Stimulation of Tetrahydrobiopterin Synthesis by Basic Fibroblast Growth Factor in Vascular Endothelial Cells

Pteridines ◽  
2003 ◽  
Vol 14 (1) ◽  
pp. 9-12 ◽  
Author(s):  
Shunichi Shimizu ◽  
Yoshiyuki Miyasaka ◽  
Shinichiro Yamamoto ◽  
Masakazu Ishii ◽  
Yuji Kiuchi

Abstract The purpose of this study was to examine whether basic fibroblast growth factor (bFGF) stimulates tetrahydrobiopterin (BH4) synthesis in mouse brain microvascular endothelial cells. BH4 content was determined by oxidation under acidic conditions as biopterin and analysed with reversed-phase high Performance liquid chromatography. Measurement of the mRNA level of QTP-cyclohydrolase I (GTPCH), which is the rate-limiting enzyme of the de novo pathway of BH4 synthesis. The addition of bFGF to endothelial cells increased the BH4 content and GTPCH mRNA levels in an incubation period- and a concentration-dependent manner. 2,4-Diamino-6- hydroxypyrimidine, an inhibitor of GTPCH, strongly reduced the bFGF-induced increase in BH4 content. These findings suggest that bFGF stimulates BH4 synthesis via a de novo pathway with the induction of GTPCH.

1999 ◽  
Vol 10 (9) ◽  
pp. 2933-2943 ◽  
Author(s):  
Susanne Schenk ◽  
Ruth Chiquet-Ehrismann ◽  
Edouard J. Battegay

To investigate the potential role of tenascin-C (TN-C) on endothelial sprouting we used bovine aortic endothelial cells (BAECs) as an in vitro model of angiogenesis. We found that TN-C is specifically expressed by sprouting and cord-forming BAECs but not by nonsprouting BAECs. To test whether TN-C alone or in combination with basic fibroblast growth factor (bFGF) can enhance endothelial sprouting or cord formation, we used BAECs that normally do not sprout and, fittingly, do not express TN-C. In the presence of bFGF, exogenous TN-C but not fibronectin induced an elongated phenotype in nonsprouting BAECs. This phenotype was due to altered actin cytoskeleton organization. The fibrinogen globe of the TN-C molecule was the active domain promoting the elongated phenotype in response to bFGF. Furthermore, we found that the fibrinogen globe was responsible for reduced cell adhesion of BAECs on TN-C substrates. We conclude that bFGF-stimulated endothelial cells can be switched to a sprouting phenotype by the decreased adhesive strength of TN-C, mediated by the fibrinogen globe.


1998 ◽  
Vol 35 (5) ◽  
pp. 363-371 ◽  
Author(s):  
Johannes Wiecha ◽  
Benedikt Münz ◽  
Yongjian Wu ◽  
Thomas Noll ◽  
Harald Tillmanns ◽  
...  

1987 ◽  
Author(s):  
O Saksela ◽  
D Moscatelli ◽  
D B Rifkin

Basic fibroblast growth factor (bFGF), a potent inducer of angio-genesis in vivo, stimulates the production of both the cell-associated and the secreted forms of urokinase-and tissue-type plasminogen activators (PA) in cultured bovine capillary endothelial cells. This stimulation was counteracted by picogram amounts of transforming growth factor beta The stimulatory effect of bFGF was not completely abolished by increasing the amount of TGFb However, the inhibition by TGFb was greatly enhanced if the cells were pretreated for 1-3 hours with TGFb before addition of bFGF, and the inhibition was almost total, if the' preincubationtime with TGFb was 6 hours.Sequential chanqes of serum-containing medium prior to addition ofbFGF also blocked the PA stimulatory effect of bFGF. This inhibitory activity of serum was reduced by incubation of the serum with anti-TGFb-IgG. After pro-longed incubation of cultures treated simultaneously with bFGF' and TGFb, the inhibitory effect of the added bFGF dominated as assayed by PAlevels. TGFbdid not alter the receptor binding of labeled bFGF, nor did a 6 hour pretreatment with TGFb reducethe amount of bound bFGF. The major difference between effects by bFGF and TGFb was thatwhile bFGF effectively enhanced PA-activi-ty expressed by the cells, TGF decreased the amounts of both cell-associated and secreted PA activity by decreasing enzyme production and proenzyme activation. Both bFGF and TGFb increased the secretion of the endothelial type 1 plasminogen activatorinhibitor (PAI 1). The highest concentration of TGFb is found in platelets, and it is known to be released during clot formation. The suppression of PA production by theendothelium by the release of TGFb shouldresult in a decrease in the fibrinolytic activity and promote clot maintenance. In addition, the rapid stimulation of high levels of PAI 1 secretion from the surrounding capillarycells by platelet released TGFb may further suppress fibrinolysis'. The reversabil it.y of theTGFb effect and domination of bFGF stimulation may be important in relation to the subsequentonset of clot lysis or angiogenesis leadino to thrombus reorganization and wound healing.


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