Class C GPCR biology – probing novel drug paradigms
Class C G protein-coupled receptors (GPCRs) include receptors for neurotransmitters (e.g. GABAB receptor), amino acids (metabotropic glutamate receptors, taste receptors), and cations (calcium-sensing receptor). We are interested in how endogenous and small molecule ligands regulate the activity of this protein family, with a particular focus on allosteric ligands that bind to sites distinct from those of endogenous ligands. Indeed, the first allosteric ligand to make it into the clinic, cinacalcet (SensiparTM), interacts with the calcium-sensing receptor. Our research falls into two main therapeutic areas: metabolic, and neuropsychiatric and neurological disorders.
Allosteric modulation and biased agonism at Class C GPCRs
Figure 1: Class C GPCRs are large cell surface proteins that form dimers and engender bias by binding endogenous and exogenous agonists and allosteric modulators. Model adapted from image in Wu et al., Science 2014.
Most Class C GPCRs are activated by more than one endogenous agonist, as well as endogenous and synthetic allosteric ligands. Different ligands binding to the same receptor can give rise to distinct physiological effects via a phenomenon called 'biased agonism'.
Biased agonism arises when different ligands stabilise distinct GPCR conformations, with each conformation triggering only a subset of the available intracellular effectors, at the exclusion of others. Given that allosteric ligands stabilise novel conformations by binding to sites distinct from those utilised by orthosteric ligands, there is an even greater likelihood that they will engender biased agonism.
Moreover, the receptor conformations stabilised by the simultaneous occupation of a single receptor with two or more ligands are likely to be different to those stabilised by either ligand alone. This raises the possibility of tailoring therapies to promote 'good' and avoid 'bad' effects mediated by the same receptor.
We are exploring how signalling, trafficking and regulation of Class C GPCRs is altered by different endogenous stimuli, synthetic small molecule ligands and naturally occurring mutations. To achieve this, we use recombinant cell lines and primary cultures. These studies seek to elucidate how distinct receptor behaviours contribute to the overall (patho)physiology of Class C GPCRs. This information will inform novel drug screening approaches. Indeed, our work seeks to lead to the development of more effective therapies for a wide range of disorders.
Structural biology of Class C GPCRs
Figure 2: Class C GPCR structural biology will aid structure-based drug discovery.
Rational drug discovery approaches require a precise understanding of the structural basis of drug-receptor interactions and drug-stabilised protein conformations. Moreover, protein structural insights can reveal novel drug binding pockets that may be selectively targeted.
Current crystal structures for Class C GPCRs have been solved with significant protein engineering, including truncations, addition of tags and thermostabilising mutations. There remains a critical need to understand how structure is related to function within the context of full length wild type receptors.
In order to realise this potential our group is:
- Developing and validating novel chemical tools to facilitate structural studies
- Engineering Class C GPCRs to enable purification and structure elucidation
- Exploring the structural basis of biased agonism and allosterism through site-directed mutagenesis
- Applying advanced computational methods to virtually identify novel chemical entities
Class C GPCR biology lab members
Ms. Sabine Albold – Research Assistant
Dr Aaron De Bono – Research Fellow (medicinal chemistry)
Dr Shane Hellyer – Research Fellow (molecular pharmacology)
Dr Andrew Keller – Research Fellow (structural biology)
Ms. Kathy Sengmany – PhD candidate
Recent past members:
Dr Elham Khajehali – PhD student 2015, Research Fellow 2016
Ms. Alisha Panwar – B.Pharm. honours student 2016
Mr. Taide Wang – B.Biomed.Sci. honours student 2016
Ms. Vyvyan Mai – B.Pharm.Sci. Honours student 2015
Mr. Aaron Townley – B.Pharm.Sci. Honours student 2015
Mr. Junaid Singh – B.Sc. Honours student 2014
Mr. Vinesh Patel – M. Pharm (UK) 2014 (final year project)
Recent relevant publications
Sengmany K, Singh J, Stewart GD, Conn PJ, Christopoulos A, Gregory KJ (2017) “Biased allosteric agonism and modulation of metabotropic glutamate receptor 5: Implications for optimizing preclinical neuroscience drug discovery” Neuropharmacology, 15:115:60-72.
Gregory KJ, Velagaleti R, Thal DM, Brady RM, Christopoulos A, Conn PJ, Lapinsky DJ (2016) “Clickable Photoaffinity Ligands for Metabotropic Glutamate Receptor 5 Based on Select Acetylenic Negative Allosteric Modulators” ACS Chem Biol., 11(7):1870-9.
Leach K, Gregory KJ, Kufareva I, Khajehali E, Cook, AE, Abagyan, Conigrave AD, Sexton PM and Christopoulos A (2016) “Towards a structural understanding of allosteric drugs at the human calcium-sensing receptor Cell Research, 26(5):574-92.
Thal DM, Sun B, Feng D, Nawaratne V, Leach K, Felder CC, Bures MG, Evans D, Weis WI, Bachhawat P, Kobilka TS, Sexton PM, Kobilka BK & Christopoulos A (2016) “Crystal structures of the M1 and M4 muscarinic acetylcholine receptors and insights into their allosteric modulation” Nature, 531:335-40.
Khajehali E, Malone DT, Glass M, Sexton PM, Christopoulos A & Leach K (2015) “Biased agonism and biased modulation at the CB1 cannabinoid receptor” Mol. Pharmacol. 88(2):368-379.
Nickols HH, Yuh JP, Gregory KJ, Morrison RD, Bates BS, Stauffer SR, Emmitte KA, Bubser M, Peng W, Nedelcovych MT, Thompson A, Lv X, Xiang Z, Daniels JS, Niswender CM, Lindsley CW, Jones CK, Conn PJ (2016) “VU0477573: Partial Negative Allosteric Modulator of the Subtype 5 Metabotropic Glutamate Receptor with In Vivo Efficacy” J Pharmacol Exp Ther., 356(1):123-36.
Rook JM, Xiang Z, Lv X, Ghoshal A, Dickerson JW, Bridges TM, Johnson KA, Foster DJ, Gregory KJ, Vinson PN, Thompson AD, Byun N, Collier RL, Bubser M, Nedelcovych MT, Gould RW, Stauffer SR, Daniels JS, Niswender CM, Lavreysen H, Mackie C, Conde-Ceide S, Alcazar J, Bartolome-Nebreda JM, Macdonald GJ, Talpos JC, Steckler T, Jones CK, Lindsley CW & Conn PJ (2015) “Biased mGlu5-positive allosteric modulators provide in vivo efficacy without potentiating mGlu5 modulation of NMDAR currents” Neuron 86(4):1029-1040.
Cook AE, Mistry SN, Gregory KJ, Furness SG, Sexton PM, Scammells PJ, Conigrave AD, Christopoulos A & Leach K (2014) “Biased allosteric modulation at the CaSR engendered by structurally diverse calcimimetics” Br. J. Pharmacol. 172(1):185-200.
Wu H, Wang C, Gregory KJ, Han GW, Cho HP, Xia Y, Niswender CM, Katrich V, Meiler J, Cherezov V, Conn PJ & Stevens RC (2014) “Structure of a class C GPCR metabotropic glutamate receptor 1 bound to an allosteric modulator” Science 344(6179)58-64.
Gregory KJ, Nguyen ED, Malosh C, Mendenhall JL, Zic JZ, Bates BS, Noetzel MJ, Squire EF, Turner EM, Rook JM, Emmitte KA, Stauffer SR, Lindsley CW, Meiler J & Conn PJ (2014) “Identification of specific ligand-receptor interactions that govern binding and cooperativity of diverse modulators to a common metabotropic glutamate receptor 5 allosteric site” ACS Chem. Neurosci. 5(4)282-295.
Yin S, Noetzel MJ, Johnson KA, Zamorano R, Jalan-Sakrikar N, Gregory KJ, Conn PJ & Niswender CM (2014) “Selective actions of novel allosteric modulators reveal functional heteromers of metabotropic glutamate receptors in the CNS” J. Neurosci. 34(1):79-94.
Avlani V, Ma W, Mun HC, Leach K, Delbridge L, Christopoulos A & Conigrave AD (2013) “Calcium-sensing receptor-dependent activation of CREB phosphorylation in HEK293 cells and human parathyroid cells” Am. J Physiol. Endocrino.l Metab. 304(10):E1097-104.
Leach K, Wen A, Cook AE, Conigrave AD, Sexton PM & Christopoulos A (2013) “Impact of clinically relevant mutations on the pharmacoregulation and signalling bias of the calcium-sensing receptor by positive and negative allosteric modulators”Endocrinology 154(3):1105-16.
Gregory KJ, Nguyen ED, Reiff SD, Squire EF, Stauffer SR, Lindsley CW, Meiler J & Conn PJ (2013) “Probing the Metabotropic Glutamate Receptor 5 (mGlu5) Positive Allosteric Modulator (PAM) Binding Pocket: Discovery of Point Mutations That Engender a “Molecular Switch” in PAM Pharmacology” Mol. Pharmacol. 83(5):991-1006.
Leach K, Wen A, Davey AE, Conigrave AD, Sexton PM & Christopuolos A (2012) “Identification of molecular phenotypes and biased signalling induced by naturally occurring mutations of the human calcium-sensing receptor”Endocrinology 153(9)4304-16.
Davey AE, Leach K, Valant C, Conigrave AD, Sexton PM & Christopoulos A (2012) “Positive and negative allosteric modulators promote biased signalling at the calcium-sensing receptor” Endocrinology 153(3):1232-41.
Gregory KJ, Sexton PM, Tobin AB & Christopoulos A (2012) “Stimulus bias provides evidence for conformational constraints in the structure of a G protein-coupled receptor” J Biol Chem 287(44):37066-77.
Gregory KJ, Noetzel MJ, Rook JM, Vinson PJ, Stauffer SR, Rodriguez AL, Emmitte KA, Zhou Y, Chun AC, Felts AS, Chauder BA, Lindsley CW, Niswender CM & Conn PJ (2012) “Investigating mGlu5 allosteric modulator cooperativity, affinity and agonism: enriching structure-function studies and structure-activity relationships” Mol Pharmacol. 82(5):860-75.
Leach K and Gregory KJ (2017) “Molecular insights into allosteric modulation of Class C G protein-coupled receptors” Pharmacol Res., 116:105-118.
Hellyer S, Leach K and Gregory KJ (2017) “Neurobiological insights and novel therapeutic opportunities for CNS disorders from mGlu receptor allosteric and biased modulation” Curr Opin Pharmacol., 32:49-55.
Lindsley CW, Emmitte KA, Hopkins CR, Bridges TM, Gregory KJ, Niswender CM, Conn PJ (2016) “Practical Strategies and Concepts in GPCR Allosteric Modulator Discovery: Recent Advances with Metabotropic Glutamate Receptors” Chem Rev., 116(11):6707-41
Sengmany K & Gregory KJ (2016) “Metabotropic glutamate receptor 5: molecular pharmacology, allosteric modulation and stimulus-bias” Br J Pharmacol 173(20):3001-17.
Leach K, Conigrave AD, Sexton PM & Christopoulos A (2015) “Towards tissue-specific pharmacology: insights from the calcium-sensing receptor as a paradigm for GPCR (patho)physiological bias” Trends Pharmacol. Sci. 36(4):215-225.
Gregory KJ & Conn PJ (2015) “Molecular Insights into Metabotropic Glutamate Receptor Allosteric Modulation” Mol Pharmacol 88(1):188-202.
Leach K, Sexton PM, Christopoulos A & Conigrave AD (2014) “Engendering biased signalling from the calcium-sensing receptor for the pharmacotherapy of diverse disorders” Br J Pharmacol. 171(5)1142-1155.
Gregory KJ, Dong EN, Meiler J & Conn PJ (2011) “Allosteric Modulation of Metabotropic Glutamate Receptors: Structural Insights and Therapeutic Potential” Neuropharmacol.60:66-81.
Chemical and Structural biology of Class C GPCRs:
Dr Ben Capuano – Medicinal Chemistry, MIPS
Dr Irina Kufareva – University of California San Diego, USA
Associate Professor David J. Lapinsky – Duquesne University, USA
Professor Jens Meiler – Vanderbilt University, USA
Professor Patrick Sexton – DDB, MIPS
Dr David Thal – DDB, MIPS
Dr Andrea Vernall - University of Otago, NZ.
Dr Denise Wootten - DDB, MIPS
Allosteric modulation and biased signalling of Class C GPCRs:
Professor Arthur Christopoulos – DDB, MIPS
Professor Arthur Conigrave – University of Sydney
Professor P. Jeffrey Conn – Vanderbilt Centre for Neuroscience Drug Discovery, USA
Dr Colleen M. Niswender – Vanderbilt Centre for Neuroscience Drug Discovery, USA
Physiological and pathophysiological roles for Class A and C GPCRs:
Dr Gursh Chana – Centre for Neural Engineering, University of Melbourne
Dr Lauren May - DDB, MIPS
Professor Stan Skafidas – Centre for Neural Engineering, University of Melbourne
ARC Future Fellowship (2017-2021) CIA: Karen Gregory “Exploring metabotropic glutamate receptor 5 bias, allostery and heteromers”
ARC Future Fellowship (2016-2020) CIA: Katie Leach “Understanding bias and allostery at the calcium sensing receptor”
ARC Discovery grant (2017-2019) CIA: Katie Leach, CIB: Karen J Gregory, CIC: Ben Capuano “Stabilising biased allosteric G protein-coupled receptor conformations”
NHMRC Project grant (2017-2019) CIA: Karen J Gregory, CIB: Lauren T May, CIC: Andrea Vernall "Investigating the impact of coincident modulation of adenosine and glutamate receptors on neuronal activity - implications for CNS drug discovery"
NHMRC Project grant (2015-2017) CIA: Karen J Gregory “Biased allosteric modulators of metabotropic glutamate receptors: novel therapeutic target for CNS disorders”
NHMRC Project grant (2015-2017) CIA: Katie Leach, CIB: Arthur Conigrave, CIC: Rebecca Mason “Engendering biased signalling at the human calcium sensing receptor (CaSR) to correct pathophysiology”
Monash University “Women in Research” grant (2016) Katie Leach
Faculty of Pharmacy & Pharmaceutical Sciences lab start-up funds (2013-2015)
NHMRC Overseas Biomedical Research Fellowship (2011 – 2015) Karen J Gregory “Enhancement of glutamate signaling as a novel approach to treat schizophrenia and cognitive disorders”
Monash Institute of Pharmaceutical Sciences seed grant (2014) Katie Leach
NHMRC project grant (2011-2014) Katie Leach “Allosteric modulation and biased signaling at the calcium sensing receptor”
NARSAD – Maltz Young Investigator (2011-2013): Karen J Gregory “Positive allosteric modulation of metabotropic glutamate receptor 5: a novel approach for the treatment of schizophrenia”
American Australian Association Merck Co. Foundation Fellow (2010) Karen J Gregory “Positive allosteric modulation of metabotropic glutamate receptor 5: a novel approach for the treatment of schizophrenia and cognitive disorders”