Substrate adhesion of rat hepatocytes: on the mechanism of attachment to fibronectin.

We examined the mechanisms of cell attachment to fibronectin-coated substrates. Inhibition of cell attachment was obtained by species-specific antifibronectin antibodies, which presumably recognize a distinct antigenic structure in the protein located at, or in the immediate vicinity of, the cell-binding site. The inhibiting antibodies could be adsorbed on a column of Sepharose substituted with plasma fibronectin. The initial phase of cell attachment was also inhibited by addition of soluble fibronectin to the incubation medium in a reaction that exhibited specificity and concentration dependence. These data suggest that cell-binding sites are available in an active form on the surface of soluble fibronectin. However, the inhibitory effect of fibronectin was greatly enhanced by adding the protein together with heparin, heparan sulfate, collagen, or a fibronectin-binding collagen peptide (CB-7), which is consistent with an "activation" of fibronectin on binding to these matrix components. A similar activation of fibronectin was obtained by cleaving the protein with trypsin. We discuss these findings in relation to conformational rearrangements in the fibronectin molecule. Data is presented supporting a mechanism of cell attachment to fibronectin involving multiple weak interactions between cellular receptors and substrate molecules, although some steps in the attachment process appear to disobey the requirements for such a mechanism.

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Substrate adhesion of rat hepatocytes: a comparison of laminin and fibronectin as attachment proteins.

The Journal of Cell Biology ◽

10.1083/jcb.90.1.260 ◽

1981 ◽

Vol 90 (1) ◽

pp. 260-264 ◽

Cited By ~ 108

Author(s):

S Johansson ◽

L Kjellén ◽

M Höök ◽

R Timpl

Keyword(s):

Cell Attachment ◽

Periodate Oxidation ◽

Rat Hepatocytes ◽

The Other ◽

Present Communication ◽

Cellular Receptors ◽

Initial Cell ◽

Substrate Adhesion ◽

Basement Membrane Protein ◽

Attachment Proteins

In previous studies rat hepatocytes have been shown to adhere to substrates composed of collagen or fibronectin. In the present communication, the basement membrane protein laminin is reported to mediated the attachment and spreading of hepatocytes. The cell attachment-mediating activity of laminin was compared with that of fibronectin. The activity of fibronectin was heat sensitive, whereas laminin retained its activity after boiling. On the other hand, reduction and alkylation or periodate oxidation of the proteins affected only the cell attachment activity of laminin. Preincubation of cells with soluble fibronectin inhibited initial cell attachment to fibronectin but not to laminin substrates, and, reversely, soluble laminin selectively inhibited cell attachment to laminin. These results suggest that attachment of cells to substrates of the two proteins involves different cellular receptors recognizing distinct and nonidentical structures in the proteins.

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Inhibitory effect of Tumor Necrosis Factor α, Interleukin 2, and Interferon γ on CTGF expression in cultured rat hepatocytes

Zeitschrift für Gastroenterologie ◽

10.1055/s-0029-1191794 ◽

2009 ◽

Vol 47 (01) ◽

Author(s):

I Peredniene ◽

OA Gressner ◽

B Lahme ◽

K Rehbein ◽

AM Gressner

Keyword(s):

Tumor Necrosis Factor ◽

Tumor Necrosis ◽

Tumor Necrosis Factor Α ◽

Interleukin 2 ◽

Rat Hepatocytes ◽

Inhibitory Effect ◽

Interferon Γ ◽

Cultured Rat Hepatocytes ◽

Factor Α ◽

Necrosis Factor

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A rapid, parasite-dependent cellular response to Dirofilaria immitis in the Mongolian jird (Meriones unguiculatus)

Parasites & Vectors ◽

10.1186/s13071-020-04455-x ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Christopher C. Evans ◽

Katherine M. Day ◽

Yi Chu ◽

Bridget Garner ◽

Kaori Sakamoto ◽

...

Keyword(s):

Cellular Response ◽

Dirofilaria Immitis ◽

Cell Attachment ◽

Early Response ◽

Meriones Unguiculatus ◽

Filarial Parasite ◽

Immune Mediated ◽

Secretory Products ◽

Species Specific

Abstract Background The Mongolian jird (Meriones unguiculatus) has long been recognized as a permissive host for the filarial parasite Brugia malayi; however, it is nonpermissive to another filarial parasite, canine heartworm (Dirofilaria immitis). By elucidating differences in the early response to infection, we sought to identify mechanisms involved in the species-specific clearance of these parasites. We hypothesized that the early clearance of D. immitis in intraperitoneal infection of the jird is immune mediated and parasite species dependent. Methods Jird peritoneal exudate cells (PECs) were isolated and their attachment to parasite larvae assessed in vitro under various conditions: D. immitis and B. malayi cultured separately, co-culture of both parasites, incubation before addition of cells, culture of heat-killed parasites, and culture with PECs isolated from jirds with mature B. malayi infection. The cells attaching to larvae were identified by immunohistochemistry. Results In vitro cell attachment to live D. immitis was high (mean = 99.6%) while much lower for B. malayi (mean = 5.56%). This species-specific attachment was also observed when both filarial species were co-cultured, with no significant change from controls (U(9, 14) = 58.5, p = 0.999). When we replicated these experiments with PECs derived from jirds subcutaneously infected with B. malayi, the results were similar (99.4% and 4.72% of D. immitis and B. malayi, respectively, exhibited cell attachment). Heat-killing the parasites significantly reduced cell attachment to D. immitis (mean = 71.9%; U(11, 14) = 7.5, p < 0.001) while increasing attachment to B. malayi (mean = 16.7%; U(9, 15) = 20, p = 0.002). Cell attachment to both species was reduced when larvae were allowed a 24-h pre-incubation period prior to the addition of cells. The attaching cells were identified as macrophages by immunohistochemistry. Conclusions These results suggest a strongly species-dependent response from which B. malayi could not confer protection by proxy in co-culture. The changes in cell attachment following heat-killing and pre-incubation suggest a role for excretory/secretory products in host immune evasion and/or antigenicity. The nature of this attachment is the subject of ongoing study and may provide insight into filarial host specificity.

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Effects of extracellular ATP on hepatic fatty acid metabolism

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1996.270.4.g701 ◽

1996 ◽

Vol 270 (4) ◽

pp. G701-G707 ◽

Cited By ~ 1

Author(s):

M. Guzman ◽

G. Velasco ◽

J. Castro

Keyword(s):

Fatty Acid ◽

De Novo ◽

Specific Inhibitor ◽

Rat Hepatocytes ◽

Inhibitory Effect ◽

Extracellular Atp ◽

Acid Oxidation ◽

A 23187 ◽

Malonyl Coa ◽

Cpt I

Incubation of rat hepatocytes with extracellular ATP inhibited acetyl-CoA carboxylase (ACC) activity and fatty acid synthesis de novo, with a concomitant decrease of intracellular malonyl-CoA concentration. However, both carnitine O-palmitoyltransferase I (CPT-I) activity and ketogenesis from palmitate were inhibited in parallel by extracellular ATP. The inhibitory effect of extracellular ATP on ACC and CPT-I activities was not evident in Ca2+ -depleted hepatocytes. Incubation of hepatocytes with thapsigargin, 2,5-di-(t-butyl)-1,4-benzohydroquinone (BHQ), or A-23187, compounds that increase cytosolic free Ca2+ concentration ([Ca2+]i), depressed ACC activity, whereas CPT-I activity was unaffected. The phorbol ester 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) increased ACC activity, whereas it decreased CPT-I activity in a nonaddictive manner with respect to extracellular ATP. The inhibitory effect of extracellular ATP on ACC activity was also evident in the presence of bisindolyl-maleimide, a specific inhibitor of protein kinase C (PKC), whereas this compound abolished the extracellular ATP-mediated inhibition of CPT-I. In addition, the PMA-induced inhibition of CPT-I was not potentiated by thapsigargin, BHQ, or A-23187. Results thus show 1) that the intracellular concentration of malonyl-CoA is not the factor responsible for the inhibition of hepatic long-chain fatty acid oxidation by extracellular ATP, and 2) that the inhibition of ACC by extracellular ATP may be mediated by an elevation of [Ca2+]i, whereas CPT-I may be inhibited by extracellular ATP through a PKC-dependent mechanism.

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Isolation of a highly specific ligand for the alpha 5 beta 1 integrin from a phage display library

The Journal of Cell Biology ◽

10.1083/jcb.124.3.373 ◽

1994 ◽

Vol 124 (3) ◽

pp. 373-380 ◽

Cited By ~ 225

Author(s):

E Koivunen ◽

B Wang ◽

E Ruoslahti

Keyword(s):

Phage Display ◽

Cyclic Peptide ◽

Cell Attachment ◽

Phage Display Library ◽

Cell Binding ◽

Rgd Peptides ◽

Beta 1 Integrin ◽

Alpha V Beta 3 ◽

Integrin Ligand ◽

Specific Ligand

Our previous studies showed that the alpha 5 beta 1 integrin selects cysteine pair-containing RGD peptides from a phage display library based on a random hexapeptide. We have therefore searched for more selective peptides for this integrin using a larger phage display library, where heptapeptides are flanked by cysteine residues, thus making the inserts potentially cyclic. Most of the phage sequences that bound to alpha 5 beta 1 (69 of 125) contained the RGD motif. Some of the heptapeptides contained an NGR motif. As the NGR sequence occurs in the cell-binding region of the fibronectin molecule, this sequence could contribute to the specific recognition of fibronectin by alpha 5 beta 1. Selection for high affinity peptides for alpha 5 beta 1 surprisingly yielded a sequence RRETAWA that does not bear obvious resemblance to known integrin ligand sequences. The synthetic cyclic peptide GACRRETAWACGA (*CRRETAWAC*) was a potent inhibitor of alpha 5 beta 1-mediated cell attachment to fibronectin. This peptide is nearly specific for the alpha 5 beta 1 integrin, because much higher concentrations were needed to inhibit the alpha v beta 1 integrin, and there was no effect on alpha v beta 3- and alpha v beta 5-mediated cell attachment to vitronectin. The peptide also did not bind to the alpha IIb beta 3 integrin. *CRRETAWAC* appears to interact with the same or an overlapping binding site in alpha 5 beta 1 as RGD, because cell attachment to *CRRETAWAC* coated on plastic was divalent cation dependent and could be blocked by an RGD-containing peptide. These results reveal a novel binding specificity in the alpha 5 beta 1 integrin.

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Effects of Carrier Material and Design on Microalgae Attachment for Biofuel Manufacturing: A Literature Review

ASME 2010 International Manufacturing Science and Engineering Conference, Volume 1 ◽

10.1115/msec2010-34150 ◽

2010 ◽

Cited By ~ 2

Author(s):

Yan Cui ◽

Wenqiao Wayne Yuan ◽

Zhijian Pei

Keyword(s):

Free Energy ◽

Large Scale ◽

Cell Attachment ◽

Cost Effective ◽

Surface Wettability ◽

Biofuel Production ◽

Algae Biofuels ◽

Attachment Strength ◽

Species Specific ◽

Continuous Use

Continuous use of petroleum derived fuels is widely recognized as unsustainable due to depleting supplies and the accumulation of greenhouse gases in the environment. Renewable, carbon neutral transport fuels are needed for environmental and economic sustainabilities. Algae have been demonstrated to be one of the most promising sources for biofuel production. However, large-scale algae production and harvesting for energy manufacturing are too costly using existing methods. The approach of growing algae on solid carriers is innovative and can potentially lead to cost-effective manufacturing of algae biofuels. As cells approach to the solid surface, many factors come in to influence microbial attachment such as the surface wettability, free energy, polarity, roughness and topography. Surface wettability plays an important role in the initial cell attachment. For further contact, surface free energy and polarity are more directly related to cell-substratum attachment strength. Surface roughness and texture are species-specific parameters and have been applied widely in attachment studies.

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Lipoprotein-associated phospholipase A2 (Lp-PLA2) as a therapeutic target to prevent retinal vasopermeability during diabetes

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1514213113 ◽

2016 ◽

Vol 113 (26) ◽

pp. 7213-7218 ◽

Cited By ~ 30

Author(s):

Paul Canning ◽

Bridget-Ann Kenny ◽

Vivien Prise ◽

Josephine Glenn ◽

Mosharraf H. Sarker ◽

...

Keyword(s):

Therapeutic Target ◽

Vascular Function ◽

Specific Inhibitor ◽

Inhibitory Effect ◽

Diabetic Rats ◽

Brown Norway ◽

Vegf Receptor ◽

Blood Retinal Barrier ◽

Species Specific ◽

Brb Breakdown

Lipoprotein-associated phospholipase A2 (Lp-PLA2) hydrolyses oxidized low-density lipoproteins into proinflammatory products, which can have detrimental effects on vascular function. As a specific inhibitor of Lp-PLA2, darapladib has been shown to be protective against atherogenesis and vascular leakage in diabetic and hypercholesterolemic animal models. This study has investigated whether Lp-PLA2 and its major enzymatic product, lysophosphatidylcholine (LPC), are involved in blood–retinal barrier (BRB) damage during diabetic retinopathy. We assessed BRB protection in diabetic rats through use of species-specific analogs of darapladib. Systemic Lp-PLA2 inhibition using SB-435495 at 10 mg/kg (i.p.) effectively suppressed BRB breakdown in streptozotocin-diabetic Brown Norway rats. This inhibitory effect was comparable to intravitreal VEGF neutralization, and the protection against BRB dysfunction was additive when both targets were inhibited simultaneously. Mechanistic studies in primary brain and retinal microvascular endothelial cells, as well as occluded rat pial microvessels, showed that luminal but not abluminal LPC potently induced permeability, and that this required signaling by the VEGF receptor 2 (VEGFR2). Taken together, this study demonstrates that Lp-PLA2 inhibition can effectively prevent diabetes-mediated BRB dysfunction and that LPC impacts on the retinal vascular endothelium to induce vasopermeability via VEGFR2. Thus, Lp-PLA2 may be a useful therapeutic target for patients with diabetic macular edema (DME), perhaps in combination with currently administered anti-VEGF agents.

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Avian neural crest cell attachment to laminin: involvement of divalent cation dependent and independent integrins

Development ◽

10.1242/dev.113.4.1069 ◽

1991 ◽

Vol 113 (4) ◽

pp. 1069-1084 ◽

Cited By ~ 2

Author(s):

T. Lallier ◽

M. Bronner-Fraser

Keyword(s):

Neural Crest ◽

Cell Attachment ◽

Divalent Cations ◽

Neural Crest Cell ◽

Neural Crest Cells ◽

Cell Interaction ◽

Cell Binding ◽

Cell Adherence ◽

Beta 1 Integrin ◽

Crest Cell

The mechanisms of neural crest cell interaction with laminin were explored using a quantitative cell attachment assay. With increasing substratum concentrations, an increasing percentage of neural crest cells adhere to laminin. Cell adhesion at all substratum concentrations was inhibited by the CSAT antibody, which recognizes the chick beta 1 subunit of integrin, suggesting that beta 1-integrins mediate neural crest cell interactions with laminin. The HNK-1 antibody, which recognizes a carbohydrate epitope, inhibited neural crest cell attachment to laminin at low coating concentrations (greater than 1 microgram ml-1; Low-LM), but not at high coating concentration of laminin (10 micrograms ml-1; High-LM). Attachment to Low-LM occurred in the absence of divalent cations, whereas attachment to High-LM required greater than 0.1 mM Ca2+ or Mn2+. Neural crest cell adherence to the E8 fragment of laminin, derived from its long arm, was similar to that on intact laminin at high and low coating concentrations, suggesting that this fragment contains the neural crest cell binding site(s). The HNK-1 antibody recognizes a protein of 165,000 Mr which is also found in immunoprecipitates using antibodies against the beta 1 subunit of integrin and is likely to be an integrin alpha subunit or an integrin-associated protein. Our results suggest that the HNK-1 epitope on neural crest cells is present on or associated with a novel or differentially glycosylated form of beta 1-integrin, which recognizes laminin in the apparent absence of divalent cations. We conclude that neural crest cells have at least two functionally independent means of attachment to laminin which are revealed at different substratum concentrations and/or conformations of laminin.

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Characterization of a type IV collagen major cell binding site with affinity to the alpha 1 beta 1 and the alpha 2 beta 1 integrins.

The Journal of Cell Biology ◽

10.1083/jcb.113.6.1475 ◽

1991 ◽

Vol 113 (6) ◽

pp. 1475-1483 ◽

Cited By ~ 157

Author(s):

P Vandenberg ◽

A Kern ◽

A Ries ◽

L Luckenbill-Edds ◽

K Mann ◽

...

Keyword(s):

Binding Site ◽

Type Iv Collagen ◽

Cell Attachment ◽

Cell Surface Receptor ◽

Helical Conformation ◽

Amino Acid Residues ◽

Cell Binding ◽

Type Iv ◽

Depth Study ◽

Surface Receptor

The aim of this investigation was to identify the domains of type IV collagen participating in cell binding and the cell surface receptor involved. A major cell binding site was found in the trimeric cyanogen bromide-derived fragment CB3, located 100 nm away from the NH2 terminus of the molecule, in which the triple-helical conformation is stabilized by interchain disulfide bridges. Cell attachment assays with type IV collagen and CB3 revealed comparable cell binding activities. Antibodies against CB3 inhibited attachment on fragment CB3 completely and on type IV collagen to 80%. The ability to bind cells was strictly conformation dependent. Four trypsin derived fragments of CB3 allowed a closer investigation of the binding site. The smallest, fully active triple-helical fragment was (150)3-amino acid residues long. It contained segments of 27 and 37 residues, respectively, at the NH2 and COOH terminus, which proved to be essential for cell binding. By affinity chromatography on Sepharose-immobilized CB3, two receptor molecules of the integrin family, alpha 1 beta 1 and alpha 2 beta 1, were isolated. Their subunits were identified by sequencing the NH2 termini or by immunoblotting. The availability of fragment CB3 will allow for a more in-depth study of the molecular interaction of a short, well defined triple-helical ligand with collagen receptors alpha 1 beta 1 and alpha 2 beta 1.

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