scholarly journals Induction of Terminal Differentiation in Epithelial Cells Requires Polymerization of Hensin by Galectin 3

2000 ◽  
Vol 151 (6) ◽  
pp. 1235-1246 ◽  
Author(s):  
Chinami Hikita ◽  
Soundarapandian Vijayakumar ◽  
Jiro Takito ◽  
Hediyet Erdjument-Bromage ◽  
Paul Tempst ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Terminal Differentiation ◽  
High Density ◽  
Seeding Density ◽  
Epithelial Cell Line ◽  
Low Density ◽  
Membrane Structures ◽  
Density State ◽  
Galectin 3

During terminal differentiation, epithelia become columnar and develop specialized apical membrane structures (microvilli) and functions (regulated endocytosis and exocytosis). Using a clonal intercalated epithelial cell line, we found that high seeding density induced these characteristics, whereas low density seeding maintained a protoepithelial state. When cells were plated at low density, but on the extracellular matrix of high density cells, they converted to the more differentiated phenotype. The extracellular matrix (ECM) protein responsible for this activity was purified and found to be a large 230-kD protein, which we termed hensin. High density seeding caused hensin to be polymerized and deposited in the extracellular matrix, and only this form of hensin was able to induce terminal differentiation. Antibodies to hensin blocked the change in phenotype. However, its purification to homogeneity resulted in loss of activity, suggesting that an additional protein might be necessary for induction of terminal differentiation. Here, we found that a 29-kD protein specifically associates with hensin in the ECM. Addition of purified p29 restored the activity of homogenously purified hensin. Mass fingerprinting identified p29 as galectin 3. Purified recombinant galectin 3 was able to bind to hensin and to polymerize it in vitro. Seeding cells at high density induced secretion of galectin 3 into the ECM where it bundled hensin. Hence, the high density state causes a secretion of a protein that acts on another ECM protein to allow the new complex to signal the cell to change its phenotype. This is a new mechanism of inside-out signaling.

scholarly journals X-ray studies of the transformation from high- to low-density amorphous water

2019 ◽  
Vol 377 (2146) ◽  
pp. 20180164 ◽  
Author(s):  
Daniel Mariedahl ◽  
Fivos Perakis ◽  
Alexander Späh ◽  
Harshad Pathak ◽  
Kyung Hwan Kim ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Structural Evolution ◽  
High Energy ◽  
Real Space ◽  
High Density ◽  
Low Density ◽  
X Ray ◽  
Amorphous Ice ◽  
Density State ◽  
Amorphous States

Here we report about the structural evolution during the conversion from high-density amorphous ices at ambient pressure to the low-density state. Using high-energy X-ray diffraction, we have monitored the transformation by following in reciprocal space the structure factor S OO ( Q ) and derived in real space the pair distribution function g OO ( r ). Heating equilibrated high-density amorphous ice (eHDA) at a fast rate (4 K min –1 ), the transition to the low-density form occurs very rapidly, while domains of both high- and low-density coexist. On the other hand, the transition in the case of unannealed HDA (uHDA) and very-high-density amorphous ice is more complex and of continuous nature. The direct comparison of eHDA and uHDA indicates that the molecular structure of uHDA contains a larger amount of tetrahedral motives. The different crystallization behaviour of the derived low-density amorphous states is interpreted as emanating from increased tetrahedral coordination present in uHDA. This article is part of the theme issue ‘The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets'.

scholarly journals Decreased in vivo survival of hydrogen peroxide-damaged baboon red blood cells

Blood ◽  
1990 ◽  
Vol 76 (1) ◽  
pp. 206-211 ◽  
Author(s):  
J McKenney ◽  
CR Valeri ◽  
N Mohandas ◽  
N Fortier ◽  
A Giorgio ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidant Stress ◽  
Membrane Damage ◽  
High Density ◽  
Low Density ◽  
Skeletal Changes ◽  
Sequence Of Events ◽  
Dose Dependent Fashion

Abstract In this study we attempt to establish the consequence of in vitro hydrogen peroxide (H2O2)-induced membrane damage as manifested by spectrin-hemoglobin (Sp-Hb) complex formation and decreased red blood cell (RBC) deformability to in vivo RBC survival in baboons. After exposure to 135 to 581 mumols/L H2O2 and reduction with dithiothreitol (DTE), baboon RBCs were infused into the animal, and the fraction of cells remaining in circulation after 24 hours and the lifespan of surviving cells were quantitated. In a dose-dependent fashion, a positive correlation was observed between in vitro membrane alterations and the 24-hour in vivo survival. While 12% of the control cells were removed from circulation in 24 hours, 23% were removed after treatment with 339 mumols/L H2O2, and 36% following exposure to 581 mumols/L H2O2. Pretreatment with carbon monoxide before exposure with H2O2 increased the survival of oxidized RBCs. RBCs not removed from circulation in the first 24 hours had a normal lifespan. Moreover, by selectively isolating biotin-labeled, peroxide-treated cells that survived the first 24-hour posttransfusion period, a significant decrease in Sp-Hb crosslinking was observed in these cells. These results suggest that a subpopulation of cells sensitive to oxidation were removed during the first 24 hours. To identify this population, the survival of density-fractionated RBCs exposed to oxidant stress was quantitated. No differences in either the 24-hour survival or RBC life span were observed between untreated low-density (MCHC less than or equal to 32g/dL) and high-density cells (MCHC greater than or equal to 37g/dL). However, striking differences were noted after treatment with 339 mumols/L H2O2, with the 24-hour survival of high-density cells showing a marked decrease compared with low-density cells. These data support our hypothesis that during peroxidative membrane damage, Hb oxidation initiates a sequence of events resulting in skeletal changes that lead to membrane alterations and, eventually, in vivo destruction, and that the dense, dehydrated cells are more susceptible to oxidant damage.

scholarly journals Monocyte Migration Driven by Galectin-3 Occurs through Distinct Mechanisms Involving Selective Interactions with the Extracellular Matrix

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Cláudia Danella Polli ◽  
Karina Alves Toledo ◽  
Luís Henrique Franco ◽  
Vânia Sammartino Mariano ◽  
Leandro Licursi de Oliveira ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Carbohydrate Binding ◽  
Binding Assays ◽  
Binding Ability ◽  
Monocyte Migration ◽  
Important Mediator ◽  
Galectin 3 ◽  
Transwell System ◽  
Selective Interactions

Monocyte migration into tissues, an important event in inflammation, requires an intricate interplay between determinants on cell surfaces and extracellular matrix (ECM). Galectin-3 is able to modulate cell-ECM interactions and is an important mediator of inflammation. In this study, we sought to investigate whether interactions established between galectin-3 and ECM glycoproteins are involved in monocyte migration, given that the mechanisms by which monocytes move across the endothelium and through the extravascular tissue are poorly understood. Using the in vitro transwell system, we demonstrated that monocyte migration was potentiated in the presence of galectin-3 plus laminin or fibronectin, but not vitronectin, and was dependent on the carbohydrate recognition domain of the lectin. Only galectin-3-fibronectin combinations potentiated the migration of monocyte-derived macrophages. In binding assays, galectin-3 did not bind to fibronectin, whereas both the full-length and the truncated forms of the lectin, which retains carbohydrate binding ability, were able to bind to laminin. Our results show that monocytes migrate through distinct mechanisms and selective interactions with the extracellular matrix driven by galectin-3. We suggest that the lectin may bridge monocytes to laminin and may also activate these cells, resulting in the positive regulation of other adhesion molecules and cell adhesion to fibronectin.

scholarly journals Clearance from plasma of lymph chylomicrons and chylomicron remnants labelled with 125I-tyramine-cellobiose

1992 ◽  
Vol 286 (3) ◽  
pp. 937-943 ◽  
Author(s):  
H L Ly ◽  
B C Mortimer ◽  
E Baker ◽  
T G Redgrave
Keyword(s):  
High Density Lipoprotein ◽  
Lipoprotein Lipase ◽  
Bovine Milk ◽  
Density Lipoprotein ◽  
High Density ◽  
Low Density ◽  
Apolipoprotein B48 ◽  
Chylomicron Remnants

The aims of the present study were to evaluate the metabolism of chylomicrons (CM) and of CM remnants after labelling with radioactive iodine and converting the iodinated CM into remnants in vitro. Lymph CM were radiolabelled with 125I or sham-labelled with 127I by either the ICl procedure or the tyramine-cellobiose (TC) procedure, then injected into rats. The clearance from plasma of the iodinated CM was compared with control non-iodinated lipid-labelled CM. After iodination with ICl, the plasma removal of endogenously labelled CM was significantly different from non-iodinated CM, with increased uptake of CM triacylglycerols by the liver. In contrast, the clearances from plasma and the uptake by organs of radiolabelled lipids of CM iodinated by the TC method (TC-CM) were similar to control CM. About 40% of the label from 125I-TC-CM was insoluble in 50% propan-2-ol, indicating association with CM apolipoprotein B48. Only about 8% of label was lipid soluble, mostly in phosphatidylethanolamine. Radioactivity from 125I-TC-CM injected intravenously in rats was cleared rapidly and by 30 min only 20% remained in plasma, whereas 48% was recovered in the liver. After fractionation of the plasma by density-gradient ultracentrifugation, most label remained associated with d (relative density) less than 1.006 lipoproteins. In intact rats label was also found associated with the low-density and high-density lipoprotein fractions of plasma. When the liver was excluded from circulation, the recovery of label in low-density- and high-density-lipoprotein fractions was greatly decreased. CM remnants were prepared in vivo by injecting 125I-TC-CM into functionally hepatectomized donors and compared with remnants prepared in vitro by incubation with purified bovine milk lipoprotein lipase. Although remnants prepared in vitro cleared from plasma slower than remnants prepared in vivo, the size, lipid composition and apolipoprotein profile on gradient PAGE of the remnants were similar. We conclude that labelling of CM by the TC method avoided the ‘artefactual’ changes in metabolism seen after labelling by the ICl procedure. CM remnants when prepared in vitro using lipoprotein lipase were found to be similar to those prepared in vivo after injection into functionally hepatectomized rats.

scholarly journals Association of the Endotoxin Antagonist E5564 with High-Density Lipoproteins In Vitro: Dependence on Low-Density and Triglyceride-Rich Lipoprotein Concentrations

2003 ◽  
Vol 47 (9) ◽  
pp. 2796-2803 ◽  
Author(s):  
Kishor M. Wasan ◽  
Olena Sivak ◽  
Richard A. Cote ◽  
Aaron I. MacInnes ◽  
Kathy D. Boulanger ◽  
...  
Keyword(s):  
Human Plasma ◽  
Human Subjects ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
High Density ◽  
High Density Lipoproteins ◽  
Low Density ◽  
Distribution Profile ◽  
Transfer Activity

ABSTRACT The objective of this study was to determine the distribution profile of the novel endotoxin antagonist E5564 in plasma obtained from fasted human subjects with various lipid concentrations. Radiolabeled E5564 at 1 μM was incubated in fasted plasma from seven human subjects with various total cholesterol (TC) and triglyceride (TG) concentrations for 0.5 to 6 h at 37°C. Following these incubations, plasma samples were separated into their lipoprotein and lipoprotein-deficient fractions by ultracentrifugation and were assayed for E5564 radioactivity. TC, TG, and protein concentrations in each fraction were determined by enzymatic assays. Lipoprotein surface charge within control and phosphatidylinositol-treated plasma and E5564’s influence on cholesteryl ester transfer protein (CETP) transfer activity were also determined. We observed that the majority of E5564 was recovered in the high-density lipoprotein (HDL) fraction. We further observed that incubation in plasma with increased levels of TG-rich lipoprotein (TRL) lipid (TC and TG) concentrations resulted in a significant increase in the percentage of E5564 recovered in the TRL fraction. In further experiments, E5564 was preincubated in human TRL. Then, these mixtures were incubated in hypolipidemic human plasma for 0.5 and 6 h at 37°C. Preincubation of E5564 in purified TRL prior to incubation in human plasma resulted in a significant decrease in the percentage of drug recovered in the HDL fraction and an increase in the percentage of drug recovered in the TRL and low-density lipoprotein fractions. These findings suggest that the majority of the drug binds to HDLs. Preincubation of E5564 in TRL prior to incubation in normolipidemic plasma significantly decreased the percentage of drug recovered in the HDL fraction. Modifications to the lipoprotein negative charge did not alter the E5564 concentration in the HDL fraction. In addition, E5564 does not influence CETP-mediated transfer activity. Information from these studies could be used to help identify the possible components of lipoproteins which influence the interaction of E5564 with specific lipoprotein particles.

scholarly journals High-Density Lipoproteins Limit Neutrophil-Induced Damage to the Blood–Brain Barrier in Vitro

2013 ◽  
Vol 33 (4) ◽  
pp. 575-582 ◽  
Author(s):  
Quoc Bao Dang ◽  
Bertrand Lapergue ◽  
Alexy Tran-Dinh ◽  
Devy Diallo ◽  
Juan-Antonio Moreno ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Blood Brain Barrier ◽  
Extracellular Matrix Proteins ◽  
High Density ◽  
Matrix Proteins ◽  
Brain Barrier ◽  
High Density Lipoproteins ◽  
Blood Brain

Breakdown of the blood–brain barrier (BBB) is a key step associated with ischemic stroke and its increased permeability causes extravasation of plasma proteins and circulating leukocytes. Polymorphonuclear neutrophil (PMN) proteases may participate in BBB breakdown. We investigated the role of PMNs in ischemic conditions by testing their effects on a model of BBB in vitro, under oxygen-glucose deprivation (OGD) to mimic ischemia, supplemented or not with high-density lipoproteins (HDLs) to assess their potential protective effects. Human cerebral endothelial cells cultured on transwells were incubated for 4 hours under OGD conditions with or without PMNs and supplemented or not with HDLs or alpha-1 antitrypsin (AAT, an elastase inhibitor). The integrity of the BBB was then assessed and the effect of HDLs on PMN-induced proteolysis of extracellular matrix proteins was evaluated. The release of myeloperoxidase and matrix metalloproteinase 9 (MMP-9) by PMNs was quantified. Polymorphonuclear neutrophils significantly increased BBB permeability under OGD conditions via proteolysis of extracellular matrix proteins. This was associated with PMN degranulation. Addition of HDLs or AAT limited the proteolysis and associated increased permeability by inhibiting PMN activation. Our results suggest a deleterious, elastase-mediated role of activated PMNs under OGD conditions leading to BBB disruption that could be inhibited by HDLs.

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