Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pathogenesis of nonalcoholic steatohepatitis (NASH) is unclear, despite epidemiological data implicating FFAs. We studied the pathogenesis of NASH using lipoapoptosis models. Palmitic acid (PA) induced classical apoptosis of hepatocytes. PA-induced lipoapoptosis was inhibited by acyl-CoA synthetase inhibitor but not by ceramide synthesis inhibitors, suggesting that conversion products other than ceramide are involved. Phospholipase A(2) (PLA(2)) inhibitors blocked PA-induced hepatocyte death, suggesting an important role for PLA(2) and its product lysophosphatidylcholine (LPC). Small interfering RNA for Ca(2+)-independent phospholipase A(2) (iPLA(2)) inhibited the lipoapoptosis of hepatocytes. PA increased LPC content, which was reversed by iPLA(2) inhibitors. Pertussis toxin or dominant-negative Galpha(i) mutant inhibited hepatocyte death by PA or LPC acting through G-protein-coupled receptor (GPCR)/Galpha(i). PA decreased cardiolipin content and induced mitochondrial potential loss and cytochrome c translocation. Oleic acid inhibited PA-induced hepatocyte death by diverting PA to triglyceride and decreasing LPC content, suggesting that FFAs lead to steatosis or lipoapoptosis according to the abundance of saturated/unsaturated FFAs. LPC administration induced hepatitis in vivo. LPC content was increased in the liver specimens from NASH patients. These results demonstrate that LPC is a death effector in the lipoapoptosis of hepatocytes and suggest potential therapeutic values of PLA(2) inhibitors or GPCR/Galpha(i) inhibitors in NASH.
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PMID:Lysophosphatidylcholine as a death effector in the lipoapoptosis of hepatocytes. 1795 Dec 22

Kinetic methods in unanesthetized rodents have shown that turnover rates of arachidonic acid (AA) and docosahexaenoic acid (DHA) in brain membrane phospholipids are rapid and energy consuming and that phospholipase A(2) (PLA(2)) and acyl-CoA synthetase enzymes that regulate turnover are specific for one or the other PUFA. Thus, AA turnover in brain phospholipids was reduced, and AA-selective cytosolic cPLA(2) or acyl-CoA synthetase, as well as cyclooxygenase (COX)-2, were downregulated in brains of rats given drugs effective against bipolar disorder, whereas DHA turnover and expression of DHA-selective calcium-independent iPLA(2) were unchanged. Additionally, the brain AA and DHA cascades can be altered reciprocally by dietary or genetic conditions. Thus, following 15 wk of dietary (n-3) PUFA deprivation, DHA loss from rat brain was slowed because of reduced iPLA(2) and COX-1 expression, whereas AA-selective cPLA(2), sPLA(2), and COX-2 were upregulated, as were AA and docosapentaenoic acid concentrations. Measured rates of AA and DHA incorporation into brain represent their respective rates of metabolic consumption, because these PUFA are not synthesized de novo or converted significantly from their precursors in brain. In healthy human volunteers, positron emission tomography (PET) was used to show that the brain consumes AA and DHA at respective rates of 17.8 and 4.6 mg/d, whereas in patients with Alzheimer disease, AA consumption is elevated. In the future, PET could be used to relate human brain rates of AA and DHA consumption to liver PUFA metabolism and dietary PUFA intake.
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PMID:Arachidonic acid and the brain. 1902 81