The acetaminophen-derived bioactive N-acylphenolamine AM404 inhibits NFAT by targeting nuclear regulatory events.
ABSTRACT AM404 is a synthetic TRPV1/CB(1) hybrid ligand with inhibitory activity on the anandamide transporter and is used for the pharmacological manipulation of the endocannabinoid system. It has been recently described that acetaminophen is metabolised in the brain to form the bioactive N-acylphenolamine AM404 and therefore, we have evaluated the effect of this metabolite in human T cells, discovering that AM404 is a potent inhibitor of TCR-mediated T-cell activation. Moreover, we found that AM404 specifically inhibited both IL-2 and TNF-alpha gene transcription and TNF-alpha synthesis in CD3/CD28-stimulated Jurkat T cells in a FAAH independent way. To further characterize the biochemical inhibitory mechanisms of AM404, we examined the signaling pathways that regulate the activation of the transcription factors NF-kappaB, NFAT and AP-1 in Jurkat cells. We found that AM404 inhibited both the binding to DNA and the transcriptional activity of endogenous NFAT and the transcriptional activity driven by the over expressed fusion protein Gal4-NFAT (1-415). However, AM404 did not affect early steps in NFAT signaling such as CD3-induced calcium mobilization and NFAT1 dephosphorylation. The NFAT inhibitory activity of AM404 seems to be quite specific since this compound did not interfere with the signaling pathways leading to AP-1 or NF-kappaB activation. These findings provide new mechanistic insights into the immunological effects of AM404 which in part could explain some of the activities ascribed to the widely used acetaminophen.
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ABSTRACT: Despite nearing the end of the decade of pain research, the analgesic mechanisms of one of the most widely used and popular analgesics remains uncertain. Acetaminophen (APAP) (paracetamol [PARA]) has been used clinically for over a half of a century and although clinicians seem to be comfortable with its benefits, risks, and limitations, they still remain in the dark as to precisely what is providing its pain relief. What does seem clearer is that the predominant mechanisms of APAP's analgesic effects are in the central nervous system (CNS). Although, which central effects are largely responsible for APAP's effects on pain continue to be uncertain. Perhaps, the most accepted theory is that of APAP's positive effects on the serotonergic descending inhibitory pathways. However, interactions with opioidergic systems, eicosanoid systems, and/or nitric oxide containing pathways may be involved as well. Furthermore, endocannabinoid signaling may play a role in APAP's activation of the serotonergic descending inhibitory pathways. A greater understanding of APAP's analgesic mechanisms may promote optimal utilization of analgesic polypharmacy.Pain physician 12(1):269-80. · 10.72 Impact Factor