Defining the functional roles of the enigmatic G protein-coupled receptor GPR35
Lead Research Organisation:
University of Glasgow
Department Name: College of Medical, Veterinary, Life Sci
Abstract
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Technical Summary
Despite suggestions that it may be a receptor for a metabolite of tryptophan (kynurenic acid), a lipid (a form of lysophosphatidic acid) or a chemokine (CXCL17) GPR35 remains an 'orphan' GPCR. However, expression patterns, genome wide association studies and activation by a previously used anti-asthma medicine, suggest important roles for GPR35 in inflammatory conditions of the gut and airways/lung. Here we aim to investigate the mechanisms of GPR35 signal transduction and regulation, and to employ pharmacological tool compounds in combination with genetically modified mice to dissect the modes of action and physiological role and therapeutic potential of GPR35. This will involve using approaches, including G protein biosensors and CRISPR/cas knock-out of G proteins and arrestins, to investigate the mechanistic basis of GPR35 signalling. In particular we will evaluate the prospect that currently available GPR35 ligands may show signalling bias by preferentially promoting coupling through G proteins or arrestins. Interestingly, mouse and human GPR35 show large differences in basic pharmacology, including that a pair of GPR35 'antagonists' have affinity only for the human receptor. We will exploit this difference to explore the in vivo functions of GPR35 by generating mutant mouse lines expressing human GPR35. In this way the action of human specific GPR35 chemical tools can be used to probe the function and potential clinical relevance of GPR35. We will also generate knock-in mice expressing a form of GPR35 which is G protein 'biased' and cannot be phosphorylated or engage beta-arrestins to define the in vivo modes of signal transduction of GPR35. Hence, by combining in vitro analysis using the 'gene edited' cells and sensors with ex vivo and in vivo analysis of the transgenic 'knock-in' lines, with particularly focus on lung and colon inflammatory disease models, we will provide unique insights into the function of GPR35 and indicate its therapeutic potential.
Planned Impact
Who will benefit from this research?
The most immediate beneficiaries from the research will be academic researchers with interests both specifically related to GPR35 and, more generally, as described in the 'Case for Support' in 'Western lifestyle' inflammatory diseases. This is an area that is attracting enormous interest, with clear links between diet and health that extend to 'healthy aging' and possible intervention in disease or lifestyle via 'functional foods'. Although only recently becoming widely appreciated, many metabolites derived from food sources in the diet are now known to function as key homeostatic beacons and do so, at least in part by activating group of GPCRs expressed by cells and tissues that sense metabolic status. However, beyond these specific health-related aspects, there is vast interest in novel approaches to better understand GPCR function in general, and both the novel sensors we describe and the HEK293 cell lines lacking various G protein or arrestins and the results generated using them will be of great interest to virtually all of the vast number of researchers who work on GPCR-induced signalling. This includes stakeholders across the pharma/biotech sector as well as academic teams. Although the only current and ongoing clinical trials targeting GPR35 that we are aware of (from Patara Pharma (http://patarapharma.com/)) employ an undefined GPR35 agonist coded as 'PA101B' which is described as 'a GPR35 agonist immune modulator with mast cell stabilizing properties' and is being assessed to treat chronic cough and indolent systemic mastocytosis, there is also considerable interest in the mode of action of the anti-asthma medicine sodium cromoglycate, which displays modest potency as an agonist at GPR35. As many companies have 'respiratory disease' programmes, novel insights emerging from these studies are likely to attract attention also in this sphere. A number of companies (see e.g. Mackenzie et al., (2014) Mol. Pharmacol. 85, 91-104) have assisted us in the search for high potency agonist ligands of GPR35 and it is likely they would remain extremely interested in the outcomes and progress of these studies.
How will they benefit from this research?
As well as greater insight into specific roles of 'biased' signalling the research community will benefit from access to the many novel tools and reagents we have and will generate within this project. We will provide the transgenic mouse lines to appropriate interested partners as described within the 'Data management plan'. In a similar manner, if agreed to within MTAs developed by our Japanese collaborators at Tohoku University, we will also provide the gene edited 'knock out' cell lines as described, once key output publications have been achieved. The project has great potential in terms of staff training in that the PDRAs will benefit from opportunities to perform cutting edge research in a broad swathe of areas relevant to modern pharmacological and physiological studies and to enhance team working via the need to integrate work from two sites. They will also benefit greatly from the opportunities provided to travel and to work with our key collaborators in Germany to access to high end equipment and technologies (see Letters of Support from Evi Kostenis and Carsten Hoffmann). This training will ensure the greatest range of subsequent career opportunities.
The most immediate beneficiaries from the research will be academic researchers with interests both specifically related to GPR35 and, more generally, as described in the 'Case for Support' in 'Western lifestyle' inflammatory diseases. This is an area that is attracting enormous interest, with clear links between diet and health that extend to 'healthy aging' and possible intervention in disease or lifestyle via 'functional foods'. Although only recently becoming widely appreciated, many metabolites derived from food sources in the diet are now known to function as key homeostatic beacons and do so, at least in part by activating group of GPCRs expressed by cells and tissues that sense metabolic status. However, beyond these specific health-related aspects, there is vast interest in novel approaches to better understand GPCR function in general, and both the novel sensors we describe and the HEK293 cell lines lacking various G protein or arrestins and the results generated using them will be of great interest to virtually all of the vast number of researchers who work on GPCR-induced signalling. This includes stakeholders across the pharma/biotech sector as well as academic teams. Although the only current and ongoing clinical trials targeting GPR35 that we are aware of (from Patara Pharma (http://patarapharma.com/)) employ an undefined GPR35 agonist coded as 'PA101B' which is described as 'a GPR35 agonist immune modulator with mast cell stabilizing properties' and is being assessed to treat chronic cough and indolent systemic mastocytosis, there is also considerable interest in the mode of action of the anti-asthma medicine sodium cromoglycate, which displays modest potency as an agonist at GPR35. As many companies have 'respiratory disease' programmes, novel insights emerging from these studies are likely to attract attention also in this sphere. A number of companies (see e.g. Mackenzie et al., (2014) Mol. Pharmacol. 85, 91-104) have assisted us in the search for high potency agonist ligands of GPR35 and it is likely they would remain extremely interested in the outcomes and progress of these studies.
How will they benefit from this research?
As well as greater insight into specific roles of 'biased' signalling the research community will benefit from access to the many novel tools and reagents we have and will generate within this project. We will provide the transgenic mouse lines to appropriate interested partners as described within the 'Data management plan'. In a similar manner, if agreed to within MTAs developed by our Japanese collaborators at Tohoku University, we will also provide the gene edited 'knock out' cell lines as described, once key output publications have been achieved. The project has great potential in terms of staff training in that the PDRAs will benefit from opportunities to perform cutting edge research in a broad swathe of areas relevant to modern pharmacological and physiological studies and to enhance team working via the need to integrate work from two sites. They will also benefit greatly from the opportunities provided to travel and to work with our key collaborators in Germany to access to high end equipment and technologies (see Letters of Support from Evi Kostenis and Carsten Hoffmann). This training will ensure the greatest range of subsequent career opportunities.
People |
ORCID iD |
Andrew Tobin (Principal Investigator) |
Publications
Bradley SJ
(2018)
The use of chemogenetic approaches to study the physiological roles of muscarinic acetylcholine receptors in the central nervous system.
in Neuropharmacology
Divorty N
(2022)
Agonist-induced phosphorylation of orthologues of the orphan receptor GPR35 functions as an activation sensor.
in The Journal of biological chemistry
Ganguly A
(2023)
G protein-receptor kinases 5/6 are the key regulators of G protein-coupled receptor 35-arrestin interactions
in Journal of Biological Chemistry
Lin LC
(2021)
G Protein-Coupled Receptor GPR35 Suppresses Lipid Accumulation in Hepatocytes.
in ACS pharmacology & translational science
Mackenzie AE
(2019)
Receptor selectivity between the G proteins Ga12 and Ga13 is defined by a single leucine-to-isoleucine variation.
in FASEB journal : official publication of the Federation of American Societies for Experimental Biology
Marti-Solano M
(2020)
Combinatorial expression of GPCR isoforms affects signalling and drug responses.
in Nature
Milligan G
(2017)
FFA4/GPR120: Pharmacology and Therapeutic Opportunities.
in Trends in pharmacological sciences
Quon T
(2020)
Therapeutic Opportunities and Challenges in Targeting the Orphan G Protein-Coupled Receptor GPR35.
in ACS pharmacology & translational science
Description | We have now developed transgenic mice expressing humanised forms of this receptor and are planning to use these to determine the physiological role of GPR35. We have also determined that the species difference between GPR35 mouse and human orthologues is contained in a single amino acid in the ligand binding pocket. We have also established that this receptor is able to control gut function via two mechanisms the first is to maintain the barrier between the inside of the gut lumen and the body and secondly to control the immune response of the gut. |
Exploitation Route | Others are using our findings to further design experiments looking into the role of GPR35 |
Sectors | Pharmaceuticals and Medical Biotechnology |
Description | GlaxoSmithkline GPR35 collaboration |
Organisation | GlaxoSmithKline (GSK) |
Country | Global |
Sector | Private |
PI Contribution | Collaboration to investigate the therapeutic value of GPR35 |
Collaborator Contribution | Collaboration to investigate the therapeutic value of GPR35 |
Impact | No outcomes as yet |
Start Year | 2021 |
Description | Cell block Science - Low moss Bishop Briggs, Glasgow. |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Workshop for prisoners |
Year(s) Of Engagement Activity | 2018 |
Description | Cell block Science - Shotts Prison, Glasgow. |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Talk to prisoners |
Year(s) Of Engagement Activity | 2018 |
Description | Presentation to subcommittee on Life Sciences, Scottish Parliament on the impact of Brexit |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Policymakers/politicians |
Results and Impact | Presented to the subcommittee on Life Sciences |
Year(s) Of Engagement Activity | 2019 |
Description | • Pint of Science - Raven pub, Glasgow. June 2018 |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | 50 members of the general public at this outreach event |
Year(s) Of Engagement Activity | 2018 |