کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1948735 1054708 2006 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Sodium orthovanadate induced tyrosine phosphorylation of platelet nitric oxide synthase negatively regulates enzyme activity
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Sodium orthovanadate induced tyrosine phosphorylation of platelet nitric oxide synthase negatively regulates enzyme activity
چکیده انگلیسی

The post-translational regulation of platelet nitric oxide synthase (NOS) activity is poorly understood. In the present study we examined how tyrosine phosphorylation of NOS, induced by the tyrosine phosphatase inhibitor sodium orthovanadate (VO4), influenced enzyme activity. Platelet NOS was basally tyrosine phosphorylated, but incubation with VO4 (100–1000 μM) led to a concentration-dependent increase in tyrosine phosphorylation of the enzyme with maximal effects observed at 500 μM. Importantly, we observed no change in serine1179 or threonine497 phosphorylation. The increased tyrosine phosphorylation was associated with reduced NOS activity and NO bioavailability, as evidenced by measurement of [3H]-l-citrulline and cGMP respectively. The signalling events underlying the effects of VO4 were studied using specific inhibitors to kinases that are known to influence NOS activity. Preincubation of platelets with the Src kinase inhibitor PP2 (20 μM) blocked VO4-induced tyrosine phosphorylation of NOS and abolished the effects of VO4 on cGMP formation. The PKC inhibitor Ro-31-8220 (10 μM) had no effect on VO4-induced tyrosine phosphorylation, but did have a modest but significant effect on cGMP formation. In contrast, the PI-3-kinase inhibitor wortmannin (100 nM) had no effect on either tyrosine phosphorylation or cGMP formation. Our data indicate that tyrosine phosphorylation may act to repress NOS activity. Furthermore, VO4 induces a Src-dependent, and to a lesser degree PKC-dependent, inhibition of platelet NOS.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Biochimica et Biophysica Acta (BBA) - General Subjects - Volume 1760, Issue 9, September 2006, Pages 1411–1417
نویسندگان
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