scholarly journals 14-3-3γ-mediated transport of plakoglobin to the cell border is required for the initiation of desmosome assemblyin vitroandin vivo

2014 ◽  
Vol 127 (10) ◽  
pp. 2174-2188 ◽  
Author(s):  
Lalit Sehgal ◽  
Amitabha Mukhopadhyay ◽  
Anandi Rajan ◽  
Nileema Khapare ◽  
Mugdha Sawant ◽  
...  
Keyword(s):  
Cell Border

The location and mechanism of hyperosmotic fluid secretion in the rectum of the saline-water mosquito larvae Aedes taeniorhynchus

1977 ◽  
Vol 66 (1) ◽  
pp. 111-126
Author(s):  
T. J. Bradley ◽  
J. E. Phillips
Keyword(s):  
Saline Water ◽  
Fluid Secretion ◽  
Opposite Polarity ◽  
Posterior Segment ◽  
Transport Processes ◽  
Cell Border ◽  
Experimental Conditions ◽  
Ultrastructural Studies ◽  
Aedes Taeniorhynchus

1. Ligation between the anterior and posterior segments of the rectum in vitro was used to demonstrate that the posterior rectum is the site of hyperosmotic secretion to the lumen side. Observations were consistent with a reabsorptive function for the anterior rectum. These results support predictions from ultrastructural studies of these two segments. 2. The initial potential of the rectal lumen, relative to the haemocoel side, was of opposite polarity in the anterior (−10 mV) and posterior (+ 10 mV) segments and these values decreased to −2 and +6 mV respectively in ligated recta which had secreted for 2 h. 3. A comparison of these potential difference measurements with concentration differences developed across the rectal epithelium under the same experimental conditions indicates that Na+, K+, Mg2+, and Cl- are all actively transported by the posterior segment to the lumen side. 4. The influence of different haemolymph concentrations of Na+, K+, and Cl- on the potential differences across the basal cell border and across the whole rectal epithelium are reported. Based on this and previous data, we propose a model for the organization of transport processes within the single celltype present in the posterior rectal epithelium.

scholarly journals Uptake and intracellular fate of l-DOPA in a human intestinal epithelial cell line: Caco-2

1998 ◽  
Vol 275 (1) ◽  
pp. C104-C112 ◽  
Author(s):  
M. A. Vieira-Coelho ◽  
P. Soares-Da-Silva
Keyword(s):  
Apical Cell ◽  
Acid Decarboxylase ◽  
Epithelial Cell Line ◽  
Uptake System ◽  
Intestinal Epithelial ◽  
Cell Border ◽  
Amino Acid Decarboxylase ◽  
Dopa Concentration ◽  
Menten Constant ◽  
Cells Cultured

The aim of the present study was to examine the kinetic characteristics of thel-3,4-dihydroxyphenylalanine (l-DOPA) transporter and the fate of newly formed dopamine in Caco-2 cells. In the presence of 50 μM benserazide (an inhibitor of aromaticl-amino acid decarboxylase), l-DOPA was rapidly accumulated in Caco-2 cells. At equilibrium (30 min of incubation) the intracellular l-DOPA concentration was 10.2 ± 0.1 μM at a medium concentration of 0.5 μM. In saturation experiments the accumulation of l-DOPA was saturable with a Michaelis-Menten constant ( K m) of 60 ± 10 μM and a maximal reaction velocity ( V max) of 6.6 ± 0.3 nmol ⋅ mg protein−1 ⋅ 6 min−1; at 4°C the amount of l-DOPA accumulated in the cells was nonsaturable. When cells were incubated with increasing concentrations of l-DOPA (10–100 μM) in the absence of benserazide, a substantial amount of thel-DOPA that was taken up was decarboxylated to dopamine, with an apparent K m of 27.2 μM. In experiments performed in cells cultured in polycarbonate filters, the accumulation of l-DOPA in the presence of benserazide was greater when the substrate was applied from the basolateral cell border than when it was applied from the apical cell border. In the absence of benserazide, l-DOPA applied from the basolateral cell border resulted in a nonlinear formation of dopamine ( K m = 43 ± 7 μM, V max = 23.7 ± 1.2 nmol ⋅ mg protein−1 ⋅ 6 min−1). The amount of dopamine leaving the cell through the apical cell border was lower than the amount that escaped through the basolateral cell border, and the process was saturable ( K m = 623 ± 238 μM, V max = 0.19 ± 0.02 nmol ⋅ mg protein−1 ⋅ 6 min−1). In conclusion, the data presented here show that Caco-2 cells are endowed with an efficient l-DOPA uptake system, and intracellularl-DOPA was found to be rapidly converted to dopamine, some of which diffuses out of the cell. The utilization of Caco-2 cells cultured on polycarbonate filters probably provides a better way to look at processes such as the outward transfer of intracellular molecules, namely, the outward transfer of newly formed dopamine.

scholarly journals Alanine Efflux across the Serosal Border of Turtle Intestine

1972 ◽  
Vol 60 (6) ◽  
pp. 720-734 ◽  
Author(s):  
J.J. Hajjar ◽  
R.N. Khuri ◽  
Peter F. Curran
Keyword(s):  
Amino Acid ◽  
Intestinal Cells ◽  
Mucosal Cell ◽  
Transport Mechanisms ◽  
Acid Transport ◽  
Free Medium ◽  
Cell Border ◽  
Alanine Transport ◽  
Acid Extrusion ◽  
Amino Acid Flux

The exit of alanine across the serosal border of the epithelial cells of turtle intestine was measured by direct and indirect techniques. A decrease or an increase in cell Na did not affect the amino acid flux from cell to serosal solution. Cells loaded with Na and alanine did not exhibit any extrusion of alanine when their serosal membranes were exposed to an Na-free medium containing alanine. However, substantial amino acid extrusion was observed across the mucosal cell border under similar conditions. Although alanine flux across the serosal membrane appeared to be Na-independent, it showed a tendency toward saturation as cellular alanine concentration was elevated. The results are consistent with the postulate that the serosal and mucosal membranes of intestinal cells are asymmetrical with respect to amino acid transport mechanisms. The serosal membrane appears to have an Na-independent carrier-mediated mechanism responsible for alanine transport while transport across the mucosal border involves an Na-dependent process.

scholarly journals The characteristics of host lipid body biogenesis during coral-dinoflagellate endosymbiosis

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11652
Author(s):  
Hung-Kai Chen ◽  
Sabrina L. Rosset ◽  
Li-Hsueh Wang ◽  
Chii-Shiarng Chen
Keyword(s):  
Lipid Body ◽  
Solar Irradiation ◽  
Hermatypic Coral ◽  
Cellular Regulation ◽  
Tissue Layer ◽  
Cell Border ◽  
Intracellular Lipid ◽  
Metabolic Signaling ◽  
Abnormal Protein ◽  
Gastrodermal Cell

Intracellular lipid body (LB) biogenesis depends on the symbiosis between coral hosts and their Symbiodinaceae. Therefore, understanding the mechanism(s) behind LB biosynthesis in corals can portentially elucide the drivers of cellular regulation during endosymbiosis. This study assessed LB formation in the gastrodermal tissue layer of the hermatypic coral Euphyllia glabrescens. Diel rhythmicity in LB size and distribution was observed; solar irradiation onset at sunrise initiated an increase in LB formation, which continued throughout the day and peaked after sunset at 18:00. The LBs migrated from the area near the mesoglea to the gastrodermal cell border near the coelenteron. Micro-LB biogenesis occurred in the endoplasmic reticulum (ER) of the host gastrodermal cells. A transcriptomic analysis of genes related to lipogenesis indicated that binding immunoglobulin protein (BiP) plays a key role in metabolic signaling pathways. The diel rhythmicity of LB biogenesis was correlated with ER-localized BiP expression. BiP expression peaked during the period with the largest increase in LB formation, thereby indicating that the chaperoning reaction of abnormal protein folding inside the host ER is likely involved in LB biosynthesis. These findings suggest that the host ER, central to LB formation, potentially facilitates the regulation of endosymbiosis between coral hosts and Symbiodiniaceae.

Changes in the Pericardial Cells of Periplaneta Americana induced by Exposure to Homogenates of the Corpus Cardiacum

1962 ◽  
Vol s3-103 (63) ◽  
pp. 349-357
Author(s):  
K. G. DAVEY
Keyword(s):  
Periplaneta Americana ◽  
Prolonged Exposure ◽  
Active Material ◽  
Secretory Process ◽  
Corpus Cardiacum ◽  
Cell Border ◽  
Pericardial Cells ◽  
Pharmacologically Active

The pericardial cells of the cockroach, Periplaneta americana, undergo change associated with secretion when they are exposed to homogenates of the corpus cardiacum. The cells become markedly larger, and the nuclei send out branches as far as the cell border. Large secretory droplets appear as vacuoles first near the nucleus and later throughout the cytoplasm. Smaller vacuoles come to occupy the area near the periphery of the cell: these are considered to be the remains of the larger vacuoles after they have discharged their contents. Prolonged exposure of the cells to the homogenates in vitro leads to the cessation of these secretory activities, presumably as a result of the exhaustion of metabolites concerned in the secretory process. The cells also become more pronouncedly argentaffin as a result of exposure to the corpus cardiacum. These changes are considered in the light of the discovery that the pericardial cells produce a pharmacologically active material from an inert precursor in response to a secretion from the corpus cardiacum.

Memoirs: On the Nature of the Free Cell-Border of certain Mid-Gut Epithelia

1936 ◽  
Vol s2-79 (313) ◽  
pp. 123-150
Author(s):  
G. E. NEWELL ◽  
E. W. BAXTER
Keyword(s):  
Free Surface ◽  
Special Reference ◽  
Brush Border ◽  
Free Cell ◽  
Peritrophic Membrane ◽  
Middle Region ◽  
Cell Border ◽  
Similar Nature ◽  
Brush Borders ◽  
Motile Bacteria

1. The terms cilia, rod-border, brush-border, and other terms used in this paper are defined. 2. The epithelium lining the mid-gut of Melinna is described with special reference to the cell-border. Variation between different regions of the gut are noted. There are two main types of epithelia: (i) ciliated, (ii) rod-bordered. The presence of a peritrophic membrane in the middle region of the stomach is noted. 3. A description of the mid-gutepithelium of Locusta and Chironomus is given, and the essential similarity between the brush-borders of the two is stressed. 4. The ciliated effect described by Vignon in Chironomus is shown to be due to the presence of motile bacteria. 5. Prom a thorough survey of the literature and from our own observations, it is concluded that there are two main types of cell-borders: A. Motile, i.e. ciliated; with which basal corpuscles, derived from division of the centrosomes, are always associated. B. Non-motile.--It is held that these are of two distinct types: (i) Rod-border, where the elements are probably homologous with the basal segments of cilia. This type occurs in Melinna, Lumbricus, and probably in other animals, and it is possible that the striated free border found in the epithelium of the vertebrate intestine is of a somewhat similar nature. (ii) Brush-border, where the elements are simple filaments and bear no relation to cilia. This type is found typically in insects and in a slightly modified condition in the uriniferous tubules of vertebrates. Both motile and non-motile elements lie above the free surface of the cell which is marked by the limiting membrane. 6. Mention is made of the brush-border epithelium of the Malpighian tubiiles of insects.

Cell Border Demarcation in the Scanning Electron Microscope by Silver Stains

1974 ◽  
Vol 16 (1) ◽  
pp. 221-239
Author(s):  
W. C. DE BRUIJN ◽  
W. VAN MOURIK ◽  
I. J. BOSVELD
Keyword(s):  
Endothelial Cells ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Cell Surface ◽  
Silver Nitrate ◽  
Aortic Tissue ◽  
Cell Border ◽  
Thorium Dioxide ◽  
Dextran Solution ◽  
Scanning Electron

Silver nitrate and silver proteinate were both successfully used as electron stains for the demarcation of the aortic endothelial cell borders in the scanning electron microscope. By energy-dispersive X-ray analysis it was demonstrated that silver was present in the demarcation lines around the endothelial cells. The presence of silver closely coincided with the places where secondary electrons were produced. Judged by the quality of the aortic tissue in the transmission electron microscope, the method using silver proteinate was preferable to those using silver nitrate. The limited resolution of the method is demonstrated. The role of the dextran solution in such procedures was investigated, and it was shown that the presence of such a dextran solution, or its particle size or charge, does not contribute to the formation of these silver lines around the endothelial cells. In ultrathin sections of such material the cell surface-contrasting capacity of colloidal thorium dioxide solutions was compared to the cell border-contrasting capacity of silver proteinate. It was found that prior aldehyde fixation abolished the cell border demarcation by silver proteinate, but only reduced the cell surface demarcation by thorium dioxide particles.

Abstract 300: The Actin Cytoskeleton Confers Specificity of Cx43 Delivery to Intercalated Discs

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Shan-Shan Zhang ◽  
SoonGweon Hong ◽  
Luke P Lee ◽  
Robin M Shaw
Keyword(s):  
Connexin 43 ◽  
Single Particle Tracking ◽  
Cell Junction ◽  
Cell Border ◽  
Intercalated Discs ◽  
Biochemical Interaction ◽  
Junction Protein ◽  
Latrunculin A ◽  
Long Fibers ◽  
Cell Cell

Connexin 43 (Cx43) gap junctions (GJs) electrically couple ventricular cardiomyocytes at the intercalated disc (ID), orchestrating organized organ level contraction with each heartbeat. Disease-related disruption of the Cx43 cytoskeletal trafficking machinery is associated with mislocalization of the Cx43 gap junction protein away from the ID and lethal arrhythmias. We recently found that the majority of intracellular Cx43 cargo is associated with actin, not microtubules, and is either paused or moving slowly. It is not understood why actin is involved in Cx43 trafficking. Using micropatterned HeLa cell pairs and whole-cell automated single particle tracking algorithms, we detected that distinct actin polarity exists in the cell, including highly oriented long fibers associated with fast-moving Cx43 cargo aligned toward actively forming GJ plaques. F-actin disruption with latrunculin A (LatA) leads to a loss of Cx43 cargo directionality toward the cell-cell border, as well as a marked decrease in overall microtubule length. We also found a LatA-dependent biochemical interaction between β-actin and the microtubule plus-end-binding protein EB1, which leads growing microtubules and is a necessary component of the Cx43 forward trafficking machinery. In live cell pairs, F-actin disruption resulted in a decrease in overall EB1 activity and in the number of fully extended microtubules that reach the cell-cell border. Together, these results indicate that actin contributes to the specificity of Cx43 delivery by directing EB1-based microtubule growth toward the cell-cell junction (Please refer to attached diagram).

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