Jeffery J. Prusakiewicz

Oxidative Metabolism of Endocannabinoids by COX-2

The last decade has witnessed a rapid expansion in our understanding of the mammalian endogenous cannabinoid system. In just a few short years since the discovery of endogenous lipids that serve as cannabinoids in vivo, these molecules have been shown to participate in a broad array of physiological and pathological processes. Consequently, attention has been directed at defining the proteins responsible for endocannabinoid synthesis, transport, and metabolism. Recently, multiple fatty acid oxygenases including, most notably, cyclooxygenase-2 (COX-2), have been implicated in endocannabinoid metabolism. This review will highlight connections between COX-2 and the endogenous cannabinoid system. The available biochemical evidence supporting a role for COX-2 in endocannabinoid metabolism will be presented. Finally, the potential biological consequences of COX-2-mediated endocannabinoid oxygenation will be discussed.

(R)-Profens are substrate-selective inhibitors of endocannabinoid oxygenation by COX-2

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Professional editors thus effectively prescreen papers by acting not only as scientists but also as advocates of the scientific readership, considering papers in several dimensions in an effort to ensure that all papers published in the journal will be required reading for the field. How do we ‘screen’ papers? Contrary to suggestions that professional editors are indecisive and act merely as managers (Nature 472, 391, 2011), editors can only be effective if they form thoughtful opinions and act accordingly. Beyond the initial evaluation, in which editors must be able to enumerate the strengths of a particular manuscript, editors take an active role in managing the peer review process. As with academic editors, professional editors rely on referees to evaluate the technical merits of a manuscript, weigh in on whether the experimental evidence supports the major conclusions of a study and provide advice as to whether the findings are sufficient to merit publication in the journal (Nat. 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At Nature Chemical Biology, we continually challenge ourselves to keep connected with current research and be mindful of the evolution of the fields we cover. We strive to make our decisions timely and transparent for authors so that, even if they are unsuccessful with one submission, the insight they gain into our processes could benefit future submissions. Finally, we are aware that publishing models continually evolve (Nat. Chem. Biol. 2, 391, 2006), and we seek opportunities for improving the publishing process through the open dialogue we consistently pursue with our authors, referees and readers. ◾ Professional editors provide the perspective, consistency and responsiveness needed to identify and communicate groundbreaking scientific advances. Our professional opinion

Differential Sensitivity and Mechanism of Inhibition of COX-2 Oxygenation of Arachidonic Acid and 2-Arachidonoylglycerol by Ibuprofen and Mefenamic Acid

Ibuprofen and mefenamic acid are weak, competitive inhibitors of cyclooxygenase-2 (COX-2) oxygenation of arachidonic acid (AA) but potent, noncompetitive inhibitors of 2-arachidonoylglycerol (2-AG) oxygenation. The slow, tight-binding inhibitor, indomethacin, is a potent inhibitor of 2-AG and AA oxygenation whereas the rapidly reversible inhibitor, 2′-des-methylindomethacin, is a potent inhibitor of 2-AG oxygenation but a poor inhibitor of AA oxygenation. These observations are consistent with a model in which inhibitors bind in one subunit of COX-2 and inhibit 2-AG binding in the other subunit of the homodimeric protein. In contrast, ibuprofen and mefenamate must bind in both subunits to inhibit AA binding.

Selective oxygenation of N-arachidonylglycine by cyclooxygenase-2

Nonsteroidal anti-inflammatory drugs prevent hyperalgesia and inflammation by inhibiting the cyclooxygenase-2 (COX-2) catalyzed oxygenation of arachidonic acid to prostaglandin (PG) H(2). The lipoamino acid N-arachidonylglycine (NAGly) has also been shown to suppress tonic inflammatory pain and is naturally present at significant levels in many of the same mammalian tissues that express COX-2. Here, we report that COX-2 selectively metabolizes NAGly to PGH(2) glycine (PGH(2)-Gly) and hydroxyeicosatetraenoic glycine (HETE-Gly). Site-directed mutagenesis experiments identify the side pocket residues of COX-2, especially Arg-513, as critical determinants of the COX-2 selectivity towards NAGly. This is the first report of a charged arachidonyl derivative that is a selective substrate for COX-2. These results suggest a possible role for COX-2 in the regulation of NAGly levels and the formation of a novel class of eicosanoids from NAGly metabolism.

Enantiospecific, selective cyclooxygenase-2 inhibitors.

Cyclooxygenase inhibition studies with novel indomethacin alkanolamides demonstrate the potential for dramatic differences in inhibitor properties conferred by subtle structural modifications. The transformation of non-selective alpha-(S)-substituted indomethacin ethanolamides to potent, COX-2 selective inhibitors by simple stereocenter inversion highlights this property.

Conservative Secondary Shell Substitution In Cyclooxygenase-2 Reduces Inhibition by Indomethacin Amides and Esters via Altered Enzyme Dynamics.

The cyclooxygenase enzymes (COX-1 and COX-2) are the therapeutic targets of nonsteroidal anti-inflammatory drugs (NSAIDs). Neutralization of the carboxylic acid moiety of the NSAID indomethacin to an ester or amide functionality confers COX-2 selectivity, but the molecular basis for this selectivity has not been completely revealed through mutagenesis studies and/or X-ray crystallographic attempts. We expressed and assayed a number of divergent secondary shell COX-2 active site mutants and found that a COX-2 to COX-1 change at position 472 (Leu in COX-2, Met in COX-1) reduced the potency of enzyme inhibition by a series of COX-2-selective indomethacin amides and esters. In contrast, the potencies of indomethacin, arylacetic acid, propionic acid, and COX-2-selective diarylheterocycle inhibitors were either unaffected or only mildly affected by this mutation. Molecular dynamics simulations revealed identical equilibrium enzyme structures around residue 472; however, calculations indicated that the L472M mutation impacted local low-frequency dynamical COX constriction site motions by stabilizing the active site entrance and slowing constriction site dynamics. Kinetic analysis of inhibitor binding is consistent with the computational findings.