Electrode Compartments of Cell Modified and Tested in Scaled-Up Mobile Unit

DTIC Science & Technology

2013-09-03

Electrochemical Acidification Cell Part IV: Electrode Compartments of Cell Modified and Tested in Scaled-Up Mobile Unit September 3, 2013 Approved for public...OF ABSTRACT Extraction of Carbon Dioxide and Hydrogen from Seawater by an Electrochemical Acidification Cell Part IV: Electrode Compartments of Cell...Electrochemical acidification cell Carbon dioxide Hydrogen Polarity reversal An electrochemical acidification cell was scaled-up and integrated into a

Intracellular activation of digestive zymogens in rat pancreatic acini. Stimulation by high doses of cholecystokinin.

PubMed Central

Leach, S D; Modlin, I M; Scheele, G A; Gorelick, F S

1991-01-01

The mechanism by which digestive zymogens become activated during acute pancreatitis remains poorly understood. Given the ability for cholecystokinin (CCK) to induce pancreatitis in vivo, the effects of high dose CCK on preparations of isolated pancreatic acini were examined. Using an immunologic technique for the detection of zymogen activation, CCK was found to stimulate the conversion of procarboxypeptidase A1 to a 35-kD form having the same net charge and electrophoretic mobility as purified recombinant carboxypeptidase A1. This enhanced conversion was proportional to the dose of CCK (maximal at 100 nM), and time dependent. CCK also produced changes in the electrophoretic mobility of procarboxypeptidase B and chymotrypsinogen 2 immunoreactivity, consistent with activation of these zymogens. These events were detectable only within acinar cell pellets and not in the incubation medium, suggesting an intracellular site of conversion. The conversion of procarboxypeptidase A1 to its active form was inhibited by pretreatment with the weak base chloroquine (40 microM) and the protonophore monensin (10 microM). This conversion was also inhibited by pretreatment with the serine protease inhibitor benzamidine (10 mM) but not the cysteine protease inhibitor E64 (100 microM). The results suggest that high dose CCK stimulates the intracellular activation of digestive zymogens within isolated pancreatic acini. This event appears to require an acidic subcellular compartment and serine protease activity. Images PMID:1985109

Cellular Organization of Triacylglycerol Biosynthesis in Microalgae.

PubMed

Xu, Changcheng; Andre, Carl; Fan, Jilian; Shanklin, John

2016-01-01

Eukaryotic cells are characterized by compartmentalization and specialization of metabolism within membrane-bound organelles. Nevertheless, many fundamental processes extend across multiple subcellular compartments. Here, we describe and assess the pathways and cellular organization of triacylglycerol biosynthesis in microalgae. In particular, we emphases the dynamic interplay among the endoplasmic reticulum, lipid droplets and chloroplasts in acyl remodeling and triacylglycerol accumulation under nitrogen starvation in the model alga Chlamydomonas reinhardtii.

Repairing oxidized proteins in the bacterial envelope using respiratory chain electrons

PubMed Central

Henry, Camille; Agrebi, Rym; Vergnes, Alexandra; Oheix, Emmanuel; Bos, Julia; Leverrier, Pauline; Espinosa, Leon; Szewczyk, Joanna; Vertommen, Didier; Iranzo, Olga; Collet, Jean-François; Barras, Frédéric

2015-01-01

The reactive species of oxygen (ROS) and chlorine (RCS) damage cellular components, potentially leading to cell death. In proteins, the sulfur-containing amino acid methionine (Met) is converted to methionine sulfoxide (Met-O), which can cause a loss of biological activity. To rescue proteins with Met-O residues, living cells express methionine sulfoxide reductases (Msrs) in most subcellular compartments, including the cytosol, mitochondria and chloroplasts 1-3. Here, we report the identification of an enzymatic system, MsrPQ, repairing Met-O containing proteins in the bacterial cell envelope, a compartment particularly exposed to the ROS and RCS generated by the host defense mechanisms. MsrP, a molybdo-enzyme, and MsrQ, a heme-binding membrane protein, are widely conserved throughout Gram-negative bacteria, including major human pathogens. MsrPQ synthesis is induced by hypochlorous acid (HOCl), a powerful antimicrobial released by neutrophils. Consistently, MsrPQ is essential for the maintenance of envelope integrity under bleach stress, rescuing a wide series of structurally unrelated periplasmic proteins from Met oxidation, including the primary periplasmic chaperone SurA. For this activity, MsrPQ uses electrons from the respiratory chain, which represents a novel mechanism to import reducing equivalents into the bacterial cell envelope. A remarkable feature of MsrPQ is its capacity to reduce both R- and S- diastereoisomers of Met-O, making this oxidoreductase complex functionally different from previously identified Msrs. The discovery that a large class of bacteria contain a single, non-stereospecific enzymatic complex fully protecting Met residues from oxidation should prompt search for similar systems in eukaryotic subcellular oxidizing compartments, including the endoplasmic reticulum (ER). PMID:26641313

Repairing oxidized proteins in the bacterial envelope using respiratory chain electrons.

PubMed

Gennaris, Alexandra; Ezraty, Benjamin; Henry, Camille; Agrebi, Rym; Vergnes, Alexandra; Oheix, Emmanuel; Bos, Julia; Leverrier, Pauline; Espinosa, Leon; Szewczyk, Joanna; Vertommen, Didier; Iranzo, Olga; Collet, Jean-François; Barras, Frédéric

2015-12-17

The reactive species of oxygen and chlorine damage cellular components, potentially leading to cell death. In proteins, the sulfur-containing amino acid methionine is converted to methionine sulfoxide, which can cause a loss of biological activity. To rescue proteins with methionine sulfoxide residues, living cells express methionine sulfoxide reductases (Msrs) in most subcellular compartments, including the cytosol, mitochondria and chloroplasts. Here we report the identification of an enzymatic system, MsrPQ, repairing proteins containing methionine sulfoxide in the bacterial cell envelope, a compartment particularly exposed to the reactive species of oxygen and chlorine generated by the host defence mechanisms. MsrP, a molybdo-enzyme, and MsrQ, a haem-binding membrane protein, are widely conserved throughout Gram-negative bacteria, including major human pathogens. MsrPQ synthesis is induced by hypochlorous acid, a powerful antimicrobial released by neutrophils. Consistently, MsrPQ is essential for the maintenance of envelope integrity under bleach stress, rescuing a wide series of structurally unrelated periplasmic proteins from methionine oxidation, including the primary periplasmic chaperone SurA. For this activity, MsrPQ uses electrons from the respiratory chain, which represents a novel mechanism to import reducing equivalents into the bacterial cell envelope. A remarkable feature of MsrPQ is its capacity to reduce both rectus (R-) and sinister (S-) diastereoisomers of methionine sulfoxide, making this oxidoreductase complex functionally different from previously identified Msrs. The discovery that a large class of bacteria contain a single, non-stereospecific enzymatic complex fully protecting methionine residues from oxidation should prompt a search for similar systems in eukaryotic subcellular oxidizing compartments, including the endoplasmic reticulum.

Structure and function of yeast glutaredoxin 2 depend on postranslational processing and are related to subcellular distribution.

PubMed

Porras, Pablo; McDonagh, Brian; Pedrajas, Jose Rafael; Bárcena, J Antonio; Padilla, C Alicia

2010-04-01

We have previously shown that glutaredoxin 2 (Grx2) from Saccharomyces cerevisiae localizes at 3 different subcellular compartments, cytosol, mitochondrial matrix and outer membrane, as the result of different postranslational processing of one single gene. Having set the mechanism responsible for this remarkable phenomenon, we have now aimed at defining whether this diversity of subcellular localizations correlates with differences in structure and function of the Grx2 isoforms. We have determined the N-terminal sequence of the soluble mitochondrial matrix Grx2 by mass spectrometry and have determined the exact cleavage site by Mitochondrial Processing Peptidase (MPP). As a consequence of this cleavage, the mitochondrial matrix Grx2 isoform possesses a basic tetrapeptide extension at the N-terminus compared to the cytosolic form. A functional relationship to this structural difference is that mitochondrial Grx2 displays a markedly higher activity in the catalysis of GSSG reduction by the mitochondrial dithiol dihydrolipoamide. We have prepared Grx2 mutants affected on key residues inside the presequence to direct the protein to one single cellular compartment; either the cytosol, the mitochondrial membrane or the matrix and have analyzed their functional phenotypes. Strains expressing Grx2 only in the cytosol are equally sensitive to H(2)O(2) as strains lacking the gene, whereas those expressing Grx2 exclusively in the mitochondrial matrix are more resistant. Mutations on key basic residues drastically affect the cellular fate of the protein, showing that evolutionary diversification of Grx2 structural and functional properties are strictly dependent on the sequence of the targeting signal peptide. Copyright 2009 Elsevier B.V. All rights reserved.

Accumulation and sub-cellular partitioning of metals and As in the clam Venerupis corrugata: Different strategies towards different elements.

PubMed

Velez, Cátia; Figueira, Etelvina; Soares, Amadeu M V M; Freitas, Rosa

2016-08-01

The main goal of the present study was to assess accumulation, tolerance and sub-cellular partitioning of As, Hg, Cd and Pb in Venerupis corrugata. Results showed an increase of elements accumulation in V. corrugata with the increase of exposure. However, organisms presented higher capacity to accumulate Hg, Cd and Pb (BCF ≥ 12.8) than As (BCF ≤ 2.1) and higher accumulation rate for Cd and Pb than for Hg and As. With the increase of Hg exposure concentrations clams tended to increase the amount of metal bound to metal-sensitive fractions, which may explain the mortality recorded at the highest exposure concentration. Cd sub-cellular partitioning showed that with the increase of exposure concentrations V. corrugata increased the amount of metal in the cellular debris fraction, probably bound to the cellular membranes which explain the mortality recorded at the highest concentration. Results on As partitioning demonstrated that most of the metalloid was associated with fractions in the biologically detoxified metal compartment (BDM). Since high mortality was observed in clams exposed to As our results may indicate that this strategy was not enough to prevent clams from toxic effects and mortality occurred. When exposed to Pb most of the metal was in the BDM compartment, but in this case the metal was mostly in the metal-rich granules fraction which seemed to be efficient in preventing clams from toxicity, and no mortality was recorded. Our study further revealed that As and Hg were the most available elements to be biomagnified through the food chain. Copyright © 2016 Elsevier Ltd. All rights reserved.

Distinct Redox Regulation in Sub-Cellular Compartments in Response to Various Stress Conditions in Saccharomyces cerevisiae

PubMed Central

Ayer, Anita; Sanwald, Julia; Pillay, Bethany A.; Meyer, Andreas J.; Perrone, Gabriel G.; Dawes, Ian W.

2013-01-01

Responses to many growth and stress conditions are assumed to act via changes to the cellular redox status. However, direct measurement of pH-adjusted redox state during growth and stress has never been carried out. Organellar redox state (E GSH) was measured using the fluorescent probes roGFP2 and pHluorin in Saccharomyces cerevisiae. In particular, we investigated changes in organellar redox state in response to various growth and stress conditions to better understand the relationship between redox-, oxidative- and environmental stress response systems. E GSH values of the cytosol, mitochondrial matrix and peroxisome were determined in exponential and stationary phase in various media. These values (−340 to −350 mV) were more reducing than previously reported. Interestingly, sub-cellular redox state remained unchanged when cells were challenged with stresses previously reported to affect redox homeostasis. Only hydrogen peroxide and heat stress significantly altered organellar redox state. Hydrogen peroxide stress altered the redox state of the glutathione disulfide/glutathione couple (GSSG, 2H+/2GSH) and pH. Recovery from moderate hydrogen peroxide stress was most rapid in the cytosol, followed by the mitochondrial matrix, with the peroxisome the least able to recover. Conversely, the bulk of the redox shift observed during heat stress resulted from alterations in pH and not the GSSG, 2H+/2GSH couple. This study presents the first direct measurement of pH-adjusted redox state in sub-cellular compartments during growth and stress conditions. Redox state is distinctly regulated in organelles and data presented challenge the notion that perturbation of redox state is central in the response to many stress conditions. PMID:23762325

Sci-Thur AM: YIS – 06: A Monte Carlo study of macro- and microscopic dose descriptors and the microdosimetric spread using detailed cellular models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliver, Patricia; Thomson, Rowan

2016-08-15

Purpose: To develop Monte Carlo models of cell clusters to investigate the relationships between macro- and microscopic dose descriptors, quantify the microdosimetric spread in energy deposition for subcellular targets, and determine how these results depend on the computational model. Methods: Microscopic tissue structure is modelled as clusters of 13 to 150 cells, with cell (nuclear) radii between 5 and 10 microns (2 and 9 microns). Energy imparted per unit mass (specific energy or dose) is scored in the nucleus (D{sub nuc}) and cytoplasm (D{sub cyt}) for incident photon energies from 20 to 370 keV. Dose-to-water (D{sub w,m}) and dose-to-medium (D{submore » m,m}) are compared to D{sub nuc} and D{sub cyt}. Single cells and single nuclear cavities are also simulated. Results: D{sub nuc} and D{sub cyt} are sensitive to the surrounding environment with deviations of up to 13% for a single nucleus/cell compared with a multicellular cluster. These dose descriptors vary with cell and nucleus size by up to 10%. D{sub nuc} and D{sub cyt} differ from D{sub w,m} and D{sub m,m} by up to 32%. The microdosimetric spread is sensitive to whether cells are arranged randomly or in a hexagonal lattice, and whether subcellular compartment sizes are sampled from a normal distribution or are constant throughout the cluster. Conclusions: D{sub nuc} and D{sub cyt} are sensitive to cell morphology, elemental composition and the presence of surrounding cells. The microdosimetric spread was investigated using realistic elemental compositions for the nucleus and cytoplasm, and depends strongly on subcellular compartment size, source energy and dose.« less

Distribution of physostigmine and metabolites in brain subcellular fractions of the rat

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, B.F.; Somani, S.M.

1987-10-26

The distribution of /sup 3/H-physostigmine (Phy) has been studied in the rat brain subcellular fractions at various time intervals following i.v. injection. /sup 3/H-Phy or its metabolites rapidly accumulate into the cytoplasm of cells and penetrates the intracellular compartments. Kinetic studies of the subcellular distribution of radioactivity (RA) per gm of rat brain following i.v. injection of /sup 3/H-Phy show peak concentrations at 30 min in all subcellular fractions with the exception of mitochondria. In the mitochondrial fraction the RA levels continue to rise from 4682 +/- 875 DPM/gm at 5 min to 27,474 +/- 2825 DPM/gm at 60 minmore » (P < .05). The cytosol contains the highest RA: 223,341 +/- 21,044 DPM/gm at 30 min which declined to 53,475 +/- 3756 DPM/gm at 60 min. RA in synaptosome, microsomes and myelin increases from 5 to 30 min, and declines at 60 min. In vitro studies did not show a greater uptake of RA by the mitochondrial or synaptosomal fractions. The finding of relatively high concentrations of RA in the mitochondrial fraction at 60 min increases the likelihood that Phy or its metabolites could interfere with the physiological function of the organelle. 21 references, 1 figure, 2 tables.« less

Distribution of Single-Wall Carbon Nanotubes in the Xenopus laevis Embryo after Microinjection

PubMed Central

Holt, Brian D.; Shawky, Joseph H.; Dahl, Kris Noel; Davidson, Lance A.; Islam, Mohammad F.

2016-01-01

Single-wall carbon nanotubes (SWCNTs) are advanced materials with the potential for a myriad of diverse applications, including biological technologies and largescale usage with the potential for environmental impacts. SWCNTs have been exposed to developing organisms to determine their effects on embryogenesis, and results have been inconsistent arising, in part, from differing material quality, dispersion status, material size, impurity from catalysts, and stability. For this study, we utilized highly purified SWCNT samples with short, uniform lengths (145 ± 17 nm) well dispersed in solution. To test high exposure doses, we microinjected > 500 μg mL-1 SWCNT concentrations into the well-established embryogenesis model, Xenopus laevis, and determined embryo compatibility and sub-cellular localization during development. SWCNTs localized within cellular progeny of the microinjected cells, but heterogeneously distributed throughout the target-injected tissue. Co-registering unique Raman spectral intensity of SWCNTs with images of fluorescently labelled sub-cellular compartments demonstrated that even at the regions of highest SWCNT concentration, there were no gross alterations to sub-cellular microstructures, including filamentous actin, endoplasmic reticulum and vesicles. Furthermore, SWCNTs did not aggregate or localize to the perinuclear sub-cellular region. Combined, these results suggest that purified and dispersed SWCNTs are not toxic to X. laevis animal cap ectoderm and may be suitable candidate materials for biological applications. PMID:26510384

Influences of calcium silicate on chemical forms and subcellular distribution of cadmium in Amaranthus hypochondriacus L.

NASA Astrophysics Data System (ADS)

Lu, Huanping; Li, Zhian; Wu, Jingtao; Shen, Yong; Li, Yingwen; Zou, Bi; Tang, Yetao; Zhuang, Ping

2017-01-01

A pot experiment was conducted to investigate the effects of calcium silicate (CS) on the subcellular distribution and chemical forms of cadmium (Cd) in grain amaranths (Amaranthus hypochondriacus L. Cv. ‘K112’) grown in a Cd contaminated soil. Results showed that the dry weight and the photosynthetic pigments contents in grain amaranths increased significantly with the increasing doses of CS treatments, with the highest value found for the treatment of CS3 (1.65 g/kg). Compared with the control, application of CS4 (3.31 g/kg) significantly reduced Cd concentrations in the roots, stems and leaves of grain amaranths by 68%, 87% and 89%, respectively. At subcellular level, CS treatment resulted in redistribution of Cd, higher percentages of Cd in the chloroplast and soluble fractions in leaves of grain amaranths were found, while lower proportions of Cd were located at the cell wall of the leaves. The application of CS enhanced the proportions of pectate and protein integrated forms of Cd and decreased the percentages of water soluble Cd potentially associated with toxicity in grain amaranths. Changes of free Cd ions into inactive forms sequestered in subcellular compartments may indicate an important mechanism of CS for alleviating Cd toxicity and accumulation in plants.

Subcellular components of the amphibian egg - Insights provided by gravitational studies

NASA Technical Reports Server (NTRS)

Neff, A. W.; Ritzenthaler, J. D.; Rosenbaum, J. F.

1989-01-01

The variability in the response of Xenopus laevis eggs to a given force environment is studied. The roles of cytoplasmic organelle, the yolk platelets, and cytoskeletal components in varying in cytoplasmic mobility are examined. The data reveal that the packing of yolk platelets is not a major factor in causing cytoplasmic mobility differences and microtubules may affect cytoplasmic mobility.

Electron microscopy using the genetically encoded APEX2 tag in cultured mammalian cells

PubMed Central

Martell, Jeffrey D; Deerinck, Thomas J; Lam, Stephanie S; Ellisman, Mark H; Ting, Alice Y

2018-01-01

Electron microscopy (EM) is the premiere technique for high-resolution imaging of cellular ultrastructure. Unambiguous identification of specific proteins or cellular compartments in electron micrographs, however, remains challenging because of difficulties in delivering electron-dense contrast agents to specific subcellular targets within intact cells. We recently reported enhanced ascorbate peroxidase 2 (APEX2) as a broadly applicable genetic tag that generates EM contrast on a specific protein or subcellular compartment of interest. This protocol provides guidelines for designing and validating APEX2 fusion constructs, along with detailed instructions for cell culture, transfection, fixation, heavy-metal staining, embedding in resin, and EM imaging. Although this protocol focuses on EM in cultured mammalian cells, APEX2 is applicable to many cell types and contexts, including intact tissues and organisms, and is useful for numerous applications beyond EM, including live-cell proteomic mapping. This protocol, which describes procedures for sample preparation from cell monolayers and cell pellets, can be completed in 10 d, including time for APEX2 fusion construct validation, cell growth, and solidification of embedding resins. Notably, the only additional steps required relative to a standard EM sample preparation are cell transfection and a 2- to 45-min staining period with 3,3′-diaminobenzidine (DAB) and hydrogen peroxide (H2O2). PMID:28796234

Consistent prediction of GO protein localization.

PubMed

Spetale, Flavio E; Arce, Debora; Krsticevic, Flavia; Bulacio, Pilar; Tapia, Elizabeth

2018-05-17

The GO-Cellular Component (GO-CC) ontology provides a controlled vocabulary for the consistent description of the subcellular compartments or macromolecular complexes where proteins may act. Current machine learning-based methods used for the automated GO-CC annotation of proteins suffer from the inconsistency of individual GO-CC term predictions. Here, we present FGGA-CC + , a class of hierarchical graph-based classifiers for the consistent GO-CC annotation of protein coding genes at the subcellular compartment or macromolecular complex levels. Aiming to boost the accuracy of GO-CC predictions, we make use of the protein localization knowledge in the GO-Biological Process (GO-BP) annotations to boost the accuracy of GO-CC prediction. As a result, FGGA-CC + classifiers are built from annotation data in both the GO-CC and GO-BP ontologies. Due to their graph-based design, FGGA-CC + classifiers are fully interpretable and their predictions amenable to expert analysis. Promising results on protein annotation data from five model organisms were obtained. Additionally, successful validation results in the annotation of a challenging subset of tandem duplicated genes in the tomato non-model organism were accomplished. Overall, these results suggest that FGGA-CC + classifiers can indeed be useful for satisfying the huge demand of GO-CC annotation arising from ubiquitous high throughout sequencing and proteomic projects.

Quantitative imaging for discovery and assembly of the metabo-regulome

PubMed Central

Okumoto, Sakiko; Takanaga, Hitomi; Frommer, Wolf B.

2009-01-01

Summary Little is known about regulatory networks that control metabolic flux in plant cells. Detailed understanding of regulation is crucial for synthetic biology. The difficulty of measuring metabolites with cellular and subcellular precision is a major roadblock. New tools have been developed for monitoring extracellular, cytosolic, organellar and vacuolar ion and metabolite concentrations with a time resolution of milliseconds to hours. Genetically encoded sensors allow quantitative measurement of steady-state concentrations of ions, signaling molecules and metabolites and their respective changes over time. Fluorescence resonance energy transfer (FRET) sensors exploit conformational changes in polypeptides as a proxy for analyte concentrations. Subtle effects of analyte binding on the conformation of the recognition element are translated into a FRET change between two fused green fluorescent protein (GFP) variants, enabling simple monitoring of analyte concentrations using fluorimetry or fluorescence microscopy. Fluorimetry provides information averaged over cell populations, while microscopy detects differences between cells or populations of cells. The genetically encoded sensors can be targeted to subcellular compartments or the cell surface. Confocal microscopy ultimately permits observation of gradients or local differences within a compartment. The FRET assays can be adapted to high-throughput analysis to screen mutant populations in order to systematically identify signaling networks that control individual steps in metabolic flux. PMID:19138219

RABA Members Act in Distinct Steps of Subcellular Trafficking of the FLAGELLIN SENSING2 Receptor[W

PubMed Central

Choi, Seung-won; Tamaki, Takayuki; Ebine, Kazuo; Uemura, Tomohiro; Ueda, Takashi; Nakano, Akihiko

2013-01-01

Cell surface proteins play critical roles in the perception of environmental stimuli at the plasma membrane (PM) and ensuing signal transduction. Intracellular localization of such proteins must be strictly regulated, which requires elaborate integration of exocytic and endocytic trafficking pathways. Subcellular localization of Arabidopsis thaliana FLAGELLIN SENSING2 (FLS2), a receptor that recognizes bacterial flagellin, also depends on membrane trafficking. However, our understanding about the mechanisms involved is still limited. In this study, we visualized ligand-induced endocytosis of FLS2 using green fluorescent protein (GFP)-tagged FLS2 expressed in Nicotiana benthamiana. Upon treatment with the flg22 peptide, internalized FLS2-GFP from the PM was transported to a compartment with properties intermediate between the trans-Golgi network (TGN) and the multivesicular endosome. This compartment gradually discarded the TGN characteristics as it continued along the trafficking pathway. We further found that FLS2 endocytosis involves distinct RABA/RAB11 subgroups at different steps. Moreover, we demonstrated that transport of de novo–synthesized FLS2 to the PM also involves a distinct RABA/RAB11 subgroup. Our results demonstrate the complex regulatory system for properly localizing FLS2 and functional differentiation in RABA members in endo- and exocytosis. PMID:23532067

Theoretical Analysis of an Iron Mineral-Based Magnetoreceptor Model in Birds

PubMed Central

Solov'yov, Ilia A.; Greiner, Walter

2007-01-01

Sensing the magnetic field has been established as an essential part of navigation and orientation of various animals for many years. Only recently has the first detailed receptor concept for magnetoreception been published based on histological and physical results. The considered mechanism involves two types of iron minerals (magnetite and maghemite) that were found in subcellular compartments within sensory dendrites of the upper beak of several bird species. But so far a quantitative evaluation of the proposed receptor is missing. In this article, we develop a theoretical model to quantitatively and qualitatively describe the magnetic field effects among particles containing iron minerals. The analysis of forces acting between these subcellular compartments shows a particular dependence on the orientation of the external magnetic field. The iron minerals in the beak are found in the form of crystalline maghemite platelets and assemblies of magnetite nanoparticles. We demonstrate that the pull or push to the magnetite assemblies, which are connected to the cell membrane, may reach a value of 0.2 pN—sufficient to excite specific mechanoreceptive membrane channels in the nerve cell. The theoretical analysis of the assumed magnetoreceptor system in the avian beak skin clearly shows that it might indeed be a sensitive biological magnetometer providing an essential part of the magnetic map for navigation. PMID:17496012

Trafficking Microenvironmental pHs of Polycationic Gene Vectors in Drug-Sensitive and Multidrug-Resistant MCF7 Breast Cancer Cells

PubMed Central

Kang, Han Chang; Samsonova, Olga; Bae, You Han

2010-01-01

While multidrug resistance (MDR) has been a significant issue in cancer chemotherapy, delivery resistance to various anticancer biotherapeutics, including genes, has not been widely recognized as a property of MDR. This study aims to provide a better understanding of the transfection characteristics of drug-sensitive and drug-resistant cells by tracing microenvironmental pHs of two representative polymer vectors: poly(l-lysine) and polyethyleneimine. Drug-sensitive breast MCF7 cells had four- to seven-times higher polymeric transfection efficiencies than their counterpart drug-resistant MCF7/ADR-RES cells. Polyplexes in MCF7/ADR-RES cells after endocytosis were exposed to a more acidic microenvironment than those in MCF7 cells; the MDR cells show faster acidification rates in endosomes/lysosomes than the drug-sensitive cells after endocytosis (in the case of PLL/pDNA complexes, ~ pH 5.1 for MCF7/ADR-RES cells vs. ~ pH 6.8 for MCF7 cells at 0.5 hr post-transfection). More polyplexes were identified trapped in acidic subcellular compartments of MCF7/ADR-RES cells than in MCF7 cells, suggesting that they lack endosomal escaping activity. These findings demonstrate that the design of polymer-based gene delivery therapeutics should take into account the pH of subcellular compartments. PMID:20092888

Visible light-sensitive APTES-bound ZnO nanowire toward a potent nanoinjector sensing biomolecules in a living cell

NASA Astrophysics Data System (ADS)

Lee, Jooran; Choi, Sunyoung; Bae, Seon Joo; Yoon, Seok Min; Choi, Joon Sig; Yoon, Minjoong

2013-10-01

Nanoscale cell injection techniques combined with nanoscopic photoluminescence (PL) spectroscopy have been important issues in high-resolution optical biosensing, gene and drug delivery and single-cell endoscopy for medical diagnostics and therapeutics. However, the current nanoinjectors remain limited for optical biosensing and communication at the subwavelength level, requiring an optical probe such as semiconductor quantum dots, separately. Here, we show that waveguided red emission is observed at the tip of a single visible light-sensitive APTES-modified ZnO nanowire (APTES-ZnO NW) and it exhibits great enhancement upon interaction with a complementary sequence-based double stranded (ds) DNA, whereas it is not significantly affected by non-complementary ds DNA. Further, the tip of a single APTES-ZnO NW can be inserted into the subcellular region of living HEK 293 cells without significant toxicity, and it can also detect the enhancement of the tip emission from subcellular regions with high spatial resolution. These results indicate that the single APTES-ZnO NW would be useful as a potent nanoinjector which can guide visible light into intracellular compartments of mammalian cells, and can also detect nanoscopic optical signal changes induced by interaction with the subcellular specific target biomolecules without separate optical probes.Nanoscale cell injection techniques combined with nanoscopic photoluminescence (PL) spectroscopy have been important issues in high-resolution optical biosensing, gene and drug delivery and single-cell endoscopy for medical diagnostics and therapeutics. However, the current nanoinjectors remain limited for optical biosensing and communication at the subwavelength level, requiring an optical probe such as semiconductor quantum dots, separately. Here, we show that waveguided red emission is observed at the tip of a single visible light-sensitive APTES-modified ZnO nanowire (APTES-ZnO NW) and it exhibits great enhancement upon interaction with a complementary sequence-based double stranded (ds) DNA, whereas it is not significantly affected by non-complementary ds DNA. Further, the tip of a single APTES-ZnO NW can be inserted into the subcellular region of living HEK 293 cells without significant toxicity, and it can also detect the enhancement of the tip emission from subcellular regions with high spatial resolution. These results indicate that the single APTES-ZnO NW would be useful as a potent nanoinjector which can guide visible light into intracellular compartments of mammalian cells, and can also detect nanoscopic optical signal changes induced by interaction with the subcellular specific target biomolecules without separate optical probes. Electronic supplementary information (ESI) available: Synthesis of APTES-modified ZnO nanowires, DNA functionalization and spectroscopic measurements with additional fluorescence image ad fluorescence decay times, cell culture, injection of a single nanowire into living cells, subcellular imaging and determination of cytotoxicity. See DOI: 10.1039/c3nr03042c

Intracellular delivery and trafficking dynamics of a lymphoma-targeting antibody-polymer conjugate

PubMed Central

Berguig, Geoffrey Y.; Convertine, Anthony J.; Shi, Julie; Palanca-Wessels, Maria Corinna; Duvall, Craig L.; Pun, Suzie H.; Press, Oliver W.; Stayton, Patrick S.

2012-01-01

Ratiometric fluorescence and cellular fractionation studies were employed to characterize the intracellular trafficking dynamics of antibody-poly(propylacrylic acid) (PPAA) conjugates in CD22+ RAMOS-AW cells. The HD39 monoclonal antibody (mAb) directs CD22-dependent, receptor-mediated uptake in human B-cell lymphoma cells where it is rapidly trafficked to the lysosomal compartment. To characterize the intracellular-releasing dynamics of the polymer-mAb conjugates, HD39-streptavidin (HD39/SA) was dual-labeled with pH-insensitive Alex Fluor 488 and pH-sensitive pHrodo fluorophores. The subcellular pH-distribution of the HD39/SA-polymer conjugates were quantified as a function of time by live-cell fluorescence microscopy, and the average intracellular pH values experienced by the conjugates were also characterized as a function of time by flow cytometry. PPAA was shown to strongly alter the intracellular trafficking kinetics compared to HD39/SA alone or HD39/SA conjugates with a control polymer, poly(methacryclic acid) (PMAA). Subcellular trafficking studies revealed that after 6 hours only 11% of the HD39/SA-PPAA conjugates had been trafficked to acidic lysosomal compartments with values at or below pH 5.6. In contrast the average intracellular pH of HD39/SA alone dropped from pH 6.7 ± 0.2 at 1 hour to pH 5.6 ± 0.5 after 3 hours and pH 4.7 ± 0.6 after 6 hours. Conjugation of the control PMAA to HD39/SA showed an average pH drop similar to HD39/SA. Subcellular fractionation studies with tritium-labeled HD39/SA demonstrated that after 6 hours, 89% of HD39/SA was associated with endosomes (Rab5+) and lysosomes (Lamp2+), while 45% of HD39/SA-PPAA was translocated to the cytosol (lactate dehydrogenase+). These results demonstrate the endosomal-releasing properties of PPAA with antibody-polymer conjugates and detail their intracellular trafficking dynamics and subcellular compartmental distributions over time. PMID:23075320

Copper homeostasis in grapevine: functional characterization of the Vitis vinifera copper transporter 1.

PubMed

Martins, Viviana; Bassil, Elias; Hanana, Mohsen; Blumwald, Eduardo; Gerós, Hernâni

2014-07-01

The Vitis vinifera copper transporter 1 is capable of self-interaction and mediates intracellular copper transport. An understanding of copper homeostasis in grapevine (Vitis vinifera L.) is particularly relevant to viticulture in which copper-based fungicides are intensively used. In the present study, the Vitis vinifera copper transporter 1 (VvCTr1), belonging to the Ctr family of copper transporters, was cloned and functionally characterized. Amino acid sequence analysis showed that VvCTr1 monomers are small peptides composed of 148 amino acids with 3 transmembrane domains and several amino acid residues typical of Ctr transporters. Bimolecular fluorescence complementation (BiFC) demonstrated that Ctr monomers are self-interacting and subcellular localization studies revealed that VvCTr1 is mobilized via the trans-Golgi network, through the pre-vacuolar compartment and located to the vacuolar membrane. The heterologous expression of VvCTr1 in a yeast strain lacking all Ctr transporters fully rescued the phenotype, while a deficient complementation was observed in a strain lacking only plasma membrane-bound Ctrs. Given the common subcellular localization of VvCTr1 and AtCOPT5 and the highest amino acid sequence similarity in comparison to the remaining AtCOPT proteins, Arabidopsis copt5 plants were stably transformed with VvCTr1. The impairment in root growth observed in copt5 seedlings in copper-deficient conditions was fully rescued by VvCTr1, further supporting its involvement in intracellular copper transport. Expression studies in V. vinifera showed that VvCTr1 is mostly expressed in the root system, but transcripts were also present in leaves and stems. The functional characterization of VvCTr-mediated copper transport provides the first step towards understanding the physiological and molecular responses of grapevines to copper-based fungicides.

CESA TRAFFICKING INHIBITOR Inhibits Cellulose Deposition and Interferes with the Trafficking of Cellulose Synthase Complexes and Their Associated Proteins KORRIGAN1 and POM2/CELLULOSE SYNTHASE INTERACTIVE PROTEIN11[OPEN

PubMed Central

Wilkop, Thomas E.; Esteve, Victor Esteva; Jeannotte, Richard; Lathe, Rahul; Vernhettes, Samantha; Weimer, Bart; Hicks, Glenn; Alonso, Jose; Labavitch, John; Persson, Staffan; Ehrhardt, David; Drakakaki, Georgia

2015-01-01

Cellulose synthase complexes (CSCs) at the plasma membrane (PM) are aligned with cortical microtubules (MTs) and direct the biosynthesis of cellulose. The mechanism of the interaction between CSCs and MTs, and the cellular determinants that control the delivery of CSCs at the PM, are not yet well understood. We identified a unique small molecule, CESA TRAFFICKING INHIBITOR (CESTRIN), which reduces cellulose content and alters the anisotropic growth of Arabidopsis (Arabidopsis thaliana) hypocotyls. We monitored the distribution and mobility of fluorescently labeled cellulose synthases (CESAs) in live Arabidopsis cells under chemical exposure to characterize their subcellular effects. CESTRIN reduces the velocity of PM CSCs and causes their accumulation in the cell cortex. The CSC-associated proteins KORRIGAN1 (KOR1) and POM2/CELLULOSE SYNTHASE INTERACTIVE PROTEIN1 (CSI1) were differentially affected by CESTRIN treatment, indicating different forms of association with the PM CSCs. KOR1 accumulated in bodies similar to CESA; however, POM2/CSI1 dissociated into the cytoplasm. In addition, MT stability was altered without direct inhibition of MT polymerization, suggesting a feedback mechanism caused by cellulose interference. The selectivity of CESTRIN was assessed using a variety of subcellular markers for which no morphological effect was observed. The association of CESAs with vesicles decorated by the trans-Golgi network-localized protein SYNTAXIN OF PLANTS61 (SYP61) was increased under CESTRIN treatment, implicating SYP61 compartments in CESA trafficking. The properties of CESTRIN compared with known CESA inhibitors afford unique avenues to study and understand the mechanism under which PM-associated CSCs are maintained and interact with MTs and to dissect their trafficking routes in etiolated hypocotyls. PMID:25535279

CESA TRAFFICKING INHIBITOR inhibits cellulose deposition and interferes with the trafficking of cellulose synthase complexes and their associated proteins KORRIGAN1 and POM2/CELLULOSE SYNTHASE INTERACTIVE PROTEIN1.

PubMed

Worden, Natasha; Wilkop, Thomas E; Esteve, Victor Esteva; Jeannotte, Richard; Lathe, Rahul; Vernhettes, Samantha; Weimer, Bart; Hicks, Glenn; Alonso, Jose; Labavitch, John; Persson, Staffan; Ehrhardt, David; Drakakaki, Georgia

2015-02-01

Cellulose synthase complexes (CSCs) at the plasma membrane (PM) are aligned with cortical microtubules (MTs) and direct the biosynthesis of cellulose. The mechanism of the interaction between CSCs and MTs, and the cellular determinants that control the delivery of CSCs at the PM, are not yet well understood. We identified a unique small molecule, CESA TRAFFICKING INHIBITOR (CESTRIN), which reduces cellulose content and alters the anisotropic growth of Arabidopsis (Arabidopsis thaliana) hypocotyls. We monitored the distribution and mobility of fluorescently labeled cellulose synthases (CESAs) in live Arabidopsis cells under chemical exposure to characterize their subcellular effects. CESTRIN reduces the velocity of PM CSCs and causes their accumulation in the cell cortex. The CSC-associated proteins KORRIGAN1 (KOR1) and POM2/CELLULOSE SYNTHASE INTERACTIVE PROTEIN1 (CSI1) were differentially affected by CESTRIN treatment, indicating different forms of association with the PM CSCs. KOR1 accumulated in bodies similar to CESA; however, POM2/CSI1 dissociated into the cytoplasm. In addition, MT stability was altered without direct inhibition of MT polymerization, suggesting a feedback mechanism caused by cellulose interference. The selectivity of CESTRIN was assessed using a variety of subcellular markers for which no morphological effect was observed. The association of CESAs with vesicles decorated by the trans-Golgi network-localized protein SYNTAXIN OF PLANTS61 (SYP61) was increased under CESTRIN treatment, implicating SYP61 compartments in CESA trafficking. The properties of CESTRIN compared with known CESA inhibitors afford unique avenues to study and understand the mechanism under which PM-associated CSCs are maintained and interact with MTs and to dissect their trafficking routes in etiolated hypocotyls. © 2015 American Society of Plant Biologists. All Rights Reserved.

Amyloid precursor protein and Presenilin 1 interaction studied by FRET in human H4 cells.

PubMed

Nizzari, Mario; Venezia, Valentina; Bianchini, Paolo; Caorsi, Valentina; Diaspro, Alberto; Repetto, Emanuela; Thellung, Stefano; Corsaro, Alessandro; Carlo, Pia; Schettini, Gennaro; Florio, Tullio; Russo, Claudio

2007-01-01

The mayor pathologic hallmarks of Alzheimer's disease (AD) are senile plaque and neurofibrillary tangles. Senile plaque are primarily made up of deposits of amyloid-beta protein, a proteolytic product derived from the amyloid precursor protein (APP). APP is a transmembrane protein detected into the endoplasmic reticulum, in the Golgi apparatus, at the cell surface, recycled by endocytosis to endosomes, whose physiological function is unclear. Presenilins (PS), are a component of gamma-secretase complex that cleave alpha-CTFs (carboxy-terminal fragment), or beta-CTFs, leaving 40 or 42 amino acids amyloid-beta peptides and 58 or 56 amino acids intracellular domains (AICD). Where the amyloid-beta peptides is generated is not clear. The study of APP-PS interaction in specific cell compartments provides a good opportunity to light upon the molecular mechanisms regulating the activity of the "gamma-secretase complex," and where beta-amyloid is generated. In our study we used a biophysical assay of protein proximity: fluorescence resonance energy transfer (FRET), that can provide information about molecular interactions when two proteins are in the close proximity (<10 nm), to examine the subcellular localization and interaction between APP and PS1 in human neuroglioma cells (H4). Confocal microscopic analysis reveals extensive colocalization in different cells' compartment, and centrosomal or microtubule organizing center (MTOC) localization of APP and PS1, but not necessarily a close molecular interaction. We used FRET to determine if APP and PS1 interact at the cell centrosome. FRET data suggest a close interaction between APP and PS1 in subcellular compartments and at the centrosome of H4 cells. Using this approach we show that APP and PS1 are closely associated in the centrosomes of the H4 cell.

Protein subcellular localization prediction using artificial intelligence technology.

PubMed

Nair, Rajesh; Rost, Burkhard

2008-01-01

Proteins perform many important tasks in living organisms, such as catalysis of biochemical reactions, transport of nutrients, and recognition and transmission of signals. The plethora of aspects of the role of any particular protein is referred to as its "function." One aspect of protein function that has been the target of intensive research by computational biologists is its subcellular localization. Proteins must be localized in the same subcellular compartment to cooperate toward a common physiological function. Aberrant subcellular localization of proteins can result in several diseases, including kidney stones, cancer, and Alzheimer's disease. To date, sequence homology remains the most widely used method for inferring the function of a protein. However, the application of advanced artificial intelligence (AI)-based techniques in recent years has resulted in significant improvements in our ability to predict the subcellular localization of a protein. The prediction accuracy has risen steadily over the years, in large part due to the application of AI-based methods such as hidden Markov models (HMMs), neural networks (NNs), and support vector machines (SVMs), although the availability of larger experimental datasets has also played a role. Automatic methods that mine textual information from the biological literature and molecular biology databases have considerably sped up the process of annotation for proteins for which some information regarding function is available in the literature. State-of-the-art methods based on NNs and HMMs can predict the presence of N-terminal sorting signals extremely accurately. Ab initio methods that predict subcellular localization for any protein sequence using only the native amino acid sequence and features predicted from the native sequence have shown the most remarkable improvements. The prediction accuracy of these methods has increased by over 30% in the past decade. The accuracy of these methods is now on par with high-throughput methods for predicting localization, and they are beginning to play an important role in directing experimental research. In this chapter, we review some of the most important methods for the prediction of subcellular localization.

Electrical Identification and Selective Microstimulation of Neuronal Compartments Based on Features of Extracellular Action Potentials

NASA Astrophysics Data System (ADS)

Radivojevic, Milos; Jäckel, David; Altermatt, Michael; Müller, Jan; Viswam, Vijay; Hierlemann, Andreas; Bakkum, Douglas J.

2016-08-01

A detailed, high-spatiotemporal-resolution characterization of neuronal responses to local electrical fields and the capability of precise extracellular microstimulation of selected neurons are pivotal for studying and manipulating neuronal activity and circuits in networks and for developing neural prosthetics. Here, we studied cultured neocortical neurons by using high-density microelectrode arrays and optical imaging, complemented by the patch-clamp technique, and with the aim to correlate morphological and electrical features of neuronal compartments with their responsiveness to extracellular stimulation. We developed strategies to electrically identify any neuron in the network, while subcellular spatial resolution recording of extracellular action potential (AP) traces enabled their assignment to the axon initial segment (AIS), axonal arbor and proximal somatodendritic compartments. Stimulation at the AIS required low voltages and provided immediate, selective and reliable neuronal activation, whereas stimulation at the soma required high voltages and produced delayed and unreliable responses. Subthreshold stimulation at the soma depolarized the somatic membrane potential without eliciting APs.

Quantitative Monitoring of Subcellular Redox Dynamics in Living Mammalian Cells Using RoGFP2-Based Probes.

PubMed

Lismont, Celien; Walton, Paul A; Fransen, Marc

2017-01-01

To gain additional insight into how specific cell organelles may participate in redox signaling, it is essential to have access to tools and methodologies that are suitable to monitor spatiotemporal differences in the levels of different reactive oxygen species (ROS) and the oxidation state of specific redox couples. Over the years, the use of genetically encoded fluorescent redox indicators with a ratiometric readout has constantly gained in popularity because they can easily be targeted to various subcellular compartments and monitored in real time in single cells. Here we provide step-by-step protocols and tips for the successful use of roGFP2, a redox-sensitive variant of the enhanced green fluorescent protein, to monitor changes in glutathione redox balance and hydrogen peroxide homeostasis in the cytosol, peroxisomes, and mitochondria of mammalian cells.

mLASSO-Hum: A LASSO-based interpretable human-protein subcellular localization predictor.

PubMed

Wan, Shibiao; Mak, Man-Wai; Kung, Sun-Yuan

2015-10-07

Knowing the subcellular compartments of human proteins is essential to shed light on the mechanisms of a broad range of human diseases. In computational methods for protein subcellular localization, knowledge-based methods (especially gene ontology (GO) based methods) are known to perform better than sequence-based methods. However, existing GO-based predictors often lack interpretability and suffer from overfitting due to the high dimensionality of feature vectors. To address these problems, this paper proposes an interpretable multi-label predictor, namely mLASSO-Hum, which can yield sparse and interpretable solutions for large-scale prediction of human protein subcellular localization. By using the one-vs-rest LASSO-based classifiers, 87 out of more than 8000 GO terms are found to play more significant roles in determining the subcellular localization. Based on these 87 essential GO terms, we can decide not only where a protein resides within a cell, but also why it is located there. To further exploit information from the remaining GO terms, a method based on the GO hierarchical information derived from the depth distance of GO terms is proposed. Experimental results show that mLASSO-Hum performs significantly better than state-of-the-art predictors. We also found that in addition to the GO terms from the cellular component category, GO terms from the other two categories also play important roles in the final classification decisions. For readers' convenience, the mLASSO-Hum server is available online at http://bioinfo.eie.polyu.edu.hk/mLASSOHumServer/. Copyright © 2015 Elsevier Ltd. All rights reserved.

Subcellular localization of the Hpa RxLR effector repertoire identifies a tonoplast-associated protein HaRxL17 that confers enhanced plant susceptibility.

PubMed

Caillaud, Marie-Cécile; Piquerez, Sophie J M; Fabro, Georgina; Steinbrenner, Jens; Ishaque, Naveed; Beynon, Jim; Jones, Jonathan D G

2012-01-01

Filamentous phytopathogens form sophisticated intracellular feeding structures called haustoria in plant cells. Pathogen effectors are likely to play a role in the establishment and maintenance of haustoria in addition to their better-characterized role in suppressing plant defence. However, the specific mechanisms by which these effectors promote virulence remain unclear. To address this question, we examined changes in subcellular architecture using live-cell imaging during the compatible interaction between the oomycete Hyaloperonospora arabidopsidis (Hpa) and its host Arabidopsis. We monitored host-cell restructuring of subcellular compartments within plant mesophyll cells during haustoria ontogenesis. Live-cell imaging highlighted rearrangements in plant cell membranes upon infection, in particular to the tonoplast, which was located close to the extra-haustorial membrane surrounding the haustorium. We also investigated the subcellular localization patterns of Hpa RxLR effector candidates (HaRxLs) in planta. We identified two major classes of HaRxL effector based on localization: nuclear-localized effectors and membrane-localized effectors. Further, we identified a single effector, HaRxL17, that associated with the tonoplast in uninfected cells and with membranes around haustoria, probably the extra-haustorial membrane, in infected cells. Functional analysis of selected effector candidates in planta revealed that HaRxL17 enhances plant susceptibility. The roles of subcellular changes and effector localization, with specific reference to the potential role of HaRxL17 in plant cell membrane trafficking, are discussed with respect to Hpa virulence. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

Comparison of intracellular water content measurements by dark-field imaging and EELS in medium voltage TEM

NASA Astrophysics Data System (ADS)

Terryn, C.; Michel, J.; Kilian, L.; Bonhomme, P.; Balossier, G.

2000-09-01

Knowledge of the water content at the subcellular level is important to evaluate the intracellular concentration of either diffusible or non-diffusible elements in the physiological state measured by the electron microprobe methods. Water content variations in subcellular compartments are directly related to secretion phenomena and to transmembrane exchange processes, which could be attributed to pathophysiological states. In this paper we will describe in details and compare two local water measurement methods using analytical electron microscopy. The first one is based on darkfield imaging. It is applied on freeze-dried biological cryosections; it allows indirect measurement of the water content at the subcellular level from recorded maps of darkfield intensity. The second method uses electron energy loss spectroscopy. It is applied to hydrated biological cryosections. It is based on the differences that appear in the electron energy loss spectra of macromolecular assemblies and vitrified ice in the 0-30 eV range. By a multiple least squares (MLS) fit between an experimental energy loss spectrum and reference spectra of both frozen-hydrated ice and macromolecular assemblies we can deduce directly the local water concentration in biological cryosections at the subcellular level. These two methods are applied to two test specimens: human erythrocytes in plasma, and baker's yeast (Saccharomyses Cerevisiae) cryosections. We compare the water content measurements obtained by these two methods and discuss their advantages and drawbacks.

The src-family protein-tyrosine kinase p59hck is located on the secretory granules in human neutrophils and translocates towards the phagosome during cell activation.

PubMed

Möhn, H; Le Cabec, V; Fischer, S; Maridonneau-Parini, I

1995-07-15

The src-family protein-tyrosine kinase p59hck is mainly expressed in neutrophils; however, its functional role in these cells is unknown. Several other src-family members are localized on secretory vesicles and have been proposed to regulate intracellular traffic. We have established here the subcellular localization of p59hck in human neutrophils. Immunoblotting of subcellular fractions showed that approx. 60% of the p59hck per cell is localized on the secretory granules; the other 40% is distributed equally between non-granular membranes and the cytosol. Immunofluorescence of neutrophils and HL60 cells suggests that the p59hck-positive granules are azurophil granules. Granular p59hck is highly susceptible to degradation by an azurophil-granule proteinase. Different forms of p59hck occur in the three subcellular compartments: a 61 kDa form is mainly found in the granules, a 59 kDa form is predominant in the non-granular membranes, whereas cytosolic p59hck migrates as a doublet at 63 kDa. During the process of phagocytosis-linked degranulation, induced by serum-opsonized zymosan in neutrophils or HL60 cells, granular p59hck translocates towards the phagosome. The subcellular localization of p59hck suggests that the enzyme could be involved in the regulation of the degranulation process.

Learning from Heterogeneous Data Sources: An Application in Spatial Proteomics

PubMed Central

Breckels, Lisa M.; Holden, Sean B.; Wojnar, David; Mulvey, Claire M.; Christoforou, Andy; Groen, Arnoud; Trotter, Matthew W. B.; Kohlbacher, Oliver; Lilley, Kathryn S.; Gatto, Laurent

2016-01-01

Sub-cellular localisation of proteins is an essential post-translational regulatory mechanism that can be assayed using high-throughput mass spectrometry (MS). These MS-based spatial proteomics experiments enable us to pinpoint the sub-cellular distribution of thousands of proteins in a specific system under controlled conditions. Recent advances in high-throughput MS methods have yielded a plethora of experimental spatial proteomics data for the cell biology community. Yet, there are many third-party data sources, such as immunofluorescence microscopy or protein annotations and sequences, which represent a rich and vast source of complementary information. We present a unique transfer learning classification framework that utilises a nearest-neighbour or support vector machine system, to integrate heterogeneous data sources to considerably improve on the quantity and quality of sub-cellular protein assignment. We demonstrate the utility of our algorithms through evaluation of five experimental datasets, from four different species in conjunction with four different auxiliary data sources to classify proteins to tens of sub-cellular compartments with high generalisation accuracy. We further apply the method to an experiment on pluripotent mouse embryonic stem cells to classify a set of previously unknown proteins, and validate our findings against a recent high resolution map of the mouse stem cell proteome. The methodology is distributed as part of the open-source Bioconductor pRoloc suite for spatial proteomics data analysis. PMID:27175778

Identification of human cysteine-rich secretory protein 3 (CRISP-3) as a matrix protein in a subset of peroxidase-negative granules of neutrophils and in the granules of eosinophils.

PubMed

Udby, Lene; Calafat, Jero; Sørensen, Ole E; Borregaard, Niels; Kjeldsen, Lars

2002-09-01

Cysteine-rich secretory protein 3 (CRISP-3; also known as SGP28) was originally discovered in human neutrophilic granulocytes. We have recently developed a sensitive sandwich enzyme-linked immunosorbent assay for CRISP-3 and demonstrated the presence of CRISP-3 in exocrine secretions. To investigate the subcellular localization and mobilization of CRISP-3 in human neutrophils, we performed subcellular fractionation of resting and activated neutrophils on three-layer Percoll density gradients, release-studies of granule proteins in response to different secretagogues, and double-labeling immunogold electron microscopy. CRISP-3 was found to be localized in a subset of granules with overlapping characteristics of specific and gelatinase granules and mobilized accordingly, thus confirming the hypothesis that peroxidase-negative granules exist as a continuum from specific to gelatinase granules regarding protein content and mobilization. CRISP-3 was found to be a matrix protein, which is stored in granules as glycosylated and as unglycosylated protein. The subcellular distribution of the two forms of CRISP-3 was identical. In addition, CRISP-3 was found as a granule protein in eosinophilic granulocytes. The presence of CRISP-3 in peroxidase-negative granules of neutrophils, in granules of eosinophils, and in exocrine secretions indicates a role in the innate host defense.

Essential basal cytonemes take up Hedgehog in the Drosophila wing imaginal disc.

PubMed

Chen, Weitao; Huang, Hai; Hatori, Ryo; Kornberg, Thomas B

2017-09-01

Morphogen concentration gradients that extend across developmental fields form by dispersion from source cells. In the Drosophila wing disc, Hedgehog (Hh) produced by posterior compartment cells distributes in a concentration gradient to adjacent cells of the anterior compartment. We monitored Hh:GFP after pulsed expression, and analyzed the movement and colocalization of Hh, Patched (Ptc) and Smoothened (Smo) proteins tagged with GFP or mCherry and expressed at physiological levels from bacterial artificial chromosome transgenes. Hh:GFP moved to basal subcellular locations prior to release from posterior compartment cells that express it, and was taken up by basal cytonemes that extend to the source cells. Hh and Ptc were present in puncta that moved along the basal cytonemes and formed characteristic apical-basal distributions in the anterior compartment cells. The basal cytonemes required diaphanous , SCAR , N euroglian and S ynaptobrevin , and both the Hh gradient and Hh signaling declined under conditions in which the cytonemes were compromised. These findings show that in the wing disc, Hh distributions and signaling are dependent upon basal release and uptake, and on cytoneme-mediated movement. No evidence for apical dispersion was obtained. © 2017. Published by The Company of Biologists Ltd.

Nucleoli and stress granules: connecting distant relatives.

PubMed

Mahboubi, Hicham; Stochaj, Ursula

2014-10-01

Nucleoli and cytoplasmic stress granules (SGs) are subcellular compartments that modulate the response to endogenous and environmental signals to control cell survival. In our opinion, nucleoli and SGs are functionally linked; they are distant relatives that combine forces when cellular homeostasis is threatened. Several lines of evidence support this idea; nucleoli and SGs share molecular building blocks, are regulated by common signaling pathways and communicate when vital cellular functions become compromised. Together, nucleoli and SGs orchestrate physiological responses that are directly relevant to stress and human health. As both compartments have established roles in neurodegenerative diseases, cancer and virus infections, we propose that these conditions will benefit from therapeutic interventions that target simultaneously nucleoli and SGs. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Biomimetic enzyme nanocomplexes and their use as antidotes and preventive measures for alcohol intoxication

NASA Astrophysics Data System (ADS)

Liu, Yang; Du, Juanjuan; Yan, Ming; Lau, Mo Yin; Hu, Jay; Han, Hui; Yang, Otto O.; Liang, Sheng; Wei, Wei; Wang, Hui; Li, Jianmin; Zhu, Xinyuan; Shi, Linqi; Chen, Wei; Ji, Cheng; Lu, Yunfeng

2013-03-01

Organisms have sophisticated subcellular compartments containing enzymes that function in tandem. These confined compartments ensure effective chemical transformation and transport of molecules, and the elimination of toxic metabolic wastes. Creating functional enzyme complexes that are confined in a similar way remains challenging. Here we show that two or more enzymes with complementary functions can be assembled and encapsulated within a thin polymer shell to form enzyme nanocomplexes. These nanocomplexes exhibit improved catalytic efficiency and enhanced stability when compared with free enzymes. Furthermore, the co-localized enzymes display complementary functions, whereby toxic intermediates generated by one enzyme can be promptly eliminated by another enzyme. We show that nanocomplexes containing alcohol oxidase and catalase could reduce blood alcohol levels in intoxicated mice, offering an alternative antidote and prophylactic for alcohol intoxication.

Tissue-specific accumulation of cadmium in subcellular compartments of eastern oysters Crassostrea virginica Gmelin (Bivalvia: Ostreidae).

PubMed

Sokolova, I M; Ringwood, A H; Johnson, C

2005-09-10

Cadmium distribution was studied in different subcellular fractions of gill and hepatopancreas tissues of eastern oysters Crassostrea virginica. Oysters were exposed for up to 21 days to low sublethal Cd concentrations (25 microg L(-1)). Gill and hepatopancreas tissues were sampled and divided into organelle fractions and cytosol by differential centrifugation. Organelle content of different fractions was verified by activities of marker enzymes, citrate synthase and acid phosphatase for mitochondria and lysosomes, respectively. In both tissue types, there was a significant accumulation of cadmium in cytosol reaching 230-350 ng mg(-1) protein. Among organelles, mitochondria were the main target for Cd bioaccumulation in gills (250-300 ng mg(-1) protein), whereas in hepatopancreas tissues, the highest cadmium accumulation occurred in lysosomes (90-94 ng mg(-1) protein). Although 75-83% of total cadmium burden was associated with the cytosol reflecting high volume fraction of this compartment, Cd concentrations in organelle fractions reached levels that could cause dysfunction of mitochondria and lysosomes. Organ- and organelle-specific patterns of cadmium bioaccumulation support our previous in vivo studies, which showed adverse effects of cadmium exposures on mitochondrial oxidation in gills and on the lysosomal system of hepatopancreas. This may have important implications for the development of biomarkers of effect for heavy metals and for understanding the mechanisms of toxic effects of metals.

Cystic Fibrosis, Cystic Fibrosis Transmembrane Conductance Regulator and Drugs: Insights from Cellular Trafficking.

PubMed

Bridges, Robert J; Bradbury, Neil A

2018-01-01

The eukaryotic cell is organized into membrane-delineated compartments that are characterized by specific cadres of proteins sustaining biochemically distinct cellular processes. The appropriate subcellular localization of proteins is key to proper organelle function and provides a physiological context for cellular processes. Disruption of normal trafficking pathways for proteins is seen in several genetic diseases, where a protein's absence for a specific subcellular compartment leads to organelle disruption, and in the context of an individual, a disruption of normal physiology. Importantly, several drug therapies can also alter protein trafficking, causing unwanted side effects. Thus, a deeper understanding of trafficking pathways needs to be appreciated as novel therapeutic modalities are proposed. Despite the promising efficacy of novel therapeutic agents, the intracellular bioavailability of these compounds has proved to be a potential barrier, leading to failures in treatments for various diseases and disorders. While endocytosis of drug moieties provides an efficient means of getting material into cells, the subsequent release and endosomal escape of materials into the cytosol where they need to act has been a barrier. An understanding of cellular protein/lipid trafficking pathways has opened up strategies for increasing drug bioavailability. Approaches to enhance endosomal exit have greatly increased the cytosolic bioavailability of drugs and will provide a means of investigating previous drugs that may have been shelved due to their low cytosolic concentration.

Nutrient-dependent phosphorylation channels lipid synthesis to regulate PPARα

PubMed Central

Jensen-Urstad, Anne P. L.; Song, Haowei; Lodhi, Irfan J.; Funai, Katsuhiko; Yin, Li; Coleman, Trey; Semenkovich, Clay F.

2013-01-01

Peroxisome proliferator-activated receptor (PPAR)α is a nuclear receptor that coordinates liver metabolism during fasting. Fatty acid synthase (FAS) is an enzyme that stores excess calories as fat during feeding, but it also activates hepatic PPARα by promoting synthesis of an endogenous ligand. Here we show that the mechanism underlying this paradoxical relationship involves the differential regulation of FAS in at least two distinct subcellular pools: cytoplasmic and membrane-associated. In mouse liver and cultured hepatoma cells, the ratio of cytoplasmic to membrane FAS-specific activity was increased with fasting, indicating higher cytoplasmic FAS activity under conditions associated with PPARα activation. This effect was due to a nutrient-dependent and compartment-selective covalent modification of FAS. Cytoplasmic FAS was preferentially phosphorylated during feeding or insulin treatment at Thr-1029 and Thr-1033, which flank a dehydratase domain catalytic residue. Mutating these sites to alanines promoted PPARα target gene expression. Rapamycin-induced inhibition of mammalian/mechanistic target of rapamycin complex 1 (mTORC1), a mediator of the feeding/insulin signal to induce lipogenesis, reduced FAS phosphorylation, increased cytoplasmic FAS enzyme activity, and increased PPARα target gene expression. Rapamycin-mediated induction of the same gene was abrogated with FAS knockdown. These findings suggest that hepatic FAS channels lipid synthesis through specific subcellular compartments that allow differential gene expression based on nutritional status. PMID:23585690

The Expression Level of Septin12 Is Critical for Spermiogenesis

PubMed Central

Lin, Ying-Hung; Lin, Yung-Ming; Wang, Ya-Yun; Yu, I-Shing; Lin, Yi-Wen; Wang, Yun-Han; Wu, Ching-Ming; Pan, Hsien-An; Chao, Shin-Chih; Yen, Pauline H.; Lin, Shu-Wha; Kuo, Pao-Lin

2009-01-01

Septins belong to a family of polymerizing GTP-binding proteins that are required for many cellular functions, such as membrane compartmentalization, vesicular trafficking, mitosis, and cytoskeletal remodeling. One family member, septin12, is expressed specifically in the testis. In this study, we found septin12 expressed in multiple subcellular compartments during terminal differentiation of mouse germ cells. In humans, the testicular tissues of men with either hypospermatogenesis or maturation arrest had lower levels of SEPTIN12 transcripts than normal men. In addition, increased numbers of spermatozoa with abnormal head, neck, and tail morphologies lacked SEPT12 immunostaining signals, as compared with normal spermatozoa. To elucidate the role of septin12, we generated 129 embryonic stem cells containing a septin12 mutant allele with a deletion in the exons that encode the N-terminal GTP-binding domain. Most chimeras derived from the targeted embryonic stem cells were infertile, and the few fertile chimeras only produced offspring with a C57BL/6 background. Semen analysis of the infertile chimeras showed a decreased sperm count, decreased sperm motility, and spermatozoa with defects involving all subcellular compartments. The testicular phenotypes included maturation arrest of germ cells at the spermatid stage, sloughing of round spermatids, and increased apoptosis of germ cells. Electron microscopic examination of spermatozoa showed misshapen nuclei, disorganized mitochondria, and broken acrosomes. Our data indicate that Septin12 expression levels are critical for mammalian spermiogenesis. PMID:19359518

Multiple marker abundance profiling: combining selected reaction monitoring and data-dependent acquisition for rapid estimation of organelle abundance in subcellular samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hooper, Cornelia M.; Stevens, Tim J.; Saukkonen, Anna

Measuring changes in protein or organelle abundance in the cell is an essential, but challenging aspect of cell biology. Frequently-used methods for determining organelle abundance typically rely on detection of a very few marker proteins, so are unsatisfactory. In silico estimates of protein abundances from publicly available protein spectra can provide useful standard abundance values but contain only data from tissue proteomes, and are not coupled to organelle localization data. A new protein abundance score, the normalized protein abundance scale (NPAS), expands on the number of scored proteins and the scoring accuracy of lower-abundance proteins in Arabidopsis. NPAS was combinedmore » with subcellular protein localization data, facilitating quantitative estimations of organelle abundance during routine experimental procedures. A suite of targeted proteomics markers for subcellular compartment markers was developed, enabling independent verification of in silico estimates for relative organelle abundance. Estimation of relative organelle abundance was found to be reproducible and consistent over a range of tissues and growth conditions. In silico abundance estimations and localization data have been combined into an online tool, multiple marker abundance profiling, available in the SUBA4 toolbox (http://suba.live).« less

Multiple marker abundance profiling: combining selected reaction monitoring and data-dependent acquisition for rapid estimation of organelle abundance in subcellular samples

DOE PAGES

Hooper, Cornelia M.; Stevens, Tim J.; Saukkonen, Anna; ...

2017-10-12

Measuring changes in protein or organelle abundance in the cell is an essential, but challenging aspect of cell biology. Frequently-used methods for determining organelle abundance typically rely on detection of a very few marker proteins, so are unsatisfactory. In silico estimates of protein abundances from publicly available protein spectra can provide useful standard abundance values but contain only data from tissue proteomes, and are not coupled to organelle localization data. A new protein abundance score, the normalized protein abundance scale (NPAS), expands on the number of scored proteins and the scoring accuracy of lower-abundance proteins in Arabidopsis. NPAS was combinedmore » with subcellular protein localization data, facilitating quantitative estimations of organelle abundance during routine experimental procedures. A suite of targeted proteomics markers for subcellular compartment markers was developed, enabling independent verification of in silico estimates for relative organelle abundance. Estimation of relative organelle abundance was found to be reproducible and consistent over a range of tissues and growth conditions. In silico abundance estimations and localization data have been combined into an online tool, multiple marker abundance profiling, available in the SUBA4 toolbox (http://suba.live).« less

Subcellular Investigation of Photosynthesis-Driven Carbon Assimilation in the Symbiotic Reef Coral Pocillopora damicornis

PubMed Central

Domart-Coulon, Isabelle; Escrig, Stephane; Humbel, Bruno M.; Hignette, Michel

2015-01-01

ABSTRACT  Reef-building corals form essential, mutualistic endosymbiotic associations with photosynthetic Symbiodinium dinoflagellates, providing their animal host partner with photosynthetically derived nutrients that allow the coral to thrive in oligotrophic waters. However, little is known about the dynamics of these nutritional interactions at the (sub)cellular level. Here, we visualize with submicrometer spatial resolution the carbon and nitrogen fluxes in the intact coral-dinoflagellate association from the reef coral Pocillopora damicornis by combining nanoscale secondary ion mass spectrometry (NanoSIMS) and transmission electron microscopy with pulse-chase isotopic labeling using [13C]bicarbonate and [15N]nitrate. This allows us to observe that (i) through light-driven photosynthesis, dinoflagellates rapidly assimilate inorganic bicarbonate and nitrate, temporarily storing carbon within lipid droplets and starch granules for remobilization in nighttime, along with carbon and nitrogen incorporation into other subcellular compartments for dinoflagellate growth and maintenance, (ii) carbon-containing photosynthates are translocated to all four coral tissue layers, where they accumulate after only 15 min in coral lipid droplets from the oral gastroderm and within 6 h in glycogen granules from the oral epiderm, and (iii) the translocation of nitrogen-containing photosynthates is delayed by 3 h. PMID:25670779

LocSigDB: a database of protein localization signals

PubMed Central

Negi, Simarjeet; Pandey, Sanjit; Srinivasan, Satish M.; Mohammed, Akram; Guda, Chittibabu

2015-01-01

LocSigDB (http://genome.unmc.edu/LocSigDB/) is a manually curated database of experimental protein localization signals for eight distinct subcellular locations; primarily in a eukaryotic cell with brief coverage of bacterial proteins. Proteins must be localized at their appropriate subcellular compartment to perform their desired function. Mislocalization of proteins to unintended locations is a causative factor for many human diseases; therefore, collection of known sorting signals will help support many important areas of biomedical research. By performing an extensive literature study, we compiled a collection of 533 experimentally determined localization signals, along with the proteins that harbor such signals. Each signal in the LocSigDB is annotated with its localization, source, PubMed references and is linked to the proteins in UniProt database along with the organism information that contain the same amino acid pattern as the given signal. From LocSigDB webserver, users can download the whole database or browse/search for data using an intuitive query interface. To date, LocSigDB is the most comprehensive compendium of protein localization signals for eight distinct subcellular locations. Database URL: http://genome.unmc.edu/LocSigDB/ PMID:25725059

Trehalose Alters Subcellular Trafficking and the Metabolism of the Alzheimer-associated Amyloid Precursor Protein*

PubMed Central

Tien, Nguyen T.; Karaca, Ilker; Tamboli, Irfan Y.

2016-01-01

The disaccharide trehalose is commonly considered to stimulate autophagy. Cell treatment with trehalose could decrease cytosolic aggregates of potentially pathogenic proteins, including mutant huntingtin, α-synuclein, and phosphorylated tau that are associated with neurodegenerative diseases. Here, we demonstrate that trehalose also alters the metabolism of the Alzheimer disease-related amyloid precursor protein (APP). Cell treatment with trehalose decreased the degradation of full-length APP and its C-terminal fragments. Trehalose also reduced the secretion of the amyloid-β peptide. Biochemical and cell biological experiments revealed that trehalose alters the subcellular distribution and decreases the degradation of APP C-terminal fragments in endolysosomal compartments. Trehalose also led to strong accumulation of the autophagic marker proteins LC3-II and p62, and decreased the proteolytic activation of the lysosomal hydrolase cathepsin D. The combined data indicate that trehalose decreases the lysosomal metabolism of APP by altering its endocytic vesicular transport. PMID:26957541

Three-dimensional Organization of Layered Apical Cytoskeletal Networks Associated with Mouse Airway Tissue Development

NASA Astrophysics Data System (ADS)

Tateishi, Kazuhiro; Nishida, Tomoki; Inoue, Kanako; Tsukita, Sachiko

2017-03-01

The cytoskeleton is an essential cellular component that enables various sophisticated functions of epithelial cells by forming specialized subcellular compartments. However, the functional and structural roles of cytoskeletons in subcellular compartmentalization are still not fully understood. Here we identified a novel network structure consisting of actin filaments, intermediate filaments, and microtubules directly beneath the apical membrane in mouse airway multiciliated cells and in cultured epithelial cells. Three-dimensional imaging by ultra-high voltage electron microscopy and immunofluorescence revealed that the morphological features of each network depended on the cell type and were spatiotemporally integrated in association with tissue development. Detailed analyses using Odf2 mutant mice, which lack ciliary basal feet and apical microtubules, suggested a novel contribution of the intermediate filaments to coordinated ciliary beating. These findings provide a new perspective for viewing epithelial cell differentiation and tissue morphogenesis through the structure and function of apical cytoskeletal networks.

Targeted Degradation of Proteins Localized in Subcellular Compartments by Hybrid Small Molecules.

PubMed

Okuhira, Keiichiro; Shoda, Takuji; Omura, Risa; Ohoka, Nobumichi; Hattori, Takayuki; Shibata, Norihito; Demizu, Yosuke; Sugihara, Ryo; Ichino, Asato; Kawahara, Haruka; Itoh, Yukihiro; Ishikawa, Minoru; Hashimoto, Yuichi; Kurihara, Masaaki; Itoh, Susumu; Saito, Hiroyuki; Naito, Mikihiko

2017-03-01

Development of novel small molecules that selectively degrade pathogenic proteins would provide an important advance in targeted therapy. Recently, we have devised a series of hybrid small molecules named SNIPER (specific and nongenetic IAP-dependent protein ERaser) that induces the degradation of target proteins via the ubiquitin-proteasome system. To understand the localization of proteins that can be targeted by this protein knockdown technology, we examined whether SNIPER molecules are able to induce degradation of cellular retinoic acid binding protein II (CRABP-II) proteins localized in subcellular compartments of cells. CRABP-II is genetically fused with subcellular localization signals, and they are expressed in the cells. SNIPER(CRABP) with different IAP-ligands, SNIPER(CRABP)-4 with bestatin and SNIPER(CRABP)-11 with MV1 compound, induce the proteasomal degradation of wild-type (WT), cytosolic, nuclear, and membrane-localized CRABP-II proteins, whereas only SNIPER(CRABP)-11 displayed degradation activity toward the mitochondrial CRABP-II protein. The small interfering RNA-mediated silencing of cIAP1 expression attenuated the knockdown activity of SNIPER(CRABP) against WT and cytosolic CRABP-II proteins, indicating that cIAP1 is the E3 ligase responsible for degradation of these proteins. Against membrane-localized CRABP-II protein, cIAP1 is also a primary E3 ligase in the cells, but another E3 ligase distinct from cIAP2 and X-linked inhibitor of apoptosis protein (XIAP) could also be involved in the SNIPER(CRABP)-11-induced degradation. However, for the degradation of nuclear and mitochondrial CRABP-II proteins, E3 ligases other than cIAP1, cIAP2, and XIAP play a role in the SNIPER-mediated protein knockdown. These results indicate that SNIPER can target cytosolic, nuclear, membrane-localized, and mitochondrial proteins for degradation, but the responsible E3 ligase is different, depending on the localization of the target protein. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

Subcellular localization and expression pattern of the neurofibromatosis type 2 protein merlin/schwannomin.

PubMed

Schmucker, B; Ballhausen, W G; Kressel, M

1997-01-01

To elucidate the physiological function of the neurofibromatosis type 2 (NF2) tumor suppressor protein merlin/schwannomin, we studied the expression pattern and subcellular localization in human fibroblasts by Western blot analyses and immunofluorescence using a polyclonal antibody raised against the C-terminus of merlin. Three of the six merlin isoforms identified in this study (75 kDa, 58 kDa, 45 kDa) have been reported earlier and can be explained by alternative splicing. In addition, we detected higher molecular weight bands of about 110 kDa, 100 kDa and 84 kDa. Although the merlin bands of 100 kDa and 110 kDa may represent homo- or heterodimers, oligomerization due to formation of disulfide bonds was excluded. Furthermore, the isoforms of 84 kDa and 58 kDa were quantitatively extractable in Lubrol WX, indicating a localization in or close to the plasma membrane. The 45 kDa band, however, was not soluble in Lubrol WX compatible with a localization of this NF2 isoform in the endoplasmic reticulum. Applying confocal laser scanning microscopy, merlin was shown to be located in four subcellular compartments: (i) perinuclear in a compartment resembling endoplasmic reticulum, (ii) in ruffling membranes and at the leading edges, (iii) in filopodia, and (iv) at cell/substrate adhesion points. Codistribution of merlin and F-actin filaments was found in filopodia, ruffling membranes and at the insertion points of stress fibers at cell/substrate adhesion junctions as shown by phalloidin-rhodamine staining. Double immunofluorescence analyses of merlin and moesin revealed a colocalization in filopodia and ruffling membranes. The localization of merlin in the actin-rich cortical cytoskeleton corresponds to the ezrin-radixin-moesin family of proteins suggesting the NF2 protein to contribute to the regulation of cell growth by interaction with cytoskeleton-associated proteins.

Subcellular distribution of trace elements and liver histology of landlocked Arctic char (Salvelinus alpinus) sampled along a mercury contamination gradient.

PubMed

Barst, Benjamin D; Rosabal, Maikel; Campbell, Peter G C; Muir, Derek G C; Wang, Xioawa; Köck, Günter; Drevnick, Paul E

2016-05-01

We sampled landlocked Arctic char (Salvelinus alpinus) from four lakes (Small, 9-Mile, North, Amituk) in the Canadian High Arctic that span a gradient of mercury contamination. Metals (Hg, Se, Tl, and Fe) were measured in char tissues to determine their relationships with health indices (relative condition factor and hepatosomatic index), stable nitrogen isotope ratios, and liver histology. A subcellular partitioning procedure was employed to determine how metals were distributed between potentially sensitive and detoxified compartments of Arctic char livers from a low- and high-mercury lake (Small Lake and Amituk Lake, respectively). Differences in health indices and metal concentrations among char populations were likely related to differences in feeding ecology. Concentrations of Hg, Se, and Tl were highest in the livers of Amituk char, whereas concentrations of Fe were highest in Small and 9-Mile char. At the subcellular level we found that although Amituk char had higher concentrations of Tl in whole liver than Small Lake char, they maintained a greater proportion of this metal in detoxified fractions, suggesting an attempt at detoxification. Mercury was found mainly in potentially sensitive fractions of both Small and Amituk Lake char, indicating that Arctic char are not effectively detoxifying this metal. Histological changes in char livers, mainly in the form of melano-macrophage aggregates and hepatic fibrosis, could be linked to the concentrations and subcellular distributions of essential or non-essential metals. Copyright © 2016 Elsevier Ltd. All rights reserved.

The src-family protein-tyrosine kinase p59hck is located on the secretory granules in human neutrophils and translocates towards the phagosome during cell activation.

PubMed Central

Möhn, H; Le Cabec, V; Fischer, S; Maridonneau-Parini, I

1995-01-01

The src-family protein-tyrosine kinase p59hck is mainly expressed in neutrophils; however, its functional role in these cells is unknown. Several other src-family members are localized on secretory vesicles and have been proposed to regulate intracellular traffic. We have established here the subcellular localization of p59hck in human neutrophils. Immunoblotting of subcellular fractions showed that approx. 60% of the p59hck per cell is localized on the secretory granules; the other 40% is distributed equally between non-granular membranes and the cytosol. Immunofluorescence of neutrophils and HL60 cells suggests that the p59hck-positive granules are azurophil granules. Granular p59hck is highly susceptible to degradation by an azurophil-granule proteinase. Different forms of p59hck occur in the three subcellular compartments: a 61 kDa form is mainly found in the granules, a 59 kDa form is predominant in the non-granular membranes, whereas cytosolic p59hck migrates as a doublet at 63 kDa. During the process of phagocytosis-linked degranulation, induced by serum-opsonized zymosan in neutrophils or HL60 cells, granular p59hck translocates towards the phagosome. The subcellular localization of p59hck suggests that the enzyme could be involved in the regulation of the degranulation process. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:7626033

Extraction protocol and liquid chromatography/tandem mass spectrometry method for determining micelle-entrapped paclitaxel at the cellular and subcellular levels: Application to a cellular uptake and distribution study.

PubMed

Zheng, Nan; Lian, Bin; Du, Wenwen; Xu, Guobing; Ji, Jiafu

2018-01-01

Paclitaxel-loaded polymeric micelles (PTX-PM) are commonly used as tumor-targeted nanocarriers and display outstanding antitumor features in clinic, but its accumulation and distribution in vitro are lack of investigation. It is probably due to the complex micellar system and its low concentration at the cellular or subcellular levels. In this study, we developed an improved extraction method, which was a combination of mechanical disruption and liquid-liquid extraction (LLE), to extract the total PTX from micelles in the cell lysate and subcellular compartments. An ultra-performance liquid chromatography tandem mass spectroscopy (UPLC-MS/MS) method was optimized to detect the low concentration of PTX at cellular and subcellular levels simultaneously, using docetaxel as internal standard (IS). The method was proved to release PTX totally from micelles (≥95.93%) with a consistent and reproducible extraction recovery (≥75.04%). Good linearity was obtained at concentrations ranging from 0.2 to 20ng/mL. The relative error (RE%) for accuracy varied from 0.68 to 7.56%, and the intra- and inter-precision (relative standard deviation, RSD%) was less than 8.64% and 13.14%, respectively. This method was fully validated and successfully applied to the cellular uptake and distribution study of PTX-loaded PLGA-PEG micelles in human breast cancer cells (MCF-7). Copyright © 2017 Elsevier B.V. All rights reserved.

pLoc-mPlant: predict subcellular localization of multi-location plant proteins by incorporating the optimal GO information into general PseAAC.

PubMed

Cheng, Xiang; Xiao, Xuan; Chou, Kuo-Chen

2017-08-22

One of the fundamental goals in cellular biochemistry is to identify the functions of proteins in the context of compartments that organize them in the cellular environment. To realize this, it is indispensable to develop an automated method for fast and accurate identification of the subcellular locations of uncharacterized proteins. The current study is focused on plant protein subcellular location prediction based on the sequence information alone. Although considerable efforts have been made in this regard, the problem is far from being solved yet. Most of the existing methods can be used to deal with single-location proteins only. Actually, proteins with multi-locations may have some special biological functions. This kind of multiplex protein is particularly important for both basic research and drug design. Using the multi-label theory, we present a new predictor called "pLoc-mPlant" by extracting the optimal GO (Gene Ontology) information into the Chou's general PseAAC (Pseudo Amino Acid Composition). Rigorous cross-validation on the same stringent benchmark dataset indicated that the proposed pLoc-mPlant predictor is remarkably superior to iLoc-Plant, the state-of-the-art method for predicting plant protein subcellular localization. To maximize the convenience of most experimental scientists, a user-friendly web-server for the new predictor has been established at , by which users can easily get their desired results without the need to go through the complicated mathematics involved.

Spatiotemporal Monitoring of Pseudomonas syringae Effectors via Type III Secretion Using Split Fluorescent Protein Fragments[OPEN

PubMed Central

2017-01-01

Pathogenic gram-negative bacteria cause serious diseases in animals and plants. These bacterial pathogens use the type III secretion system (T3SS) to deliver effector proteins into host cells; these effectors then localize to different subcellular compartments to attenuate immune responses by altering biological processes of the host cells. The fluorescent protein (FP)-based approach to monitor effectors secreted from bacteria into the host cells is not possible because the folded FP prevents effector delivery through the T3SS. Therefore, we optimized an improved variant of self-assembling split super-folder green fluorescent protein (sfGFPOPT) system to investigate the spatiotemporal dynamics of effectors delivered through bacterial T3SS into plant cells. In this system, effectors are fused to 11th β-strand of super-folder GFP (sfGFP11), and when delivered into plant cells expressing sfGFP1-10 β-strand (sfGFP1-10OPT), the two proteins reconstitute GFP fluorescence. We generated a number of Arabidopsis thaliana transgenic lines expressing sfGFP1-10OPT targeted to various subcellular compartments to facilitate localization of sfGFP11-tagged effectors delivered from bacteria. We demonstrate the efficacy of this system using Pseudomonas syringae effectors AvrB and AvrRps4 in Nicotiana benthamiana and transgenic Arabidopsis plants. The versatile split sfGFPOPT system described here will facilitate a better understanding of bacterial invasion strategies used to evade plant immune responses. PMID:28619883

Stochastic theory of large-scale enzyme-reaction networks: Finite copy number corrections to rate equation models

NASA Astrophysics Data System (ADS)

Thomas, Philipp; Straube, Arthur V.; Grima, Ramon

2010-11-01

Chemical reactions inside cells occur in compartment volumes in the range of atto- to femtoliters. Physiological concentrations realized in such small volumes imply low copy numbers of interacting molecules with the consequence of considerable fluctuations in the concentrations. In contrast, rate equation models are based on the implicit assumption of infinitely large numbers of interacting molecules, or equivalently, that reactions occur in infinite volumes at constant macroscopic concentrations. In this article we compute the finite-volume corrections (or equivalently the finite copy number corrections) to the solutions of the rate equations for chemical reaction networks composed of arbitrarily large numbers of enzyme-catalyzed reactions which are confined inside a small subcellular compartment. This is achieved by applying a mesoscopic version of the quasisteady-state assumption to the exact Fokker-Planck equation associated with the Poisson representation of the chemical master equation. The procedure yields impressively simple and compact expressions for the finite-volume corrections. We prove that the predictions of the rate equations will always underestimate the actual steady-state substrate concentrations for an enzyme-reaction network confined in a small volume. In particular we show that the finite-volume corrections increase with decreasing subcellular volume, decreasing Michaelis-Menten constants, and increasing enzyme saturation. The magnitude of the corrections depends sensitively on the topology of the network. The predictions of the theory are shown to be in excellent agreement with stochastic simulations for two types of networks typically associated with protein methylation and metabolism.

A Compartmentalized Mathematical Model of the β1-Adrenergic Signaling System in Mouse Ventricular Myocytes

PubMed Central

Bondarenko, Vladimir E.

2014-01-01

The β1-adrenergic signaling system plays an important role in the functioning of cardiac cells. Experimental data shows that the activation of this system produces inotropy, lusitropy, and chronotropy in the heart, such as increased magnitude and relaxation rates of [Ca2+]i transients and contraction force, and increased heart rhythm. However, excessive stimulation of β1-adrenergic receptors leads to heart dysfunction and heart failure. In this paper, a comprehensive, experimentally based mathematical model of the β1-adrenergic signaling system for mouse ventricular myocytes is developed, which includes major subcellular functional compartments (caveolae, extracaveolae, and cytosol). The model describes biochemical reactions that occur during stimulation of β1-adrenoceptors, changes in ionic currents, and modifications of Ca2+ handling system. Simulations describe the dynamics of major signaling molecules, such as cyclic AMP and protein kinase A, in different subcellular compartments; the effects of inhibition of phosphodiesterases on cAMP production; kinetics and magnitudes of phosphorylation of ion channels, transporters, and Ca2+ handling proteins; modifications of action potential shape and duration; magnitudes and relaxation rates of [Ca2+]i transients; changes in intracellular and transmembrane Ca2+ fluxes; and [Na+]i fluxes and dynamics. The model elucidates complex interactions of ionic currents upon activation of β1-adrenoceptors at different stimulation frequencies, which ultimately lead to a relatively modest increase in action potential duration and significant increase in [Ca2+]i transients. In particular, the model includes two subpopulations of the L-type Ca2+ channels, in caveolae and extracaveolae compartments, and their effects on the action potential and [Ca2+]i transients are investigated. The presented model can be used by researchers for the interpretation of experimental data and for the developments of mathematical models for other species or for pathological conditions. PMID:24586529

N-Glycomic and Microscopic Subcellular Localization Analyses of NPP1, 2 and 6 Strongly Indicate that trans-Golgi Compartments Participate in the Golgi to Plastid Traffic of Nucleotide Pyrophosphatase/Phosphodiesterases in Rice

PubMed Central

Kaneko, Kentaro; Takamatsu, Takeshi; Inomata, Takuya; Oikawa, Kazusato; Itoh, Kimiko; Hirose, Kazuko; Amano, Maho; Nishimura, Shin-Ichiro; Toyooka, Kiminori; Matsuoka, Ken; Pozueta-Romero, Javier; Mitsui, Toshiaki

2016-01-01

Nucleotide pyrophosphatase/phosphodiesterases (NPPs) are widely distributed N-glycosylated enzymes that catalyze the hydrolytic breakdown of numerous nucleotides and nucleotide sugars. In many plant species, NPPs are encoded by a small multigene family, which in rice are referred to NPP1–NPP6. Although recent investigations showed that N-glycosylated NPP1 is transported from the endoplasmic reticulum (ER)–Golgi system to the chloroplast through the secretory pathway in rice cells, information on N-glycan composition and subcellular localization of other NPPs is still lacking. Computer-assisted analyses of the amino acid sequences deduced from different Oryza sativa NPP-encoding cDNAs predicted all NPPs to be secretory glycoproteins. Confocal fluorescence microscopy observation of cells expressing NPP2 and NPP6 fused with green fluorescent protein (GFP) revealed that NPP2 and NPP6 are plastidial proteins. Plastid targeting of NPP2–GFP and NPP6–GFP was prevented by brefeldin A and by the expression of ARF1(Q71L), a dominant negative mutant of ADP-ribosylation factor 1 that arrests the ER to Golgi traffic, indicating that NPP2 and NPP6 are transported from the ER–Golgi to the plastidial compartment. Confocal laser scanning microscopy and high-pressure frozen/freeze-substituted electron microscopy analyses of transgenic rice cells ectopically expressing the trans-Golgi marker sialyltransferase fused with GFP showed the occurrence of contact of Golgi-derived membrane vesicles with cargo and subsequent absorption into plastids. Sensitive and high-throughput glycoblotting/mass spectrometric analyses showed that complex-type and paucimannosidic-type glycans with fucose and xylose residues occupy approximately 80% of total glycans of NPP1, NPP2 and NPP6. The overall data strongly indicate that the trans-Golgi compartments participate in the Golgi to plastid trafficking and targeting mechanism of NPPs. PMID:27335351

A Variable Polyglutamine Repeat Affects Subcellular Localization and Regulatory Activity of a Populus ANGUSTIFOLIA Protein.

PubMed

Bryan, Anthony C; Zhang, Jin; Guo, Jianjun; Ranjan, Priya; Singan, Vasanth; Barry, Kerrie; Schmutz, Jeremy; Weighill, Deborah; Jacobson, Daniel; Jawdy, Sara; Tuskan, Gerald A; Chen, Jin-Gui; Muchero, Wellington

2018-06-08

Polyglutamine (polyQ) stretches have been reported to occur in proteins across many organisms including animals, fungi and plants. Expansion of these repeats has attracted much attention due their associations with numerous human diseases including Huntington's and other neurological maladies. This suggests that the relative length of polyQ stretches is an important modulator of their function. Here, we report the identification of a Populus C-terminus binding protein (CtBP) ANGUSTIFOLIA ( PtAN1 ) which contains a polyQ stretch whose functional relevance had not been established. Analysis of 917 resequenced Populus trichocarpa genotypes revealed three allelic variants at this locus encoding 11-, 13- and 15-glutamine residues. Transient expression assays using Populus leaf mesophyll protoplasts revealed that the 11Q variant exhibited strong nuclear localization whereas the 15Q variant was only found in the cytosol, with the 13Q variant exhibiting localization in both subcellular compartments. We assessed functional implications by evaluating expression changes of putative PtAN1 targets in response to overexpression of the three allelic variants and observed allele-specific differences in expression levels of putative targets. Our results provide evidence that variation in polyQ length modulates PtAN1 function by altering subcellular localization. Copyright © 2018, G3: Genes, Genomes, Genetics.

Nuclear Cytoplasmic Trafficking of Proteins is a Major Response of Human Fibroblasts to Oxidative Stress

PubMed Central

Baqader, Noor O.; Radulovic, Marko; Crawford, Mark; Stoeber, Kai; Godovac-Zimmermann, Jasminka

2014-01-01

We have used a subcellular spatial razor approach based on LC–MS/MS-based proteomics with SILAC isotope labeling to determine changes in protein abundances in the nuclear and cytoplasmic compartments of human IMR90 fibroblasts subjected to mild oxidative stress. We show that response to mild tert-butyl hydrogen peroxide treatment includes redistribution between the nucleus and cytoplasm of numerous proteins not previously associated with oxidative stress. The 121 proteins with the most significant changes encompass proteins with known functions in a wide variety of subcellular locations and of cellular functional processes (transcription, signal transduction, autophagy, iron metabolism, TCA cycle, ATP synthesis) and are consistent with functional networks that are spatially dispersed across the cell. Both nuclear respiratory factor 2 and the proline regulatory axis appear to contribute to the cellular metabolic response. Proteins involved in iron metabolism or with iron/heme as a cofactor as well as mitochondrial proteins are prominent in the response. Evidence suggesting that nuclear import/export and vesicle-mediated protein transport contribute to the cellular response was obtained. We suggest that measurements of global changes in total cellular protein abundances need to be complemented with measurements of the dynamic subcellular spatial redistribution of proteins to obtain comprehensive pictures of cellular function. PMID:25133973

46 CFR 174.075 - Compartments assumed flooded: general.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Compartments assumed flooded: general. 174.075 Section 174.075 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling...

46 CFR 174.075 - Compartments assumed flooded: general.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Compartments assumed flooded: general. 174.075 Section 174.075 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling...

Trafficking-deficient hERG K+ channels linked to long QT syndrome are regulated by a microtubule-dependent quality control compartment in the ER

PubMed Central

Smith, Jennifer L.; McBride, Christie M.; Nataraj, Parvathi S.; Bartos, Daniel C.; January, Craig T.

2011-01-01

The human ether-a-go-go related gene (hERG) encodes the voltage-gated K+ channel that underlies the rapidly activating delayed-rectifier current in cardiac myocytes. hERG is synthesized in the endoplasmic reticulum (ER) as an “immature” N-linked glycoprotein and is terminally glycosylated in the Golgi apparatus. Most hERG missense mutations linked to long QT syndrome type 2 (LQT2) reduce the terminal glycosylation and functional expression. We tested the hypothesis that a distinct pre-Golgi compartment negatively regulates the trafficking of some LQT2 mutations to the Golgi apparatus. We found that treating cells in nocodazole, a microtubule depolymerizing agent, altered the subcellular localization, functional expression, and glycosylation of the LQT2 mutation G601S-hERG differently from wild-type hERG (WT-hERG). G601S-hERG quickly redistributed to peripheral compartments that partially colocalized with KDEL (Lys-Asp-Glu-Leu) chaperones but not calnexin, Sec31, or the ER golgi intermediate compartment (ERGIC). Treating cells in E-4031, a drug that increases the functional expression of G601S-hERG, prevented the accumulation of G601S-hERG to the peripheral compartments and increased G601S-hERG colocalization with the ERGIC. Coexpressing the temperature-sensitive mutant G protein from vesicular stomatitis virus, a mutant N-linked glycoprotein that is retained in the ER, showed it was not restricted to the same peripheral compartments as G601S-hERG at nonpermissive temperatures. We conclude that the trafficking of G601S-hERG is negatively regulated by a microtubule-dependent compartment within the ER. Identifying mechanisms that prevent the sorting or promote the release of LQT2 channels from this compartment may represent a novel therapeutic strategy for LQT2. PMID:21490315

14 CFR 382.125 - What procedures do carriers follow when wheelchairs, other mobility aids, and other assistive...

Code of Federal Regulations, 2012 CFR

2012-01-01

... wheelchairs, other mobility aids, and other assistive devices must be stowed in the cargo compartment? 382.125... Wheelchairs, Other Mobility Aids, and Other Assistive Devices § 382.125 What procedures do carriers follow when wheelchairs, other mobility aids, and other assistive devices must be stowed in the cargo...

14 CFR 382.125 - What procedures do carriers follow when wheelchairs, other mobility aids, and other assistive...

Code of Federal Regulations, 2013 CFR

2013-01-01

... wheelchairs, other mobility aids, and other assistive devices must be stowed in the cargo compartment? 382.125... Wheelchairs, Other Mobility Aids, and Other Assistive Devices § 382.125 What procedures do carriers follow when wheelchairs, other mobility aids, and other assistive devices must be stowed in the cargo...

14 CFR 382.125 - What procedures do carriers follow when wheelchairs, other mobility aids, and other assistive...

Code of Federal Regulations, 2014 CFR

2014-01-01

... wheelchairs, other mobility aids, and other assistive devices must be stowed in the cargo compartment? 382.125... Wheelchairs, Other Mobility Aids, and Other Assistive Devices § 382.125 What procedures do carriers follow when wheelchairs, other mobility aids, and other assistive devices must be stowed in the cargo...

A maize database resource that captures tissue-specific and subcellular-localized gene expression, via fluorescent tags and confocal imaging (Maize Cell Genomics Database).

PubMed

Krishnakumar, Vivek; Choi, Yongwook; Beck, Erin; Wu, Qingyu; Luo, Anding; Sylvester, Anne; Jackson, David; Chan, Agnes P

2015-01-01

Maize is a global crop and a powerful system among grain crops for genetic and genomic studies. However, the development of novel biological tools and resources to aid in the functional identification of gene sequences is greatly needed. Towards this goal, we have developed a collection of maize marker lines for studying native gene expression in specific cell types and subcellular compartments using fluorescent proteins (FPs). To catalog FP expression, we have developed a public repository, the Maize Cell Genomics (MCG) Database, (http://maize.jcvi.org/cellgenomics), to organize a large data set of confocal images generated from the maize marker lines. To date, the collection represents major subcellular structures and also developmentally important progenitor cell populations. The resource is available to the research community, for example to study protein localization or interactions under various experimental conditions or mutant backgrounds. A subset of the marker lines can also be used to induce misexpression of target genes through a transactivation system. For future directions, the image repository can be expanded to accept new image submissions from the research community, and to perform customized large-scale computational image analysis. This community resource will provide a suite of new tools for gaining biological insights by following the dynamics of protein expression at the subcellular, cellular and tissue levels. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Off to the Organelles - Killing Cancer Cells with Targeted Gold Nanoparticles

PubMed Central

Kodiha, Mohamed; Wang, Yi Meng; Hutter, Eliza; Maysinger, Dusica; Stochaj, Ursula

2015-01-01

Gold nanoparticles (AuNPs) are excellent tools for cancer cell imaging and basic research. However, they have yet to reach their full potential in the clinic. At present, we are only beginning to understand the molecular mechanisms that underlie the biological effects of AuNPs, including the structural and functional changes of cancer cells. This knowledge is critical for two aspects of nanomedicine. First, it will define the AuNP-induced events at the subcellular and molecular level, thereby possibly identifying new targets for cancer treatment. Second, it could provide new strategies to improve AuNP-dependent cancer diagnosis and treatment. Our review summarizes the impact of AuNPs on selected subcellular organelles that are relevant to cancer therapy. We focus on the nucleus, its subcompartments, and mitochondria, because they are intimately linked to cancer cell survival, growth, proliferation and death. While non-targeted AuNPs can damage tumor cells, concentrating AuNPs in particular subcellular locations will likely improve tumor cell killing. Thus, it will increase cancer cell damage by photothermal ablation, mechanical injury or localized drug delivery. This concept is promising, but AuNPs have to overcome multiple hurdles to perform these tasks. AuNP size, morphology and surface modification are critical parameters for their delivery to organelles. Recent strategies explored all of these variables, and surface functionalization has become crucial to concentrate AuNPs in subcellular compartments. Here, we highlight the use of AuNPs to damage cancer cells and their organelles. We discuss current limitations of AuNP-based cancer research and conclude with future directions for AuNP-dependent cancer treatment. PMID:25699096

Subcellular investigation of photosynthesis-driven carbon assimilation in the symbiotic reef coral Pocillopora damicornis.

PubMed

Kopp, Christophe; Domart-Coulon, Isabelle; Escrig, Stephane; Humbel, Bruno M; Hignette, Michel; Meibom, Anders

2015-02-10

Reef-building corals form essential, mutualistic endosymbiotic associations with photosynthetic Symbiodinium dinoflagellates, providing their animal host partner with photosynthetically derived nutrients that allow the coral to thrive in oligotrophic waters. However, little is known about the dynamics of these nutritional interactions at the (sub)cellular level. Here, we visualize with submicrometer spatial resolution the carbon and nitrogen fluxes in the intact coral-dinoflagellate association from the reef coral Pocillopora damicornis by combining nanoscale secondary ion mass spectrometry (NanoSIMS) and transmission electron microscopy with pulse-chase isotopic labeling using [(13)C]bicarbonate and [(15)N]nitrate. This allows us to observe that (i) through light-driven photosynthesis, dinoflagellates rapidly assimilate inorganic bicarbonate and nitrate, temporarily storing carbon within lipid droplets and starch granules for remobilization in nighttime, along with carbon and nitrogen incorporation into other subcellular compartments for dinoflagellate growth and maintenance, (ii) carbon-containing photosynthates are translocated to all four coral tissue layers, where they accumulate after only 15 min in coral lipid droplets from the oral gastroderm and within 6 h in glycogen granules from the oral epiderm, and (iii) the translocation of nitrogen-containing photosynthates is delayed by 3 h. Our results provide detailed in situ subcellular visualization of the fate of photosynthesis-derived carbon and nitrogen in the coral-dinoflagellate endosymbiosis. We directly demonstrate that lipid droplets and glycogen granules in the coral tissue are sinks for translocated carbon photosynthates by dinoflagellates and confirm their key role in the trophic interactions within the coral-dinoflagellate association. Copyright © 2015 Kopp et al.

Switching from a unicellular to multicellular organization in an Aspergillus niger hypha.

PubMed

Bleichrodt, Robert-Jan; Hulsman, Marc; Wösten, Han A B; Reinders, Marcel J T

2015-03-03

Pores in fungal septa enable cytoplasmic streaming between hyphae and their compartments. Consequently, the mycelium can be considered unicellular. However, we show here that Woronin bodies close ~50% of the three most apical septa of growing hyphae of Aspergillus niger. The incidence of closure of the 9th and 10th septa was even ≥94%. Intercompartmental streaming of photoactivatable green fluorescent protein (PA-GFP) was not observed when the septa were closed, but open septa acted as a barrier, reducing the mobility rate of PA-GFP ~500 times. This mobility rate decreased with increasing septal age and under stress conditions, likely reflecting a regulatory mechanism affecting septal pore diameter. Modeling revealed that such regulation offers effective control of compound concentration between compartments. Modeling also showed that the incidence of septal closure in A. niger had an even stronger impact on cytoplasmic continuity. Cytoplasm of hyphal compartments was shown not to be in physical contact when separated by more than 4 septa. Together, data show that apical compartments of growing hyphae behave unicellularly, while older compartments have a multicellular organization. The hyphae of higher fungi are compartmentalized by porous septa that enable cytosolic streaming. Therefore, it is believed that the mycelium shares cytoplasm. However, it is shown here that the septa of Aspergillus niger are always closed in the oldest part of the hyphae, and therefore, these compartments are physically isolated from each other. In contrast, only part of the septa is closed in the youngest part of the hyphae. Still, compartments in this hyphal part are physically isolated when separated by more than 4 septa. Even open septa act as a barrier for cytoplasmic mixing. The mobility rate through such septa reduces with increasing septal age and under stress conditions. Modeling shows that the septal pore width is set such that its regulation offers maximal control of compound concentration levels within the compartments. Together, we show for the first time that Aspergillus hyphae switch from a unicellular to multicellular organization. Copyright © 2015 Bleichrodt et al.

Insulin-Responsive Compartments Containing GLUT4 in 3T3-L1 and CHO Cells: Regulation by Amino Acid Concentrations

PubMed Central

Bogan, Jonathan S.; McKee, Adrienne E.; Lodish, Harvey F.

2001-01-01

In fat and muscle, insulin stimulates glucose uptake by rapidly mobilizing the GLUT4 glucose transporter from a specialized intracellular compartment to the plasma membrane. We describe a method to quantify the relative proportion of GLUT4 at the plasma membrane, using flow cytometry to measure a ratio of fluorescence intensities corresponding to the cell surface and total amounts of a tagged GLUT4 reporter in individual living cells. Using this assay, we demonstrate that both 3T3-L1 and CHO cells contain intracellular compartments from which GLUT4 is rapidly mobilized by insulin and that the initial magnitude and kinetics of redistribution to the plasma membrane are similar in these two cell types when they are cultured identically. Targeting of GLUT4 to a highly insulin-responsive compartment in CHO cells is modulated by culture conditions. In particular, we find that amino acids regulate distribution of GLUT4 to this kinetically defined compartment through a rapamycin-sensitive pathway. Amino acids also modulate the magnitude of insulin-stimulated translocation in 3T3-L1 adipocytes. Our results indicate a novel link between glucose and amino acid metabolism. PMID:11416153

Discriminative motif discovery via simulated evolution and random under-sampling.

PubMed

Song, Tao; Gu, Hong

2014-01-01

Conserved motifs in biological sequences are closely related to their structure and functions. Recently, discriminative motif discovery methods have attracted more and more attention. However, little attention has been devoted to the data imbalance problem, which is one of the main reasons affecting the performance of the discriminative models. In this article, a simulated evolution method is applied to solve the multi-class imbalance problem at the stage of data preprocessing, and at the stage of Hidden Markov Models (HMMs) training, a random under-sampling method is introduced for the imbalance between the positive and negative datasets. It is shown that, in the task of discovering targeting motifs of nine subcellular compartments, the motifs found by our method are more conserved than the methods without considering data imbalance problem and recover the most known targeting motifs from Minimotif Miner and InterPro. Meanwhile, we use the found motifs to predict protein subcellular localization and achieve higher prediction precision and recall for the minority classes.

Trehalose Alters Subcellular Trafficking and the Metabolism of the Alzheimer-associated Amyloid Precursor Protein.

PubMed

Tien, Nguyen T; Karaca, Ilker; Tamboli, Irfan Y; Walter, Jochen

2016-05-13

The disaccharide trehalose is commonly considered to stimulate autophagy. Cell treatment with trehalose could decrease cytosolic aggregates of potentially pathogenic proteins, including mutant huntingtin, α-synuclein, and phosphorylated tau that are associated with neurodegenerative diseases. Here, we demonstrate that trehalose also alters the metabolism of the Alzheimer disease-related amyloid precursor protein (APP). Cell treatment with trehalose decreased the degradation of full-length APP and its C-terminal fragments. Trehalose also reduced the secretion of the amyloid-β peptide. Biochemical and cell biological experiments revealed that trehalose alters the subcellular distribution and decreases the degradation of APP C-terminal fragments in endolysosomal compartments. Trehalose also led to strong accumulation of the autophagic marker proteins LC3-II and p62, and decreased the proteolytic activation of the lysosomal hydrolase cathepsin D. The combined data indicate that trehalose decreases the lysosomal metabolism of APP by altering its endocytic vesicular transport. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Detection of focal adhesion kinase activation at membrane microdomains by fluorescence resonance energy transfer.

PubMed

Seong, Jihye; Ouyang, Mingxing; Kim, Taejin; Sun, Jie; Wen, Po-Chao; Lu, Shaoying; Zhuo, Yue; Llewellyn, Nicholas M; Schlaepfer, David D; Guan, Jun-Lin; Chien, Shu; Wang, Yingxiao

2011-07-26

Proper subcellular localization of focal adhesion kinase (FAK) is crucial for many cellular processes. It remains, however, unclear how FAK activity is regulated at subcellular compartments. To visualize the FAK activity at different membrane microdomains, we develop a fluorescence resonance energy transfer (FRET)-based FAK biosensor, and target it into or outside of detergent-resistant membrane (DRM) regions at the plasma membrane. Here we show that, on cell adhesion to extracellular matrix proteins or stimulation by platelet-derived growth factor (PDGF), the FRET responses of DRM-targeting FAK biosensor are stronger than that at non-DRM regions, suggesting that FAK activation can occur at DRM microdomains. Further experiments reveal that the PDGF-induced FAK activation is mediated and maintained by Src activity, whereas FAK activation on cell adhesion is independent of, and in fact essential for the Src activation. Therefore, FAK is activated at membrane microdomains with distinct activation mechanisms in response to different physiological stimuli. © 2011 Macmillan Publishers Limited. All rights reserved.

Adipocyte aminopeptidases in obesity and fasting.

PubMed

Alponti, Rafaela Fadoni; Silveira, Paulo Flavio

2015-11-05

This study checked the existence of a diverse array of aminopeptidase (AP) enzymes in high (HDM) and low (LDM) density microsomal and plasma membrane (MF) fractions from adipocytes of control, monosodium glutamate obese and food deprived rats. Gene expression was detected for ArgAP, AspAP, MetAP, and two AlaAP (APM and PSA). APM and PSA had the highest catalytic efficiency, whereas AspAP the highest affinity. Subcellular distribution of AP activities depended on metabolic status. Comparing catalytic levels, AspAP in HDM, LDM and MF was absent in obese and control under food deprivation; PSA in LDM was 3.5-times higher in obese than in normally fed control and control and obese under food deprivation; MetAP in MF was 4.5-times higher in obese than in food deprived obese. Data show new AP enzymes genetically expressed in subcellular compartments of adipocytes, three of them with altered catalytic levels that respond to whole-body energetic demands. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Subcellular distribution of an inhalational anesthetic in situ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eckenhoff, R.G.; Shuman, H.

1990-01-01

To better understand the mechanisms and sites of anesthetic action, we determined the subcellular partitioning of halothane in a tissue model. A method was found to fix the in vivo distribution of halothane in rat atrial tissue for subsequent electron microscopy and x-ray microanalysis. Atrial strips were exposed to various concentrations of halothane, rapidly frozen, cryo-sectioned, and cryo-transferred into an electron microscope. Irradiation of the hydrated cryosections with the electron beam caused halothane radiolysis, which allowed retention of the halogen-containing fragments after dehydration of the sections. The bromine from halothane was detected and quantified with x-ray microanalysis in various microregionsmore » of atrial myocytes. Halothane (bromine) partitioned largely to mitochondria, with progressively lower concentrations in sarcolemma, nuclear membrane, cytoplasm, sarcomere, and nucleus. Partitioning could not be explained solely by distribution of cellular lipid, suggesting significant and differential physicochemical solubility in protein. However, we found no saturable compartment in atrial myocytes within the clinical concentration range, which implies little specific protein binding.« less

The role of endomembrane-localized VHA-c in plant growth.

PubMed

Zhou, Aimin; Takano, Tetsuo; Liu, Shenkui

2018-01-02

In plant cells, the vacuolar-type H + -ATPase (V-ATPase), a large multis`ubunit endomembrane proton pump, plays an important role in acidification of subcellular organelles, pH and ion homeostasis, and endocytic and secretory trafficking. V-ATPase subunit c (VHA-c) is essential for V-ATPase assembly, and is directly responsible for binding and transmembrane transport of protons. In previous studies, we identified a PutVHA-c gene from Puccinellia tenuiflora, and investigated its function in plant growth. Subcellular localization revealed that PutVHA-c is mainly localized in endosomal compartments. Overexpression of PutVHA-c enhanced V-ATPase activity and promoted plant growth in transgenic Arabidopsis. Furthermore, the activity of V-ATPase affected intracellular transport of the Golgi-derived endosomes. Our results showed that endomembrane localized-VHA-c contributes to plant growth by influencing V-ATPase-dependent endosomal trafficking. Here, we discuss these recent findings and speculate on the VHA-c mediated molecular mechanisms involved in plant growth, providing a better understanding of the functions of VHA-c and V-ATPase.

In vivo ROS and redox potential fluorescent detection in plants: Present approaches and future perspectives.

PubMed

Ortega-Villasante, Cristina; Burén, Stefan; Barón-Sola, Ángel; Martínez, Flor; Hernández, Luis E

2016-10-15

Reactive oxygen species (ROS) are metabolic by-products in aerobic organisms including plants. Endogenously produced ROS act as cellular messengers and redox regulators involved in several plant biological processes, but excessive accumulation of ROS cause oxidative stress and cell damage. Understanding ROS signalling and stress responses requires precise imaging and quantification of local, subcellular and global ROS dynamics with high selectivity, sensitivity, and spatiotemporal resolution. Several fluorescent vital dyes have been tested so far, which helped to provide relevant spatially resolved information of oxidative stress dynamics in plants subjected to harmful environmental conditions. However, certain plant characteristics, such as high background fluorescence of plant tissues in vivo and antioxidant mechanisms, can interfere with ROS detection. The development of improved small-molecule fluorescent dyes and protein-based ROS sensors targeted to subcellular compartments will enable in vivo monitoring of ROS and redox changes in photosynthetic organisms. Copyright © 2016 Elsevier Inc. All rights reserved.

ABCD2 identifies a subclass of peroxisomes in mouse adipose tissue

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xiaoxi, E-mail: xiaoxi.liu@uky.edu; Liu, Jingjing, E-mail: jingjing.liu0@gmail.com; Lester, Joshua D., E-mail: joshua.lester@uky.edu

2015-01-02

Highlights: • We examined the D2 localization and the proteome of D2-containing compartment in mouse adipose tissue. • We confirmed the presence of D2 on a subcellular compartment that has typical structure as a microperoxisome. • We demonstrated the scarcity of peroxisome markers on D2-containing compartment. • The D2-containing compartment may be a subpopulation of peroxisome in mouse adipose tissue. • Proteomic data suggests potential association between D2-containing compartment and mitochondria and ER. - Abstract: ATP-binding cassette transporter D2 (D2) is an ABC half transporter that is thought to promote the transport of very long-chain fatty acyl-CoAs into peroxisomes. Bothmore » D2 and peroxisomes increase during adipogenesis. Although peroxisomes are essential to both catabolic and anabolic lipid metabolism, their function, and that of D2, in adipose tissues remain largely unknown. Here, we investigated the D2 localization and the proteome of D2-containing organelles, in adipose tissue. Centrifugation of mouse adipose homogenates generated a fraction enriched with D2, but deficient in peroxisome markers including catalase, PEX19, and ABCD3 (D3). Electron microscopic imaging of this fraction confirmed the presence of D2 protein on an organelle with a dense matrix and a diameter of ∼200 nm, the typical structure and size of a microperoxisome. D2 and PEX19 antibodies recognized distinct structures in mouse adipose. Immunoisolation of the D2-containing compartment confirmed the scarcity of PEX19 and proteomic profiling revealed the presence of proteins associated with peroxisome, endoplasmic reticulum (ER), and mitochondria. D2 is localized to a distinct class of peroxisomes that lack many peroxisome proteins, and may associate physically with mitochondria and the ER.« less

Comparative Characterization of Phosphatidic Acid Sensors and Their Localization during Frustrated Phagocytosis.

PubMed

Kassas, Nawal; Tanguy, Emeline; Thahouly, Tamou; Fouillen, Laetitia; Heintz, Dimitri; Chasserot-Golaz, Sylvette; Bader, Marie-France; Grant, Nancy J; Vitale, Nicolas

2017-03-10

Phosphatidic acid (PA) is the simplest phospholipid naturally existing in living organisms, but it constitutes only a minor fraction of total cell lipids. PA has attracted considerable attention because it is a phospholipid precursor, a lipid second messenger, and a modulator of membrane shape, and it has thus been proposed to play key cellular functions. The dynamics of PA in cells and in subcellular compartments, however, remains an open question. The recent generation of fluorescent probes for PA, by fusing GFP to PA-binding domains, has provided direct evidence for PA dynamics in different intracellular compartments. Here, three PA sensors were characterized in vitro, and their preferences for different PA species in particular lipidic environments were compared. In addition, the localization of PA in macrophages during frustrated phagocytosis was examined using these PA sensors and was combined with a lipidomic analysis of PA in intracellular compartments. The results indicate that the PA sensors display some preferences for specific PA species, depending on the lipid environment, and the localization study in macrophages revealed the complexity of intracellular PA dynamics. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Virus-PLoc: a fusion classifier for predicting the subcellular localization of viral proteins within host and virus-infected cells.

PubMed

Shen, Hong-Bin; Chou, Kuo-Chen

2007-02-15

Viruses can reproduce their progenies only within a host cell, and their actions depend both on its destructive tendencies toward a specific host cell and on environmental conditions. Therefore, knowledge of the subcellular localization of viral proteins in a host cell or virus-infected cell is very useful for in-depth studying of their functions and mechanisms as well as designing antiviral drugs. An analysis on the Swiss-Prot database (version 50.0, released on May 30, 2006) indicates that only 23.5% of viral protein entries are annotated for their subcellular locations in this regard. As for the gene ontology database, the corresponding percentage is 23.8%. Such a gap calls for the development of high throughput tools for timely annotating the localization of viral proteins within host and virus-infected cells. In this article, a predictor called "Virus-PLoc" has been developed that is featured by fusing many basic classifiers with each engineered according to the K-nearest neighbor rule. The overall jackknife success rate obtained by Virus-PLoc in identifying the subcellular compartments of viral proteins was 80% for a benchmark dataset in which none of proteins has more than 25% sequence identity to any other in a same location site. Virus-PLoc will be freely available as a web-server at http://202.120.37.186/bioinf/virus for the public usage. Furthermore, Virus-PLoc has been used to provide large-scale predictions of all viral protein entries in Swiss-Prot database that do not have subcellular location annotations or are annotated as being uncertain. The results thus obtained have been deposited in a downloadable file prepared with Microsoft Excel and named "Tab_Virus-PLoc.xls." This file is available at the same website and will be updated twice a year to include the new entries of viral proteins and reflect the continuous development of Virus-PLoc. 2006 Wiley Periodicals, Inc.

Proteome-wide Subcellular Topologies of E. coli Polypeptides Database (STEPdb)*

PubMed Central

Orfanoudaki, Georgia; Economou, Anastassios

2014-01-01

Cell compartmentalization serves both the isolation and the specialization of cell functions. After synthesis in the cytoplasm, over a third of all proteins are targeted to other subcellular compartments. Knowing how proteins are distributed within the cell and how they interact is a prerequisite for understanding it as a whole. Surface and secreted proteins are important pathogenicity determinants. Here we present the STEP database (STEPdb) that contains a comprehensive characterization of subcellular localization and topology of the complete proteome of Escherichia coli. Two widely used E. coli proteomes (K-12 and BL21) are presented organized into thirteen subcellular classes. STEPdb exploits the wealth of genetic, proteomic, biochemical, and functional information on protein localization, secretion, and targeting in E. coli, one of the best understood model organisms. Subcellular annotations were derived from a combination of bioinformatics prediction, proteomic, biochemical, functional, topological data and extensive literature re-examination that were refined through manual curation. Strong experimental support for the location of 1553 out of 4303 proteins was based on 426 articles and some experimental indications for another 526. Annotations were provided for another 320 proteins based on firm bioinformatic predictions. STEPdb is the first database that contains an extensive set of peripheral IM proteins (PIM proteins) and includes their graphical visualization into complexes, cellular functions, and interactions. It also summarizes all currently known protein export machineries of E. coli K-12 and pairs them, where available, with the secretory proteins that use them. It catalogs the Sec- and TAT-utilizing secretomes and summarizes their topological features such as signal peptides and transmembrane regions, transmembrane topologies and orientations. It also catalogs physicochemical and structural features that influence topology such as abundance, solubility, disorder, heat resistance, and structural domain families. Finally, STEPdb incorporates prediction tools for topology (TMHMM, SignalP, and Phobius) and disorder (IUPred) and implements the BLAST2STEP that performs protein homology searches against the STEPdb. PMID:25210196

Distribution and Function of HCN Channels in the Apical Dendritic Tuft of Neocortical Pyramidal Neurons

PubMed Central

Harnett, Mark T.; Magee, Jeffrey C.

2015-01-01

The apical tuft is the most remote area of the dendritic tree of neocortical pyramidal neurons. Despite its distal location, the apical dendritic tuft of layer 5 pyramidal neurons receives substantial excitatory synaptic drive and actively processes corticocortical input during behavior. The properties of the voltage-activated ion channels that regulate synaptic integration in tuft dendrites have, however, not been thoroughly investigated. Here, we use electrophysiological and optical approaches to examine the subcellular distribution and function of hyperpolarization-activated cyclic nucleotide-gated nonselective cation (HCN) channels in rat layer 5B pyramidal neurons. Outside-out patch recordings demonstrated that the amplitude and properties of ensemble HCN channel activity were uniform in patches excised from distal apical dendritic trunk and tuft sites. Simultaneous apical dendritic tuft and trunk whole-cell current-clamp recordings revealed that the pharmacological blockade of HCN channels decreased voltage compartmentalization and enhanced the generation and spread of apical dendritic tuft and trunk regenerative activity. Furthermore, multisite two-photon glutamate uncaging demonstrated that HCN channels control the amplitude and duration of synaptically evoked regenerative activity in the distal apical dendritic tuft. In contrast, at proximal apical dendritic trunk and somatic recording sites, the blockade of HCN channels decreased excitability. Dynamic-clamp experiments revealed that these compartment-specific actions of HCN channels were heavily influenced by the local and distributed impact of the high density of HCN channels in the distal apical dendritic arbor. The properties and subcellular distribution pattern of HCN channels are therefore tuned to regulate the interaction between integration compartments in layer 5B pyramidal neurons. PMID:25609619

Localization and Functionality of the Inflammasome in Neutrophils*

PubMed Central

Bakele, Martina; Joos, Melanie; Burdi, Sofia; Allgaier, Nicolas; Pöschel, Simone; Fehrenbacher, Birgit; Schaller, Martin; Marcos, Veronica; Kümmerle-Deschner, Jasmin; Rieber, Nikolaus; Borregaard, Niels; Yazdi, Amir; Hector, Andreas; Hartl, Dominik

2014-01-01

Neutrophils represent the major fraction of circulating immune cells and are rapidly recruited to sites of infection and inflammation. The inflammasome is a multiprotein complex that regulates the generation of IL-1 family proteins. The precise subcellular localization and functionality of the inflammasome in human neutrophils are poorly defined. Here we demonstrate that highly purified human neutrophils express key components of the NOD-like receptor family, pyrin domain containing 3 (NLRP3), and absent in melanoma 2 (AIM2) inflammasomes, particularly apoptosis-associated speck-like protein containing a CARD (ASC), AIM2, and caspase-1. Subcellular fractionation and microscopic analyses further showed that inflammasome components were localized in the cytoplasm and also noncanonically in secretory vesicle and tertiary granule compartments. Whereas IL-1β and IL-18 were expressed at the mRNA level and released as protein, highly purified neutrophils neither expressed nor released IL-1α at baseline or upon stimulation. Upon inflammasome activation, highly purified neutrophils released substantially lower levels of IL-1β protein compared with partially purified neutrophils. Serine proteases and caspases were differentially involved in IL-1β release, depending on the stimulus. Spontaneous activation of the NLRP3 inflammasome in neutrophils in vivo affected IL-1β, but not IL-18 release. In summary, these studies show that human neutrophils express key components of the inflammasome machinery in distinct intracellular compartments and release IL-1β and IL-18, but not IL-1α or IL-33 protein. Targeting the neutrophil inflammasome may represent a future therapeutic strategy to modulate neutrophilic inflammatory diseases, such as cystic fibrosis, rheumatoid arthritis, or sepsis. PMID:24398679

Intracellular processing of poly(ethylene imine)/ribozyme complexes can be observed in living cells by using confocal laser scanning microscopy and inhibitor experiments.

PubMed

Merdan, Thomas; Kunath, Klaus; Fischer, Dagmar; Kopecek, Jindrich; Kissel, Thomas

2002-02-01

Critical steps in the subcellular processing of poly(ethylene imine)/nucleic acid complexes, especially endosomal/lysosomal escape, were visualized by using living cell confocal laser scanning microscopy (CSLM) to obtain an insight into their mechanism. Living cell confocal microscopy was used to examine the intracellular fate of poly(ethylene imine)/ribozyme and poly(L-lysine)/ribozyme complexes over time, in the presence of and without bafilomycin Al, a selective inhibitor of endosomal/lysosomal acidification. The compartment of complex accumulation was identified by confocal microscopy with a fluorescent acidotropic dye. To confirm microscopic data, luciferase reporter gene expression was determined under similar experimental conditions. Poly(ethylene imine)/ribozyme complexes accumulate in acidic vesicles, most probably lysosomes. Release of complexes occurs in a sudden event, very likely due to bursting of these organelles. After release, poly(ethylene imine) and ribozyme spread throughout the cell, during which slight differences in distribution between cytosol and nucleus are visible. No lysosomal escape was observed with poly(L-lysine)/ribozyme complexes or when poly(ethylene imine)/ ribozyme complexes were applied together with bafilomycin A1. Poly(ethylene imine)/plasmid complexes exhibited a high luciferase expression, which was reduced approximately 200-fold when lysosomal acidification was suppressed with bafilomycin A1. Our data provide, for the first time, direct experimental evidence for the escape of poly(ethylene imine)/nucleic acid complexes from the endosomal/lysosomal compartment. CLSM, in conjunction with living cell microscopy, is a promising tool for studying the subcellular fate of polyplexes in nucleic acid/gene delivery.

14 CFR 382.127 - What procedures apply to stowage of battery-powered mobility aids?

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false What procedures apply to stowage of battery... What procedures apply to stowage of battery-powered mobility aids? (a) Whenever baggage compartment... a passenger's battery-powered wheelchair or other similar mobility device, including the battery, as...

14 CFR 382.127 - What procedures apply to stowage of battery-powered mobility aids?

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false What procedures apply to stowage of battery... What procedures apply to stowage of battery-powered mobility aids? (a) Whenever baggage compartment... a passenger's battery-powered wheelchair or other similar mobility device, including the battery, as...

14 CFR 382.127 - What procedures apply to stowage of battery-powered mobility aids?

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false What procedures apply to stowage of battery... What procedures apply to stowage of battery-powered mobility aids? (a) Whenever baggage compartment... a passenger's battery-powered wheelchair or other similar mobility device, including the battery, as...

14 CFR 382.127 - What procedures apply to stowage of battery-powered mobility aids?

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false What procedures apply to stowage of battery... What procedures apply to stowage of battery-powered mobility aids? (a) Whenever baggage compartment... a passenger's battery-powered wheelchair or other similar mobility device, including the battery, as...

14 CFR 382.127 - What procedures apply to stowage of battery-powered mobility aids?

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false What procedures apply to stowage of battery... What procedures apply to stowage of battery-powered mobility aids? (a) Whenever baggage compartment... a passenger's battery-powered wheelchair or other similar mobility device, including the battery, as...

Real-time quantification of subcellular H2O2 and glutathione redox potential in living cardiovascular tissues.

PubMed

Panieri, Emiliano; Millia, Carlo; Santoro, Massimo M

2017-08-01

Detecting and measuring the dynamic redox events that occur in vivo is a prerequisite for understanding the impact of oxidants and redox events in normal and pathological conditions. These aspects are particularly relevant in cardiovascular tissues wherein alterations of the redox balance are associated with stroke, aging, and pharmacological intervention. An ambiguous aspect of redox biology is how redox events occur in subcellular organelles including mitochondria, and nuclei. Genetically-encoded Rogfp2 fluorescent probes have become powerful tools for real-time detection of redox events. These probes detect hydrogen peroxide (H 2 O 2 ) levels and glutathione redox potential (E GSH ), both with high spatiotemporal resolution. By generating novel transgenic (Tg) zebrafish lines that express compartment-specific Rogfp2-Orp1 and Grx1-Rogfp2 sensors we analyzed cytosolic, mitochondrial, and the nuclear redox state of endothelial cells and cardiomyocytes of living zebrafish embryos. We provide evidence for the usefulness of these Tg lines for pharmacological compounds screening by addressing the blocking of pentose phosphate pathways (PPP) and glutathione synthesis, thus altering subcellular redox state in vivo. Rogfp2-based transgenic zebrafish lines represent valuable tools to characterize the impact of redox changes in living tissues and offer new opportunities for studying metabolic driven antioxidant response in biomedical research. Copyright © 2017 Elsevier Inc. All rights reserved.

A novel mechanism of E2F1 regulation via nucleocytoplasmic shuttling: determinants of nuclear import and export.

PubMed

Ivanova, Iordanka A; Vespa, Alisa; Dagnino, Lina

2007-09-01

E2F1 is a transcription factor central for cell survival, proliferation, and repair following genomic insult. Depending on the cell type and conditions, E2F1 can induce apoptosis in transformed cells, behaving as a tumour suppressor, or impart growth advantages favouring tumour formation. The pleiotropic functions of E2F1 are a likely consequence of its ability to transcriptionally control a wide variety of target genes, and require tight regulation of its activity at multiple levels. Although sequestration of proteins to particular cellular compartments is a well-established regulatory mechanism, virtually nothing is known about its contribution to modulation of E2F1 target gene expression. We have examined the subcellular trafficking of E2F1 and, contrary to the widely held notion that this factor is constitutively nuclear, we now demonstrate that it is subjected to continuous nucleocytoplasmic shuttling. We have also defined two nuclear localization domains and a nuclear export region, which mediates CRM1-dependent transit out of the nucleus. The predominant subcellular location of E2F1 is likely determined by the balance between the activity of nuclear import and export domains, and can be modulated by differentiation stimuli in epidermal cells. Thus, we have identified a hitherto unrecognized mechanism to control E2F1 function through modulation of its subcellular localization.

Treatment of a case of subacute lumbar compartment syndrome using the Graston technique.

PubMed

Hammer, Warren I; Pfefer, Mark T

2005-01-01

To discuss subacute lumbar compartment syndrome and its treatment using a soft tissue mobilization technique. A patient presented with low back pain related to exercise combined with prolonged flexion posture. The symptoms were relieved with rest and lumbar extension. The patient had restrictive lumbar fascia in flexion and rotation and no neurological deficits. The restrictive lumbar posterior fascial layers and adjoining restrictive fascia (thoracic, gluteal, hamstring) were treated with a form of instrument-assisted soft tissue mobilization called the Graston technique. Restoration of fascial extensibility and resolution of the complaint occurred after 6 treatment visits. The posterior spinal fascial compartments may be responsible for intermittent lower back pain. Functional clinical tests can be employed to determine whether the involved fascia is abnormally restrictive. Treatment directed at the restrictive fascia using this soft tissue technique may result in improved fascial functional testing and reduction of symptoms.

Metabolic Interplay between Peroxisomes and Other Subcellular Organelles Including Mitochondria and the Endoplasmic Reticulum

PubMed Central

Wanders, Ronald J. A.; Waterham, Hans R.; Ferdinandusse, Sacha

2016-01-01

Peroxisomes are unique subcellular organelles which play an indispensable role in several key metabolic pathways which include: (1.) etherphospholipid biosynthesis; (2.) fatty acid beta-oxidation; (3.) bile acid synthesis; (4.) docosahexaenoic acid (DHA) synthesis; (5.) fatty acid alpha-oxidation; (6.) glyoxylate metabolism; (7.) amino acid degradation, and (8.) ROS/RNS metabolism. The importance of peroxisomes for human health and development is exemplified by the existence of a large number of inborn errors of peroxisome metabolism in which there is an impairment in one or more of the metabolic functions of peroxisomes. Although the clinical signs and symptoms of affected patients differ depending upon the enzyme which is deficient and the extent of the deficiency, the disorders involved are usually (very) severe diseases with neurological dysfunction and early death in many of them. With respect to the role of peroxisomes in metabolism it is clear that peroxisomes are dependent on the functional interplay with other subcellular organelles to sustain their role in metabolism. Indeed, whereas mitochondria can oxidize fatty acids all the way to CO2 and H2O, peroxisomes are only able to chain-shorten fatty acids and the end products of peroxisomal beta-oxidation need to be shuttled to mitochondria for full oxidation to CO2 and H2O. Furthermore, NADH is generated during beta-oxidation in peroxisomes and beta-oxidation can only continue if peroxisomes are equipped with a mechanism to reoxidize NADH back to NAD+, which is now known to be mediated by specific NAD(H)-redox shuttles. In this paper we describe the current state of knowledge about the functional interplay between peroxisomes and other subcellular compartments notably the mitochondria and endoplasmic reticulum for each of the metabolic pathways in which peroxisomes are involved. PMID:26858947

Fundamental studies of adrenal retinoid-X-receptor: Protein isoform, tissue expression, subcellular distribution, and ligand availability.

PubMed

Cheng, Behling; Al-Shammari, Fatema H; Ghader, Isra'a A; Sequeira, Fatima; Thakkar, Jitendra; Mathew, Thazhumpal C

2017-07-01

Adrenal gland reportedly expresses many nuclear receptors that are known to heterodimerize with retinoid-X-receptor (RXR) for functions, but the information regarding the glandular RXR is not adequate. Studies of rat adrenal homogenate by Western blotting revealed three RXR proteins: RXRα (55kDa), RXRβ (47kDa) and RXR (56kDa). RXRγ was not detectable. After fractionation, RXRα was almost exclusively localized in the nuclear fraction. In comparison, substantial portions of RXRβ and RXR were found in both nuclear and post-nuclear particle fractions, suggesting genomic and non-genomic functions. Cells immunostained for RXRα were primarily localized in zona fasciculata (ZF) and medulla, although some stained cells were found in zona glomerulosa (ZG) and zona reticularis (ZR). In contrast, cells immunostained for RXRβ were concentrated principally in ZG, although some stained cells were seen in ZR, ZF, and medulla (in descending order, qualitatively). Analysis of adrenal lipid extracts by LC/MS did not detect 9-cis-retinoic acid (a potent RXR-ligand) but identified all-trans retinoic acid. Since C20 and C22 polyunsaturated fatty acids (PUFAs) can also activate RXR, subcellular availabilities of unesterified fatty acids were investigated by GC/MS. As results, arachidonic acid (C20:4), adrenic acid (C22:4), docosapentaenoic acid (C22:5), and cervonic acid (C22:6) were detected in the lipids extracted from each subcellular fraction. Thus, the RXR-agonizing PUFAs are available in all the main subcellular compartments considerably. The present findings not only shed light on the adrenal network of RXRs but also provide baseline information for further investigations of RXR heterodimers in the regulation of adrenal steroidogenesis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Met receptor inhibitor SU11274 localizes in the endoplasmic reticulum.

PubMed

Wiest, Edwin J; Smith, Heather Jensen; Hollingsworth, Michael A

2018-07-02

We discovered that SU11274, a class I c-Met inhibitor, fluoresces when excited by 488 nm laser light and showed rapid specific accumulation in distinct subcellular compartments. Given that SU11274 reduces cancer cell viability, we exploited these newly identified spectral properties to determine SU11274 intracellular distribution and accumulation in human pancreatic cancer cells. The aim of the studies reported here was to identify organelle(s) to which SU11274 is trafficked. We conclude that SU11274 rapidly and predominantly accumulates in the endoplasmic reticulum. Copyright © 2018. Published by Elsevier Inc.

Proteomics profiling of interactome dynamics by colocalisation analysis (COLA).

PubMed

Mardakheh, Faraz K; Sailem, Heba Z; Kümper, Sandra; Tape, Christopher J; McCully, Ryan R; Paul, Angela; Anjomani-Virmouni, Sara; Jørgensen, Claus; Poulogiannis, George; Marshall, Christopher J; Bakal, Chris

2016-12-20

Localisation and protein function are intimately linked in eukaryotes, as proteins are localised to specific compartments where they come into proximity of other functionally relevant proteins. Significant co-localisation of two proteins can therefore be indicative of their functional association. We here present COLA, a proteomics based strategy coupled with a bioinformatics framework to detect protein-protein co-localisations on a global scale. COLA reveals functional interactions by matching proteins with significant similarity in their subcellular localisation signatures. The rapid nature of COLA allows mapping of interactome dynamics across different conditions or treatments with high precision.

Chemotherapy Enhances Cross-Presentation of Nuclear Tumor Antigens

PubMed Central

Anyaegbu, Chidozie C.; Lake, Richard A.; Heel, Kathy; Robinson, Bruce W.; Fisher, Scott A.

2014-01-01

Cross-presentation of tumor antigen is essential for efficient priming of naïve CD8+ T lymphocytes and induction of effective anti-tumor immunity. We hypothesized that the subcellular location of a tumor antigen could affect the efficiency of cross-presentation, and hence the outcome of anti-tumor responses to that antigen. We compared cross-presentation of a nominal antigen expressed in the nuclear, secretory, or cytoplasmic compartments of B16 melanoma tumors. All tumors expressed similar levels of the antigen. The antigen was cross-presented from all compartments but when the concentration was low, nuclear antigen was less efficiently cross-presented than antigen from other cellular locations. The efficiency of cross-presentation of the nuclear antigen was improved following chemotherapy-induced tumor cell apoptosis and this correlated with an increase in the proportion of effector CTL. These data demonstrate that chemotherapy improves nuclear tumor antigen cross-presentation and could be important for anti-cancer immunotherapies that target nuclear antigens. PMID:25243472

The two-pore channel TPC1 is required for efficient protein processing through early and recycling endosomes.

PubMed

Castonguay, Jan; Orth, Joachim H C; Müller, Thomas; Sleman, Faten; Grimm, Christian; Wahl-Schott, Christian; Biel, Martin; Mallmann, Robert Theodor; Bildl, Wolfgang; Schulte, Uwe; Klugbauer, Norbert

2017-08-30

Two-pore channels (TPCs) are localized in endo-lysosomal compartments and assumed to play an important role for vesicular fusion and endosomal trafficking. Recently, it has been shown that both TPC1 and 2 were required for host cell entry and pathogenicity of Ebola viruses. Here, we investigate the cellular function of TPC1 using protein toxins as model substrates for distinct endosomal processing routes. Toxin uptake and activation through early endosomes but not processing through other compartments were reduced in TPC1 knockout cells. Detailed co-localization studies with subcellular markers confirmed predominant localization of TPC1 to early and recycling endosomes. Proteomic analysis of native TPC1 channels finally identified direct interaction with a distinct set of syntaxins involved in fusion of intracellular vesicles. Together, our results demonstrate a general role of TPC1 for uptake and processing of proteins in early and recycling endosomes, likely by providing high local Ca 2+ concentrations required for SNARE-mediated vesicle fusion.

Isolated adrenal cells: adrenocorticotropic hormone, calcium, steroidogenesis, and cyclic adenosine monophosphate.

PubMed

Sayers, G; Beall, R J; Seelig, S

1972-03-10

Corticosterone production by isolated adrenal cells in response to adrenocorticotropic hormone is reduced when the cells are incubated in a medium that contains no calcium. This reduction is associated with an equal reduction of accumulation of cyclic adenosine monophosphate. Production of corticosterone and accumulation of cyclic adenosine monophosphate are increased when the calcium concentration in the medium is increased (from zero to 7.65 millimolar). This is in contrast to the situation in "subcellular membrane fragments" of adrenal tissue where high calcium in the medium (> 1.0 millimolar) inhibits cyclic adenosine monophosphate accumulation. We propose that adenyl cyclase in the intact plasma membrane is located in a compartment wherein calcium concentration is low and remains unaffected by the concentration of calcium in the extracellular space. It is proposed that, as the concentration of calcium in the incubation medium is increased from zero to 7.65 millimolar, the strength of the signal generated by the interaction of adrenocorticotropic hormone with its receptor and transmitted to the adenyl cyclase compartment is proportionately increased.

PrPc Does Not Mediate Internalization of PrPSc but Is Required at an Early Stage for De Novo Prion Infection of Rov Cells▿

PubMed Central

Paquet, Sophie; Daude, Nathalie; Courageot, Marie-Pierre; Chapuis, Jérôme; Laude, Hubert; Vilette, Didier

2007-01-01

We have studied the interactions of exogenous prions with an epithelial cell line inducibly expressing PrPc protein and permissive to infection by a sheep scrapie agent. We demonstrate that abnormal PrP (PrPSc) and prion infectivity are efficiently internalized in Rov cells, whether or not PrPc is expressed. At odds with earlier studies implicating cellular heparan sulfates in PrPSc internalization, we failed to find any involvement of such molecules in Rov cells, indicating that prions can enter target cells by several routes. We further show that PrPSc taken up in the absence of PrPc was unable to promote efficient prion multiplication once PrPc expression was restored in the cells. This observation argues that interaction of PrPSc with PrPc has to occur early, in a specific subcellular compartment(s), and is consistent with the view that the first prion multiplication events may occur at the cell surface. PMID:17626095

Quantifying immunogold labelling patterns of cellular compartments when they comprise mixtures of membranes (surface-occupying) and organelles (volume-occupying).

PubMed

Mayhew, Terry M; Lucocq, John M

2008-03-01

In quantitative immunoelectron microscopy, subcellular compartments that are preferentially labelled with colloidal gold particles can be identified by estimating labelling densities (LDs) and relative labelling indices (RLIs). Hitherto, this approach has been limited to compartments which are either surface occupying (membranes) or volume occupying (organelles) but not a mixture of both (membranes and organelles). However, some antigens are known to translocate between membrane and organelle compartments and the problem then arises of expressing gold particle LDs in a consistent manner (e.g., as number per compartment profile area). Here, we present one possible solution to tackle this problem. With this method, each membrane is treated as a volume-occupying compartment and this is achieved by creating an acceptance zone at a fixed distance on each side of membrane images. Gold signal intensity is then expressed as an LD within the membrane profile area so created and this LD can be compared to LDs found in volume-occupying compartments. Acceptance zone width is determined largely by the expected dispersion of gold labelling. In some cases, the zone can be applied to all visible membrane images but there is a potential problem when image loss occurs due to the fact that membranes are not cut orthogonal to their surface but are tilted within the section. The solution presented here is to select a subset of clear images representing orthogonally sectioned membranes (so-called local vertical windows, LVWs). The fraction of membrane images forming LVWs can be estimated in two ways: goniometrically (by determining the angle at which images become unclear) or stereologically (by counting intersections with test lines). The fraction obtained by either method can then be used to calculate a factor correcting for membrane image loss. In turn, this factor is used to estimate the total gold labelling associated with the acceptance zone of the entire (volume-occupying) membrane. However calculated, the LDs over the chosen (membrane and organelle) compartments are used to obtain observed and expected gold particle counts. The observed distribution is determined simply by counting gold particles associated with each compartment. Next, an expected distribution is created by randomly superimposing test points and counting those hitting each compartment. LDs of the chosen compartments are used to calculate RLI and chi-squared values and these serve to identify those compartments in which there is preferential labelling. The methods are illustrated by synthetic and real data.

Pharmacological AMP-kinase activators have compartment-specific effects on cell physiology.

PubMed

Kodiha, Mohamed; Ho-Wo-Cheong, Dennis; Stochaj, Ursula

2011-12-01

5'-AMP-activated kinase (AMPK) regulates numerous biological events and is an essential target for the treatment of type 2 diabetes. The objectives of the present study were first to determine the compartment-specific effects of three established AMPK activators on Thr172 phosphorylation of the α-subunit, an indicator of AMPK activation. Second, we examined how cytoplasmic and nuclear processes are modulated by pharmacological AMPK activators. Specifically, the impact of phenformin, resveratrol, and 5-aminoimidazole-4-carboxamide riboside (AICAR) on Thr172 phosphorylation in the cytoplasm and nucleus was quantified by different methods. To analyze how these activators change cell physiology, we measured the inactivation of acetyl-CoA-carboxylase 1, a predominantly cytoplasmic enzyme that is crucial for lipid metabolism. As a criterion for activities associated with the nucleus, de novo RNA synthesis in nucleoli was quantified. Our studies demonstrate that pharmacological activators of AMPK can alter the balance between nuclear and cytoplasmic AMPK pools. Thus, phenformin and resveratrol caused a strong activation of AMPK in the cytoplasm, whereas the effect was less pronounced in nuclei. By contrast, AICAR elicited a comparable rise in Thr172 phosphorylation in both compartments. Notably, these activators differed drastically in their effects on physiological processes that are located in distinct subcellular compartments. All compounds led to a substantial inactivation of acetyl-CoA-carboxylase 1 in the cytoplasm, with only minor changes to the nuclear enzyme. In the nucleolus, transcription was strongly inhibited by resveratrol, while a moderate inhibition was observed with phenformin and AICAR. Taken together, the compartment-specific phosphorylation of AMPK and downstream events are determined by the activator.

Registration procedure for spatial correlation of physical energy deposition of particle irradiation and cellular response utilizing cell-fluorescent ion track hybrid detectors

NASA Astrophysics Data System (ADS)

Niklas, M.; Zimmermann, F.; Schlegel, J.; Schwager, C.; Debus, J.; Jäkel, O.; Abdollahi, A.; Greilich, S.

2016-09-01

The hybrid technology cell-fluorescent ion track hybrid detector (Cell-Fit-HD) enables the investigation of radiation-related cellular events along single ion tracks on the subcellular scale in clinical ion beams. The Cell-Fit-HD comprises a fluorescent nuclear track detector (FNTD, the physical compartment), a device for individual particle detection and a substrate for viable cell-coating, i.e. the biological compartment. To date both compartments have been imaged sequentially in situ by confocal laser scanning microscopy (CLSM). This is yet in conflict with a functional read-out of the Cell-Fit-HD utilizing a fast live-cell imaging of the biological compartment with low phototoxicity on greater time scales. The read-out of the biological from the physical compartment was uncoupled. A read-out procedure was developed to image the cell layer by conventional widefield microscopy whereas the FNTD was imaged by CLSM. Point mapping registration of the confocal and widefield imaging data was performed. Non-fluorescent crystal defects (spinels) visible in both read-outs were used as control point pairs. The accuracy achieved was on the sub-µm scale. The read-out procedure by widefield microscopy does not impair the unique ability of spatial correlation by the Cell-Fit-HD. The uncoupling will enlarge the application potential of the hybrid technology significantly. The registration allows for an ultimate correlation of microscopic physical beam parameters and cell kinetics on greater time scales. The method reported herein will be instrumental for the introduction of a novel generation of compact detectors facilitating biodosimetric research towards high-throughput analysis.

New intracellular activities of matrix metalloproteinases shine in the moonlight.

PubMed

Jobin, Parker G; Butler, Georgina S; Overall, Christopher M

2017-11-01

Adaption of a single protein to perform multiple independent functions facilitates functional plasticity of the proteome allowing a limited number of protein-coding genes to perform a multitude of cellular processes. Multifunctionality is achievable by post-translational modifications and by modulating subcellular localization. Matrix metalloproteinases (MMPs), classically viewed as degraders of the extracellular matrix (ECM) responsible for matrix protein turnover, are more recently recognized as regulators of a range of extracellular bioactive molecules including chemokines, cytokines, and their binders. However, growing evidence has convincingly identified select MMPs in intracellular compartments with unexpected physiological and pathological roles. Intracellular MMPs have both proteolytic and non-proteolytic functions, including signal transduction and transcription factor activity thereby challenging their traditional designation as extracellular proteases. This review highlights current knowledge of subcellular location and activity of these "moonlighting" MMPs. Intracellular roles herald a new era of MMP research, rejuvenating interest in targeting these proteases in therapeutic strategies. This article is part of a Special Issue entitled: Matrix Metalloproteinases edited by Rafael Fridman. Copyright © 2017 Elsevier B.V. All rights reserved.

The role of lipids in host microbe interactions.

PubMed

Lang, Roland; Mattner, Jochen

2017-06-01

Lipids are one of the major subcellular constituents and serve as signal molecules, energy sources, metabolic precursors and structural membrane components in various organisms. The function of lipids can be modified by multiple biochemical processes such as (de-)phosphorylation or (de-)glycosylation, and the organization of fatty acids into distinct cellular pools and subcellular compartments plays a pivotal role for the morphology and function of various cell populations. Thus, lipids regulate, for example, phagosome formation and maturation within host cells and thus, are critical for the elimination of microbial pathogens. Vice versa, microbial pathogens can manipulate the lipid composition of phagosomal membranes in host cells, and thus avoid their delivery to phagolysosomes. Lipids of microbial origin belong also to the strongest and most versatile inducers of mammalian immune responses upon engagement of distinct receptors on myeloid and lymphoid cells. Furthermore, microbial lipid toxins can induce membrane injuries and cell death. Thus, we will review here selected examples for mutual host-microbe interactions within the broad and divergent universe of lipids in microbial defense, tissue injury and immune evasion.

Localization of arginine decarboxylase in tobacco plants.

PubMed

Bortolotti, Cristina; Cordeiro, Alexandra; Alcázar, Rubén; Borrell, Antoni; Culiañez-Macià, Francisco A.; Tiburcio, Antonio F.; Altabella, Teresa

2004-01-01

The lack of knowledge about the tissue and subcellular distribution of polyamines (PAs) and the enzymes involved in their metabolism remains one of the main obstacles in our understanding of the biological role of PAs in plants. Arginine decarboxylase (ADC; EC 4.1.1.9) is a key enzyme in polyamine biosynthesis in plants. We have characterized a cDNA coding for ADC from Nicotiana tabacum L. cv. Petit Havana SR1. The deduced ADC polypeptide had 721 amino acids and a molecular mass of 77 kDa. The ADC cDNA was overexpressed in Escherichia coli, and the ADC fusion protein obtained was used to produce polyclonal antibodies. Using immunological methods, we demonstrate the presence of the ADC protein in all plant organs analysed: flowers, seeds, stems, leaves and roots. Moreover, depending on the tissue, the protein is localized in two different subcellular compartments, the nucleus and the chloroplast. In photosynthetic tissues, ADC is located mainly in chloroplasts, whereas in non-photosynthetic tissues the protein appears to be located in nuclei. The different compartmentation of ADC may be related to distinct functions of the protein in different cell types.

Distribution and function of HCN channels in the apical dendritic tuft of neocortical pyramidal neurons.

PubMed

Harnett, Mark T; Magee, Jeffrey C; Williams, Stephen R

2015-01-21

The apical tuft is the most remote area of the dendritic tree of neocortical pyramidal neurons. Despite its distal location, the apical dendritic tuft of layer 5 pyramidal neurons receives substantial excitatory synaptic drive and actively processes corticocortical input during behavior. The properties of the voltage-activated ion channels that regulate synaptic integration in tuft dendrites have, however, not been thoroughly investigated. Here, we use electrophysiological and optical approaches to examine the subcellular distribution and function of hyperpolarization-activated cyclic nucleotide-gated nonselective cation (HCN) channels in rat layer 5B pyramidal neurons. Outside-out patch recordings demonstrated that the amplitude and properties of ensemble HCN channel activity were uniform in patches excised from distal apical dendritic trunk and tuft sites. Simultaneous apical dendritic tuft and trunk whole-cell current-clamp recordings revealed that the pharmacological blockade of HCN channels decreased voltage compartmentalization and enhanced the generation and spread of apical dendritic tuft and trunk regenerative activity. Furthermore, multisite two-photon glutamate uncaging demonstrated that HCN channels control the amplitude and duration of synaptically evoked regenerative activity in the distal apical dendritic tuft. In contrast, at proximal apical dendritic trunk and somatic recording sites, the blockade of HCN channels decreased excitability. Dynamic-clamp experiments revealed that these compartment-specific actions of HCN channels were heavily influenced by the local and distributed impact of the high density of HCN channels in the distal apical dendritic arbor. The properties and subcellular distribution pattern of HCN channels are therefore tuned to regulate the interaction between integration compartments in layer 5B pyramidal neurons. Copyright © 2015 the authors 0270-6474/15/351024-14$15.00/0.

Brain intracellular metabolites are freely diffusing along cell fibers in grey and white matter, as measured by diffusion-weighted MR spectroscopy in the human brain at 7 T.

PubMed

Najac, Chloé; Branzoli, Francesca; Ronen, Itamar; Valette, Julien

2016-04-01

Due to the specific compartmentation of brain metabolites, diffusion-weighted magnetic resonance spectroscopy opens unique insight into neuronal and astrocytic microstructures. The apparent diffusion coefficient (ADC) of brain metabolites depends on various intracellular parameters including cytosol viscosity and molecular crowding. When diffusion time (t d) is long enough, the size and geometry of the compartment in which the metabolites diffuse strongly influence metabolites ADC. In a previous study, performed in the macaque brain, we measured neuronal and astrocytic metabolites ADC at long t d (from 86 to 1,011 ms) in a large voxel enclosing an equal proportion of white and grey matter. We showed that metabolites apparently diffuse freely along the axis of dendrites, axons and astrocytic processes. To assess potential differences between these two tissue types, here we measured for the first time in the Human brain the t d-dependency of metabolites trace/3 ADC at 7 teslas using a localized diffusion-weighted STEAM sequence, in parietal and occipital voxels, respectively, containing mainly white and grey matter. We show that, in both tissues and over the observed timescale (t d varying from 92 to 712 ms) metabolite ADC reaches a non-zero plateau, suggesting that metabolites are not confined inside subcellular regions such as cell bodies, or inside subcellular compartments such as organelles, but are rather free to diffuse in the whole fiber-like structure of neurons and astrocytes. Beyond the fundamental insights into intracellular compartmentation of metabolites, this work also provides a new framework for interpreting results of neuroimaging techniques based on molecular diffusion, such as diffusion-weighted magnetic resonance spectroscopy and imaging.

Time-Lapse Monitoring of DNA Damage Colocalized With Particle Tracks in Single Living Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

McFadden, Conor H.; Hallacy, Timothy M.; Department of Physics and Astronomy, Rice University, Houston, Texas

2016-09-01

Purpose: Understanding the DNA damage and repair induced by hadron therapy (HT) beams is crucial for developing novel strategies to maximize the use of HT beams to treat cancer patients. However, spatiotemporal studies of DNA damage and repair for beam energies relevant to HT have been challenging. We report a technique that enables spatiotemporal measurement of radiation-induced damage in live cells and colocalization of this damage with charged particle tracks over a broad range of clinically relevant beam energies. The technique uses novel fluorescence nuclear track detectors with fluorescence confocal laser scanning microscopy in the beam line to visualize particlemore » track traversals within the subcellular compartments of live cells within seconds after injury. Methods and Materials: We designed and built a portable fluorescence confocal laser scanning microscope for use in the beam path, coated fluorescence nuclear track detectors with fluorescent-tagged live cells (HT1080 expressing enhanced green fluorescent protein tagged to XRCC1, a single-strand break repair protein), placed the entire assembly into a proton therapy beam line, and irradiated the cells with a fluence of ∼1 × 10{sup 6} protons/cm{sup 2}. Results: We successfully obtained confocal images of proton tracks and foci of DNA single-strand breaks immediately after irradiation. Conclusions: This technique represents an innovative method for analyzing biological responses in any HT beam line at energies and dose rates relevant to therapy. It allows precise determination of the number of tracks traversing a subcellular compartment and monitoring the cellular damage therein, and has the potential to measure the linear energy transfer of each track from therapeutic beams.« less

Brain intracellular metabolites are freely diffusing along cell fibers in grey and white matter, as measured by diffusion-weighted MR spectroscopy in the human brain at 7 T

PubMed Central

Najac, Chloé; Branzoli, Francesca; Ronen, Itamar; Valette, Julien

2016-01-01

Due to the specific compartmentation of brain metabolites, diffusion-weighted magnetic resonance spectroscopy opens unique insight into neuronal and astrocytic microstructures. The apparent diffusion coefficient (ADC) of brain metabolites depends on various intracellular parameters including cytosol viscosity and molecular crowding. When diffusion time (td) is long enough, the size and geometry of the compartment in which the metabolites diffuse strongly influence metabolites ADC. In a previous study, performed in the macaque brain, we measured neuronal and astrocytic metabolites ADC at long td (from 86 ms to 1011 ms) in a large voxel enclosing an equal proportion of white and grey matter. We showed that metabolites apparently diffuse freely along the axis of dendrites, axons and astrocytic processes. To assess potential differences between these two tissue types, here we measured for the first time in the Human brain the td-dependency of metabolites trace/3 ADC at 7 teslas using a localized diffusion-weighted STEAM sequence, in parietal and occipital voxels respectively containing mainly white and grey matter. We show that, in both tissues and over the observed timescale (td varying from 92 to 712 ms) metabolite ADC reaches a non-zero plateau, suggesting that metabolites are not confined inside subcellular regions such as cell bodies, or inside subcellular compartments such as organelles, but are rather free to diffuse in the whole fiber-like structure of neurons and astrocytes. Beyond the fundamental insights into intracellular compartmentation of metabolites, this work also provides a new framework for interpreting results of neuroimaging techniques based on molecular diffusion, such as diffusion-weighted magnetic resonance spectroscopy and imaging. PMID:25520054

Programming chemistry in DNA-addressable bioreactors

PubMed Central

Fellermann, Harold; Cardelli, Luca

2014-01-01

We present a formal calculus, termed the chemtainer calculus, able to capture the complexity of compartmentalized reaction systems such as populations of possibly nested vesicular compartments. Compartments contain molecular cargo as well as surface markers in the form of DNA single strands. These markers serve as compartment addresses and allow for their targeted transport and fusion, thereby enabling reactions of previously separated chemicals. The overall system organization allows for the set-up of programmable chemistry in microfluidic or other automated environments. We introduce a simple sequential programming language whose instructions are motivated by state-of-the-art microfluidic technology. Our approach integrates electronic control, chemical computing and material production in a unified formal framework that is able to mimic the integrated computational and constructive capabilities of the subcellular matrix. We provide a non-deterministic semantics of our programming language that enables us to analytically derive the computational and constructive power of our machinery. This semantics is used to derive the sets of all constructable chemicals and supermolecular structures that emerge from different underlying instruction sets. Because our proofs are constructive, they can be used to automatically infer control programs for the construction of target structures from a limited set of resource molecules. Finally, we present an example of our framework from the area of oligosaccharide synthesis. PMID:25121647

Metabolic flux analysis of heterotrophic growth in Chlamydomonas reinhardtii.

PubMed

Boyle, Nanette R; Sengupta, Neelanjan; Morgan, John A

2017-01-01

Despite the wealth of knowledge available for C. reinhardtii, the central metabolic fluxes of growth on acetate have not yet been determined. In this study, 13C-metabolic flux analysis (13C-MFA) was used to determine and quantify the metabolic pathways of primary metabolism in C. reinhardtii cells grown under heterotrophic conditions with acetate as the sole carbon source. Isotopic labeling patterns of compartment specific biomass derived metabolites were used to calculate the fluxes. It was found that acetate is ligated with coenzyme A in the three subcellular compartments (cytosol, mitochondria and plastid) included in the model. Two citrate synthases were found to potentially be involved in acetyl-coA metabolism; one localized in the mitochondria and the other acting outside the mitochondria. Labeling patterns demonstrate that Acetyl-coA synthesized in the plastid is directly incorporated in synthesis of fatty acids. Despite having a complete TCA cycle in the mitochondria, it was also found that a majority of the malate flux is shuttled to the cytosol and plastid where it is converted to oxaloacetate providing reducing equivalents to these compartments. When compared to predictions by flux balance analysis, fluxes measured with 13C-MFA were found to be suboptimal with respect to biomass yield; C. reinhardtii sacrifices biomass yield to produce ATP and reducing equivalents.

Capillary electrophoretic analysis reveals subcellular binding between individual mitochondria and cytoskeleton

PubMed Central

Kostal, Vratislav; Arriaga, Edgar A.

2011-01-01

Interactions between the cytoskeleton and mitochondria are essential for normal cellular function. An assessment of such interactions is commonly based on bulk analysis of mitochondrial and cytoskeletal markers present in a given sample, which assumes complete binding between these two organelle types. Such measurements are biased because they rarely account for non-bound ‘free’ subcellular species. Here we report on the use of capillary electrophoresis with dual laser induced fluorescence detection (CE-LIF) to identify, classify, count and quantify properties of individual binding events of mitochondria and cytoskeleton. Mitochondria were fluorescently labeled with DsRed2 while F-actin, a major cytoskeletal component, was fluorescently labeled with Alexa488-phalloidin. In a typical subcellular fraction of L6 myoblasts, 79% of mitochondrial events did not have detectable levels of F-actin, while the rest had on average ~2 zeptomole F-actin, which theoretically represents a ~ 2.5-μm long network of actin filaments per event. Trypsin treatment of L6 subcellular fractions prior to analysis decreased the fraction of mitochondrial events with detectable levels of F-actin, which is expected from digestion of cytoskeletal proteins on the surface of mitochondria. The electrophoretic mobility distributions of the individual events were also used to further distinguish between cytoskeleton-bound from cytoskeleton-free mitochondrial events. The CE-LIF approach described here could be further developed to explore cytoskeleton interactions with other subcellular structures, the effects of cytoskeleton destabilizing drugs, and the progression of viral infections. PMID:21309532

Cadmium biodynamics in the oligochaete Lumbriculus variegatus and its implications for trophic transfer

USGS Publications Warehouse

Xie, Lingtian; Lambert, D.; Martin, C.; Cain, D.J.; Luoma, S.N.; Buchwalter, D.

2008-01-01

It has become increasingly apparent that diet can be a major source of trace metal bioaccumulation in aquatic organisms. In this study, we examined cadmium uptake, efflux, and subcellular compartmentalization dynamics in the freshwater oligochaete Lumbriculus variegatus. L. variegatus is an important component of freshwater food webs in Europe and North America and is potentially useful as a standard food source for laboratory-based trophic transfer studies. Cadmium accumulation and depuration were each followed for 10 days. Rate constants of uptake (ku) and efflux (ke) were estimated and subcellular Cd compartmentalization was followed over the course of uptake and efflux. The partitioning of Cd into operationally-defined subcellular compartments was relatively consistent throughout the 20-day experiment, with the majority of Cd accumulating in the cytosol. No major changes in Cd compartmentalization were observed over uptake or depuration, but there appeared to be some exchange between heat-stable and heat-labile cytosolic protein fractions. Cadmium accumulation from solution was strongly affected by ambient calcium concentrations, suggesting competition between Cd and Ca for uptake sites. Finally, we demonstrate the ability to manipulate the whole body calcium content of L. variegatus as a potential tool for examining calcium influences on dietary Cd dynamics. The potential for this species to be an important conduit of Cd to higher trophic levels is discussed, along with its potential as a standardized food source in metal trophic transfer studies. ?? 2007 Elsevier B.V. All rights reserved.

mPLR-Loc: an adaptive decision multi-label classifier based on penalized logistic regression for protein subcellular localization prediction.

PubMed

Wan, Shibiao; Mak, Man-Wai; Kung, Sun-Yuan

2015-03-15

Proteins located in appropriate cellular compartments are of paramount importance to exert their biological functions. Prediction of protein subcellular localization by computational methods is required in the post-genomic era. Recent studies have been focusing on predicting not only single-location proteins but also multi-location proteins. However, most of the existing predictors are far from effective for tackling the challenges of multi-label proteins. This article proposes an efficient multi-label predictor, namely mPLR-Loc, based on penalized logistic regression and adaptive decisions for predicting both single- and multi-location proteins. Specifically, for each query protein, mPLR-Loc exploits the information from the Gene Ontology (GO) database by using its accession number (AC) or the ACs of its homologs obtained via BLAST. The frequencies of GO occurrences are used to construct feature vectors, which are then classified by an adaptive decision-based multi-label penalized logistic regression classifier. Experimental results based on two recent stringent benchmark datasets (virus and plant) show that mPLR-Loc remarkably outperforms existing state-of-the-art multi-label predictors. In addition to being able to rapidly and accurately predict subcellular localization of single- and multi-label proteins, mPLR-Loc can also provide probabilistic confidence scores for the prediction decisions. For readers' convenience, the mPLR-Loc server is available online (http://bioinfo.eie.polyu.edu.hk/mPLRLocServer). Copyright © 2014 Elsevier Inc. All rights reserved.

Formin' actin in the nucleus.

PubMed

Baarlink, Christian; Grosse, Robert

2014-01-01

Many if not most proteins can, under certain conditions, change cellular compartments, such as, for example, shuttling from the cytoplasm to the nucleus. Thus, many proteins may exert functions in various and very different subcellular locations, depending on the signaling context. A large amount of actin regulatory proteins has been detected in the mammalian cell nucleus, although their potential roles are much debated and are just beginning to emerge. Recently, members of the formin family of actin nucleators were also reported to dynamically localize to the nuclear environment. Here we discuss our findings that specific diaphanous-related formins can promote nuclear actin assembly in a signal-dependent manner.

Investigating the Relationship Between Soil Water Mobility and Stable Isotope Composition with Implications for the Ecohydrologic Separation Hypothesis

NASA Astrophysics Data System (ADS)

Shuler, J.; McNamara, J. P.; Benner, S. G.; Kohn, M. J.; Evans, S.

2017-12-01

The ecohydrologic separation (ES) hypothesis states that streams and plants return different soil water compartments to the atmosphere and that these compartments bear distinct isotopic compositions that can be used to infer soil water mobility. Recent studies have found isotopic evidence for ES in a variety of ecosystems, though interpretations of these data vary. ES investigations frequently suffer from low sampling frequencies as well as incomplete or missing soil moisture and matric potential data to support assumptions of soil water mobility. We sampled bulk soil water every 2-3 weeks in the upper 1 m of a hillslope profile from May 2016 to July 2017 in a semi-arid watershed outside Boise, ID. Twig samples of three plant species were also collected concurrently. Plant and soil water samples extracted via cryogenic vacuum distillation were analyzed for δ2H and δ18O composition. Soil moisture and soil matric potential sensors were installed at five and four depths in the profile, respectively. Shallow bulk soil water was progressively enriched in both isotopes over the growing season and plotted along a soil evaporation line in a plot of δ2H versus δ18O. Plant water during the growing season plotted below both the Local Meteoric Water Line and soil evaporation line. Plant water isotopic composition could not be traced to any source sampled in this study. Additionally, soil moisture and matric potential data revealed that soils were well-drained and that mobile soil water was unavailable throughout most of the growing season at the depths sampled. Soil water isotopic composition alone failed to predict mobility as observed in soil moisture and matric potential data. These results underscore the need for standard hydrologic definitions for the mobile and immobile compartments of soil water in future studies of the ES hypothesis and ecohydrologic processes in general.

Subcellular Localization of Arabidopsis 3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase1

PubMed Central

Leivar, Pablo; González, Víctor M.; Castel, Susanna; Trelease, Richard N.; López-Iglesias, Carmen; Arró, Montserrat; Boronat, Albert; Campos, Narciso; Ferrer, Albert; Fernàndez-Busquets, Xavier

2005-01-01

Plants produce diverse isoprenoids, which are synthesized in plastids, mitochondria, endoplasmic reticulum (ER), and the nonorganellar cytoplasm. 3-Hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR) catalyzes the synthesis of mevalonate, a rate-limiting step in the cytoplasmic pathway. Several branches of the pathway lead to the synthesis of structurally and functionally varied, yet essential, isoprenoids. Several HMGR isoforms have been identified in all plants examined. Studies based on gene expression and on fractionation of enzyme activity suggested that subcellular compartmentalization of HMGR is an important intracellular channeling mechanism for the production of the specific classes of isoprenoids. Plant HMGR has been shown previously to insert in vitro into the membrane of microsomal vesicles, but the final in vivo subcellular localization(s) remains controversial. To address the latter in Arabidopsis (Arabidopsis thaliana) cells, we conducted a multipronged microscopy and cell fractionation approach that included imaging of chimeric HMGR green fluorescent protein localizations in transiently transformed cell leaves, immunofluorescence confocal microscopy in wild-type and stably transformed seedlings, immunogold electron microscopy examinations of endogenous HMGR in seedling cotyledons, and sucrose density gradient analyses of HMGR-containing organelles. Taken together, the results reveal that endogenous Arabidopsis HMGR is localized at steady state within ER as expected, but surprisingly also predominantly within spherical, vesicular structures that range from 0.2- to 0.6-μm diameter, located in the cytoplasm and within the central vacuole in differentiated cotyledon cells. The N-terminal region, including the transmembrane domain of HMGR, was found to be necessary and sufficient for directing HMGR to ER and the spherical structures. It is believed, although not directly demonstrated, that these vesicle-like structures are derived from segments of HMGR-ER. Nevertheless, they represent a previously undescribed subcellular compartment likely capable of synthesizing mevalonate, which provides new evidence for multiorganelle compartmentalization of the isoprenoid biosynthetic pathways in plants. PMID:15618432

Distinct subcellular patterns of neprilysin protein and activity in the brains of Alzheimer’s disease patients, transgenic mice and cultured human neuronal cells

PubMed Central

Zhou, Li; Wei, Chunsheng; Huang, Wei; Bennett, David A; Dickson, Dennis W; Wang, Rui; Wang, Dengshun

2013-01-01

We investigated the subcellular distribution of NEP protein and activity in brains of human individuals with no cognitive impairment (NCI), mild cognitive impairment (MCI) and AD dementia, as well as double transgenic mice and human neuronal cell line treated with Aβ and 4-hydroxy-2-nonenal (HNE). Total cortical neuronal-related NEP was significantly increased in MCI compared to NCI brains. NeuN was decreased in both MCI and AD, consistent with neuronal loss occurring in MCI and AD. Negative relationship between NEP protein and NeuN in MCI brains, and positive correlation between NEP and pan-cadherin in NCI and MCI brains, suggesting the increased NEP expression in NCI and MCI might be due to membrane associated NEP in non-neuronal cells. In subcellular extracts, NEP protein decreased in cytoplasmic fractions in MCI and AD, but increased in membrane fractions, with a significant increase in the membrane/cytoplasmic ratio of NEP protein in AD brains. By contrast, NEP activity was decreased in AD. Similar results were observed in AD-mimic transgenic mice. Studies of SH-SY5Y neuroblastoma showed an up-regulation of NEP protein in the cytoplasmic compartment induced by HNE and Aβ; however, NEP activity decreased in cytoplasmic fractions. Activity of NEP in membrane fractions increased at 48 hours and then significantly decreased after treatment with HNE and Aβ. The cytoplasmic/membrane ratio of NEP protein increased at 24 hours and then decreased in both HNE and Aβ treated cells. Both HNE and Aβ up-regulate NEP expression, but NEP enzyme activity did not show the same increase, possibly indicating immature cytoplasmic NEP is less active than membrane associated NEP. These observations indicate that modulation of NEP protein levels and its subcellular location influence the net proteolytic activity and this complex association might participate in deficiency of Aβ degradation that is associated with amyloid deposition in AD. PMID:24093058

Automated processing of label-free Raman microscope images of macrophage cells with standardized regression for high-throughput analysis.

PubMed

Milewski, Robert J; Kumagai, Yutaro; Fujita, Katsumasa; Standley, Daron M; Smith, Nicholas I

2010-11-19

Macrophages represent the front lines of our immune system; they recognize and engulf pathogens or foreign particles thus initiating the immune response. Imaging macrophages presents unique challenges, as most optical techniques require labeling or staining of the cellular compartments in order to resolve organelles, and such stains or labels have the potential to perturb the cell, particularly in cases where incomplete information exists regarding the precise cellular reaction under observation. Label-free imaging techniques such as Raman microscopy are thus valuable tools for studying the transformations that occur in immune cells upon activation, both on the molecular and organelle levels. Due to extremely low signal levels, however, Raman microscopy requires sophisticated image processing techniques for noise reduction and signal extraction. To date, efficient, automated algorithms for resolving sub-cellular features in noisy, multi-dimensional image sets have not been explored extensively. We show that hybrid z-score normalization and standard regression (Z-LSR) can highlight the spectral differences within the cell and provide image contrast dependent on spectral content. In contrast to typical Raman imaging processing methods using multivariate analysis, such as single value decomposition (SVD), our implementation of the Z-LSR method can operate nearly in real-time. In spite of its computational simplicity, Z-LSR can automatically remove background and bias in the signal, improve the resolution of spatially distributed spectral differences and enable sub-cellular features to be resolved in Raman microscopy images of mouse macrophage cells. Significantly, the Z-LSR processed images automatically exhibited subcellular architectures whereas SVD, in general, requires human assistance in selecting the components of interest. The computational efficiency of Z-LSR enables automated resolution of sub-cellular features in large Raman microscopy data sets without compromise in image quality or information loss in associated spectra. These results motivate further use of label free microscopy techniques in real-time imaging of live immune cells.

Scanning ion conductance microscopy: a convergent high-resolution technology for multi-parametric analysis of living cardiovascular cells

PubMed Central

Miragoli, Michele; Moshkov, Alexey; Novak, Pavel; Shevchuk, Andrew; Nikolaev, Viacheslav O.; El-Hamamsy, Ismail; Potter, Claire M. F.; Wright, Peter; Kadir, S.H. Sheikh Abdul; Lyon, Alexander R.; Mitchell, Jane A.; Chester, Adrian H.; Klenerman, David; Lab, Max J.; Korchev, Yuri E.; Harding, Sian E.; Gorelik, Julia

2011-01-01

Cardiovascular diseases are complex pathologies that include alterations of various cell functions at the levels of intact tissue, single cells and subcellular signalling compartments. Conventional techniques to study these processes are extremely divergent and rely on a combination of individual methods, which usually provide spatially and temporally limited information on single parameters of interest. This review describes scanning ion conductance microscopy (SICM) as a novel versatile technique capable of simultaneously reporting various structural and functional parameters at nanometre resolution in living cardiovascular cells at the level of the whole tissue, single cells and at the subcellular level, to investigate the mechanisms of cardiovascular disease. SICM is a multimodal imaging technology that allows concurrent and dynamic analysis of membrane morphology and various functional parameters (cell volume, membrane potentials, cellular contraction, single ion-channel currents and some parameters of intracellular signalling) in intact living cardiovascular cells and tissues with nanometre resolution at different levels of organization (tissue, cellular and subcellular levels). Using this technique, we showed that at the tissue level, cell orientation in the inner and outer aortic arch distinguishes atheroprone and atheroprotected regions. At the cellular level, heart failure leads to a pronounced loss of T-tubules in cardiac myocytes accompanied by a reduction in Z-groove ratio. We also demonstrated the capability of SICM to measure the entire cell volume as an index of cellular hypertrophy. This method can be further combined with fluorescence to simultaneously measure cardiomyocyte contraction and intracellular calcium transients or to map subcellular localization of membrane receptors coupled to cyclic adenosine monophosphate production. The SICM pipette can be used for patch-clamp recordings of membrane potential and single channel currents. In conclusion, SICM provides a highly informative multimodal imaging platform for functional analysis of the mechanisms of cardiovascular diseases, which should facilitate identification of novel therapeutic strategies. PMID:21325316

Programming chemistry in DNA-addressable bioreactors.

PubMed

Fellermann, Harold; Cardelli, Luca

2014-10-06

We present a formal calculus, termed the chemtainer calculus, able to capture the complexity of compartmentalized reaction systems such as populations of possibly nested vesicular compartments. Compartments contain molecular cargo as well as surface markers in the form of DNA single strands. These markers serve as compartment addresses and allow for their targeted transport and fusion, thereby enabling reactions of previously separated chemicals. The overall system organization allows for the set-up of programmable chemistry in microfluidic or other automated environments. We introduce a simple sequential programming language whose instructions are motivated by state-of-the-art microfluidic technology. Our approach integrates electronic control, chemical computing and material production in a unified formal framework that is able to mimic the integrated computational and constructive capabilities of the subcellular matrix. We provide a non-deterministic semantics of our programming language that enables us to analytically derive the computational and constructive power of our machinery. This semantics is used to derive the sets of all constructable chemicals and supermolecular structures that emerge from different underlying instruction sets. Because our proofs are constructive, they can be used to automatically infer control programs for the construction of target structures from a limited set of resource molecules. Finally, we present an example of our framework from the area of oligosaccharide synthesis. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Characterizing the Specificity and Co-operation of Aminopeptidases in the Cytosol and ER During MHC Class I antigen Presentation1

PubMed Central

Hearn, Arron; York, Ian A.; Bishop, Courtney; Rock, Kenneth L.

2010-01-01

Many MHC class I binding peptides are generated as N-extended precursors during protein degradation by the proteasome. These peptides can be subsequently trimmed by aminopeptidases in the cytosol and/or the ER to produce mature epitope. However, the contribution and specificity of each of these subcellular compartments in removing N-terminal amino acids for antigen presentation is not well defined. Here we investigate this issue for antigenic precursors that are expressed in the cytosol. By systematically varying the N-terminal flanking sequences of peptides we show that the amino acids upstream of an epitope precursor are a major determinant of the amount of antigen presentation. In many cases MHC class I binding peptides are produced through sequential trimming in both the cytosol and ER. Trimming of flanking residues in the cytosol contributes most to sequences that are poorly trimmed in the ER. Since N-terminal trimming has different specificity in the cytosol and ER, the cleavage of peptides in both of these compartments serves to broaden the repertoire of sequences that are presented. PMID:20351195

The Histochemistry and Cell Biology omnium-gatherum: the year 2015 in review.

PubMed

Taatjes, Douglas J; Roth, Jürgen

2016-03-01

We provide here our annual review/synopsis of all of the articles published in Histochemistry and Cell Biology (HCB) for the preceding year. In 2015, HCB published 102 articles, representing a wide variety of topics and methodologies. For ease of access to these differing topics, we have created categories, as determined by the types of articles presented to provide a quick index representing the general areas covered. This year, these categories include: (1) advances in methodologies; (2) molecules in health and disease; (3) organelles, subcellular structures, and compartments; (4) the nucleus; (5) stem cells and tissue engineering; (6) cell cultures: properties and capabilities; (7) connective tissues and extracellular matrix; (8) developmental biology; (9) nervous system; (10) musculoskeletal system; (11) respiratory and cardiovascular system; (12) liver and gastrointestinal tract; and (13) male and female reproductive systems. Of note, the categories proceed from methods development, to molecules, intracellular compartments, stem cells and cell culture, extracellular matrix, developmental biology, and finishing with various organ systems, hopefully presenting a logical journey from methods to organismal molecules, cells, and whole tissue systems.

Isolation and characterization of a prokaryotic cell organelle from the anammox bacterium Kuenenia stuttgartiensis.

PubMed

Neumann, Sarah; Wessels, Hans J C T; Rijpstra, W Irene C; Sinninghe Damsté, Jaap S; Kartal, Boran; Jetten, Mike S M; van Niftrik, Laura

2014-11-01

Anaerobic ammonium oxidizing (anammox) bacteria oxidize ammonium with nitrite to nitrogen gas in the absence of oxygen. These microorganisms form a significant sink for fixed nitrogen in the oceans and the anammox process is applied as a cost-effective and environment-friendly nitrogen removal system from wastewater. Anammox bacteria have a compartmentalized cell plan that consists of three separate compartments. Here we report the fractionation of the anammox bacterium Kuenenia stuttgartiensis in order to isolate and analyze the innermost cell compartment called the anammoxosome. The subcellular fractions were microscopically characterized and all membranes in the anammox cell were shown to contain ladderane lipids which are unique for anammox bacteria. Proteome analyses and activity assays with the isolated anammoxosomes showed that these organelles harbor the energy metabolism in anammox cells. Together the experimental data provide the first thorough characterization of a respiratory cell organelle from a bacterium and demonstrate the essential role of the anammoxosome in the production of a major portion of the nitrogen gas in our atmosphere. © 2014 John Wiley & Sons Ltd.

Immunomagnetic isolation of pathogen-containing phagosomes and apoptotic blebs from primary phagocytes.

PubMed

Steinhäuser, Christine; Dallenga, Tobias; Tchikov, Vladimir; Schaible, Ulrich E; Schütze, Stefan; Reiling, Norbert

2014-04-02

Macrophages and polymorphonuclear neutrophils are professional phagocytes essential in the initial host response against intracellular pathogens such as Mycobacterium tuberculosis. Phagocytosis is the first step in phagocyte-pathogen interaction, where the pathogen is engulfed into a membrane-enclosed compartment termed a phagosome. Subsequent effector functions of phagocytes result in killing and degradation of the pathogen by promoting phagosome maturation, and, terminally, phago-lysosome fusion. Intracellular pathogenic microbes use various strategies to avoid detection and elimination by phagocytes, including induction of apoptosis to escape host cells, thereby generating apoptotic blebs as shuttles to other cells for pathogens and antigens thereof. Hence, phagosomes represent compartments where host and pathogen become quite intimate, and apoptotic blebs are carrier bags of the pathogen's legacy. In order to investigate the molecular mechanisms underlying these interactions, both phagosomes and apoptotic blebs are required as purified subcellular fractions for subsequent analysis of their biochemical properties. Here, we describe a lipid-based procedure to magnetically label surfaces of either pathogenic mycobacteria or apoptotic blebs for purification by a strong magnetic field in a novel free-flow system. Copyright © 2014 John Wiley & Sons, Inc.

Two-photon excited autofluorescence imaging of freshly isolated frog retinas.

PubMed

Lu, Rong-Wen; Li, Yi-Chao; Ye, Tong; Strang, Christianne; Keyser, Kent; Curcio, Christine A; Yao, Xin-Cheng

2011-06-01

The purpose of this study was to investigate cellular sources of autofluorescence signals in freshly isolated frog (Rana pipiens) retinas. Equipped with an ultrafast laser, a laser scanning two-photon excitation fluorescence microscope was employed for sub-cellular resolution examination of both sliced and flat-mounted retinas. Two-photon imaging of retinal slices revealed autofluorescence signals over multiple functional layers, including the photoreceptor layer (PRL), outer nuclear layer (ONL), outer plexiform layer (OPL), inner nuclear layer (INL), inner plexiform layer (IPL), and ganglion cell layer (GCL). Using flat-mounted retinas, depth-resolved imaging of individual retinal layers further confirmed multiple sources of autofluorescence signals. Cellular structures were clearly observed at the PRL, ONL, INL, and GCL. At the PRL, the autofluorescence was dominantly recorded from the intracellular compartment of the photoreceptors; while mixed intracellular and extracellular autofluorescence signals were observed at the ONL, INL, and GCL. High resolution autofluorescence imaging clearly revealed mosaic organization of rod and cone photoreceptors; and sub-cellular bright autofluorescence spots, which might relate to connecting cilium, was observed in the cone photoreceptors only. Moreover, single-cone and double-cone outer segments could be directly differentiated.

Cadmium ecophysiology in seven stonefly (Plecoptera) species: Delineating sources and estimating susceptibility

USGS Publications Warehouse

Martin, C.A.; Luoma, S.N.; Cain, D.J.; Buchwalter, D.B.

2007-01-01

A major challenge in ecotoxicology lies in generating data under experimental conditions that are relevant to understanding contaminant effects in nature. Biodynamic modeling combines species-specific physiological traits to make predictions of metal bioaccumulation that fare well when tested in the field. We generated biodynamic models for seven predatory stonefly (Plecoptera) species representing the families Perlidae (5) and Perlodidae (2). Each taxon was exposed to cadmium independently via diet and via solution. Species varied approximately 2.6 fold in predicted steady-state cadmium concentrations. Diet was the predominant source of accumulated cadmium in five of the seven species and averaged 53.2 ?? 9.6% and 90.2 ?? 3.7% of net Cd accumulation in perlids and perlodids, respectively. Differences in Cd bioaccumulation between the two families were largely driven by differences in dissolved accumulation rates, which were considerably slower in perlodids than in perlids. We further examined the subcellular compartmentalization of Cd accumulated from independent aqueous and dietary exposures. Predicted steady-state concentrations were modified to only consider Cd accumulated in metal-sensitive subcellular compartments. These values ranged 5.3 fold. We discuss this variability within a phylogenetic context and its implications for bioassessment. ?? 2007 American Chemical Society.

Intermediate filament proteins of digestive organs: physiology and pathophysiology.

PubMed

Omary, M Bishr

2017-06-01

Intermediate filament proteins (IFs), such as cytoplasmic keratins in epithelial cells and vimentin in mesenchymal cells and the nuclear lamins, make up one of the three major cytoskeletal protein families. Whether in digestive organs or other tissues, IFs share several unique features including stress-inducible overexpression, abundance, cell-selective and differentiation state expression, and association with >80 human diseases when mutated. Whereas most IF mutations cause disease, mutations in simple epithelial keratins 8, 18, or 19 or in lamin A/C predispose to liver disease with or without other tissue manifestations. Keratins serve major functions including protection from apoptosis, providing cellular and subcellular mechanical integrity, protein targeting to subcellular compartments, and scaffolding and regulation of cell-signaling processes. Keratins are essential for Mallory-Denk body aggregate formation that occurs in association with several liver diseases, whereas an alternate type of keratin and lamin aggregation occurs upon liver involvement in porphyria. IF-associated diseases have no known directed therapy, but high-throughput drug screening to identify potential therapies is an appealing ongoing approach. Despite the extensive current knowledge base, much remains to be discovered regarding IF physiology and pathophysiology in digestive and nondigestive organs. Copyright © 2017 the American Physiological Society.

Characterization and subcellular compartmentation of recombinant 4-hydroxyphenylpyruvate dioxygenase from Arabidopsis in transgenic tobacco.

PubMed

Garcia, I; Rodgers, M; Pepin, R; Hsieh, T F; Matringe, M

1999-04-01

4-Hydroxyphenylpyruvate dioxygenase (4HPPD) catalyzes the formation of homogentisate (2,5-dihydroxyphenylacetate) from p-hydroxyphenylpyruvate and molecular oxygen. In plants this enzyme activity is involved in two distinct metabolic processes, the biosynthesis of prenylquinones and the catabolism of tyrosine. We report here the molecular and biochemical characterization of an Arabidopsis 4HPPD and the compartmentation of the recombinant protein in chlorophyllous tissues. We isolated a 1508-bp cDNA with one large open reading frame of 1338 bp. Southern analysis strongly suggested that this Arabidopsis 4HPPD is encoded by a single-copy gene. We investigated the biochemical characteristics of this 4HPPD by overproducing the recombinant protein in Escherichia coli JM105. The subcellular localization of the recombinant 4HPPD in chlorophyllous tissues was examined by overexpressing its complete coding sequence in transgenic tobacco (Nicotiana tabacum), using Agrobacterium tumefaciens transformation. We performed western analyses for the immunodetection of protein extracts from purified chloroplasts and total leaf extracts and for the immunocytochemistry on tissue sections. These analyses clearly revealed that 4HPPD was confined to the cytosol compartment, not targeted to the chloroplast. Western analyses confirmed the presence of a cytosolic form of 4HPPD in cultured green Arabidopsis cells.

Functional analysis of the Arabidopsis PHT4 family of intracellular phosphate transporters.

PubMed

Guo, B; Jin, Y; Wussler, C; Blancaflor, E B; Motes, C M; Versaw, W K

2008-01-01

The transport of phosphate (Pi) between subcellular compartments is central to metabolic regulation. Although some of the transporters involved in controlling the intracellular distribution of Pi have been identified in plants, others are predicted from genetic, biochemical and bioinformatics studies. Heterologous expression in yeast, and gene expression and localization in plants were used to characterize all six members of an Arabidopsis thaliana membrane transporter family designated here as PHT4. PHT4 proteins share similarity with SLC17/type I Pi transporters, a diverse group of animal proteins involved in the transport of Pi, organic anions and chloride. All of the PHT4 proteins mediate Pi transport in yeast with high specificity. Bioinformatic analysis and localization of PHT4-GFP fusion proteins indicate that five of the proteins are targeted to the plastid envelope, and the sixth resides in the Golgi apparatus. PHT4 genes are expressed in both roots and leaves, although two of the genes are expressed predominantly in leaves and one mostly in roots. These expression patterns, together with Pi transport activities and subcellular locations, suggest roles for PHT4 proteins in the transport of Pi between the cytosol and chloroplasts, heterotrophic plastids and the Golgi apparatus.

Arginine Decarboxylase Is Localized in Chloroplasts.

PubMed Central

Borrell, A.; Culianez-Macia, F. A.; Altabella, T.; Besford, R. T.; Flores, D.; Tiburcio, A. F.

1995-01-01

Plants, unlike animals, can use either ornithine decarboxylase or arginine decarboxylase (ADC) to produce the polyamine precursor putrescine. Lack of knowledge of the exact cellular and subcellular location of these enzymes has been one of the main obstacles to our understanding of the biological role of polyamines in plants. We have generated polyclonal antibodies to oat (Avena sativa L.) ADC to study the spatial distribution and subcellular localization of ADC protein in different oat tissues. By immunoblotting and immunocytochemistry, we show that ADC is organ specific. By cell fractionation and immunoblotting, we show that ADC is localized in chloroplasts associated with the thylakoid membrane. The results also show that increased levels of ADC protein are correlated with high levels of ADC activity and putrescine in osmotically stressed oat leaves. A model of compartmentalization for the arginine pathway and putrescine biosynthesis in active photosynthetic tissues has been proposed. In the context of endosymbiote-driven metabolic evolution in plants, the location of ADC in the chloroplast compartment may have major evolutionary significance, since it explains (a) why plants can use two alternative pathways for putrescine biosynthesis and (b) why animals do not possess ADC. PMID:12228631

Redox sensing: Orthogonal control in cell cycle and apoptosis signaling

PubMed Central

Jones, Dean P.

2010-01-01

Living systems have three major types of cell signaling systems that are dependent upon high-energy chemicals, redox environment and transmembranal ion gating mechanisms. Development of integrated systems biology descriptions of cell signaling require conceptual models incorporating all three. Recent advances in redox biology show that thiol/disulfide redox systems are regulated under dynamic, non-equilibrium conditions, progressively oxidized with the life cycle of cells and distinct in terms of redox potentials among subcellular compartments. The present article uses these observations as a basis to distinguish “redox-sensing” mechanisms, which are more global biologic redox control mechanisms, from “redox signaling”, which involves conveyance of discrete activating or inactivating signals. Both redox sensing and redox signaling use sulfur switches, especially cysteine (Cys) residues in proteins which are sensitive to reversible oxidation, nitrosylation, glutathionylation, acylation, sulfhydration or metal binding. Unlike specific signaling mechanisms, the redox-sensing mechanisms provide means to globally affect the rates and activities of the high-energy, ion gating and redox-signaling systems by controlling sensitivity, distribution, macromolecular interactions and mobility of signaling proteins. Effects mediated through Cys residues not directly involved in signaling means redox-sensing control can be orthogonal to the signaling mechanisms. This provides a capability to integrate signals according to cell cycle and physiologic state without fundamentally altering the signaling mechanisms. Recent findings that thiol/disulfide pools in humans are oxidized with age, environmental exposures and disease risk suggest that redox-sensing thiols could provide a central mechanistic link in disease development and progression. PMID:20964735

Overlapping expression patterns and functions of three paralogous P5B ATPases in Caenorhabditis elegans.

PubMed

Zielich, Jeffrey; Tzima, Elena; Schröder, Eva Ayla; Jemel, Faten; Conradt, Barbara; Lambie, Eric J

2018-01-01

P5B ATPases are present in the genomes of diverse unicellular and multicellular eukaryotes, indicating that they have an ancient origin, and that they are important for cellular fitness. Inactivation of ATP13A2, one of the four human P5B ATPases, leads to early-onset Parkinson's disease (Kufor-Rakeb Syndrome). The presence of an invariant PPALP motif within the putative substrate interaction pocket of transmembrane segment M4 suggests that all P5B ATPases might have similar transport specificity; however, the identity of the transport substrate(s) remains unknown. Nematodes of the genus Caenorhabditis possess three paralogous P5B ATPase genes, catp-5, catp-6 and catp-7, which probably originated from a single ancestral gene around the time of origin of the Caenorhabditid clade. By using CRISPR/Cas9, we have systematically investigated the expression patterns, subcellular localization and biological functions of each of the P5B ATPases of C. elegans. We find that each gene has a unique expression pattern, and that some tissues express more than one P5B. In some tissues where their expression patterns overlap, different P5Bs are targeted to different subcellular compartments (e.g., early endosomes vs. plasma membrane), whereas in other tissues they localize to the same compartment (plasma membrane). We observed lysosomal co-localization between CATP-6::GFP and LMP-1::RFP in transgenic animals; however, this was an artifact of the tagged LMP-1 protein, since anti-LMP-1 antibody staining of native protein revealed that LMP-1 and CATP-6::GFP occupy different compartments. The nematode P5Bs are at least partially redundant, since we observed synthetic sterility in catp-5(0); catp-6(0) and catp-6(0) catp-7(0) double mutants. The double mutants exhibit defects in distal tip cell migration that resemble those of ina-1 (alpha integrin ortholog) and vab-3 (Pax6 ortholog) mutants, suggesting that the nematode P5Bs are required for ina-1and/or vab-3 function. This is potentially a conserved regulatory interaction, since mammalian ATP13A2, alpha integrin and Pax6 are all required for proper dopaminergic neuron function.

Overlapping expression patterns and functions of three paralogous P5B ATPases in Caenorhabditis elegans

PubMed Central

Zielich, Jeffrey; Tzima, Elena; Schröder, Eva Ayla; Jemel, Faten; Conradt, Barbara

2018-01-01

P5B ATPases are present in the genomes of diverse unicellular and multicellular eukaryotes, indicating that they have an ancient origin, and that they are important for cellular fitness. Inactivation of ATP13A2, one of the four human P5B ATPases, leads to early-onset Parkinson’s disease (Kufor-Rakeb Syndrome). The presence of an invariant PPALP motif within the putative substrate interaction pocket of transmembrane segment M4 suggests that all P5B ATPases might have similar transport specificity; however, the identity of the transport substrate(s) remains unknown. Nematodes of the genus Caenorhabditis possess three paralogous P5B ATPase genes, catp-5, catp-6 and catp-7, which probably originated from a single ancestral gene around the time of origin of the Caenorhabditid clade. By using CRISPR/Cas9, we have systematically investigated the expression patterns, subcellular localization and biological functions of each of the P5B ATPases of C. elegans. We find that each gene has a unique expression pattern, and that some tissues express more than one P5B. In some tissues where their expression patterns overlap, different P5Bs are targeted to different subcellular compartments (e.g., early endosomes vs. plasma membrane), whereas in other tissues they localize to the same compartment (plasma membrane). We observed lysosomal co-localization between CATP-6::GFP and LMP-1::RFP in transgenic animals; however, this was an artifact of the tagged LMP-1 protein, since anti-LMP-1 antibody staining of native protein revealed that LMP-1 and CATP-6::GFP occupy different compartments. The nematode P5Bs are at least partially redundant, since we observed synthetic sterility in catp-5(0); catp-6(0) and catp-6(0) catp-7(0) double mutants. The double mutants exhibit defects in distal tip cell migration that resemble those of ina-1 (alpha integrin ortholog) and vab-3 (Pax6 ortholog) mutants, suggesting that the nematode P5Bs are required for ina-1and/or vab-3 function. This is potentially a conserved regulatory interaction, since mammalian ATP13A2, alpha integrin and Pax6 are all required for proper dopaminergic neuron function. PMID:29547664

Human cell structure-driven model construction for predicting protein subcellular location from biological images.

PubMed

Shao, Wei; Liu, Mingxia; Zhang, Daoqiang

2016-01-01

The systematic study of subcellular location pattern is very important for fully characterizing the human proteome. Nowadays, with the great advances in automated microscopic imaging, accurate bioimage-based classification methods to predict protein subcellular locations are highly desired. All existing models were constructed on the independent parallel hypothesis, where the cellular component classes are positioned independently in a multi-class classification engine. The important structural information of cellular compartments is missed. To deal with this problem for developing more accurate models, we proposed a novel cell structure-driven classifier construction approach (SC-PSorter) by employing the prior biological structural information in the learning model. Specifically, the structural relationship among the cellular components is reflected by a new codeword matrix under the error correcting output coding framework. Then, we construct multiple SC-PSorter-based classifiers corresponding to the columns of the error correcting output coding codeword matrix using a multi-kernel support vector machine classification approach. Finally, we perform the classifier ensemble by combining those multiple SC-PSorter-based classifiers via majority voting. We evaluate our method on a collection of 1636 immunohistochemistry images from the Human Protein Atlas database. The experimental results show that our method achieves an overall accuracy of 89.0%, which is 6.4% higher than the state-of-the-art method. The dataset and code can be downloaded from https://github.com/shaoweinuaa/. dqzhang@nuaa.edu.cn Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Subcellular SIMS imaging of isotopically labeled amino acids in cryogenically prepared cells

NASA Astrophysics Data System (ADS)

Chandra, Subhash

2004-06-01

Ion microscopy is a potentially powerful technique for localization of isotopically labeled molecules. In this study, L-arginine and phenylalanine amino acids labeled with stable isotopes 13C and 15N were localized in cultured cells with the ion microscope at 500 nm spatial resolution. Cells were exposed to the labeled amino acids and cryogenically prepared. SIMS analyses were made in fractured freeze-dried cells. A dynamic distribution was observed from labeled arginine-treated LLC-PK 1 kidney cells at mass 28 ( 13C15N) in negative secondaries, revealing cell-to-cell heterogeneity and preferential accumulation of the amino acid (or its metabolite) in the nucleus and nucleolus of some cells. The smaller nucleolus inside the nucleus was clearly resolved in SIMS images and confirmed by correlative light microscopy. The distribution of labeled phenylalanine contrasted with arginine as it was rather homogeneously distributed in T98G human glioblastoma cells. Images of 39K, 23Na and 40Ca were also recorded to confirm the reliability of sample preparation and authenticity of the observed amino acid distributions. These observations indicate that SIMS techniques can provide a valuable technology for subcellular localization of nitrogen-containing molecules in proteomics since nitrogen does not have a radionuclide tracer isotope. Amino acids labeled with stable isotopes can be used as tracers for studying their transport and metabolism in distinct subcellular compartments with SIMS. Further studies of phenylalanine uptake in human glioblastoma cells may have special significance in boron neutron capture therapy (BNCT) as a boron analogue of phenylalanine, boronophenylalanine is a clinically approved compound for the treatment of brain tumors.

Subcellular colocalization of the cellular and scrapie prion proteins in caveolae-like membranous domains

PubMed Central

Vey, Martin; Pilkuhn, Susanne; Wille, Holger; Nixon, Randal; DeArmond, Stephen J.; Smart, Eric J.; Anderson, Richard G. W.; Taraboulos, Albert; Prusiner, Stanley B.

1996-01-01

Results of transgenetic studies argue that the scrapie isoform of the prion protein (PrPSc) interacts with the substrate cellular PrP (PrPC) during conversion into nascent PrPSc. While PrPSc appears to accumulate primarily in lysosomes, caveolae-like domains (CLDs) have been suggested to be the site where PrPC is converted into PrPSc. We report herein that CLDs isolated from scrapie-infected neuroblastoma (ScN2a) cells contain PrPC and PrPSc. After lysis of ScN2a cells in ice-cold Triton X-100, both PrP isoforms and an N-terminally truncated form of PrPC (PrPC-II) were found concentrated in detergent-insoluble complexes resembling CLDs that were isolated by flotation in sucrose gradients. Similar results were obtained when CLDs were purified from plasma membranes by sonication and gradient centrifugation; with this procedure no detergents are used, which minimizes artifacts that might arise from redistribution of proteins among subcellular fractions. The caveolar markers ganglioside GM1 and H-ras were found concentrated in the CLD fractions. When plasma membrane proteins were labeled with the impermeant reagent sulfo-N-hydroxysuccinimide-biotin, both PrPC and PrPSc were found biotinylated in CLD fractions. Similar results on the colocalization of PrPC and PrPSc were obtained when CLDs were isolated from Syrian hamster brains. Our findings demonstrate that both PrPC and PrPSc are present in CLDs and, thus, support the hypothesis that the PrPSc formation occurs within this subcellular compartment. PMID:8962161

Three-dimensional imaging of cholesterol and sphingolipids within a Madin-Darby canine kidney cell

DOE PAGES

Yeager, Ashley N.; Weber, Peter K.; Kraft, Mary L.

2016-01-08

Metabolic stable isotope incorporation and secondary ion mass spectrometry(SIMS) depth profiling performed on a Cameca NanoSIMS 50 were used to image the 18O-cholesterol and 15N-sphingolipid distributions within a portion of a Madin-Darby canine kidney (MDCK) cell. Three-dimensional representations of the component-specific isotope distributions show clearly defined regions of 18O-cholesterol and 15N-sphingolipid enrichment that seem to be separate subcellular compartments. Furthermore, the low levels of nitrogen-containing secondary ions detected at the 18O-enriched regions suggest that these 18O-cholesterol-rich structures may be lipiddroplets, which have a core consisting of cholesterol esters and triacylglycerides.

The emerging role of nuclear viral DNA sensors.

PubMed

Diner, Benjamin A; Lum, Krystal K; Cristea, Ileana M

2015-10-30

Detecting pathogenic DNA by intracellular receptors termed "sensors" is critical toward galvanizing host immune responses and eliminating microbial infections. Emerging evidence has challenged the dogma that sensing of viral DNA occurs exclusively in sub-cellular compartments normally devoid of cellular DNA. The interferon-inducible protein IFI16 was shown to bind nuclear viral DNA and initiate immune signaling, culminating in antiviral cytokine secretion. Here, we review the newly characterized nucleus-originating immune signaling pathways, their links to other crucial host defenses, and unique mechanisms by which viruses suppress their functions. We frame these findings in the context of human pathologies associated with nuclear replicating DNA viruses. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Three-dimensional imaging of cholesterol and sphingolipids within a Madin-Darby canine kidney cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeager, Ashley N.; Weber, Peter K.; Kraft, Mary L.

Metabolic stable isotope incorporation and secondary ion mass spectrometry(SIMS) depth profiling performed on a Cameca NanoSIMS 50 were used to image the 18O-cholesterol and 15N-sphingolipid distributions within a portion of a Madin-Darby canine kidney (MDCK) cell. Three-dimensional representations of the component-specific isotope distributions show clearly defined regions of 18O-cholesterol and 15N-sphingolipid enrichment that seem to be separate subcellular compartments. Furthermore, the low levels of nitrogen-containing secondary ions detected at the 18O-enriched regions suggest that these 18O-cholesterol-rich structures may be lipiddroplets, which have a core consisting of cholesterol esters and triacylglycerides.

Interferon-inducible effector mechanisms in cell-autonomous immunity

PubMed Central

MacMicking, John D.

2014-01-01

Interferons (IFNs) induce the expression of hundreds of genes as part of an elaborate antimicrobial programme designed to combat infection in all nucleated cells — a process termed cell-autonomous immunity. As described in this Review, recent genomic and subgenomic analyses have begun to assign functional properties to novel IFN-inducible effector proteins that restrict bacteria, protozoa and viruses in different subcellular compartments and at different stages of the pathogen life cycle. Several newly described host defence factors also participate in canonical oxidative and autophagic pathways by spatially coordinating their activities to enhance microbial killing. Together, these IFN-induced effector networks help to confer vertebrate host resistance to a vast and complex microbial world. PMID:22531325

[Ca2+]i Elevation and Oxidative Stress Induce KCNQ1 Protein Translocation from the Cytosol to the Cell Surface and Increase Slow Delayed Rectifier (IKs) in Cardiac Myocytes*

PubMed Central

Wang, Yuhong; Zankov, Dimitar P.; Jiang, Min; Zhang, Mei; Henderson, Scott C.; Tseng, Gea-Ny

2013-01-01

Our goals are to simultaneously determine the three-dimensional distribution patterns of KCNQ1 and KCNE1 in cardiac myocytes and to study the mechanism and functional implications for variations in KCNQ1/KCNE1 colocalization in myocytes. We monitored the distribution patterns of KCNQ1, KCNE1, and markers for subcellular compartments/organelles using immunofluorescence/confocal microscopy and confirmed the findings in ventricular myocytes by directly observing fluorescently tagged KCNQ1-GFP and KCNE1-dsRed expressed in these cells. We also monitored the effects of stress on KCNQ1-GFP and endoplasmic reticulum (ER) remodeling during live cell imaging. The data showed that 1) KCNE1 maintained a stable cell surface localization, whereas KCNQ1 exhibited variations in the cytosolic compartment (striations versus vesicles) and the degree of presence on the cell surface; 2) the degree of cell surface KCNQ1/KCNE1 colocalization was positively correlated with slow delayed rectifier (IKs) current density; 3) KCNQ1 and calnexin (an ER marker) shared a cytosolic compartment; and 4) in response to stress ([Ca2+]i elevation, oxidative overload, or AT1R stimulation), KCNQ1 exited the cytosolic compartment and trafficked to the cell periphery in vesicles. This was accompanied by partial ER fragmentation. We conclude that the cellular milieu regulates KCNQ1 distribution in cardiac myocytes and that stressful conditions can increase IKs by inducing KCNQ1 movement to the cell surface. This represents a hitherto unrecognized mechanism by which IKs fulfills its function as a repolarization reserve in ventricular myocytes. PMID:24142691

Spatial separation of the processing and MHC class I loading compartments for cross-presentation of the tumor-associated antigen HER2/neu by human dendritic cells

PubMed Central

Baleeiro, Renato B; Rietscher, René; Diedrich, Andrea; Czaplewska, Justyna A; Lehr, Claus-Michael; Scherließ, Regina; Hanefeld, Andrea; Gottschaldt, Michael; Walden, Peter

2015-01-01

Cross-presentation is the process by which professional antigen presenting cells (APCs) (B cells, dendritic cells (DCs) and macrophages) present endocytosed antigens (Ags) via MHC-I to CD8+ T cells. This process is crucial for induction of adaptive immune responses against tumors and infected cells. The pathways and cellular compartments involved in cross-presentation are unresolved and controversial. Among the cells with cross-presenting capacity, DCs are the most efficient, which was proposed to depend on prevention of endosomal acidification to block degradation of the epitopes. Contrary to this view, we show in this report that some cargoes induce strong endosomal acidification following uptake by human DCs, while others not. Moreover, processing of the tumor-associated antigen HER2/neu delivered in nanoparticles (NP) for cross-presentation of the epitope HER2/neu369–377 on HLA-A2 depended on endosomal acidification and cathepsin activity as well as proteasomes, and newly synthesized HLA class I. However, the HLA-A*0201/HER2/neu369–377 complexes were not found in the endoplasmic reticulum (ER) nor in endolysosomes but in hitherto not described vesicles. The data thus indicate spatial separation of antigen processing and loading of MHC-I for cross-presentation: antigen processing occurs in the uptake compartment and the cytosol whereas MHC-I loading with peptide takes place in a distinct subcellular compartment. The findings further elucidate the cellular pathways involved in the cross-presentation of a full-length, clinically relevant tumor-associated antigen by human DCs, and the impact of the vaccine formulation on antigen processing and CD8+ T cell induction. PMID:26985398

Kaposi's Sarcoma-Associated Herpesvirus mRNA Accumulation in Nuclear Foci Is Influenced by Viral DNA Replication and Viral Noncoding Polyadenylated Nuclear RNA.

PubMed

Vallery, Tenaya K; Withers, Johanna B; Andoh, Joana A; Steitz, Joan A

2018-07-01

Kaposi's sarcoma-associated herpesvirus (KSHV), like other herpesviruses, replicates within the nuclei of its human cell host and hijacks host machinery for expression of its genes. The activities that culminate in viral DNA synthesis and assembly of viral proteins into capsids physically concentrate in nuclear areas termed viral replication compartments. We sought to better understand the spatiotemporal regulation of viral RNAs during the KSHV lytic phase by examining and quantifying the subcellular localization of select viral transcripts. We found that viral mRNAs, as expected, localized to the cytoplasm throughout the lytic phase. However, dependent on active viral DNA replication, viral transcripts also accumulated in the nucleus, often in foci in and around replication compartments, independent of the host shutoff effect. Our data point to involvement of the viral long noncoding polyadenylated nuclear (PAN) RNA in the localization of an early, intronless viral mRNA encoding ORF59-58 to nuclear foci that are associated with replication compartments. IMPORTANCE Late in the lytic phase, mRNAs from Kaposi's sarcoma-associated herpesvirus accumulate in the host cell nucleus near viral replication compartments, centers of viral DNA synthesis and virion production. This work contributes spatiotemporal data on herpesviral mRNAs within the lytic host cell and suggests a mechanism for viral RNA accumulation. Our findings indicate that the mechanism is independent of the host shutoff effect and splicing but dependent on active viral DNA synthesis and in part on the viral noncoding RNA, PAN RNA. PAN RNA is essential for the viral life cycle, and its contribution to the nuclear accumulation of viral messages may facilitate propagation of the virus. Copyright © 2018 American Society for Microbiology.

Novel Reporter for Faithful Monitoring of ERK2 Dynamics in Living Cells and Model Organisms

PubMed Central

Sipieter, François; Cappe, Benjamin; Gonzalez Pisfil, Mariano; Spriet, Corentin; Bodart, Jean-François; Cailliau-Maggio, Katia; Vandenabeele, Peter; Héliot, Laurent; Riquet, Franck B.

2015-01-01

Uncoupling of ERK1/2 phosphorylation from subcellular localization is essential towards the understanding of molecular mechanisms that control ERK1/2-mediated cell-fate decision. ERK1/2 non-catalytic functions and discoveries of new specific anchors responsible of the subcellular compartmentalization of ERK1/2 signaling pathway have been proposed as regulation mechanisms for which dynamic monitoring of ERK1/2 localization is necessary. However, studying the spatiotemporal features of ERK2, for instance, in different cellular processes in living cells and tissues requires a tool that can faithfully report on its subcellular distribution. We developed a novel molecular tool, ERK2-LOC, based on the T2A-mediated coexpression of strictly equimolar levels of eGFP-ERK2 and MEK1, to faithfully visualize ERK2 localization patterns. MEK1 and eGFP-ERK2 were expressed reliably and functionally both in vitro and in single living cells. We then assessed the subcellular distribution and mobility of ERK2-LOC using fluorescence microscopy in non-stimulated conditions and after activation/inhibition of the MAPK/ERK1/2 signaling pathway. Finally, we used our coexpression system in Xenopus laevis embryos during the early stages of development. This is the first report on MEK1/ERK2 T2A-mediated coexpression in living embryos, and we show that there is a strong correlation between the spatiotemporal subcellular distribution of ERK2-LOC and the phosphorylation patterns of ERK1/2. Our approach can be used to study the spatiotemporal localization of ERK2 and its dynamics in a variety of processes in living cells and embryonic tissues. PMID:26517832

Studying Coxiella burnetii Type IV Substrates in the Yeast Saccharomyces cerevisiae: Focus on Subcellular Localization and Protein Aggregation.

PubMed

Rodríguez-Escudero, María; Cid, Víctor J; Molina, María; Schulze-Luehrmann, Jan; Lührmann, Anja; Rodríguez-Escudero, Isabel

2016-01-01

Coxiella burnetii is a Gram-negative obligate parasitic bacterium that causes the disease Q-fever in humans. To establish its intracellular niche, it utilizes the Icm/Dot type IVB secretion system (T4BSS) to inject protein effectors into the host cell cytoplasm. The host targets of most cognate and candidate T4BSS-translocated effectors remain obscure. We used the yeast Saccharomyces cerevisiae as a model to express and study six C. burnetii effectors, namely AnkA, AnkB, AnkF, CBU0077, CaeA and CaeB, in search for clues about their role in C. burnetii virulence. When ectopically expressed in HeLa cells, these effectors displayed distinct subcellular localizations. Accordingly, GFP fusions of these proteins produced in yeast also decorated distinct compartments, and most of them altered cell growth. CaeA was ubiquitinated both in yeast and mammalian cells and, in S. cerevisiae, accumulated at juxtanuclear quality-control compartments (JUNQs) and insoluble protein deposits (IPODs), characteristic of aggregative or misfolded proteins. AnkA, which was not ubiquitinated, accumulated exclusively at the IPOD. CaeA, but not AnkA or the other effectors, caused oxidative damage in yeast. We discuss that CaeA and AnkA behavior in yeast may rather reflect misfolding than recognition of conserved targets in the heterologous system. In contrast, CBU0077 accumulated at vacuolar membranes and abnormal ER extensions, suggesting that it interferes with vesicular traffic, whereas AnkB associated with the yeast nucleolus. Both effectors shared common localization features in HeLa and yeast cells. Our results support the idea that C. burnetii T4BSS effectors manipulate multiple host cell targets, which can be conserved in higher and lower eukaryotic cells. However, the behavior of CaeA and AnkA prompt us to conclude that heterologous protein aggregation and proteostatic stress can be a limitation to be considered when using the yeast model to assess the function of bacterial effectors.

Cellular internalization mechanism and intracellular trafficking of filamentous M13 phages displaying a cell-penetrating transbody and TAT peptide.

PubMed

Kim, Aeyung; Shin, Tae-Hwan; Shin, Seung-Min; Pham, Chuong D; Choi, Dong-Ki; Kwon, Myung-Hee; Kim, Yong-Sung

2012-01-01

Cellular internalization of bacteriophage by surface-displayed cell penetrating peptides has been reported, though the underlying mechanism remains elusive. Here we describe in detail the internalization mechanism and intracellular trafficking and stability of filamentous M13 phages, the cellular entry of which is mediated by surface-displayed cell-penetrating light chain variable domain 3D8 VL transbody (3D8 VL-M13) or TAT peptide (TAT-M13). Recombinant 3D8 VL-M13 and TAT-M13 phages were efficiently internalized into living mammalian cells via physiologically relevant, energy-dependent endocytosis and were recovered from the cells in their infective form with the yield of 3D8 VL-M13 being higher (0.005 ≈ 0.01%) than that of TAT-M13 (0.001 ≈ 0.005%). Biochemical and genetic studies revealed that 3D8 VL-M13 was internalized principally by caveolae-mediated endocytosis via interaction with heparan sulfate proteoglycans as cell surface receptors, whereas TAT-M13 was internalized by clathrin- and caveolae-mediated endocytosis utilizing chondroitin sulfate proteoglycans as cell surface receptors, suggesting that phage internalization occurs by physiological endocytotic mechanism through specific cell surface receptors rather than non-specific transcytotic pathways. Internalized 3D8 VL-M13 phages routed to the cytosol and remained stable for more than 18 h without further trafficking to other subcellular compartments, whereas TAT-M13 phages routed to several subcellular compartments before being degraded in lysosomes even after 2 h of internalization. Our results suggest that the internalizing mechanism and intracellular trafficking of filamentous M13 bacteriophages largely follow the attributes of the displayed cell-penetrating moiety. Efficient internalization and cytosolic localization of 3D8 VL transbody-displayed phages will provide a useful tool for intracellular delivery of polar macromolecules such as proteins, peptides, and siRNAs.

Cellular Internalization Mechanism and Intracellular Trafficking of Filamentous M13 Phages Displaying a Cell-Penetrating Transbody and TAT Peptide

PubMed Central

Shin, Seung-Min; Pham, Chuong D.; Choi, Dong-Ki; Kwon, Myung-Hee; Kim, Yong-Sung

2012-01-01

Cellular internalization of bacteriophage by surface-displayed cell penetrating peptides has been reported, though the underlying mechanism remains elusive. Here we describe in detail the internalization mechanism and intracellular trafficking and stability of filamentous M13 phages, the cellular entry of which is mediated by surface-displayed cell-penetrating light chain variable domain 3D8 VL transbody (3D8 VL-M13) or TAT peptide (TAT-M13). Recombinant 3D8 VL-M13 and TAT-M13 phages were efficiently internalized into living mammalian cells via physiologically relevant, energy-dependent endocytosis and were recovered from the cells in their infective form with the yield of 3D8 VL-M13 being higher (0.005∼0.01%) than that of TAT-M13 (0.001∼0.005%). Biochemical and genetic studies revealed that 3D8 VL-M13 was internalized principally by caveolae-mediated endocytosis via interaction with heparan sulfate proteoglycans as cell surface receptors, whereas TAT-M13 was internalized by clathrin- and caveolae-mediated endocytosis utilizing chondroitin sulfate proteoglycans as cell surface receptors, suggesting that phage internalization occurs by physiological endocytotic mechanism through specific cell surface receptors rather than non-specific transcytotic pathways. Internalized 3D8 VL-M13 phages routed to the cytosol and remained stable for more than 18 h without further trafficking to other subcellular compartments, whereas TAT-M13 phages routed to several subcellular compartments before being degraded in lysosomes even after 2 h of internalization. Our results suggest that the internalizing mechanism and intracellular trafficking of filamentous M13 bacteriophages largely follow the attributes of the displayed cell-penetrating moiety. Efficient internalization and cytosolic localization of 3D8 VL transbody-displayed phages will provide a useful tool for intracellular delivery of polar macromolecules such as proteins, peptides, and siRNAs. PMID:23251631

From the Cover: Vulnerability of C6 Astrocytoma Cells After Single-Compound and Joint Exposure to Type I and Type II Pyrethroid Insecticides.

PubMed

Romero, Delfina M; Berardino, Bruno G; Wolansky, Marcelo J; Kotler, Mónica L

2017-01-01

A primary mode-of-action of all pyrethroid insecticides (PYRs) is the disruption of the voltage-gated sodium channel electrophysiology in neurons of target pests and nontarget species. The neurological actions of PYRs on non-neuronal cells of the nervous system remain poorly investigated. In the present work, we used C6 astrocytoma cells to study PYR actions (0.1-50 μM) under the hypothesis that glial cells may be targeted by and vulnerable to PYRs. To this end, we characterized the effects of bifenthrin (BF), tefluthrin (TF), α-cypermethrin (α-CYP), and deltamethrin (DM) on the integrity of nuclear, mitochondrial, and lysosomal compartments. In general, 24- to 48-h exposures produced concentration-related impairment of cell viability. In single-compound, 24-h exposure experiments, effective concentration (EC) 15 s 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT assay) were computed as follows (in μM): BF, 16.1; TF, 37.3; α-CYP, 7.8; DM, 5.0. We found concentration-related damage in several C6-cell subcellular compartments (mitochondria, nuclei, and lysosomes) at ≥ 10 -1 μM levels. Last, we examined a mixture of all PYRs (ie, Σ individual EC 15 ) using MTT assays and subcellular analyses. Our findings indicate that C6 cells are responsive to nM levels of PYRs, suggesting that astroglial susceptibility may contribute to the low-dose neurological effects caused by these insecticides. This research further suggests that C6 cells may provide relevant information as a screening platform for pesticide mixtures targeting nervous system cells by expected and unexpected toxicogenic pathways potentially contributing to clinical neurotoxicity. © The Author 2016. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Studying Coxiella burnetii Type IV Substrates in the Yeast Saccharomyces cerevisiae: Focus on Subcellular Localization and Protein Aggregation

PubMed Central

Rodríguez-Escudero, María; Cid, Víctor J.; Molina, María; Schulze-Luehrmann, Jan; Lührmann, Anja; Rodríguez-Escudero, Isabel

2016-01-01

Coxiella burnetii is a Gram-negative obligate parasitic bacterium that causes the disease Q-fever in humans. To establish its intracellular niche, it utilizes the Icm/Dot type IVB secretion system (T4BSS) to inject protein effectors into the host cell cytoplasm. The host targets of most cognate and candidate T4BSS-translocated effectors remain obscure. We used the yeast Saccharomyces cerevisiae as a model to express and study six C. burnetii effectors, namely AnkA, AnkB, AnkF, CBU0077, CaeA and CaeB, in search for clues about their role in C. burnetii virulence. When ectopically expressed in HeLa cells, these effectors displayed distinct subcellular localizations. Accordingly, GFP fusions of these proteins produced in yeast also decorated distinct compartments, and most of them altered cell growth. CaeA was ubiquitinated both in yeast and mammalian cells and, in S. cerevisiae, accumulated at juxtanuclear quality-control compartments (JUNQs) and insoluble protein deposits (IPODs), characteristic of aggregative or misfolded proteins. AnkA, which was not ubiquitinated, accumulated exclusively at the IPOD. CaeA, but not AnkA or the other effectors, caused oxidative damage in yeast. We discuss that CaeA and AnkA behavior in yeast may rather reflect misfolding than recognition of conserved targets in the heterologous system. In contrast, CBU0077 accumulated at vacuolar membranes and abnormal ER extensions, suggesting that it interferes with vesicular traffic, whereas AnkB associated with the yeast nucleolus. Both effectors shared common localization features in HeLa and yeast cells. Our results support the idea that C. burnetii T4BSS effectors manipulate multiple host cell targets, which can be conserved in higher and lower eukaryotic cells. However, the behavior of CaeA and AnkA prompt us to conclude that heterologous protein aggregation and proteostatic stress can be a limitation to be considered when using the yeast model to assess the function of bacterial effectors. PMID:26821324

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pestov, Nikolay B., E-mail: korn@mail.ibch.ru; Dmitriev, Ruslan I.; Kostina, Maria B.

Highlights: Black-Right-Pointing-Pointer Full-length secretory pathway Ca-ATPase (SPCA2) cloned from rat duodenum. Black-Right-Pointing-Pointer ATP2C2 gene (encoding SPCA2) exists only in genomes of Tetrapoda. Black-Right-Pointing-Pointer Rat and pig SPCA2 are expressed in intestines, lung and some secretory glands. Black-Right-Pointing-Pointer Subcellular localization of SPCA2 may depend on tissue type. Black-Right-Pointing-Pointer In rat duodenum, SPCA2 is localized in plasma membrane-associated compartments. -- Abstract: Secretory pathway Ca-ATPases are less characterized mammalian calcium pumps than plasma membrane Ca-ATPases and sarco-endoplasmic reticulum Ca-ATPases. Here we report analysis of molecular evolution, alternative splicing, tissue-specific expression and subcellular localization of the second isoform of the secretory pathway Ca-ATPase (SPCA2),more » the product of the ATP2C2 gene. The primary structure of SPCA2 from rat duodenum deduced from full-length transcript contains 944 amino acid residues, and exhibits 65% sequence identity with known SPCA1. The rat SPCA2 sequence is also highly homologous to putative human protein KIAA0703, however, the latter seems to have an aberrant N-terminus originating from intron 2. The tissue-specificity of SPCA2 expression is different from ubiquitous SPCA1. Rat SPCA2 transcripts were detected predominantly in gastrointestinal tract, lung, trachea, lactating mammary gland, skin and preputial gland. In the newborn pig, the expression profile is very similar with one remarkable exception: porcine bulbourethral gland gave the strongest signal. Upon overexpression in cultured cells, SPCA2 shows an intracellular distribution with remarkable enrichment in Golgi. However, in vivo SPCA2 may be localized in compartments that differ among various tissues: it is intracellular in epidermis, but enriched in plasma membranes of the intestinal epithelium. Analysis of SPCA2 sequences from various vertebrate species argue that ATP2C2 gene radiated from ATP2C1 (encoding SPCA1) during adaptation of tetrapod ancestors to terrestrial habitats.« less

Appropriate sampling strategy and analytical methodology to address contamination by industry. Part 2: Geochemistry and speciation analysis

NASA Astrophysics Data System (ADS)

Shtiza, Aurela; Swennen, Rudy

2011-03-01

The degree of contamination in soils, sediments and dusts can be assessed based on knowledge of a variety of factors, such as industrialization, type of contaminants, deposition conditions, contamination-control techniques, along with the characteristics of the recipient environmental compartments, which include pathways for contamination transport, depth of infiltration, and degree of groundwater contamination. The impact of contaminants also depends on the quantity, mobility and speciation of contaminants/wastes as well as on the sensitivity of the recipient compartments. With sufficient knowledge of these factors, a number of conclusions can be drawn concerning the status of contamination in industrialized areas. This literature review aims to scrutinize some of the methods used to analyse the occurrence, speciation, mobility, bioavailability and likely the toxic effects of contaminants in the environment.

Assimilation and subcellular partitioning of elements by grass shrimp collected along an impact gradient.

PubMed

Seebaugh, David R; Wallace, William G

2009-06-28

Chronic exposure to polluted field conditions can impact metal bioavailability in prey and may influence metal transfer to predators. The present study investigated the assimilation of Cd, Hg and organic carbon by grass shrimp Palaemonetes pugio, collected along an impact gradient within the New York/New Jersey Harbor Estuary. Adult shrimp were collected from five Staten Island, New York study sites, fed (109)Cd- or (203)Hg-labeled amphipods or (14)C-labeled meals and analyzed for assimilation efficiencies (AE). Subsamples of amphipods and shrimp were subjected to subcellular fractionation to isolate metal associated with a compartment presumed to contain trophically available metal (TAM) (metal associated with heat-stable proteins [HSP - e.g., metallothionein-like proteins], heat-denatured proteins [HDP - e.g., enzymes] and organelles [ORG]). TAM-(109)Cd% and TAM-(203)Hg% in radiolabeled amphipods were approximately 64% and approximately 73%, respectively. Gradients in AE-(109)Cd% ( approximately 54% to approximately 75%) and AE-(203)Hg% ( approximately 61% to approximately 78%) were observed for grass shrimp, with the highest values exhibited by shrimp collected from sites within the heavily polluted Arthur Kill complex. Population differences in AE-(14)C% were not observed. Assimilated (109)Cd% partitioned to the TAM compartment in grass shrimp varied between approximately 67% and approximately 75%. (109)Cd bound to HSP in shrimp varied between approximately 15% and approximately 47%, while (109)Cd associated with metal-sensitive HDP was approximately 17% to approximately 44%. Percentages of assimilated (109)Cd bound to ORG were constant at approximately 10%. Assimilated (203)Hg% associated with TAM in grass shrimp did not exhibit significant variation. Percentages of assimilated (203)Hg bound to HDP ( approximately 47%) and ORG ( approximately 11%) did not vary among populations and partitioning of (203)Hg to HSP was not observed. Using a simplified biokinetic model of metal accumulation from the diet, it is estimated that site-specific variability in Cd AE by shrimp and tissue Cd burdens in field-collected prey (polychaetes Nereis spp.) could potentially result in up to approximately 3.2-fold differences in the dose of Cd assimilated by shrimp from a meal in the field. The results of this study also suggest that chronic field exposure can impact mechanisms of metal transport across the gut epithelium that do not influence carbon assimilation. Differences in the assimilation and subcellular partitioning of metal may have important implications for metal toxicity in impacted shrimp populations.

Intracellular pH (pHin) and cytosolic calcium ([Ca2+]cyt) regulation via ATPases: studies in cell populations, single cells, and subcellular compartments

NASA Astrophysics Data System (ADS)

Rojas, Jose D.; Sanka, Shankar C.; Gyorke, Sandor; Wesson, Donald E.; Minta, Akwasi; Martinez-Zaguilan, Raul

1999-07-01

Changes in pHin and (Ca2+)cyt are important in the signal transduction mechanisms leading to many physiological responses including cell growth, motility, secretion/exocytosis, etc. The concentrations of these ions are regulated via primary and secondary ion transporting mechanisms. In diabetes, specific pH and Ca2+ regulatory mechanism might be altered. To study these ions, we employ fluorescence spectroscopy, and cell imagin spectroscopy/confocal microscopy. pH and Ca2+ indicators are loaded in the cytosol with acetoxymethyl ester forms of dyes, and in endosomal/lysosomal (E/L) compartments by overnight incubation of cells with dextran- conjugated ion fluorescent probes. We focus on specific pH and Ca2+ regulatory systems: plasmalemmal vacuolar- type H+-ATPases (pm V-ATPases) and sarcoplasmic/endoplasmic reticulum Ca2+-ATPases (SERCA). As experimental models, we employ vascular smooth muscle (VSM) and microvascular endothelial cells. We have chosen these cells because they are important in blood flow regulation and in angiogenesis. These processes are altered in diabetes. In many cell types, ion transport processes are dependent on metabolism of glucose for maximal activity. Our main findings are: (a) glycolysis coupling the activity of SERCA is required for cytosolic Ca2+ homeostasis in both VSM and microvascular endothelial cells; (b) E/L compartments are important for pH and Ca2+ regulation via H+-ATPases and SERCA, respectively; and (c) pm-V- ATPases are important for pHin regulation in microvascular endothelial cells.

Dynamic and nucleolin-dependent localization of human cytomegalovirus UL84 to the periphery of viral replication compartments and nucleoli.

PubMed

Bender, Brian J; Coen, Donald M; Strang, Blair L

2014-10-01

Protein-protein and protein-nucleic acid interactions within subcellular compartments are required for viral genome replication. To understand the localization of the human cytomegalovirus viral replication factor UL84 relative to other proteins involved in viral DNA synthesis and to replicating viral DNA in infected cells, we created a recombinant virus expressing a FLAG-tagged version of UL84 (UL84FLAG) and used this virus in immunofluorescence assays. UL84FLAG localization differed at early and late times of infection, transitioning from diffuse distribution throughout the nucleus to exclusion from the interior of replication compartments, with some concentration at the periphery of replication compartments with newly labeled DNA and the viral DNA polymerase subunit UL44. Early in infection, UL84FLAG colocalized with the viral single-stranded DNA binding protein UL57, but colocalization became less prominent as infection progressed. A portion of UL84FLAG also colocalized with the host nucleolar protein nucleolin at the peripheries of both replication compartments and nucleoli. Small interfering RNA (siRNA)-mediated knockdown of nucleolin resulted in a dramatic elimination of UL84FLAG from replication compartments and other parts of the nucleus and its accumulation in the cytoplasm. Reciprocal coimmunoprecipitation of viral proteins from infected cell lysates revealed association of UL84, UL44, and nucleolin. These results indicate that UL84 localization during infection is dynamic, which is likely relevant to its functions, and suggest that its nuclear and subnuclear localization is highly dependent on direct or indirect interactions with nucleolin. Importance: The protein-protein interactions among viral and cellular proteins required for replication of the human cytomegalovirus (HCMV) DNA genome are poorly understood. We sought to understand how an enigmatic HCMV protein critical for virus replication, UL84, localizes relative to other viral and cellular proteins required for HCMV genome replication and replicating viral DNA. We found that UL84 localizes with viral proteins, viral DNA, and the cellular nucleolar protein nucleolin in the subnuclear replication compartments in which viral DNA replication occurs. Unexpectedly, we also found localization of UL84 with nucleolin in nucleoli and showed that the presence of nucleolin is involved in localization of UL84 to the nucleus. These results add to previous work showing the importance of nucleolin in replication compartment architecture and viral DNA synthesis and are relevant to understanding UL84 function. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Redox Indicator Mice Stably Expressing Genetically Encoded Neuronal roGFP: Versatile Tools to Decipher Subcellular Redox Dynamics in Neuropathophysiology.

PubMed

Wagener, Kerstin C; Kolbrink, Benedikt; Dietrich, Katharina; Kizina, Kathrin M; Terwitte, Lukas S; Kempkes, Belinda; Bao, Guobin; Müller, Michael

2016-07-01

Reactive oxygen species (ROS) and downstream redox alterations not only mediate physiological signaling but also neuropathology. For long, ROS/redox imaging was hampered by a lack of reliable probes. Genetically encoded redox sensors overcame this gap and revolutionized (sub)cellular redox imaging. Yet, the successful delivery of sensor-coding DNA, which demands transfection/transduction of cultured preparations or stereotaxic microinjections of each subject, remains challenging. By generating transgenic mice, we aimed to overcome limiting cultured preparations, circumvent surgical interventions, and to extend effectively redox imaging to complex and adult preparations. Our redox indicator mice widely express Thy1-driven roGFP1 (reduction-oxidation-sensitive green fluorescent protein 1) in neuronal cytosol or mitochondria. Negative phenotypic effects of roGFP1 were excluded and its proper targeting and functionality confirmed. Redox mapping by ratiometric wide-field imaging reveals most oxidizing conditions in CA3 neurons. Furthermore, mitochondria are more oxidized than cytosol. Cytosolic and mitochondrial roGFP1s reliably report cell endogenous redox dynamics upon metabolic challenge or stimulation. Fluorescence lifetime imaging yields stable, but marginal, response ranges. We therefore developed automated excitation ratiometric 2-photon imaging. It offers superior sensitivity, spatial resolution, and response dynamics. Redox indicator mice enable quantitative analyses of subcellular redox dynamics in a multitude of preparations and at all postnatal stages. This will uncover cell- and compartment-specific cerebral redox signals and their defined alterations during development, maturation, and aging. Cross-breeding with other disease models will reveal molecular details on compartmental redox homeostasis in neuropathology. Combined with ratiometric 2-photon imaging, this will foster our mechanistic understanding of cellular redox signals in their full complexity. Antioxid. Redox Signal. 25, 41-58.

Thyroid states regulate subcellular glucose phosphorylation activity in male mice

PubMed Central

Martins Peçanha, Flavia Letícia; dos Santos, Reinaldo Sousa

2017-01-01

The thyroid hormones (THs), triiodothyronine (T3) and thyroxine (T4), are very important in organism metabolism and regulate glucose utilization. Hexokinase (HK) is responsible for the first step of glycolysis, catalyzing the conversion of glucose to glucose 6-phosphate. HK has been found in different cellular compartments, and new functions have been attributed to this enzyme. The effects of hyperthyroidism on subcellular glucose phosphorylation in mouse tissues were examined. Tissues were removed, subcellular fractions were isolated from eu- and hyperthyroid (T3, 0.25 µg/g, i.p. during 21 days) mice and HK activity was assayed. Glucose phosphorylation was increased in the particulate fraction in soleus (312.4% ± 67.1, n = 10), gastrocnemius (369.2% ± 112.4, n = 10) and heart (142.2% ± 13.6, n = 10) muscle in the hyperthyroid group compared to the control group. Hexokinase activity was not affected in brain or liver. No relevant changes were observed in HK activity in the soluble fraction for all tissues investigated. Acute T3 administration (single dose of T3, 1.25 µg/g, i.p.) did not modulate HK activity. Interestingly, HK mRNA levels remained unchanged and HK bound to mitochondria was increased by T3 treatment, suggesting a posttranscriptional mechanism. Analysis of the AKT pathway showed a 2.5-fold increase in AKT and GSK3B phosphorylation in the gastrocnemius muscle in the hyperthyroid group compared to the euthyroid group. Taken together, we show for the first time that THs modulate HK activity specifically in particulate fractions and that this action seems to be under the control of the AKT and GSK3B pathways. PMID:28483784

Dynamic Fluctuations in Subcellular Localization of the Hippo Pathway Effector Yorkie In Vivo.

PubMed

Manning, Samuel A; Dent, Lucas G; Kondo, Shu; Zhao, Ziqing W; Plachta, Nicolas; Harvey, Kieran F

2018-05-21

The Hippo pathway is an evolutionarily conserved signaling network that integrates diverse cues to control organ size and cell fate. The central downstream pathway protein in Drosophila is the transcriptional co-activator Yorkie (YAP and TAZ in humans), which regulates gene expression with the Scalloped/TEA domain family member (TEAD) transcription factors [1-8]. A central regulatory step in the Hippo pathway is phosphorylation of Yorkie by the NDR family kinase Warts, which promotes Yorkie cytoplasmic localization by stimulating association with 14-3-3 proteins [9-12]. Numerous reports have purported a static model of Hippo signaling whereby, upon Hippo activation, Yorkie/YAP/TAZ become cytoplasmic and therefore inactive, and upon Hippo repression, Yorkie/YAP/TAZ transit to the nucleus and are active. However, we have little appreciation for the dynamics of Yorkie/YAP/TAZ subcellular localization because most studies have been performed in fixed cells and tissues. To address this, we used live multiphoton microscopy to investigate the dynamics of an endogenously tagged Yorkie-Venus protein in growing epithelial organs. We found that the majority of Yorkie rapidly traffics between the cytoplasm and nucleus, rather than being statically localized in either compartment. In addition, discrete cell populations within the same organ display different rates of Yorkie nucleo-cytoplasmic shuttling. By assessing Yorkie dynamics in warts mutant tissue, we found that the Hippo pathway regulates Yorkie subcellular distribution by regulating its rate of nuclear import. Furthermore, Yorkie's localization fluctuates dramatically throughout the cell cycle, being predominantly cytoplasmic during interphase and, unexpectedly, chromatin enriched during mitosis. Yorkie's association with mitotic chromatin is Scalloped dependent, suggesting a potential role in mitotic bookmarking. Copyright © 2018 Elsevier Ltd. All rights reserved.

Accounting for Protein Subcellular Localization: A Compartmental Map of the Rat Liver Proteome*

PubMed Central

Jadot, Michel; Boonen, Marielle; Thirion, Jaqueline; Wang, Nan; Xing, Jinchuan; Zhao, Caifeng; Tannous, Abla; Qian, Meiqian; Zheng, Haiyan; Everett, John K.; Moore, Dirk F.; Sleat, David E.; Lobel, Peter

2017-01-01

Accurate knowledge of the intracellular location of proteins is important for numerous areas of biomedical research including assessing fidelity of putative protein-protein interactions, modeling cellular processes at a system-wide level and investigating metabolic and disease pathways. Many proteins have not been localized, or have been incompletely localized, partly because most studies do not account for entire subcellular distribution. Thus, proteins are frequently assigned to one organelle whereas a significant fraction may reside elsewhere. As a step toward a comprehensive cellular map, we used subcellular fractionation with classic balance sheet analysis and isobaric labeling/quantitative mass spectrometry to assign locations to >6000 rat liver proteins. We provide quantitative data and error estimates describing the distribution of each protein among the eight major cellular compartments: nucleus, mitochondria, lysosomes, peroxisomes, endoplasmic reticulum, Golgi, plasma membrane and cytosol. Accounting for total intracellular distribution improves quality of organelle assignments and assigns proteins with multiple locations. Protein assignments and supporting data are available online through the Prolocate website (http://prolocate.cabm.rutgers.edu). As an example of the utility of this data set, we have used organelle assignments to help analyze whole exome sequencing data from an infant dying at 6 months of age from a suspected neurodegenerative lysosomal storage disorder of unknown etiology. Sequencing data was prioritized using lists of lysosomal proteins comprising well-established residents of this organelle as well as novel candidates identified in this study. The latter included copper transporter 1, encoded by SLC31A1, which we localized to both the plasma membrane and lysosome. The patient harbors two predicted loss of function mutations in SLC31A1, suggesting that this may represent a heretofore undescribed recessive lysosomal storage disease gene. PMID:27923875

Accounting for Protein Subcellular Localization: A Compartmental Map of the Rat Liver Proteome.

PubMed

Jadot, Michel; Boonen, Marielle; Thirion, Jaqueline; Wang, Nan; Xing, Jinchuan; Zhao, Caifeng; Tannous, Abla; Qian, Meiqian; Zheng, Haiyan; Everett, John K; Moore, Dirk F; Sleat, David E; Lobel, Peter

2017-02-01

Accurate knowledge of the intracellular location of proteins is important for numerous areas of biomedical research including assessing fidelity of putative protein-protein interactions, modeling cellular processes at a system-wide level and investigating metabolic and disease pathways. Many proteins have not been localized, or have been incompletely localized, partly because most studies do not account for entire subcellular distribution. Thus, proteins are frequently assigned to one organelle whereas a significant fraction may reside elsewhere. As a step toward a comprehensive cellular map, we used subcellular fractionation with classic balance sheet analysis and isobaric labeling/quantitative mass spectrometry to assign locations to >6000 rat liver proteins. We provide quantitative data and error estimates describing the distribution of each protein among the eight major cellular compartments: nucleus, mitochondria, lysosomes, peroxisomes, endoplasmic reticulum, Golgi, plasma membrane and cytosol. Accounting for total intracellular distribution improves quality of organelle assignments and assigns proteins with multiple locations. Protein assignments and supporting data are available online through the Prolocate website (http://prolocate.cabm.rutgers.edu). As an example of the utility of this data set, we have used organelle assignments to help analyze whole exome sequencing data from an infant dying at 6 months of age from a suspected neurodegenerative lysosomal storage disorder of unknown etiology. Sequencing data was prioritized using lists of lysosomal proteins comprising well-established residents of this organelle as well as novel candidates identified in this study. The latter included copper transporter 1, encoded by SLC31A1, which we localized to both the plasma membrane and lysosome. The patient harbors two predicted loss of function mutations in SLC31A1, suggesting that this may represent a heretofore undescribed recessive lysosomal storage disease gene. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Redox Indicator Mice Stably Expressing Genetically Encoded Neuronal roGFP: Versatile Tools to Decipher Subcellular Redox Dynamics in Neuropathophysiology

PubMed Central

Wagener, Kerstin C.; Kolbrink, Benedikt; Dietrich, Katharina; Kizina, Kathrin M.; Terwitte, Lukas S.; Kempkes, Belinda; Bao, Guobin

2016-01-01

Abstract Aims: Reactive oxygen species (ROS) and downstream redox alterations not only mediate physiological signaling but also neuropathology. For long, ROS/redox imaging was hampered by a lack of reliable probes. Genetically encoded redox sensors overcame this gap and revolutionized (sub)cellular redox imaging. Yet, the successful delivery of sensor-coding DNA, which demands transfection/transduction of cultured preparations or stereotaxic microinjections of each subject, remains challenging. By generating transgenic mice, we aimed to overcome limiting cultured preparations, circumvent surgical interventions, and to extend effectively redox imaging to complex and adult preparations. Results: Our redox indicator mice widely express Thy1-driven roGFP1 (reduction–oxidation-sensitive green fluorescent protein 1) in neuronal cytosol or mitochondria. Negative phenotypic effects of roGFP1 were excluded and its proper targeting and functionality confirmed. Redox mapping by ratiometric wide-field imaging reveals most oxidizing conditions in CA3 neurons. Furthermore, mitochondria are more oxidized than cytosol. Cytosolic and mitochondrial roGFP1s reliably report cell endogenous redox dynamics upon metabolic challenge or stimulation. Fluorescence lifetime imaging yields stable, but marginal, response ranges. We therefore developed automated excitation ratiometric 2-photon imaging. It offers superior sensitivity, spatial resolution, and response dynamics. Innovation and Conclusion: Redox indicator mice enable quantitative analyses of subcellular redox dynamics in a multitude of preparations and at all postnatal stages. This will uncover cell- and compartment-specific cerebral redox signals and their defined alterations during development, maturation, and aging. Cross-breeding with other disease models will reveal molecular details on compartmental redox homeostasis in neuropathology. Combined with ratiometric 2-photon imaging, this will foster our mechanistic understanding of cellular redox signals in their full complexity. Antioxid. Redox Signal. 25, 41–58. PMID:27059697

Genetic disorders of vitamin B12 metabolism: eight complementation groups – eight genes

PubMed Central

Froese, D. Sean; Gravel, Roy A.

2010-01-01

Vitamin B12 (cobalamin, Cbl) is an essential nutrient in human metabolism. Genetic diseases of vitamin B12 utilisation constitute an important fraction of inherited newborn disease. Functionally, B12 is the cofactor for methionine synthase and methylmalonyl CoA mutase. To function as a cofactor, B12 must be metabolised through a complex pathway that modifies its structure and takes it through subcellular compartments of the cell. Through the study of inherited disorders of vitamin B12 utilisation, the genes for eight complementation groups have been identified, leading to the determination of the general structure of vitamin B12 processing and providing methods for carrier testing, prenatal diagnosis and approaches to treatment. PMID:21114891

Proteomics profiling of interactome dynamics by colocalisation analysis (COLA)† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6mb00701e Click here for additional data file. Click here for additional data file.

PubMed Central

Sailem, Heba Z.; Kümper, Sandra; Tape, Christopher J.; McCully, Ryan R.; Paul, Angela; Anjomani-Virmouni, Sara; Jørgensen, Claus; Poulogiannis, George; Marshall, Christopher J.

2017-01-01

Localisation and protein function are intimately linked in eukaryotes, as proteins are localised to specific compartments where they come into proximity of other functionally relevant proteins. Significant co-localisation of two proteins can therefore be indicative of their functional association. We here present COLA, a proteomics based strategy coupled with a bioinformatics framework to detect protein–protein co-localisations on a global scale. COLA reveals functional interactions by matching proteins with significant similarity in their subcellular localisation signatures. The rapid nature of COLA allows mapping of interactome dynamics across different conditions or treatments with high precision. PMID:27824369

Protein Kinases and Phosphatases in the Control of Cell Fate

PubMed Central

Bononi, Angela; Agnoletto, Chiara; De Marchi, Elena; Marchi, Saverio; Patergnani, Simone; Bonora, Massimo; Giorgi, Carlotta; Missiroli, Sonia; Poletti, Federica; Rimessi, Alessandro; Pinton, Paolo

2011-01-01

Protein phosphorylation controls many aspects of cell fate and is often deregulated in pathological conditions. Several recent findings have provided an intriguing insight into the spatial regulation of protein phosphorylation across different subcellular compartments and how this can be finely orchestrated by specific kinases and phosphatases. In this review, the focus will be placed on (i) the phosphoinositide 3-kinase (PI3K) pathway, specifically on the kinases Akt and mTOR and on the phosphatases PP2a and PTEN, and on (ii) the PKC family of serine/threonine kinases. We will look at general aspects of cell physiology controlled by these kinases and phosphatases, highlighting the signalling pathways that drive cell division, proliferation, and apoptosis. PMID:21904669

Imaging intraflagellar transport in mammalian primary cilia.

PubMed

Besschetnova, Tatiana Y; Roy, Barnali; Shah, Jagesh V

2009-01-01

The primary cilium is a specialized organelle that projects from the surface of many cell types. Unlike its motile counterpart it cannot beat but does transduce extracellular stimuli into intracellular signals and acts as a specialized subcellular compartment. The cilium is built and maintained by the transport of proteins and other biomolecules into and out of this compartment. The trafficking machinery for the cilium is referred to as IFT or intraflagellar transport. It was originally identified in the green algae Chlamydomonas and has been discovered throughout the evolutionary tree. The IFT machinery is widely conserved and acts to establish, maintain, and disassemble cilia and flagella. Understanding the role of IFT in cilium signaling and regulation requires a methodology for observing it directly. Here we describe current methods for observing the IFT process in mammalian primary cilia through the generation of fluorescent protein fusions and their expression in ciliated cell lines. The observation protocol uses high-resolution time-lapse microscopy to provide detailed quantitative measurements of IFT particle velocities in wild-type cells or in the context of genetic or other perturbations. Direct observation of IFT trafficking will provide a unique tool to dissect the processes that govern cilium regulation and signaling. 2009 Elsevier Inc. All rights reserved.

Roles of the nucleolus in the CAG RNA-mediated toxicity.

PubMed

Tsoi, Ho; Chan, Ho Yin Edwin

2014-06-01

The nucleolus is a subnuclear compartment within the cell nucleus that serves as the site for ribosomal RNA (rRNA) transcription and the assembly of ribosome subunits. Apart from its classical role in ribosomal biogenesis, a number of cellular regulatory roles have recently been assigned to the nucleolus, including governing the induction of apoptosis. "Nucleolar stress" is a term that is used to describe a signaling pathway through which the nucleolus communicates with other subcellular compartments, including the mitochondria, to induce apoptosis. It is an effective mechanism for eliminating cells that are incapable of performing protein synthesis efficiently due to ribosome biogenesis defects. The down-regulation of rRNA transcription is a common cause of nucleolar function disruption that subsequently triggers nucleolar stress, and has been associated with the pathogenesis of neurological disorders such as spinocerebellar ataxias (SCAs) and Huntington's diseases (HD). This article discusses recent advances in mechanistic studies of how expanded CAG trinucleotide repeat RNA transcripts trigger nucleolar stress in SCAs, HD and other trinucleotide repeat disorders. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease. Copyright © 2013 Elsevier B.V. All rights reserved.

Reactive Oxygen Species in Metabolic and Inflammatory Signaling.

PubMed

Forrester, Steven J; Kikuchi, Daniel S; Hernandes, Marina S; Xu, Qian; Griendling, Kathy K

2018-03-16

Reactive oxygen species (ROS) are well known for their role in mediating both physiological and pathophysiological signal transduction. Enzymes and subcellular compartments that typically produce ROS are associated with metabolic regulation, and diseases associated with metabolic dysfunction may be influenced by changes in redox balance. In this review, we summarize the current literature surrounding ROS and their role in metabolic and inflammatory regulation, focusing on ROS signal transduction and its relationship to disease progression. In particular, we examine ROS production in compartments such as the cytoplasm, mitochondria, peroxisome, and endoplasmic reticulum and discuss how ROS influence metabolic processes such as proteasome function, autophagy, and general inflammatory signaling. We also summarize and highlight the role of ROS in the regulation metabolic/inflammatory diseases including atherosclerosis, diabetes mellitus, and stroke. In order to develop therapies that target oxidative signaling, it is vital to understand the balance ROS signaling plays in both physiology and pathophysiology, and how manipulation of this balance and the identity of the ROS may influence cellular and tissue homeostasis. An increased understanding of specific sources of ROS production and an appreciation for how ROS influence cellular metabolism may help guide us in the effort to treat cardiovascular diseases. © 2018 American Heart Association, Inc.

Surface-charge-dependent cell localization and cytotoxicity of cerium oxide nanoparticles.

PubMed

Asati, Atul; Santra, Santimukul; Kaittanis, Charalambos; Perez, J Manuel

2010-09-28

Cerium oxide nanoparticles (nanoceria) have shown great potential as antioxidant and radioprotective agents for applications in cancer therapy. Recently, various polymer-coated nanoceria preparations have been developed to improve their aqueous solubility and allow for surface functionalization of these nanoparticles. However, the interaction of polymer-coated nanoceria with cells, their uptake mechanism, and subcellular localization are poorly understood. Herein, we engineered polymer-coated cerium oxide nanoparticles with different surface charges (positive, negative, and neutral) and studied their internalization and toxicity in normal and cancer cell lines. The results showed that nanoceria with a positive or neutral charge enters most of the cell lines studied, while nanoceria with a negative charge internalizes mostly in the cancer cell lines. Moreover, upon entry into the cells, nanoceria is localized to different cell compartments (e.g., cytoplasm and lysosomes) depending on the nanoparticle's surface charge. The internalization and subcellular localization of nanoceria plays a key role in the nanoparticles' cytotoxicity profile, exhibiting significant toxicity when they localize in the lysosomes of the cancer cells. In contrast, minimal toxicity is observed when they localize into the cytoplasm or do not enter the cells. Taken together, these results indicate that the differential surface-charge-dependent localization of nanoceria in normal and cancer cells plays a critical role in the nanoparticles' toxicity profile.

Extrasynaptic N-methyl-D-aspartate (NMDA) receptor stimulation induces cytoplasmic translocation of the CDKL5 kinase and its proteasomal degradation.

PubMed

Rusconi, Laura; Kilstrup-Nielsen, Charlotte; Landsberger, Nicoletta

2011-10-21

Mutations in the X-linked gene cyclin-dependent kinase-like 5 (CDKL5) have been found in patients with epileptic encephalopathy characterized by early onset intractable epilepsy, including infantile spasms and other types of seizures, severe developmental delay, and often the development of Rett syndrome-like features. Despite its clear involvement in proper brain development, CDKL5 functions are still far from being understood. In this study, we analyzed the subcellular localization of the endogenous kinase in primary murine hippocampal neurons. CDKL5 was localized both in nucleus and cytoplasm and, conversely to proliferating cells, did not undergo constitutive shuttling between these compartments. Nevertheless, glutamate stimulation was able to induce the exit of the kinase from the nucleus and its subsequent accumulation in the perinuclear cytoplasm. Moreover, we found that sustained glutamate stimulation promoted CDKL5 proteasomal degradation. Both events were mediated by the specific activation of extrasynaptic pool of N-methyl-d-aspartate receptors. Proteasomal degradation was also induced by withdrawal of neurotrophic factors and hydrogen peroxide treatment, two different paradigms of cell death. Altogether, our results indicate that both subcellular localization and expression of CDKL5 are modulated by the activation of extrasynaptic N-methyl-D-aspartate receptors and suggest regulation of CDKL5 by cell death pathways.

Src-family Tyrosine Kinases in Oogenesis, Oocyte Maturation, and Fertilization: An Evolutionary Perspective

PubMed Central

Kinsey, William H.

2015-01-01

The oocyte is a highly specialized cell poised to respond to fertilization with a unique set of actions needed to recognize and incorporate a single sperm, complete meiosis, reprogram maternal and paternal genomes and assemble them into a unique zygotic genome, and finally initiate the mitotic cell cycle. Oocytes accomplish this diverse series of events through an array of signal transduction pathway components that include a characteristic collection of protein tyrosine kinases. The src-family protein kinases figure importantly in this signaling array and oocytes characteristically express certain SFKs at high levels to provide for the unique actions that the oocyte must perform. The SFKs typically exhibit a distinct pattern of subcellular localization in oocytes and perform critical functions in different subcellular compartments at different steps during oocyte maturation and fertilization. While many aspects of SFK signaling are conserved among oocytes from different species, significant differences exist in the extent to which src-family -mediated pathways are used by oocytes from species that fertilize externally vs those which are fertilized internally. The observation that several oocyte functions which require SFK signaling appear to represent common points of failure during assisted reproductive techniques in humans, highlights the importance of these signaling pathways for human reproductive health. PMID:25030759

Multiclassifier combinatorial proteomics of organelle shadows at the example of mitochondria in chromatin data.

PubMed

Kustatscher, Georg; Grabowski, Piotr; Rappsilber, Juri

2016-02-01

Subcellular localization is an important aspect of protein function, but the protein composition of many intracellular compartments is poorly characterized. For example, many nuclear bodies are challenging to isolate biochemically and thus remain inaccessible to proteomics. Here, we explore covariation in proteomics data as an alternative route to subcellular proteomes. Rather than targeting a structure of interest biochemically, we target it by machine learning. This becomes possible by taking data obtained for one organelle and searching it for traces of another organelle. As an extreme example and proof-of-concept we predict mitochondrial proteins based on their covariation in published interphase chromatin data. We detect about ⅓ of the known mitochondrial proteins in our chromatin data, presumably most as contaminants. However, these proteins are not present at random. We show covariation of mitochondrial proteins in chromatin proteomics data. We then exploit this covariation by multiclassifier combinatorial proteomics to define a list of mitochondrial proteins. This list agrees well with different databases on mitochondrial composition. This benchmark test raises the possibility that, in principle, covariation proteomics may also be applicable to structures for which no biochemical isolation procedures are available. © 2015 The Authors. Proteomics Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nonreceptor Protein-Tyrosine Kinases in Neutrophil Activation

PubMed

Welch; Mauran; Maridonneau-Parini

1996-06-01

Nonreceptor protein-tyrosine kinases are involved in the regulation of almost all neutrophil responses such as adhesion, chemotaxis, priming, oxidative burst, and degranulation. Here, we show that phagocytosis is also regulated by protein-tyrosine kinase activity. Using various protein-tyrosine kinase inhibitors, we further demonstrate that opsonized zymosan-induced degranulation of specific and azurophil granules is regulated by protein-tyrosine kinase activity, whereas phorbol ester-induced degranulation is not. Several of the nonreceptor protein-tyrosine kinases involving in neutrophil signal transduction are known, including Fgr, Hck, Lyn, Yes, and Syk. Among these, Hck and Fgr are localized on the azurophil and specific granules, suggesting the involvement of these two protein-tyrosine kinases in the regulation of degranulation. In this report, we characterize some of the molecular properties of Hck and Fgr. We discuss the methods generally used for the measurement of protein-tyrosine kinase activities in neutrophils highlighting precautions against proteolysis. In addition, we show that in subcellular fractions of retinoic acid-differentiated neutrophil-like NB4 cells, the 59- and 61-kDa forms of Hck are attached to the membranes of their respective compartments by different mechanisms. Finally, we discuss the functional roles of protein-tyrosine kinases in the regulation of neutrophil activation and speculate on the importance of their subcellular localization.

Analysis of doxorubicin distribution in MCF-7 cells treated with drug-loaded nanoparticles by combination of two fluorescence-based techniques, confocal spectral imaging and capillary electrophoresis.

PubMed

Gautier, Juliette; Munnier, Emilie; Soucé, Martin; Chourpa, Igor; Douziech Eyrolles, Laurence

2015-05-01

The intracellular distribution of the antiancer drug doxorubicin (DOX) was followed qualitatively by fluorescence confocal spectral imaging (FCSI) and quantitatively by capillary electrophoresis (CE). FCSI permits the localization of the major fluorescent species in cell compartments, with spectral shifts indicating the polarity of the respective environment. However, distinction between drug and metabolites by FCSI is difficult due to their similar fluorochromes, and direct quantification of their fluorescence is complicated by quantum yield variation between different subcellular environments. On the other hand, capillary electrophoresis with fluorescence detection (CE-LIF) is a quantitative method capable of separating doxorubicin and its metabolites. In this paper, we propose a method for determining drug and metabolite concentration in enriched nuclear and cytosolic fractions of cancer cells by CE-LIF, and we compare these data with those of FCSI. Significant differences in the subcellular distribution of DOX are observed between the drug administered as a molecular solution or as a suspension of drug-loaded iron oxide nanoparticles coated with polyethylene glycol. Comparative analysis of the CE-LIF vs FCSI data may lead to a tentative calibration of this latter method in terms of DOX fluorescence quantum yields in the nucleus and more or less polar regions of the cytosol.

Efficient Cisplatin Pro-Drug Delivery Visualized with Sub-100 nm Resolution: Interfacing Engineered Thermosensitive Magnetomicelles with a Living System

DOE PAGES

Vitol, Elina A.; Rozhkova, Elena A.; Rose, Volker; ...

2014-06-06

Temperature-responsive magnetic nanomicelles can serve as thermal energy and cargo carriers with controlled drug release functionality. In view of their potential biomedical applications, understanding the modes of interaction between nanomaterials and living systems and evaluation of efficiency of cargo delivery is of the utmost importance. In this paper, we investigate the interaction between the hybrid magnetic nanomicelles engineered for controlled platinum complex drug delivery and a biological system at three fundamental levels: subcellular compartments, a single cell and whole living animal. Nanomicelles with polymeric P(NIPAAm-co-AAm)-b-PCL core-shell were loaded with a hydrophobic Pt(IV) complex and Fe 3O 4 nanoparticles though self-assembly.more » The distribution of a platinum complex on subcellular level is visualized using hard X-ray fluorescence microscopy with unprecedented level of detail at sub-100 nm spatial resolution. We then study the cytotoxic effects of platinum complex-loaded micelles in vitro on a head and neck cancer cell culture model SQ20B. In conclusion, by employing the magnetic functionality of the micelles and additionally loading them with a near infrared fluorescent dye, we magnetically target them to a tumor site in a live animal xenografted model which allows to visualize their biodistribution in vivo.« less

Enhanced pyruvate production in Candida glabrata by carrier engineering.

PubMed

Luo, Zhengshan; Liu, Song; Du, Guocheng; Xu, Sha; Zhou, Jingwen; Chen, Jian

2018-02-01

Pyruvate is an important organic acid that plays a key role in the central metabolic pathway. Manipulating transporters is an efficient strategy to enhance production of target organic acids and a means to understand the effects of altered intracellular pyruvate content on global metabolic networks. Efforts have been made to manipulate mitochondrial pyruvate carrier (MPC) to transport pyruvate into different subcellular compartments in Candida glabrata to demonstrate the effects of the subcellular distribution of pyruvate on central carbon metabolism. By increasing the mitochondrial pyruvate content through enhancing the rate of pyruvate transport into mitochondria, a high central carbon metabolism rate, specific growth rate and specific pyruvate production rate were obtained. Comparing the intracellular pyruvate content of engineered and control strains showed that higher intracellular pyruvate levels were not conducive to improving pyruvate productivity or central carbon metabolism. Plasma membrane expression of MPCs significantly increased the expression levels of key rate-limiting glycolytic enzymes. Moreover, pyruvate production of CGΔura3-Sp-MPC1, CGΔura3-Sp-MPC2, and CGΔura3-Sp-MPC1-Sp-MPC2 increased 134.4%, 120.3%, and 30.0%, respectively. In conclusion, lower intracellular pyruvate content enhanced central carbon metabolism and provided useful clues for improving the production of other organic acids in microorganisms. © 2017 Wiley Periodicals, Inc.

Subcellular Fractionation and Localization Studies Reveal a Direct Interaction of the Fragile X Mental Retardation Protein (FMRP) with Nucleolin

PubMed Central

Taha, Mohamed S.; Nouri, Kazem; Milroy, Lech G.; Moll, Jens M.; Herrmann, Christian; Brunsveld, Luc; Piekorz, Roland P.; Ahmadian, Mohammad R.

2014-01-01

Fragile X mental Retardation Protein (FMRP) is a well-known regulator of local translation of its mRNA targets in neurons. However, despite its ubiquitous expression, the role of FMRP remains ill-defined in other cell types. In this study we investigated the subcellular distribution of FMRP and its protein complexes in HeLa cells using confocal imaging as well as detergent-free fractionation and size exclusion protocols. We found FMRP localized exclusively to solid compartments, including cytosolic heavy and light membranes, mitochondria, nuclear membrane and nucleoli. Interestingly, FMRP was associated with nucleolin in both a high molecular weight ribosomal and translation-associated complex (≥6 MDa) in the cytosol, and a low molecular weight complex (∼200 kDa) in the nucleoli. Consistently, we identified two functional nucleolar localization signals (NoLSs) in FMRP that are responsible for a strong nucleolar colocalization of the C-terminus of FMRP with nucleolin, and a direct interaction of the N-terminus of FMRP with the arginine-glycine-glycine (RGG) domain of nucleolin. Taken together, we propose a novel mechanism by which a transient nucleolar localization of FMRP underlies a strong nucleocytoplasmic translocation, most likely in a complex with nucleolin and possibly ribosomes, in order to regulate translation of its target mRNAs. PMID:24658146

Role of regulatory subunits and protein kinase inhibitor (PKI) in determining nuclear localization and activity of the catalytic subunit of protein kinase A.

PubMed

Wiley, J C; Wailes, L A; Idzerda, R L; McKnight, G S

1999-03-05

Regulation of protein kinase A by subcellular localization may be critical to target catalytic subunits to specific substrates. We employed epitope-tagged catalytic subunit to correlate subcellular localization and gene-inducing activity in the presence of regulatory subunit or protein kinase inhibitor (PKI). Transiently expressed catalytic subunit distributed throughout the cell and induced gene expression. Co-expression of regulatory subunit or PKI blocked gene induction and prevented nuclear accumulation. A mutant PKI lacking the nuclear export signal blocked gene induction but not nuclear accumulation, demonstrating that nuclear export is not essential to inhibit gene induction. When the catalytic subunit was targeted to the nucleus with a nuclear localization signal, it was not sequestered in the cytoplasm by regulatory subunit, although its activity was completely inhibited. PKI redistributed the nuclear catalytic subunit to the cytoplasm and blocked gene induction, demonstrating that the nuclear export signal of PKI can override a strong nuclear localization signal. With increasing PKI, the export process appeared to saturate, resulting in the return of catalytic subunit to the nucleus. These results demonstrate that both the regulatory subunit and PKI are able to completely inhibit the gene-inducing activity of the catalytic subunit even when the catalytic subunit is forced to concentrate in the nuclear compartment.

Average oxidation state of carbon in proteins

PubMed Central

Dick, Jeffrey M.

2014-01-01

The formal oxidation state of carbon atoms in organic molecules depends on the covalent structure. In proteins, the average oxidation state of carbon (ZC) can be calculated as an elemental ratio from the chemical formula. To investigate oxidation–reduction (redox) patterns, groups of proteins from different subcellular locations and phylogenetic groups were selected for comparison. Extracellular proteins of yeast have a relatively high oxidation state of carbon, corresponding with oxidizing conditions outside of the cell. However, an inverse relationship between ZC and redox potential occurs between the endoplasmic reticulum and cytoplasm. This trend provides support for the hypothesis that protein transport and turnover are ultimately coupled to the maintenance of different glutathione redox potentials in subcellular compartments. There are broad changes in ZC in whole-genome protein compositions in microbes from different environments, and in Rubisco homologues, lower ZC tends to occur in organisms with higher optimal growth temperature. Energetic costs calculated from thermodynamic models are consistent with the notion that thermophilic organisms exhibit molecular adaptation to not only high temperature but also the reducing nature of many hydrothermal fluids. Further characterization of the material requirements of protein metabolism in terms of the chemical conditions of cells and environments may help to reveal other linkages among biochemical processes with implications for changes on evolutionary time scales. PMID:25165594

Divergent lactate dehydrogenase isoenzyme profile in cellular compartments of primate forebrain structures.

PubMed

Duka, Tetyana; Collins, Zachary; Anderson, Sarah M; Raghanti, Mary Ann; Ely, John J; Hof, Patrick R; Wildman, Derek E; Goodman, Morris; Grossman, Lawrence I; Sherwood, Chet C

2017-07-01

The compartmentalization and association of lactate dehydrogenase (LDH) with specific cellular structures (e.g., synaptosomal, sarcoplasmic or mitochondrial) may play an important role in brain energy metabolism. Our previous research revealed that LDH in the synaptosomal fraction shifts toward the aerobic isoforms (LDH-B) among the large-brained haplorhine primates compared to strepsirrhines. Here, we further analyzed the subcellular localization of LDH in primate forebrain structures using quantitative Western blotting and ELISA. We show that, in cytosolic and mitochondrial subfractions, LDH-B expression level was relatively elevated and LDH-A declined in haplorhines compared to strepsirrhines. LDH-B expression in mitochondrial fractions of the neocortex was preferentially increased, showing a particularly significant rise in the ratio of LDH-B to LDH-A in chimpanzees and humans. We also found a significant correlation between the protein levels of LDH-B in mitochondrial fractions from haplorhine neocortex and the synaptosomal LDH-B that suggests LDH isoforms shift from a predominance of A-subunits toward B-subunits as part of a system that spatially buffers dynamic energy requirements of brain cells. Our results indicate that there is differential subcellular compartmentalization of LDH isoenzymes that evolved among different primate lineages to meet the energy requirements in neocortical and striatal cells. Copyright © 2017 Elsevier Inc. All rights reserved.

The rough endoplasmatic reticulum is a central nucleation site of siRNA-mediated RNA silencing

PubMed Central

Stalder, Lukas; Heusermann, Wolf; Sokol, Lena; Trojer, Dominic; Wirz, Joel; Hean, Justin; Fritzsche, Anja; Aeschimann, Florian; Pfanzagl, Vera; Basselet, Pascal; Weiler, Jan; Hintersteiner, Martin; Morrissey, David V; Meisner-Kober, Nicole C

2013-01-01

Despite progress in mechanistic understanding of the RNA interference (RNAi) pathways, the subcellular sites of RNA silencing remain under debate. Here we show that loading of lipid-transfected siRNAs and endogenous microRNAs (miRNA) into RISC (RNA-induced silencing complexes), encounter of the target mRNA, and Ago2-mediated mRNA slicing in mammalian cells are nucleated at the rough endoplasmic reticulum (rER). Although the major RNAi pathway proteins are found in most subcellular compartments, the miRNA- and siRNA-loaded Ago2 populations co-sediment almost exclusively with the rER membranes, together with the RISC loading complex (RLC) factors Dicer, TAR RNA binding protein (TRBP) and protein activator of the interferon-induced protein kinase (PACT). Fractionation and membrane co-immune precipitations further confirm that siRNA-loaded Ago2 physically associates with the cytosolic side of the rER membrane. Additionally, RLC-associated double-stranded siRNA, diagnostic of RISC loading, and RISC-mediated mRNA cleavage products exclusively co-sediment with rER. Finally, we identify TRBP and PACT as key factors anchoring RISC to ER membranes in an RNA-independent manner. Together, our findings demonstrate that the outer rER membrane is a central nucleation site of siRNA-mediated RNA silencing. PMID:23511973

WE-AB-204-12: Dosimetry at the Sub-Cellular Scale of Auger-Electron Emitter 99m-Tc in a Mouse Single Thyroid Follicle Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taborda, A; Benabdallah, N; Desbree, A

2015-06-15

Purpose: To perform a dosimetry study at the sub-cellular scale of Auger-electron emitter 99m-Tc using a mouse single thyroid cellular model to investigate the contribution of the 99m-Tc Auger-electrons to the absorbed dose and possible link to the thyroid stunning in in vivo experiments in mice, recently reported in literature. Methods: The simulation of S-values for Auger-electron emitting radionuclides was performed using both the recent MCNP6 software and the Geant4-DNA extension of the Geant4 toolkit. The dosimetric calculations were validated through comparison with results from literature, using a simple model of a single cell consisting of two concentric spheres ofmore » unit density water and for six Auger-electron emitting radionuclides. Furthermore, the S-values were calculated using a single thyroid follicle model for uniformly distributed 123-I and 125-I radionuclides and compared with published S-values. After validation, the simulation of the S-values was performed for the 99m-Tc radionuclide within the several mouse thyroid follicle cellular compartments, considering the radiative and non-radiative transitions of the 99m-Tc radiation spectrum. Results: The calculated S-values using MCNP6 are in good agreement with the results from literature, validating its use for the 99m-Tc S-values calculations. The most significant absorbed dose corresponds to the case where the radionuclide is uniformly distributed in the follicular cell’s nucleus, with a S-value of 7.8 mGy/disintegration, due mainly to the absorbed Auger-electrons. The results show that, at a sub-cellular scale, the emitted X-rays and gamma particles do not contribute significantly to the absorbed dose. Conclusion: In this work, MCNP6 was validated for dosimetric studies at the sub-cellular scale. It was shown that the contribution of the Auger-electrons to the absorbed dose is important at this scale compared to the emitted photons’ contribution and can’t be neglected. The obtained S-values of Auger-electron emitting 99m-Tc radionuclide will be presented and discussed.« less

Determination of elemental distribution in green micro-algae using synchrotron radiation nano X-ray fluorescence (SR-nXRF) and electron microscopy techniques--subcellular localization and quantitative imaging of silver and cobalt uptake by Coccomyxa actinabiotis.

PubMed

Leonardo, T; Farhi, E; Boisson, A-M; Vial, J; Cloetens, P; Bohic, S; Rivasseau, C

2014-02-01

The newly discovered unicellular micro-alga Coccomyxa actinabiotis proves to be highly radio-tolerant and strongly concentrates radionuclides, as well as large amounts of toxic metals. This study helps in the understanding of the mechanisms involved in the accumulation and detoxification of silver and cobalt. Elemental distribution inside Coccomyxa actinabiotis cells was determined using synchrotron nano X-ray fluorescence spectroscopy at the ID22 nano fluorescence imaging beamline of the European Synchrotron Radiation Facility. The high resolution and high sensitivity of this technique enabled the assessment of elemental associations and exclusions in subcellular micro-algae compartments. A quantitative treatment of the scans was implemented to yield absolute concentrations of each endogenous and exogenous element with a spatial resolution of 100 nm and compared to the macroscopic content in cobalt and silver determined using inductively coupled plasma-mass spectrometry. The nano X-ray fluorescence imaging was complemented by transmission electron microscopy coupled to X-ray microanalysis (TEM-EDS), yielding differential silver distribution in the cell wall, cytosol, nucleus, chloroplast and mitochondria with unique resolution. The analysis of endogenous elements in control cells revealed that iron had a unique distribution; zinc, potassium, manganese, molybdenum, and phosphate had their maxima co-localized in the same area; and sulfur, copper and chlorine were almost homogeneously distributed among the whole cell. The subcellular distribution and quantification of cobalt and silver in micro-alga, assessed after controlled exposure to various concentrations, revealed that exogenous metals were mainly sequestered inside the cell rather than on mucilage or the cell wall, with preferential compartmentalization. Cobalt was homogeneously distributed outside of the chloroplast. Silver was localized in the cytosol at low concentration and in the whole cell excluding the nucleus at high concentration. Exposure to low concentrations of cobalt or silver did not alter the localization nor the concentration of endogenous elements within the cells. To our knowledge, this is the first report on element co-localization and segregation at the sub-cellular level in micro-algae by means of synchrotron nano X-ray fluorescence spectroscopy.

Tomato Ribonuclease LX with the Functional Endoplasmic Reticulum Retention Motif HDEF Is Expressed during Programmed Cell Death Processes, Including Xylem Differentiation, Germination, and Senescence1

PubMed Central

Lehmann, Karin; Hause, Bettina; Altmann, Dorit; Köck, Margret

2001-01-01

We have studied the subcellular localization of the acid S-like ribonuclease (RNase) LX in tomato (Lycopersicon esculentum Mill.) cells using a combination of biochemical and immunological methods. It was found that the enzyme, unexpectedly excluded from highly purified vacuoles, accumulates in the endoplasmic reticulum. The evidence that RNase LX is a resident of the endoplasmic reticulum (ER) is supported by an independent approach showing that the C-terminal peptide HDEF of RNase LX acts as an alternative ER retention signal in plants. For functional testing, the cellular distribution of chimeric protein constructs based on a marker protein, Brazil nut (Bertholletia excelsa) 2S albumin, was analyzed immunochemically in transgenic tobacco (Nicotiana tabacum) plants. Here, we report that the peptide motif is necessary and sufficient to accumulate 2S albumin constructs of both vacuolar and extracellular final destinations in the ER. We have shown immunochemically that RNase LX is specifically expressed during endosperm mobilization and leaf and flower senescence. Using immunofluorescence, RNase LX protein was detected in immature tracheary elements, suggesting a function in xylem differentiation. These results support a physiological function of RNase LX in selective cell death processes that are also thought to involve programmed cell death. It is assumed that RNase LX accumulates in an ER-derived compartment and is released by membrane disruption into the cytoplasma of those cells that are intended to undergo autolysis. These processes are accompanied by degradation of cellular components supporting a metabolic recycling function of the intracellular RNase LX. PMID:11598219

Chitin-induced and CHITIN ELICITOR RECEPTOR KINASE1 (CERK1) phosphorylation-dependent endocytosis of Arabidopsis thaliana LYSIN MOTIF-CONTAINING RECEPTOR-LIKE KINASE5 (LYK5).

PubMed

Erwig, Jan; Ghareeb, Hassan; Kopischke, Michaela; Hacke, Ronja; Matei, Alexandra; Petutschnig, Elena; Lipka, Volker

2017-07-01

To detect potential pathogens, plants perceive the fungal polysaccharide chitin through receptor complexes containing lysin motif receptor-like kinases (LysM-RLKs). To investigate the ligand-induced spatial dynamics of chitin receptor components, we studied the subcellular behaviour of two Arabidopsis thaliana LysM-RLKs involved in chitin signalling, CHITIN ELICITOR RECEPTOR KINASE1 (CERK1) and LYSIN MOTIF-CONTAINING RECEPTOR-LIKE KINASE5. We performed standard and quantitative confocal laser scanning microscopy on stably transformed A. thaliana plants expressing fluorescently tagged CERK1 and LYK5 from their native promoters. Microscopy approaches were complemented by biochemical analyses in plants and in vitro. Both CERK1 and LYK5 localized to the plasma membrane and showed constitutive endomembrane trafficking. After chitin treatment, however, CERK1 remained at the plasma membrane while LYK5 relocalized into mobile intracellular vesicles. Detailed analyses revealed that chitin perception transiently induced the internalization of LYK5 into late endocytic compartments. Plants that lacked CERK1 or expressed an enzymatically inactive CERK1 variant did not exhibit chitin-induced endocytosis of LYK5. CERK1 could phosphorylate LYK5 in vitro and chitin treatment induced CERK1-dependent phosphorylation of LYK5 in planta. Our results suggest that chitin-induced phosphorylation by CERK1 triggers LYK5 internalization. Thus, our work identifies phosphorylation as a key regulatory step in endocytosis of plant RLKs and also provides evidence for receptor complex dissociation after ligand perception. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Membrane Compartmentalization Reducing the Mobility of Lipids and Proteins within a Model Plasma Membrane.

PubMed

Koldsø, Heidi; Reddy, Tyler; Fowler, Philip W; Duncan, Anna L; Sansom, Mark S P

2016-09-01

The cytoskeleton underlying cell membranes may influence the dynamic organization of proteins and lipids within the bilayer by immobilizing certain transmembrane (TM) proteins and forming corrals within the membrane. Here, we present coarse-grained resolution simulations of a biologically realistic membrane model of asymmetrically organized lipids and TM proteins. We determine the effects of a model of cytoskeletal immobilization of selected membrane proteins using long time scale coarse-grained molecular dynamics simulations. By introducing compartments with varying degrees of restraints within the membrane models, we are able to reveal how compartmentalization caused by cytoskeletal immobilization leads to reduced and anomalous diffusional mobility of both proteins and lipids. This in turn results in a reduced rate of protein dimerization within the membrane and of hopping of membrane proteins between compartments. These simulations provide a molecular realization of hierarchical models often invoked to explain single-molecule imaging studies of membrane proteins.

Spinning-induced Rhabdomyolysis and the Risk of Compartment Syndrome and Acute Kidney Injury

PubMed Central

DeFilippis, Ersilia M.; Kleiman, David A.; Derman, Peter B.; DiFelice, Gregory S.; Eachempati, Soumitra R.

2014-01-01

Exercise-induced rhabdomyolysis related to military training, marathon running, and other forms of strenuous exercise has been reported. The incidence of acute kidney injury appears to be lower in exercise-induced cases. We present 2 cases of exercise-induced rhabdomyolysis following spinning classes, one of which was further complicated by acute compartment syndrome requiring bilateral fasciotomies of the anterior thigh and acute kidney injury. With vigorous hydration and urine pH monitoring, both patients exhibited good mobility, sensation, and renal function on discharge. PMID:24982706

Overland Mobility of the Forces in the Canadian Environment,

DTIC Science & Technology

1977-01-14

to refer to prior kowledge and this is typified by the I examples of data bank Input In Fig 1. The data ublch Is used may be broadly classifiled as...I tics, suspension as a mobility limiting factor. k. The Enzine Compartment - selection of engines, power require- Seats, load factors, fuel...consumption, specific bulk, specific weight, cooling requirements, parasitic power losses. cooling - system design, fan types and applications, air flow in 3

Cellular and Subcellular Immunohistochemical Localization and Quantification of Cadmium Ions in Wheat (Triticum aestivum).

PubMed

Gao, Wei; Nan, Tiegui; Tan, Guiyu; Zhao, Hongwei; Tan, Weiming; Meng, Fanyun; Li, Zhaohu; Li, Qing X; Wang, Baomin

2015-01-01

The distribution of metallic ions in plant tissues is associated with their toxicity and is important for understanding mechanisms of toxicity tolerance. A quantitative histochemical method can help advance knowledge of cellular and subcellular localization and distribution of heavy metals in plant tissues. An immunohistochemical (IHC) imaging method for cadmium ions (Cd2+) was developed for the first time for the wheat Triticum aestivum grown in Cd2+-fortified soils. Also, 1-(4-Isothiocyanobenzyl)-ethylenediamine-N,N,N,N-tetraacetic acid (ITCB-EDTA) was used to chelate the mobile Cd2+. The ITCB-EDTA/Cd2+ complex was fixed with proteins in situ via the isothiocyano group. A new Cd2+-EDTA specific monoclonal antibody, 4F3B6D9A1, was used to locate the Cd2+-EDTA protein complex. After staining, the fluorescence intensities of sections of Cd2+-positive roots were compared with those of Cd2+-negative roots under a laser confocal scanning microscope, and the location of colloidal gold particles was determined with a transmission electron microscope. The results enable quantification of the Cd2+ content in plant tissues and illustrate Cd2+ translocation and cellular and subcellular responses of T. aestivum to Cd2+ stress. Compared to the conventional metal-S coprecipitation histochemical method, this new IHC method is quantitative, more specific and has less background interference. The subcellular location of Cd2+ was also confirmed with energy-dispersive X-ray microanalysis. The IHC method is suitable for locating and quantifying Cd2+ in plant tissues and can be extended to other heavy metallic ions.

Multi-scale continuum modeling of biological processes: from molecular electro-diffusion to sub-cellular signaling transduction

NASA Astrophysics Data System (ADS)

Cheng, Y.; Kekenes-Huskey, P.; Hake, J. E.; Holst, M. J.; McCammon, J. A.; Michailova, A. P.

2012-01-01

This paper presents a brief review of multi-scale modeling at the molecular to cellular scale, with new results for heart muscle cells. A finite element-based simulation package (SMOL) was used to investigate the signaling transduction at molecular and sub-cellular scales (http://mccammon.ucsd.edu/smol/, http://FETK.org) by numerical solution of the time-dependent Smoluchowski equations and a reaction-diffusion system. At the molecular scale, SMOL has yielded experimentally validated estimates of the diffusion-limited association rates for the binding of acetylcholine to mouse acetylcholinesterase using crystallographic structural data. The predicted rate constants exhibit increasingly delayed steady-state times, with increasing ionic strength, and demonstrate the role of an enzyme's electrostatic potential in influencing ligand binding. At the sub-cellular scale, an extension of SMOL solves a nonlinear, reaction-diffusion system describing Ca2+ ligand buffering and diffusion in experimentally derived rodent ventricular myocyte geometries. Results reveal the important role of mobile and stationary Ca2+ buffers, including Ca2+ indicator dye. We found that alterations in Ca2+-binding and dissociation rates of troponin C (TnC) and total TnC concentration modulate sub-cellular Ca2+ signals. The model predicts that reduced off-rate in the whole troponin complex (TnC, TnI, TnT) versus reconstructed thin filaments (Tn, Tm, actin) alters cytosolic Ca2+ dynamics under control conditions or in disease-linked TnC mutations. The ultimate goal of these studies is to develop scalable methods and theories for the integration of molecular-scale information into simulations of cellular-scale systems.

Phosphorylation of FMRP and alterations of FMRP complex underlie enhanced mLTD in adult rats triggered by early life seizures.

PubMed

Bernard, Paul B; Castano, Anna M; O'Leary, Heather; Simpson, Kameron; Browning, Michael D; Benke, Tim A

2013-11-01

Outside of Fragile X syndrome (FXS), the role of Fragile-X Mental Retardation Protein (FMRP) in mediating neuropsychological abnormalities is not clear. FMRP, p70-S6 kinase (S6K) and protein phosphatase 2A (PP2A) are thought to cooperate as a dynamic signaling complex. In our prior work, adult rats have enhanced CA1 hippocampal long-term depression (LTD) following an early life seizure (ELS). We now show that mGluR-mediated LTD (mLTD) is specifically enhanced following ELS, similar to FMRP knock-outs. Total FMRP expression is unchanged but S6K is hyperphosphorylated, consistent with S6K overactivation. We postulated that either disruption of the FMRP-S6K-PP2A complex and/or removal of this complex from synapses could explain our findings. Using subcellular fractionation, we were surprised to find that concentrations of FMRP and PP2A were undisturbed in the synaptosomal compartment but reduced in parallel in the cytosolic compartment. Following ELS FMRP phosphorylation was reduced in the cytosolic compartment and increased in the synaptic compartment, in parallel with the compartmentalization of S6K activation. Furthermore, FMRP and PP2A remain bound following ELS. In contrast, the interaction of S6K with FMRP is reduced by ELS. Blockade of PP2A results in enhanced mLTD; this is occluded by ELS. This suggests a critical role for the location and function of the FMRP-S6K-PP2A signaling complex in limiting the amount of mLTD. Specifically, non-synaptic targeting and the function of the complex may influence the "set-point" for regulating mLTD. Consistent with this, striatal-enriched protein tyrosine phosphatase (STEP), an FMRP "target" which regulates mLTD expression, is specifically increased in the synaptosomal compartment following ELS. Further, we provide behavioral data to suggest that FMRP complex dysfunction may underlie altered socialization, a symptom associated and observed in other rodent models of autism, including FXS. © 2013.

Dynein-Dependent Transport of the Hantaan Virus Nucleocapsid Protein to the Endoplasmic Reticulum-Golgi Intermediate Compartment▿

PubMed Central

Ramanathan, Harish N.; Chung, Dong-Hoon; Plane, Steven J.; Sztul, Elizabeth; Chu, Yong-kyu; Guttieri, Mary C.; McDowell, Michael; Ali, Georgia; Jonsson, Colleen B.

2007-01-01

In contrast to most negative-stranded RNA viruses, hantaviruses and other viruses in the family Bunyaviridae mature intracellularly, deriving the virion envelope from the endoplasmic reticulum (ER) or Golgi compartment. While it is generally accepted that Old World hantaviruses assemble and bud into the Golgi compartment, some studies with New World hantaviruses have raised the possibility of maturation at the plasma membrane as well. Overall, the steps leading to virion assembly remain largely undetermined for hantaviruses. Because hantaviruses do not have matrix proteins, the nucleocapsid protein (N) has been proposed to play a key role in assembly. Herein, we examine the intracellular trafficking and morphogenesis of the prototype Old World hantavirus, Hantaan virus (HTNV). Using confocal microscopy, we show that N colocalized with the ER-Golgi intermediate compartment (ERGIC) in HTNV-infected Vero E6 cells, not with the ER, Golgi compartment, or early endosomes. Brefeldin A, which effectively disperses the ER, the ERGIC, and Golgi membranes, redistributed N with the ERGIC, implicating membrane association; however, subcellular fractionation experiments showed the majority of N in particulate fractions. Confocal microscopy revealed that N was juxtaposed to and distributed along microtubules and, over time, became surrounded by vimentin cages. To probe cytoskeletal association further, we probed trafficking of N in cells treated with nocodazole and cytochalasin D, which depolymerize microtubules and actin, respectively. We show that nocodazole, but not cytochalasin D, affected the distribution of N and reduced levels of intracellular viral RNA. These results suggested the involvement of microtubules in trafficking of N, whose movement could occur via molecular motors such as dynein. Overexpression of dynamitin, which is associated with dynein-mediated transport, creates a dominant-negative phenotype blocking transport on microtubules. Overexpression of dynamitin reduced N accumulation in the perinuclear region, which further supports microtubule components in N trafficking. The combined results of these experiments support targeting of N to the ERGIC prior to its movement to the Golgi compartment and the requirement of an intact ERGIC for viral replication and, thus, the possibility of virus factories in this region. PMID:17537852

Isolating specific cell and tissue compartments from 3D images for quantitative regional distribution analysis using novel computer algorithms.

PubMed

Fenrich, Keith K; Zhao, Ethan Y; Wei, Yuan; Garg, Anirudh; Rose, P Ken

2014-04-15

Isolating specific cellular and tissue compartments from 3D image stacks for quantitative distribution analysis is crucial for understanding cellular and tissue physiology under normal and pathological conditions. Current approaches are limited because they are designed to map the distributions of synapses onto the dendrites of stained neurons and/or require specific proprietary software packages for their implementation. To overcome these obstacles, we developed algorithms to Grow and Shrink Volumes of Interest (GSVI) to isolate specific cellular and tissue compartments from 3D image stacks for quantitative analysis and incorporated these algorithms into a user-friendly computer program that is open source and downloadable at no cost. The GSVI algorithm was used to isolate perivascular regions in the cortex of live animals and cell membrane regions of stained spinal motoneurons in histological sections. We tracked the real-time, intravital biodistribution of injected fluorophores with sub-cellular resolution from the vascular lumen to the perivascular and parenchymal space following a vascular microlesion, and mapped the precise distributions of membrane-associated KCC2 and gephyrin immunolabeling in dendritic and somatic regions of spinal motoneurons. Compared to existing approaches, the GSVI approach is specifically designed for isolating perivascular regions and membrane-associated regions for quantitative analysis, is user-friendly, and free. The GSVI algorithm is useful to quantify regional differences of stained biomarkers (e.g., cell membrane-associated channels) in relation to cell functions, and the effects of therapeutic strategies on the redistributions of biomolecules, drugs, and cells in diseased or injured tissues. Copyright © 2014 Elsevier B.V. All rights reserved.

Dendritic spine dysgenesis in Autism Related Disorders

PubMed Central

Phillips, Mary; Pozzo-Miller, Lucas

2015-01-01

The activity-dependent structural and functional plasticity of dendritic spines has led to the long-standing belief that these neuronal compartments are the subcellular sites of learning and memory. Of relevance to human health, central neurons in several neuropsychiatric illnesses, including autism related disorders, have atypical numbers and morphologies of dendritic spines. These so-called dendritic spine dysgeneses found in individuals with autism related disorders are consistently replicated in experimental mouse models. Dendritic spine dysgenesis reflects the underlying synaptopathology that drives clinically relevant behavioral deficits in experimental mouse models, providing a platform for testing new therapeutic approaches. By examining molecular signaling pathways, synaptic deficits, and spine dysgenesis in experimental mouse models of autism related disorders we find strong evidence for mTOR to be a critical point of convergence and promising therapeutic target. PMID:25578949

Characterization of Si p-i-n diode for scanning transmission ion microanalysis of biological samples

NASA Astrophysics Data System (ADS)

Devès, G.; Matsuyama, S.; Barbotteau, Y.; Ishii, K.; Ortega, R.

2006-05-01

The performance of a silicon p-i-n diode (Hamamatsu S1223-01) for the detection of charged particles was investigated and compared with the response of a standard passivated implanted planar silicon (PIPS) detector. The photodiode was characterized by ion beam induced charge collection with a micrometer spatial resolution using proton and alpha particle beams in the 1-3MeV energy range. Results indicate that homogeneity, energy resolution, and reproducibility of detection of charged particles enable the use of the low cost silicon p-i-n device as a replacement of conventional PIPS detector during scanning transmission ion microanalysis experiments. The Si p-i-n diode detection setup was successfully applied to scanning transmission ion microscopy determination of subcellular compartments on human cancer cultured cells.

Role of Polyamines in Parasite Cell Architecture and Function.

PubMed

Vannier-Santos, Marcos A; Suarez-Fontes, Ana M

2017-01-01

In the absence of accessible, effective vaccines, the fight against parasitic disease relies mostly on chemotherapy. Nevertheless, the considerable side effects, high costs and growing number of refractory cases comprise substantial drawbacks. Thus, the search for new antiparasitic compounds remains a high priority. The polyamine biosynthesis, conversion and transport pathways offer different targets for selective chemotherapy. Polyamine analogues and other antagonists may provide tools in the search for new lead compounds. Light and electron microscopy techniques may encompass valuable approaches to elucidate the possible mechanisms of action of different antiparasitic compounds, allowing the identification of subcellular target compartments, presumably establishing the basis for a more rational drug design and/or planning of therapeutic strategies. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Prediction of intracellular exposure bridges the gap between target- and cell-based drug discovery

PubMed Central

Gordon, Laurie J.; Wayne, Gareth J.; Almqvist, Helena; Axelsson, Hanna; Seashore-Ludlow, Brinton; Treyer, Andrea; Lundbäck, Thomas; West, Andy; Hann, Michael M.; Artursson, Per

2017-01-01

Inadequate target exposure is a major cause of high attrition in drug discovery. Here, we show that a label-free method for quantifying the intracellular bioavailability (Fic) of drug molecules predicts drug access to intracellular targets and hence, pharmacological effect. We determined Fic in multiple cellular assays and cell types representing different targets from a number of therapeutic areas, including cancer, inflammation, and dementia. Both cytosolic targets and targets localized in subcellular compartments were investigated. Fic gives insights on membrane-permeable compounds in terms of cellular potency and intracellular target engagement, compared with biochemical potency measurements alone. Knowledge of the amount of drug that is locally available to bind intracellular targets provides a powerful tool for compound selection in early drug discovery. PMID:28701380

The G protein alpha subunit (GP alpha1) is associated with the ER and the plasma membrane in meristematic cells of Arabidopsis and cauliflower.

PubMed

Weiss, C A; White, E; Huang, H; Ma, H

1997-05-05

Towards the elucidation of the cellular function(s) of GP alpha1, we have characterized its subcellular localization using immunofluorescence and cell fractionation. GP alpha1 is not present in nuclei or chloroplasts. It is a membrane-bound protein, and analysis of isolated endoplasmic and plasma membranes indicates a good correlation between GP alpha1 in both the plasma membrane and the ER compartment. Interestingly, these results may suggest more different functions for GP alpha1: it might be involved in transmission of extracellular signals across the plasma membrane and in the cytoplasm, and/or it may also be involved in regulating some aspects of the ER functions or membrane trafficking between both membranes.

Frex and FrexH: Indicators of metabolic states in living cells.

PubMed

Zhao, Yuzheng; Yang, Yi

2012-01-01

Reduced nicotinamide adenine dinucleotide (NADH) and its oxidized form play central roles in energy and redox metabolisms. For many years, researchers have relied on the weak NADH endogenous fluorescence signal to determine the NADH level in living cells. We recently reported a series of genetically encoded fluorescent sensors highly specific for NADH. These sensors allow real-time, quantitative measurement of this significant molecule in different subcellular compartments. In this study, we provide a more detailed discussion of the benefits and limitations of these genetically encoded fluorescent sensors. These sensors are utilized in most laboratories without the need for sophisticated instruments because of their superior sensitivity and specificity. They are also viable alternatives to existing techniques for measuring the endogenous fluorescence of intracellular NAD(P)H.

Nanowire-based single-cell endoscopy

NASA Astrophysics Data System (ADS)

Yan, Ruoxue; Park, Ji-Ho; Choi, Yeonho; Heo, Chul-Joon; Yang, Seung-Man; Lee, Luke P.; Yang, Peidong

2012-03-01

One-dimensional smart probes based on nanowires and nanotubes that can safely penetrate the plasma membrane and enter biological cells are potentially useful in high-resolution and high-throughput gene and drug delivery, biosensing and single-cell electrophysiology. However, using such probes for optical communication across the cellular membrane at the subwavelength level remains limited. Here, we show that a nanowire waveguide attached to the tapered tip of an optical fibre can guide visible light into intracellular compartments of a living mammalian cell, and can also detect optical signals from subcellular regions with high spatial resolution. Furthermore, we show that through light-activated mechanisms the endoscope can deliver payloads into cells with spatial and temporal specificity. Moreover, insertion of the endoscope into cells and illumination of the guided laser did not induce any significant toxicity in the cells.

Multiple-labelling immunoEM using different sizes of colloidal gold: alternative approaches to test for differential distribution and colocalization in subcellular structures.

PubMed

Mayhew, Terry M; Lucocq, John M

2011-03-01

Various methods for quantifying cellular immunogold labelling on transmission electron microscope thin sections are currently available. All rely on sound random sampling principles and are applicable to single immunolabelling across compartments within a given cell type or between different experimental groups of cells. Although methods are also available to test for colocalization in double/triple immunogold labelling studies, so far, these have relied on making multiple measurements of gold particle densities in defined areas or of inter-particle nearest neighbour distances. Here, we present alternative two-step approaches to codistribution and colocalization assessment that merely require raw counts of gold particles in distinct cellular compartments. For assessing codistribution over aggregate compartments, initial statistical evaluation involves combining contingency table and chi-squared analyses to provide predicted gold particle distributions. The observed and predicted distributions allow testing of the appropriate null hypothesis, namely, that there is no difference in the distribution patterns of proteins labelled by different sizes of gold particle. In short, the null hypothesis is that of colocalization. The approach for assessing colabelling recognises that, on thin sections, a compartment is made up of a set of sectional images (profiles) of cognate structures. The approach involves identifying two groups of compartmental profiles that are unlabelled and labelled for one gold marker size. The proportions in each group that are also labelled for the second gold marker size are then compared. Statistical analysis now uses a 2 × 2 contingency table combined with the Fisher exact probability test. Having identified double labelling, the profiles can be analysed further in order to identify characteristic features that might account for the double labelling. In each case, the approach is illustrated using synthetic and/or experimental datasets and can be refined to correct observed labelling patterns to specific labelling patterns. These simple and efficient approaches should be of more immediate utility to those interested in codistribution and colocalization in multiple immunogold labelling investigations.

Design of mobile shelters for communication purposes

NASA Astrophysics Data System (ADS)

Lotens, W. A.; Leebeek, H. J.

1982-03-01

A general design for a future generation of shelters, to be used as mobile work places, is presented. Design criteria involve ergonomics, functional suitability, and air conditioning. Electronics, power supply, and personnel get their own compartments. Work space is provided for two people with room for two more. Center of mass and cable connections are considered. Air conditioning requirements are calculated with a computer program. The result is an integrated design, applicable to shelters for several purposes.

Traffic of chitin synthase 1 (CHS-1) to the Spitzenkörper and developing septa in hyphae of Neurospora crassa: actin dependence and evidence of distinct microvesicle populations.

PubMed

Sánchez-León, Eddy; Verdín, Jorge; Freitag, Michael; Roberson, Robert W; Bartnicki-Garcia, Salomon; Riquelme, Meritxell

2011-05-01

We describe the subcellular location of chitin synthase 1 (CHS-1), one of seven chitin synthases in Neurospora crassa. Laser scanning confocal microscopy of growing hyphae showed CHS-1-green fluorescent protein (GFP) localized conspicuously in regions of active wall synthesis, namely, the core of the Spitzenkörper (Spk), the apical cell surface, and developing septa. It was also present in numerous fine particles throughout the cytoplasm plus some large vacuoles in distal hyphal regions. Although the same general subcellular distribution was observed previously for CHS-3 and CHS-6, they did not fully colocalize. Dual labeling showed that the three different chitin synthases were contained in different vesicular compartments, suggesting the existence of a different subpopulation of chitosomes for each CHS. CHS-1-GFP persisted in the Spk during hyphal elongation but disappeared from the septum after its development was completed. Wide-field fluorescence microscopy and total internal reflection fluorescence microscopy revealed subapical clouds of particles, suggestive of chitosomes moving continuously toward the Spk. Benomyl had no effect on CHS-1-GFP localization, indicating that microtubules are not strictly required for CHS trafficking to the hyphal apex. Conversely, actin inhibitors caused severe mislocalization of CHS-1-GFP, indicating that actin plays a major role in the orderly traffic and localization of CHS-1 at the apex.

Extrasynaptic N-Methyl-d-aspartate (NMDA) Receptor Stimulation Induces Cytoplasmic Translocation of the CDKL5 Kinase and Its Proteasomal Degradation*

PubMed Central

Rusconi, Laura; Kilstrup-Nielsen, Charlotte; Landsberger, Nicoletta

2011-01-01

Mutations in the X-linked gene cyclin-dependent kinase-like 5 (CDKL5) have been found in patients with epileptic encephalopathy characterized by early onset intractable epilepsy, including infantile spasms and other types of seizures, severe developmental delay, and often the development of Rett syndrome-like features. Despite its clear involvement in proper brain development, CDKL5 functions are still far from being understood. In this study, we analyzed the subcellular localization of the endogenous kinase in primary murine hippocampal neurons. CDKL5 was localized both in nucleus and cytoplasm and, conversely to proliferating cells, did not undergo constitutive shuttling between these compartments. Nevertheless, glutamate stimulation was able to induce the exit of the kinase from the nucleus and its subsequent accumulation in the perinuclear cytoplasm. Moreover, we found that sustained glutamate stimulation promoted CDKL5 proteasomal degradation. Both events were mediated by the specific activation of extrasynaptic pool of N-methyl-d-aspartate receptors. Proteasomal degradation was also induced by withdrawal of neurotrophic factors and hydrogen peroxide treatment, two different paradigms of cell death. Altogether, our results indicate that both subcellular localization and expression of CDKL5 are modulated by the activation of extrasynaptic N-methyl-d-aspartate receptors and suggest regulation of CDKL5 by cell death pathways. PMID:21832092

Expression and subcellular localization of a novel nuclear acetylcholinesterase protein.

PubMed

Santos, Susana Constantino Rosa; Vala, Inês; Miguel, Cláudia; Barata, João T; Garção, Pedro; Agostinho, Paula; Mendes, Marta; Coelho, Ana V; Calado, Angelo; Oliveira, Catarina R; e Silva, João Martins; Saldanha, Carlota

2007-08-31

Acetylcholine is found in the nervous system and also in other cell types (endothelium, lymphocytes, and epithelial and blood cells), which are globally termed the non-neuronal cholinergic system. In this study we investigated the expression and subcellular localization of acetylcholinesterase (AChE) in endothelial cells. Our results show the expression of the 70-kDa AChE in both cytoplasmic and nuclear compartments. We also describe, for the first time, a nuclear and cytoskeleton-bound AChE isoform with approximately 55 kDa detected in endothelial cells. This novel isoform is decreased in response to vascular endothelial growth factor via the proteosomes pathway, and it is down-regulated in human leukemic T-cells as compared with normal T-cells, suggesting that the decreased expression of the 55-kDa AChE protein may contribute to an angiogenic response and associate with tumorigenesis. Importantly, we show that its nuclear expression is not endothelial cell-specific but also evidenced in non-neuronal and neuronal cells. Concerning neuronal cells, we can distinguish an exclusively nuclear expression in postnatal neurons in contrast to a cytoplasmic and nuclear expression in embryonic neurons, suggesting that the cell compartmentalization of this new AChE isoform is changed during the development of nervous system. Overall, our studies suggest that the 55-kDa AChE may be involved in different biological processes such as neural development, tumor progression, and angiogenesis.

Rab11-FIP3 Regulation of Lck Endosomal Traffic Controls TCR Signal Transduction.

PubMed

Bouchet, Jérôme; Del Río-Iñiguez, Iratxe; Vázquez-Chávez, Elena; Lasserre, Rémi; Agüera-González, Sonia; Cuche, Céline; McCaffrey, Mary W; Di Bartolo, Vincenzo; Alcover, Andrés

2017-04-01

The role of endosomes in receptor signal transduction is a long-standing question, which remains largely unanswered. The T cell Ag receptor and various components of its proximal signaling machinery are associated with distinct endosomal compartments, but how endosomal traffic affects T cell signaling remains ill-defined. In this article, we demonstrate in human T cells that the subcellular localization and function of the protein tyrosine kinase Lck depends on the Rab11 effector FIP3 (Rab11 family interacting protein-3). FIP3 overexpression or silencing and its ability to interact with Rab11 modify Lck subcellular localization and its delivery to the immunological synapse. Importantly, FIP3-dependent Lck localization controls early TCR signaling events, such as tyrosine phosphorylation of TCRζ, ZAP70, and LAT and intracellular calcium concentration, as well as IL-2 gene expression. Interestingly, FIP3 controls both steady-state and poststimulation phosphotyrosine and calcium levels. Finally, our findings indicate that FIP3 modulates TCR-CD3 cell surface expression via the regulation of steady-state Lck-mediated TCRζ phosphorylation, which in turn controls TCRζ protein levels. This may influence long-term T cell activation in response to TCR-CD3 stimulation. Therefore, our data underscore the importance of finely regulated endosomal traffic in TCR signal transduction and T cell activation leading to IL-2 production. Copyright © 2017 by The American Association of Immunologists, Inc.

Molecular cloning, subcellular localization and characterization of two adenylate kinases from cassava, Manihot esculenta Crantz cv. KU50.

PubMed

Boonrueng, Channarong; Tangpranomkorn, Surachat; Yazhisai, Uthaman; Sirikantaramas, Supaart

2016-10-01

Adenylate kinase (ADK) is a phosphotransferase that plays an important role in cellular energy homeostasis. Many isozymes located in different subcellular compartments have been reported. In this study, we focus on the characterization of cassava (Manihot esculenta) ADKs. We found 15 ADKs that are publicly available in the African cassava genome database. We cloned two ADKs, namely MeADK1 and MeADK2, which are phylogenetically grouped together with the plastidial ADK in potato. Both MeADK1 and MeADK2 showed 66% identity in the amino acid sequences with plastidial ADK in potato. However, we demonstrated that they are localized to mitochondria using GFP fusions of MeADK1 and MeADK2. The Escherichia coli-produced recombinant MeADK1 and MeADK2 preferred forward reactions that produce ATP. They exhibited similar specific activities. The semi-quantitative RT-PCR analysis showed that MeADK1 and MeADK2 in 2-month-old leaves have similar expression patterns under a diurnal light-dark cycle. However, MeADK2 transcripts were expressed at much higher levels than MeADK1 in 5-month-old leaves and roots. Thus, we conclude that MeADK2 might play a vital role in energy homeostasis in cassava mitochondria. Copyright © 2016 Elsevier GmbH. All rights reserved.

A toolset of aequorin expression vectors for in planta studies of subcellular calcium concentrations in Arabidopsis thaliana

PubMed Central

Mehlmer, Norbert; Parvin, Nargis; Hurst, Charlotte H.; Knight, Marc R.; Teige, Markus; Vothknecht, Ute C.

2014-01-01

Calcium has long been acknowledged as one of the most important signalling components in plants. Many abiotic and biotic stimuli are transduced into a cellular response by temporal and spatial changes in cellular calcium concentration and the calcium-sensitive protein aequorin has been exploited as a genetically encoded calcium indicator for the measurement of calcium in planta. The objective of this work was to generate a compatible set of aequorin expression plasmids for the generation of transgenic plant lines to measure changes in calcium levels in different cellular subcompartments. Aequorin was fused to different targeting peptides or organellar proteins as a means to localize it to the cytosol, the nucleus, the plasma membrane, and the mitochondria. Furthermore, constructs were designed to localize aequorin in the stroma as well as the inner and outer surface of the chloroplast envelope membranes. The modular set-up of the plasmids also allows the easy replacement of targeting sequences to include other compartments. An additional YFP-fusion was included to verify the correct subcellular localization of all constructs by laser scanning confocal microscopy. For each construct, pBin19-based binary expression vectors driven by the 35S or UBI10 promoter were made for Agrobacterium-mediated transformation. Stable Arabidopsis lines were generated and initial tests of several lines confirmed their feasibility to measure calcium signals in vivo. PMID:22213817

Melatonin biosynthesis in plants: multiple pathways catalyze tryptophan to melatonin in the cytoplasm or chloroplasts.

PubMed

Back, Kyoungwhan; Tan, Dun-Xian; Reiter, Russel J

2016-11-01

Melatonin is an animal hormone as well as a signaling molecule in plants. It was first identified in plants in 1995, and almost all enzymes responsible for melatonin biosynthesis had already been characterized in these species. Melatonin biosynthesis from tryptophan requires four-step reactions. However, six genes, that is, TDC, TPH, T5H, SNAT, ASMT, and COMT, have been implicated in the synthesis of melatonin in plants, suggesting the presence of multiple pathways. Two major pathways have been proposed based on the enzyme kinetics: One is the tryptophan/tryptamine/serotonin/N-acetylserotonin/melatonin pathway, which may occur under normal growth conditions; the other is the tryptophan/tryptamine/serotonin/5-methoxytryptamine/melatonin pathway, which may occur when plants produce large amounts of serotonin, for example, upon senescence. The melatonin biosynthetic capacity associated with conversion of tryptophan to serotonin is much higher than that associated with conversion of serotonin to melatonin, which yields a low level of melatonin synthesis in plants. Many melatonin intermediates are produced in various subcellular compartments, such as the cytoplasm, endoplasmic reticulum, and chloroplasts, which either facilitates or impedes the subsequent enzymatic steps. Depending on the pathways, the final subcellular sites of melatonin synthesis vary at either the cytoplasm or chloroplasts, which may differentially affect the mode of action of melatonin in plants. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Phosphatidic acid - a simple phospholipid with multiple faces.

PubMed

Zegarlińska, Jolanta; Piaścik, Magda; Sikorski, Aleksander F; Czogalla, Aleksander

2018-01-01

Phosphatidic acid (PA) is the simplest glycerophospholipid naturally occurring in living organisms, and even though its content among other cellular lipids is minor, it is drawing more and more attention due to its multiple biological functions. PA is a precursor for other phospholipids, acts as a lipid second messenger and, due to its structural properties, is also a modulator of membrane shape. Although much is known about interaction of PA with its effectors, the molecular mechanisms remain unresolved to a large degree. Throughout many of the well-characterized PA cellular sensors, no conserved binding domain can be recognized. Moreover, not much is known about the cellular dynamics of PA and how it is distributed among subcellular compartments. Remarkably, PA can play distinct roles within each of these compartments. For example, in the nucleus it behaves as a mitogen, influencing gene expression regulation, and in the Golgi membrane it plays a role in membrane trafficking. Here, we discuss how a biophysical experimental approach enabled PA behavior to be described in the context of a lipid bilayer and to what extent various physicochemical conditions may modulate the functional properties of this lipid. Understanding these aspects would help to unravel specific mechanisms of PA-driven membrane transformations and protein recruitment and thus would lead to a clearer picture of the biological role of PA.

Capturing novel mouse genes encoding chromosomal and other nuclear proteins.

PubMed

Tate, P; Lee, M; Tweedie, S; Skarnes, W C; Bickmore, W A

1998-09-01

The burgeoning wealth of gene sequences contrasts with our ignorance of gene function. One route to assigning function is by determining the sub-cellular location of proteins. We describe the identification of mouse genes encoding proteins that are confined to nuclear compartments by splicing endogeneous gene sequences to a promoterless betageo reporter, using a gene trap approach. Mouse ES (embryonic stem) cell lines were identified that express betageo fusions located within sub-nuclear compartments, including chromosomes, the nucleolus and foci containing splicing factors. The sequences of 11 trapped genes were ascertained, and characterisation of endogenous protein distribution in two cases confirmed the validity of the approach. Three novel proteins concentrated within distinct chromosomal domains were identified, one of which appears to be a serine/threonine kinase. The sequence of a gene whose product co-localises with splicesome components suggests that this protein may be an E3 ubiquitin-protein ligase. The majority of the other genes isolated represent novel genes. This approach is shown to be a powerful tool for identifying genes encoding novel proteins with specific sub-nuclear localisations and exposes our ignorance of the protein composition of the nucleus. Motifs in two of the isolated genes suggest new links between cellular regulatory mechanisms (ubiquitination and phosphorylation) and mRNA splicing and chromosome structure/function.

Cellular repressor of E1A-stimulated genes is a bona fide lysosomal protein which undergoes proteolytic maturation during its biosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaehs, Philipp; Weidinger, Petra; Probst, Olivia C.

2008-10-01

Cellular repressor of E1A-stimulated genes (CREG) has been reported to be a secretory glycoprotein implicated in cellular growth and differentiation. We now show that CREG is predominantly localized within intracellular compartments. Intracellular CREG was found to lack an N-terminal peptide present in the secreted form of the protein. In contrast to normal cells, CREG is largely secreted by fibroblasts missing both mannose 6-phosphate receptors. This is not observed in cells lacking only one of them. Mass spectrometric analysis of recombinant CREG revealed that the protein contains phosphorylated oligosaccharides at either of its two N-glycosylation sites. Cellular CREG was found tomore » cosediment with lysosomal markers upon subcellular fractionation by density-gradient centrifugation. In fibroblasts expressing a CREG-GFP fusion construct, the heterologous protein was detected in compartments containing lysosomal proteins. Immunolocalization of endogenous CREG confirmed that intracellular CREG is localized in lysosomes. Proteolytic processing of intracellular CREG involves the action of lysosomal cysteine proteinases. These results establish that CREG is a lysosomal protein that undergoes proteolytic maturation in the course of its biosynthesis, carries the mannose 6-phosphate recognition marker and depends on the interaction with mannose 6-phosphate receptors for efficient delivery to lysosomes.« less

Organelle redox autonomy during environmental stress.

PubMed

Bratt, Avishay; Rosenwasser, Shilo; Meyer, Andreas; Fluhr, Robert

2016-09-01

Oxidative stress is generated in plants because of inequalities in the rate of reactive oxygen species (ROS) generation and scavenging. The subcellular redox state under various stress conditions was assessed using the redox reporter roGFP2 targeted to chloroplastic, mitochondrial, peroxisomal and cytosolic compartments. In parallel, the vitality of the plant was measured by ion leakage. Our results revealed that during certain physiological stress conditions the changes in roGFP2 oxidation are comparable to application of high concentrations of exogenous H2 O2 . Under each stress, particular organelles were affected. Conditions of extended dark stress, or application of elicitor, impacted chiefly on the status of peroxisomal redox state. In contrast, conditions of drought or high light altered the status of mitochondrial or chloroplast redox state, respectively. Amalgamation of the results from diverse environmental stresses shows cases of organelle autonomy as well as multi-organelle oxidative change. Importantly, organelle-specific oxidation under several stresses proceeded cell death as measured by ion leakage, suggesting early roGFP oxidation as predictive of cell death. The measurement of redox state in multiple compartments enables one to look at redox state connectivity between organelles in relation to oxidative stress as well as assign a redox fingerprint to various types of stress conditions. © 2016 John Wiley & Sons Ltd.

Commensal-Associated Molecular Patterns Induce Selective Toll-Like Receptor-Trafficking from Apical Membrane to Cytoplasmic Compartments in Polarized Intestinal Epithelium

PubMed Central

Cario, Elke; Brown, Dennis; McKee, Mary; Lynch-Devaney, Kathryn; Gerken, Guido; Podolsky, Daniel K.

2002-01-01

Commensal-associated molecular patterns, the major products of nonpathogenic bacteria, are present at high concentrations at the apical surface of the intestinal epithelium. However, the nature of the interaction of commensal-associated molecular patterns with the lumenal surface of the epithelium has not been defined. We have recently demonstrated that intestinal epithelial cells constitutively express several Toll-like receptors (TLRs) in vitro and in vivo that seem to be the key receptors responsible for immune cell activation in response to various bacterial products. In this study we characterize the subcellular distribution of two major TLRs, TLR2 and TLR4, and their ligand-specific dynamic regulation in the model human intestinal epithelial cell line T84. Immunocytochemical studies indicate that TLR2 and TLR4 are constitutively expressed at the apical pole of differentiated T84 cells. After stimulation with lipopolysaccharide or peptidoglycan, TLRs selectively traffic to cytoplasmic compartments near the basolateral membrane. Thus, we demonstrate that TLRs are positioned at the apical pole where they are poised to monitor the sensitive balance of the lumenal microbial array. The results of this dynamic epithelial surveillance can then be conveyed to the underlying cell populations of the lamina propria via these innate immune pattern recognition receptors. PMID:11786410

Localization of azithromycin in Toxoplasma gondii-infected cells.

PubMed Central

Schwab, J C; Cao, Y; Slowik, M R; Joiner, K A

1994-01-01

Agents effective against intracellular pathogens must enter infected cells, crossing vacuolar membranes surrounding the organisms and then penetrating into the microbe and localizing to the microbial target site. We have characterized these parameters for azithromycin entry into Toxoplasma gondii-infected Chinese hamster ovary cells and murine macrophage-like J774 cells. Azithromycin uptake into infected host cells was concentrative and was dependent upon proton gradients. Subcellular fractionation of azithromycin-loaded infected CHO cells demonstrated > 95% intracellular drug in host cell lysosomes and cytosol, with < 5% associated with the parasite. Uptake of azithromycin into the T. gondii vacuole increased if parasites were coated with antibody prior to internalization by murine J774 cells, conditions which result in the formation of acidified phagolysosomes. No redistribution or retention of azithromycin in the parasite was observed when drug efflux from antibiotic-loaded infected CHO cells was monitored. Azithromycin entry into extracellular T. gondii was concentrative, was temperature and pH dependent, and was not different when azithromycin-sensitive and -resistant parasites were compared. These results demonstrate that azithromycin concentrates primarily in acidified compartments in parasites and host cells. The high concentration of azithromycin within these compartments may not be biologically relevant to inhibition of intracellular parasite growth by this agent. PMID:7979295

Lysosomal trafficking regulator Lyst links membrane trafficking to toll-like receptor–mediated inflammatory responses

PubMed Central

Krautkrämer, Martina

2017-01-01

Subcellular compartmentalization of receptor signaling is an emerging principle in innate immunity. However, the functional integration of receptor signaling pathways into membrane trafficking routes and its physiological relevance for immune responses is still largely unclear. In this study, using Lyst-mutant beige mice, we show that lysosomal trafficking regulator Lyst links endolysosomal organization to the selective control of toll-like receptor 3 (TLR3)– and TLR4-mediated proinflammatory responses. Consequently, Lyst-mutant mice showed increased susceptibility to bacterial infection and were largely resistant to endotoxin-induced septic shock. Mechanistic analysis revealed that Lyst specifically controls TLR3- and TLR4-induced endosomal TRIF (TIR domain–containing adapter-inducing interferon β) signaling pathways. Loss of functional Lyst leads to dysregulated phagosomal maturation, resulting in a failure to form an activation-induced Rab7+ endosomal/phagosomal compartment. This specific Rab7+ compartment was further demonstrated to serve as a major site for active TRIF signaling events, thus linking phagosomal maturation to specific TLR signaling pathways. The immunoregulatory role of Lyst on TLR signaling pathways was confirmed in human cells by CRISPR/Cas9-mediated gene inactivation. As mutations in LYST cause human Chédiak-Higashi syndrome, a severe immunodeficiency, our findings also contribute to a better understanding of human disease mechanisms. PMID:27881733

Monitoring the change of mitochondrial morphology and its metabolism of the breast cancer cells with the treatment of Hsp70 inhibitor during heat shock by fluorescence imaging

NASA Astrophysics Data System (ADS)

Yu, Biying; Yang, Hongqin; Zhang, Xiaoman; Li, Hui

2016-10-01

Heat shock (HS) is one of the best-studied exogenous cellular stresses, and all cellular compartments and metabolic processes are involved in HS response. The heat shock proteins (Hsps) expression enhanced during HS mainly localized in subcellular compartments, such as cytosol, endoplasmic reticulum and mitochandria. The major inducible heat shock protein 70 (Hsp70) modulate cellular homeostasis and promote cellular survival by blocking a caspase independent cell death through its association with apoptosis inducing factor. Mitochondria as the critical elements of HS response that participate in key metabolic reactions, and the changes in mitochonrial morphology may impact on mitochondrial metabolism. In this paper, the changes of mitorchondrial morphology in breast cancer cell have been monitored in real time after heat shock (43 °) by the fluorescence imaging, and the influence of Hsp70 inhibitor on mitochandrial structures have also been investigated. Then the information of mitochondrial metabolism which can be characterized by the level of the mitochondrial membrane potential has also been obtained wihout/with the treatment of Hsp70 inhibitor. Our data indicated that the mitochandrial morphology were related with the mitochandrial membrane potential, and the mitochandrial membrane potential was influenced significantly with the treatment of Hsp70 inhibitor during HS.

Iron repletion relocalizes hephaestin to a proximal basolateral compartment in polarized MDCK and Caco2 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Seung-Min; Department of Nutritional Science and Toxicology, University of California, Berkeley, CA; Attieh, Zouhair K.

2012-05-11

Highlights: Black-Right-Pointing-Pointer Hephaestin localizes in the perinuclear space in non-polarized cells. Black-Right-Pointing-Pointer Hephaestin localizes in the perinuclear space in iron deficient and polarized cells. Black-Right-Pointing-Pointer Hephaestin with apical iron moves near to basolateral membrane of polarized cells. Black-Right-Pointing-Pointer Peri-basolateral location of hephaestin is accessible to the extracellular space. Black-Right-Pointing-Pointer Hephaestin is involved in iron mobilization from the intestine to circulation. -- Abstract: While intestinal cellular iron entry in vertebrates employs multiple routes including heme and non-heme routes, iron egress from these cells is exclusively channeled through the only known transporter, ferroportin. Reduced intestinal iron export in sex-linked anemia mice implicatesmore » hephaestin, a ferroxidase, in this process. Polarized cells are exposed to two distinct environments. Enterocytes contact the gut lumen via the apical surface of the cell, and through the basolateral surface, to the body. Previous studies indicate both local and systemic control of iron uptake. We hypothesized that differences in iron availability at the apical and/or basolateral surface may modulate iron uptake via cellular localization of hephaestin. We therefore characterized the localization of hephaestin in two models of polarized epithelial cell lines, MDCK and Caco2, with varying iron availability at the apical and basolateral surfaces. Our results indicate that hephaestin is expressed in a supra-nuclear compartment in non-polarized cells regardless of the iron status of the cells and in iron deficient and polarized cells. In polarized cells, we found that both apical (as FeSO{sub 4}) and basolateral iron (as the ratio of apo-transferrin to holo-transferrin) affect mobilization of hephaestin from the supra-nuclear compartment. We find that the presence of apical iron is essential for relocalization of hephaestin to a cellular compartment in close proximity but not overlapping with the basolateral surface. Surface biotinylation studies indicate that hephaestin in the peri-basolateral location is accessible to the extra-cellular environment. These results support the hypothesis that hephaestin is involved in iron mobilization of iron from the intestine to circulation.« less

Skylab

NASA Image and Video Library

1972-01-01

This photograph, with callouts, depicts the experiment area of the forward compartment at the upper level of the Orbital Workshop. The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment.

Lead in bone: Implications for toxicology during pregnancy and lactation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silbergeld, E.K.

1991-02-01

Advances in understanding the distribution and retention of lead in mineralized tissues are important for two reasons: first, bone lead may be a more accurate dosimeter of integrated absorption associated with chronic exposures, and second, bone lead may be a source of internal exposure to the host organism. Little attention has been paid to this second aspect, the remobilization of lead from bone. Mobilization of lead from bone is likely to occur during periods of altered mineral metabolism; since calciotropic factors determine the uptake and storage of lead in this compartment, changes in calcium-related regulatory factors are likely to affectmore » lead compartmentation. Calcium metabolism changes drastically in humans during preganacy and lactation; although relatively little is known of lead kinetics during these critical periods, it is likely that bone lead is mobilized and transferred to the more bioavailable compartment of the maternal circulation, with potential toxic effects on the fetus and the mother.« less

Physiologic volume of phosphorus during hemodialysis: predictions from a pseudo one-compartment model.

PubMed

Leypoldt, John K; Akonur, Alp; Agar, Baris U; Culleton, Bruce F

2012-10-01

The kinetics of plasma phosphorus concentrations during hemodialysis (HD) are complex and cannot be described by conventional one- or two-compartment kinetic models. It has recently been shown by others that the physiologic (or apparent distribution) volume for phosphorus (Vr-P) increases with increasing treatment time and shows a large variation among patients treated by thrice weekly and daily HD. Here, we describe the dependence of Vr-P on treatment time and predialysis plasma phosphorus concentration as predicted by a novel pseudo one-compartment model. The kinetics of plasma phosphorus during conventional and six times per week daily HD were simulated as a function of treatment time per session for various dialyzer phosphate clearances and patient-specific phosphorus mobilization clearances (K(M)). Vr-P normalized to extracellular volume from these simulations were reported and compared with previously published empirical findings. Simulated results were relatively independent of dialyzer phosphate clearance and treatment frequency. In contrast, Vr-P was strongly dependent on treatment time per session; the increase in Vr-P with treatment time was larger for higher values of K(M). Vr-P was inversely dependent on predialysis plasma phosphorus concentration. There was significant variation among predicted Vr-P values, depending largely on the value of K(M). We conclude that a pseudo one-compartment model can describe the empirical dependence of the physiologic volume of phosphorus on treatment time and predialysis plasma phosphorus concentration. Further, the variation in physiologic volume of phosphorus among HD patients is largely due to differences in patient-specific phosphorus mobilization clearance. © 2012 The Authors. Hemodialysis International © 2012 International Society for Hemodialysis.

Absence of Peroxiredoxin 6 Amplifies the Effect of Oxidant Stress on Mobility and SCSA/CMA3 Defined Chromatin Quality and Impairs Fertilizing Ability of Mouse Spermatozoa1

PubMed Central

Ozkosem, Burak; Feinstein, Sheldon I.; Fisher, Aron B.; O'Flaherty, Cristian

2016-01-01

Oxidative stress, the imbalance between reactive oxygen species production and antioxidant defenses, is associated with male infertility. Peroxiredoxins (PRDXs) are antioxidant enzymes with a wide distribution in spermatozoa. PRDX6 is highly abundant and located in all subcellular compartments of the spermatozoon. Infertile men have lower levels of sperm PRDX6 associated with low sperm motility and high DNA damage. In order to better understand the role of PRDX6 in male reproduction, the aim of this study was to elucidate the impact of the lack of PRDX6 on male mouse fertility. Spermatozoa lacking PRDX6 showed significantly increased levels of cellular oxidative damage evidenced by high levels of lipid peroxidation, 8-hydroxy-deoxyguanosine (DNA oxidation), and protein oxidation (S-glutathionylation and carbonylation), lower sperm chromatin quality (high DNA fragmentation and low DNA compaction, due to low levels of protamination and a high percentage of free thiols), along with decreased sperm motility and impairment of capacitation as compared with wild-type (WT) spermatozoa. These manifestations of damage are exacerbated by tert-butyl hydroperoxide treatment in vivo. While WT males partially recovered the quality of their spermatozoa (in terms of motility and sperm DNA integrity), Prdx6−/− males showed higher levels of sperm damage (lower motility and chromatin integrity) 6 mo after the end of treatment. In conclusion, Prdx6−/− males are more vulnerable to oxidative stress than WT males, resulting in impairment of sperm quality and ability to fertilize the oocyte, compatible with the subfertility phenotype observed in these knockout mice. PMID:26792942

Absence of Peroxiredoxin 6 Amplifies the Effect of Oxidant Stress on Mobility and SCSA/CMA3 Defined Chromatin Quality and Impairs Fertilizing Ability of Mouse Spermatozoa.

PubMed

Ozkosem, Burak; Feinstein, Sheldon I; Fisher, Aron B; O'Flaherty, Cristian

2016-03-01

Oxidative stress, the imbalance between reactive oxygen species production and antioxidant defenses, is associated with male infertility. Peroxiredoxins (PRDXs) are antioxidant enzymes with a wide distribution in spermatozoa. PRDX6 is highly abundant and located in all subcellular compartments of the spermatozoon. Infertile men have lower levels of sperm PRDX6 associated with low sperm motility and high DNA damage. In order to better understand the role of PRDX6 in male reproduction, the aim of this study was to elucidate the impact of the lack of PRDX6 on male mouse fertility. Spermatozoa lacking PRDX6 showed significantly increased levels of cellular oxidative damage evidenced by high levels of lipid peroxidation, 8-hydroxy-deoxyguanosine (DNA oxidation), and protein oxidation (S-glutathionylation and carbonylation), lower sperm chromatin quality (high DNA fragmentation and low DNA compaction, due to low levels of protamination and a high percentage of free thiols), along with decreased sperm motility and impairment of capacitation as compared with wild-type (WT) spermatozoa. These manifestations of damage are exacerbated by tert-butyl hydroperoxide treatment in vivo. While WT males partially recovered the quality of their spermatozoa (in terms of motility and sperm DNA integrity), Prdx6(-/-) males showed higher levels of sperm damage (lower motility and chromatin integrity) 6 mo after the end of treatment. In conclusion, Prdx6(-/-) males are more vulnerable to oxidative stress than WT males, resulting in impairment of sperm quality and ability to fertilize the oocyte, compatible with the subfertility phenotype observed in these knockout mice. © 2016 by the Society for the Study of Reproduction, Inc.

Host cell remodeling by pathogens: the exomembrane system in Plasmodium-infected erythrocytes

PubMed Central

Sherling, Emma S.; van Ooij, Christiaan

2016-01-01

Malaria is caused by infection of erythrocytes by parasites of the genus Plasmodium. To survive inside erythrocytes, these parasites induce sweeping changes within the host cell, one of the most dramatic of which is the formation of multiple membranous compartments, collectively referred to as the exomembrane system. As an uninfected mammalian erythrocyte is devoid of internal membranes, the parasite must be the force and the source behind the formation of these compartments. Even though the first evidence of the presence these of internal compartments was obtained over a century ago, their functions remain mostly unclear, and in some cases completely unknown, and the mechanisms underlying their formation are still mysterious. In this review, we provide an overview of the different parts of the exomembrane system, describing the parasitophorous vacuole, the tubovesicular network, Maurer's clefts, the caveola-vesicle complex, J dots and other mobile compartments, and the small vesicles that have been observed in Plasmodium-infected cells. Finally, we combine the data into a simplified view of the exomembrane system and its relation to the alterations of the host erythrocyte. PMID:27587718

Skylab

NASA Image and Video Library

1972-01-01

This image, with callouts, depicts the storage area of the forward compartment at the upper level of the Orbital Workshop (OWS). The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment.

Predict subcellular locations of singleplex and multiplex proteins by semi-supervised learning and dimension-reducing general mode of Chou's PseAAC.

PubMed

Pacharawongsakda, Eakasit; Theeramunkong, Thanaruk

2013-12-01

Predicting protein subcellular location is one of major challenges in Bioinformatics area since such knowledge helps us understand protein functions and enables us to select the targeted proteins during drug discovery process. While many computational techniques have been proposed to improve predictive performance for protein subcellular location, they have several shortcomings. In this work, we propose a method to solve three main issues in such techniques; i) manipulation of multiplex proteins which may exist or move between multiple cellular compartments, ii) handling of high dimensionality in input and output spaces and iii) requirement of sufficient labeled data for model training. Towards these issues, this work presents a new computational method for predicting proteins which have either single or multiple locations. The proposed technique, namely iFLAST-CORE, incorporates the dimensionality reduction in the feature and label spaces with co-training paradigm for semi-supervised multi-label classification. For this purpose, the Singular Value Decomposition (SVD) is applied to transform the high-dimensional feature space and label space into the lower-dimensional spaces. After that, due to limitation of labeled data, the co-training regression makes use of unlabeled data by predicting the target values in the lower-dimensional spaces of unlabeled data. In the last step, the component of SVD is used to project labels in the lower-dimensional space back to those in the original space and an adaptive threshold is used to map a numeric value to a binary value for label determination. A set of experiments on viral proteins and gram-negative bacterial proteins evidence that our proposed method improve the classification performance in terms of various evaluation metrics such as Aiming (or Precision), Coverage (or Recall) and macro F-measure, compared to the traditional method that uses only labeled data.

Chelation in metal intoxication. VIII. Removal of chromium from organs of potassium chromate administered rats.

PubMed

Behari, J R; Tandon, S K

1980-03-01

Some polyaminocarboxylic acids were examined for their ability to mobilize chromium from certain vital organs, their subcellular fractions, and blood cells of potassium chromate administered rats. Hexamethylene 1,6-diamino tetraacetic acid (TDTA), triethylene tetramine hexaacetic acid (TTHA), and ethylene diamine di (O-hydroxylphenyl acetic acid) (EDDHA) may be useful in preventing or reducing chromate toxicity. No definite relationship could be observed between the structure of the chelating agents and their chromium-removing capacity.

A series of terpyridine containing flexible amino diethylacetate derivatives with large two-photon action cross-sections for effective mitochondrial imaging in living liver cancerous cells

NASA Astrophysics Data System (ADS)

Jia, Ran; Zhu, Yingying; Hu, Lei; Xiong, Qiru; Zhao, Meng; Zhang, Mingzhu; Tian, Xiaohe

2018-01-01

Small molecules possess large two-photon action cross sections (Φσ) are highly demanded for biological purpose. Herein, three novel terpyridine containing flexible amino diethylacetate organic small molecules (A1, A2 and A3) were rationally designed and their photophysical properties were investigated both experimentally and theoretically. The results revealed that the three chromophores possess large Φσ and remarkable Stokes' shift in high polar solvents, which are particularly benefit for further biological imaging application. One chromophore (A1) displayed an effective intracellular uptake against lung cancerous living cells A549. Colocalization studies suggested the internalized subcellular compartment was mitochondria. Consequently, chromophore A1 provides a promising platform to directly monitor mitochondria in living cells under two-photon confocal laser scanning microscopy.

Dendritic spine dysgenesis in autism related disorders.

PubMed

Phillips, Mary; Pozzo-Miller, Lucas

2015-08-05

The activity-dependent structural and functional plasticity of dendritic spines has led to the long-standing belief that these neuronal compartments are the subcellular sites of learning and memory. Of relevance to human health, central neurons in several neuropsychiatric illnesses, including autism related disorders, have atypical numbers and morphologies of dendritic spines. These so-called dendritic spine dysgeneses found in individuals with autism related disorders are consistently replicated in experimental mouse models. Dendritic spine dysgenesis reflects the underlying synaptopathology that drives clinically relevant behavioral deficits in experimental mouse models, providing a platform for testing new therapeutic approaches. By examining molecular signaling pathways, synaptic deficits, and spine dysgenesis in experimental mouse models of autism related disorders we find strong evidence for mTOR to be a critical point of convergence and promising therapeutic target. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Pseudoscaffolds and anchoring proteins: the difference is in the details

PubMed Central

Aggarwal-Howarth, Stacey; Scott, John D.

2017-01-01

Pseudokinases and pseudophosphatases possess the ability to bind substrates without catalyzing their modification, thereby providing a mechanism to recruit potential phosphotargets away from active enzymes. Since many of these pseudoenzymes possess other characteristics such as localization signals, separate catalytic sites, and protein–protein interaction domains, they have the capacity to influence signaling dynamics in local environments. In a similar manner, the targeting of signaling enzymes to subcellular locations by A-kinase-anchoring proteins (AKAPs) allows for precise and local control of second messenger signaling events. Here, we will discuss how pseudoenzymes form ‘pseudoscaffolds’ and compare and contrast this compartment-specific regulatory role with the signal organization properties of AKAPs. The mitochondria will be the focus of this review, as they are dynamic organelles that influence a broad range of cellular processes such as metabolism, ATP synthesis, and apoptosis. PMID:28408477

Transient complex peroxisomal interactions

PubMed Central

Bonekamp, Nina A.; Schrader, Michael

2012-01-01

Mitochondria and peroxisomes are ubiquitous subcellular organelles that fulfill essential metabolic functions, rendering them indispensable for human development and health. Both are highly dynamic organelles that can undergo remarkable changes in morphology and number to accomplish cellular needs. While mitochondrial dynamics are also regulated by frequent fusion events, the fusion of mature peroxisomes in mammalian cells remained a matter of debate. In our recent study, we clarified systematically that there is no complete fusion of mature peroxisomes analogous to mitochondria. Moreover, in contrast to key division components such as DLP1, Fis1 or Mff, mitochondrial fusion proteins were not localized to peroxisomes. However, we discovered and characterized novel transient, complex interactions between individual peroxisomes which may contribute to the homogenization of the often heterogeneous peroxisomal compartment, e.g., by distribution of metabolites, signals or other “molecular information” via interperoxisomal contact sites. PMID:23336019

Detection and Immunolabeling of Peroxisomal Proteins.

PubMed

Schrader, Tina A; Islinger, Markus; Schrader, Michael

2017-01-01

Peroxisomes are essential organelles in mammals which contribute to cellular lipid metabolism and redox homeostasis. The spectrum of their functions in human health and disease is far from being complete, and unexpected and novel roles of peroxisomes are being discovered. To date, those include novel biological roles in antiviral defence, as intracellular signaling platforms and as protective organelles in sensory cells. Furthermore, peroxisomes are part of a complex network of interacting subcellular compartments which involves metabolic cooperation, cross-talk and membrane contacts. As potentially novel peroxisomal proteins are continuously discovered, there is great interest in the verification of their peroxisomal localization. Here, we present protocols used successfully in our laboratory for the detection and immunolabeling of peroxisomal proteins in cultured mammalian cells. We present immunofluorescence and fluorescence-based techniques as well as reagents to determine peroxisome-specific targeting and localization of candidate proteins.

Preparation of Gap Junctions in Membrane Microdomains for Immunoprecipitation and Mass Spectrometry Interactome Analysis.

PubMed

Fowler, Stephanie; Akins, Mark; Bennett, Steffany A L

2016-01-01

Protein interaction networks at gap junction plaques are increasingly implicated in a variety of intracellular signaling cascades. Identifying protein interactions of integral membrane proteins is a valuable tool for determining channel function. However, several technical challenges exist. Subcellular fractionation of the bait protein matrix is usually required to identify less abundant proteins in complex homogenates. Sufficient solvation of the lipid environment without perturbation of the protein interactome must also be achieved. The present chapter describes the flotation of light and heavy liver tissue membrane microdomains to facilitate the identification and analysis of endogenous gap junction proteins and includes technical notes for translation to other integral membrane proteins, tissues, or cell culture models. These procedures are valuable tools for the enrichment of gap junction membrane compartments and for the identification of gap junction signaling interactomes.

Toward intracellular targeted delivery of cancer therapeutics: progress and clinical outlook for brain tumor therapy.

PubMed

Pandya, Hetal; Debinski, Waldemar

2012-08-01

A number of anti-cancer drugs have their targets localized to particular intracellular compartments. These drugs reach the targets mainly through diffusion, dependent on biophysical and biochemical forces that allow cell penetration. This means that both cancer cells and normal cells will be subjected to such diffusion; hence many of these drugs, like chemotherapeutics, are potentially toxic and the concentration achieved at the site of their action is often suboptimal. The same relates to radiation that indiscriminately affects normal and diseased cells. However, nature-designed systems enable compounds present in the extracellular environment to end up inside the cell and even travel to more specific intracellular compartments. For example, viruses and bacterial toxins can more or less specifically recognize eukaryotic cells, enter these cells, and direct some protein portions to designated intracellular areas. These phenomena have led to creative thinking, such as employing viruses or bacterial toxins for cargo delivery to cells and, more specifically, to cancer cells. Proteins can be genetically engineered in order to not only mimic what viruses and bacterial toxins can do, but also to add new functions, extending or changing the intracellular routes. It is possible to make conjugates or, more preferably, single-chain proteins that recognize cancer cells and deliver cargo inside the cells, even to the desired subcellular compartment. These findings offer new opportunities to deliver drugs/labels only to cancer cells and only to their site of action within the cells. The development of such dual-specificity vectors for targeting cancer cells is an attractive and potentially safer and more efficacious way of delivering drugs. We provide examples of this approach for delivering brain cancer therapeutics, using a specific biomarker on glioblastoma tumor cells.

C22-bronchial and T7-alveolar epithelial cell lines of the immortomouse are excellent murine cell culture model systems to study pulmonary peroxisome biology and metabolism.

PubMed

Karnati, Srikanth; Palaniswamy, Saranya; Alam, Mohammad Rashedul; Oruqaj, Gani; Stamme, Cordula; Baumgart-Vogt, Eveline

2016-03-01

In pulmonary research, temperature-sensitive immortalized cell lines derived from the lung of the "immortomouse" (H-2k(b)-tsA58 transgenic mouse), such as C22 club cells and T7 alveolar epithelial cells type II (AECII), are frequently used cell culture models to study CC10 metabolism and surfactant synthesis. Even though peroxisomes are highly abundant in club cells and AECII and might fulfill important metabolic functions therein, these organelles have never been investigated in C22 and T7 cells. Therefore, we have characterized the peroxisomal compartment and its associated gene transcription in these cell lines. Our results show that peroxisomes are highly abundant in C22 and T7 cells, harboring a common set of enzymes, however, exhibiting specific differences in protein composition and gene expression patterns, similar to the ones observed in club cells and AECII in situ in the lung. C22 cells contain a lower number of larger peroxisomes, whereas T7 cells possess more numerous tubular peroxisomes, reflected also by higher levels of PEX11 proteins. Moreover, C22 cells harbor relatively higher amounts of catalase and antioxidative enzymes in distinct subcellular compartments, whereas T7 cells exhibit higher levels of ABCD3 and plasmalogen synthesizing enzymes as well as nuclear receptors of the PPAR family. This study suggest that the C22 and T7 cell lines of the immortomouse lung are useful models to study the regulation and metabolic function of the peroxisomal compartment and its alterations by paracrine factors in club cells and AECII.

Transfer of Free Polymannose-type Oligosaccharides from the Cytosol to Lysosomes in Cultured Human Hepatocellular Carcinoma HEPG2 Cells

PubMed Central

Saint-Pol, Agnès; Bauvy, Chantal; Codogno, Patrice; Moore, Stuart E.H.

1997-01-01

Large, free polymannose oligosaccharides generated during glycoprotein biosynthesis rapidly appear in the cytosol of HepG2 cells where they undergo processing by a cytosolic endo H–like enzyme and a mannosidase to yield the linear isomer of Man5GlcNAc (Man[α1-2]Man[α1-2]Man[α1-3][Man α1-6]Man[β14]GlcNAc). Here we have examined the fate of these partially trimmed oligosaccharides in intact HepG2 cells. Subsequent to pulse–chase incubations with d-[2- 3H]mannose followed by permeabilization of cells with streptolysin O free oligosaccharides were isolated from the resulting cytosolic and membrane-bound compartments. Control pulse–chase experiments revealed that total cellular free oligosaccharides are lost from HepG2 cells with a half-life of 3–4 h. In contrast use of the vacuolar H+/ATPase inhibitor, concanamycin A, stabilized total cellular free oligosaccharides and enabled us to demonstrate a translocation of partially trimmed oligosaccharides from the cytosol into a membrane-bound compartment. This translocation process was unaffected by inhibitors of autophagy but inhibited if cells were treated with either 100 μM swainsonine, which provokes a cytosolic accumulation of large free oligosaccharides bearing 8-9 residues of mannose, or agents known to reduce cellular ATP levels which lead to the accumulation of the linear isomer of Man5GlcNAc in the cytosol. Subcellular fractionation studies on Percoll density gradients revealed that the cytosol-generated linear isomer of Man5GlcNAc is degraded in a membrane-bound compartment that cosediments with lysosomes. PMID:9008702

Transfer of free polymannose-type oligosaccharides from the cytosol to lysosomes in cultured human hepatocellular carcinoma HepG2 cells.

PubMed

Saint-Pol, A; Bauvy, C; Codogno, P; Moore, S E

1997-01-13

Large, free polymannose oligosaccharides generated during glycoprotein biosynthesis rapidly appear in the cytosol of HepG2 cells where they undergo processing by a cytosolic endo H-like enzyme and a mannosidase to yield the linear isomer of Man5GlcNAc (Man[alpha 1-2]Man[alpha 1-2]Man[alpha 1-3][Man alpha 1-6]Man[beta 1-4] GlcNAc). Here we have examined the fate of these partially trimmed oligosaccharides in intact HepG2 cells. Subsequent to pulse-chase incubations with D-[2-3H]mannose followed by permeabilization of cells with streptolysin O free oligosaccharides were isolated from the resulting cytosolic and membrane-bound compartments. Control pulse-chase experiments revealed that total cellular free oligosaccharides are lost from HepG2 cells with a half-life of 3-4 h. In contrast use of the vacuolar H+/ATPase inhibitor, concanamycin A, stabilized total cellular free oligosaccharides and enabled us to demonstrate a translocation of partially trimmed oligosaccharides from the cytosol into a membrane-bound compartment. This translocation process was unaffected by inhibitors of autophagy but inhibited if cells were treated with either 100 microM swainsonine, which provokes a cytosolic accumulation of large free oligosaccharides bearing 8-9 residues of mannose, or agents known to reduce cellular ATP levels which lead to the accumulation of the linear isomer of Man5GlcNAc in the cytosol. Subcellular fractionation studies on Percoll density gradients revealed that the cytosol-generated linear isomer of Man5GlcNAc is degraded in a membrane-bound compartment that cosediments with lysosomes.

K+ transporter AtCHX17 with its hydrophilic C tail localizes to membranes of the secretory/endocytic system: role in reproduction and seed set.

PubMed

Chanroj, Salil; Padmanaban, Senthilkumar; Czerny, Daniel D; Jauh, Guang-Yuh; Sze, Heven

2013-07-01

The importance of sorting proteins and wall materials to their destination is critical for plant growth and development, though the machinery orchestrating membrane trafficking is poorly understood. Transporters that alter the environment across endomembrane compartments are thought to be important players. Using Escherichia coli and yeast, we previously showed that several Arabidopsis Cation/H(+) eXchanger (AtCHX) members were K(+) transporters with a role in pH homeostasis, though their subcellular location and biological roles in plants are unclear. Co-expression of markers with CHX16, CHX17, CHX18, or CHX19 tagged with a fluorescent protein indicated these transporters associated with plasma membrane (PM) and post-Golgi compartments. Under its native promoter, AtCHX17(1-820)-GFP localized to prevacuolar compartment (PVC) and to PM in roots. Brefeldin A diminished AtCHX17-GFP fluorescence at PM, whereas wortmannin caused formation of GFP-labeled ring-like structures, suggesting AtCHX17 trafficked among PVC, vacuole and PM. AtCHX17(1-472) lacking its carboxylic tail did not associate with PVC or PM in plant cells. Single chx17 mutant or higher-order mutants showed normal root growth and vegetative development. However, quadruple (chx16chx17chx18chx19) mutants were reduced in frequency and produced 50%-70% fewer seeds, indicating overlapping roles of several AtCHX17-related transporters in reproduction and/or seed development. Together, our results suggest that successful reproduction and seed development depend on the ability to regulate cation and pH homeostasis by AtCHX17-like transporters on membranes that traffic in the endocytic and/or secretory pathways.

Toward Intracellular Targeted Delivery of Cancer Therapeutics

PubMed Central

Pandya, Hetal; Debinski, Waldemar

2013-01-01

A number of anti-cancer drugs have their targets localized to particular intracellular compartments. These drugs reach the targets mainly through diffusion, dependent on biophysical and biochemical forces that allow cell penetration. This means that both cancer cells and normal cells will be subjected to such diffusion; hence many of these drugs, like chemotherapeutics, are potentially toxic and the concentration achieved at the site of their action is often suboptimal. The same relates to radiation that indiscriminately affects normal and diseased cells. However, nature-designed systems enable compounds present in the extracellular environment to end up inside the cell and even travel to more specific intracellular compartments. For example, viruses and bacterial toxins can more or less specifically recognize eukaryotic cells, enter these cells, and direct some protein portions to designated intracellular areas. These phenomena have led to creative thinking, such as employing viruses or bacterial toxins for cargo delivery to cells and, more specifically, to cancer cells. Proteins can be genetically engineered in order to not only mimic what viruses and bacterial toxins can do, but also to add new functions, extending or changing the intracellular routes. It is possible to make conjugates or, more preferably, single-chain proteins that recognize cancer cells and deliver cargo inside the cells, even to the desired subcellular compartment. These findings offer new opportunities to deliver drugs/labels only to cancer cells and only to their site of action within the cells. The development of such dual-specificity vectors for targeting cancer cells is an attractive and potentially safer and more efficacious way of delivering drugs. We provide examples of this approach for delivering brain cancer therapeutics, using a specific biomarker on glioblastoma tumor cells. PMID:22671766

Mitochondrial energy metabolism of rat hippocampus after treatment with the antidepressants desipramine and fluoxetine.

PubMed

Villa, Roberto Federico; Ferrari, Federica; Bagini, Laura; Gorini, Antonella; Brunello, Nicoletta; Tascedda, Fabio

2017-07-15

Alterations in mitochondrial functions have been hypothesized to participate in the pathogenesis of depression, because brain bioenergetic abnormalities have been detected in depressed patients by neuroimaging in vivo studies. However, this hypothesis is not clearly demonstrated in experimental studies: some suggest that antidepressants are inhibitors of mitochondrial metabolism, while others observe the opposite. In this study, the effects of 21-day treatment with desipramine (15 mg/kg) and fluoxetine (10 mg/kg) were examined on the energy metabolism of rat hippocampus, evaluating the catalytic activity of regulatory enzymes of mitochondrial energy-yielding metabolic pathways. Because of the micro-heterogeneity of brain mitochondria, we have distinguished between (a) non-synaptic mitochondria (FM) of neuronal perikaryon (post-synaptic compartment) and (b) intra-synaptic light (LM) and heavy (HM) mitochondria (pre-synaptic compartment). Desipramine and fluoxetine changed the catalytic activity of specific enzymes in the different types of mitochondria: (a) in FM, both drugs enhanced cytochrome oxidase and glutamate dehydrogenase, (b) in LM, the overall bioenergetics was unaffected and (c) in HM only desipramine increased malate dehydrogenase and decreased the activities of Electron Transport Chain Complexes. These results integrate the pharmacodynamic features of desipramine and fluoxetine at subcellular level, overcoming the previous conflicting data about the effects of antidepressants on brain energy metabolism, mainly referred to whole brain homogenates or to bulk of cerebral mitochondria. With the differentiation in non-synaptic and intra-synaptic mitochondria, this study demonstrates that desipramine and fluoxetine lead to adjustments in the mitochondrial bioenergetics respect to the energy requirements of pre- and post-synaptic compartments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Protozoa enhance foraging efficiency of arbuscular mycorrhizal fungi for mineral nitrogen from organic matter in soil to the benefit of host plants.

PubMed

Koller, Robert; Rodriguez, Alia; Robin, Christophe; Scheu, Stefan; Bonkowski, Michael

2013-07-01

Dead organic matter (OM) is a major source of nitrogen (N) for plants. The majority of plants support N uptake by symbiosis with arbuscular mycorrhizal (AM) fungi. Mineralization of N is regulated by microfauna, in particular, protozoa grazing on bacteria. We hypothesized that AM fungi and protozoa interactively facilitate plant N nutrition from OM. In soil systems consisting of an OM patch and a root compartment, plant N uptake and consequences for plant carbon (C) allocation were investigated using stable isotopes. Protozoa mobilized N by consuming bacteria, and the mobilized N was translocated via AM fungi to the host plant. The presence of protozoa in both the OM and root compartment stimulated photosynthesis and the translocation of C from the host plant via AM fungi into the OM patch. This stimulated microbial activity in the OM patch, plant N uptake from OM and doubled plant growth. The results indicate that protozoa increase plant growth by both mobilization of N from OM and by protozoa-root interactions, resulting in increased C allocation to roots and into the rhizosphere, thereby increasing plant nutrient exploitation. Hence, mycorrhizal plants need to interact with protozoa to fully exploit N resources from OM. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Method and apparatus for sustaining viability of biological cells on a substrate

DOEpatents

McKnight, Timothy E.; Melechko, Anatoli V.; Simpson, Michael L.

2013-01-01

A method for the transient transformation of a living biological cell having an intact cell membrane defining an intracellular domain, and an apparatus for the transient transformation of biological cells. The method and apparatus include introducing a compartmentalized extracellular component fixedly attached to a cellular penetrant structure to the intracellular domain of the cell, wherein the cell is fixed in a predetermined location and wherein the component is expressed within in the cell while being retained within the compartment and wherein the compartment restricts the mobility and interactions of the component within the cell and prevents transference of the component to the cell.

Method and apparatus for sustaining viability of biological cells on a substrate

DOEpatents

McKnight, Timothy E [Greenback, TN; Melechko, Anatoli V [Oak Ridge, TN; Simpson, Michael L [Knoxville, TN

2011-12-13

A method for the transient transformation of a living biological cell having an intact cell membrane defining an intracellular domain, and an apparatus for the transient transformation of biological cells. The method and apparatus include introducing a compartmentalized extracellular component fixedly attached to a cellular penetrant structure to the intracellular domain of the cell, wherein the cell is fixed in a predetermined location and wherein the component is expressed within in the cell while being retained within the compartment and wherein the compartment restricts the mobility and interactions of the component within the cell and prevents transference of the component to the cell.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hay, J.; Schwender, J.

Computational simulation of large-scale biochemical networks can be used to analyze and predict the metabolic behavior of an organism, such as a developing seed. Based on the biochemical literature, pathways databases and decision rules defining reaction directionality we reconstructed bna572, a stoichiometric metabolic network model representing Brassica napus seed storage metabolism. In the highly compartmentalized network about 25% of the 572 reactions are transport reactions interconnecting nine subcellular compartments and the environment. According to known physiological capabilities of developing B. napus embryos, four nutritional conditions were defined to simulate heterotrophy or photoheterotrophy, each in combination with the availability of inorganicmore » nitrogen (ammonia, nitrate) or amino acids as nitrogen sources. Based on mathematical linear optimization the optimal solution space was comprehensively explored by flux variability analysis, thereby identifying for each reaction the range of flux values allowable under optimality. The range and variability of flux values was then categorized into flux variability types. Across the four nutritional conditions, approximately 13% of the reactions have variable flux values and 10-11% are substitutable (can be inactive), both indicating metabolic redundancy given, for example, by isoenzymes, subcellular compartmentalization or the presence of alternative pathways. About one-third of the reactions are never used and are associated with pathways that are suboptimal for storage synthesis. Fifty-seven reactions change flux variability type among the different nutritional conditions, indicating their function in metabolic adjustments. This predictive modeling framework allows analysis and quantitative exploration of storage metabolism of a developing B. napus oilseed.« less

A Plethora of Virulence Strategies Hidden Behind Nuclear Targeting of Microbial Effectors

PubMed Central

Rivas, Susana; Genin, Stéphane

2011-01-01

Plant immune responses depend on the ability to couple rapid recognition of the invading microbe to an efficient response. During evolution, plant pathogens have acquired the ability to deliver effector molecules inside host cells in order to manipulate cellular and molecular processes and establish pathogenicity. Following translocation into plant cells, microbial effectors may be addressed to different subcellular compartments. Intriguingly, a significant number of effector proteins from different pathogenic microorganisms, including viruses, oomycetes, fungi, nematodes, and bacteria, is targeted to the nucleus of host cells. In agreement with this observation, increasing evidence highlights the crucial role played by nuclear dynamics, and nucleocytoplasmic protein trafficking during a great variety of analyzed plant–pathogen interactions. Once in the nucleus, effector proteins are able to manipulate host transcription or directly subvert essential host components to promote virulence. Along these lines, it has been suggested that some effectors may affect histone packing and, thereby, chromatin configuration. In addition, microbial effectors may either directly activate transcription or target host transcription factors to alter their regular molecular functions. Alternatively, nuclear translocation of effectors may affect subcellular localization of their cognate resistance proteins in a process that is essential for resistance protein-mediated plant immunity. Here, we review recent progress in our field on the identification of microbial effectors that are targeted to the nucleus of host plant cells. In addition, we discuss different virulence strategies deployed by microbes, which have been uncovered through examination of the mechanisms that guide nuclear localization of effector proteins. PMID:22639625

Multiple-Localization and Hub Proteins

PubMed Central

Ota, Motonori; Gonja, Hideki; Koike, Ryotaro; Fukuchi, Satoshi

2016-01-01

Protein-protein interactions are fundamental for all biological phenomena, and protein-protein interaction networks provide a global view of the interactions. The hub proteins, with many interaction partners, play vital roles in the networks. We investigated the subcellular localizations of proteins in the human network, and found that the ones localized in multiple subcellular compartments, especially the nucleus/cytoplasm proteins (NCP), the cytoplasm/cell membrane proteins (CMP), and the nucleus/cytoplasm/cell membrane proteins (NCMP), tend to be hubs. Examinations of keywords suggested that among NCP, those related to post-translational modifications and transcription functions are the major contributors to the large number of interactions. These types of proteins are characterized by a multi-domain architecture and intrinsic disorder. A survey of the typical hub proteins with prominent numbers of interaction partners in the type revealed that most are either transcription factors or co-regulators involved in signaling pathways. They translocate from the cytoplasm to the nucleus, triggered by the phosphorylation and/or ubiquitination of intrinsically disordered regions. Among CMP and NCMP, the contributors to the numerous interactions are related to either kinase or ubiquitin ligase activity. Many of them reside on the cytoplasmic side of the cell membrane, and act as the upstream regulators of signaling pathways. Overall, these hub proteins function to transfer external signals to the nucleus, through the cell membrane and the cytoplasm. Our analysis suggests that multiple-localization is a crucial concept to characterize groups of hub proteins and their biological functions in cellular information processing. PMID:27285823

Determining the Roles of Inositol Trisphosphate Receptors in Neurodegeneration: Interdisciplinary Perspectives on a Complex Topic.

PubMed

Takada, Silvia Honda; Ikebara, Juliane Midori; de Sousa, Erica; Cardoso, Débora Sterzeck; Resende, Rodrigo Ribeiro; Ulrich, Henning; Rückl, Martin; Rüdiger, Sten; Kihara, Alexandre Hiroaki

2017-11-01

It is well known that calcium (Ca 2+ ) is involved in the triggering of neuronal death. Ca 2+ cytosolic levels are regulated by Ca 2+ release from internal stores located in organelles, such as the endoplasmic reticulum. Indeed, Ca 2+ transit from distinct cell compartments follows complex dynamics that are mediated by specific receptors, notably inositol trisphosphate receptors (IP3Rs). Ca 2+ release by IP3Rs plays essential roles in several neurological disorders; however, details of these processes are poorly understood. Moreover, recent studies have shown that subcellular location, molecular identity, and density of IP3Rs profoundly affect Ca 2+ transit in neurons. Therefore, regulation of IP3R gene products in specific cellular vicinities seems to be crucial in a wide range of cellular processes from neuroprotection to neurodegeneration. In this regard, microRNAs seem to govern not only IP3Rs translation levels but also subcellular accumulation. Combining new data from molecular cell biology with mathematical modelling, we were able to summarize the state of the art on this topic. In addition to presenting how Ca 2+ dynamics mediated by IP3R activation follow a stochastic regimen, we integrated a theoretical approach in an easy-to-apply, cell biology-coherent fashion. Following the presented premises and in contrast to previously tested hypotheses, Ca 2+ released by IP3Rs may play different roles in specific neurological diseases, including Alzheimer's disease and Parkinson's disease.

Endosome-Associated CRT1 Functions Early in Resistance Gene–Mediated Defense Signaling in Arabidopsis and Tobacco[W

PubMed Central

Kang, Hong-Gu; Oh, Chang-Sik; Sato, Masanao; Katagiri, Fumiaki; Glazebrook, Jane; Takahashi, Hideki; Kachroo, Pradeep; Martin, Gregory B.; Klessig, Daniel F.

2010-01-01

Resistance gene–mediated immunity confers protection against pathogen infection in a wide range of plants. A genetic screen for Arabidopsis thaliana mutants compromised for recognition of turnip crinkle virus previously identified CRT1, a member of the GHKL ATPase/kinase superfamily. Here, we demonstrate that CRT1 interacts with various resistance proteins from different structural classes, and this interaction is disrupted when these resistance proteins are activated. The Arabidopsis mutant crt1-2 crh1-1, which lacks CRT1 and its closest homolog, displayed compromised resistance to avirulent Pseudomonas syringae and Hyaloperonospora arabidopsidis. Additionally, resistance-associated hypersensitive cell death was suppressed in Nicotiana benthamiana silenced for expression of CRT1 homolog(s). Thus, CRT1 appears to be a general factor for resistance gene–mediated immunity. Since elevation of cytosolic calcium triggered by avirulent P. syringae was compromised in crt1-2 crh1-1 plants, but cell death triggered by Nt MEK2DD was unaffected in CRT1-silenced N. benthamiana, CRT1 likely functions at an early step in this pathway. Genome-wide transcriptome analysis led to identification of CRT1-Associated genes, many of which are associated with transport processes, responses to (a)biotic stress, and the endomembrane system. Confocal microscopy and subcellular fractionation revealed that CRT1 localizes to endosome-like vesicles, suggesting a key process in resistance protein activation/signaling occurs in this subcellular compartment. PMID:20332379

Dynamic subcellular partitioning of the nucleolar transcription factor TIF-IA under ribotoxic stress.

PubMed

Szymański, Jedrzej; Mayer, Christine; Hoffmann-Rohrer, Urs; Kalla, Claudia; Grummt, Ingrid; Weiss, Matthias

2009-07-01

TIF-IA is a basal transcription factor of RNA polymerase I (Pol I) that is a major target of the JNK2 signaling pathway in response to ribotoxic stress. Using advanced fluorescence microscopy and kinetic modeling we elucidated the subcellular localization of TIF-IA and its exchange dynamics between the nucleolus, nucleoplasm and cytoplasm upon ribotoxic stress. In steady state, the majority of (GFP-tagged) TIF-IA was in the cytoplasm and the nucleus, a minor portion (7%) localizing to the nucleoli. We observed a rapid shuttling of GFP-TIF-IA between the different cellular compartments with a mean residence time of approximately 130 s in the nucleus and only approximately 30 s in the nucleoli. The import rate from the cytoplasm to the nucleus was approximately 3-fold larger than the export rate, suggesting an importin/exportin-mediated transport rather than a passive diffusion. Upon ribotoxic stress, GFP-TIF-IA was released from the nucleoli with a half-time of approximately 24 min. Oxidative stress and inhibition of protein synthesis led to a relocation of GFP-TIF-IA with slower kinetics while osmotic stress had no effect. The observed relocation was much slower than the nucleo-cytoplasmic and nucleus-nucleolus exchange rates of GFP-TIF-IA, indicating a time-limiting step upstream of the JNK2 pathway. In support of this, time-course experiments on the activity of JNK2 revealed the activation of the JNK kinase as the rate-limiting step.

Subcellular Localization Screening of Colletotrichum higginsianum Effector Candidates Identifies Fungal Proteins Targeted to Plant Peroxisomes, Golgi Bodies, and Microtubules.

PubMed

Robin, Guillaume P; Kleemann, Jochen; Neumann, Ulla; Cabre, Lisa; Dallery, Jean-Félix; Lapalu, Nicolas; O'Connell, Richard J

2018-01-01

The genome of the hemibiotrophic anthracnose fungus, Colletotrichum higginsianum , encodes a large inventory of putative secreted effector proteins that are sequentially expressed at different stages of plant infection, namely appressorium-mediated penetration, biotrophy and necrotrophy. However, the destinations to which these proteins are addressed inside plant cells are unknown. In the present study, we selected 61 putative effector genes that are highly induced in appressoria and/or biotrophic hyphae. We then used Agrobacterium -mediated transformation to transiently express them as N -terminal fusions with fluorescent proteins in cells of Nicotiana benthamiana for imaging by confocal microscopy. Plant compartments labeled by the fusion proteins in N. benthamiana were validated by co-localization with specific organelle markers, by transient expression of the proteins in the true host plant, Arabidopsis thaliana , and by transmission electron microscopy-immunogold labeling. Among those proteins for which specific subcellular localizations could be verified, nine were imported into plant nuclei, three were imported into the matrix of peroxisomes, three decorated cortical microtubule arrays and one labeled Golgi stacks. Two peroxisome-targeted proteins harbored canonical C -terminal tripeptide signals for peroxisome import via the PTS1 (peroxisomal targeting signal 1) pathway, and we showed that these signals are essential for their peroxisome localization. Our findings provide valuable information about which host processes are potentially manipulated by this pathogen, and also reveal plant peroxisomes, microtubules, and Golgi as novel targets for fungal effectors.

An intrinsic DFF40/CAD endonuclease deficiency impairs oligonucleosomal DNA hydrolysis during caspase-dependent cell death: a common trait in human glioblastoma cells

PubMed Central

Sánchez-Osuna, María; Martínez-Escardó, Laura; Granados-Colomina, Carla; Martínez-Soler, Fina; Pascual-Guiral, Sònia; Iglesias-Guimarais, Victoria; Velasco, Roser; Plans, Gerard; Vidal, Noemi; Tortosa, Avelina; Barcia, Carlos; Bruna, Jordi; Yuste, Victor J.

2016-01-01

Background Glioblastoma (GBM) or grade IV astrocytoma is one of the most devastating human cancers. The loss of DFF40/CAD, the key endonuclease that triggers oligonucleosomal DNA fragmentation during apoptosis, has been linked to genomic instability and cell survival after radiation. Despite the near inevitability of GBM tumor recurrence after treatment, the relationship between DFF40/CAD and GBM remains unexplored. Methods We studied the apoptotic behavior of human GBM-derived cells after apoptotic insult. We analyzed caspase activation and the protein levels and subcellular localization of DFF40/CAD apoptotic endonuclease. DFF40/CAD was also evaluated in histological sections from astrocytic tumors and nontumoral human brain. Results We showed that GBM cells undergo incomplete apoptosis without generating oligonucleosomal DNA degradation despite the correct activation of executioner caspases. The major defect of GBM cells relied on the improper accumulation of DFF40/CAD at the nucleoplasmic subcellular compartment. Supporting this finding, DFF40/CAD overexpression allowed GBM cells to display oligonucleosomal DNA degradation after apoptotic challenge. Moreover, the analysis of histological slices from astrocytic tumors showed that DFF40/CAD immunoreactivity in tumoral GFAP-positive cells was markedly reduced when compared with nontumoral samples. Conclusions Our data highlight the low expression levels of DFF40/CAD and the absence of DNA laddering as common molecular traits in GBM. These findings could be of major importance for understanding the malignant behavior of remaining tumor cells after radiochemotherapy. PMID:26755073

Visualization of CD44 and CD133 in Normal Pancreas and Pancreatic Ductal Adenocarcinomas

PubMed Central

Immervoll, Heike; Hoem, Dag; Steffensen, Ole Johnny; Miletic, Hrvoje; Molven, Anders

2011-01-01

Tumor-initiating cells of pancreatic ductal adenocarcinoma (PDAC) have been isolated based on expression of either CD133 or CD44. The authors aimed to visualize pancreatic cells simultaneously expressing both these cell surface markers by employing the same antibodies commonly used in cell-sorting studies. Normal and diseased pancreatic tissue, including 51 PDAC cases, were analyzed. CD44 and CD133 expression was determined by immunohistochemical double staining on formalin-fixed material and subcellular protein distribution evaluated by immunofluorescence/confocal microscopy. In the normal pancreas, CD44 and CD133 were coexpressed in the centroacinar regions but in non-overlapping subcellular compartments. As expected, CD44 was found mainly basolaterally, whereas CD133 was present on the apical/endoluminal membrane. This was also the case in chronically inflamed/atrophic pancreatic tissue and in PDAC. In some malignant ducts, CD44 was found at the apical cell membrane adjacent to but never overlapping with CD133 expression. CD44 level was significantly associated with the patient’s lymph node status. In conclusion, a CD44+/CD133+ cell population does exist in the normal and neoplastic pancreas. The preferentially centroacinar localization of the doubly positive cells in the normal parenchyma suggests that this population could be of particular interest in attempts to identify tumor-initiating cells in PDAC. This article contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials. PMID:21411814

Subcellular Targeting of Methylmercury Lyase Enhances Its Specific Activity for Organic Mercury Detoxification in Plants1

PubMed Central

Bizily, Scott P.; Kim, Tehryung; Kandasamy, Muthugapatti K.; Meagher, Richard B.

2003-01-01

Methylmercury is an environmental pollutant that biomagnifies in the aquatic food chain with severe consequences for humans and other animals. In an effort to remove this toxin in situ, we have been engineering plants that express the bacterial mercury resistance enzymes organomercurial lyase MerB and mercuric ion reductase MerA. In vivo kinetics experiments suggest that the diffusion of hydrophobic organic mercury to MerB limits the rate of the coupled reaction with MerA (Bizily et al., 2000). To optimize reaction kinetics for organic mercury compounds, the merB gene was engineered to target MerB for accumulation in the endoplasmic reticulum and for secretion to the cell wall. Plants expressing the targeted MerB proteins and cytoplasmic MerA are highly resistant to organic mercury and degrade organic mercury at 10 to 70 times higher specific activity than plants with the cytoplasmically distributed wild-type MerB enzyme. MerB protein in endoplasmic reticulum-targeted plants appears to accumulate in large vesicular structures that can be visualized in immunolabeled plant cells. These results suggest that the toxic effects of organic mercury are focused in microenvironments of the secretory pathway, that these hydrophobic compartments provide more favorable reaction conditions for MerB activity, and that moderate increases in targeted MerB expression will lead to significant gains in detoxification. In summary, to maximize phytoremediation efficiency of hydrophobic pollutants in plants, it may be beneficial to target enzymes to specific subcellular environments. PMID:12586871

Immunocytochemical localization of chymase to cytoplasmic vesicles after rat peritoneal mast cell stimulation by compound 48/80.

PubMed

Login, G R; Aoki, M; Yamakawa, M; Lunardi, L O; Digenis, E C; Tanda, N; Schwartz, L B; Dvorak, A M

1997-10-01

The subcellular events responsible for release of mediators by mast cells may help to clarify roles for mast cells in health and disease. In this study we show that the granule-associated protease chymase is also within cytoplasmic vesicles in appropriately stimulated rat peritoneal mast cells. Rat peritoneal mast cells were recovered before or 1-10 sec after exposure to the secretogogue compound 48/80 (10 micrograms/ml) and then were examined by radioimmunoassay to quantify histamine release or were processed, using routine methods for postembedding immunoelectron microscopy, to identify the subcellular localization of chymase. In comparison to unstimulated cells, compound 48/80 stimulated cells in two independent experiments showed an increase (15%, 28%) in the surface area of the cell and a decrease (12%, 6%) in the surface area of the total granule compartment before degranulation channel formation. These global cellular changes occurred in a background of transient but significant (p < 0.01) increases in the area and number of chymase-immunoreactive vesicles per microns2 cytoplasm. These changes were detectable at 5 or 7 sec after stimulation with compound 48/80 but returned to near prestimulation levels by 9 or 10 sec after addition of compound 48/80 (total cumulative histamine release was 28% by 8 sec and 47% by 14 sec). These observations suggest that vesicles participate in the early stages of regulated secretion of chymase from rat peritoneal mast cells.

Subcellular localization and compartmentation of thiamine derivatives in rat brain.

PubMed

Bettendorff, L; Wins, P; Lesourd, M

1994-05-26

The subcellular distribution of thiamine derivatives in rat brain was studied. Thiamine diphosphate content was highest in the mitochondrial and synaptosomal fractions, and lowest in microsomal, myelin and cytosolic fractions. Only 3-5% of total thiamine diphosphate was bound to transketolase, a cytosolic enzyme. Thiamine triphosphate was barely detectable in the microsomal and cytosolic fraction, but synaptosomes were slightly enriched in this compound compared to the crude homogenate. Both myelin and mitochondrial fractions contained significant amounts of thiamine triphosphate. In order to estimate the relative turnover rates of these compounds, the animals received an intraperitoneal injection of either [14C]thiamine or [14C]sulbutiamine (isobutyrylthiamine disulfide) 1 h before decapitation. The specific radioactivities of thiamine compounds found in the brain decreased in the order: thiamine > thiamine triphosphate > thiamine monophosphate > thiamine diphosphate. Incorporation of radioactivity into thiamine triphosphate was more marked with [14C]sulbutiamine than with [14C]thiamine. The highest specific radioactivity of thiamine diphosphate was found in the cytosolic fraction of the brain, though this pool represents less than 10% of total thiamine diphosphate. Cytosolic thiamine diphosphate had a twice higher specific radioactivity when [14C]sulbutiamine was used as precursor compared with thiamine though no significant differences were found in the other cellular compartments. Our results suggest the existence of two thiamine diphosphate pools: the bound cofactor pool is essentially mitochondrial and has a low turnover; a much smaller cytosolic pool (6-7% of total TDP) of high turnover is the likely precursor of thiamine triphosphate.

Protein phosphatase 2A: a highly regulated family of serine/threonine phosphatases implicated in cell growth and signalling.

PubMed Central

Janssens, V; Goris, J

2001-01-01

Protein phosphatase 2A (PP2A) comprises a family of serine/threonine phosphatases, minimally containing a well conserved catalytic subunit, the activity of which is highly regulated. Regulation is accomplished mainly by members of a family of regulatory subunits, which determine the substrate specificity, (sub)cellular localization and catalytic activity of the PP2A holoenzymes. Moreover, the catalytic subunit is subject to two types of post-translational modification, phosphorylation and methylation, which are also thought to be important regulatory devices. The regulatory ability of PTPA (PTPase activator), originally identified as a protein stimulating the phosphotyrosine phosphatase activity of PP2A, will also be discussed, alongside the other regulatory inputs. The use of specific PP2A inhibitors and molecular genetics in yeast, Drosophila and mice has revealed roles for PP2A in cell cycle regulation, cell morphology and development. PP2A also plays a prominent role in the regulation of specific signal transduction cascades, as witnessed by its presence in a number of macromolecular signalling modules, where it is often found in association with other phosphatases and kinases. Additionally, PP2A interacts with a substantial number of other cellular and viral proteins, which are PP2A substrates, target PP2A to different subcellular compartments or affect enzyme activity. Finally, the de-regulation of PP2A in some specific pathologies will be touched upon. PMID:11171037

Akt Substrate of 160 kD Regulates Na+,K+-ATPase Trafficking in Response to Energy Depletion and Renal Ischemia

PubMed Central

Alves, Daiane S.; Thulin, Gunilla; Loffing, Johannes; Kashgarian, Michael

2015-01-01

Renal ischemia and reperfusion injury causes loss of renal epithelial cell polarity and perturbations in tubular solute and fluid transport. Na+,K+-ATPase, which is normally found at the basolateral plasma membrane of renal epithelial cells, is internalized and accumulates in intracellular compartments after renal ischemic injury. We previously reported that the subcellular distribution of Na+,K+-ATPase is modulated by direct binding to Akt substrate of 160 kD (AS160), a Rab GTPase-activating protein that regulates the trafficking of glucose transporter 4 in response to insulin and muscle contraction. Here, we investigated the effect of AS160 on Na+,K+-ATPase trafficking in response to energy depletion. We found that AS160 is required for the intracellular accumulation of Na+,K+-ATPase that occurs in response to energy depletion in cultured epithelial cells. Energy depletion led to dephosphorylation of AS160 at S588, which was required for the energy depletion–induced accumulation of Na,K-ATPase in intracellular compartments. In AS160-knockout mice, the effects of renal ischemia on the distribution of Na+,K+-ATPase were substantially reduced in the epithelial cells of distal segments of the renal tubules. These data demonstrate that AS160 has a direct role in linking the trafficking of Na+,K+-ATPase to the energy state of renal epithelial cells. PMID:25788531

RNA imaging: tracking in real-time RNA transport in neurons using molecular beacons and confocal microscopy.

PubMed

Zepeda, Angélica; Arias, Clorinda; Flores-Jasso, Fabian; Vaca, Luis

2013-01-01

RNAs are present within eukaryotic cells and are involved in several biological processes. RNA transport within cell compartments is important for proper cell function. To understand in depth the cellular processes in which RNA is involved requires a method that reveals RNA localization in real time in a sub-cellular context in living cells. In this protocol we describe a method for imaging RNA in living cells and in particular in neuronal cultures based on cell microinjection of molecular beacons in conjunction with confocal microscopy. This methodology overcomes some of the main obstacles for imaging RNA in live cells since microinjection allows the delivery of the probe to a desired cellular compartment and MBs bind with high specificity to its target RNA without inhibiting its function. The proper design of the MBs is essential to obtain RNA-MB association at the temperature of the cell cytosol. MBs design with other purposes in mind (such as PCR experiments) have a design that facilitates association to its target at high temperatures, rendering them unsuitable for live cell imaging. Using the methodology described in this chapter allows the study of RNA transport to different regions of neurons and may be combined with the tagging of proteins of interest to measure co-transport of the protein and the RNA to different cellular regions. Copyright © 2013 Elsevier Inc. All rights reserved.

The endoplasmic reticulum is a hub to sort proteins toward unconventional traffic pathways and endosymbiotic organelles.

PubMed

Bellucci, Michele; De Marchis, Francesca; Pompa, Andrea

2017-12-18

The discovery that much of the extracellular proteome in eukaryotic cells consists of proteins lacking a signal peptide, which cannot therefore enter the secretory pathway, has led to the identification of alternative protein secretion routes bypassing the Golgi apparatus. However, proteins harboring a signal peptide for translocation into the endoplasmic reticulum can also be transported along these alternative routes, which are still far from being well elucidated in terms of the molecular machineries and subcellular/intermediate compartments involved. In this review, we first try to provide a definition of all the unconventional protein secretion pathways in eukaryotic cells, as those pathways followed by proteins directed to an 'external space' bypassing the Golgi, where 'external space' refers to the extracellular space plus the lumen of the secretory route compartments and the inner space of mitochondria and plastids. Then, we discuss the role of the endoplasmic reticulum in sorting proteins toward unconventional traffic pathways in plants. In this regard, various unconventional pathways exporting proteins from the endoplasmic reticulum to the vacuole, plasma membrane, apoplast, mitochondria, and plastids are described, including the short routes followed by the proteins resident in the endoplasmic reticulum. © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Purification of intact chloroplasts from marine plant Posidonia oceanica suitable for organelle proteomics.

PubMed

Piro, Amalia; Serra, Ilia Anna; Spadafora, Antonia; Cardilio, Monica; Bianco, Linda; Perrotta, Gaetano; Santos, Rui; Mazzuca, Silvia

2015-12-01

Posidonia oceanica is a marine angiosperm, or seagrass, adapted to grow to the underwater life from shallow waters to 50 m depth. This raises questions of how their photosynthesis adapted to the attenuation of light through the water column and leads to the assumption that biochemistry and metabolism of the chloroplast are the basis of adaptive capacity. In the present study, we described a protocol that was adapted from those optimized for terrestrial plants, to extract chloroplasts from as minimal tissue as possible. We obtained the best balance between tissue amount/intact chloroplasts yield using one leaf from one plant. After isopynic separations, the chloroplasts purity and integrity were evaluated by biochemical assay and using a proteomic approach. Chloroplast proteins were extracted from highly purified organelles and resolved by 1DE SDS-PAGE. Proteins were sequenced by nLC-ESI-IT-MS/MS of 1DE gel bands and identified against NCBInr green plant databases, Dr. Zompo database for seagrasses in a local customized dataset. The curated localization of proteins in sub-plastidial compartments (i.e. envelope, stroma and thylakoids) was retrieved in the AT_CHLORO database. This purification protocol and the validation of compartment markers may serve as basis for sub-cellular proteomics in P. oceanica and other seagrasses. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zucchini-dependent piRNA processing is triggered by recruitment to the cytoplasmic processing machinery

PubMed Central

Rogers, Alicia K.; Situ, Kathy; Perkins, Edward M.; Toth, Katalin Fejes

2017-01-01

The piRNA pathway represses transposable elements in the gonads and thereby plays a vital role in protecting the integrity of germline genomes of animals. Mature piRNAs are processed from longer transcripts, piRNA precursors (pre-piRNAs). In Drosophila, processing of pre-piRNAs is initiated by piRNA-guided Slicer cleavage or the endonuclease Zucchini (Zuc). As Zuc does not have any sequence or structure preferences in vitro, it is not known how piRNA precursors are selected and channeled into the Zuc-dependent processing pathway. We show that a heterologous RNA that lacks complementary piRNAs is processed into piRNAs upon recruitment of several piRNA pathway factors. This processing requires Zuc and the helicase Armitage (Armi). Aubergine (Aub), Argonaute 3 (Ago3), and components of the nuclear RDC complex, which are required for normal piRNA biogenesis in germ cells, are dispensable. Our approach allows discrimination of proteins involved in the transcription and export of piRNA precursors from components required for the cytoplasmic processing steps. piRNA processing correlates with localization of the substrate RNA to nuage, a distinct membraneless cytoplasmic compartment, which surrounds the nucleus of germ cells, suggesting that sequestration of RNA to this subcellular compartment is both necessary and sufficient for selecting piRNA biogenesis substrates. PMID:29021243

Identification and subcellular localization of porcine deltacoronavirus accessory protein NS6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Puxian; Fang, Liurong; Liu, Xiaorong

Porcine deltacoronavirus (PDCoV) is an emerging swine enteric coronavirus. Accessory proteins are genus-specific for coronavirus, and two putative accessory proteins, NS6 and NS7, are predicted to be encoded by PDCoV; however, this remains to be confirmed experimentally. Here, we identified the leader-body junction sites of NS6 subgenomic RNA (sgRNA) and found that the actual transcription regulatory sequence (TRS) utilized by NS6 is non-canonical and is located upstream of the predicted TRS. Using the purified NS6 from an Escherichia coli expression system, we obtained two anti-NS6 monoclonal antibodies that could detect the predicted NS6 in cells infected with PDCoV or transfectedmore » with NS6-expressing plasmids. Further studies revealed that NS6 is always localized in the cytoplasm of PDCoV-infected cells, mainly co-localizing with the endoplasmic reticulum (ER) and ER-Golgi intermediate compartments, as well as partially with the Golgi apparatus. Together, our results identify the NS6 sgRNA and demonstrate its expression in PDCoV-infected cells. -- Highlights: •The leader-body fusion site of NS6 sgRNA is identified. •NS6 sgRNA uses a non-canonical transcription regulatory sequence (TRS). •NS6 can be expressed in PDCoV-infected cell. •NS6 predominantly localize to the ER complex and ER-Golgi intermediate compartment.« less

SuMoToRI, an Ecophysiological Model to Predict Growth and Sulfur Allocation and Partitioning in Oilseed Rape (Brassica napus L.) Until the Onset of Pod Formation

PubMed Central

Brunel-Muguet, Sophie; Mollier, Alain; Kauffmann, François; Avice, Jean-Christophe; Goudier, Damien; Sénécal, Emmanuelle; Etienne, Philippe

2015-01-01

Sulfur (S) nutrition in rapeseed (Brassica napus L.) is a major concern for this high S-demanding crop, especially in the context of soil S oligotrophy. Therefore, predicting plant growth, S plant allocation (between the plant’s compartments) and S pool partitioning (repartition of the mobile-S vs. non-mobile-S fractions) until the onset of reproductive phase could help in the diagnosis of S deficiencies during the early stages. For this purpose, a process-based model, SuMoToRI (Sulfur Model Toward Rapeseed Improvement), was developed up to the onset of pod formation. The key features rely on (i) the determination of the S requirements used for growth (structural and metabolic functions) through critical S dilution curves and (ii) the estimation of a mobile pool of S that is regenerated by daily S uptake and remobilization from senescing leaves. This study describes the functioning of the model and presents the model’s calibration and evaluation. SuMoToRI was calibrated and evaluated with independent datasets from greenhouse experiments under contrasting S supply conditions. It is run with a small number of parameters with generic values, except in the case of the radiation use efficiency, which was shown to be modulated by S supply. The model gave satisfying predictions of the dynamics of growth, S allocation between compartments and S partitioning, such as the mobile-S fraction in the leaves, which is an indicator of the remobilization potential toward growing sinks. The mechanistic features of SuMoToRI provide a process-based framework that has enabled the description of the S remobilizing process in a species characterized by senescence during the vegetative phase. We believe that this model structure could be useful for modeling S dynamics in other arable crops that have similar senescence-related characteristics. PMID:26635825

Effect of radio-frequency electromagnetic radiations (RF-EMR) on passive avoidance behaviour and hippocampal morphology in Wistar rats.

PubMed

Narayanan, Sareesh Naduvil; Kumar, Raju Suresh; Potu, Bhagath Kumar; Nayak, Satheesha; Bhat, P Gopalakrishna; Mailankot, Maneesh

2010-05-01

The interaction of mobile phone radio-frequency electromagnetic radiation (RF-EMR) with the brain is a serious concern of our society. We evaluated the effect of RF-EMR from mobile phones on passive avoidance behaviour and hippocampal morphology in rats. Healthy male albino Wistar rats were exposed to RF-EMR by giving 50 missed calls (within 1 hour) per day for 4 weeks, keeping a GSM (0.9 GHz/1.8 GHz) mobile phone in vibratory mode (no ring tone) in the cage. After the experimental period, passive avoidance behaviour and hippocampal morphology were studied. Passive avoidance behaviour was significantly affected in mobile phone RF-EMR-exposed rats demonstrated as shorter entrance latency to the dark compartment when compared to the control rats. Marked morphological changes were also observed in the CA(3) region of the hippocampus of the mobile phone-exposed rats in comparison to the control rats. Mobile phone RF-EMR exposure significantly altered the passive avoidance behaviour and hippocampal morphology in rats.

Phosphorylation-mediated RNA/peptide complex coacervation as a model for intracellular liquid organelles

NASA Astrophysics Data System (ADS)

Aumiller, William M.; Keating, Christine D.

2016-02-01

Biological cells are highly organized, with numerous subcellular compartments. Phosphorylation has been hypothesized as a means to control the assembly/disassembly of liquid-like RNA- and protein-rich intracellular bodies, or liquid organelles, that lack delimiting membranes. Here, we demonstrate that charge-mediated phase separation, or complex coacervation, of RNAs with cationic peptides can generate simple model liquid organelles capable of reversibly compartmentalizing biomolecules. Formation and dissolution of these liquid bodies was controlled by changes in peptide phosphorylation state using a kinase/phosphatase enzyme pair. The droplet-generating phase transition responded to modification of even a single serine residue. Electrostatic interactions between the short cationic peptides and the much longer polyanionic RNAs drove phase separation. Coacervates were also formed on silica beads, a primitive model for localization at specific intracellular sites. This work supports phosphoregulation of complex coacervation as a viable mechanism for dynamic intracellular compartmentalization in membraneless organelles.

Intrinsically disordered proteins aggregate at fungal cell-to-cell channels and regulate intercellular connectivity.

PubMed

Lai, Julian; Koh, Chuan Hock; Tjota, Monika; Pieuchot, Laurent; Raman, Vignesh; Chandrababu, Karthik Balakrishna; Yang, Daiwen; Wong, Limsoon; Jedd, Gregory

2012-09-25

Like animals and plants, multicellular fungi possess cell-to-cell channels (septal pores) that allow intercellular communication and transport. Here, using a combination of MS of Woronin body-associated proteins and a bioinformatics approach that identifies related proteins based on composition and character, we identify 17 septal pore-associated (SPA) proteins that localize to the septal pore in rings and pore-centered foci. SPA proteins are not homologous at the primary sequence level but share overall physical properties with intrinsically disordered proteins. Some SPA proteins form aggregates at the septal pore, and in vitro assembly assays suggest aggregation through a nonamyloidal mechanism involving mainly α-helical and disordered structures. SPA loss-of-function phenotypes include excessive septation, septal pore degeneration, and uncontrolled Woronin body activation. Together, our data identify the septal pore as a complex subcellular compartment and focal point for the assembly of unstructured proteins controlling diverse aspects of intercellular connectivity.

On the role of electrostatics in protein-protein interactions

NASA Astrophysics Data System (ADS)

Zhang, Zhe; Witham, Shawn; Alexov, Emil

2011-06-01

The role of electrostatics in protein-protein interactions and binding is reviewed in this paper. A brief outline of the computational modeling, in the framework of continuum electrostatics, is presented and the basic electrostatic effects occurring upon the formation of the complex are discussed. The effect of the salt concentration and pH of the water phase on protein-protein binding free energy is demonstrated which indicates that the increase of the salt concentration tends to weaken the binding, an observation that is attributed to the optimization of the charge-charge interactions across the interface. It is pointed out that the pH-optimum (pH of optimal binding affinity) varies among the protein-protein complexes, and perhaps is a result of their adaptation to particular subcellular compartments. The similarities and differences between hetero- and homo-complexes are outlined and discussed with respect to the binding mode and charge complementarity.

Plakins in striated muscle.

PubMed

Boyer, Justin G; Bernstein, Marija A; Boudreau-Larivière, Céline

2010-03-01

Striated muscle cells contain numerous architectural proteins that contribute to the function of muscle as generators of mechanical force. Among these proteins are crosslinkers belonging to the plakin family, namely plectin, microtubule-actin crosslinking factor (ACF7/MACF1), bullous pemphigoid antigen 1 (Bpag1/dystonin), and desmoplakin. These plakin family members, in particular plectin and Bpag1/dystonin, exist as several isoforms. The domain organization of these plakin variants dictates their subcellular location and the proteins with which they interact. Several studies suggest that plakins exert unique functions within various compartments of the muscle cell including the sarcolemma, the sarcomere, both neuromuscular and myotendinous junctions in skeletal muscle, and the intercalated discs in cardiac muscle. Plakins may also regulate the cellular placement and function of specific organelles, notably the nucleus, mitochondria, Golgi apparatus, and sarcoplasmic reticulum. Here we review and summarize our current knowledge of the function of plakins in striated muscle cells.

Glucosylated pH-sensitive liposomes as potential drug delivery systems.

PubMed

Giansanti, Luisa; Mauceri, Alessandro; Galantini, Luciano; Altieri, Barbara; Piozzi, Antonella; Mancini, Giovanna

2016-10-01

The inclusion of pH-sensitive components in liposome formulations can allow a more controlled and efficient release in response to low pH typical of some pathological tissues and/or subcellular compartments. On the other hand decorating the surface of liposomes with sugar moieties attributes to lipid vesicles specificity toward lectins, sugar-binding proteins overexpressed in many tumor tissues. A novel multifunctional pH-sensitive glucosylated amphiphile was synthesized and characterized as pure aggregate component and in mixtures with a natural phospholipid. The comparison of the properties of the new glucosylated amphiphile with respect to those of a previously described cationic structural analogue demonstrates that the pH-sensitivity can strongly affect drug release, lipid organization, as well as the exposure of the glucose residues on liposome surface and their ability to interact with Concanavalin A, a plant lectin used as model system. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Interplay Between Protein Homeostasis Networks in Protein Aggregation and Proteotoxicity

PubMed Central

Douglas, Peter M.; Cyr, Douglas M.

2010-01-01

The misfolding and aggregation of disease proteins is characteristic of numerous neurodegenerative diseases. Particular neuronal populations are more vulnerable to proteotoxicity while others are more apt to tolerate the misfolding and aggregation of disease proteins. Thus, the cellular environment must play a significant role in determining whether disease proteins are converted into toxic or benign forms. The endomembrane network of eukaryotes divides the cell into different subcellular compartments that possess distinct sets of molecular chaperones and protein interaction networks. Chaperones act as agonists and antagonists of disease protein aggregation to prevent the accumulation of toxic intermediates in the aggregation pathway. Interacting partners can also modulate the conformation and localization of disease proteins and thereby influence proteotoxicity. Thus, interplay between these protein homeostasis network components can modulate the self-association of disease proteins and determine whether they elicit a toxic or benign outcome. PMID:19768782

Chimeric green fluorescent protein-aequorin as bioluminescent Ca2+ reporters at the single-cell level

PubMed Central

Baubet, Valérie; Le Mouellic, Hervé; Campbell, Anthony K.; Lucas-Meunier, Estelle; Fossier, Philippe; Brûlet, Philippe

2000-01-01

Monitoring calcium fluxes in real time could help to understand the development, the plasticity, and the functioning of the central nervous system. In jellyfish, the chemiluminescent calcium binding aequorin protein is associated with the green fluorescent protein and a green bioluminescent signal is emitted upon Ca2+ stimulation. We decided to use this chemiluminescence resonance energy transfer between the two molecules. Calcium-sensitive bioluminescent reporter genes have been constructed by fusing green fluorescent protein and aequorin, resulting in much more light being emitted. Chemiluminescent and fluorescent activities of these fusion proteins have been assessed in mammalian cells. Cytosolic Ca2+ increases were imaged at the single-cell level with a cooled intensified charge-coupled device camera. This bifunctional reporter gene should allow the investigation of calcium activities in neuronal networks and in specific subcellular compartments in transgenic animals. PMID:10860991

Bacterial effectors target the plant cell nucleus to subvert host transcription.

PubMed

Canonne, Joanne; Rivas, Susana

2012-02-01

In order to promote virulence, Gram-negative bacteria have evolved the ability to inject so-called type III effector proteins into host cells. The plant cell nucleus appears to be a subcellular compartment repeatedly targeted by bacterial effectors. In agreement with this observation, mounting evidence suggests that manipulation of host transcription is a major strategy developed by bacteria to counteract plant defense responses. It has been suggested that bacterial effectors may adopt at least three alternative, although not mutually exclusive, strategies to subvert host transcription. T3Es may (1) act as transcription factors that directly activate transcription in host cells, (2) affect histone packing and chromatin configuration, and/or (3) target host transcription factor activity. Here, we provide an overview on how all these strategies may lead to host transcriptional re-programming and, as a result, to improved bacterial multiplication inside plant cells.

Protein Composition of Trypanosoma brucei Mitochondrial Membranes

PubMed Central

Acestor, Nathalie; Panigrahi, Aswini K.; Ogata, Yuko; Anupama, Atashi; Stuart, Kenneth D.

2010-01-01

Mitochondria consist of four compartments, outer membrane, intermembrane space, inner membrane and matrix; each harboring specific functions and structures. In this study, we used mass spectrometry (LC-MS/MS) to characterize the protein composition of Trypanosoma brucei mitochondrial membranes, which were enriched by different biochemical fractionation techniques. The analyses identified 202 proteins that contain one or more transmembrane domain(s) and/or positive GRAVY scores. Of these, various criteria were used to assign 72 proteins to mitochondrial membranes with high confidence, and 106 with moderate to low confidence. The sub-cellular localization of a selected subset of 13 membrane assigned proteins was confirmed by tagging and immunofluorescence analysis. While most proteins assigned to mitochondrial membrane have putative roles in metabolic, energy generating, and transport processes, ~50% have no known function. These studies result in a comprehensive profile of the composition and sub-organellar location of proteins in the T. brucei mitochondrion thus, providing useful information on mitochondrial functions. PMID:19834910

Intravital multiphoton photoconversion with a cell membrane dye.

PubMed

Turcotte, Raphaël; Wu, Juwell W; Lin, Charles P

2017-02-01

Photoconversion, an irreversible shift in a fluorophore emission spectrum after light exposure, is a powerful tool for marking cellular and subcellular compartments and tracking their dynamics in vivo. This paper reports on the photoconversion properties of Di-8-ANEPPS, a commercially available membrane dye. When illuminated with near-infrared femtosecond laser pulses, Di-8-ANEPPS undergoes multiphoton photoconversion as indicated by the supralinear dependence of the conversion rate ρ pc on the incident power (ρpc∝Iexc2.27), and by the ability to photoconvert a thin optical section in a three-dimensional matrix. The characteristic emission spectrum changed from red to blue, and ratiometric analysis on single cells in vitro revealed a 65-fold increase in the blue to red wavelength ratio after photoconversion. The spectral shift is preserved in vivo for hours, making Di-8-ANEPPS a useful dye for intravital cell marking and tracking applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On the role of electrostatics on protein-protein interactions

PubMed Central

Zhang, Zhe; Witham, Shawn; Alexov, Emil

2011-01-01

The role of electrostatics on protein-protein interactions and binding is reviewed in this article. A brief outline of the computational modeling, in the framework of continuum electrostatics, is presented and basic electrostatic effects occurring upon the formation of the complex are discussed. The role of the salt concentration and pH of the water phase on protein-protein binding free energy is demonstrated and indicates that the increase of the salt concentration tends to weaken the binding, an observation that is attributed to the optimization of the charge-charge interactions across the interface. It is pointed out that the pH-optimum (pH of optimal binding affinity) varies among the protein-protein complexes, and perhaps is a result of their adaptation to particular subcellular compartment. At the end, the similarities and differences between hetero- and homo-complexes are outlined and discussed with respect to the binding mode and charge complementarity. PMID:21572182

Applications of fiber-optics-based nanosensors to drug discovery.

PubMed

Vo-Dinh, Tuan; Scaffidi, Jonathan; Gregas, Molly; Zhang, Yan; Seewaldt, Victoria

2009-08-01

Fiber-optic nanosensors are fabricated by heating and pulling optical fibers to yield sub-micron diameter tips and have been used for in vitro analysis of individual living mammalian cells. Immobilization of bioreceptors (e.g., antibodies, peptides, DNA) selective to targeting analyte molecules of interest provides molecular specificity. Excitation light can be launched into the fiber, and the resulting evanescent field at the tip of the nanofiber can be used to excite target molecules bound to the bioreceptor molecules. The fluorescence or surface-enhanced Raman scattering produced by the analyte molecules is detected using an ultra-sensitive photodetector. This article provides an overview of the development and application of fiber-optic nanosensors for drug discovery. The nanosensors provide minimally invasive tools to probe subcellular compartments inside single living cells for health effect studies (e.g., detection of benzopyrene adducts) and medical applications (e.g., monitoring of apoptosis in cells treated with anticancer drugs).

The role of nanotechnology in single-cell detection: a review.

PubMed

Wang, Changling; Zhang, Yuxiang; Xia, Mingdian; Zhu, Xingxi; Qi, Shitao; Shen, Huaqiang; Liu, Tiebing; Tang, Liming

2014-10-01

Biological processes in single cells, such as signal transduction, DNA duplication, and protein synthesis and trafficking, occur in subcellular compartments at nanoscale level. Achieving high spatial-temporal resolution, high sensitivity, and high specificity in single-cell detection poses a great challenge. Nanotechnology, which has been widely applied in the fields of medicine, electronics, biomaterials, and energy production, has the potential to provide solutions for single-cell detection. Here we present a review of the use of nanotechnology in single-cell detection over the past two decades. First, we review the main areas of scientific interest, including morphology, ion concentration, DNA, RNA, protein, intracellular temperature, elements, and mechanical properties. Second, four categories of application of nanotechnology to single-cell detection are described: nanomanipulation, nanodevices, nanomaterials as labels, and nano Secondary ion mass spectrometry. Finally, the prospects and future trends in single-cell detection and analysis are discussed.

Detection of Diverse and High Molecular Weight Nesprin-1 and Nesprin-2 Isoforms Using Western Blotting.

PubMed

Carthew, James; Karakesisoglou, Iakowos

2016-01-01

Heavily utilized in cell and molecular biology, western blotting is considered a crucial technique for the detection and quantification of proteins within complex mixtures. In particular, the detection of members of the nesprin (nuclear envelope spectrin repeat protein) family has proven difficult to analyze due to their substantial isoform diversity, molecular weight variation, and the sheer size of both nesprin-1 and nesprin-2 giant protein variants (>800 kDa). Nesprin isoforms contain distinct domain signatures, perform differential cytoskeletal associations, occupy different subcellular compartments, and vary in their tissue expression profiles. This structural and functional variance highlights the need to distinguish between the full range of proteins within the nesprin protein family, allowing for greater understanding of their specific roles in cell biology and disease. Herein, we describe a western blotting protocol modified for the detection of low to high molecular weight (50-1000 kDa) nesprin proteins.

Cortical Interneuron Subtypes Vary in Their Axonal Action Potential Properties

PubMed Central

Casale, Amanda E.; Foust, Amanda J.; Bal, Thierry

2015-01-01

The role of interneurons in cortical microcircuits is strongly influenced by their passive and active electrical properties. Although different types of interneurons exhibit unique electrophysiological properties recorded at the soma, it is not yet clear whether these differences are also manifested in other neuronal compartments. To address this question, we have used voltage-sensitive dye to image the propagation of action potentials into the fine collaterals of axons and dendrites in two of the largest cortical interneuron subtypes in the mouse: fast-spiking interneurons, which are typically basket or chandelier neurons; and somatostatin containing interneurons, which are typically regular spiking Martinotti cells. We found that fast-spiking and somatostatin-expressing interneurons differed in their electrophysiological characteristics along their entire dendrosomatoaxonal extent. The action potentials generated in the somata and axons, including axon collaterals, of somatostatin-expressing interneurons are significantly broader than those generated in the same compartments of fast-spiking inhibitory interneurons. In addition, action potentials back-propagated into the dendrites of somatostatin-expressing interneurons much more readily than fast-spiking interneurons. Pharmacological investigations suggested that axonal action potential repolarization in both cell types depends critically upon Kv1 channels, whereas the axonal and somatic action potentials of somatostatin-expressing interneurons also depend on BK Ca2+-activated K+ channels. These results indicate that the two broad classes of interneurons studied here have expressly different subcellular physiological properties, allowing them to perform unique computational roles in cortical circuit operations. SIGNIFICANCE STATEMENT Neurons in the cerebral cortex are of two major types: excitatory and inhibitory. The proper balance of excitation and inhibition in the brain is critical for its operation. Neurons contain three main compartments: dendritic, somatic, and axonal. How the neurons receive information, process it, and pass on new information depends upon how these three compartments operate. While it has long been assumed that axons are simply for conducting information from the cell body to the synapses, here we demonstrate that the axons of different types of interneurons, the inhibitory cells, possess differing electrophysiological properties. This result implies that differing types of interneurons perform different tasks in the cortex, not only through their anatomical connections, but also through how their axons operate. PMID:26609152

A mathematical model of single target site location by Brownian movement in subcellular compartments.

PubMed

Kuthan, Hartmut

2003-03-07

The location of distinct sites is mandatory for many cellular processes. In the subcompartments of the cell nucleus, only very small numbers of diffusing macromolecules and specific target sites of some types may be present. In this case, we are faced with the Brownian movement of individual macromolecules and their "random search" for single/few specific target sites, rather than bulk-averaged diffusion and multiple sites. In this article, I consider the location of a distant central target site, e.g. a globular protein, by individual macromolecules executing unbiased (i.e. drift-free) random walks in a spherical compartment. For this walk-and-capture model, the closed-form analytic solution of the first passage time probability density function (p.d.f.) has been obtained as well as the first and second moment. In the limit of a large ratio of the radii of the spherical diffusion space and central target, well-known relations for the variance and the first two moments for the exponential p.d.f. were found to hold with high accuracy. These calculations reinforce earlier numerical results and Monte Carlo simulations. A major implication derivable from the model is that non-directed random movement is an effective means for locating single sites in submicron-sized compartments, even when the diffusion coefficients are comparatively small and the diffusing species are present in one copy only. These theoretical conclusions are underscored numerically for effective diffusion constants ranging from 0.5 to 10.0 microm(2) s(-1), which have been reported for a couple of nuclear proteins in their physiological environment. Spherical compartments of submicron size are, for example, the Cajal bodies (size: 0.1-1.0 microm), which are present in 1-5 copies in the cell nucleus. Within a small Cajal body of radius 0.1 microm a single diffusing protein molecule (with D=0.5 microm(2) s(-1)) would encounter a medium-sized protein of radius 2.5 nm within 1 s with a probability near certainty (p=0.98).

Extensor Pollicis Longus Injury in Addition to De Quervain’s with Text Messaging on Mobile Phones

PubMed Central

Kumar, Bhaskaranand; Bhat, Anil K; Venugopal, Anand

2014-01-01

Objective: To do a clinical and ultrasonic evaluation of subjects with thumb pain with text messaging. Background: Thumbs are commonly used for text messaging, which are not as well designed for fine manipulative or dexterous work. Repetitive use as in text messaging can lead to the injury to the tendons of the thumb. Materials and Methods: Ninety eight students with symptoms of Repetitive Strain Type of injuries of the thumb were selected from a survey and evaluated both clinically and by ultrasound analysis of the musculotendinous unit of the thumb to note changes due to excessive use of the mobile phone. Age and sex matched controls were also subjected to ultrasound evaluation. Results: Clinical examination showed positive Finkelstein test in 40% of the cases, significant reduction in the lateral and tip pinch strengths in the cases. Ultrasound detected changes in the first and the third compartments in 19% of the cases. Conclusion: Isolated cases of pain in the thumb have been reported but this study noted changes both clinically and by ultrasound in the tendons of the thumb. These changes should be taken as warning signs of possible subclinical changes taking place in the soft tissues of the thumb in these subjects due to repetitive use of mobile phones and thus, making them prone for developing painful Musculoskeletal Disorders. Application: Repetitive use of mobile phones for text messaging can lead to the damage of Extensor pollicis longus of the thumb in addition to the tendons of the first compartment of the wrist. PMID:25584249

Analysis of subcellular sized particles. Capillary electrophoresis with post-column laser-induced fluorescence detection versus flow cytometry.

PubMed

Poe, Bobby G; Navratil, Marian; Arriaga, Edgar A

2006-12-29

Flow cytometry (FCM) and more recently capillary electrophoresis with post-column laser-induced fluorescence detection (CE-LIF) have both been used for subcellular particle analysis but their analytical performance has not been compared. In this work, we compare a commercial FCM with an in-house built CE-LIF instrument using fluorescently labeled microspheres and isolated mitochondria. As evidenced by the relative standard deviation (RSD) of the individual fluorescence intensities, FCM is two-fold better than CE-LIF for microspheres with > or =1.5 x 10(6) molecules of equivalent soluble fluorescein (MESF). However, FCM has a comparatively low signal-to-noise ratio (S/N) and high RSD for microspheres with <1.5 x 10(6) MESF. CE-LIF, on the other hand, produces S/N ratios that are >25 times higher than FCM for all the microspheres tested and a lower RSD for microspheres with <1.5 x 10(6) MESF. When 10-N-nonyl acridine orange (NAO)-labeled mitochondria are analyzed, the S/N ratios of both techniques are similar. This appears to result from photobleaching of NAO-labeled mitochondria as they are detected by the LIF detector of the CE-LIF instrument. Both techniques have a niche in subcellular analysis; FCM has the advantage of collecting data for thousands of particles quickly, whereas CE-LIF consumes less than a nanoliter of sample and provides the electrophoretic mobility for individual particles.

Intracellular trafficking of silicon particles and logic-embedded vectors

NASA Astrophysics Data System (ADS)

Ferrati, Silvia; Mack, Aaron; Chiappini, Ciro; Liu, Xuewu; Bean, Andrew J.; Ferrari, Mauro; Serda, Rita E.

2010-08-01

Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon particles to be optimized for specific applications such as vascular targeting and avoidance of biological barriers commonly found between the site of drug injection and the final destination. In this study, the intracellular trafficking of unloaded carrier silicon particles and carrier particles loaded with secondary iron oxide nanoparticles was investigated. Following cellular uptake, membrane-encapsulated silicon particles migrated to the perinuclear region of the cell by a microtubule-driven mechanism. Surface charge, shape (spherical and hemispherical) and size (1.6 and 3.2 μm) of the particle did not alter the rate of migration. Maturation of the phagosome was associated with an increase in acidity and acquisition of markers of late endosomes and lysosomes. Cellular uptake of iron oxide nanoparticle-loaded silicon particles resulted in sorting of the particles and trafficking to unique destinations. The silicon carriers remained localized in phagosomes, while the second stage iron oxide nanoparticles were sorted into multi-vesicular bodies that dissociated from the phagosome into novel membrane-bound compartments. Release of iron from the cells may represent exocytosis of iron oxide nanoparticle-loaded vesicles. These results reinforce the concept of multi-functional nanocarriers, in which different particles are able to perform specific tasks, in order to deliver single- or multi-component payloads to specific sub-cellular compartments.Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon particles to be optimized for specific applications such as vascular targeting and avoidance of biological barriers commonly found between the site of drug injection and the final destination. In this study, the intracellular trafficking of unloaded carrier silicon particles and carrier particles loaded with secondary iron oxide nanoparticles was investigated. Following cellular uptake, membrane-encapsulated silicon particles migrated to the perinuclear region of the cell by a microtubule-driven mechanism. Surface charge, shape (spherical and hemispherical) and size (1.6 and 3.2 μm) of the particle did not alter the rate of migration. Maturation of the phagosome was associated with an increase in acidity and acquisition of markers of late endosomes and lysosomes. Cellular uptake of iron oxide nanoparticle-loaded silicon particles resulted in sorting of the particles and trafficking to unique destinations. The silicon carriers remained localized in phagosomes, while the second stage iron oxide nanoparticles were sorted into multi-vesicular bodies that dissociated from the phagosome into novel membrane-bound compartments. Release of iron from the cells may represent exocytosis of iron oxide nanoparticle-loaded vesicles. These results reinforce the concept of multi-functional nanocarriers, in which different particles are able to perform specific tasks, in order to deliver single- or multi-component payloads to specific sub-cellular compartments. Electronic supplementary information (ESI) available: Confocal microscopy image showing internalized negative particles, and movie of the intracellular migration of silicon particles. See DOI: 10.1039/c0nr00227e

Effects of motor patterns on water-soluble and membrane proteins and cholinesterase activity in subcellular fractions of rat brain tissue

NASA Technical Reports Server (NTRS)

Pevzner, L. Z.; Venkov, L.; Cheresharov, L.

1980-01-01

Albino rats were kept for a year under conditions of daily motor load or constant hypokinesia. An increase in motor activity results in a rise in the acetylcholinesterase activity determined in the synaptosomal and purified mitochondrial fractions while hypokinesia induces a pronounced decrease in this enzyme activity. The butyrylcholinesterase activity somewhat decreases in the synaptosomal fraction after hypokinesia but does not change under the motor load pattern. Motor load causes an increase in the amount of synaptosomal water-soluble proteins possessing an intermediate electrophoretic mobility and seem to correspond to the brain-specific protein 14-3-2. In the synaptosomal fraction the amount of membrane proteins with a low electrophoretic mobility and with the cholinesterase activity rises. Hypokinesia, on the contrary, decreases the amount of these membrane proteins.

Agent-Based Modeling of Mitochondria Links Sub-Cellular Dynamics to Cellular Homeostasis and Heterogeneity.

PubMed

Dalmasso, Giovanni; Marin Zapata, Paula Andrea; Brady, Nathan Ryan; Hamacher-Brady, Anne

2017-01-01

Mitochondria are semi-autonomous organelles that supply energy for cellular biochemistry through oxidative phosphorylation. Within a cell, hundreds of mobile mitochondria undergo fusion and fission events to form a dynamic network. These morphological and mobility dynamics are essential for maintaining mitochondrial functional homeostasis, and alterations both impact and reflect cellular stress states. Mitochondrial homeostasis is further dependent on production (biogenesis) and the removal of damaged mitochondria by selective autophagy (mitophagy). While mitochondrial function, dynamics, biogenesis and mitophagy are highly-integrated processes, it is not fully understood how systemic control in the cell is established to maintain homeostasis, or respond to bioenergetic demands. Here we used agent-based modeling (ABM) to integrate molecular and imaging knowledge sets, and simulate population dynamics of mitochondria and their response to environmental energy demand. Using high-dimensional parameter searches we integrated experimentally-measured rates of mitochondrial biogenesis and mitophagy, and using sensitivity analysis we identified parameter influences on population homeostasis. By studying the dynamics of cellular subpopulations with distinct mitochondrial masses, our approach uncovered system properties of mitochondrial populations: (1) mitochondrial fusion and fission activities rapidly establish mitochondrial sub-population homeostasis, and total cellular levels of mitochondria alter fusion and fission activities and subpopulation distributions; (2) restricting the directionality of mitochondrial mobility does not alter morphology subpopulation distributions, but increases network transmission dynamics; and (3) maintaining mitochondrial mass homeostasis and responding to bioenergetic stress requires the integration of mitochondrial dynamics with the cellular bioenergetic state. Finally, (4) our model suggests sources of, and stress conditions amplifying, cell-to-cell variability of mitochondrial morphology and energetic stress states. Overall, our modeling approach integrates biochemical and imaging knowledge, and presents a novel open-modeling approach to investigate how spatial and temporal mitochondrial dynamics contribute to functional homeostasis, and how subcellular organelle heterogeneity contributes to the emergence of cell heterogeneity.

Agent-Based Modeling of Mitochondria Links Sub-Cellular Dynamics to Cellular Homeostasis and Heterogeneity

PubMed Central

Dalmasso, Giovanni; Marin Zapata, Paula Andrea; Brady, Nathan Ryan; Hamacher-Brady, Anne

2017-01-01

Mitochondria are semi-autonomous organelles that supply energy for cellular biochemistry through oxidative phosphorylation. Within a cell, hundreds of mobile mitochondria undergo fusion and fission events to form a dynamic network. These morphological and mobility dynamics are essential for maintaining mitochondrial functional homeostasis, and alterations both impact and reflect cellular stress states. Mitochondrial homeostasis is further dependent on production (biogenesis) and the removal of damaged mitochondria by selective autophagy (mitophagy). While mitochondrial function, dynamics, biogenesis and mitophagy are highly-integrated processes, it is not fully understood how systemic control in the cell is established to maintain homeostasis, or respond to bioenergetic demands. Here we used agent-based modeling (ABM) to integrate molecular and imaging knowledge sets, and simulate population dynamics of mitochondria and their response to environmental energy demand. Using high-dimensional parameter searches we integrated experimentally-measured rates of mitochondrial biogenesis and mitophagy, and using sensitivity analysis we identified parameter influences on population homeostasis. By studying the dynamics of cellular subpopulations with distinct mitochondrial masses, our approach uncovered system properties of mitochondrial populations: (1) mitochondrial fusion and fission activities rapidly establish mitochondrial sub-population homeostasis, and total cellular levels of mitochondria alter fusion and fission activities and subpopulation distributions; (2) restricting the directionality of mitochondrial mobility does not alter morphology subpopulation distributions, but increases network transmission dynamics; and (3) maintaining mitochondrial mass homeostasis and responding to bioenergetic stress requires the integration of mitochondrial dynamics with the cellular bioenergetic state. Finally, (4) our model suggests sources of, and stress conditions amplifying, cell-to-cell variability of mitochondrial morphology and energetic stress states. Overall, our modeling approach integrates biochemical and imaging knowledge, and presents a novel open-modeling approach to investigate how spatial and temporal mitochondrial dynamics contribute to functional homeostasis, and how subcellular organelle heterogeneity contributes to the emergence of cell heterogeneity. PMID:28060865

NADPH Oxidase Is Internalized by Clathrin-coated Pits and Localizes to a Rab27A/B GTPase-regulated Secretory Compartment in Activated Macrophages*

PubMed Central

Ejlerskov, Patrick; Christensen, Dan Ploug; Beyaie, David; Burritt, James B.; Paclet, Marie-Helene; Gorlach, Agnes; van Deurs, Bo; Vilhardt, Frederik

2012-01-01

Here, we report that activation of different types of tissue macrophages, including microglia, by lipopolysaccharide (LPS) or GM-CSF stimulation correlates with the quantitative redistribution of NADPH oxidase (cyt b558) from the plasma membrane to an intracellular stimulus-responsive storage compartment. Cryo-immunogold labeling of gp91phox and CeCl3 cytochemistry showed the presence of gp91phox and oxidant production in numerous small (<100 nm) vesicles. Cell homogenization and sucrose gradient centrifugation in combination with transferrin-HRP/DAB ablation showed that more than half of cyt b558 is present in fractions devoid of endosomal markers, which is supported by morphological evidence to show that the cyt b558-containing compartment is distinct from endosomes or biosynthetic organelles. Streptolysin-O-mediated guanosine 5′-3-O-(thio)triphosphate loading of Ra2 microglia caused exocytosis of a major complement of cyt b558 under conditions where lysosomes or endosomes were not mobilized. We establish phagocytic particles and soluble mediators ATP, TNFα, and CD40L as physiological inducers of cyt b558 exocytosis to the cell surface, and by shRNA knockdown, we identify Rab27A/B as positive or negative regulators of vesicular mobilization to the phagosome or the cell surface, respectively. Exocytosis was followed by clathrin-dependent internalization of cyt b558, which could be blocked by a dominant negative mutant of the clathrin-coated pit-associated protein Eps15. Re-internalized cyt b558 did not reach lysosomes but associated with recycling endosomes and undefined vesicular elements. In conclusion, cyt b558 depends on clathrin for internalization, and in activated macrophages NADPH oxidase occupies a Rab27A/B-regulated secretory compartment, which allows rapid agonist-induced redistribution of superoxide production in the cell. PMID:22157766

Chemistry and Biology in Femtoliter and Picoliter Volume Droplets

PubMed Central

Chiu, Daniel T.; Lorenz, Robert M.

2009-01-01

Conspectus The basic unit of any biological system is the cell, and malfunctions at the single-cell level can result in devastating diseases; in cancer metastasis, for example, a single cell seeds the formation of a distant tumor. Although tiny, a cell is a highly heterogeneous and compartmentalized structure: proteins, lipids, RNA, and small-molecule metabolites constantly traffic among intracellular organelles. Gaining detailed information about the spatiotemporal distribution of these biomolecules is crucial to our understanding of cellular function and dysfunction. To access this information, we need sensitive tools that are capable of extracting comprehensive biochemical information from single cells and subcellular organelles. In this Account, we outline our approach and highlight our progress towards mapping the spatiotemporal organization of information flow in single cells. Our technique is centered on the use of femtoliter- and picoliter-sized droplets as nanolabs for manipulating single cells and subcellular compartments. We have developed a single-cell nanosurgical technique for isolating select subcellular structures from live cells, a capability that is needed for the high-resolution manipulation and chemical analysis of single cells. Our microfluidic approaches for generating single femtoliter-sized droplets on demand include both pressure and electric field methods; we have also explored a design for the on-demand generation of multiple aqueous droplets to increase throughput. Droplet formation is only the first step in a sequence that requires manipulation, fusion, transport, and analysis. Optical approaches provide the most convenient and precise control over the formed droplets with our technology platform; we describe aqueous droplet manipulation with optical vortex traps, which enable the remarkable ability to dynamically “tune” the concentration of the contents. Integration of thermoelectric manipulations with these techniques affords further control. The amount of chemical information that can be gleaned from single cells and organelles is critically dependent on the methods available for analyzing droplet contents. We describe three techniques we have developed: (i) droplet encapsulation, rapid cell lysis, and fluorescence-based single-cell assays, (ii) physical sizing of the subcellular organelles and nanoparticles in droplets, and (iii) capillary electrophoresis (CE) analysis of droplet contents. For biological studies, we are working to integrate the different components of our technology into a robust, automated device; we are also addressing an anticipated need for higher throughput. With progress in these areas, we hope to cement our technique as a new tool for studying single cells and organelles with unprecedented molecular detail. PMID:19260732

[Atraumatic dislocation in mobile-bearing total knee arthroplasty: two case reports].

PubMed

Schuh, A; Hönle, W

2007-10-01

Atraumatic dislocation following total knee arthroplasty (TKA) is a rare condition. Severe complications after dislocation are lesion of the vascular-nerve bundle, compartment syndrome or amputation. The benefit of TKA with mobile-bearing are an improvement of the range of motion and better articulation. In comparison to fixed-bearing TKA there is the risk of dislocation or breakage of the polyethylene insert. We present two cases with dislocation following TKA with mobile-bearing. In both cases preoperatively there was a significant weakening of the function of the quadriceps muscle. During revision of the TKA severe damage with multiple scratches of the polyethylene onlay could be detected. The damage of the PE onlay could especially be found at the tibial aspect. Follow-up showed an uneventful course after conversion to fixed-bearing polyethylen component. In cases of dislocation following TKA with mobile-bearing operative revision is recommended to exchange the damaged PE onlay and prevent increased wear. TKA with mobile-bearing should be reserved only for cases with a good quadriceps muscle function.

Protein localization as a principal feature of the etiology and comorbidity of genetic diseases

PubMed Central

Park, Solip; Yang, Jae-Seong; Shin, Young-Eun; Park, Juyong; Jang, Sung Key; Kim, Sanguk

2011-01-01

Proteins targeting the same subcellular localization tend to participate in mutual protein–protein interactions (PPIs) and are often functionally associated. Here, we investigated the relationship between disease-associated proteins and their subcellular localizations, based on the assumption that protein pairs associated with phenotypically similar diseases are more likely to be connected via subcellular localization. The spatial constraints from subcellular localization significantly strengthened the disease associations of the proteins connected by subcellular localizations. In particular, certain disease types were more prevalent in specific subcellular localizations. We analyzed the enrichment of disease phenotypes within subcellular localizations, and found that there exists a significant correlation between disease classes and subcellular localizations. Furthermore, we found that two diseases displayed high comorbidity when disease-associated proteins were connected via subcellular localization. We newly explained 7584 disease pairs by using the context of protein subcellular localization, which had not been identified using shared genes or PPIs only. Our result establishes a direct correlation between protein subcellular localization and disease association, and helps to understand the mechanism of human disease progression. PMID:21613983

GLUT4 Retention in Adipocytes Requires Two Intracellular Insulin-regulated Transport Steps

PubMed Central

Zeigerer, Anja; Lampson, Michael A.; Karylowski, Ola; Sabatini, David D.; Adesnik, Milton; Ren, Mindong; McGraw, Timothy E.

2002-01-01

Insulin regulates glucose uptake into fat and muscle by modulating the distribution of the GLUT4 glucose transporter between the surface and interior of cells. The GLUT4 trafficking pathway overlaps with the general endocytic recycling pathway, but the degree and functional significance of the overlap are not known. In this study of intact adipocytes, we demonstrate, by using a compartment-specific fluorescence-quenching assay, that GLUT4 is equally distributed between two intracellular pools: the transferrin receptor-containing endosomes and a specialized compartment that excludes the transferrin receptor. These pools of GLUT4 are in dynamic communication with one another and with the cell surface. Insulin-induced redistribution of GLUT4 to the surface requires mobilization of both pools. These data establish a role for the general endosomal system in the specialized, insulin-regulated trafficking of GLUT4. Trafficking through the general endosomal system is regulated by rab11. Herein, we show that rab11 is required for the transport of GLUT4 from endosomes to the specialized compartment and for the insulin-induced translocation to the cell surface, emphasizing the importance of the general endosomal pathway in the specialized trafficking of GLUT4. Based on these findings we propose a two-step model for GLUT4 trafficking in which the general endosomal recycling compartment plays a specialized role in the insulin-regulated traffic of GLUT4. This compartment-based model provides the framework for understanding insulin-regulated trafficking at a molecular level. PMID:12134080

GLUT4 retention in adipocytes requires two intracellular insulin-regulated transport steps.

PubMed

Zeigerer, Anja; Lampson, Michael A; Karylowski, Ola; Sabatini, David D; Adesnik, Milton; Ren, Mindong; McGraw, Timothy E

2002-07-01

Insulin regulates glucose uptake into fat and muscle by modulating the distribution of the GLUT4 glucose transporter between the surface and interior of cells. The GLUT4 trafficking pathway overlaps with the general endocytic recycling pathway, but the degree and functional significance of the overlap are not known. In this study of intact adipocytes, we demonstrate, by using a compartment-specific fluorescence-quenching assay, that GLUT4 is equally distributed between two intracellular pools: the transferrin receptor-containing endosomes and a specialized compartment that excludes the transferrin receptor. These pools of GLUT4 are in dynamic communication with one another and with the cell surface. Insulin-induced redistribution of GLUT4 to the surface requires mobilization of both pools. These data establish a role for the general endosomal system in the specialized, insulin-regulated trafficking of GLUT4. Trafficking through the general endosomal system is regulated by rab11. Herein, we show that rab11 is required for the transport of GLUT4 from endosomes to the specialized compartment and for the insulin-induced translocation to the cell surface, emphasizing the importance of the general endosomal pathway in the specialized trafficking of GLUT4. Based on these findings we propose a two-step model for GLUT4 trafficking in which the general endosomal recycling compartment plays a specialized role in the insulin-regulated traffic of GLUT4. This compartment-based model provides the framework for understanding insulin-regulated trafficking at a molecular level.

Arthroscopic partial meniscectomy of a posteriorly flipped superior leaflet in a horizontal medial meniscus tear using a posterior transseptal portal.

PubMed

Jang, Ki-Mo; Ahn, Jin Hwan; Wang, Joon Ho

2012-03-07

This article describes a case of an arthroscopic partial meniscectomy of a posteriorly flipped superior leaflet in a horizontal medial meniscus tear using the posterior transseptal portal. An arthroscopic partial meniscectomy for bucket handle or flap tears in medial or lateral compartments using ordinary portals is a relatively common procedure in irreparable cases. However, the posterior compartment of the knee is not readily accessible through ordinary arthroscopic portals. Therefore, it has been considered a blind spot. Through the posterior transseptal portal, surgeons can achieve excellent arthroscopic visualization of the posterior compartment and easily perform arthroscopic procedures of the posterior compartment of the knee. A 48-year-old woman presented with a 1-year history of pain in the medial aspect of the right knee joint. Preoperative magnetic resonance imaging revealed a thinning of the medial meniscus posterior horn in coronal images and a sharp-edged triangle arising from the medial meniscus posterior horn between the medial femoral condyle and medial meniscus posterior horn on sagittal images (flipped-over sign). During the arthroscopic procedure, we found that the flipped leaflet was displaced posteriorly and was not mobile between the medial femoral condyle and medial meniscus posterior horn. Partial meniscectomy for a posteriorly displaced fragment can be performed successfully using the posterior transseptal portal. The posterior transseptal portal is useful for an arthroscopic partial meniscectomy of a posteriorly flipped leaflet in the posterior compartment of the knee. Copyright 2012, SLACK Incorporated.

Vascular Nox (NADPH Oxidase) Compartmentalization, Protein Hyperoxidation, and Endoplasmic Reticulum Stress Response in Hypertension.

PubMed

Camargo, Livia L; Harvey, Adam P; Rios, Francisco J; Tsiropoulou, Sofia; Da Silva, Renée de Nazaré Oliveira; Cao, Zhenbo; Graham, Delyth; McMaster, Claire; Burchmore, Richard J; Hartley, Richard C; Bulleid, Neil; Montezano, Augusto C; Touyz, Rhian M

2018-07-01

Vascular Nox (NADPH oxidase)-derived reactive oxygen species and endoplasmic reticulum (ER) stress have been implicated in hypertension. However, relationships between these processes are unclear. We hypothesized that Nox isoforms localize in a subcellular compartment-specific manner, contributing to oxidative and ER stress, which influence the oxidative proteome and vascular function in hypertension. Nox compartmentalization (cell fractionation), O 2 - (lucigenin), H 2 O 2 (amplex red), reversible protein oxidation (sulfenylation), irreversible protein oxidation (protein tyrosine phosphatase, peroxiredoxin oxidation), and ER stress (PERK [protein kinase RNA-like endoplasmic reticulum kinase], IRE1α [inositol-requiring enzyme 1], and phosphorylation/oxidation) were studied in spontaneously hypertensive rat (SHR) vascular smooth muscle cells (VSMCs). VSMC proliferation was measured by fluorescence-activated cell sorting, and vascular reactivity assessed in stroke-prone SHR arteries by myography. Noxs were downregulated by short interfering RNA and pharmacologically. In SHR, Noxs were localized in specific subcellular regions: Nox1 in plasma membrane and Nox4 in ER. In SHR, oxidative stress was associated with increased protein sulfenylation and hyperoxidation of protein tyrosine phosphatases and peroxiredoxins. Inhibition of Nox1 (NoxA1ds), Nox1/4 (GKT137831), and ER stress (4-phenylbutyric acid/tauroursodeoxycholic acid) normalized SHR vascular reactive oxygen species generation. GKT137831 reduced IRE1α sulfenylation and XBP1 (X-box binding protein 1) splicing in SHR. Increased VSMC proliferation in SHR was normalized by GKT137831, 4-phenylbutyric acid, and STF083010 (IRE1-XBP1 disruptor). Hypercontractility in the stroke-prone SHR was attenuated by 4-phenylbutyric acid. We demonstrate that protein hyperoxidation in hypertension is associated with oxidative and ER stress through upregulation of plasmalemmal-Nox1 and ER-Nox4. The IRE1-XBP1 pathway of the ER stress response is regulated by Nox4/reactive oxygen species and plays a role in the hyperproliferative VSMC phenotype in SHR. Our study highlights the importance of Nox subcellular compartmentalization and interplay between cytoplasmic reactive oxygen species and ER stress response, which contribute to the VSMC oxidative proteome and vascular dysfunction in hypertension. © 2018 American Heart Association, Inc.

Vibrational imaging of newly synthesized proteins in live cells by stimulated Raman scattering microscopy

PubMed Central

Wei, Lu; Yu, Yong; Shen, Yihui; Wang, Meng C.; Min, Wei

2013-01-01

Synthesis of new proteins, a key step in the central dogma of molecular biology, has been a major biological process by which cells respond rapidly to environmental cues in both physiological and pathological conditions. However, the selective visualization of a newly synthesized proteome in living systems with subcellular resolution has proven to be rather challenging, despite the extensive efforts along the lines of fluorescence staining, autoradiography, and mass spectrometry. Herein, we report an imaging technique to visualize nascent proteins by harnessing the emerging stimulated Raman scattering (SRS) microscopy coupled with metabolic incorporation of deuterium-labeled amino acids. As a first demonstration, we imaged newly synthesized proteins in live mammalian cells with high spatial–temporal resolution without fixation or staining. Subcellular compartments with fast protein turnover in HeLa and HEK293T cells, and newly grown neurites in differentiating neuron-like N2A cells, are clearly identified via this imaging technique. Technically, incorporation of deuterium-labeled amino acids is minimally perturbative to live cells, whereas SRS imaging of exogenous carbon–deuterium bonds (C–D) in the cell-silent Raman region is highly sensitive, specific, and compatible with living systems. Moreover, coupled with label-free SRS imaging of the total proteome, our method can readily generate spatial maps of the quantitative ratio between new and total proteomes. Thus, this technique of nonlinear vibrational imaging of stable isotope incorporation will be a valuable tool to advance our understanding of the complex spatial and temporal dynamics of newly synthesized proteome in vivo. PMID:23798434

Different pools of glutamate receptors mediate sensitivity to ambient glutamate in the cochlear nucleus

PubMed Central

Yang, Yang

2015-01-01

Ambient glutamate plays an important role in pathological conditions, such as stroke, but its role during normal activity is not clear. In addition, it is not clear how ambient glutamate acts on glutamate receptors with varying affinities or subcellular localizations. To address this, we studied “endbulb of Held” synapses, which are formed by auditory nerve fibers onto bushy cells (BCs) in the anteroventral cochlear nucleus. When ambient glutamate was increased by applying the glutamate reuptake inhibitor TFB-TBOA, BCs depolarized as a result of activation of N-methyl-d-aspartate receptors (NMDARs) and group I metabotropic glutamate receptors (mGluRs). Application of antagonists against NMDARs (in 0 Mg2+) or mGluRs caused hyperpolarization, indicating that these receptors were bound by a tonic source of glutamate. AMPA receptors did not show these effects, consistent with their lower glutamate affinity. We also evaluated the subcellular localization of the receptors activated by ambient glutamate. The mGluRs were not activated by synaptic stimulation and thus appear to be exclusively extrasynaptic. By contrast, NMDARs in both synaptic and extrasynaptic compartments were activated by ambient glutamate, as shown using the use-dependent antagonist MK-801. Levels of ambient glutamate appeared to be regulated in a spike-independent manner, and glia likely play a major role. These low levels of ambient glutamate likely have functional consequences, as even low concentrations of TBOA caused significant increases in BC spiking following synaptic stimulation. These results indicate that normal resting potential appears to be poised in the region of maximal sensitivity to small changes in ambient glutamate. PMID:25855696

Image Processing for Bioluminescence Resonance Energy Transfer Measurement-BRET-Analyzer.

PubMed

Chastagnier, Yan; Moutin, Enora; Hemonnot, Anne-Laure; Perroy, Julie

2017-01-01

A growing number of tools now allow live recordings of various signaling pathways and protein-protein interaction dynamics in time and space by ratiometric measurements, such as Bioluminescence Resonance Energy Transfer (BRET) Imaging. Accurate and reproducible analysis of ratiometric measurements has thus become mandatory to interpret quantitative imaging. In order to fulfill this necessity, we have developed an open source toolset for Fiji- BRET-Analyzer -allowing a systematic analysis, from image processing to ratio quantification. We share this open source solution and a step-by-step tutorial at https://github.com/ychastagnier/BRET-Analyzer. This toolset proposes (1) image background subtraction, (2) image alignment over time, (3) a composite thresholding method of the image used as the denominator of the ratio to refine the precise limits of the sample, (4) pixel by pixel division of the images and efficient distribution of the ratio intensity on a pseudocolor scale, and (5) quantification of the ratio mean intensity and standard variation among pixels in chosen areas. In addition to systematize the analysis process, we show that the BRET-Analyzer allows proper reconstitution and quantification of the ratiometric image in time and space, even from heterogeneous subcellular volumes. Indeed, analyzing twice the same images, we demonstrate that compared to standard analysis BRET-Analyzer precisely define the luminescent specimen limits, enlightening proficient strengths from small and big ensembles over time. For example, we followed and quantified, in live, scaffold proteins interaction dynamics in neuronal sub-cellular compartments including dendritic spines, for half an hour. In conclusion, BRET-Analyzer provides a complete, versatile and efficient toolset for automated reproducible and meaningful image ratio analysis.

Cellular Pathway(S) of Antigen Processing and Presentation in Fish APC: Endosomal Involvement and Cell-Free Antigen Presentation

PubMed Central

Vallejo, Abbe N.; Miller, Norman W.; Harvey, Nancy E.; Cuchens, Marvin A.; Warr, Gregory W.

1992-01-01

Studies were conducted to address further the role(s) of antigen processing and presentation in the induction of immune responses in a phylogenetically lower vertebrate, specifically a teleost, the channel catfish. In particular, studies were aimed at determining the subcellular compartments involved in antigen degradation by channel catfish antigen-presenting cells (APC) as well as ascertaining the reexpression of immunogenic peptides on the surfaces of APC. The results showed that exogenous protein antigens were actively endocytosed by APC as detected by flow cytometry. Use of radiolabeled antigen and subcellular fractionation protocols also showed that antigen localized in endosomes/lysosomes. Furthermore, there was an apparent redistribution of antigen between these organelles and the plasma membrane during the course of antigen pulsing. Functional assays for the induction of in vitro antigen-specific proliferation of immune catfish peripheral blood leukocytes (PBL) showed that membrane preparations from antigen-pulsed autologous APC were highly stimulatory. The magnitude of responses elicited with such membrane preparations was very similar to that of PBL cultures stimulated with native antigen-pulsed and fixed intact APC or prefixed intact APC incubated with a peptide fragment of the nominal antigen. Current data further corroborate our previous findings that steps akin to antigen processing and presentation are clearly important in the induction of immune responses in lower vertebrates like fish, in a manner similar to that seen in mammalian systems. Consequently, it would appear that many immune functions among the diverse taxa of vertebrates are remarkably conserved. PMID:1343103

Regulation of Cell Physiology and Pathology by Protein S-Glutathionylation: Lessons Learned from the Cardiovascular System

PubMed Central

Pimentel, David; Haeussler, Dagmar Johanna; Matsui, Reiko; Burgoyne, Joseph Robert; Cohen, Richard Alan

2012-01-01

Abstract Significance: Reactive oxygen and nitrogen species contributing to homeostatic regulation and the pathogenesis of various cardiovascular diseases, including atherosclerosis, hypertension, endothelial dysfunction, and cardiac hypertrophy, is well established. The ability of oxidant species to mediate such effects is in part dependent on their ability to induce specific modifications on particular amino acids, which alter protein function leading to changes in cell signaling and function. The thiol containing amino acids, methionine and cysteine, are the only oxidized amino acids that undergo reduction by cellular enzymes and are, therefore, prime candidates in regulating physiological signaling. Various reports illustrate the significance of reversible oxidative modifications on cysteine thiols and their importance in modulating cardiovascular function and physiology. Recent Advances: The use of mass spectrometry, novel labeling techniques, and live cell imaging illustrate the emerging importance of reversible thiol modifications in cellular redox signaling and have advanced our analytical abilities. Critical Issues: Distinguishing redox signaling from oxidative stress remains unclear. S-nitrosylation as a precursor of S-glutathionylation is controversial and needs further clarification. Subcellular distribution of glutathione (GSH) may play an important role in local regulation, and targeted tools need to be developed. Furthermore, cellular redundancies of thiol metabolism complicate analysis and interpretation. Future Directions: The development of novel pharmacological analogs that specifically target subcellular compartments of GSH to promote or prevent local protein S-glutathionylation as well as the establishment of conditional gene ablation and transgenic animal models are needed. Antioxid. Redox Signal. 16, 524–542. PMID:22010840

Cystatin F Affects Natural Killer Cell Cytotoxicity

PubMed Central

Perišić Nanut, Milica; Sabotič, Jerica; Švajger, Urban; Jewett, Anahid; Kos, Janko

2017-01-01

Cystatin F is a cysteine peptidase inhibitor which, unlike other cystatin family members, is targeted to endosomal/lysosomal compartments. It is synthesized as an inactive disulfide-linked dimer which is then converted to an active monomer by proteolytic cleavage of 15 N-terminal residues. Cystatin F has been suggested to regulate the cytotoxicity of natural killer (NK) cells by inhibiting the major granzyme convertases, cathepsins C and H. To test this hypothesis, we prepared variants of cystatin F and analyzed their uptake, subcellular trafficking, and peptidase inhibition, as well as their impact on the cytotoxicity of NK-92 cells and primary NK cells. The N-glycosylation pattern is responsible for the secretion, uptake, and subcellular sorting of cystatin F in HeLa and Hek293 cells, whereas the legumain binding site had no effect on these processes. Active, N-terminally truncated, monomeric cystatin F can also be internalized by recipient cells and targeted to endo/lysosomes, affecting also cells lacking the activating peptidase. Cystatin F mutants capable of cell internalization and trafficking through the endo/lysosomal pathway significantly decreased cathepsin C and H activities, both in situ, following transfection and in trans, using conditioned media. Further, incubation of IL-2 stimulated NK-92 and primary NK cells with full-length and N-terminally truncated cystatin F mutants led to suppression of their granule-mediated cytotoxicity. This effect was most significant with the N-terminally truncated mutants. These results suggest that cystatin F can be an important mediator within tumor microenvironment affecting the cytotoxicity of NK cells and consequently antitumor immune response. PMID:29180998

Matrix metalloproteinase-2 and -9 in the cerebellum of teleost fish: Functional implications for adult neurogenesis.

PubMed

Sîrbulescu, Ruxandra F; Ilieş, Iulian; Zupanc, Günther K H

2015-09-01

Matrix metalloproteinases (MMPs) are a family of highly conserved zinc-dependent proteases involved in both development and pathogenesis. The present study examines the role of MMP-2 (gelatinase A) and MMP-9 (gelatinase B) in adult neurogenesis, using the corpus cerebelli, a subdivision of the cerebellum, of knifefish (Apteronotus leptorhynchus) as a model system. Transcripts of five isoforms of these gelatinases were identified in the central nervous system of this species. Sequence similarity analysis and homology modeling indicated that functionally and structurally critical elements were highly conserved in knifefish gelatinases. Immunohistochemical staining revealed a differential distribution of MMP-2 and MMP-9 at both the cellular and subcellular level. MMP-2 expression was found mainly in Sox2-immunopositive stem/progenitor cells, both quiescent and mitotically active; and was localized in both the cytoplasmic compartment and the nucleus. By contrast, MMP-9 immunoreactivity was absent in neurogenic niches and displayed a more homogenous distribution, with low to moderate intensity levels, in the molecular and granular layers. MMP-9 expression appeared to be restricted to the extracellular space. In situ zymography indicated that gelatinase activity matched the cellular and subcellular distributions of the two MMPs. The observed patterns of gelatinase activity and expression support the hypothesis that MMP-2 is primarily involved in regulation of the activity of stem/progenitor cells that give rise to new granule neurons, whereas MMP-9 facilitates migration of the progeny of these cells by proteolysis of extracellular matrix proteins. Copyright © 2015 Elsevier Inc. All rights reserved.

An Extended Proteome Map of the Lysosomal Membrane Reveals Novel Potential Transporters*

PubMed Central

Chapel, Agnès; Kieffer-Jaquinod, Sylvie; Sagné, Corinne; Verdon, Quentin; Ivaldi, Corinne; Mellal, Mourad; Thirion, Jaqueline; Jadot, Michel; Bruley, Christophe; Garin, Jérôme; Gasnier, Bruno; Journet, Agnès

2013-01-01

Lysosomes are membrane-bound endocytic organelles that play a major role in degrading cell macromolecules and recycling their building blocks. A comprehensive knowledge of the lysosome function requires an extensive description of its content, an issue partially addressed by previous proteomic analyses. However, the proteins underlying many lysosomal membrane functions, including numerous membrane transporters, remain unidentified. We performed a comparative, semi-quantitative proteomic analysis of rat liver lysosome-enriched and lysosome-nonenriched membranes and used spectral counts to evaluate the relative abundance of proteins. Among a total of 2,385 identified proteins, 734 proteins were significantly enriched in the lysosomal fraction, including 207 proteins already known or predicted as endo-lysosomal and 94 proteins without any known or predicted subcellular localization. The remaining 433 proteins had been previously assigned to other subcellular compartments but may in fact reside on lysosomes either predominantly or as a secondary location. Many membrane-associated complexes implicated in diverse processes such as degradation, membrane trafficking, lysosome biogenesis, lysosome acidification, signaling, and nutrient sensing were enriched in the lysosomal fraction. They were identified to an unprecedented extent as most, if not all, of their subunits were found and retained by our screen. Numerous transporters were also identified, including 46 novel potentially lysosomal proteins. We expressed 12 candidates in HeLa cells and observed that most of them colocalized with the lysosomal marker LAMP1, thus confirming their lysosomal residency. This list of candidate lysosomal proteins substantially increases our knowledge of the lysosomal membrane and provides a basis for further characterization of lysosomal functions. PMID:23436907

Electron microscopy observations on testis and spermatozoa of Leptodactylus chaquensis (Anura, Leptodactylidae).

PubMed

Iruzubieta Villagra, Lucrecia; Ramos, Inés; Cisint, Susana; Crespo, Claudia A; Fernández, Silvia N

2018-02-01

Scanning and transmission electron microscopy were used to investigate the fine structure of the testis and spermatozoa of toad Leptodactylus chaquensis. Our observations indicate that germinal compartment contains Sertoli (SC) and germ cells. The tight junctions and desmosomes among SC indicate the existence of an hematotesticular barrier in charge of maintaining the differences in the composition of the germinal and interstitial compartments. During spermatogenesis, SC acts as a structural support for germ cells. Secondary spermatogonias, spermatocytes and spermatids are joined by cytoplasmic bridges that allow communication between cells in the same cyst. Spermatids at the subcellular level two well-defined morphological stages can be observed: primary spermatids are rounded cells with an acrosomal vesicle attached to the nucleus which has a diameter of about 4.39±0.36μm. Secondary spermatids are elongated with a nucleus of about 19.50±0.92μm in diameter and the acrosome and the axoneme are located in opposite poles of the cells. At the apical end of the spermatozoon we can observe a large arrowhead-shaped acrosome (6.26±0.28μm in length) that takes up about one third of the gamete head with 17.33±0.29μm in length. The proximal centriole is located in the nuclear fossa while the distal centriole gives rise to the flagellar axoneme. The flagellum exhibits a typical pattern of "9+2" and adjacent to it is the axial fiber, and an undulating membrane stretches between both structures. Transmission electron microscopy observations allowed us to produce a diagram of the structure of the spermatozoon of L. chaquensis. Leydig cells, located in the interstitial compartment, show scarce cytoplasm, mitochondria and large-sized lipid droplets which would provide the raw matter for the synthesis of steroid hormones. Copyright © 2017 Elsevier Ltd. All rights reserved.

PC5-A-mediated processing of pro-neurotensin in early compartments of the regulated secretory pathway of PC5-transfected PC12 cells.

PubMed

Barbero, P; Rovère, C; De Bie, I; Seidah, N; Beaudet, A; Kitabgi, P

1998-09-25

Among the members of the proprotein convertase (PC) family, PC1 and PC2 have well established roles as prohormone convertases. Another good candidate for this role is PC5-A that has been shown to be present in the regulated secretory pathway of certain neuroendocrine tissues, but evidence that it can process prohormones is lacking. To determine whether PC5-A could function as a prohormone convertase and to compare its cleavage specificity with that of PC1 and PC2, we stably transfected the rat pheochromocytoma PC12 cell line with PC5-A and analyzed the biosynthesis and subcellular localization of the enzyme, as well as its ability to process pro-neurotensin/neuromedin N (pro-NT/NN) into active peptides. Our data showed that in transfected PC12 cells, PC5-A was converted from its 126-kDa precursor form into a 117-kDa mature form and, to a lesser extent, into a C-terminally truncated 65-kDa form of the 117-kDa product. Metabolic and immunochemical studies showed that PC5-A was sorted to early compartments of the regulated secretory pathway where it colocalized with immunoreactive NT. Furthermore, pro-NT/NN was processed in these compartments according to a pattern that differed from that previously described in PC1- and PC2-transfected PC12 cells. This pattern resembled that previously reported for pro-NT/NN processing in the adrenal medulla, a tissue known to express high levels of PC5-A. Altogether, these data demonstrate for the first time the ability of PC5-A to function as a prohormone convertase in the regulated secretory pathway and suggest a role for this enzyme in the physiological processing of pro-NT/NN.

Dressing up Nanoparticles: A Membrane Wrap to Induce Formation of the Virological Synapse

PubMed Central

Yu, Xinwei; Xu, Fangda; Ramirez, Nora-Guadalupe P.; Kijewski, Suzanne D. G.; Akiyama, Hisashi; Gummuluru, Suryaram; Reinhard, Björn M.

2015-01-01

Next generation nanoparticle-based drug delivery systems require the ability to target specific organelles or subcellular regions in selected target cells. Human immunodeficiency virus type I (HIV-1) particles are evolutionarily optimized nanocarriers that have evolved to avoid intracellular degradation and achieve enrichment at the synapse between mature dendritic cells (mDCs) and T cells by subverting cellular trafficking mechanisms. This study demonstrates that integration of the glycosphingolipid, GM3, in a membrane around a solid nanoparticle (NP) core is sufficient to recapitulate key aspects of the virus particle trafficking in mDCs. GM3 presenting artificial virus NPs (GM3-AVNs) accumulate in CD169+, CD81+, non-lysosomal compartments in an actin-dependent process that mimics the sequestration of HIV-1. Live-cell optical tracking studies reveal a preferential recruitment and arrest of surface scanning CD4+ T cells in direct vicinity to the AVN-enriched compartments. The formed mDC-T cell conjugates exhibit strong morphological similarities between the GM3-AVN-containing mDC-T cell synapse and the HIV-1 virological synapse, indicating that GM3-CD169 interactions alone are sufficient for establishing the mDC-T cell virological synapse. These results emphasize the potential of the GM3-AVN approach for providing therapeutic access to a key step of the host immune response – formation of the synaptic junction between an antigen-presenting cell (mDC) and T cells – for modulating and controlling immune responses. PMID:25853367

Intracellular Trafficking of Silicon Particles and Logic-Embedded Vectors

PubMed Central

Ferrati, Silvia; Mack, Aaron; Chiappini, Ciro; Liu, Xuewu; Bean, Andrew J.; Ferrari, Mauro; Serda, Rita E.

2010-01-01

Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon particles to be optimized for specific applications such as vascular targeting and avoidance of biological barriers commonly found between the site of drug injection and the final destination. In this study, the intracellular trafficking of unloaded carrier silicon particles and carrier particles loaded with secondary iron oxide nanoparticles was investigated. Following cellular uptake, membrane-encapsulated silicon particles migrated to the perinuclear region of the cell by a microtubule-driven mechanism. Surface charge, shape (spherical and hemispherical) and size (1.6 and 3.2 μm) of the particle did not alter the rate of migration. Maturation of the phagosome was associated with an increase in acidity and acquisition of markers of late endosomes and lysosomes. Cellular uptake of iron oxide nanoparticle-loaded silicon particles resulted in sorting of the particles and trafficking to unique destinations. The silicon carriers remained localized in phagosomes, while the second stage iron oxide nanoparticles were sorted into multi-vesicular bodies that dissociated from the phagosome into novel membrane-bound compartments. Release of iron from the cells may represent exocytosis of iron oxide nanoparticle-loaded vesicles. These results reinforce the concept of multi-functional nanocarriers, in which different particles are able to perform specific tasks, in order to deliver single- or multi-component payloads to specific sub-cellular compartments. PMID:20820744

Singlet oxygen signatures are detected independent of light or chloroplasts in response to multiple stresses.

PubMed

Mor, Avishai; Koh, Eugene; Weiner, Lev; Rosenwasser, Shilo; Sibony-Benyamini, Hadas; Fluhr, Robert

2014-05-01

The production of singlet oxygen is typically associated with inefficient dissipation of photosynthetic energy or can arise from light reactions as a result of accumulation of chlorophyll precursors as observed in fluorescent (flu)-like mutants. Such photodynamic production of singlet oxygen is thought to be involved in stress signaling and programmed cell death. Here we show that transcriptomes of multiple stresses, whether from light or dark treatments, were correlated with the transcriptome of the flu mutant. A core gene set of 118 genes, common to singlet oxygen, biotic and abiotic stresses was defined and confirmed to be activated photodynamically by the photosensitizer Rose Bengal. In addition, induction of the core gene set by abiotic and biotic selected stresses was shown to occur in the dark and in nonphotosynthetic tissue. Furthermore, when subjected to various biotic and abiotic stresses in the dark, the singlet oxygen-specific probe Singlet Oxygen Sensor Green detected rapid production of singlet oxygen in the Arabidopsis (Arabidopsis thaliana) root. Subcellular localization of Singlet Oxygen Sensor Green fluorescence showed its accumulation in mitochondria, peroxisomes, and the nucleus, suggesting several compartments as the possible origins or targets for singlet oxygen. Collectively, the results show that singlet oxygen can be produced by multiple stress pathways and can emanate from compartments other than the chloroplast in a light-independent manner. The results imply that the role of singlet oxygen in plant stress regulation and response is more ubiquitous than previously thought.

Singlet Oxygen Signatures Are Detected Independent of Light or Chloroplasts in Response to Multiple Stresses1[C][W

PubMed Central

Mor, Avishai; Koh, Eugene; Weiner, Lev; Rosenwasser, Shilo; Sibony-Benyamini, Hadas; Fluhr, Robert

2014-01-01

The production of singlet oxygen is typically associated with inefficient dissipation of photosynthetic energy or can arise from light reactions as a result of accumulation of chlorophyll precursors as observed in fluorescent (flu)-like mutants. Such photodynamic production of singlet oxygen is thought to be involved in stress signaling and programmed cell death. Here we show that transcriptomes of multiple stresses, whether from light or dark treatments, were correlated with the transcriptome of the flu mutant. A core gene set of 118 genes, common to singlet oxygen, biotic and abiotic stresses was defined and confirmed to be activated photodynamically by the photosensitizer Rose Bengal. In addition, induction of the core gene set by abiotic and biotic selected stresses was shown to occur in the dark and in nonphotosynthetic tissue. Furthermore, when subjected to various biotic and abiotic stresses in the dark, the singlet oxygen-specific probe Singlet Oxygen Sensor Green detected rapid production of singlet oxygen in the Arabidopsis (Arabidopsis thaliana) root. Subcellular localization of Singlet Oxygen Sensor Green fluorescence showed its accumulation in mitochondria, peroxisomes, and the nucleus, suggesting several compartments as the possible origins or targets for singlet oxygen. Collectively, the results show that singlet oxygen can be produced by multiple stress pathways and can emanate from compartments other than the chloroplast in a light-independent manner. The results imply that the role of singlet oxygen in plant stress regulation and response is more ubiquitous than previously thought. PMID:24599491

The signal transducer NPH3 integrates the phototropin1 photosensor with PIN2-based polar auxin transport in Arabidopsis root phototropism.

PubMed

Wan, Yinglang; Jasik, Jan; Wang, Li; Hao, Huaiqing; Volkmann, Dieter; Menzel, Diedrik; Mancuso, Stefano; Baluška, František; Lin, Jinxing

2012-02-01

Under blue light (BL) illumination, Arabidopsis thaliana roots grow away from the light source, showing a negative phototropic response. However, the mechanism of root phototropism is still unclear. Using a noninvasive microelectrode system, we showed that the BL sensor phototropin1 (phot1), the signal transducer NONPHOTOTROPIC HYPOCOTYL3 (NPH3), and the auxin efflux transporter PIN2 were essential for BL-induced auxin flux in the root apex transition zone. We also found that PIN2-green fluorescent protein (GFP) localized to vacuole-like compartments (VLCs) in dark-grown root epidermal and cortical cells, and phot1/NPH3 mediated a BL-initiated pathway that caused PIN2 redistribution to the plasma membrane. When dark-grown roots were exposed to brefeldin A (BFA), PIN2-GFP remained in VLCs in darkness, and BL caused PIN2-GFP disappearance from VLCs and induced PIN2-GFP-FM4-64 colocalization within enlarged compartments. In the nph3 mutant, both dark and BL BFA treatments caused the disappearance of PIN2-GFP from VLCs. However, in the phot1 mutant, PIN2-GFP remained within VLCs under both dark and BL BFA treatments, suggesting that phot1 and NPH3 play different roles in PIN2 localization. In conclusion, BL-induced root phototropism is based on the phot1/NPH3 signaling pathway, which stimulates the shootward auxin flux by modifying the subcellular targeting of PIN2 in the root apex transition zone.

Compartment-specific transcriptomics in a reef-building coral exposed to elevated temperatures

PubMed Central

Mayfield, Anderson B; Wang, Yu-Bin; Chen, Chii-Shiarng; Lin, Chung-Yen; Chen, Shu-Hwa

2014-01-01

Although rising ocean temperatures threaten scleractinian corals and the reefs they construct, certain reef corals can acclimate to elevated temperatures to which they are rarely exposed in situ. Specimens of the model Indo-Pacific reef coral Pocillopora damicornis collected from upwelling reefs of Southern Taiwan were previously found to have survived a 36-week exposure to 30°C, a temperature they encounter infrequently and one that can elicit the breakdown of the coral–dinoflagellate (genus Symbiodinium) endosymbiosis in many corals of the Pacific Ocean. To gain insight into the subcellular pathways utilized by both the coral hosts and their mutualistic Symbiodinium populations to acclimate to this temperature, mRNAs from both control (27°C) and high (30°C)-temperature samples were sequenced on an Illumina platform and assembled into a 236 435-contig transcriptome. These P. damicornis specimens were found to be ∼60% anthozoan and 40% microbe (Symbiodinium, other eukaryotic microbes, and bacteria), from an mRNA-perspective. Furthermore, a significantly higher proportion of genes from the Symbiodinium compartment were differentially expressed after two weeks of exposure. Specifically, at elevated temperatures, Symbiodinium populations residing within the coral gastrodermal tissues were more likely to up-regulate the expression of genes encoding proteins involved in metabolism than their coral hosts. Collectively, these transcriptome-scale data suggest that the two members of this endosymbiosis have distinct strategies for acclimating to elevated temperatures that are expected to characterize many of Earth's coral reefs in the coming decades. PMID:25354956

Microdosimetric study for nanosecond pulsed electric fields on a cell circuit model with nucleus.

PubMed

Denzi, Agnese; Merla, Caterina; Camilleri, Paola; Paffi, Alessandra; d'Inzeo, Guglielmo; Apollonio, Francesca; Liberti, Micaela

2013-10-01

Recently, scientific interest in electric pulses, always more intense and shorter and able to induce biological effects on both plasma and nuclear membranes, has greatly increased. Hence, microdosimetric models that include internal organelles like the nucleus have assumed increasing importance. In this work, a circuit model of the cell including the nucleus is proposed, which accounts for the dielectric dispersion of all cell compartments. The setup of the dielectric model of the nucleus is of fundamental importance in determining the transmembrane potential (TMP) induced on the nuclear membrane; here, this is demonstrated by comparing results for three different sets of nuclear dielectric properties present in the literature. The results have been compared, even including or disregarding the dielectric dispersion of the nucleus. The main differences have been found when using pulses shorter than 10 ns. This is due to the fact that the high spectral components of the shortest pulses are differently taken into account by the nuclear membrane transfer functions computed with and without nuclear dielectric dispersion. The shortest pulses are also the most effective in porating the intracellular structures, as confirmed by the time courses of the TMP calculated across the plasma and nuclear membranes. We show how dispersive nucleus models are unavoidable when dealing with pulses shorter than 10 ns because of the large spectral contents arriving above 100 MHz, i.e., over the typical relaxation frequencies of the dipolar mechanism of the molecules constituting the nuclear membrane and the subcellular cell compartments.

Disturbed neuronal ER-Golgi sorting of unassembled glycine receptors suggests altered subcellular processing is a cause of human hyperekplexia.

PubMed

Schaefer, Natascha; Kluck, Christoph J; Price, Kerry L; Meiselbach, Heike; Vornberger, Nadine; Schwarzinger, Stephan; Hartmann, Stephanie; Langlhofer, Georg; Schulz, Solveig; Schlegel, Nadja; Brockmann, Knut; Lynch, Bryan; Becker, Cord-Michael; Lummis, Sarah C R; Villmann, Carmen

2015-01-07

Recent studies on the pathogenic mechanisms of recessive hyperekplexia indicate disturbances in glycine receptor (GlyR) α1 biogenesis. Here, we examine the properties of a range of novel glycine receptor mutants identified in human hyperekplexia patients using expression in transfected cell lines and primary neurons. All of the novel mutants localized in the large extracellular domain of the GlyR α1 have reduced cell surface expression with a high proportion of receptors being retained in the ER, although there is forward trafficking of glycosylated subpopulations into the ER-Golgi intermediate compartment and cis-Golgi compartment. CD spectroscopy revealed that the mutant receptors have proportions of secondary structural elements similar to wild-type receptors. Two mutants in loop B (G160R, T162M) were functional, but none of those in loop D/β2-3 were. One nonfunctional truncated mutant (R316X) could be rescued by coexpression with the lacking C-terminal domain. We conclude that a proportion of GlyR α1 mutants can be transported to the plasma membrane but do not necessarily form functional ion channels. We suggest that loop D/β2-3 is an important determinant for GlyR trafficking and functionality, whereas alterations to loop B alter agonist potencies, indicating that residues here are critical elements in ligand binding. Copyright © 2015 the authors 0270-6474/15/350422-16$15.00/0.

Coordinated Endothelial Nitric Oxide Synthase activation by translocation and phosphorylation determines flow-induced NO production in resistance vessels

PubMed Central

Figueroa, Xavier F.; González, Daniel R.; Puebla, Mariela; Acevedo, Juan P.; Rojas-Libano, Daniel; Durán, Walter N.; Boric, Mauricio P.

2013-01-01

Background/Aims Endothelial nitric oxide synthase (eNOS) is associated with caveolin-1 (Cav-1) in plasma membrane. We tested the hypothesis that eNOS activation by shear stress in resistance vessels depends on synchronized phosphorylation, dissociation from Cav-1 and translocation of the membrane-bound enzyme to Golgi and cytosol. Methods In isolated, perfused rat arterial mesenteric beds, we evaluated the effect of changes in flow rate (2–10 mL/min), on NO production, eNOS phosphorylation at serine 1177, eNOS subcellular distribution and co-immunoprecipitation with Cav-1, in the presence or absence of extracellular Ca2+. Results Increases in flow induced a biphasic rise in NO production: a rapid transient phase (3–5-min) that peaked during the first 15-sec, followed by a sustained phase, which lasted until the end of stimulation. Concomitantly, flow caused a rapid translocation of eNOS from the microsomal compartment to the cytosol and Golgi, paralleled by an increase in eNOS phosphorylation and a reduction in eNOS-Cav-1 association. Transient NO production, eNOS translocation, and dissociation from Cav-1 depended on extracellular Ca2+, while sustained NO production was abolished by the PI3K-Akt blocker wortmannin. Conclusions In intact resistance vessels, changes in flow induce NO production by transient Ca2+-dependent eNOS translocation from membrane to intracellular compartments and sustained Ca2+-independent PI3K-Akt-mediated phosphorylation. PMID:24217770

Cathepsin B Activity Initiates Apoptosis via Digestive Protease Activation in Pancreatic Acinar Cells and Experimental Pancreatitis*

PubMed Central

Sendler, Matthias; Maertin, Sandrina; John, Daniel; Persike, Maria; Weiss, F. Ulrich; Krüger, Burkhard; Wartmann, Thomas; Wagh, Preshit; Halangk, Walter; Schaschke, Norbert; Mayerle, Julia; Lerch, Markus M.

2016-01-01

Pancreatitis is associated with premature activation of digestive proteases in the pancreas. The lysosomal hydrolase cathepsin B (CTSB) is a known activator of trypsinogen, and its deletion reduces disease severity in experimental pancreatitis. Here we studied the activation mechanism and subcellular compartment in which CTSB regulates protease activation and cellular injury. Cholecystokinin (CCK) increased the activity of CTSB, cathepsin L, trypsin, chymotrypsin, and caspase 3 in vivo and in vitro and induced redistribution of CTSB to a secretory vesicle-enriched fraction. Neither CTSB protein nor activity redistributed to the cytosol, where the CTSB inhibitors cystatin-B/C were abundantly present. Deletion of CTSB reduced and deletion of cathepsin L increased intracellular trypsin activation. CTSB deletion also abolished CCK-induced caspase 3 activation, apoptosis-inducing factor, as well as X-linked inhibitor of apoptosis protein degradation, but these depended on trypsinogen activation via CTSB. Raising the vesicular pH, but not trypsin inhibition, reduced CTSB activity. Trypsin inhibition did not affect apoptosis in hepatocytes. Deletion of CTSB affected apoptotic but not necrotic acinar cell death. In summary, CTSB in pancreatitis undergoes activation in a secretory, vesicular, and acidic compartment where it activates trypsinogen. Its deletion or inhibition regulates acinar cell apoptosis but not necrosis in two models of pancreatitis. Caspase 3-mediated apoptosis depends on intravesicular trypsinogen activation induced by CTSB, not CTSB activity directly, and this mechanism is pancreas-specific. PMID:27226576

Cathepsin B Activity Initiates Apoptosis via Digestive Protease Activation in Pancreatic Acinar Cells and Experimental Pancreatitis.

PubMed

Sendler, Matthias; Maertin, Sandrina; John, Daniel; Persike, Maria; Weiss, F Ulrich; Krüger, Burkhard; Wartmann, Thomas; Wagh, Preshit; Halangk, Walter; Schaschke, Norbert; Mayerle, Julia; Lerch, Markus M

2016-07-08

Pancreatitis is associated with premature activation of digestive proteases in the pancreas. The lysosomal hydrolase cathepsin B (CTSB) is a known activator of trypsinogen, and its deletion reduces disease severity in experimental pancreatitis. Here we studied the activation mechanism and subcellular compartment in which CTSB regulates protease activation and cellular injury. Cholecystokinin (CCK) increased the activity of CTSB, cathepsin L, trypsin, chymotrypsin, and caspase 3 in vivo and in vitro and induced redistribution of CTSB to a secretory vesicle-enriched fraction. Neither CTSB protein nor activity redistributed to the cytosol, where the CTSB inhibitors cystatin-B/C were abundantly present. Deletion of CTSB reduced and deletion of cathepsin L increased intracellular trypsin activation. CTSB deletion also abolished CCK-induced caspase 3 activation, apoptosis-inducing factor, as well as X-linked inhibitor of apoptosis protein degradation, but these depended on trypsinogen activation via CTSB. Raising the vesicular pH, but not trypsin inhibition, reduced CTSB activity. Trypsin inhibition did not affect apoptosis in hepatocytes. Deletion of CTSB affected apoptotic but not necrotic acinar cell death. In summary, CTSB in pancreatitis undergoes activation in a secretory, vesicular, and acidic compartment where it activates trypsinogen. Its deletion or inhibition regulates acinar cell apoptosis but not necrosis in two models of pancreatitis. Caspase 3-mediated apoptosis depends on intravesicular trypsinogen activation induced by CTSB, not CTSB activity directly, and this mechanism is pancreas-specific. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Steric exclusion and protein conformation determine the localization of plasma membrane transporters.

PubMed

Bianchi, Frans; Syga, Łukasz; Moiset, Gemma; Spakman, Dian; Schavemaker, Paul E; Punter, Christiaan M; Seinen, Anne-Bart; van Oijen, Antoine M; Robinson, Andrew; Poolman, Bert

2018-02-05

The plasma membrane (PM) of Saccharomyces cerevisiae contains membrane compartments, MCC/eisosomes and MCPs, named after the protein residents Can1 and Pma1, respectively. Using high-resolution fluorescence microscopy techniques we show that Can1 and the homologous transporter Lyp1 are able to diffuse into the MCC/eisosomes, where a limited number of proteins are conditionally trapped at the (outer) edge of the compartment. Upon addition of substrate, the immobilized proteins diffuse away from the MCC/eisosomes, presumably after taking a different conformation in the substrate-bound state. Our data indicate that the mobile fraction of all integral plasma membrane proteins tested shows extremely slow Brownian diffusion through most of the PM. We also show that proteins with large cytoplasmic domains, such as Pma1 and synthetic chimera of Can1 and Lyp1, are excluded from the MCC/eisosomes. We hypothesize that the distinct localization patterns found for these integral membrane proteins in S. cerevisiae arises from a combination of slow lateral diffusion, steric exclusion, and conditional trapping in membrane compartments.

Ischemic contracture of the foot and ankle: principles of management and prevention.

PubMed

Botte, M J; Santi, M D; Prestianni, C A; Abrams, R A

1996-03-01

A variety of clinical presentations can be encountered following compartment syndrome of the leg and foot. Deformity and functional impairment in the foot and ankle secondary to ischemia are determined by: 1) which leg compartments have been affected and to what degree extrinsic flexor or extensor "overpull" is exhibited, 2) degree of nerve injury sustained causing weakness or paralysis of extrinsic or intrinsic foot and ankle muscles, 3) which foot compartments have been affected and to what degree intrinsic "overpull" is exhibited, and 4) degree of sensory nerve injury leading to anesthesia, hypoesthesia, or hyperesthesia of the foot. Nonoperative therapy attempts to obtain or preserve joint mobility, increase strength, and provide corrective bracing and accommodative foot wear. Operative management is undertaken for treatment of residual nerve compression or refractory problematic deformities. Established surgical protocols are performed in a stepwise fashion, and include: 1) release of residual or secondary nerve compression; 2) release of fixed contractures, using infarct excision, myotendinous lengthening, muscle recession, or tenotomy; 3) tendon transfers or arthrodesis to increase function; and 4) osteotomy or amputation for severe, non-salvageable deformities.

Using Artificial Soil and Dry-Column Flash Chromatography to Simulate Organic Substance Leaching Process: A Colorful Environmental Chemistry Experiment

ERIC Educational Resources Information Center

de Avellar, Isa G. J.; Cotta, Tais A. P. G.; Neder, Amarilis de V. Finageiv

2012-01-01

Soil is an important and complex environmental compartment and soil contamination contributes to the pollution of aquifers and other water basins. A simple and low-cost experiment is described in which the mobility of three organic compounds in an artificial soil is examined using dry-column flash chromatography. The compounds were applied on top…

Alien species, agents of global change: ecology and management of the gypsy moth in North America as a case history

Treesearch

Andrew M. Liebhold

2003-01-01

Through out evolutionary history, water and land barriers served to isolate the world's biota into distinct compartments With the advent of greater human mobility and world trade, these barriers are breaking-down and alien species are increasingly being transported into new habitats. Many alien species have had devastating impacts on their environment resulting in...

A study of the dynamics of PTEN proteins in living cells using in vivo fluorescence correlation spectroscopy

NASA Astrophysics Data System (ADS)

Du, Zhixue; Dong, Chaoqing; Ren, Jicun

2017-06-01

PTEN (phosphatase and tensin homolog on chromosome 10) is one of the most important tumor-suppressor proteins, which plays a key role in negative regulation of the PI3K/AKT pathway, and governs many cellular processes including growth, proliferation, survival and migration. The dynamics of PTEN proteins in single living cells is as yet unclear owing to a shortage of suitable in vivo approaches. Here, we report a single-molecule method for in vivo study of the dynamics of PTEN proteins in living cells using fluorescence correlation spectroscopy (FCS). First, we established a monoclonal H1299 stable cell line expressing enhanced green fluorescent protein (EGFP) and PTEN (EGFP-PTEN) fusion proteins; we then developed an in vivo FCS method to study the dynamics of EGFP-PTEN both in the nucleus and the cytoplasm. We investigated the diffusion behaviors of EGFP and EGFP-PTEN in solution, nucleus and cytosol, and observed that the motion of PTEN in living cells was restricted compared with EGFP. Finally, we investigated the protein dynamics in living cells under oxidative stress stimulation and a cellular ATP depletion treatment. Under oxidative stress stimulation, the EGFP-PTEN concentration increased in the nucleus, but slightly decreased in the cytoplasm. The diffusion coefficient and alpha value of EGFP-PTEN reduced significantly both in the nucleus and cytoplasm; the significantly decreased alpha parameter indicates a more restricted Brownian diffusion behavior. Under the cellular ATP depletion treatment, the concentration of EGFP-PTEN remained unchanged in the nucleus and decreased significantly in cytosol. The diffusion coefficient of EGFP-PTEN decreased significantly in cytosol, but showed no significant change in the nucleus; the alpha value decreased significantly in both the nucleus and cytoplasm. These results suggest that the concentration and mobility of PTEN in the nucleus and cytoplasm can be regulated by stimulation methods. Our approach provides a unique method for real-time monitoring of protein dynamics in different subcellular compartments under different stimulation treatments.

Mobilization of steryl esters from lipid particles of the yeast Saccharomyces cerevisiae.

PubMed

Wagner, Andrea; Grillitsch, Karlheinz; Leitner, Erich; Daum, Günther

2009-02-01

In the yeast as in other eukaryotes, formation and hydrolysis of steryl esters (SE) are processes linked to lipid storage. In Saccharomyces cerevisiae, the three SE hydrolases Tgl1p, Yeh1p and Yeh2p contribute to SE mobilization from their site of storage, the lipid particles/droplets. Here, we provide evidence for enzymatic and cellular properties of these three hydrolytic enzymes. Using the respective single, double and triple deletion mutants and strains overexpressing the three enzymes, we demonstrate that each SE hydrolase exhibits certain substrate specificity. Interestingly, disturbance in SE mobilization also affects sterol biosynthesis in a type of feedback regulation. Sterol intermediates stored in SE and set free by SE hydrolases are recycled to the sterol biosynthetic pathway and converted to the final product, ergosterol. This recycling implies that the vast majority of sterol precursors are transported from lipid particles to the endoplasmic reticulum, where sterol biosynthesis is completed. Ergosterol formed through this route is then supplied to its subcellular destinations, especially the plasma membrane. Only a minor amount of sterol precursors are randomly distributed within the cell after cleavage from SE. Conclusively, SE storage and mobilization although being dispensable for yeast viability contribute markedly to sterol homeostasis and distribution.

Defining the Subcellular Interface of Nanoparticles by Live-Cell Imaging

PubMed Central

Hemmerich, Peter H.; von Mikecz, Anna H.

2013-01-01

Understanding of nanoparticle-bio-interactions within living cells requires knowledge about the dynamic behavior of nanomaterials during their cellular uptake, intracellular traffic and mutual reactions with cell organelles. Here, we introduce a protocol of combined kinetic imaging techniques that enables investigation of exemplary fluorochrome-labelled nanoparticles concerning their intracellular fate. By time-lapse confocal microscopy we observe fast, dynamin-dependent uptake of polystyrene and silica nanoparticles via the cell membrane within seconds. Fluorescence recovery after photobleaching (FRAP) experiments reveal fast and complete exchange of the investigated nanoparticles at mitochondria, cytoplasmic vesicles or the nuclear envelope. Nuclear translocation is observed within minutes by free diffusion and active transport. Fluorescence correlation spectroscopy (FCS) and raster image correlation spectroscopy (RICS) indicate diffusion coefficients of polystyrene and silica nanoparticles in the nucleus and the cytoplasm that are consistent with particle motion in living cells based on diffusion. Determination of the apparent hydrodynamic radii by FCS and RICS shows that nanoparticles exert their cytoplasmic and nuclear effects mainly as mobile, monodisperse entities. Thus, a complete toolkit of fluorescence fluctuation microscopy is presented for the investigation of nanomaterial biophysics in subcellular microenvironments that contributes to develop a framework of intracellular nanoparticle delivery routes. PMID:23637951

Drosophila Pelle phosphorylates Dichaete protein and influences its subcellular distribution in developing oocytes.

PubMed

Mutsuddi, Mousumi; Mukherjee, Ashim; Shen, Baohe; Manley, James L; Nambu, John R

2010-01-01

The Drosophila Dichaete gene encodes a member of the Sox family of high mobility group (HMG) domain proteins that have crucial gene regulatory functions in diverse developmental processes. The subcellular localization and transcriptional regulatory activities of Sox proteins can be regulated by several post-translational modifications. To identify genes that functionally interact with Dichaete, we undertook a genetic modifier screen based on a Dichaete gain-of-function phenotype in the adult eye. Mutations in several genes, including decapentaplegic, engrailed and pelle, behaved as dominant modifiers of this eye phenotype. Further analysis of pelle mutants revealed that loss of pelle function results in alterations in the distinctive cytoplasmic distribution of Dichaete protein within the developing oocyte, as well as defects in the elaboration of individual egg chambers. The death domain-containing region of the Pelle protein kinase was found to associate with both Dichaete and mouse Sox2 proteins, and Pelle can phosphorylate Dichaete protein in vitro. Overall, these findings reveal that maternal functions of pelle are essential for proper localization of Dichaete protein in the oocyte and normal egg chamber formation. Dichaete appears to be a novel phosphorylation substrate for Pelle and may function in a Pelle-dependent signaling pathway during oogenesis.

Cortical Interneuron Subtypes Vary in Their Axonal Action Potential Properties.

PubMed

Casale, Amanda E; Foust, Amanda J; Bal, Thierry; McCormick, David A

2015-11-25

The role of interneurons in cortical microcircuits is strongly influenced by their passive and active electrical properties. Although different types of interneurons exhibit unique electrophysiological properties recorded at the soma, it is not yet clear whether these differences are also manifested in other neuronal compartments. To address this question, we have used voltage-sensitive dye to image the propagation of action potentials into the fine collaterals of axons and dendrites in two of the largest cortical interneuron subtypes in the mouse: fast-spiking interneurons, which are typically basket or chandelier neurons; and somatostatin containing interneurons, which are typically regular spiking Martinotti cells. We found that fast-spiking and somatostatin-expressing interneurons differed in their electrophysiological characteristics along their entire dendrosomatoaxonal extent. The action potentials generated in the somata and axons, including axon collaterals, of somatostatin-expressing interneurons are significantly broader than those generated in the same compartments of fast-spiking inhibitory interneurons. In addition, action potentials back-propagated into the dendrites of somatostatin-expressing interneurons much more readily than fast-spiking interneurons. Pharmacological investigations suggested that axonal action potential repolarization in both cell types depends critically upon Kv1 channels, whereas the axonal and somatic action potentials of somatostatin-expressing interneurons also depend on BK Ca(2+)-activated K(+) channels. These results indicate that the two broad classes of interneurons studied here have expressly different subcellular physiological properties, allowing them to perform unique computational roles in cortical circuit operations. Neurons in the cerebral cortex are of two major types: excitatory and inhibitory. The proper balance of excitation and inhibition in the brain is critical for its operation. Neurons contain three main compartments: dendritic, somatic, and axonal. How the neurons receive information, process it, and pass on new information depends upon how these three compartments operate. While it has long been assumed that axons are simply for conducting information from the cell body to the synapses, here we demonstrate that the axons of different types of interneurons, the inhibitory cells, possess differing electrophysiological properties. This result implies that differing types of interneurons perform different tasks in the cortex, not only through their anatomical connections, but also through how their axons operate. Copyright © 2015 the authors 0270-6474/15/3515555-13$15.00/0.

A genome-wide resource for the analysis of protein localisation in Drosophila

PubMed Central

Sarov, Mihail; Barz, Christiane; Jambor, Helena; Hein, Marco Y; Schmied, Christopher; Suchold, Dana; Stender, Bettina; Janosch, Stephan; KJ, Vinay Vikas; Krishnan, RT; Krishnamoorthy, Aishwarya; Ferreira, Irene RS; Ejsmont, Radoslaw K; Finkl, Katja; Hasse, Susanne; Kämpfer, Philipp; Plewka, Nicole; Vinis, Elisabeth; Schloissnig, Siegfried; Knust, Elisabeth; Hartenstein, Volker; Mann, Matthias; Ramaswami, Mani; VijayRaghavan, K; Tomancak, Pavel; Schnorrer, Frank

2016-01-01

The Drosophila genome contains >13000 protein-coding genes, the majority of which remain poorly investigated. Important reasons include the lack of antibodies or reporter constructs to visualise these proteins. Here, we present a genome-wide fosmid library of 10000 GFP-tagged clones, comprising tagged genes and most of their regulatory information. For 880 tagged proteins, we created transgenic lines, and for a total of 207 lines, we assessed protein expression and localisation in ovaries, embryos, pupae or adults by stainings and live imaging approaches. Importantly, we visualised many proteins at endogenous expression levels and found a large fraction of them localising to subcellular compartments. By applying genetic complementation tests, we estimate that about two-thirds of the tagged proteins are functional. Moreover, these tagged proteins enable interaction proteomics from developing pupae and adult flies. Taken together, this resource will boost systematic analysis of protein expression and localisation in various cellular and developmental contexts. DOI: http://dx.doi.org/10.7554/eLife.12068.001 PMID:26896675

Intrinsically disordered proteins aggregate at fungal cell-to-cell channels and regulate intercellular connectivity

PubMed Central

Lai, Julian; Koh, Chuan Hock; Tjota, Monika; Pieuchot, Laurent; Raman, Vignesh; Chandrababu, Karthik Balakrishna; Yang, Daiwen; Wong, Limsoon; Jedd, Gregory

2012-01-01

Like animals and plants, multicellular fungi possess cell-to-cell channels (septal pores) that allow intercellular communication and transport. Here, using a combination of MS of Woronin body-associated proteins and a bioinformatics approach that identifies related proteins based on composition and character, we identify 17 septal pore-associated (SPA) proteins that localize to the septal pore in rings and pore-centered foci. SPA proteins are not homologous at the primary sequence level but share overall physical properties with intrinsically disordered proteins. Some SPA proteins form aggregates at the septal pore, and in vitro assembly assays suggest aggregation through a nonamyloidal mechanism involving mainly α-helical and disordered structures. SPA loss-of-function phenotypes include excessive septation, septal pore degeneration, and uncontrolled Woronin body activation. Together, our data identify the septal pore as a complex subcellular compartment and focal point for the assembly of unstructured proteins controlling diverse aspects of intercellular connectivity. PMID:22955885

Computer-based prediction of mitochondria-targeting peptides.

PubMed

Martelli, Pier Luigi; Savojardo, Castrense; Fariselli, Piero; Tasco, Gianluca; Casadio, Rita

2015-01-01

Computational methods are invaluable when protein sequences, directly derived from genomic data, need functional and structural annotation. Subcellular localization is a feature necessary for understanding the protein role and the compartment where the mature protein is active and very difficult to characterize experimentally. Mitochondrial proteins encoded on the cytosolic ribosomes carry specific patterns in the precursor sequence from where it is possible to recognize a peptide targeting the protein to its final destination. Here we discuss to which extent it is feasible to develop computational methods for detecting mitochondrial targeting peptides in the precursor sequences and benchmark our and other methods on the human mitochondrial proteins endowed with experimentally characterized targeting peptides. Furthermore, we illustrate our newly implemented web server and its usage on the whole human proteome in order to infer mitochondrial targeting peptides, their cleavage sites, and whether the targeting peptide regions contain or not arginine-rich recurrent motifs. By this, we add some other 2,800 human proteins to the 124 ones already experimentally annotated with a mitochondrial targeting peptide.

A Low Affinity GCaMP3 Variant (GCaMPer) for Imaging the Endoplasmic Reticulum Calcium Store.

PubMed

Henderson, Mark J; Baldwin, Heather A; Werley, Christopher A; Boccardo, Stefano; Whitaker, Leslie R; Yan, Xiaokang; Holt, Graham T; Schreiter, Eric R; Looger, Loren L; Cohen, Adam E; Kim, Douglas S; Harvey, Brandon K

2015-01-01

Endoplasmic reticulum calcium homeostasis is critical for cellular functions and is disrupted in diverse pathologies including neurodegeneration and cardiovascular disease. Owing to the high concentration of calcium within the ER, studying this subcellular compartment requires tools that are optimized for these conditions. To develop a single-fluorophore genetically encoded calcium indicator for this organelle, we targeted a low affinity variant of GCaMP3 to the ER lumen (GCaMPer (10.19)). A set of viral vectors was constructed to express GCaMPer in human neuroblastoma cells, rat primary cortical neurons, and human induced pluripotent stem cell-derived cardiomyocytes. We observed dynamic changes in GCaMPer (10.19) fluorescence in response to pharmacologic manipulations of the ER calcium store. Additionally, periodic calcium efflux from the ER was observed during spontaneous beating of cardiomyocytes. GCaMPer (10.19) has utility in imaging ER calcium in living cells and providing insight into luminal calcium dynamics under physiologic and pathologic states.

System and method for controlling depth of imaging in tissues using fluorescence microscopy under ultraviolet excitation following staining with fluorescing agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demos, Stavros; Levenson, Richard

The present disclosure relates to a method for analyzing tissue specimens. In one implementation the method involves obtaining a tissue sample and exposing the sample to one or more fluorophores as contrast agents to enhance contrast of subcellular compartments of the tissue sample. The tissue sample is illuminated by an ultraviolet (UV) light having a wavelength between about 200 nm to about 400 nm, with the wavelength being selected to result in penetration to only a specified depth below a surface of the tissue sample. Inter-image operations between images acquired under different imaging parameters allow for improvement of the imagemore » quality via removal of unwanted image components. A microscope may be used to image the tissue sample and provide the image to an image acquisition system that makes use of a camera. The image acquisition system may create a corresponding image that is transmitted to a display system for processing and display.« less

Cell-specific STORM superresolution imaging reveals nanoscale organization of cannabinoid signaling

PubMed Central

Szabó, Szilárd I.; Szabadits, Eszter; Pintér, Balázs; Woodhams, Stephen G.; Henstridge, Christopher M.; Balla, Gyula Y.; Nyilas, Rita; Varga, Csaba; Lee, Sang-Hun; Matolcsi, Máté; Cervenak, Judit; Kacskovics, Imre; Watanabe, Masahiko; Sagheddu, Claudia; Melis, Miriam; Pistis, Marco; Soltesz, Ivan; Katona, István

2014-01-01

A major challenge in neuroscience is to determine the nanoscale position and quantity of signaling molecules in a cell-type-, and subcellular compartment-specific manner. We therefore developed a novel approach combining cell-specific physiological and anatomical characterization with superresolution imaging, and studied the molecular and structural parameters shaping the physiological properties of synaptic endocannabinoid signaling in the mouse hippocampus. We found that axon terminals of perisomatically-projecting GABAergic interneurons possess increased CB1 receptor number, active-zone complexity, and receptor/effector ratio compared to dendritically-projecting interneurons, in agreement with higher efficiency of cannabinoid signaling at somatic versus dendritic synapses. Furthermore, chronic Δ9-tetrahydrocannabinol administration, which reduces cannabinoid efficacy on GABA release, evoked dramatic CB1-downregulation in a dose-dependent manner. Full receptor recovery required several weeks after cessation of Δ9-tetrahydrocannabinol treatment. These findings demonstrate that cell-type-specific nanoscale analysis of endogenous protein distribution is possible in brain circuits, and identify novel molecular properties controlling endocannabinoid signaling and cannabis-induced cognitive dysfunction. PMID:25485758

Pathogen trafficking pathways and host phosphoinositide metabolism.

PubMed

Weber, Stefan S; Ragaz, Curdin; Hilbi, Hubert

2009-03-01

Phosphoinositide (PI) glycerolipids are key regulators of eukaryotic signal transduction, cytoskeleton architecture and membrane dynamics. The host cell PI metabolism is targeted by intracellular bacterial pathogens, which evolved intricate strategies to modulate uptake processes and vesicle trafficking pathways. Upon entering eukaryotic host cells, pathogenic bacteria replicate in distinct vacuoles or in the host cytoplasm. Vacuolar pathogens manipulate PI levels to mimic or modify membranes of subcellular compartments and thereby establish their replicative niche. Legionella pneumophila, Brucella abortus, Mycobacterium tuberculosis and Salmonella enterica translocate effector proteins into the host cell, some of which anchor to the vacuolar membrane via PIs or enzymatically turnover PIs. Cytoplasmic pathogens target PI metabolism at the plasma membrane, thus modulating their uptake and antiapoptotic signalling pathways. Employing this strategy, Shigella flexneri directly injects a PI-modifying effector protein, while Listeria monocytogenes exploits PI metabolism indirectly by binding to transmembrane receptors. Thus, regardless of the intracellular lifestyle of the pathogen, PI metabolism is critically involved in the interactions with host cells.

Bioavailability of flavonoids: a review of their membrane transport and the function of bilitranslocase in animal and plant organisms.

PubMed

Passamonti, Sabina; Terdoslavich, Michela; Franca, Raffaella; Vanzo, Andreja; Tramer, Federica; Braidot, Enrico; Petrussa, Elisa; Vianello, Angelo

2009-05-01

Fruits and vegetables are rich in flavonoids, and ample epidemiological data show that diets rich in fruits and vegetables confer protection against cardiovascular, neurodegenerative and inflammatory diseases, and cancer. However, flavonoid bioavailability is reportedly very low in mammals and the molecular mechanisms of their action are still poorly known. This review focuses on membrane transport of flavonoids, a critical determinant of their bioavailability. Cellular influx and efflux transporters are reviewed for their involvement in the absorption of flavonoids from the gastro-intestinal tract and their subsequent tissue distribution. A focus on the mammalian bilirubin transporter bilitranslocase (TCDB 2.A.65.1.1) provides further insight into flavonoid bioavailability and its relationship with plasma bilirubin (an endogenous antioxidant). The general function of bilitranslocase as a flavonoid membrane transporter is further demonstrated by the occurrence of a plant homologue in organs (petals, berries) where flavonoid biosynthesis is most active. Bilitranslocase appears associated with sub-cellular membrane compartments and operates as a flavonoid membrane transporter.

Subcellular trace element distribution in Geosiphon pyriforme

NASA Astrophysics Data System (ADS)

Maetz, Mischa; Schüßler, Arthur; Wallianos, Alexandros; Traxel, Kurt

1999-04-01

Geosiphon pyriforme is a unique endosymbiotic consortium consisting of a soil dwelling fungus and the cyanobacterium Nostoc punctiforme. At present this symbiosis becomes very interesting because of its phylogenetic relationship to the arbuscular mycorrhizal (AM) fungi. Geosiphon pyriforme could be an important model system for these obligate symbiotic fungi, which supply 80-90% of all land plant species with nutrients, in particular phosphorous and trace elements. Combined PIXE and STIM analyses of the various compartments of Geosiphon give hints for the matter exchange between the symbiotic partners and their environment and the kind of nutrient storage and acquisition, in particular related to nitrogen fixation and metabolism. To determine the quality of our PIXE results we analysed several geological and biological standards over a time period of three years. This led to an overall precision of about 6% and an accuracy of 5-10% for nearly all detectable elements. In combination with the correction model for the occurring mass loss during the analyses this holds true even for biological targets.

Characterization and storage of malaria antigens: Fractionation of Plasmodium knowlesi-induced antigens of rhesus monkey erythrocyte membranes*

PubMed Central

Schmidt-Ullrich, R.; Wallach, D. F. H.; Lightholder, J.

1979-01-01

In order to characterize parasite-induced host cell membrane antigens, the plasma membranes of Plasmodium knowlesi-infected rhesus erythrocytes have been compared with those of normal red cells and purified schizonts by immunochemical and biochemical techniques. Host cell membranes and schizonts were separated by differential centrifugation following nitrogen decompression. Isolated schizonts were further fractionated into several subcellular compartments. Crossed-immune electrophoresis, against monkey anti-schizont serum, of Triton X-100-solubilized material identified 7 P. knowlesi-specific antigens, of which 4 could be detected only in the host cell membranes. These membranes also contained 3 proteins, with relative molecular masses of 55 000, 65 000 and 90 000 and isoelectric points at pH 4.5, 4.5 and 5.2, respectively, which are lacking in normal membranes. Pulse-chase experiments with (14C)-glucosamine showed that these parasite-induced host cell membrane components are glycoproteins. ImagesFig. 1Fig. 2 PMID:120762

A resilient formin-derived cortical actin meshwork in the rear drives actomyosin-based motility in 2D confinement

PubMed Central

Ramalingam, Nagendran; Franke, Christof; Jaschinski, Evelin; Winterhoff, Moritz; Lu, Yao; Brühmann, Stefan; Junemann, Alexander; Meier, Helena; Noegel, Angelika A.; Weber, Igor; Zhao, Hongxia; Merkel, Rudolf; Schleicher, Michael; Faix, Jan

2015-01-01

Cell migration is driven by the establishment of disparity between the cortical properties of the softer front and the more rigid rear allowing front extension and actomyosin-based rear contraction. However, how the cortical actin meshwork in the rear is generated remains elusive. Here we identify the mDia1-like formin A (ForA) from Dictyostelium discoideum that generates a subset of filaments as the basis of a resilient cortical actin sheath in the rear. Mechanical resistance of this actin compartment is accomplished by actin crosslinkers and IQGAP-related proteins, and is mandatory to withstand the increased contractile forces in response to mechanical stress by impeding unproductive blebbing in the rear, allowing efficient cell migration in two-dimensional-confined environments. Consistently, ForA supresses the formation of lateral protrusions, rapidly relocalizes to new prospective ends in repolarizing cells and is required for cortical integrity. Finally, we show that ForA utilizes the phosphoinositide gradients in polarized cells for subcellular targeting. PMID:26415699

Spectroscopic studies of anthracyclines: Structural characterization and in vitro tracking

NASA Astrophysics Data System (ADS)

Szafraniec, Ewelina; Majzner, Katarzyna; Farhane, Zeineb; Byrne, Hugh J.; Lukawska, Malgorzata; Oszczapowicz, Irena; Chlopicki, Stefan; Baranska, Malgorzata

2016-12-01

A broad spectroscopic characterization, using ultraviolet-visible (UV-vis) and Fourier transform infrared absorption as well as Raman scattering, of two commonly used anthracyclines antibiotics (DOX) daunorubicin (DNR), their epimers (EDOX, EDNR) and ten selected analogs is presented. The paper serves as a comprehensive spectral library of UV-vis, IR and Raman spectra of anthracyclines in the solid state and in solution. The particular advantage of Raman spectroscopy for the measurement and analysis of individual antibiotics is demonstrated. Raman spectroscopy can be used to monitor the in vitro uptake and distribution of the drug in cells, using both 488 nm and 785 nm as source wavelengths, with submicrometer spatial resolution, although the cellular accumulation of the drug is different in each case. The high information content of Raman spectra allows studies of the drug-cell interactions, and so the method seems very suitable for monitoring drug uptake and mechanisms of interaction with cellular compartments at the subcellular level.

Plastid, nuclear and reverse transcriptase sequences in the mitochondrial genome of Oenothera: is genetic information transferred between organelles via RNA?

PubMed Central

Schuster, W; Brennicke, A

1987-01-01

We describe an open reading frame (ORF) with high homology to reverse transcriptase in the mitochondrial genome of Oenothera. This ORF displays all the characteristics of an active plant mitochondrial gene with a possible ribosome binding site and 39% T in the third codon position. It is located between a sequence fragment from the plastid genome and one of nuclear origin downstream from the gene encoding subunit 5 of the NADH dehydrogenase. The nuclear derived sequence consists of 528 nucleotides from the small ribosomal RNA and contains an expansion segment unique to nuclear rRNAs. The plastid sequence contains part of the ribosomal protein S4 and the complete tRNA(Ser). The observation that only transcribed sequences have been found i more than one subcellular compartment in higher plants suggests that interorganellar transfer of genetic information may occur via RNA and subsequent local reverse transcription and genomic integration. PMID:14650433

Dual regulation of cytoplasmic and mitochondrial acetyl-CoA utilization for improved isoprene production in Saccharomyces cerevisiae.

PubMed

Lv, Xiaomei; Wang, Fan; Zhou, Pingping; Ye, Lidan; Xie, Wenping; Xu, Haoming; Yu, Hongwei

2016-09-21

Microbial production of isoprene from renewable feedstock is a promising alternative to traditional petroleum-based processes. Currently, efforts to improve isoprenoid production in Saccharomyces cerevisiae mainly focus on cytoplasmic engineering, whereas comprehensive engineering of multiple subcellular compartments is rarely reported. Here, we propose dual metabolic engineering of cytoplasmic and mitochondrial acetyl-CoA utilization to boost isoprene synthesis in S. cerevisiae. This strategy increases isoprene production by 2.1-fold and 1.6-fold relative to the recombinant strains with solely mitochondrial or cytoplasmic engineering, respectively. By combining a modified reiterative recombination system for rapid pathway assembly, a two-phase culture process for dynamic metabolic regulation, and aerobic fed-batch fermentation for sufficient supply of acetyl-coA and carbon, we achieve 2527, mg l(-1) of isoprene, which is the highest ever reported in engineered eukaryotes. We propose this strategy as an efficient approach to enhancing isoprene production in yeast, which might open new possibilities for bioproduction of other value-added chemicals.

FlpStop, a tool for conditional gene control in Drosophila

PubMed Central

Fisher, Yvette E; Yang, Helen H; Isaacman-Beck, Jesse; Xie, Marjorie; Gohl, Daryl M; Clandinin, Thomas R

2017-01-01

Manipulating gene function cell type-specifically is a common experimental goal in Drosophila research and has been central to studies of neural development, circuit computation, and behavior. However, current cell type-specific gene disruption techniques in flies often reduce gene activity incompletely or rely on cell division. Here we describe FlpStop, a generalizable tool for conditional gene disruption and rescue in post-mitotic cells. In proof-of-principle experiments, we manipulated apterous, a regulator of wing development. Next, we produced conditional null alleles of Glutamic acid decarboxylase 1 (Gad1) and Resistant to dieldrin (Rdl), genes vital for GABAergic neurotransmission, as well as cacophony (cac) and paralytic (para), voltage-gated ion channels central to neuronal excitability. To demonstrate the utility of this approach, we manipulated cac in a specific visual interneuron type and discovered differential regulation of calcium signals across subcellular compartments. Thus, FlpStop will facilitate investigations into the interactions between genes, circuits, and computation. DOI: http://dx.doi.org/10.7554/eLife.22279.001 PMID:28211790

Carbon nanotubes might improve neuronal performance by favouring electrical shortcuts.

PubMed

Cellot, Giada; Cilia, Emanuele; Cipollone, Sara; Rancic, Vladimir; Sucapane, Antonella; Giordani, Silvia; Gambazzi, Luca; Markram, Henry; Grandolfo, Micaela; Scaini, Denis; Gelain, Fabrizio; Casalis, Loredana; Prato, Maurizio; Giugliano, Michele; Ballerini, Laura

2009-02-01

Carbon nanotubes have been applied in several areas of nerve tissue engineering to probe and augment cell behaviour, to label and track subcellular components, and to study the growth and organization of neural networks. Recent reports show that nanotubes can sustain and promote neuronal electrical activity in networks of cultured cells, but the ways in which they affect cellular function are still poorly understood. Here, we show, using single-cell electrophysiology techniques, electron microscopy analysis and theoretical modelling, that nanotubes improve the responsiveness of neurons by forming tight contacts with the cell membranes that might favour electrical shortcuts between the proximal and distal compartments of the neuron. We propose the 'electrotonic hypothesis' to explain the physical interactions between the cell and nanotube, and the mechanisms of how carbon nanotubes might affect the collective electrical activity of cultured neuronal networks. These considerations offer a perspective that would allow us to predict or engineer interactions between neurons and carbon nanotubes.

Single-copy gene detection using branched DNA (bDNA) in situ hybridization.

PubMed

Player, A N; Shen, L P; Kenny, D; Antao, V P; Kolberg, J A

2001-05-01

We have developed a branched DNA in situ hybridization (bDNA ISH) method for detection of human papillomavirus (HPV) DNA in whole cells. Using human cervical cancer cell lines with known copies of HPV DNA, we show that the bDNA ISH method is highly sensitive, detecting as few as one or two copies of HPV DNA per cell. By modifying sample pretreatment, viral mRNA or DNA sequences can be detected using the same set of oligonucleotide probes. In experiments performed on mixed populations of cells, the bDNA ISH method is highly specific and can distinguish cells with HPV-16 from cells with HPV-18 DNA. Furthermore, we demonstrate that the bDNA ISH method provides precise localization, yielding positive signals retained within the subcellular compartments in which the target nucleic acid sequences are localized. As an effective and convenient means for nucleic acid detection, the bDNA ISH method is applicable to the detection of cancers and infectious agents. (J Histochem Cytochem 49:603-611, 2001)

Electron microscopy for ultrastructural analysis and protein localization in Saccharomyces cerevisiae

PubMed Central

Frankl, Andri; Mari, Muriel; Reggiori, Fulvio

2015-01-01

The yeast Saccharomyces cerevisiae is a key model system for studying of a multitude of cellular processes because of its amenability to genetics, molecular biology and biochemical procedures. Ultrastructural examinations of this organism, though, are traditionally difficult because of the presence of a thick cell wall and the high density of cytoplasmic proteins. A series of recent methodological and technical developments, however, has revived interest in morphological analyses of yeast (e.g. 123). Here we present a review of established and new methods, from sample preparation to imaging, for the ultrastructural analysis of S. cerevisiae. We include information for the use of different fixation methods, embedding procedures, approaches for contrast enhancement, and sample visualization techniques, with references to successful examples. The goal of this review is to guide researchers that want to investigate a particular process at the ultrastructural level in yeast by aiding in the selection of the most appropriate approach to visualize a specific structure or subcellular compartment. PMID:28357267

Moonlighting proteins in cancer.

PubMed

Min, Kyung-Won; Lee, Seong-Ho; Baek, Seung Joon

2016-01-01

Since the 1980s, growing evidence suggested that the cellular localization of proteins determined their activity and biological functions. In a classical view, a protein is characterized by the single cellular compartment where it primarily resides and functions. It is now believed that when proteins appear in different subcellular locations, the cells surpass the expected activity of proteins given the same genomic information to fulfill complex biological behavior. Many proteins are recognized for having the potential to exist in multiple locations in cells. Dysregulation of translocation may cause cancer or contribute to poorer cancer prognosis. Thus, quantitative and comprehensive assessment of dynamic proteins and associated protein movements could be a promising indicator in determining cancer prognosis and efficiency of cancer treatment and therapy. This review will summarize these so-called moonlighting proteins, in terms of a coupled intracellular cancer signaling pathway. Determination of the detailed biological intracellular and extracellular transit and regulatory activity of moonlighting proteins permits a better understanding of cancer and identification of potential means of molecular intervention. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

March separate, strike together--role of phosphorylated TAU in mitochondrial dysfunction in Alzheimer's disease.

PubMed

Eckert, Anne; Nisbet, Rebecca; Grimm, Amandine; Götz, Jürgen

2014-08-01

The energy demand and calcium buffering requirements of the brain are met by the high number of mitochondria in neurons and in these, especially at the synapses. Mitochondria are the major producer of reactive oxygen species (ROS); at the same time, they are damaged by ROS that are induced by abnormal protein aggregates that characterize human neurodegenerative diseases such as Alzheimer's disease (AD). Because synaptic mitochondria are long-lived, any damage exerted by these aggregates impacts severely on neuronal function. Here we review how increased TAU, a defining feature of AD and related tauopathies, impairs mitochondrial function by following the principle: 'March separate, strike together!' In the presence of amyloid-β, TAU's toxicity is augmented suggesting synergistic pathomechanisms. In order to restore mitochondrial functions in neurodegeneration as a means of therapeutic intervention it will be important to integrate the various aspects of dysfunction and get a handle on targeting distinct cell types and subcellular compartments. © 2013.

Quantitative Analysis of Protein Translocations by Microfluidic Total Internal Reflection Fluorescence Flow Cytometry

PubMed Central

Wang, Jun; Fei, Bei; Geahlen, Robert L.

2010-01-01

Protein translocation, or the change in a protein’s location between different subcellular compartments, is a critical process by which intracellular proteins carry out their cellular functions. Aberrant translocation events contribute to various diseases ranging from metabolic disorders to cancer. In this study, we demonstrate the use of a newly developed single-cell tool, microfluidic total internal reflection fluorescence flow cytometry (TIRF-FC), for detecting both cytosol to plasma membrane and cytosol to nucleus translocations using the tyrosine kinase Syk and the transcription factor NF-κB as models. This technique detects fluorescent molecules at the plasma membrane and in the membrane-proximal cytosol in single cells. We were able to record quantitatively changes in the fluorescence density in the evanescent field associated with these translocation processes for large cell populations with single cell resolution. We envision that TIRF-FC will provide a new approach to explore the molecular biology and clinical relevance of protein translocations. PMID:20820633

Cellular mechanisms responsible for cell-to-cell spreading of prions.

PubMed

Vilette, Didier; Courte, Josquin; Peyrin, Jean Michel; Coudert, Laurent; Schaeffer, Laurent; Andréoletti, Olivier; Leblanc, Pascal

2018-05-14

Prions are infectious agents that cause fatal neurodegenerative diseases. Current evidence indicates that they are essentially composed of an abnormally folded protein (PrP Sc ). These abnormal aggregated PrP Sc species multiply in infected cells by recruiting and converting the host PrP C protein into new PrP Sc . How prions move from cell to cell and progressively spread across the infected tissue is of crucial importance and may provide experimental opportunity to delay the progression of the disease. In infected cells, different mechanisms have been identified, including release of infectious extracellular vesicles and intercellular transfer of PrP Sc -containing organelles through tunneling nanotubes. These findings should allow manipulation of the intracellular trafficking events targeting PrP Sc in these particular subcellular compartments to experimentally address the relative contribution of these mechanisms to in vivo prion pathogenesis. In addition, such information may prompt further experimental strategies to decipher the causal roles of protein misfolding and aggregation in other human neurodegenerative diseases.

Vesicular trafficking of immune mediators in human eosinophils revealed by immunoelectron microscopy.

PubMed

Melo, Rossana C N; Weller, Peter F

2016-10-01

Electron microscopy (EM)-based techniques are mostly responsible for our current view of cell morphology at the subcellular level and continue to play an essential role in biological research. In cells from the immune system, such as eosinophils, EM has helped to understand how cells package and release mediators involved in immune responses. Ultrastructural investigations of human eosinophils enabled visualization of secretory processes in detail and identification of a robust, vesicular trafficking essential for the secretion of immune mediators via a non-classical secretory pathway associated with secretory (specific) granules. This vesicular system is mainly organized as large tubular-vesicular carriers (Eosinophil Sombrero Vesicles - EoSVs) actively formed in response to cell activation and provides a sophisticated structural mechanism for delivery of granule-stored mediators. In this review, we highlight the application of EM techniques to recognize pools of immune mediators at vesicular compartments and to understand the complex secretory pathway within human eosinophils involved in inflammatory and allergic responses. Copyright © 2016 Elsevier Inc. All rights reserved.

Multiple rare variants in the etiology of autism spectrum disorders

PubMed Central

Buxbaum, Joseph D.

2009-01-01

Recent studies in autism spectrum disorders (ASDs) support an important role for multiple rare variants in these conditions. This is a clinically important finding, as, with the demonstration that a significant proportion of ASDs are the result of rare, etiological genetic variants, it becomes possible to make use of genetic testing to supplement behavioral analyses for an earlier diagnosis. As it appears that earlier interventions in ASDs will produce better outcomes, the development of genetic testing to augment behaviorally based evaluations in ASDs holds promise for improved treatment. Furthermore, these rare variants involve synaptic and neuronal genes that implicate specific paihvi/ays, cells, and subcellular compartments in ASDs, which in turn will suggest novel therapeutic approaches in ASDs, Of particular recent interest are the synaptic cell adhesion and associated molecules, including neurexin 1, neuroligin 3 and 4, and SHANK3, which implicate glutamatergic synapse abnormalities in ASDs, In the current review we will overview the evidence for a genetic etiology for ASDs, and summarize recent genetic findings in these disorders. PMID:19432386

miR-191 and miR-135 are required for long-lasting spine remodelling associated with synaptic long-term depression

NASA Astrophysics Data System (ADS)

Hu, Zhonghua; Yu, Danni; Gu, Qin-Hua; Yang, Yanqin; Tu, Kang; Zhu, Jun; Li, Zheng

2014-02-01

Activity-dependent modification of dendritic spines, subcellular compartments accommodating postsynaptic specializations in the brain, is an important cellular mechanism for brain development, cognition and synaptic pathology of brain disorders. NMDA receptor-dependent long-term depression (NMDAR-LTD), a prototypic form of synaptic plasticity, is accompanied by prolonged remodelling of spines. The mechanisms underlying long-lasting spine remodelling in NMDAR-LTD, however, are largely unclear. Here we show that LTD induction causes global changes in miRNA transcriptomes affecting many cellular activities. Specifically, we show that expression changes of miR-191 and miR-135 are required for maintenance but not induction of spine restructuring. Moreover, we find that actin depolymerization and AMPA receptor exocytosis are regulated for extended periods of time by miRNAs to support long-lasting spine plasticity. These findings reveal a miRNA-mediated mechanism and a role for AMPA receptor exocytosis in long-lasting spine plasticity, and identify a number of candidate miRNAs involved in LTD.

Biolayer interferometry of lipid nanodisc‐reconstituted yeast vacuolar H+‐ATPase

PubMed Central

Sharma, Stuti

2017-01-01

Abstract Vacuolar H+‐ATPase (V‐ATPase) is a large, multisubunit membrane protein complex responsible for the acidification of subcellular compartments and the extracellular space. V‐ATPase activity is regulated by reversible disassembly, resulting in cytosolic V 1‐ATPase and membrane‐integral V 0 proton channel sectors. Reversible disassembly is accompanied by transient interaction with cellular factors and assembly chaperones. Quantifying protein‐protein interactions involving membrane proteins, however, is challenging. Here we present a novel method to determine kinetic constants of membrane protein–protein interactions using biolayer interferometry (BLI). Yeast vacuoles are solubilized, vacuolar proteins are reconstituted into lipid nanodiscs with native vacuolar lipids and biotinylated membrane scaffold protein (MSP) followed by affinity purification of nanodisc‐reconstituted V‐ATPase (V 1 V 0ND). We show that V 1 V 0ND can be immobilized on streptavidin‐coated BLI sensors to quantitate binding of a pathogen derived inhibitor and to measure the kinetics of nucleotide dependent enzyme dissociation. PMID:28241399

Top-Down Characterization of the Post-Translationally Modified Intact Periplasmic Proteome from the Bacterium Novosphingobium aromaticivorans

DOE PAGES

Wu, Si; Brown, Roslyn N.; Payne, Samuel H.; ...

2013-01-01

The periplasm of Gram-negative bacteria is a dynamic and physiologically important subcellular compartment where the constant exposure to potential environmental insults amplifies the need for proper protein folding and modifications. Top-down proteomics analysis of the periplasmic fraction at the intact protein level provides unrestricted characterization and annotation of the periplasmic proteome, including the post-translational modifications (PTMs) on these proteins. Here, we used single-dimension ultra-high pressure liquid chromatography coupled with the Fourier transform mass spectrometry (FTMS) to investigate the intact periplasmic proteome of Novosphingobium aromaticivorans . Our top-down analysis provided the confident identification of 55 proteins in the periplasm and characterizedmore » their PTMs including signal peptide removal, N-terminal methionine excision, acetylation, glutathionylation, pyroglutamate, and disulfide bond formation. This study provides the first experimental evidence for the expression and periplasmic localization of many hypothetical and uncharacterized proteins and the first unrestrictive, large-scale data on PTMs in the bacterial periplasm.« less

Biolayer interferometry of lipid nanodisc-reconstituted yeast vacuolar H+ -ATPase.

PubMed

Sharma, Stuti; Wilkens, Stephan

2017-05-01

Vacuolar H + -ATPase (V-ATPase) is a large, multisubunit membrane protein complex responsible for the acidification of subcellular compartments and the extracellular space. V-ATPase activity is regulated by reversible disassembly, resulting in cytosolic V 1 -ATPase and membrane-integral V 0 proton channel sectors. Reversible disassembly is accompanied by transient interaction with cellular factors and assembly chaperones. Quantifying protein-protein interactions involving membrane proteins, however, is challenging. Here we present a novel method to determine kinetic constants of membrane protein-protein interactions using biolayer interferometry (BLI). Yeast vacuoles are solubilized, vacuolar proteins are reconstituted into lipid nanodiscs with native vacuolar lipids and biotinylated membrane scaffold protein (MSP) followed by affinity purification of nanodisc-reconstituted V-ATPase (V 1 V 0 ND). We show that V 1 V 0 ND can be immobilized on streptavidin-coated BLI sensors to quantitate binding of a pathogen derived inhibitor and to measure the kinetics of nucleotide dependent enzyme dissociation. © 2017 The Protein Society.

Vitamin C: update on physiology and pharmacology

PubMed Central

Mandl, J; Szarka, A; Bánhegyi, G

2009-01-01

Although ascorbic acid is an important water-soluble antioxidant and enzyme cofactor in plants and animals, humans and some other species do not synthesize ascorbate due to the lack of the enzyme catalyzing the final step of the biosynthetic pathway, and for them it has become a vitamin. This review focuses on the role of ascorbate in various hydroxylation reactions and in the redox homeostasis of subcellular compartments including mitochondria and endoplasmic reticulum. Recently discovered functions of ascorbate in nucleic acid and histone dealkylation and proteoglycan deglycanation are also summarized. These new findings might delineate a role for ascorbate in the modulation of both pro- and anti-carcinogenic mechanisms. Recent advances and perspectives in therapeutic applications are also reviewed. On the basis of new and earlier observations, the advantages of the lost ability to synthesize ascorbate are pondered. The increasing knowledge of the functions of ascorbate and of its molecular sites of action can mechanistically substantiate a place for ascorbate in the treatment of various diseases. PMID:19508394

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu C. J.

Hydroxycinnamic acids constitute a large class of phenylpropanoid metabolites that are distributed ubiquitously in terrestrial plants. They occur most frequently as esters, amides or glycosides within the cytosol, the particular subcellular compartments such as the vacuole or the cell wall. Hydroxycinnamate conjugates play a vital role in the plant's growth and development and in its defense responses against biotic- and abiotic-stresses. Furthermore, the incorporation of hydroxycinnamate conjugates into the cell wall is a major factor attenuating the wall's biodegradability. Understanding the biosyntheses of hydroxycinnamate conjugates and its molecular regulation may well facilitate the sustainable production of cell wall biomass, andmore » the efficient conversion of lignocellulosic materials. This paper reviews our current molecular and biochemical understandings on the formation of several classes of hydroxycinnamate esters and amides, including the soluble conjugates and the 'wall-bound' phenolics. It also discusses the emerging biotechnological applications in manipulating hydroxycinnamates to improve the degradability of the cell wall biomass and enhance the production of valuable chemicals and biomaterials.« less

Double labelling of intracellular mitochondria and nucleolus using thiophene pyridium salt with high quantum yield as biosensor and its application in stimulated emission depletion nanoscopy.

PubMed

Tian, Xiaohe; Wang, Hui; Zhang, Qiong; Zhang, Mingzhu; Zhu, Yingzhong; Chen, Yan; Wu, Jieying; Tian, Yupeng

2018-05-30

Probe for dual-site target distinct subcellular compartments from cytosol and nucleus is an attractive approach, however, which was scarcely reported. Herein, a series of small-molecular thiophene pyridium salt derivatives (MitoNuc1-4) possessing water-soluble, high quantum yield and two-photon activity were rationally designed, and their structures were crystallographic confirmed. Systematic photophysical and biological imaging property investigations were carried out for them. It was found that MitoNuc1-4 exhibit two-photon absorption properties in the near infrared region, and MitoNuc1 has membrane permeability and cationic nature, rendering it to be double labelling of mitochondria and nucleolus in living cells with superb photo-stability and non-invasiveness. It also demonstrated that MitoNuc1 in living cells can monitor mitochondrial division in real time and revealed nucleolar ultrastructure under stimulated emission depletion nanoscopy. Copyright © 2017 Elsevier B.V. All rights reserved.

Single-cell and subcellular pharmacokinetic imaging allows insight into drug action in vivo.

PubMed

Thurber, Greg M; Yang, Katy S; Reiner, Thomas; Kohler, Rainer H; Sorger, Peter; Mitchison, Tim; Weissleder, Ralph

2013-01-01

Pharmacokinetic analysis at the organ level provides insight into how drugs distribute throughout the body, but cannot explain how drugs work at the cellular level. Here we demonstrate in vivo single-cell pharmacokinetic imaging of PARP-1 inhibitors and model drug behaviour under varying conditions. We visualize intracellular kinetics of the PARP-1 inhibitor distribution in real time, showing that PARP-1 inhibitors reach their cellular target compartment, the nucleus, within minutes in vivo both in cancer and normal cells in various cancer models. We also use these data to validate predictive finite element modelling. Our theoretical and experimental data indicate that tumour cells are exposed to sufficiently high PARP-1 inhibitor concentrations in vivo and suggest that drug inefficiency is likely related to proteomic heterogeneity or insensitivity of cancer cells to DNA-repair inhibition. This suggests that single-cell pharmacokinetic imaging and derived modelling improve our understanding of drug action at single-cell resolution in vivo.

Beyond Fluorescent Proteins: Hybrid and Bioluminescent Indicators for Imaging Neural Activities.

PubMed

Wang, Anqi; Feng, Jiesi; Li, Yulong; Zou, Peng

2018-04-18

Optical biosensors have been invaluable tools in neuroscience research, as they provide the ability to directly visualize neural activity in real time, with high specificity, and with exceptional spatial and temporal resolution. Notably, a majority of these sensors are based on fluorescent protein scaffolds, which offer the ability to target specific cell types or even subcellular compartments. However, fluorescent proteins are intrinsically bulky tags, often insensitive to the environment, and always require excitation light illumination. To address these limitations, there has been a proliferation of alternative sensor scaffolds developed in recent years, including hybrid sensors that combine the advantages of synthetic fluorophores and genetically encoded protein tags, as well as bioluminescent probes. While still in their early stage of development as compared with fluorescent protein-based sensors, these novel probes have offered complementary solutions to interrogate various aspects of neuronal communication, including transmitter release, changes in membrane potential, and the production of second messengers. In this Review, we discuss these important new developments with a particular focus on design strategies.

Inverse problems and computational cell metabolic models: a statistical approach

NASA Astrophysics Data System (ADS)

Calvetti, D.; Somersalo, E.

2008-07-01

In this article, we give an overview of the Bayesian modelling of metabolic systems at the cellular and subcellular level. The models are based on detailed description of key biochemical reactions occurring in tissue, which may in turn be compartmentalized into cytosol and mitochondria, and of transports between the compartments. The classical deterministic approach which models metabolic systems as dynamical systems with Michaelis-Menten kinetics, is replaced by a stochastic extension where the model parameters are interpreted as random variables with an appropriate probability density. The inverse problem of cell metabolism in this setting consists of estimating the density of the model parameters. After discussing some possible approaches to solving the problem, we address the issue of how to assess the reliability of the predictions of a stochastic model by proposing an output analysis in terms of model uncertainties. Visualization modalities for organizing the large amount of information provided by the Bayesian dynamic sensitivity analysis are also illustrated.

Profiling Synaptic Proteins Identifies Regulators of Insulin Secretion and Lifespan

PubMed Central

Kaplan, Joshua M.

2008-01-01

Cells are organized into distinct compartments to perform specific tasks with spatial precision. In neurons, presynaptic specializations are biochemically complex subcellular structures dedicated to neurotransmitter secretion. Activity-dependent changes in the abundance of presynaptic proteins are thought to endow synapses with different functional states; however, relatively little is known about the rules that govern changes in the composition of presynaptic terminals. We describe a genetic strategy to systematically analyze protein localization at Caenorhabditis elegans presynaptic specializations. Nine presynaptic proteins were GFP-tagged, allowing visualization of multiple presynaptic structures. Changes in the distribution and abundance of these proteins were quantified in 25 mutants that alter different aspects of neurotransmission. Global analysis of these data identified novel relationships between particular presynaptic components and provides a new method to compare gene functions by identifying shared protein localization phenotypes. Using this strategy, we identified several genes that regulate secretion of insulin-like growth factors (IGFs) and influence lifespan in a manner dependent on insulin/IGF signaling. PMID:19043554

Rich do not rise early: spatio-temporal patterns in the mobility networks of different socio-economic classes

PubMed Central

Hurtado, Rafael G.; Floría, Luis Mario

2016-01-01

We analyse the urban mobility in the cities of Medellín and Manizales (Colombia). Each city is represented by six mobility networks, each one encoding the origin-destination trips performed by a subset of the population corresponding to a particular socio-economic status. The nodes of each network are the different urban locations whereas links account for the existence of a trip between two different areas of the city. We study the main structural properties of these mobility networks by focusing on their spatio-temporal patterns. Our goal is to relate these patterns with the partition into six socio-economic compartments of these two societies. Our results show that spatial and temporal patterns vary across these socio-economic groups. In particular, the two datasets show that as wealth increases the early-morning activity is delayed, the midday peak becomes smoother and the spatial distribution of trips becomes more localized. PMID:27853531

[Indications and Borderline Indications for Medial Mobile Bearing Unicondylar Knee Replacement].

PubMed

Walker, T; Streit, M R; Streit, J; Gotterbarm, T; Aldinger, P R

2015-10-01

Beside the possibility of bicondylar knee replacement, patients with isolated anteromedial osteoarthritis also have the possibility of unicondylar knee replacement. Therefore some requirements are essential such as functionally intact cruciate and collateral ligaments, intact cartilage in the lateral compartment and an intraoperative flexion of more than 100°. An instability or contracture of the cruciate or collateral ligaments, a varus deformity more than 15°, a flexion deformity of more than 15°, an intraoperative flexion less than 100° as well as failed upper tibial osteotomy are seen as contraindications. In addition, a rheumatoid arthritis and a full thickness cartilage defect in the central part of the lateral compartment are seen as a contraindication because of the risk of a progression of the disease. With respect to these contraindications, excellent functional outcome and survival rates could be demonstrated in the long term. An expansion of these criteria, especially in patients with an insufficiency of the cruciate ligaments or after failed upper tibial osteotomy should only be done in certain cases after careful assessment of the benefits and risks. These patients should be informed about the lack of long-term results and the higher risk of complications. Quite commonly, the criteria of Kozinn and Scott are used for patient selection. These criteria were originally established for fixed-bearing prosthesis and have no relevance on mobile-bearing prosthesis. Criteria such as age, level of activity, weight, chondrocalcinosis and anterior knee pain have no effect on the clinical outcome or the long-term survival of a mobile-bearing prosthesis. Georg Thieme Verlag KG Stuttgart · New York.

Burn Resuscitation Decision Support System (BRDSS)

DTIC Science & Technology

2014-11-01

agreement was to package the software into a mobile device (the BRDSS-M, trade name Burn Navigator™) with substantial input from caregivers at the USAISR...combat casualties with >30% TBSA burns developed abdominal compartment syndrome (ACS) and perished.2 Between January 2006 and June 2007, after the...or even an open-loop system, could integrate the urine output monitor and infusion pump and free up the caregiver from manual data entry tasks to

Bacterial diversity and antibiotic resistance in water habitats: searching the links with the human microbiome.

PubMed

Vaz-Moreira, Ivone; Nunes, Olga C; Manaia, Célia M

2014-07-01

Water is one of the most important bacterial habitats on Earth. As such, water represents also a major way of dissemination of bacteria between different environmental compartments. Human activities led to the creation of the so-called urban water cycle, comprising different sectors (waste, surface, drinking water), among which bacteria can hypothetically be exchanged. Therefore, bacteria can be mobilized between unclean water habitats (e.g. wastewater) and clean or pristine water environments (e.g. disinfected and spring drinking water) and eventually reach humans. In addition, bacteria can also transfer mobile genetic elements between different water types, other environments (e.g. soil) and humans. These processes may involve antibiotic resistant bacteria and antibiotic resistance genes. In this review, the hypothesis that some bacteria may share different water compartments and be also hosted by humans is discussed based on the comparison of the bacterial diversity in different types of water and with the human-associated microbiome. The role of such bacteria as potential disseminators of antibiotic resistance and the inference that currently only a small fraction of the clinically relevant antibiotic resistome may be known is discussed. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

α1b-Adrenergic Receptor Localization and Relationship to the D1-Dopamine Receptor in the Rat Nucleus Accumbens.

PubMed

Mitrano, Darlene A; Jackson, Kelsey; Finley, Samantha; Seeley, Allison

2018-02-10

The α1-adrenergic receptors (α1ARs) have been implicated in numerous actions of the brain, including attention and wakefulness. Additionally, they have been identified as contributing to disorders of the brain, such as drug addiction, and recent work has shown a role of these receptors in relapse to psychostimulants. While some functionality is known, the actual subcellular localization of the subtypes of the α1ARs remains to be elucidated. Further, their anatomical relationship to receptors for other neurotransmitters, such as dopamine (DA), remains unclear. Therefore, using immunohistochemistry and electron microscopy techniques, this study describes the subcellular localization of the α1b-adrenergic receptor (α1bAR), the subtype most tied to relapse behaviors, as well as its relationship to the D1-dopamine receptor (D1R) in both the shell and core of the rat nucleus accumbens (NAc). Overall, α1bARs were found in unmyelinated axons and axon terminals with some labeling in dendrites. In accordance with other studies of the striatum, the D1R was found mainly in dendrites and spines; therefore, colocalization of the D1R with the α1bAR was rare postsynaptically. However, in the NAc shell, when the receptors were co-expressed in the same neuronal elements there was a trend for both receptors to be found on the plasma membrane, as opposed to the intracellular compartment. This study provides valuable anatomical information about the α1bAR and its relationship to the D1R and the regulation of DA and norepinephrine (NE) neurotransmission in the brain which have been examined previously. Published by Elsevier Ltd.

Integration of a constraint-based metabolic model of Brassica napus developing seeds with 13C-metabolic flux analysis

PubMed Central

Hay, Jordan O.; Shi, Hai; Heinzel, Nicolas; Hebbelmann, Inga; Rolletschek, Hardy; Schwender, Jorg

2014-01-01

The use of large-scale or genome-scale metabolic reconstructions for modeling and simulation of plant metabolism and integration of those models with large-scale omics and experimental flux data is becoming increasingly important in plant metabolic research. Here we report an updated version of bna572, a bottom-up reconstruction of oilseed rape (Brassica napus L.; Brassicaceae) developing seeds with emphasis on representation of biomass-component biosynthesis. New features include additional seed-relevant pathways for isoprenoid, sterol, phenylpropanoid, flavonoid, and choline biosynthesis. Being now based on standardized data formats and procedures for model reconstruction, bna572+ is available as a COBRA-compliant Systems Biology Markup Language (SBML) model and conforms to the Minimum Information Requested in the Annotation of Biochemical Models (MIRIAM) standards for annotation of external data resources. Bna572+ contains 966 genes, 671 reactions, and 666 metabolites distributed among 11 subcellular compartments. It is referenced to the Arabidopsis thaliana genome, with gene-protein-reaction (GPR) associations resolving subcellular localization. Detailed mass and charge balancing and confidence scoring were applied to all reactions. Using B. napus seed specific transcriptome data, expression was verified for 78% of bna572+ genes and 97% of reactions. Alongside bna572+ we also present a revised carbon centric model for 13C-Metabolic Flux Analysis (13C-MFA) with all its reactions being referenced to bna572+ based on linear projections. By integration of flux ratio constraints obtained from 13C-MFA and by elimination of infinite flux bounds around thermodynamically infeasible loops based on COBRA loopless methods, we demonstrate improvements in predictive power of Flux Variability Analysis (FVA). Using this combined approach we characterize the difference in metabolic flux of developing seeds of two B. napus genotypes contrasting in starch and oil content. PMID:25566296

Effects of simulated solar radiation on the bioaccumulation of polycyclic aromatic hydrocarbons by the duckweed, Lemna gibba

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duxbury, C.L.; Dixon, D.G.; Greenberg, B.M.

1997-08-01

Light (particularly ultraviolet B) results in photomodification of polycyclic aromatic hydrocarbons (PAHs) to products with increased polarity and water solubility and enhanced toxicity relative to the parent compounds. The uptake and depuration kinetics of three representative PAHs, anthracene (ANT), phenanthrene (PHE), and benzo[a]pyrene (BAP), and their photomodified products were determined for Lemna gibba. The {sup 14}C-labeled PAHs were delivered to the plants in their aqueous growth medium either via a dimethylsulfoxide (DMSO) carrier or adsorbed directly to sand placed in the medium. Assimilation was carried out under simulated solar radiation (SSR) and in darkness. The potential sites of PAH actionmore » within the plants were defined by identifying the subcellular location of both intact and photomodified PAHs following assimilation. Lemna gibba had a high capacity for intact ANT, PHE, and BAP in the dark regardless of the two routes of delivery. Depuration was also rapid. Net assimilation of all three PAHs in the dark was always higher when the chemicals were delivered with DMSO than from sand, although first-order kinetics were apparent with both delivery systems. The relative levels of assimilation were PHE > ANT > BAP. Polycyclic aromatic hydrocarbons were rapidly assimilated under SSR, albeit net assimilation for both the intact and photomodified forms was generally lower under SSR compared with darkness. This was also reflected in the bioconcentration factors, which were highest in darkness for each PAH and dropped significantly under SSR and after photomodification. Both intact and photooxidized PAHs accumulated preferentially in the thylakoids and microsomes of L. gibba, suggesting these to be the subcellular compartments most at risk from PAH damage.« less

Different pools of glutamate receptors mediate sensitivity to ambient glutamate in the cochlear nucleus.

PubMed

Yang, Yang; Xu-Friedman, Matthew A

2015-06-01

Ambient glutamate plays an important role in pathological conditions, such as stroke, but its role during normal activity is not clear. In addition, it is not clear how ambient glutamate acts on glutamate receptors with varying affinities or subcellular localizations. To address this, we studied "endbulb of Held" synapses, which are formed by auditory nerve fibers onto bushy cells (BCs) in the anteroventral cochlear nucleus. When ambient glutamate was increased by applying the glutamate reuptake inhibitor TFB-TBOA, BCs depolarized as a result of activation of N-methyl-D-aspartate receptors (NMDARs) and group I metabotropic glutamate receptors (mGluRs). Application of antagonists against NMDARs (in 0 Mg(2+)) or mGluRs caused hyperpolarization, indicating that these receptors were bound by a tonic source of glutamate. AMPA receptors did not show these effects, consistent with their lower glutamate affinity. We also evaluated the subcellular localization of the receptors activated by ambient glutamate. The mGluRs were not activated by synaptic stimulation and thus appear to be exclusively extrasynaptic. By contrast, NMDARs in both synaptic and extrasynaptic compartments were activated by ambient glutamate, as shown using the use-dependent antagonist MK-801. Levels of ambient glutamate appeared to be regulated in a spike-independent manner, and glia likely play a major role. These low levels of ambient glutamate likely have functional consequences, as even low concentrations of TBOA caused significant increases in BC spiking following synaptic stimulation. These results indicate that normal resting potential appears to be poised in the region of maximal sensitivity to small changes in ambient glutamate. Copyright © 2015 the American Physiological Society.

Leaf Oil Body Functions as a Subcellular Factory for the Production of a Phytoalexin in Arabidopsis1[W

PubMed Central

Shimada, Takashi L.; Takano, Yoshitaka; Shimada, Tomoo; Fujiwara, Masayuki; Fukao, Yoichiro; Mori, Masashi; Okazaki, Yozo; Saito, Kazuki; Sasaki, Ryosuke; Aoki, Koh; Hara-Nishimura, Ikuko

2014-01-01

Oil bodies are intracellular structures present in the seed and leaf cells of many land plants. Seed oil bodies are known to function as storage compartments for lipids. However, the physiological function of leaf oil bodies is unknown. Here, we show that leaf oil bodies function as subcellular factories for the production of a stable phytoalexin in response to fungal infection and senescence. Proteomic analysis of oil bodies prepared from Arabidopsis (Arabidopsis thaliana) leaves identified caleosin (CLO3) and α-dioxygenase (α-DOX1). Both CLO3 and α-DOX1 were localized on the surface of oil bodies. Infection with the pathogenic fungus Colletotrichum higginsianum promoted the formation of CLO3- and α-DOX1-positive oil bodies in perilesional areas surrounding the site of infection. α-DOX1 catalyzes the reaction from α-linolenic acid (a major fatty acid component of oil bodies) to an unstable compound, 2-hydroperoxy-octadecatrienoic acid (2-HPOT). Intriguingly, a combination of α-DOX1 and CLO3 produced a stable compound, 2-hydroxy-octadecatrienoic acid (2-HOT), from α-linolenic acid. This suggests that the colocalization of α-DOX1 and CLO3 on oil bodies might prevent the degradation of unstable 2-HPOT by efficiently converting 2-HPOT into the stable compound 2-HOT. We found that 2-HOT had antifungal activity against members of the genus Colletotrichum and that infection with C. higginsianum induced 2-HOT production. These results defined 2-HOT as an Arabidopsis phytoalexin. This study provides, to our knowledge, the first evidence that leaf oil bodies produce a phytoalexin under a pathological condition, which suggests a new mechanism of plant defense. PMID:24214535

Characterization of a Rab11-like GTPase, EhRab11, of Entamoeba histolytica.

PubMed

McGugan, Glen C; Temesvari, Lesly A

2003-07-01

The Entamoeba histolytica Rab11 family of small molecular weight GTPases consists of three members, EhRab11, EhRab11B, and EhRab11C. The functions of these Rabs in Entamoeba have not been determined. Therefore, as an approach to elucidate the role of the Rab11 family of GTPases in Entamoeba, immunofluorescence microscopy was undertaken to define the subcellular localization of one member of this family, EhRab11. Under conditions of growth, EhRab11 displayed a punctate pattern in the cytoplasm of trophozoites. EhRab11 did not colocalize with markers for the Golgi apparatus, endoplasmic reticulum, pinosomes, phagosomes, or compartments formed by receptor-mediated endocytosis, suggesting that this Rab may not play a role in vesicle trafficking between these organelles. Under conditions of iron and serum starvation, EhRab11 was translocated to the periphery of the cell. The altered cellular localization was accompanied by multinucleation of the cells as well as the acquisition of detergent resistance by the cells, features that are characteristic of Entamoeba cysts. The translocation of EhRab11 to the periphery of the cell during iron and serum starvation was specific as the subcellular localizations of two other Rab GTPases, EhRab7 and EhRabA, were not altered under the same conditions. In addition, the formation of multinucleated cells by inhibition of cytokinesis was not sufficient to induce the translocation of EhRab11 to the cell periphery. Taken together, the data suggest that iron and serum starvation may induce encystation in E. histolytica and that EhRab11 may play a role in this process. Moreover, these studies are the first to describe a putative role for a Rab GTPase in encystation in Entamoeba sp.

Functional Analyses of the Crohn's Disease Risk Gene LACC1.

PubMed

Assadi, Ghazaleh; Vesterlund, Liselotte; Bonfiglio, Ferdinando; Mazzurana, Luca; Cordeddu, Lina; Schepis, Danika; Mjösberg, Jenny; Ruhrmann, Sabrina; Fabbri, Alessia; Vukojevic, Vladana; Percipalle, Piergiorgio; Salomons, Florian A; Laurencikiene, Jurga; Törkvist, Leif; Halfvarson, Jonas; D'Amato, Mauro

2016-01-01

Genetic variation in the Laccase (multicopper oxidoreductase) domain-containing 1 (LACC1) gene has been shown to affect the risk of Crohn's disease, leprosy and, more recently, ulcerative colitis and juvenile idiopathic arthritis. LACC1 function appears to promote fatty-acid oxidation, with concomitant inflammasome activation, reactive oxygen species production, and anti-bacterial responses in macrophages. We sought to contribute to elucidating LACC1 biological function by extensive characterization of its expression in human tissues and cells, and through preliminary analyses of the regulatory mechanisms driving such expression. We implemented Western blot, quantitative real-time PCR, immunofluorescence microscopy, and flow cytometry analyses to investigate fatty acid metabolism-immune nexus (FAMIN; the LACC1 encoded protein) expression in subcellular compartments, cell lines and relevant human tissues. Gene-set enrichment analyses were performed to initially investigate modulatory mechanisms of LACC1 expression. A small-interference RNA knockdown in vitro model system was used to study the effect of FAMIN depletion on peroxisome function. FAMIN expression was detected in macrophage-differentiated THP-1 cells and several human tissues, being highest in neutrophils, monocytes/macrophages, myeloid and plasmacytoid dendritic cells among peripheral blood cells. Subcellular co-localization was exclusively confined to peroxisomes, with some additional positivity for organelle endomembrane structures. LACC1 co-expression signatures were enriched for genes involved in peroxisome proliferator-activated receptors (PPAR) signaling pathways, and PPAR ligands downregulated FAMIN expression in in vitro model systems. FAMIN is a peroxisome-associated protein with primary role(s) in macrophages and other immune cells, where its metabolic functions may be modulated by PPAR signaling events. However, the precise molecular mechanisms through which FAMIN exerts its biological effects in immune cells remain to be elucidated.

Activity and subcellular compartmentalization of peroxisome proliferator-activated receptor alpha are altered by the centrosome-associated protein CAP350.

PubMed

Patel, Hansa; Truant, Ray; Rachubinski, Richard A; Capone, John P

2005-01-01

Peroxisome proliferator-activated nuclear hormone receptors (PPAR) are ligand-activated transcription factors that play pivotal roles in governing metabolic homeostasis and cell growth. PPARs are primarily in the nucleus but, under certain circumstances, can be found in the cytoplasm. We show here that PPAR(alpha) interacts with the centrosome-associated protein CAP350. CAP350 also interacts with PPAR(delta), PPAR(gamma) and liver-X-receptor alpha, but not with the 9-cis retinoic acid receptor, RXR(alpha). Immunofluorescence analysis indicated that PPAR(alpha) is diffusely distributed in the nucleus and excluded from the cytoplasm. However, in the presence of coexpressed CAP350, PPAR(alpha) colocalizes with CAP350 to discrete nuclear foci and to the centrosome, perinuclear region and intermediate filaments. In contrast, the subcellular distribution of RXR(alpha) or of thyroid hormone receptor alpha was not altered by coexpression of CAP350. An amino-terminal fragment of CAP350 was localized exclusively to nuclear foci and was sufficient to recruit PPAR(alpha) to these sites. Mutation of the single putative nuclear hormone receptor interacting signature motif LXXLL present in this fragment had no effect on its subnuclear localization but abrogated recruitment of PPAR(alpha) to nuclear foci. Surprisingly, mutation of the LXXLL motif in this CAP350 subfragment did not prevent its binding to PPAR(alpha) in vitro, suggesting that this motif serves some function other than PPAR(alpha) binding in recruiting PPAR(alpha) to nuclear spots. CAP350 inhibited PPAR(alpha)-mediated transactivation in an LXXLL-dependent manner, suggesting that CAP350 represses PPAR(alpha) function. Our findings implicate CAP350 in a dynamic process that recruits PPAR(alpha) to discrete nuclear and cytoplasmic compartments and suggest that altered intracellular compartmentalization represents a regulatory process that modulates PPAR function.

Time scale of diffusion in molecular and cellular biology

NASA Astrophysics Data System (ADS)

Holcman, D.; Schuss, Z.

2014-05-01

Diffusion is the driver of critical biological processes in cellular and molecular biology. The diverse temporal scales of cellular function are determined by vastly diverse spatial scales in most biophysical processes. The latter are due, among others, to small binding sites inside or on the cell membrane or to narrow passages between large cellular compartments. The great disparity in scales is at the root of the difficulty in quantifying cell function from molecular dynamics and from simulations. The coarse-grained time scale of cellular function is determined from molecular diffusion by the mean first passage time of molecular Brownian motion to a small targets or through narrow passages. The narrow escape theory (NET) concerns this issue. The NET is ubiquitous in molecular and cellular biology and is manifested, among others, in chemical reactions, in the calculation of the effective diffusion coefficient of receptors diffusing on a neuronal cell membrane strewn with obstacles, in the quantification of the early steps of viral trafficking, in the regulation of diffusion between the mother and daughter cells during cell division, and many other cases. Brownian trajectories can represent the motion of a molecule, a protein, an ion in solution, a receptor in a cell or on its membrane, and many other biochemical processes. The small target can represent a binding site or an ionic channel, a hidden active site embedded in a complex protein structure, a receptor for a neurotransmitter on the membrane of a neuron, and so on. The mean time to attach to a receptor or activator determines diffusion fluxes that are key regulators of cell function. This review describes physical models of various subcellular microdomains, in which the NET coarse-grains the molecular scale to a higher cellular-level, thus clarifying the role of cell geometry in determining subcellular function.

An intrinsic DFF40/CAD endonuclease deficiency impairs oligonucleosomal DNA hydrolysis during caspase-dependent cell death: a common trait in human glioblastoma cells.

PubMed

Sánchez-Osuna, María; Martínez-Escardó, Laura; Granados-Colomina, Carla; Martínez-Soler, Fina; Pascual-Guiral, Sònia; Iglesias-Guimarais, Victoria; Velasco, Roser; Plans, Gerard; Vidal, Noemi; Tortosa, Avelina; Barcia, Carlos; Bruna, Jordi; Yuste, Victor J

2016-07-01

Glioblastoma (GBM) or grade IV astrocytoma is one of the most devastating human cancers. The loss of DFF40/CAD, the key endonuclease that triggers oligonucleosomal DNA fragmentation during apoptosis, has been linked to genomic instability and cell survival after radiation. Despite the near inevitability of GBM tumor recurrence after treatment, the relationship between DFF40/CAD and GBM remains unexplored. We studied the apoptotic behavior of human GBM-derived cells after apoptotic insult. We analyzed caspase activation and the protein levels and subcellular localization of DFF40/CAD apoptotic endonuclease. DFF40/CAD was also evaluated in histological sections from astrocytic tumors and nontumoral human brain. We showed that GBM cells undergo incomplete apoptosis without generating oligonucleosomal DNA degradation despite the correct activation of executioner caspases. The major defect of GBM cells relied on the improper accumulation of DFF40/CAD at the nucleoplasmic subcellular compartment. Supporting this finding, DFF40/CAD overexpression allowed GBM cells to display oligonucleosomal DNA degradation after apoptotic challenge. Moreover, the analysis of histological slices from astrocytic tumors showed that DFF40/CAD immunoreactivity in tumoral GFAP-positive cells was markedly reduced when compared with nontumoral samples. Our data highlight the low expression levels of DFF40/CAD and the absence of DNA laddering as common molecular traits in GBM. These findings could be of major importance for understanding the malignant behavior of remaining tumor cells after radiochemotherapy. © The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Nitric oxide signaling: systems integration of oxygen balance in defense of cell integrity.

PubMed

Gong, Li; Pitari, Giovanni M; Schulz, Stephanie; Waldman, Scott A

2004-01-01

Nitric oxide has emerged as a ubiquitous signaling molecule subserving diverse pathophysiologic processes, including cardiovascular homeostasis and its decompensation in atherogenesis. Recent insights into molecular mechanisms regulating nitric oxide generation and the rich diversity of mechanisms by which it propagates signals reveal the role of this simple gas as a principle mediator of systems integration of oxygen balance. The molecular lexicon by which nitric oxide propagates signals encompasses the elements of posttranslational modification of proteins by redox-based nitrosylation of transition metal centers and free thiols. Spatial and temporal precision and specificity of signal initiation, amplification, and propagation are orchestrated by dynamic assembly of supramolecular complexes coupling nitric oxide production to upstream and downstream components in specific subcellular compartments. The concept of local paracrine signaling by nitric oxide over subcellular distances for short durations has expanded to include endocrine-like effects over anatomic spatial and temporal scales. From these insights emerges a role for nitric oxide in integrating system responses controlling oxygen supply and demand to defend cell integrity in the face of ischemic challenge. In this context, nitric oxide coordinates the respiratory cycle to acquire and deliver oxygen to target tissues by regulating hemoglobin function and vascular smooth muscle contractility and matches energy supply and demand by down-regulating energy-requiring functions while shifting metabolism to optimize energy production. Insights into mechanisms regulating nitric oxide production and signaling and their integration into responses mediating homeostasis place into specific relief the role of those processes in pathophysiology. Indeed, endothelial dysfunction associated with altered production of nitric oxide regulating tissue integrity contributes to the pathogenesis underlying atherogenesis. Moreover, this central role in pathophysiology identifies nitric oxide signaling as a key target for novel therapeutic interventions to minimize irreversible tissue damage associated with ischemic cardiovascular disease.

Plant Proteins Are Smaller Because They Are Encoded by Fewer Exons than Animal Proteins.

PubMed

Ramírez-Sánchez, Obed; Pérez-Rodríguez, Paulino; Delaye, Luis; Tiessen, Axel

2016-12-01

Protein size is an important biochemical feature since longer proteins can harbor more domains and therefore can display more biological functionalities than shorter proteins. We found remarkable differences in protein length, exon structure, and domain count among different phylogenetic lineages. While eukaryotic proteins have an average size of 472 amino acid residues (aa), average protein sizes in plant genomes are smaller than those of animals and fungi. Proteins unique to plants are ∼81aa shorter than plant proteins conserved among other eukaryotic lineages. The smaller average size of plant proteins could neither be explained by endosymbiosis nor subcellular compartmentation nor exon size, but rather due to exon number. Metazoan proteins are encoded on average by ∼10 exons of small size [∼176 nucleotides (nt)]. Streptophyta have on average only ∼5.7 exons of medium size (∼230nt). Multicellular species code for large proteins by increasing the exon number, while most unicellular organisms employ rather larger exons (>400nt). Among subcellular compartments, membrane proteins are the largest (∼520aa), whereas the smallest proteins correspond to the gene ontology group of ribosome (∼240aa). Plant genes are encoded by half the number of exons and also contain fewer domains than animal proteins on average. Interestingly, endosymbiotic proteins that migrated to the plant nucleus became larger than their cyanobacterial orthologs. We thus conclude that plants have proteins larger than bacteria but smaller than animals or fungi. Compared to the average of eukaryotic species, plants have ∼34% more but ∼20% smaller proteins. This suggests that photosynthetic organisms are unique and deserve therefore special attention with regard to the evolutionary forces acting on their genomes and proteomes. Copyright © 2016 The Authors. Production and hosting by Elsevier Ltd.. All rights reserved.

Cloning, localization and expression analysis of vacuolar sugar transporters in the CAM plant Ananas comosus (pineapple).

PubMed

Antony, Edna; Taybi, Tahar; Courbot, Mikaël; Mugford, Sam T; Smith, J Andrew C; Borland, Anne M

2008-01-01

In photosynthetic tissues of the CAM plant pineapple (Ananas comosus), storage of soluble sugars in the central vacuole during the daytime and their remobilization at night is required to provide carbon skeletons for nocturnal CO(2) fixation. However, soluble sugars produced photosynthetically must also be exported to support growth processes in heterotrophic tissues. To begin to address how vacuolar sugar storage and assimilate partitioning are regulated in A. comosus, degenerate PCR and cDNA library screening were used to clone three candidate sugar transporters from the leaves of this species. Subcellular localization of the three transporters was investigated via expression of YFP-fusion proteins in tobacco epidermal cells and their co-localization with subcellular markers by confocal microscopy. Using this strategy, a putative hexose transporter (AcMST1) and a putative inositol transporter (AcINT1) were identified that both localized to the tonoplast, whereas a putative sucrose transporter (AcSUT1) was found to localize to prevacuolar compartments. A cDNA (AcMST2) with high similarity to a recently characterized tonoplast hexose transporter in Arabidopsis was also identified from an A. comosus fruit EST database. Analyses of transcript abundance indicated that AcMST1 was more highly expressed in fruits compared to leaves of A. comosus, whilst transcripts of AcINT1, AcSUT1, and AcMST2 were more abundant in leaves. Transcript abundance of AcINT1, the putative inositol transporter, showed day-night changes comparable to those of other CAM-related transcripts described in Mesembryanthemum crystallinum. The results are discussed in terms of the role of vacuolar sugar transporters in regulating carbon flow during the diel cycle in CAM plants.

Differential subcellular membrane recruitment of Src may specify its downstream signalling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diesbach, Philippe de; Medts, Thierry; Carpentier, Sarah

2008-04-15

Most Src family members are diacylated and constitutively associate with membrane 'lipid rafts' that coordinate signalling. Whether the monoacylated Src, frequently hyperactive in carcinomas, also localizes at 'rafts' remains controversial. Using polarized MDCK cells expressing the thermosensitive v-Src/tsLA31 variant, we here addressed how Src tyrosine-kinase activation may impact on its (i) membrane recruitment, in particular to 'lipid rafts'; (ii) subcellular localization; and (iii) signalling. The kinetics of Src-kinase thermoactivation correlated with its recruitment from the cytosol to sedimentable membranes where Src largely resisted solubilisation by non-ionic detergents at 4 deg. C and floated into sucrose density gradients like caveolin-1 andmore » flotillin-2, i.e. 'lipid rafts'. By immunofluorescence, activated Src showed a dual localization, at apical endosomes/macropinosomes and at the apical plasma membrane. The plasma membrane Src pool did not colocalize with caveolin-1 and flotillin-2, but extensively overlapped GM1 labelling by cholera toxin. Severe ({approx} 70%) cholesterol extraction with methyl-{beta}-cyclodextrin (M{beta}CD) did not abolish 'rafts' floatation, but strongly decreased Src association with floating 'rafts' and abolished its localization at the apical plasma membrane. Src activation independently activated first the MAP-kinase - ERK1/2 pathway, then the PI3-kinase - Akt pathway. MAP-kinase - ERK1/2 activation was insensitive to M{beta}CD, which suppressed Akt phosphorylation and apical endocytosis induced by Src, both depending on the PI3-kinase pathway. We therefore suggest that activated Src is recruited at two membrane compartments, allowing differential signalling, first via ERK1/2 at 'non-raft' domains on endosomes, then via PI3-kinase-Akt on a distinct set of 'rafts' at the apical plasma membrane. Whether this model is applicable to c-Src remains to be examined.« less

Sex Differences in the Subcellular Distribution of Corticotropin-Releasing Factor Receptor 1 in the Rat Hippocampus following Chronic Immobilization Stress.

PubMed

McAlinn, Helena R; Reich, Batsheva; Contoreggi, Natalina H; Kamakura, Renata Poulton; Dyer, Andreina G; McEwen, Bruce S; Waters, Elizabeth M; Milner, Teresa A

2018-07-15

Corticotropin-releasing factor receptors (CRFR1) contribute to stress-induced adaptations in hippocampal structure and function that can affect learning and memory processes. Our prior studies showed that female rats with elevated estrogens compared to males have more plasmalemmal CRFR1 in CA1 pyramidal cells, suggesting a greater sensitivity to stress. Here, we examined the distribution of hippocampal CRFR1 following chronic immobilization stress (CIS) in female and male rats using immuno-electron microscopy. Without stress, total CRFR1 dendritic levels were higher in females in CA1 and in males in the hilus; moreover, plasmalemmal CRFR1 was elevated in pyramidal cell dendrites in CA1 in females and in CA3 in males. Following CIS, near-plasmalemmal CRFR1 increased in CA1 pyramidal cell dendrites in males but not to levels of control or CIS females. In CA3 and the hilus, CIS decreased cytoplasmic and total CRFR1 in dendrites in males only. These results suggest that in naive rats, CRF could induce a greater activation of CA1 pyramidal cells in females than males. Moreover, after CIS, which leads to even greater sex differences in CRFR1 by trafficking it to different subcellular compartments, CRF could enhance activation of CA1 pyramidal cells in males but to a lesser extent than either unstressed or CIS females. Additionally, CA3 pyramidal cells and inhibitory interneurons in males have heightened sensitivity to CRF, regardless of stress state. These sex differences in CRFR1 distribution and trafficking in the hippocampus may contribute to reported sex differences in hippocampus-dependent learning processes in baseline conditions and following chronic stress. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

The Fusarium oxysporum gnt2, Encoding a Putative N-Acetylglucosamine Transferase, Is Involved in Cell Wall Architecture and Virulence

PubMed Central

López-Fernández, Loida; Ruiz-Roldán, Carmen; Pareja-Jaime, Yolanda; Prieto, Alicia; Khraiwesh, Husam; Roncero, M. Isabel G.

2013-01-01

With the aim to decipher the molecular dialogue and cross talk between Fusarium oxysporum f.sp. lycopersci and its host during infection and to understand the molecular bases that govern fungal pathogenicity, we analysed genes presumably encoding N-acetylglucosaminyl transferases, involved in glycosylation of glycoproteins, glycolipids, proteoglycans or small molecule acceptors in other microorganisms. In silico analysis revealed the existence of seven putative N-glycosyl transferase encoding genes (named gnt) in F. oxysporum f.sp. lycopersici genome. gnt2 deletion mutants showed a dramatic reduction in virulence on both plant and animal hosts. Δgnt2 mutants had αalterations in cell wall properties related to terminal αor β-linked N-acetyl glucosamine. Mutant conidia and germlings also showed differences in structure and physicochemical surface properties. Conidial and hyphal aggregation differed between the mutant and wild type strains, in a pH independent manner. Transmission electron micrographs of germlings showed strong cell-to-cell adherence and the presence of an extracellular chemical matrix. Δgnt2 cell walls presented a significant reduction in N-linked oligosaccharides, suggesting the involvement of Gnt2 in N-glycosylation of cell wall proteins. Gnt2 was localized in Golgi-like sub-cellular compartments as determined by fluorescence microscopy of GFP::Gnt2 fusion protein after treatment with the antibiotic brefeldin A or by staining with fluorescent sphingolipid BODIPY-TR ceramide. Furthermore, density gradient ultracentrifugation allowed co-localization of GFP::Gnt2 fusion protein and Vps10p in subcellular fractions enriched in Golgi specific enzymatic activities. Our results suggest that N-acetylglucosaminyl transferases are key components for cell wall structure and influence interactions of F. oxysporum with both plant and animal hosts during pathogenicity. PMID:24416097

Redirecting the Cyanobacterial Bicarbonate Transporters BicA and SbtA to the Chloroplast Envelope: Soluble and Membrane Cargos Need Different Chloroplast Targeting Signals in Plants

PubMed Central

Rolland, Vivien; Badger, Murray R.; Price, G. Dean

2016-01-01

Most major crops used for human consumption are C3 plants, which yields are limited by photosynthetic inefficiency. To circumvent this, it has been proposed to implement the cyanobacterial CO2-concentrating mechanism (CCM), principally consisting of bicarbonate transporters and carboxysomes, into plant chloroplasts. As it is currently not possible to recover homoplasmic transplastomic monocots, foreign genes must be introduced in these plants via nuclear transformation. Consequently, it is paramount to ensure that resulting proteins reach the appropriate sub-cellular compartment, which for cyanobacterial transporters BicA and SbtA, is the chloroplast inner-envelope membrane (IEM). At present, targeting signals to redirect large transmembrane proteins from non-chloroplastic organisms to plant chloroplast envelopes are unknown. The goal of this study was to identify such signals, using agrobacteria-mediated transient expression and confocal microscopy to determine the sub-cellular localization of ∼37 GFP-tagged chimeras. Initially, fragments of chloroplast proteins known to target soluble cargos to the stroma were tested for their ability to redirect BicA, but they proved ineffective. Next, different N-terminal regions from Arabidopsis IEM transporters were tested. We demonstrated that the N-terminus of AtHP59, AtPLGG1 or AtNTT1 (92–115 amino acids), containing a cleavable chloroplast transit peptide (cTP) and a membrane protein leader (MPL), was sufficient to redirect BicA or SbtA to the chloroplast envelope. This constitutes the first evidence that nuclear-encoded transmembrane proteins from non-chloroplastic organisms can be targeted to the envelope of plant chloroplasts; a finding which represents an important advance in chloroplast engineering by opening up the door to further manipulation of the chloroplastic envelope. PMID:26973659

Deg proteases and their role in protein quality control and processing in different subcellular compartments of the plant cell.

PubMed

Schuhmann, Holger; Adamska, Iwona

2012-05-01

Degradation of periplasmic proteins (Deg)/high temperature requirement A (HtrA) proteases are ATP-independent serine endopeptidases found in almost every organism. Database searches revealed that 16 Deg paralogues are encoded by the genome of Arabidopsis thaliana, six of which were experimentally shown to be located in chloroplasts, one in peroxisomes, one in mitochondria and one in the nucleus. Two more Deg proteases are predicted to reside in chloroplasts, five in mitochondria (one of them with a dual chloroplastidial/mitochondrial localization) and the subcellular location of one protein is uncertain. This review summarizes the current knowledge on the role of Deg proteases in maintaining protein homeostasis and protein processing in various subcompartments of the plant cell. The chloroplast Deg proteases are the best examined so far, especially with respect to their role in the degradation of photodamaged photosynthetic proteins and in biogenesis of photosystem II (PSII). A combined action of thylakoid lumen and stroma Deg proteases in the primary cleavage of photodamaged D1 protein from PSII reaction centre is discussed on the basis of a recently resolved crystal structure of plant Deg1. The peroxisomal Deg protease is a processing enzyme responsible for the cleavage of N-terminal peroxisomal targeting signals (PTSs). A. thaliana mutants lacking this enzyme show reduced peroxisomal β-oxidation, indicating for the first time the impact of protein processing on peroxisomal functions in plants. Much less data is available for mitochondrial and nuclear Deg proteases. Based on the available expression data we hypothesize a role in general protein quality control and during acquired heat resistance. Copyright © Physiologia Plantarum 2011.

Focus small to find big - the microbeam story.

PubMed

Wu, Jinhua; Hei, Tom K

2017-08-29

Even though the first ultraviolet microbeam was described by S. Tschachotin back in 1912, the development of sophisticated micro-irradiation facilities only began to flourish in the late 1980s. In this article, we highlight significant microbeam experiments, describe the latest microbeam irradiator configurations and critical discoveries made by using the microbeam apparatus. Modern radiological microbeams facilities are capable of producing a beam size of a few micrometers, or even tens of nanometers in size, and can deposit radiation with high precision within a cellular target. In the past three decades, a variety of microbeams has been developed to deliver a range of radiations including charged particles, X-rays, and electrons. Despite the original intention for their development to measure the effects of a single radiation track, the ability to target radiation with microbeams at sub-cellular targets has been extensively used to investigate radiation-induced biological responses within cells. Studies conducted using microbeams to target specific cells in a tissue have elucidated bystander responses, and further studies have shown reactive oxygen species (ROS) and reactive nitrogen species (RNS) play critical roles in the process. The radiation-induced abscopal effect, which has a profound impact on cancer radiotherapy, further reaffirmed the importance of bystander effects. Finally, by targeting sub-cellular compartments with a microbeam, we have reported cytoplasmic-specific biological responses. Despite the common dogma that nuclear DNA is the primary target for radiation-induced cell death and carcinogenesis, studies conducted using microbeam suggested that targeted cytoplasmic irradiation induces mitochondrial dysfunction, cellular stress, and genomic instability. A more recent development in microbeam technology includes application of mouse models to visualize in vivo DNA double-strand breaks. Microbeams are making important contributions towards our understanding of radiation responses in cells and tissue models.

Dengue Virus Selectively Annexes Endoplasmic Reticulum-Associated Translation Machinery as a Strategy for Co-opting Host Cell Protein Synthesis.

PubMed

Reid, David W; Campos, Rafael K; Child, Jessica R; Zheng, Tianli; Chan, Kitti Wing Ki; Bradrick, Shelton S; Vasudevan, Subhash G; Garcia-Blanco, Mariano A; Nicchitta, Christopher V

2018-04-01

A primary question in dengue virus (DENV) biology is the molecular strategy for recruitment of host cell protein synthesis machinery. Here, we combined cell fractionation, ribosome profiling, and transcriptome sequencing (RNA-seq) to investigate the subcellular organization of viral genome translation and replication as well as host cell translation and its response to DENV infection. We report that throughout the viral life cycle, DENV plus- and minus-strand RNAs were highly partitioned to the endoplasmic reticulum (ER), identifying the ER as the primary site of DENV translation. DENV infection was accompanied by an ER compartment-specific remodeling of translation, where ER translation capacity was subverted from host transcripts to DENV plus-strand RNA, particularly at late stages of infection. Remarkably, translation levels and patterns in the cytosol compartment were only modestly affected throughout the experimental time course of infection. Comparisons of ribosome footprinting densities of the DENV plus-strand RNA and host mRNAs indicated that DENV plus-strand RNA was only sparsely loaded with ribosomes. Combined, these observations suggest a mechanism where ER-localized translation and translational control mechanisms, likely cis encoded, are used to repurpose the ER for DENV virion production. Consistent with this view, we found ER-linked cellular stress response pathways commonly associated with viral infection, namely, the interferon response and unfolded protein response, to be only modestly activated during DENV infection. These data support a model where DENV reprograms the ER protein synthesis and processing environment to promote viral survival and replication while minimizing the activation of antiviral and proteostatic stress response pathways. IMPORTANCE DENV, a prominent human health threat with no broadly effective or specific treatment, depends on host cell translation machinery for viral replication, immune evasion, and virion biogenesis. The molecular mechanism by which DENV commandeers the host cell protein synthesis machinery and the subcellular organization of DENV replication and viral protein synthesis is poorly understood. Here, we report that DENV has an almost exclusively ER-localized life cycle, with viral replication and translation largely restricted to the ER. Surprisingly, DENV infection largely affects only ER-associated translation, with relatively modest effects on host cell translation in the cytosol. DENV RNA translation is very inefficient, likely representing a strategy to minimize disruption of ER proteostasis. Overall these findings demonstrate that DENV has evolved an ER-compartmentalized life cycle; thus, targeting the molecular signatures and regulation of the DENV-ER interaction landscape may reveal strategies for therapeutic intervention. Copyright © 2018 American Society for Microbiology.

The effects of bound state motion on macromolecular diffusion

NASA Astrophysics Data System (ADS)

Hough, Loren; Stefferson, Michael; Norris, Samantha; Maguire, Laura; Vernerey, Franck; Betterton, Meredith

The diffusion of macromolecules is modified in crowded environments by both inert obstacles and interaction sites. Molecules are generally slowed in their movement inducing transient anomalous subdiffusion. Obstacles also modify the kinetics and equilibrium behavior of interaction between mobile proteins. In some biophysical contexts, bound molecules can still experience mobility, for example transcription factors sliding along DNA, membrane proteins with some entry and diffusion within lipid domains, or proteins that can enter into non-membrane bound compartments such as the nucleolus. We used lattice and continuum models to study the diffusive behavior of tracer particles which bind to obstacles and can diffuse within them. We show that binding significantly alters the motion of tracers. The type and degree of motion while bound is a key determinant of the tracer mobility. Our work has implications for protein-protein movement and interactions within living cells, including those involving intrinsically disordered proteins.

The Signal Transducer NPH3 Integrates the Phototropin1 Photosensor with PIN2-Based Polar Auxin Transport in Arabidopsis Root Phototropism[C][W

PubMed Central

Wan, Yinglang; Jasik, Jan; Wang, Li; Hao, Huaiqing; Volkmann, Dieter; Menzel, Diedrik; Mancuso, Stefano; Baluška, František; Lin, Jinxing

2012-01-01

Under blue light (BL) illumination, Arabidopsis thaliana roots grow away from the light source, showing a negative phototropic response. However, the mechanism of root phototropism is still unclear. Using a noninvasive microelectrode system, we showed that the BL sensor phototropin1 (phot1), the signal transducer NONPHOTOTROPIC HYPOCOTYL3 (NPH3), and the auxin efflux transporter PIN2 were essential for BL-induced auxin flux in the root apex transition zone. We also found that PIN2-green fluorescent protein (GFP) localized to vacuole-like compartments (VLCs) in dark-grown root epidermal and cortical cells, and phot1/NPH3 mediated a BL-initiated pathway that caused PIN2 redistribution to the plasma membrane. When dark-grown roots were exposed to brefeldin A (BFA), PIN2-GFP remained in VLCs in darkness, and BL caused PIN2-GFP disappearance from VLCs and induced PIN2-GFP-FM4-64 colocalization within enlarged compartments. In the nph3 mutant, both dark and BL BFA treatments caused the disappearance of PIN2-GFP from VLCs. However, in the phot1 mutant, PIN2-GFP remained within VLCs under both dark and BL BFA treatments, suggesting that phot1 and NPH3 play different roles in PIN2 localization. In conclusion, BL-induced root phototropism is based on the phot1/NPH3 signaling pathway, which stimulates the shootward auxin flux by modifying the subcellular targeting of PIN2 in the root apex transition zone. PMID:22374399

Intracellular Localization of Arabidopsis Sulfurtransferases1

PubMed Central

Bauer, Michael; Dietrich, Christof; Nowak, Katharina; Sierralta, Walter D.; Papenbrock, Jutta

2004-01-01

Sulfurtransferases (Str) comprise a group of enzymes widely distributed in archaea, eubacteria, and eukaryota which catalyze the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors. In all organisms analyzed to date, small gene families encoding Str proteins have been identified. The gene products were localized to different compartments of the cells. Our interest concerns the localization of Str proteins encoded in the nuclear genome of Arabidopsis. Computer-based prediction methods revealed localization in different compartments of the cell for six putative AtStrs. Several methods were used to determine the localization of the AtStr proteins experimentally. For AtStr1, a mitochondrial localization was demonstrated by immunodetection in the proteome of isolated mitochondria resolved by one- and two-dimensional gel electrophoresis and subsequent blotting. The respective mature AtStr1 protein was identified by mass spectrometry sequencing. The same result was obtained by transient expression of fusion constructs with the green fluorescent protein in Arabidopsis protoplasts, whereas AtStr2 was exclusively localized to the cytoplasm by this method. Three members of the single-domain AtStr were localized in the chloroplasts as demonstrated by transient expression of green fluorescent protein fusions in protoplasts and stomata, whereas the single-domain AtStr18 was shown to be cytoplasmic. The remarkable subcellular distribution of AtStr15 was additionally analyzed by transmission electron immunomicroscopy using a monospecific antibody against green fluorescent protein, indicating an attachment to the thylakoid membrane. The knowledge of the intracellular localization of the members of this multiprotein family will help elucidate their specific functions in the organism. PMID:15181206

Intracellular localization of Arabidopsis sulfurtransferases.

PubMed

Bauer, Michael; Dietrich, Christof; Nowak, Katharina; Sierralta, Walter D; Papenbrock, Jutta

2004-06-01

Sulfurtransferases (Str) comprise a group of enzymes widely distributed in archaea, eubacteria, and eukaryota which catalyze the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors. In all organisms analyzed to date, small gene families encoding Str proteins have been identified. The gene products were localized to different compartments of the cells. Our interest concerns the localization of Str proteins encoded in the nuclear genome of Arabidopsis. Computer-based prediction methods revealed localization in different compartments of the cell for six putative AtStrs. Several methods were used to determine the localization of the AtStr proteins experimentally. For AtStr1, a mitochondrial localization was demonstrated by immunodetection in the proteome of isolated mitochondria resolved by one- and two-dimensional gel electrophoresis and subsequent blotting. The respective mature AtStr1 protein was identified by mass spectrometry sequencing. The same result was obtained by transient expression of fusion constructs with the green fluorescent protein in Arabidopsis protoplasts, whereas AtStr2 was exclusively localized to the cytoplasm by this method. Three members of the single-domain AtStr were localized in the chloroplasts as demonstrated by transient expression of green fluorescent protein fusions in protoplasts and stomata, whereas the single-domain AtStr18 was shown to be cytoplasmic. The remarkable subcellular distribution of AtStr15 was additionally analyzed by transmission electron immunomicroscopy using a monospecific antibody against green fluorescent protein, indicating an attachment to the thylakoid membrane. The knowledge of the intracellular localization of the members of this multiprotein family will help elucidate their specific functions in the organism.

Spitzenkörper Localization and Intracellular Traffic of Green Fluorescent Protein-Labeled CHS-3 and CHS-6 Chitin Synthases in Living Hyphae of Neurospora crassa▿ †

PubMed Central

Riquelme, Meritxell; Bartnicki-García, Salomon; González-Prieto, Juan Manuel; Sánchez-León, Eddy; Verdín-Ramos, Jorge A.; Beltrán-Aguilar, Alejandro; Freitag, Michael

2007-01-01

The subcellular location and traffic of two selected chitin synthases (CHS) from Neurospora crassa, CHS-3 and CHS-6, labeled with green fluorescent protein (GFP), were studied by high-resolution confocal laser scanning microscopy. While we found some differences in the overall distribution patterns and appearances of CHS-3-GFP and CHS-6-GFP, most features were similar and were observed consistently. At the hyphal apex, fluorescence congregated into a conspicuous single body corresponding to the location of the Spitzenkörper (Spk). In distal regions (beyond 40 μm from the apex), CHS-GFP revealed a network of large endomembranous compartments that was predominantly comprised of irregular tubular shapes, while some compartments were distinctly spherical. In the distal subapex (20 to 40 μm from the apex), fluorescence was observed in globular bodies that appeared to disintegrate into vesicles as they advanced forward until reaching the proximal subapex (5 to 20 μm from the apex). CHS-GFP was also conspicuously found delineating developing septa. Analysis of fluorescence recovery after photobleaching suggested that the fluorescence of the Spk originated from the advancing population of microvesicles (chitosomes) in the subapex. The inability of brefeldin A to interfere with the traffic of CHS-containing microvesicles and the lack of colocalization of CHS-GFP with the endoplasmic reticulum (ER)-Golgi body fluorescent dyes lend support to the idea that CHS proteins are delivered to the cell surface via an alternative route distinct from the classical ER-Golgi body secretory pathway. PMID:17644657

Hsp70 Isoforms Are Essential for the Formation of Kaposi’s Sarcoma-Associated Herpesvirus Replication and Transcription Compartments

PubMed Central

Baquero-Pérez, Belinda; Whitehouse, Adrian

2015-01-01

Kaposi’s sarcoma-associated herpesvirus (KSHV) is an oncogenic herpesvirus associated with various AIDS-related malignancies. Like other herpesviruses, multiple processes required for KSHV lytic replication, including viral transcription, viral DNA synthesis and capsid assembly occur in virus-induced intranuclear structures, termed replication and transcription compartments (RTCs). Here we utilised a novel methodology, combining subcellular fractionation and quantitative proteomics, to identify cellular proteins which are recruited to KSHV-induced RTCs and thus play a key role in KSHV lytic replication. We show that several isoforms of the HSP70 chaperone family, Hsc70 and iHsp70, are redistributed from the cytoplasm into the nucleus coinciding with the initial formation of KSHV-induced RTCs. We demonstrate that nuclear chaperone foci are dynamic, initially forming adjacent to newly formed KSHV RTCs, however during later time points the chaperones move within KSHV RTCs and completely co-localise with actively replicating viral DNA. The functional significance of Hsp70 isoforms recruitment into KSHV RTCs was also examined using the specific Hsp70 isoform small molecule inhibitor, VER-155008. Intriguingly, results highlight an essential role of Hsp70 isoforms in the KSHV replication cycle independent of protein stability and maturation. Notably, inhibition of Hsp70 isoforms precluded KSHV RTC formation and RNA polymerase II (RNAPII) relocalisation to the viral genome leading to the abolishment of global KSHV transcription and subsequent viral protein synthesis and DNA replication. These new findings have revealed novel mechanisms that regulate KSHV lytic replication and highlight the potential of HSP70 inhibitors as novel antiviral agents. PMID:26587836

Detection of membrane protein-protein interaction in planta based on dual-intein-coupled tripartite split-GFP association.

PubMed

Liu, Tzu-Yin; Chou, Wen-Chun; Chen, Wei-Yuan; Chu, Ching-Yi; Dai, Chen-Yi; Wu, Pei-Yu

2018-05-01

Despite the great interest in identifying protein-protein interactions (PPIs) in biological systems, only a few attempts have been made at large-scale PPI screening in planta. Unlike biochemical assays, bimolecular fluorescence complementation allows visualization of transient and weak PPIs in vivo at subcellular resolution. However, when the non-fluorescent fragments are highly expressed, spontaneous and irreversible self-assembly of the split halves can easily generate false positives. The recently developed tripartite split-GFP system was shown to be a reliable PPI reporter in mammalian and yeast cells. In this study, we adapted this methodology, in combination with the β-estradiol-inducible expression cassette, for the detection of membrane PPIs in planta. Using a transient expression assay by agroinfiltration of Nicotiana benthamiana leaves, we demonstrate the utility of the tripartite split-GFP association in plant cells and affirm that the tripartite split-GFP system yields no spurious background signal even with abundant fusion proteins readily accessible to the compartments of interaction. By validating a few of the Arabidopsis PPIs, including the membrane PPIs implicated in phosphate homeostasis, we proved the fidelity of this assay for detection of PPIs in various cellular compartments in planta. Moreover, the technique combining the tripartite split-GFP association and dual-intein-mediated cleavage of polyprotein precursor is feasible in stably transformed Arabidopsis plants. Our results provide a proof-of-concept implementation of the tripartite split-GFP system as a potential tool for membrane PPI screens in planta. © 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Ltd.

Compartment-specific transcriptomics in a reef-building coral exposed to elevated temperatures.

PubMed

Mayfield, Anderson B; Wang, Yu-Bin; Chen, Chii-Shiarng; Lin, Chung-Yen; Chen, Shu-Hwa

2014-12-01

Although rising ocean temperatures threaten scleractinian corals and the reefs they construct, certain reef corals can acclimate to elevated temperatures to which they are rarely exposed in situ. Specimens of the model Indo-Pacific reef coral Pocillopora damicornis collected from upwelling reefs of Southern Taiwan were previously found to have survived a 36-week exposure to 30°C, a temperature they encounter infrequently and one that can elicit the breakdown of the coral-dinoflagellate (genus Symbiodinium) endosymbiosis in many corals of the Pacific Ocean. To gain insight into the subcellular pathways utilized by both the coral hosts and their mutualistic Symbiodinium populations to acclimate to this temperature, mRNAs from both control (27°C) and high (30°C)-temperature samples were sequenced on an Illumina platform and assembled into a 236 435-contig transcriptome. These P. damicornis specimens were found to be ~60% anthozoan and 40% microbe (Symbiodinium, other eukaryotic microbes, and bacteria), from an mRNA-perspective. Furthermore, a significantly higher proportion of genes from the Symbiodinium compartment were differentially expressed after two weeks of exposure. Specifically, at elevated temperatures, Symbiodinium populations residing within the coral gastrodermal tissues were more likely to up-regulate the expression of genes encoding proteins involved in metabolism than their coral hosts. Collectively, these transcriptome-scale data suggest that the two members of this endosymbiosis have distinct strategies for acclimating to elevated temperatures that are expected to characterize many of Earth's coral reefs in the coming decades. © 2014 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Electron spin resonance studies of the ovary of the rat

NASA Astrophysics Data System (ADS)

Andersen, Roy S.; Curtis, Joseph C.

1988-11-01

Electron spin resonance spectra of rat ovaries, isolated ovarian compartments, and ovarian subcellular fractions were compared with spectra of rat adrenals. Rat ovaries were found to exhibit ESR signals similar to those previously described in studies of mammalian adrenal and testis. Observations were made at 113 K in an anaerobic environment. ESR signals of the low-spin ferric cytochrome P-450, the non-heme protein ferredoxin, and the non-heme glycoprotein transferrin were consistently observed in whole ovaries. The first two signals were detected in mitochondrial fractions isolated from ovaries, while only cytochrome P-450 was detected in microsomal fractions. Signals from ferredoxin and cytochrome P-450 were also consistently observed in both whole adrenals and adrenal mitochondrial fractions. However, in the microsomal fraction only cytochrome P-450 was present. The g values for the cytochrome P-450 and ferredoxin signals found in this study of ovaries were identical to those previously reported and also found in this study in spectra of rat adrenals. The concentration of ferredoxin per milligram wet mass in rat ovaries appears to be only one-sixth of that in the rat adrenal. The concentration of cytochrome P-450 appears to be only one-ninth of that in the adrenal. Signals from ferredoxin were detected in all ovarian compartments except granulosa cells isolated from Graafian follicles. The third signal, that of transferrin, while often observed in the spectra of whole ovaries, has been attributed to residual blood in the tissues examined. The effects of oxygen on these spectra has been found to be considerable and is discussed.

In vivo engineering of bone tissues with hematopoietic functions and mixed chimerism

PubMed Central

Shih, Yu-Ru; Kang, Heemin; Rao, Vikram; Chiu, Yu-Jui; Kwon, Seong Keun; Varghese, Shyni

2017-01-01

Synthetic biomimetic matrices with osteoconductivity and osteoinductivity have been developed to regenerate bone tissues. However, whether such systems harbor donor marrow in vivo and support mixed chimerism remains unknown. We devised a strategy to engineer bone tissues with a functional bone marrow (BM) compartment in vivo by using a synthetic biomaterial with spatially differing cues. Specifically, we have developed a synthetic matrix recapitulating the dual-compartment structures by modular assembly of mineralized and nonmineralized macroporous structures. Our results show that these matrices incorporated with BM cells or BM flush transplanted into recipient mice matured into functional bone displaying the cardinal features of both skeletal and hematopoietic compartments similar to native bone tissue. The hematopoietic function of bone tissues was demonstrated by its support for a higher percentage of mixed chimerism compared with i.v. injection and donor hematopoietic cell mobilization in the circulation of nonirradiated recipients. Furthermore, hematopoietic cells sorted from the engineered bone tissues reconstituted the hematopoietic system when transplanted into lethally irradiated secondary recipients. Such engineered bone tissues could potentially be used as ectopic BM surrogates for treatment of nonmalignant BM diseases and as a tool to study hematopoiesis, donor–host cell dynamics, tumor tropism, and hematopoietic cell transplantation. PMID:28484009

In vivo engineering of bone tissues with hematopoietic functions and mixed chimerism.

PubMed

Shih, Yu-Ru; Kang, Heemin; Rao, Vikram; Chiu, Yu-Jui; Kwon, Seong Keun; Varghese, Shyni

2017-05-23

Synthetic biomimetic matrices with osteoconductivity and osteoinductivity have been developed to regenerate bone tissues. However, whether such systems harbor donor marrow in vivo and support mixed chimerism remains unknown. We devised a strategy to engineer bone tissues with a functional bone marrow (BM) compartment in vivo by using a synthetic biomaterial with spatially differing cues. Specifically, we have developed a synthetic matrix recapitulating the dual-compartment structures by modular assembly of mineralized and nonmineralized macroporous structures. Our results show that these matrices incorporated with BM cells or BM flush transplanted into recipient mice matured into functional bone displaying the cardinal features of both skeletal and hematopoietic compartments similar to native bone tissue. The hematopoietic function of bone tissues was demonstrated by its support for a higher percentage of mixed chimerism compared with i.v. injection and donor hematopoietic cell mobilization in the circulation of nonirradiated recipients. Furthermore, hematopoietic cells sorted from the engineered bone tissues reconstituted the hematopoietic system when transplanted into lethally irradiated secondary recipients. Such engineered bone tissues could potentially be used as ectopic BM surrogates for treatment of nonmalignant BM diseases and as a tool to study hematopoiesis, donor-host cell dynamics, tumor tropism, and hematopoietic cell transplantation.

Release and transport of mobile organic matter and biocolloids: A combined physicochemical and microbiological study

NASA Astrophysics Data System (ADS)

Reichel, Katharina; Schaefer, Sabine; Babin, Doreen; Smalla, Konny; Totsche, Kai Uwe

2016-04-01

Biogeochemical interfaces within the aggregate system of soils are "hot spots" of microbial activity and turnover of organic matter. We explore turnover, release and transport of mobile organic matter (MOM), micro-organisms (bio-colloids) and organo-mineral associations using a novel experimental approach employing two-layer columns experiment with matured soil under unsaturated flow conditions. The top layer was spiked with phenanthrene as a tracer for studying the decomposer communities involved in the decomposition of aromatic compounds that derive from lignin in natural systems. Columns were irrigated with artificial rain water with several flow interrupts of different durations. Physicochemical and chemical parameters as well as the microbial community composition were analysed in effluent samples and in soil slices. Release of MOM from the columns was in general controlled by non-equilibrium. Export of total and dissolved organic matter differed significantly in response to the flow interrupts. Effluent comprised organic and organo-mineral components as well as vital competent cells. By molecular biological methods we were even able to show that bacterial consortia exported are rather divers. Depth distribution of the bacterial communities associated with the immobile solid phase indicated high similarities in bacterial communities of the different depth layers and treatments. According to phenanthrene high affinity to the immobile phases, only a small fraction was subject to downstream transport with a strong decrease of the amount residing at the solid phase Our experiments directly prove that intact and competent microorganisms and even communities can be transported under unsaturated flow conditions. Moreover, we found that the dominant carbon source will impact not only the activity of specific microbial taxa but also their mobilization and transport. While total contribution of microbial organism to the mobile organic matter pool seems to be small, the fact that microbes will be mobilized and passively transported to downstream compartments helps to understand the processes that result in the inhabitation of pristine surfaces, thereby resulting in the establishment biogeochemical interfaces and initiation of aggregation in downstream compartments in the vadose zone.

Functional Characterization of the Human Mariner Transposon Hsmar2

PubMed Central

Gil, Estel; Bosch, Assumpcio; Lampe, David; Lizcano, Jose M.; Perales, Jose C.; Danos, Olivier; Chillon, Miguel

2013-01-01

DNA transposons are mobile elements with the ability to mobilize and transport genetic information between different chromosomal loci. Unfortunately, most transposons copies are currently inactivated, little is known about mariner elements in humans despite their role in the evolution of the human genome, even though the Hsmar2 transposon is associated to hotspots for homologous recombination involved in human genetic disorders as Charcot–Marie–Tooth, Prader-Willi/Angelman, and Williams syndromes. This manuscript describes the functional characterization of the human HSMAR2 transposase generated from fossil sequences and shows that the native HSMAR2 is active in human cells, but also in bacteria, with an efficiency similar to other mariner elements. We observe that the sub-cellular localization of HSMAR2 is dependent on the host cell type, and is cytotoxic when overexpressed in HeLa cells. Finally, we also demonstrate that the binding of HSMAR2 to its own ITRs is specific, and that the excision reaction leaves non-canonical footprints both in bacteria and eukaryotic cells. PMID:24039890

The effects of brefeldin-A on the high mannose oligosaccharides of mouse thyrotropin, free alpha-subunits, and total glycoproteins.

PubMed

Perkel, V S; Liu, A Y; Miura, Y; Magner, J A

1988-07-01

We have studied the effects of Brefeldin-A (BFA) on the processing of high mannose (Man) oligosaccharides of TSH. BFA is a drug that inhibits the intracellular translocation of newly synthesized glycoproteins and causes dilatation of the rough endoplasmic reticulum (RER) as well as mild swelling of the Golgi apparatus. Mouse pituitary thyrotropic tumor tissue was incubated with [3H]Man for a 2-h pulse, with and without a 3-h chase; BFA (5 micrograms/ml) was included during selected pulse and selected chase incubations. TSH and free alpha-subunits were obtained from detergent lysates of tissue by immunoprecipitation using specific antisera. Total glycoproteins were obtained by trichloroacetic acid precipitation. Endoglycosidase-H-released [3H]oligosaccharides were analyzed by paper chromatography. BFA inhibited carbohydrate processing of TSH, free alpha-subunits, and total glycoproteins, resulting in the accumulation of Man8GlcNAc2, Man7GlcNAc2, Man6GlcNAc2, and Man5GlcNAc2, especially during the chase period. Subcellular fractions enriched in RER, heavy (proximal) Golgi, and light (distal) Golgi were prepared by centrifugation in discontinuous sucrose gradients. [3H]Man-labeled oligosaccharides of TSH and total glycoproteins in the subcellular fractions were analyzed. In contrast to oligosaccharides with eight or nine Man residues found in control incubations, BFA caused the accumulation of oligosaccharides containing five to eight Man residues. These BFA-induced oligosaccharide alterations began in the RER and proximal Golgi with the 2-h pulse and extended into the distal Golgi during the chase incubations. Thus, BFA blocks the normal intracellular transport and processing of TSH, free alpha-subunits, and total glycoproteins within thyrotrophs, causing species with smaller than normal high Man oligosaccharides to appear in subcellular compartments as early as the RER. The translocation block between RER and Golgi produced by BFA may prevent the processing of Man8GlcNAc2 to Man5GlcNAc2 by Golgi (alpha,1-2)mannosidase I, yet the species retained within the RER may be subject to ongoing processing by endoplasmic reticulum (alpha,1-2)mannosidase, resulting in the accumulation of Man5-8GlcNAc2 within the RER.

Skylab

NASA Image and Video Library

1970-01-01

This photograph was taken during assembly of the bottom and upper floors of the Skylab Orbital Workshop (OWS). The OWS was divided into two major compartments. The lower level provided crew accommodations for sleeping, food preparation and consumption, hygiene, waste processing and disposal, and performance of certain experiments. The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment.

Novel therapeutic strategies to target leukemic cells that hijack compartmentalized continuous hematopoietic stem cell niches.

PubMed

Hira, Vashendriya V V; Van Noorden, Cornelis J F; Carraway, Hetty E; Maciejewski, Jaroslaw P; Molenaar, Remco J

2017-08-01

Acute myeloid leukemia and acute lymphoblastic leukemia cells hijack hematopoietic stem cell (HSC) niches in the bone marrow and become leukemic stem cells (LSCs) at the expense of normal HSCs. LSCs are quiescent and resistant to chemotherapy and can cause relapse of the disease. HSCs in niches are needed to generate blood cell precursors that are committed to unilineage differentiation and eventually production of mature blood cells, including red blood cells, megakaryocytes, myeloid cells and lymphocytes. Thus far, three types of HSC niches are recognized: endosteal, reticular and perivascular niches. However, we argue here that there is only one type of HSC niche, which consists of a periarteriolar compartment and a perisinusoidal compartment. In the periarteriolar compartment, hypoxia and low levels of reactive oxygen species preserve the HSC pool. In the perisinusoidal compartment, hypoxia in combination with higher levels of reactive oxygen species enables proliferation of progenitor cells and their mobilization into the circulation. Because HSC niches offer protection to LSCs against chemotherapy, we review novel therapeutic strategies to inhibit homing of LSCs in niches for the prevention of dedifferentiation of leukemic cells into LSCs and to stimulate migration of leukemic cells out of niches. These strategies enhance differentiation and proliferation and thus sensitize leukemic cells to chemotherapy. Finally, we list clinical trials of therapies that tackle LSCs in HSC niches to circumvent their protection against chemotherapy. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Skylab

NASA Image and Video Library

1972-01-01

This cutaway illustration shows the characteristics and basic elements of the Skylab Orbiter Workshop (OWS). The OWS was divided into two major compartments. The lower level provided crew accommodations for sleeping, food preparation and consumption, hygiene, waste processing and disposal, and performance of certain experiments. The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment. The compartment below the crew quarters was a container for liquid and solid waste and trash accumulated throughout the mission. A solar array, consisting of two wings covered on one side with solar cells, was mounted outside the workshop to generate electrical power to augment the power generated by another solar array mounted on the solar observatory. Thrusters were provided at one end of the workshop for short-term control of the attitude of the space station.

Skylab Orbiter Workshop Illustration

NASA Technical Reports Server (NTRS)

1972-01-01

This cutaway illustration shows the characteristics and basic elements of the Skylab Orbiter Workshop (OWS). The OWS was divided into two major compartments. The lower level provided crew accommodations for sleeping, food preparation and consumption, hygiene, waste processing and disposal, and performance of certain experiments. The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment. The compartment below the crew quarters was a container for liquid and solid waste and trash accumulated throughout the mission. A solar array, consisting of two wings covered on one side with solar cells, was mounted outside the workshop to generate electrical power to augment the power generated by another solar array mounted on the solar observatory. Thrusters were provided at one end of the workshop for short-term control of the attitude of the space station.

Cutaway View of Skylab Orbital Workshop

NASA Technical Reports Server (NTRS)

1972-01-01

This illustration is a cutaway view of the Orbital Workshop (OWS) showing details of the living and working quarters. The OWS was divided into two major compartments. The lower level provided crew accommodations for sleeping, food preparation and consumption, hygiene, waste processing and disposal, and performance of certain experiments. The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment . The compartment below the crew quarters was a container for liquid and solid waste and trash accumulated throughout the mission. A solar array, consisting of two wings covered on one side with solar cells, was mounted outside the workshop to generate electrical power to augment the power generated by another solar array mounted on the solar observatory. Thrusters were provided at one end of the workshop for short-term control of the attitude of the space station.

A Molecular Smart Surface for Spatio-Temporal Studies of Cell Mobility

PubMed Central

Lee, Eun-ju; Luo, Wei; Chan, Eugene W. L.; Yousaf, Muhammad N.

2015-01-01

Active migration in both healthy and malignant cells requires the integration of information derived from soluble signaling molecules with positional information gained from interactions with the extracellular matrix and with other cells. How a cell responds and moves involves complex signaling cascades that guide the directional functions of the cytoskeleton as well as the synthesis and release of proteases that facilitate movement through tissues. The biochemical events of the signaling cascades occur in a spatially and temporally coordinated manner then dynamically shape the cytoskeleton in specific subcellular regions. Therefore, cell migration and invasion involve a precise but constantly changing subcellular nano-architecture. A multidisciplinary effort that combines new surface chemistry and cell biological tools is required to understand the reorganization of cytoskeleton triggered by complex signaling during migration. Here we generate a class of model substrates that modulate the dynamic environment for a variety of cell adhesion and migration experiments. In particular, we use these dynamic substrates to probe in real-time how the interplay between the population of cells, the initial pattern geometry, ligand density, ligand affinity and integrin composition affects cell migration and growth. Whole genome microarray analysis indicates that several classes of genes ranging from signal transduction to cytoskeletal reorganization are differentially regulated depending on the nature of the surface conditions. PMID:26030281

Pb2+ ions mobility perturbation by iron particles during electrokinetic remediation of contaminated soil.

PubMed

Zulfiqar, Waqas; Iqbal, Muhammad Asad; Butt, Mehwish Khalid

2017-02-01

Electrokinetic (EK) remediation is one of the most useful approaches for de-contamination of soils. However, it is unclear that how and when the electrokinetic remediation gives advantages over other remediation techniques in soil. This study was designed to find the influence of Fe 2+ particles on the mobility of Pb 2+ ions, during electrokinetic remediation, in soil contaminated purposely by lead nitrate Pb(NO 3 ) 2 . Two types of electrokinetic experiments were performed, by using iron and graphite electrodes. The Fe 2+ ions from the iron electrodes, produced due to acidic environment in anode compartment, affected the mobility of lead particles by precipitating as Fe(OH) 2 . Fe 2+ ions enhance the adsorption of lead ions in soil. The results show Fe 2+ ions of lower ionic conductivity decreased mobility of other particles in soil. Electrokinetic remediation for up to 120 h with iron electrodes is shown to be less effective for removal of lead. In contrast, graphite electrodes were 15 times more effective in lead removal from soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Protein Mobilization in Germinating Mung Bean Seeds Involves Vacuolar Sorting Receptors and Multivesicular Bodies1[W][OA

PubMed Central

Wang, Junqi; Li, Yubing; Lo, Sze Wan; Hillmer, Stefan; Sun, Samuel S.M.; Robinson, David G.; Jiang, Liwen

2007-01-01

Plants accumulate and store proteins in protein storage vacuoles (PSVs) during seed development and maturation. Upon seed germination, these storage proteins are mobilized to provide nutrients for seedling growth. However, little is known about the molecular mechanisms of protein degradation during seed germination. Here we test the hypothesis that vacuolar sorting receptor (VSR) proteins play a role in mediating protein degradation in germinating seeds. We demonstrate that both VSR proteins and hydrolytic enzymes are synthesized de novo during mung bean (Vigna radiata) seed germination. Immunogold electron microscopy with VSR antibodies demonstrate that VSRs mainly locate to the peripheral membrane of multivesicular bodies (MVBs), presumably as recycling receptors in day 1 germinating seeds, but become internalized to the MVB lumen, presumably for degradation at day 3 germination. Chemical cross-linking and immunoprecipitation with VSR antibodies have identified the cysteine protease aleurain as a specific VSR-interacting protein in germinating seeds. Further confocal immunofluorescence and immunogold electron microscopy studies demonstrate that VSR and aleurain colocalize to MVBs as well as PSVs in germinating seeds. Thus, MVBs in germinating seeds exercise dual functions: as a storage compartment for proteases that are physically separated from PSVs in the mature seed and as an intermediate compartment for VSR-mediated delivery of proteases from the Golgi apparatus to the PSV for protein degradation during seed germination. PMID:17322331

Optimization of immunostaining on flat-mounted human corneas.

PubMed

Forest, Fabien; Thuret, Gilles; Gain, Philippe; Dumollard, Jean-Marc; Peoc'h, Michel; Perrache, Chantal; He, Zhiguo

2015-01-01

In the literature, immunohistochemistry on cross sections is the main technique used to study protein expression in corneal endothelial cells (ECs), even though this method allows visualization of few ECs, without clear subcellular localization, and is subject to the staining artifacts frequently encountered at tissue borders. We previously proposed several protocols, using fixation in 0.5% paraformaldehyde (PFA) or in methanol, allowing immunostaining on flatmounted corneas for proteins of different cell compartments. In the present study, we further refined the technique by systematically assessing the effect of fixative temperature. Last, we used optimized protocols to further demonstrate the considerable advantages of immunostaining on flatmounted intact corneas: detection of rare cells in large fields of thousands of ECs and epithelial cells, and accurate subcellular localization of given proteins. The staining of four ubiquitous proteins, ZO-1, hnRNP L, actin, and histone H3, with clearly different subcellular localizations, was analyzed in ECs of organ-cultured corneas. Whole intact human corneas were fixed for 30 min in 0.5% paraformaldehyde or pure methanol at four temperatures (4 °C for PFA, -20 °C for methanol, and 23, 37, and 50 °C for both). Experiments were performed in duplicate and repeated on three corneas. Standardized pictures were analyzed independently by two experts. Second, optimized immunostaining protocols were applied to fresh corneas for three applications: identification of rare cells that express KI67 in the endothelium of specimens with Fuch's endothelial corneal dystrophy (FECD), the precise localization of neural cell adhesion molecules (NCAMs) in normal ECs and of the cytokeratin pair K3/12 and CD44 in normal epithelial cells, and the identification of cells that express S100b in the normal epithelium. Temperature strongly influenced immunostaining quality. There was no ubiquitous protocol, but nevertheless, room temperature may be recommended as first-line temperature during fixation, instead of the conventional -20 °C for methanol and 4 °C for PFA. Further optimization may be required for certain target proteins. Optimized protocols allowed description of two previously unknown findings: the presence of a few proliferating ECs in FECD specimens, suggesting ineffective compensatory mechanisms against premature EC death, and the localization of NCAMs exclusively in the lateral membranes of ECs, showing hexagonal organization at the apical pole and an irregular shape with increasing complexity toward the basal pole. Optimized protocols were also effective for the epithelium, allowing clear localization of cytokeratin 3/12 and CD44 in superficial and basal epithelial cells, respectively. Finally, S100b allowed identification of clusters of epithelial Langerhans cells near the limbus and more centrally. Fixative temperature is a crucial parameter in optimizing immunostaining on flatmounted intact corneas. Whole-tissue overview and precise subcellular staining are significant advantages over conventional immunohistochemistry (IHC) on cross sections. This technique, initially developed for the corneal endothelium, proved equally suitable for the corneal epithelium and could be used for other superficial mono- and multilayered epithelia.

Reactive oxygen species mediate growth and death in submerged plants

PubMed Central

Steffens, Bianka; Steffen-Heins, Anja; Sauter, Margret

2013-01-01

Aquatic and semi-aquatic plants are well adapted to survive partial or complete submergence which is commonly accompanied by oxygen deprivation. The gaseous hormone ethylene controls a number of adaptive responses to submergence including adventitious root growth and aerenchyma formation. Reactive oxygen species (ROS) act as signaling intermediates in ethylene-controlled submergence adaptation and possibly also independent of ethylene. ROS levels are controlled by synthesis, enzymatic metabolism, and non-enzymatic scavenging. While the actors are by and large known, we still have to learn about altered ROS at the subcellular level and how they are brought about, and the signaling cascades that trigger a specific response. This review briefly summarizes our knowledge on the contribution of ROS to submergence adaptation and describes spectrophotometrical, histochemical, and live cell imaging detection methods that have been used to study changes in ROS abundance. Electron paramagnetic resonance (EPR) spectroscopy is introduced as a method that allows identification and quantification of specific ROS in cell compartments. The use of advanced technologies such as EPR spectroscopy will be necessary to untangle the intricate and partially interwoven signaling networks of ethylene and ROS. PMID:23761805