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Allan Rettie

medicinal chemistry chair allan rettie
Professor, Medicinal Chemistry
PH: 206 543 2224
rettie@uw.edu

Education
PhD in Pharmaceutical Sciences, University of Newcastle-upon-Tyne, England; BSc, Heriot-Watt University, Scotland;
Postdoctoral Fellow, UW

Research Areas

  • Biochemistry and pharmacogenetics of the human CYP2 and CYP4 families of P450s
  • Sources of inter-individual variability in warfarin dosing

Biography

Dr. Rettie obtained a PhD in Pharmaceutical Sciences in 1983 from the University of Newcastle-upon-Tyne, England, before moving to Seattle to post-doc with Drs. Mont Juchau and Dr. Bill Trager at the UW in the areas of extrahepatic drug metabolism and metabolic drug-drug interactions, respectively. He joined the faculty of the UW School of Pharmacy in 1987 and became Departmental Chair in 2000.

Dr. Rettie's research interests have focused mainly on the human P450 enzymes and attempts to understand mechanisms of catalysis, substrate specificity, pharmacogenetic variability and adverse drug reactions related to these monooxygenases. He has published over 150 peer-reviewed papers and held research grants from the National Institutes of Health (NIH) in these topic areas for 24 years. Dr. Rettie has served on the editorial boards of Drug Metabolism and Disposition, Drug Metabolism Reviews, Journal of Pharmacology and Therapeutics, Current Drug Metabolism, and Chemico-Biological Interactions, as well as numerous NIH grant review panels.

Dr. Rettie currently chairs both the IUPHAR (International Union of Basic and Applied Pharmacology) Section of Drug Metabolism and Transport and the Scientific Affairs Committee of ISSX. In 2005, he received the North American Scientific Achievement Award from the International Society for the Study of Xenobiotics (ISSX) for his work on elucidating metabolic and pharmacogenetic mechanisms of adverse reactions to the anticoagulant drug, warfarin.


Research Overview

Metabolism by the cytochrome P450s is the principal means whereby lipid-soluble drugs and compounds foreign to the body are converted to water-soluble derivatives that can be readily excreted. This is a beneficial effect of the enzyme system. However, it is also well recognized that P450-mediated bioactivation of drugs and other xenobiotics is an important mechanism of chemical toxicity (Baillie and Rettie, 2011). Moreover, unexpected interruptions in P450 activity, due to genetic variation (Danese et al., 2012) or administration of agents that inhibit P450 activity (McDonald et al., 2012), can cause serious adverse drug reactions and contribute to disease states.

Much of the research in our laboratory focuses on the biochemistry and pharmacogenetics of the vitamin K cycle with an emphasis on how P450 enzymes interact with components of the cycle to maintain homeostasis. Human CYP2C9, for example, is the primary catalyst of (S)-warfarin metabolism. This vitamin K antagoinst is an anticoagulant drug that is very difficult to dose correctly, and there are many drug-drug and drug-gene interactions associated with its use (Rettie and Tai, 2006). An important goal for the laboratory is to define sources of inter-individual variability in warfarin dosing which can span a 100-fold range (Cooper et al., 2008). We have shown that common genetic polymorphisms in CYP2C9 decrease warfarin dose requirements by reducing the metabolic clearance of (S)-warfarin, while common polymorphisms in the warfarin target enzyme, VKORC1, affect warfarin dose by changing hepatic concentrations of this critical recycling enzyme (Rieder et al., 2005). We found recently that CYP4F2 is a vitamin K1 oxidase and common variation in this gene affects warfarin dose likely by modulating hepatic vitamin K concentrations (McDonald et al., 2009). We are currently elucidating novel metabolic pathways of vitamin K2 and the role of CYP4F2 and CYP4F11 variants in metabolizing the different forms of vitamin K. An exciting new metabolic pathway under investigation is the conversion of vitamin K1 to menaquinone-4 catalzyed, apparently, by UBIAD1, a new ancillary enzyme to the vitamin K cycle.

Other research in the laboratory is concerned with CYP4 enzymes that are potential drug targets (Edson et al., 2013), and efforts are under way to synthesize chemical inhibitors of specific CYP4-family members to better dissect their physiological roles. CYP4B1 metabolizes a host of pro-toxins, including furans, aromatic amines, and certain fatty acids to reactive intermediates that can damage the cell. In this regard, CYP4B1 is a curious member of the CYP4 family because generally these enzymes have a restricted substrate specificity that does not extend much beyond endogenous fatty acids, such as arachidonate. To evaluate the role of CYP4B1 in chemical toxicity, we have also recently developed a knockout mouse model (Parkinson et al, 2013). Finally, we are studying CYP4V2 - a novel 'orphan P450' whose substrate specificity is unknown. To date we have reported on the fatty acid substrate specificity of CYP4V2 (Nakano et al., 2009) and the enzyme's distribution in the eye (Nakano et al., 2012). Intriguingly, polymorphisms in CYP4V2 are found in patients suffering from the eye disease Bietti's Crystalline Dystrophy (BCD). We are attempting to 'de-orphanize' CYP4V2 and, in the process, discover which homeostatic mechanisms have been disrupted in BCD patients (Kelly et al., 2011).

In this work we use protein engineering coupled with conventional protein biochemistry methods for the expression and isolation of proteins and mutants of interest from heterologous hosts such as E.coli and insect cells (Mosher et al., 2008; Roberts et al., 2010). We also make extensive use of mass spectrometry (MS) for analyte quantification, including evaluation of structural changes in mutant proteins and lipidomic analysis to probe changes in endogenous metabolism due to CYP4V2 polymorphisms. We are also developing CYP4 knockout mouse models to study mechanisms of CYP4V2 and CYP4B1 toxicity in vivo. Synthetic chemistry comes into play in the preparation of new substrates, inhibitors and metabolites for P450s of interest. Our long-term goals are to understand how structure and function are related for these important P450 enzymes.


References

  • Edson KZ and Rettie AE. "CYP4 Enzymes as Potential Drug Targets: Focus on Enzyme Multiplicity, Inducers and Inhibitors, and Therapeutic Modulation of 20-Hydroxyeicosatetraenoic Acid (20-HETE) Synthase and Fatty Acid ω-Hydroxylase Activities." Curr Top Med Chem. 13:1429-40 (2013).
  • Parkinson OT, Liggett HD, Rettie AE and Kelly ED. "Generation and Characterization of a CYP4B1 Null Mouse and the Role of CYP4B1 in the Activation and Toxicity of Ipomeanol." Toxicol Sci. 134:243-50 (2013).
  • Danese E, Montagnana M, Johnson JA, Rettie AE, Zambon CF, et al. "Impact of the CYP4F2 p.V433M polymorphism on coumarin dose requirement: systematic review and meta-analysis." Clin Pharmacol Ther. 92(6):746-56 (Dec 2012).
  • Nakano M, Kelly EJ, Wiek C, Hanenberg H and Rettie AE. "CYP4V2: Ocular Localization, Oxidation of w-3 Polyunsaturated Fatty Acids and Functional Deficit of the H331P Variant in Relation to Bietti's Crystalline Dystrophy." Mol Pharmacol. 82:679-86 (2012).
  • MacDonald MG, Au N, Wittkowsky AK, and Rettie AE.  "Warfarin-Amiodarone Drug-Drug Interactions: Determination of [I]u/Ki,u for Amiodarone and its Plasma Metabolites Suggests a Major Role for a Minor Metabolite."  Clin Pharmacol Ther. 91(4):709-17 (Apr 2012).
  • Kelly EJ, Nakano M, Rohatgi P, Yarov-Yarovoy, and Rettie AE.  "Finding Homes for Orphan Cytochrome P450s: CYP4V2 and CYP4F22 in Disease States."  Mol Intervent. 11:124-132 (2011).
  • Baillie TA, Rettie AE.  "Role of Biotransformation in Drug-Induced Toxicity: Influence of Intra- and Inter-Species Differences in Drug Metabolism."  Drug Metab Pharmacokinet., 26:15-29 (2011).
  • Roberts AG, Cheesman MJ, Primak A, Bowman MK, Atkins WM, Rettie AE.  "Intramolecular Heme Ligation of the Cytochrome P450 2C9 R108H Mutant Demonstrates Pronounced Conformational Flexibility of the B-C Loop Region: Implications for Substrate Binding." Biochemistry 49:8700-8 (2010).
  • Nakano M, Kelly EJ and Rettie AE.  "Expression and characterization of CYP4V2 as a fatty acid omega-hydroxylase."  Drug Metab Dispos. 37:2119-22 (2009).
  • McDonald MG, Rieder MJ, Nakano M, Hsia CK and Rettie AE.  "CYP4F2 is a vitamin K1 oxidase: An explanation for altered warfarin dose in carriers of the V433M variant."  Mol Pharmacol. 75:1337-46 (2009).
  • Mosher CM, Hummel MA, Tracy TS and Rettie AE.  "Functional analysis of phenylalanine residues in the active site of CYP2C9."  Biochemistry 47:11725-34 (2008).
  • Cooper GM, Johnson JA, Langaee TY, Feng H, Stanaway IB, Schwartz U Ritchie MD, Stein M, Roden DM, Smith JD, Veenstra DL, Rettie AE, and Rieder MJ.  "A Whole-Genome Scan for Common Genetic Variants with a Large Influence on Warfarin Maintenance Dose."  Blood 112:1022-1027 (2008).
  • Rettie AE and Tai G. "Warfarin Pharmacogenomics: Closing in on Personalized Medicine." Mol Intervent. 6:223-227 (2006).
  • Rieder MJ, Reiner AP, Gage B, Nickerson DA, Eby M, McLeod H, Thummel KE, Blough DK, Veenstra DL, and Rettie AE. "Effect of VKORC1 Haplotypes on Transcriptional Regulation and Warfarin Dose." New Engl J Med. 353:2285-2293 (2005).


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