May/White Laboratory

New Paradigms of Adenosine Receptor Pharmacology

Project areas

Research focus

Adenosine A3 receptors (green) bound by a fluorescent antagonist (red).

Adenosine receptor stimulation represents a powerful mechanism to maintain homeostasis, resolve inflammation and promote tissue protection/repair during conditions such as inflammation and ischaemia-reperfusion injury. Unfortunately the transition of adenosine receptor ligands into the clinic has been  severely  hindered  due to high doses causing adverse effects such as bradycardia and hypotension.

New paradigms of adenosine receptor pharmacology including allosterism, dimerization and biased agonism have considerable clinical potential as they present the opportunity to develop therapeutics that promote desired, but minimize unwanted, on-target signal transduction.

The May/White laboratory aims to understand the molecular mechanisms underlying new paradigms of adenosine receptor pharmacology and investigate how these approaches can be exploited for the development of novel therapeutics. Techniques employed include fluorescent/radioligand binding, measurement  of  second  messenger formation, high-end fluorescence microscopy and ex vivo/in vivo cardiac ischaemia-reperfusion.

Adenosine Receptor Biased Agonism to Treat Ischaemic Heart Disease


In contrast to prototypical A1AR agonists, the biased agonist, VCP746, mediates cytoprotection in the absence of bradycardia.

Adenosine receptor signalling within cardiomyocytes, either during or subsequent to ischaemia-reperfusion injury, reduces infarct size and improves post-ischemic heart function. However, the transition of AR agonists into the clinic has been severely hindered due to on-target side effects like bradycardia,  atrioventricular  block  and hypotension.

Preliminary studies of the recently identified adenosine receptor biased agonist, VCP746, suggest this compound confers potent cardioprotective and anti-remodelling effects with minimal impact on heart rate or blood pressure; enabling the separation of desired effects from adverse effects. This project  will  provide  a mechanistic insight into VCP746 in acute and long-term models of ischaemia-reperfusion injury, cardiac remodelling and heart failure.

Studies outlined within this  research plan will enhance the development of adenosine receptor agonists as  potent cardioprotective and anti-remodelling therapeutics with an acceptable  side effect profile.

Adenosine Receptor-Mediated Attenuation of Organ Transplant Rejection


Classical signalling pathways stimulated by adenosine receptors.

Allograft rejection and ischemia-reperfusion injury remains a major cause of morbidity and mortality in organ transplant recipients. Adenosine accumulates under conditions of cellular stress, including ischemia-reperfusion injury and inflammation, and mediates intracellular signal transduction through  four  adenosine  receptors (ARs), A1AR, A2AAR, A2BAR and A3AR.

The A1AR and A2BAR typically confer cell protection through direct effects on the tissue, whereas A2AAR stimulation mediates potent anti-inflammatory effects. The aim of this study is to characterise the cytoprotective signal transduction mediated by prototypical and biased  AR  agonists.  Studies will be performed within model systems and relevant primary cells under both control and disease conditions. Key findings will be translated into  animal models of organ transplantation.

Investigating the Modulation of Adenosine A1 Receptor Mediated Cardioprotection by Adenosine A2 Receptors


The molecular mechanism underlying the modulation of A1AR-mediated cardioprotection by A2ARs may involve interactions across dimers or synergistic signal transduction.

Adenosine receptor (AR) activation represents the most powerful and well-studied cardioprotective mechanism. We have recently identified a novel A1AR signalling paradigm involved in cardioprotection. That is, an absolute requirement of coincident A2AR activation for cardioprotection mediated by prototypical A1AR selective agonists.

Although the molecular mechanisms underlying this phenomenon are currently unknown, they may involve synergistic interactions either between compartmentalized AR signalling partners or across A1AR/A2AR dimers. The current project involves investigating at a subcellular level, the influence of A2AR activation on the kinetics of A1AR ligand binding and signal transduction. A1AR-mediated signal transduction will be investigated in the absence  and  presence  of A2AR agonists in single isolated cardiomyocytes.

Cooperative interactions between AR orthosteric binding sites will be quantified in live cells using a number of high-end fluorescence techniques. These  studies will establish, for  the first time, the molecular basis of A2AR  modulation of A1AR-mediated cardioprotection.

Structure-function analysis of adenosine A1 receptor allosteric binding sites


A1AR homology model based on the A2AAR crystal structure. Predicted binding regions for adenosine and allosteric ligands are shown in pink and blue, respectively.

The adenosine A1 receptor (A1AR) is known to possess at least one allosteric site that can be selectively targeted by novel small molecule modulators. However, the allosteric effects of these compounds are relatively modest, highlighting the requirement of new approaches to facilitate the design  of  more  potent, selective and efficacious A1AR modulators.

One key question in this regard is the location of the allosteric binding site on the A1AR. Structural knowledge of this binding domain can be utilized to rationally design new allosteric modulators and to inform ongoing structure-activity studies.

The current project will utilize state of the art molecular biology, molecular modelling and pharmacological techniques to probe the A1AR orthosteric and allosteric binding pockets and thus delineate the structure-function relationship underlying the modulation of this drug target by small molecules. Key findings will assist in the design of better therapeutics for the  treatment of ischaemia-reperfusion and neuropathic pain.

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Key publications

Dr Lauren T. May

Research Papers

Valant C, May LT*, Aurelio L, Chuo C, White PJ, Baltos J, Sexton PM, Scammells PJ, Christopoulos A (2014) Separation of on-target efficacy from adverse effects through rational design of a bitopic adenosine receptor agonist. Proc Natl Acad Sci U.S.A. Epub ahead of print. *Co-First Author

Siddiquee K, Hampton J, McAnally D, May LT, Smith LH (2013) The apelin receptor inhibits the angiotensin II type 1 receptor via allosteric trans-inhibition. British Journal of Pharmacology 168:1104-17

Wootten D, Savage EE, Valant C, May LT, Sloop KW, Ficorilli J, Showalter AD, Willard FS, Christopoulos A, Sexton P (2012) Allosteric modulation of endogenous metabolites as an avenue for drug discovery. Mol Pharmacol 82:281-90

May LT, Bridge LJ, Stoddart LA, Briddon SJ, Hill SJ (2011) Allosteric interactions across native adenosine-A3 receptor homodimers: quantification using single-cell ligand-binding kinetics. The FASEB Journal 25:3465-76

May LT, Self TJ, Briddon SJ, Hill SJ (2010) The effect of allosteric modulators on the kinetics of agonist-G protein-coupled receptor interactions in single living cells. Mol Pharmacol 78:511-23

May LT, Briddon SJ, Hill SJ (2010) Antagonist selective modulation of adenosine –A1 and –A3 receptor pharmacology by Brilliant Black BN: Evidence for allosteric interactions. Mol Pharmacol 77:678-86

May LT, Avlani VA, Langmead CJ, Herdon HJ, Wood MJ, Sexton PM and Chistopoulos A (2007) Structure-function studies of allosteric agonism at M2 muscarinic acetylcholine receptors. Mol Pharmacol 72:463-76

Bisson WH and Cheltsov AV, Bruey-Sedano N, Lin B, Chen J, Goldberger N, May  LT, Christopoulos A, Dalton JT, Sexton PM, Zhang XK, Abagyan R. (2007) Discovery of Antiandrogen Activity of Non-steroidal Scaffolds of Marketed Drugs. Proc Natl Acad Sci U.S.A. 104:11927-32

May LT, Sexton PM and Christopoulos A (2005) Effects of urea pretreatment on the binding properties of adenosine A1 receptors. British Journal of Pharmacology 146:1119-29.

May LT, Lin Y, Sexton PM and Christopoulos A (2005) Regulation of M2 muscarinic acetylcholine receptor expression and signaling by prolonged exposure to allosteric modulators. J Pharmacol Exp Ther 312:382-90.

Review Papers

Hill SJ, May LT, Kellam B, Woolard J (2014) Allosteric interactions at adenosine A1 and A3 receptors: New insights into the role of small molecules and receptor dimerization. British Journal of Pharmacology 171:1102-1113

Hill SJ, Williams C, May  LT (2010) Insights into GPCR pharmacology from the measurement of changes in intracellular cyclic AMP; Advantages and pitfalls of differing methodologies. British Journal of Pharmacology 161:1266-75

May LT, Holliday ND, Hill, SJ (2010) The evolving Pharmacology of GPCRs. GPCR Molecular Pharmacology and Drug Targeting: Shifting Paradigms in G Protein Coupled Receptors. Chapter 2:27-60

May LT, Hill SJ (2008) ERK phosphorylation: Spatial and temporal regulation by G protein-coupled receptors. Int J Biochem Cell Biol 40:2013-7

May LT, Leach K, Sexton PM and Christopoulos A (2007) Allosteric Modulation of G Protein-Coupled Receptors. Annu Rev Pharmacol Toxicol. 47:1-51

Dr Paul J. White

Research Papers

Valant C, May LT*, Aurelio L, Chuo C, White  PJ, Baltos J, Sexton PM, Scammells PJ, Christopoulos A (2014) Separation of on-target efficacy from adverse effects through rational design of a bitopic adenosine receptor agonist. Proc Natl Acad Sci U.S.A. Epub ahead of print. *Co-First Author

Lau S, Graham B, Cao N, Boyd BJ, Pouton CW, White PJ (2012) Enhanced extravasation, stability and in vivo cardiac gene silencing via in situ siRNA-albumin conjugation. Molecular pharmaceutics 9(1):71-80

Hausler NE, Devine SM, McRobb FM, Warfe L, Pouton CW, Haynes JM, White PJ * & Scammells PJ* (2012) Synthesis and pharmacological evaluation of dual acting antioxidant A(2A) adenosine receptor agonists. Journal of Medicinal Chemistry 55(7):3521-34.

Valant C, Aurelio L, Urmaliya VB, White PJ, Scammells PJ, Sexton PM, et al. (2010) Delineating the mode of action of adenosine A1 receptor allosteric modulators. Molecular pharmacology 78(3):444-55

Urmaliya VB, Pouton CW, Ledent C, Short JL, White  PJ (2010) Cooperative cardioprotection through adenosine A1 and A2A receptor agonism in ischemia-reperfused isolated mouse heart. Journal of cardiovascular pharmacology 56(4):379-88 Urmaliya VB, Pouton CW, Devine SM, Haynes JM, Warfe L, Scammells PJ, White PJ. (2010) A  novel  highly  selective adenosine A1 receptor agonist VCP28 reduces ischemia injury in a cardiac cell line and ischemia-reperfusion injury in isolated rat hearts at concentrations that do not affect heart rate. Journal of cardiovascular pharmacology 56(3):282-92

Urmaliya VB, Church JE, Coupar IM, Rose'Meyer RB, Pouton CW, White PJ. (2009) Cardioprotection induced by adenosine A1 receptor agonists in a cardiac cell ischemia model involves cooperative activation of adenosine A2A and A2B receptors by endogenous adenosine. Journal of cardiovascular pharmacology 53(5):424-33

White PJ, Anastasopoulos F, Church JE, Kuo CY, Boyd BJ, Hickey PL, et al. (2008) Generic construction of single component particles that elicit humoural and cellular immune responses without the need for adjuvants. Vaccine 26(52):6824-31

Nguyen TT, Cao N, Short JL, White  PJ. (2006) Intravenous insulin-like growth factor-I receptor antisense treatment reduces angiotensin receptor expression and function in spontaneously hypertensive rats. The Journal of pharmacology and experimental therapeutics 318(3):1171-7

Wraight CJ, White PJ, McKean SC, Fogarty RD, Venables DJ, Liepe IJ, et al. (2000) Reversal of epidermal hyperproliferation in psoriasis by insulin-like growth factor I receptor antisense oligonucleotides. Nat Biotechnol. 18(5):521-6

Review Papers

White PJ, Anastasopoulos F, Pouton CW, Boyd BJ. (2009) Overcoming biological barriers to in vivo efficacy of antisense oligonucleotides. Expert reviews in molecular medicine 11:e10

White PJ. Barriers to successful delivery of short interfering RNA after systemic administration. (2008) Clinical and experimental pharmacology & physiology 35(11):1371-6

White PJ, Atley LM, Wraight CJ. (2004) Antisense oligonucleotide treatments for psoriasis. Expert opinion on biological therapy 4(1):75-81

Wraight CJ, White PJ. (2001) Antisense oligonucleotides in cutaneous therapy. Pharmacol Ther. 90(1):89-104

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Collaborations

Adenosine Receptor Biased Agonism to Treat Ischaemic Heart Disease (LTM & PJW)

  • Prof  Peter Scammells, Medicinal Chemistry and Drug Action, MIPS, Monash University
  • Prof  Arthur Christopoulos, Drug Discovery Biology, MIPS, Monash University
  • Prof  Patrick Sexton, Drug Discovery Biology, MIPS, Monash University
  • Prof Henry Krum, Department of Epidemiology & Preventive Medicine, Monash University
  • Dr Bing Wang, Department of Epidemiology & Preventive Medicine, Monash University
  • Dr Andrew Kompa, Department of Epidemiology & Preventive Medicine, Monash University

Structure-function analysis of allosteric binding sites on adenosine A1 receptors (LTM)

  • Prof  Arthur Christopoulos, Drug Discovery Biology, MIPS, Monash University
  • Dr Laura Lopez, Drug Discovery Biology, MIPS, Monash University

VCP746, a novel adenosinergic therapeutic, promotes beta-cell regeneration (LTM)

  • Dr Karen Dwyer, St. Vincent's Hospital, Immunology Research Centre

Novel GPCR mechanisms to treat neural hyper-excitation in chronic pain (LTM)

  • Professor Macdonald Christie, Pharmacology, School of Medical Sciences, The University of Sydney
  • Prof  Arthur Christopoulos, Drug Discovery Biology, MIPS, Monash University

GPCR regulation, trafficking and compartmentalisation in breast cancer metastasis (LTM)

Formyl peptide receptor signal transduction (LTM)

  • A/Prof Rebecca Ritchie, Heart Failure Pharmacology, Baker IDI Heart & Diabetes Institute
  • Chengxue Helena Qin, Heart Failure Pharmacology, Baker IDI Heart & Diabetes Institute
  • Prof  Arthur Christopoulos, Drug Discovery Biology, MIPS, Monash University
  • Prof  Patrick Sexton, Drug Discovery Biology, MIPS, Monash University
  • Adenosine Receptor-Mediated Attenuation of Organ Transplant Rejection (LTM)
  • Professor Robert Jones, Liver Transplant Unit Director, Austin Hospital

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Lab members

Ms Anh T. Nguyen
PhD Candidate

Ms Jo-Anne Baltos
PhD Candidate

Ms Elizabeth McBrearty
PhD Candidate

Mr Chung Chuo
PhD Candidate

Dr Christina Tan
Post-Doctoral Researcher

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Funding

Dr Lauren T. May

  • ARC DERCA Fellowship (2013 – 2015) "Allosteric Fingerprinting of G Protein-Coupled Receptor Monomers and Oligomers"
  • Co-PI, JDRF Project Grant (2013 – 2014) "VCP746, a novel adenosinergic therapeutic, promotes beta-cell regeneration"

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