scholarly journals The alpha 1/beta 1 and alpha 6/beta 1 integrin heterodimers mediate cell attachment to distinct sites on laminin.

1990 ◽  
Vol 110 (6) ◽  
pp. 2175-2184 ◽  
Author(s):  
D E Hall ◽  
L F Reichardt ◽  
E Crowley ◽  
B Holley ◽  
H Moezzi ◽  
...  
Keyword(s):  
Cell Attachment ◽  
Collagen Iv ◽  
Cellular Interactions ◽  
Beta 1 Integrin ◽  
Alpha Beta ◽  
Choriocarcinoma Cells ◽  
Mediate Cell ◽  
The Individual ◽  
A Site ◽  
Jar Cells

This study was undertaken to determine the roles of individual alpha/beta 1 integrin heterodimers in promoting cellular interactions with the different attachment-promoting domains of laminin (LN). To do this, antibodies to the integrin beta 1 subunit or to specific integrin alpha subunits were tested for effects on cell attachment to LN, to elastase fragments E1-4 and E1, derived from the short arms and core of LN's cruciform structure, and to fragment E8 derived from the long arm of this structure. The human JAR choriocarcinoma cells used in this study attached to LN and to fragments E1 and E8. Attachment to E1-4 required a much higher substrate coating concentration, suggesting that it is a poor substrate for JAR cell attachment. The ability of cells to attach to different LN domains suggested the presence of more than one LN receptor. These multiple LN receptors were shown to be beta 1 integrin heterodimers because antibodies to the integrin beta 1 subunit inhibited attachment of JAR cells to LN and its three fragments. To identify the individual integrin alpha/beta 1 heterodimers that mediate interactions with these LN domains, mAbs specific for individual beta 1 heterodimers in human cells were used to study JAR cell interactions with LN and its fragments. An anti-alpha 6/beta 1-specific mAb, GoH3, virtually eliminated cell attachment to E8 and partially inhibited attachment to E1 and intact LN. Thus the major alpha 6/beta 1 attachment domain is present in fragment E8. An alpha 1/beta 1-specific mAb (S2G3) strongly inhibited cell attachment to collagen IV and partially inhibited JAR attachment to LN fragment E1. Thus, the alpha 1/beta 1 heterodimer is a dual receptor for collagen IV and LN, interacting with LN at a site in fragment E1. In combination, the anti-alpha 1- and anti-alpha 6-specific antibodies completely inhibited JAR cell attachment to LN and fragment E1. Thus, the alpha 1/beta 1 and alpha 6/beta 1 integrin heterodimers each function as LN receptors and act together to mediate the interactions of human JAR choriocarcinoma cells with LN.

scholarly journals Expression and presence of osteopontin and integrins in the bovine oviduct during the oestrous cycle

Reproduction ◽  
2003 ◽  
pp. 721-729 ◽  
Author(s):  
C Gabler ◽  
DA Chapman ◽  
GJ Killian
Keyword(s):  
Luteal Phase ◽  
Cell Attachment ◽  
Oestrous Cycle ◽  
Functional Roles ◽  
Late Luteal Phase ◽  
Mrna Content ◽  
Mediate Cell ◽  
Alpha V Beta 3 ◽  
A Site ◽  
Oviductal Fluid

Osteopontin and integrin alpha(v)beta(3) are known to mediate cell-cell attachment and cell migration. Western blot analysis was used to demonstrate the presence of osteopontin in oviductal fluid collected from ampullar and isthmic regions. Three different osteopontin isoforms of 55 kDa, 48 kDa and 25 kDa were detected in the oviductal fluid. Each isoform was observed during the luteal and non-luteal phases and in both ampullar and isthmic fluids. The 25 kDa osteopontin was the most prevalent isoform in oviductal fluid except in isthmic fluid during the non-luteal phase of the oestrous cycle. RT-PCR was performed with RNA from oviductal cells collected from cows in the post-ovulatory, early to mid-luteal, late luteal or pre-ovulatory stages of the oestrous cycle to reveal the oviduct as a site of osteopontin and integrin synthesis. Only one osteopontin mRNA transcript was detected, and amounts did not vary throughout the oestrous cycle. In contrast, the relative expression of the integrin subtypes alpha(v) and beta(1) during the late luteal phase was lower compared with the other oestrous cycle phases. Integrin beta(3) mRNA content increased significantly from the lowest level during the late luteal phase to the highest level before ovulation. In conclusion, differential presence of osteopontin isoforms and integrins in the bovine oviduct throughout the oestrous cycle indicate that osteopontin-integrin interactions have functional roles in normal oviduct physiology which may potentially influence interactions between the gametes, the embryo, and the epithelium.

scholarly journals Multiple cell surface receptors for the short arms of laminin: alpha 1 beta 1 integrin and RGD-dependent proteins mediate cell attachment only to domains III in murine tumor laminin.

1991 ◽  
Vol 113 (4) ◽  
pp. 931-941 ◽  
Author(s):  
S L Goodman ◽  
M Aumailley ◽  
H von der Mark
Keyword(s):  
Cell Surface ◽  
Cell Attachment ◽  
Heat Denaturation ◽  
Surface Receptors ◽  
Murine Tumor ◽  
Heat Stable ◽  
Multiple Cell ◽  
Beta 1 Integrin ◽  
Mediate Cell ◽  
Alpha V Beta 3

Cell surface molecules that interact with the cross formed by the three short arms of murine tumor laminin were studied using thermal perturbation, antibody and peptide blocking, and affinity chromatography. Several potential receptors for the laminin short arms were revealed that differed from those mediating cell attachment to the E8 (long arm) fragment. Two cell lines, Rugli and L8 attached well to E1-X (short arm) fragments of laminin. This attachment was blocked by antibodies against alpha 1 integrin chains. Other cells were unable to attach strongly to E1-X, but attached to P1. This attachment was unaffected by anti-beta 1 integrin antibodies, but specifically blocked by the peptide GRGDS. By contrast, binding of Rugli cells was RGD independent and blocked by anti-beta 1 integrin antibodies. G7 and C2C12 myoblasts were very sensitive to GRGDS (ID50 approximately 2 micrograms.ml-1) for attachment to P1 which implied that a non-beta 1 series integrin, possibly alpha v beta 3, was involved. On heat denaturation of P1(3) attachment remained sensitive to RGDS and ID50 was unchanged. On heat denaturation of E1-X, attachment remained sensitive to RGDS but the ID50 increased to approximately 200 micrograms.ml-1. Cellular beta 1 integrins were retained on laminin affinity columns. A beta 1 integrin with an approximately 190 kD alpha-chain could be isolated from Rugli cells whose attachment could be blocked by anti-alpha 1 antibodies and not from cells blocked by RGDS peptides. Anti-alpha 1 antibodies blocked Rugli attachment to native laminin, but only when the E8 cell binding sites on laminin were also blocked. Thus, a receptor related to alpha 1 beta 1 integrin can function simultaneously with a receptor for E8. Anti-alpha 1 also blocked attachment to heated laminin, suggesting that the heat-stable attachment activity in laminin involved the E1-X binding site. Thus, at least two putative receptors mediate attachment to the short arms of laminin. One, related to alpha 1 beta 1 integrin, recognizes RGDS-independent sites in E1-X defined by P1 (within domains III, IIIa, IIIb), and one is an RGD-dependent molecule recognizing sites in P1, and is not a beta 1 integrin.

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

1994 ◽  
Vol 124 (3) ◽  
pp. 373-380 ◽  
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.

scholarly journals Silencing of the Gene for the α-Subunit of Human Chorionic Gonadotropin by the Embryonic Transcription Factor Oct-3/4

1997 ◽  
Vol 11 (11) ◽  
pp. 1651-1658 ◽  
Author(s):  
Limin Liu ◽  
Douglas Leaman ◽  
Michel Villalta ◽  
R. Michael Roberts
Keyword(s):  
Transcription Factor ◽  
Binding Site ◽  
Gene Promoter ◽  
Site Directed Mutagenesis ◽  
Mobility Shift ◽  
Α Subunit ◽  
Choriocarcinoma Cells ◽  
Human Choriocarcinoma Cells ◽  
Electrophoretic Mobility Shift Assays ◽  
Jar Cells

Abstract CG is required for maintenance of the corpus luteum during pregnancy in higher primates. As CG is a heterodimeric molecule, some form of coordinated control must be maintained over the transcription of its two subunit genes. We recently found that expression of human CG β-subunit (hCGβ) in JAr human choriocarcinoma cells was almost completely silenced by the embryonic transcription factor Oct-3/4, which bound to a unique ACAATAATCA octameric sequence in the hCGβ gene promoter. Here we report that Oct-3/4 is also a potent inhibitor of hCG α-subunit (hCGα) expression in JAr cells. Oct-3/4 reduced human GH reporter expression from the −170 hCGα promoter in either the presence or absence of cAMP by about 70% in transient cotransfection assays, but had no effect on expression from either the −148 hCGα or the −99 hCGα promoter. Unexpectedly, no Oct-3/4-binding site was identified within the −170 to −148 region of the hCGα promoter, although one was found around position −115 by both methylation interference footprinting and electrophoretic mobility shift assays. Site-directed mutagenesis of this binding site destroyed the affinity of the promoter for Oct-3/4, but did not affect repression of the promoter. Therefore, inhibition of hCGα gene transcription by Oct-3/4 appears not to involve direct binding of this factor to the site responsible for silencing. When stably transfected into JAr cells, Oct-3/4 reduced the amounts of both endogenous hCGα mRNA and protein by 70–80%. Oct-3/4 is therefore capable of silencing both hCGα and hCGβ gene expression. We suggest that as the trophoblast begins to form, reduction of Oct-3/4 expression permits the coordinated onset of transcription from the hCGα and hCGβ genes.

scholarly journals Specific Binding of Rubidium in Chlorella

1962 ◽  
Vol 45 (5) ◽  
pp. 959-977 ◽  
Author(s):  
Dan Cohen
Keyword(s):  
Active Transport ◽  
Binding Sites ◽  
Specific Binding ◽  
High Concentration ◽  
External Concentration ◽  
Specific Binding Sites ◽  
Dense Suspension ◽  
Concentration Of Ions ◽  
The Individual ◽  
A Site

Specific binding sites for potassium, which may be components of the carriers for active transport for K in Chlorella, were characterized by their capacity to bind rubidium. A dense suspension was allowed to take up Rb86 from a low concentration of Rb86 and a high concentration of ions which saturate non-specific sites. The amount bound was derived from the increase in the external concentration of Rb86 following addition of excess potassium. The sites were heterogeneous. The average affinity of Rb and various other ions for the sites was determined by plotting the degree of displacement of Rb86 against log molar concentration of the individual ions. Interpolation gave the concentration for 50 per cent displacement of Rb, which is inversely related to affinity. The order of affinity was not changed when the cells were frozen, or boiled either in water or in 70 per cent ethanol. The affinity is maximal for ions with a crystalline radius of 1.3 to 1.5 A and a high polarizability, and is not related to the hydrated radius or valency. It is suggested that binding groups in a site are rigidly arranged, the irregular space between them being 2.6 to 3.0 A across, so that affinity is high for ions of this diameter and high polarizability.

RevisitingCriticalLegal Pluralism: Normative Contestations in the Afghan Courtroom

2017 ◽  
Vol 4 (1) ◽  
pp. 229-255 ◽  
Author(s):  
Nafay CHOUDHURY
Keyword(s):  
Methodological Approach ◽  
Legal Pluralism ◽  
Legal Order ◽  
Fully Discrete ◽  
Active Defence ◽  
Defence Lawyer ◽  
The Individual ◽  
A Site ◽  
Individual Choices ◽  
Shed Light

AbstractThis paper revisits the concept ofcriticallegal pluralism, which treats the individual as a site of normativity with the capacity to create legal knowledge. To help operationalize the usage of critical legal pluralism, I propose a methodological approach that places the individual’s ability to makes choices along a continuum. On one side of continuum, legal pluralism can be viewed as facilitating fully discrete choices that ascribe to one legal order or another. On the other side, the ability to make individual choices is curtailed because of the presence of a hegemonic legal order. This simple continuum helps to shed light on the complex considerations that affect individual choices, which in turn affect how various legal orders are legitimated. The paper then considers how critical legal pluralism can enrich the discussion on the legal system of Afghanistan, focusing on interviews with two Afghan justice actors: a former judge and an active defence lawyer.

scholarly journals Differences in acid phosphomonoesterase activity in forest soils of the Smrk Massive in the Moravskoslezské Beskydy Mts. (Czech Republic)

Beskydy ◽  
2012 ◽  
Vol 5 (2) ◽  
pp. 135-152
Author(s):  
A. Bajer ◽  
P. Samec ◽  
M. Žárník
Keyword(s):  
Relative Size ◽  
Chemical Properties ◽  
Principal Component ◽  
European Beech ◽  
Soil Characteristics ◽  
Strong Correlations ◽  
Spruce Stands ◽  
The Individual ◽  
A Site

The purpose of this paper is to determine the individual relations between APEA and specific soils and environmental factors. To disclose these relations, analysis of component vectors and principal component analysis (PCA) were performed. Vectors of soil characteristics with participation of APEA (aAKFE) and vectors of pedochemical variables (aCHEM) were also calculated. Their ratio (ia) indicated the relative size of the APEA impact on the relations between pedochemical characteristics. Based on the statistical analyses, different role of APEA in Norway spruce and in European beech stands was detected. While APEA in spruce stands did not show significant correlations with the other examined soil chemical properties, soils under beech stands displayed strong correlations with some of the pedochemical variables. The idea of this research is to find out whether APEA could be used as an indicator of forest vegetation status and of the anthropogenic load on a site.

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

Development ◽  
1991 ◽  
Vol 113 (4) ◽  
pp. 1069-1084 ◽  
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.

Stimulation of tyrosine phosphorylation of distinct proteins in response to antibody-mediated ligation and clustering of alpha 3 and alpha 6 integrins

1995 ◽  
Vol 108 (3) ◽  
pp. 1165-1174
Author(s):  
K. Jewell ◽  
C. Kapron-Bras ◽  
P. Jeevaratnam ◽  
S. Dedhar
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Kinase Inhibitor ◽  
Cell Attachment ◽  
Umbilical Vein ◽  
Integrin Receptors ◽  
Human Prostate Carcinoma ◽  
Beta 1 Integrin ◽  
Umbilical Vein Endothelial Cells ◽  
Stimulation Of

The interaction of cells with components of the extracellular matrix through their integrin receptors results in the stimulation of tyrosine phosphorylation of several proteins, suggesting that these receptors play a key role in signal transduction. Here we report that antibody-mediated ligation and clustering of alpha 3 beta 1 and alpha 6 beta 1/alpha 6 beta 4 integrins resulted in the stimulation of tyrosine phosphorylation of proteins that are specific for each heterodimer. Thus, ligation and clustering of the alpha 3 beta 1 integrin on human prostate carcinoma cells (PC-3) and human umbilical vein endothelial cells (HUVEC) with anti-alpha 3 antibodies resulted in the stimulation of tyrosine phosphorylation of a 55 kDa protein. In contrast, ligation and clustering of the alpha 6 beta 1 integrin on these cells with anti-alpha 6 antibody resulted in the dramatic stimulation of tyrosine phosphorylation of a 90 kDa protein in addition to a 52 kDa protein, and ligation and clustering of alpha 5 beta 1 on HUVEC did not result in the apparent stimulation of tyrosine phosphorylation of any proteins. Clustering with anti-beta 1 antibodies triggered the tyrosine phosphorylation of all of these proteins, whereas ligation and clustering of PC-3 cells with an anti-beta 4 antibody resulted in the tyrosine phosphorylation of a distinct 62 kDa protein. Since the PC-3 cells express both alpha 6 beta 1 and alpha 6 beta 4, these data suggest that these two receptors can transduce distinct signals. All of the phosphorylations could be inhibited by treating the cells with Genistein, a tyrosine kinase inhibitor. Antibody-mediated ligation and clustering of integrins on the two types of cells did not result in the stimulation of tyrosine phosphorylation of pp125 focal adhesion kinase, although this was observed upon cell attachment and spreading on fibronectin, laminin and anti-alpha 3 monoclonal antibody. Collectively, these data demonstrate that cross-linking of different integrin heterodimers can stimulate tyrosine kinase activities, leading to the phosphorylation of distinct proteins, which are also different from those observed when cells are allowed to spread on a matrix.

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