The Cardiotoxic and Cardioprotective Potential of Cytochrome P450 2J2 (CYP2J2)
Authors: Arnold William R , Baylon Javier , Tajkhorshid Emad , Das Aditi 
Published: November 2023

ObjectiveCharacterizing endogenous and drug substrate interactions with cytochrome P450 2J2 (CYP2J2) in order to understand the impact on cardioprotection and cardiotoxicity.ResultsCytochrome P450 2J2 (CYP2J2) is a member of the hemoprotein superfamily of cytochromes P450 (CYPs). CYP2J2 is responsible for the endogenous metabolism of several polyunsaturated fatty acids (PUFAs) into various regioisomers of epoxides and hydroxides. Most notably, it is responsible for the metabolism of arachidonic acid (AA) into epoxyeicosatrienoic acids (EETs) and hydroxyeicosatrienoic acids (HETEs). Other PUFA substrates include the ω‐6 linoleic acid (LA), and the ω‐3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Collectively, the epoxides are potent anti‐inflammatory, vasodilatory, and cardioprotective compounds; however, the ω‐3 varieties are generally more potent and beneficial. Additionally, many of these PUFAs can be metabolized at different sites of the molecule, leading to altered efficacies in signaling. For instance, 5,6‐EET has been shown to be anti‐inflammatory and 8,9‐EET has been shown not to protect against reactive‐oxygen‐species‐ (ROS)‐mediated damage. In addition to PUFAs, CYP2J2 is responsible for the metabolism of several drugs, including some cardiotoxic drugs such as terfenadine. Studying how these various molecules orchestrate to modulate CYP2J2‐mediated cardioprotection is an unexplored pathway and may lead to a better understanding of cardiotoxicity.Herein, we have investigated how AA, DHA, EPA, and LA compete for CYP2J2 metabolism using kinetic and Soret titration binding assays. We found that DHA significantly inhibits AA metabolism and shows preferential metabolism. DHA also binds to CYP2J2 more tightly compared to the other PUFAs. Molecular dynamic simulations show that DHA forms more stable interactions with key CYP2J2 residues, which may explain the tightness of binding and greater inhibition. We have also investigated how the anticancer drug, doxorubicin (DOX), modulates CYP2J2‐mediate AA metabolism. DOX is especially cardiotoxic partly due to its production of reactive oxygen species (ROS). We found that DOX inhibits AA metabolism whilst also changing the regioselectivity to less‐cardioprotective EETs. These two events may help to explain some of the cardiotoxicity exhibited by DOX and may lead to better drug designs.ConclusionsPUFAs show similar competitive interactions for metabolism by CYP2J2. DHA, however, is the strongest inhibitor of AA metabolism due to tighter selective binding. This suggests that DHA displays preferential metabolism by CYP2J2.DOX alters the binding of AA by CYP2J2 and thereby inhibits its activity and alters the EET regioisomer ratio. These may be responsible for lowering the efficacy of CYP2J2‐mediated protection from DOX‐mediated ROS injury.Support or Funding InformationAmerican Heart Association Scientist Development grant [15SDG25760064] (AD) and in part by the National Institutes of Health R01‐GM101048, U54‐GM087519, and P41‐GM104601 (ET). All simulations have been performed using XSEDE resources (grant MCA06N060 to ET).