Involvement of lysophosphatidic acid, sphingosine 1-phosphate and ceramide 1-phosphate in the metabolization of phosphatidic acid by lipid phosphate phosphatases in bovine rod outer segments.
The aim of the present research was to evaluate the generation of [2-3H]diacylglycerol ([2-3H]DAG) from [2-3H]-Phosphatidic acid ([2-3H]PA) by lipid phosphate phosphatases (LPPs) at different concentrations of lysophosphatidic acid (LPA), sphingosine 1-phosphate (S1P), and ceramide 1-phosphate (C1P) in purified ROS obtained from dark-adapted retinas (DROS) or light-adapted retinas (BLROS) as well as in ROS membrane preparations depleted of soluble and peripheral proteins. Western blot analysis revealed the presence of LPP3 exclusively in all membrane preparations. Immunoblots of entire ROS and depleted ROS did not show dark-light differences in LPP3 levels. LPPs activities were diminished by 53% in BLROS with respect to DROS. The major competitive effect on PA hydrolysis was exerted by LPA and S1P in DROS and by C1P in BLROS. LPPs activities in depleted ROS were similar to the activity observed in entire DROS and BLROS, respectively. LPA, S1P and C1P competed at different extent in depleted DROS and BLROS. Sphingosine and ceramide inhibited LPPs activities in entire and depleted DROS. Ceramide also inhibited LPPs activities in entire and in depleted BLROS. Our findings are indicative of a different degree of competition between PA and LPA, S1P and C1P by LPPs depending on the illumination state of the retina.
Pasquaré
Susana J
SJ
Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C.C. 857, B8000FWB, Bahia Blanca, Buenos Aires, Argentina.
Salvador
Gabriela A
GA
Giusto
Norma Maria
NM
D000221:Adaptation, Ocular / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D002021:Buffers; D002417:Cattle; D002469:Cell Separation; D002518:Ceramides / Q000378:metabolism / Q000502:physiology*; D003623:Dark Adaptation / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D006868:Hydrolysis; D008246:Lysophospholipids / Q000502:physiology*; D010711:Phosphatidate Phosphatase / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012374:Rod Cell Outer Segment / Q000201:enzymology / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000502:physiology
D002021:Buffers; D002518:Ceramides; D008246:Lysophospholipids; D010712:Phosphatidic Acids; D017382:Reactive Oxygen Species; C065576:ceramide 1-phosphate; C060506:sphingosine 1-phosphate; C112948:lipid phosphate phosphatase; D010711:Phosphatidate Phosphatase; D013110:Sphingosine; C032881:lysophosphatidic acid