Stretching Mesangial Cells Stimulates Tyrosine Phosphorylation of Focal Adhesion Kinase pp125FAK

1995 ◽  
Vol 212 (2) ◽  
pp. 544-549 ◽  
Author(s):  
K. Hamasaki ◽  
T. Mimura ◽  
H. Furuya ◽  
N. Morino ◽  
T. Yamazaki ◽  
...  
Keyword(s):  
Focal Adhesion Kinase ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
Mesangial Cells

scholarly journals Tyrosine phosphorylation of focal adhesion kinase (p125FAK): regulation by cAMP and thrombin in mesangial cells.

1996 ◽  
Vol 7 (3) ◽  
pp. 415-423
Author(s):  
D A Troyer ◽  
A Bouton ◽  
R Bedolla ◽  
R Padilla
Keyword(s):  
Focal Adhesion Kinase ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
Actin Filaments ◽  
Mesangial Cells ◽  
Close Contact ◽  
Focal Adhesions ◽  
Cytochalasin D ◽  
Fiber Formation ◽  
Stress Fibers

Stress fibers, composed of actin filaments, converge upon and associate with a number of proteins, including focal adhesion kinase (p125FAK), and integrin receptors to form areas of close contact between cells and the extracellular matrix referred to as focal adhesions. Treatment of mesangial cells with cAMP-elevating agents causes a loss of focal adhesions, fragmentation of stress fibers, and decreased tyrosine phosphorylation of p125FAK. Thrombin reverses these effects of cAMP, and this model can be used to address some of the cellular mechanisms involved in regulating the loss and formation of focal adhesions. This study reports the effects of cAMP and thrombin on mesangial cell shape, distribution of actin, formation of stress fibers, and tyrosine phosphorylation of p125FAK. cAMP-treated cells display a condensed cell body with slender processes that traverse the area formerly covered by the cell. Addition of thrombin to these cells restores actin filaments (stress fibers) and increases tyrosine phosphorylation of p125FAK, and the cells resume a flattened morphology, even in the continued presence of cAMP-elevating agents. Peptides that mimic the tethered ligand portion of the thrombin receptor have the same effects on cell morphology and stress fiber formation as thrombin. In selected experiments, agents that disrupt either stress fibers (cytochalasin D) or microtubules (nocodazole; Sigma Chemical, St. Louis, MO) were used to examine the role of these cytoskeletal elements in thrombin-induced restoration of focal adhesions. Cytochalasin D blocked the ability of thrombin to restore focal adhesions and phosphorylate p125FAK. The effects of nocodazole, an agent that destabilizes microtubules (but which has no known receptor), are very similar to those of thrombin. The findings discussed in this study indicate that thrombin can modulate the formation of focal adhesions. The organization of stress fibers and microtubules is apparently intimately related to the phosphorylation of p125FAK and can be modulated by soluble receptor agonists such as thrombin or via altered polymerization of microtubules.

scholarly journals Endothelin-1 stimulates tyrosine phosphorylation of p125 focal adhesion kinase in mesangial cells.

1995 ◽  
Vol 6 (5) ◽  
pp. 1504-1510
Author(s):  
M Haneda ◽  
R Kikkawa ◽  
D Koya ◽  
T Shikano ◽  
T Sugimoto ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Tyrosine Kinase ◽  
Focal Adhesion Kinase ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
Protein Tyrosine Kinase ◽  
Mesangial Cells ◽  
Glomerular Mesangial Cells ◽  
Protein Tyrosine ◽  
Endothelin 1

Endothelin-1 (ET-1) is known to induce the contraction and proliferation of glomerular mesangial cells. Because ET-1 was found to stimulate the tyrosine phosphorylation of unidentified cellular proteins in cultured mesangial cells, protein tyrosine kinase might serve as one of the important signals leading to various functions of ET-1. Focal adhesion kinase (p125FAK) is a newly identified cytoplasmic protein tyrosine kinase that is activated by the phosphorylation of its own tyrosine residue. Because p125FAK was found to play a role in the signal transduction of not only integrins but also various neurotransmitters, including bombesin, endothelin, and vasopressin in Swiss 3T3 cells and Rat-1 fibroblasts, whether ET-1 could stimulate the tyrosine phosphorylation of p125FAK in glomerular mesangial cells was examined. ET-1 stimulated the tyrosine phosphorylation of p125FAK by threefold to fourfold in cultured mesangial cells. This effect of ET-1 was detected at 1 min and reached a maximum within 5 min and was blocked by BQ-123, an antagonist for ETA receptor. A23187, a calcium ionophore, failed to stimulate the tyrosine phosphorylation of p125FAK, and ET-1 was able to stimulate the tyrosine phosphorylation of p125FAK, even in a calcium-free medium. The activation of protein kinase C (PKC) by phorbol 12, 13-dibutyrate resulted in a stimulation of the tyrosine phosphorylation of p125FAK, and an inhibition of PKC by calphostin C or staurosporine significantly reduced the effect of ET-1. Furthermore, prolonged treatment of the cells with phorbol 12, 13-dibutyrate markedly inhibited the ET-1-induced tyrosine phosphorylation of p125FAK. These results indicate that p125FAK might play a role in a signal transduction system of ET-1 in glomerular mesangial cells and that the ET-1-induced tyrosine phosphorylation of p125FAK is largely dependent on the PKC pathway.

Expression of β1 integrins in glomerular tissue of Streptozotocin-induced diabetic rats

1999 ◽  
Vol 77 (1) ◽  
pp. 71-78 ◽  
Author(s):  
Mari Regoli ◽  
Moïse Bendayan
Keyword(s):  
Extracellular Matrix ◽  
Focal Adhesion Kinase ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
Plasma Membranes ◽  
Mesangial Cells ◽  
Diabetic Rats ◽  
Morphological Alteration ◽  
Western Blots ◽  
Extracellular Matrix Components

Based upon the importance of integrins as receptors for extracellular matrix components as well as transducers of extracellular signals, and since major alterations take place in the renal extracellular matrix during diabetes, it is important to study the role played by integrins in the development of the diabetic glomerulosclerosis. Expression of the β1 subunit by renal glomerular cells was evaluated by biochemical and morphological means in short- and long-term diabetic rats. Western blots of isolated rat renal glomeruli demonstrated that the expression of β1 increases along with age as well as with the hyperglycaemic state. These changes were significant as early as 6 weeks of hyperglycaemia. This was further demonstrated by immunocytochemistry, which revealed the presence of the β1 subunit at the level of the plasma membranes of endothelial, epithelial, and mesangial cells. Quantitation of the immunolabelings confirmed the increased expression of β1 under diabetic conditions. Further to this, expression of the focal adhesion kinase (FAK) was evaluated by immunoblotting showing little increase in diabetic conditions. On the other hand, testing the tyrosine phosphorylation of FAK, revealed significant increases in diabetes. To recover the fraction of FAK associated with the β1 subunit, immunoprecipitation of isolated glomeruli homogenates was carried out with the anti- β1 antibody. This demonstrated that the amounts of FAK co-precipitated with β1, as well as its tyrosine-phosphorylation, are in fact reduced in diabetic conditions. Since the changes reported were observed at time points prior to any morphological alteration of the renal extracellular matrix, it appears that modifications in integrins and in their intracellular relays constitute early events that precede the onset of the diabetic nephropathy and must then be associated with the hyperglycaemic condition.Key words: integrins, focal adhesion kinase, tyrosine phosphorylation, renal tissue, diabetes.

scholarly journals Candida albicans Expresses a Focal Adhesion Kinase-Like Protein That Undergoes Increased Tyrosine Phosphorylation upon Yeast Cell Adhesion to Vitronectin and the EA.hy 926 Human Endothelial Cell Line

2002 ◽  
Vol 70 (7) ◽  
pp. 3804-3815 ◽  
Author(s):  
Giorgio Santoni ◽  
Roberta Lucciarini ◽  
Consuelo Amantini ◽  
Jordan Jacobelli ◽  
Elisabetta Spreghini ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Candida Albicans ◽  
Cell Adhesion ◽  
Endothelial Cell ◽  
Yeast Cell ◽  
Focal Adhesion Kinase ◽  
Cell Line ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
Human Endothelial Cell Line

ABSTRACT The signaling pathways triggered by adherence of Candida albicans to the host cells or extracellular matrix are poorly understood. We provide here evidence in C. albicans yeasts of a p105 focal adhesion kinase (Fak)-like protein (that we termed CaFak), antigenically related to the vertebrate p125Fak, and its involvement in integrin-like-mediated fungus adhesion to vitronectin (VN) and EA.hy 926 human endothelial cell line. Biochemical analysis with different anti-chicken Fak antibodies identified CaFak as a 105-kDa protein and immunofluorescence and cytofluorimetric analysis on permeabilized cells specifically stain C. albicans yeasts; moreover, confocal microscopy evidences CaFak as a cytosolic protein that colocalizes on the membrane with the integrin-like VN receptors upon yeast adhesion to VN. The protein tyrosine kinase (PTK) inhibitors genistein and herbimycin A strongly inhibited C. albicans yeast adhesion to VN and EA.hy 926 endothelial cells. Moreover, engagement of αvβ3 and αvβ5 integrin-like on C. albicans either by specific monoclonal antibodies or upon adhesion to VN or EA.hy 926 endothelial cells stimulates CaFak tyrosine phosphorylation that is blocked by PTK inhibitor. A role for CaFak in C. albicans yeast adhesion was also supported by the failure of VN to stimulate its tyrosine phosphorylation in a C. albicans mutant showing normal levels of CaFak and VNR-like integrins but displaying reduced adhesiveness to VN and EA.hy 926 endothelial cells. Our results suggest that C. albicans Fak-like protein is involved in the control of yeast cell adhesion to VN and endothelial cells.

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