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Lipids as Second Messengers in Cell Signaling Pathways

This article explores the role of lipids in cell signaling, particularly those derived from the arachidonic acid (AA) pathway. Arachidonic acid, an unsaturated fatty acid, is integral to membrane phospholipids and is released by phospholipase A2. Key lipid mediators such as prostaglandins, leukotrienes, and lipoxins are discussed in relation to their synthesis and function. The article highlights how these molecules participate in inflammatory responses and other physiological processes, influenced by enzymes like COX and lipoxygenase.

jaime-randolph
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Lipids as Second Messengers in Cell Signaling Pathways

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  1. Lipids in Cell Signaling SIGMA-ALDRICH

  2. Lipids in Cell Signaling Many of the lipids involved as second messengers in cell signaling pathways arise from the arachidonic acid (AA) pathway. AA is an unsaturated fatty acid that is a normal constituent of membrane phospholipids and is released from the phospholipids by the actions of phospholipase A2 (PLA2). Prostaglandins (PG) arise from a cyclic endoperoxide generated by the enzyme system PG synthetase, a complex of enzymes that includes cyclooxygenase (COX).There is a constitutive (COX-1) and an inducible cyclooxygenase (COX-2). The cyclic endoperoxide intermediate is also a precursor of prostacyclin (PGI2) and thromboxane (TXA3). Other groups of compounds in this class, leukotrienes (LT) and lipoxins (LP), are derived directly from AA without the mediation of a cyclic endoperoxide. Lipoxygenase acts on AA to produce 5-hydroperoxyeicosatetraenoic acid (5-HPETE) that is converted to LTA4. LTA4 is the precursor of LTB4, that induces inflammation by its chemotactic and degranulating actions on polymorphonuclear lymphocytes (PML), and of LTC4, LTD4, and LTE4, the amino acid containing LTs that induce vasoconstriction and bronchoconstriction and are involved in asthma and anaphylaxis. References Heller, A., et al., Lipid mediators in inflammatory disorders. Drugs, 55, 487-496(1998). Cook, J.A., et al., Prostaglandins, thromboxanes, leukotrienes, and cytochrome P-450 metabolites of arachidonic acid. New Horiz., 1, 60-69(1993). Dubois, R.N., et al., Cyclooxygenase in biology and disease. FASEB J., 12, 1063-1073(1998).

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