Coexistence of phosphatidylcholine-specific phospholipase C and phospholipase D activities in rat cerebral cortex synaptosomes.
DAG derived from phosphatidylcholine (PtdCho) acts as a lipid second messenger. It can be generated by the activation of phospholipase D (PLD) and the phosphatidic acid phosphohydrolase type 2 (PAP2) pathway or by a PtdCho-specific phospholipase C (PtdCho-PLC). Our purpose was to study PtdCho-PLC activity in rat cerebral cortex synaptosomes (CC Syn). DAG production was highly stimulated by detergents such as Triton X-100 and sodium deoxycholate. Ethanol and tricyclodecan-9-yl-xanthate potassium salt decreased DAG generation by 42 and 61%, respectively, at 20 min of incubation. These data demonstrate that both the PLD/PAP2 pathway and PtdCho-PLC contribute to DAG generation in CC Syn. PtdCho-PLC activity remained located mainly in the synaptosomal plasma membrane fraction. Kinetic studies showed Km and Vmax values of 350 microM and 3.7 nmol DAG x (mg protein x h)(-1), respectively. Western blot analysis with anti-PtdCho-PLC antibody showed a band of 66 KDa in CC Syn. Our results indicate the presence of a novel DAG-generating pathway in CC Syn in addition to the known PLD/PAP2 pathway.
Mateos
Melina V
MV
Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, CC 857, B8000FWB Bahía Blanca, Argentina.
Uranga
Romina M
RM
Salvador
Gabriela A
GA
Giusto
Norma M
NM
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism* / Q000648:ultrastructure; D003902:Detergents / Q000494:pharmacology; D008071:Lipoprotein Lipase / Q000378:metabolism*; D010711:Phosphatidate Phosphatase / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D013574:Synaptosomes / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism*
D003902:Detergents; D010713:Phosphatidylcholines; D008071:Lipoprotein Lipase; D010711:Phosphatidate Phosphatase; D010738:Type C Phospholipases; D010739:Phospholipase D