Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 1408384

[Fibronectins].

C Stamm·Y Sarret·D Schmitt·J Thivolet
View original source ↗Export metadata ↓

Abstract

Fibronectins are complex glycoprotein macromolecules whose molecular weight is 440 kilodaltons. These proteins, found throughout the body, are soluble in biological fluids and insoluble in connective tissue. They contribute to tissue morphogenesis through multiple interactions with cells and extracellular matrix components. Fibronectins play a key role in cell attachment and remodeling during embryonic development, in cell migration and anchorage during wound healing, and in immune responses. This review discusses the structure of fibronectins, their integrin cell receptors, their biologic properties and their implications for diseases.

Explore related subjects

Cell AdhesionCell MovementFibronectinsHumansIntegrinsKeratinocytesWound HealingEnglish AbstractJournal ArticleReview

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

C Stamm, Y Sarret, D Schmitt, J Thivolet. 1992. [Fibronectins].. https://pubmed.ncbi.nlm.nih.gov/1408384/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1996

Potential role of membrane internalization and vesicle fusion in adhesion of neutrophils in response to lipopolysaccharide and TNF.

Human polymorphonuclear leukocytes (PMN) respond to LPS with strongly increased integrin-mediated adhesion. While the first step of this process has been identified as the interaction of LPS with CD14 on the cell surface, subsequent steps remain to be elucidated. The experiments presented here suggest that monomeric LPS is internalized in vesicles, and uptake may be required for signaling. Fluorescently labeled LPS presented as monomeric complexes with soluble CD14 appeared in the plasma membrane of PMN by 5 min and was concentrated in cytoplasmic vesicles by 20 min. Adhesion in response to LPS/soluble CD14 occurred only after a 15- to 20-min lag period, consistent with endocytosis occurring before signal generation. In contrast, there was no time lag for adhesion in response to the formyl peptide formyl-norleucyl-leucyl-phenylalanine (fNLLP). Adhesion in response to LPS, but not fNLLP, was completely blocked by lowering the temperature to 19 degrees C, a procedure that prevents vesicle fusion. These studies indicated that an event with the time and temperature dependence of endocytosis precedes signaling by LPS. Cytochalasin D, an inhibitor of phagocytosis, and wortmannin, an inhibitor of phosphatidylinositol 3-kinase that blocks vesicle fusion and phagocytosis, both completely blocked adhesion in response to LPS but not in response to fNLLP. These results support the idea that LPS internalization and early endosomal fusion may be required for signal transduction. Parallel studies showed that the adhesion response to TNF had time, temperature, and inhibitor sensitivities nearly identical with those of LPS, suggesting that responses to TNF may also include an obligate vesicle fusion step.

Cell Adhesion↗
PubMed1996

Peptide G, containing the binding site of the 67-kDa laminin receptor, increases and stabilizes laminin binding to cancer cells.

We investigated the effect of peptide G, a synthetic peptide derived from the sequence of the 37-kDa laminin receptor precursor, on the interaction of laminin in two tumor cell lines one of which produces laminin and one of which does not. Addition of peptide G to the culture medium induced a significant increase in the amount of endogenous laminin detectable on the cell membrane of both cell lines. Moreover, pretreatment of exogenous laminin with peptide G dramatically increased laminin binding on both cell lines. Kinetics analysis of membrane-bound labeled laminin revealed a 3-fold decrease in the kd of peptide G-treated laminin compared with untreated or unrelated or scrambled peptide-treated laminin. Moreover, the affinity constant of peptide G-treated laminin increased 2-fold, with a doubling of the number of laminin binding sites, as determined by Scatchard analysis. Expression of the VLA6 integrin receptor on the cell membrane increased after incubation with peptide G-treated laminin. However, the lower binding inhibition of peptide G-treated laminin after anti-VLA6 antibody or cation chelation treatment indicates that membrane molecules in addition to integrin receptors are involved in the recognition of peptide G-modified laminin. These "new" laminin-binding proteins also mediated cell adhesion to laminin, the first step in tumor invasion. Together, the data suggest that peptide G increases and stabilizes laminin binding on tumor cells, involving surface receptors that normally do not take part in this interaction. This might explain the abundant clinical and experimental data suggesting a key role for the 67-kDa laminin receptor in the interaction between cancer cells and the basement membrane glycoprotein laminin during tumor invasion and metastasis.

Cell Adhesion↗
PubMed1996

A differential role for cell shape in neutrophil tethering and rolling on endothelial selectins under flow.

We investigated the role of neutrophil microvilli in interactions with E-selectin and P-selectin in hydrodynamic shear flow by disruption with cytochalasin B, hypotonic swelling, and chilling. Cytochalasin B only marginally reduced microvilli numbers (from 30 +/- 6 to 16 +/- 6 per cell perimeter, p < 0.005) as shown by electron microscopy, completely disrupted tethering in shear flow to E-selectin and P-selectin, increased the strength of rolling adhesions on E-selectin and P-selectin, and increased cell deformability in shear flow with a likely increase in the area of cell:substrate contact. Hypoosmotic swelling markedly reduced microvilli number (to 6 +/- 5 per perimeter, p < 0.005), almost completely inhibited tethering on E- and P-selectin, and increased the strength of rolling adhesions on P-selectin but not on E-selectin. Chilling almost completely abolished microvilli (to 3 +/- 3 per perimeter, p < 0.005), but pseudopod-like structures were present, and had little effect on tethering in flow. Immunogold labeling of L-selectin, which is normally clustered on tips of microvilli, showed that in the absence of microvilli it remained in small clusters. Our studies show that alterations in cell morphology and viscoelasticity can have opposing effects on tethering and rolling, showing that they are independently regulatable. Furthermore, our results suggest that the association of molecules that mediate rolling with microvilli tips may be important not just to enhance presentation, but for other functions such as to promote resistance to extraction from the membrane or cooperative interactions among clustered receptors.

Cell Adhesion↗