Article

A biosynthetic pathway for anandamide

Laboratories of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 10/2006; 103(36):13345-50. DOI: 10.1073/pnas.0601832103
Source: PubMed

ABSTRACT The endocannabinoid arachidonoyl ethanolamine (anandamide) is a lipid transmitter synthesized and released "on demand" by neurons in the brain. Anandamide is also generated by macrophages where its endotoxin (LPS)-induced synthesis has been implicated in the hypotension of septic shock and advanced liver cirrhosis. Anandamide can be generated from its membrane precursor, N-arachidonoyl phosphatidylethanolamine (NAPE) through cleavage by a phospholipase D (NAPE-PLD). Here we document a biosynthetic pathway for anandamide in mouse brain and RAW264.7 macrophages that involves the phospholipase C (PLC)-catalyzed cleavage of NAPE to generate a lipid, phosphoanandamide, which is subsequently dephosphorylated by phosphatases, including PTPN22, previously described as a protein tyrosine phosphatase. Bacterial endotoxin (LPS)-induced synthesis of anandamide in macrophages is mediated exclusively by the PLC/phosphatase pathway, which is up-regulated by LPS, whereas NAPE-PLD is down-regulated by LPS and functions as a salvage pathway of anandamide synthesis when the PLC/phosphatase pathway is compromised. Both PTPN22 and endocannabinoids have been implicated in autoimmune diseases, suggesting that the PLC/phosphatase pathway of anandamide synthesis may be a pharmacotherapeutic target.

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    • "AEA: anandamide, NAPE: N-acylphosphatidylethanolamine, NAPE-PLD: N-acylphosphatidylethanolamine phospholipase D, GDE1: glycerophosphodiester phosphodiesterase 1, ABHD4: í µí»¼/í µí»½ hydrolase domain containing protein 4, PTPN22: protein tyrosine phosphatase nonreceptor type 22, sPLA2: soluble phospholipase A2, INPP5D: inositol 5-phosphatase, PLC: phospholipase C, FAAH: fatty acid amide hydrolase, COX-2: cycloxygenase 2, LOX-12: arachidonate 12-lipoxygenase, LOX-15: arachidonate 15-lipoxygenase, gp- AEA: glycerophosphoanandamide, p-AEA: phospho-anandamide, lysoNAPE: lyso-N-acylphosphatidylethanolamine, AA: arachidonic acid, ETA: ethanolamine, PG: prostaglandins, PM: prostamides, and 12/15-hAEA: 12/15-hydroxyanandamide. phospholipid precursor N-arachidonoylphosphatidylethanolamine (NAPE) through hydrolysis by a N-arachidonoylphosphatidylethanolamine phospholipase D (NAPE-PLD) [27] in a Ca 2+ -sensitive manner, recent evidence [28] indicates the existence of two parallel, additional, phospholipase C (PLC) and secreted phospholipase A2 (sPLA2)—catalyzed, Ca 2+ -independent pathways. The PLC pathway involves PLC itself and two other enzymes with parallel activity: protein tyrosine phosphatase non-receptor type 22 (PTPN22) and phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase 1 (INPP5D) [29] [30]. The sPLA2 pathway also includes the í µí»¼/í µí»½ hydrolase domain containing protein 4 (ABHD4) and glycerophosphodiesterphosphodiesterase 1 (GDE1) [31] (Figure 1). "
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    • "Author's personal copy (NAPE) (Di Marzo et al., 1994; Okamoto, Morishita, Tsuboi, Tonai, & Ueda, 2004). The second pathway mediates anandamide synthesis in mouse brain and RAW264.7 mouse macrophages, in which phospholipase C catalyzes the cleavage of NAPE to produce phosphoanandamide (Liu et al., 2006), which is then dephosphorylated into anandamide by a protein tyrosine phosphatase PTPN22 (Cohen, Dadi, Shaoul, Sharfe, & Roifman, 1999). This pathway is upregulated by endotoxins in macrophages and may be responsible for the hypotension of septic shock and advanced liver cirrhosis (Liu et al., 2006). "
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    • "AEA is synthesized on demand by different pathways, mainly from membrane bound Narachidonoyl phosphatidylethanolamine (NAPE) through cleavage by a phospholipase D (NAPE-PLD) [4]. Its effects finish by the uptake of AEA into the cell followed by a rapid degradation by the enzyme fatty acid amide hydrolase (FAAH) into arachidonic acid and ethanolamine [5]. CB1 and FAAH have been localized in human term placenta tissue [6], and several studies suggest that FAAH protein is crucial for the control of circulating AEA concentrations [7] [8]. "
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