caa a22 4500 397557264 CHVBK 20180308164806.0 cr unu---uuuuu 161202e199607 xx s 000 0 eng 10.1093/oxfordjournals.jbchem.a021394 doi (NATIONALLICENCE)oxford-10.1093/oxfordjournals.jbchem.a021394 Sphingosine Enhances Phosphatidylinositol 4-Kinase Activity in Rabbit Platelets [Elektronische Daten] [Tsutomu Hashizume, Masahiko Nakao, Takashi Sato] The modulating effect of sphingosine on the metabolism of inositol phospholipids was investigated using rabbit platelets. When [3H]arachidonic acid- or [3H] inositol-labeled platelets were incubated at 37°C with sphingosine, the radioactivity of the phosphatidylinositol (PI) fraction obtained on TLC decreased time-dependently up to 5min, and phosphatidylinositol monophosphate (PIP) and phosphatidylinositol bisphosphate (PIP2) increased concomitantly, though neither arachidonic acid nor 1,2-diacylglycerol was formed. The effect of sphingosine was dose-dependent, the maximum effect being observed at 20 μM. Treatment with a sphingosine derivative, sphingosine-1-phosphate (Sph-1-P) or N-hexanoyl-sphingosine (C6-ceramide), did not result in an increase in PIP. The increased radioactivity of PEP with sphingosine was attributable to an increase in phosphatidylinositol 4-phosphate, but not phosphatidylinositol 3-phosphate. Furthermore, wortman-nin, an inhibitor of PI 3-kinase, did not affect the modulating effect of sphingosine at 100 nM, at which the enzyme is known to be completely inhibited. The activity of PI 4-kinase in the platelet lysate was increased by sphingosine but not by Sph-l-P. These results suggest that sphingosine enhances the activity of PI 4-kinase and thereby contributes to the regulation of inositol phospholipid metabolism. © 1996 BY THE JOURNAL OF BIOCHEMISTRY Regular Papers nationallicence phosphatidylinositol 4-kinase nationallicence phosphatidylinositol 4-phosphate nationallicence platelet nationallicence platelet nationallicence sphingosine nationallicence Hashizume Tsutomu Department of Pathological Biochemistry, Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607 aut Nakao Masahiko Department of Pathological Biochemistry, Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607 aut Sato Takashi Department of Pathological Biochemistry, Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607 aut The Journal of Biochemistry Oxford University Press 120/1(1996-07), 61-65 0021-924X 120:1<61 1996 120 jbchem https://doi.org/10.1093/oxfordjournals.jbchem.a021394 text/html Onlinezugriff via DOI 1 other jats NATIONALLICENCE 856 40 https://doi.org/10.1093/oxfordjournals.jbchem.a021394 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hashizume Tsutomu Department of Pathological Biochemistry, Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607 aut NATIONALLICENCE 700 1- Nakao Masahiko Department of Pathological Biochemistry, Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607 aut NATIONALLICENCE 700 1- Sato Takashi Department of Pathological Biochemistry, Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607 aut NATIONALLICENCE 773 0- The Journal of Biochemistry Oxford University Press 120/1(1996-07), 61-65 0021-924X 120:1<61 1996 120 jbchem Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford