1
|
Singh K, Nawabjan SA, Zhang L, El-Nezami H, Annapureddy RR, Chow BKC. Discovery of small-molecule modulators of the secretin receptor: Purmorphamine as novel anti-hypertensive agent. Eur J Med Chem 2022; 242:114642. [DOI: 10.1016/j.ejmech.2022.114642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/17/2022] [Accepted: 07/27/2022] [Indexed: 11/04/2022]
|
2
|
Discovery of small molecule positive allosteric modulators of the secretin receptor. Biochem Pharmacol 2021; 185:114451. [PMID: 33545115 DOI: 10.1016/j.bcp.2021.114451] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/25/2021] [Accepted: 01/25/2021] [Indexed: 12/12/2022]
Abstract
The secretin receptor (SCTR) is a prototypic Class B1 G protein-coupled receptor (GPCR) that represents a key target for the development of therapeutics for the treatment of cardiovascular, gastrointestinal, and metabolic disorders. However, no non-peptidic molecules targeting this receptor have yet been disclosed. Using a high-throughput screening campaign directed at SCTR to identify small molecule modulators, we have identified three structurally related scaffolds positively modulating SCTRs. Here we outline a comprehensive study comprising a structure-activity series based on commercially available analogs of the three hit scaffold sets A (2-sulfonyl pyrimidines), B (2-mercapto pyrimidines) and C (2-amino pyrimidines), which revealed determinants of activity, cooperativity and specificity. Structural optimization of original hits resulted in analog B2, which substantially enhances signaling of truncated secretin peptides and prolongs residence time of labeled secretin up to 13-fold in a dose-dependent manner. Furthermore, we found that investigated compounds display structural similarity to positive allosteric modulators (PAMs) active at the glucagon-like peptide-1 receptor (GLP-1R), and we were able to confirm cross-recognition of that receptor by a subset of analogs. Studies using SCTR and GLP-1R mutants revealed that scaffold A, but not B and C, likely acts via two distinct mechanisms, one of which constitutes covalent modification of Cys-347GLP-1R known from GLP-1R-selective modulators. The scaffolds identified in this study might not only serve as novel pharmacologic tools to decipher SCTR- or GLP-1R-specific signaling pathways, but also as structural leads to elucidate allosteric binding sites facilitating the future development of orally available therapeutic approaches targeting these receptors.
Collapse
|
3
|
Dengler DG, Sun Q, Holleran J, Pollari S, Beutel J, Brown BT, Shinoki Iwaya A, Ardecky R, Harikumar KG, Miller LJ, Sergienko EA. Development of a Testing Funnel for Identification of Small-Molecule Modulators Targeting Secretin Receptors. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2021; 26:1-16. [PMID: 32749201 PMCID: PMC8278649 DOI: 10.1177/2472555220945284] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The secretin receptor (SCTR), a prototypical class B G protein-coupled receptor (GPCR), exerts its effects mainly by activating Gαs proteins upon binding of its endogenous peptide ligand secretin. SCTRs can be found in a variety of tissues and organs across species, including the pancreas, stomach, liver, heart, lung, colon, kidney, and brain. Beyond that, modulation of SCTR-mediated signaling has therapeutic potential for the treatment of multiple diseases, such as heart failure, obesity, and diabetes. However, no ligands other than secretin and its peptide analogs have been described to regulate SCTRs, probably due to inherent challenges in family B GPCR drug discovery. Here we report creation of a testing funnel that allowed targeted detection of SCTR small-molecule activators. Pursuing the strategy to identify positive allosteric modulators (PAMs), we established a unique primary screening assay employing a mixture of three orthosteric stimulators that was compared in a screening campaign testing 12,000 small-molecule compounds. Beyond that, we developed a comprehensive set of secondary assays, such as a radiolabel-free target engagement assay and a NanoBiT (NanoLuc Binary Technology)-based approach to detect β-arrestin-2 recruitment, all feasible in a high-throughput environment as well as capable of profiling ligands and hits regarding their effect on binding and receptor function. This combination of methods enabled the discovery of five promising scaffolds, four of which have been validated and further characterized with respect to their allosteric activities. We propose that our results may serve as starting points for developing the first in vivo active small molecules targeting SCTRs.
Collapse
Affiliation(s)
- Daniela G. Dengler
- Conrad Prebys Center for Chemical Genomics, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Qing Sun
- Conrad Prebys Center for Chemical Genomics, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - John Holleran
- Conrad Prebys Center for Chemical Genomics, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Sirkku Pollari
- Conrad Prebys Center for Chemical Genomics, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Jannis Beutel
- Department of Chemistry and Pharmacy, Chemikum, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Brock T. Brown
- Conrad Prebys Center for Chemical Genomics, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Aki Shinoki Iwaya
- Conrad Prebys Center for Chemical Genomics, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Robert Ardecky
- Conrad Prebys Center for Chemical Genomics, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Kaleeckal G. Harikumar
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona, USA
| | - Laurence J. Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona, USA
| | - Eduard A. Sergienko
- Conrad Prebys Center for Chemical Genomics, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| |
Collapse
|
4
|
Identification of a conformational heparin-recognition motif on the peptide hormone secretin: key role for cell surface binding. Biochem J 2017; 474:2249-2260. [PMID: 28536157 DOI: 10.1042/bcj20170035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/30/2017] [Accepted: 05/23/2017] [Indexed: 11/17/2022]
Abstract
Secretin is a peptide hormone that exerts pleiotropic physiological functions by specifically binding to its cognate membrane-bound receptor. The membrane catalysis model of peptide-receptor interactions states that soluble peptidic ligands initially interact with the plasma membrane. This interaction increases the local concentration and structures the peptide, enhancing the rate of receptor binding. However, this model does not consider the dense network of glycosaminoglycans (GAGs) at the surface of eukaryotic cells. These sulfated polysaccharide chains are known to sequester numerous proteic signaling molecules. In the present study, we evaluated the interaction between the peptide hormone secretin and sulfated GAGs and its contribution to cell surface binding. Using GAG-deficient cells and competition experiments with soluble GAGs, we observed by confocal microscopy and flow cytometry that GAGs mediate the sequestration of secretin at the cell surface. Isothermal titration calorimetry and surface plasmon resonance revealed that secretin binds to heparin with dissociation constants ranging between 0.9 and 4 μM. By designing secretin derivatives with a restricted conformational ensemble, we observed that this interaction is mediated by the presence of a specific conformational GAG-recognition motif that decorates the surface of the peptide upon helical folding. The present study identifies secretin as a novel GAG-binding polypeptide and opens new research direction on the functional role of GAGs in the biology of secretin.
Collapse
|
5
|
Singh K, Senthil V, Arokiaraj AWR, Leprince J, Lefranc B, Vaudry D, Allam AA, Ajarem J, Chow BKC. Correction: Structure-Activity Relationship Studies of N- and C-Terminally Modified Secretin Analogs for the Human Secretin Receptor. PLoS One 2016; 11:e0165770. [PMID: 27783654 PMCID: PMC5081163 DOI: 10.1371/journal.pone.0165770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
|
6
|
Singh K, Zaw AM, Sekar R, Palak A, Allam AA, Ajarem J, Chow BKC. Glycyrrhizic Acid Reduces Heart Rate and Blood Pressure by a Dual Mechanism. Molecules 2016; 21:molecules21101291. [PMID: 27689971 PMCID: PMC6274536 DOI: 10.3390/molecules21101291] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 09/14/2016] [Accepted: 09/22/2016] [Indexed: 01/07/2023] Open
Abstract
Beta adrenergic receptors are crucial for their role in rhythmic contraction of heart along with their role in the pathological conditions such as tachycardia and high risk of heart failure. Studies report that the levels of beta-1 adrenergic receptor tend to decrease by 50%, whereas, the levels of beta-2 adrenergic receptor remains constant during the risk of heart failure. Beta blockers—the antagonistic molecules for beta-adrenergic receptors, function by slowing the heart rate, which thereby allows the left ventricle to fill completely during tachycardia incidents and hence helps in blood pumping capacity of heart and reducing the risk of heart failure. In the present study, we investigate the potential of glycyrrhizic acid (GA) as a possible principal drug molecule for cardiac arrhythmias owing to its ability to induce reduction in the heart rate and blood pressure. We use in vitro and in silico approach to study GA′s effect on beta adrenergic receptor along with an in vivo study to examine its effect on heart rate and blood pressure. Additionally, we explore GA′s proficiency in eliciting an increase in the plasma levels of vasoactive intestinal peptide, which by dilating the blood vessel consequently, can be a crucial aid during the occurrence of a potential heart attack. Therefore, we propose GA as a potential principal drug molecule via its potential in modulating heart rate and blood pressure.
Collapse
Affiliation(s)
- Kailash Singh
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
| | - Aung Moe Zaw
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
| | - Revathi Sekar
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
| | - Ahuja Palak
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
| | - Ahmed A Allam
- Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
- Department of Zoology, Faculty of Science, Beni-Suef University, Beni-Suef 62511, Egypt.
| | - Jamaan Ajarem
- Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
| | - Billy K C Chow
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
| |
Collapse
|
7
|
Sekar R, Singh K, Arokiaraj AWR, Chow BKC. Pharmacological Actions of Glucagon-Like Peptide-1, Gastric Inhibitory Polypeptide, and Glucagon. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 326:279-341. [PMID: 27572131 DOI: 10.1016/bs.ircmb.2016.05.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Glucagon family of peptide hormones is a group of structurally related brain-gut peptides that exert their pleiotropic actions through interactions with unique members of class B1 G protein-coupled receptors (GPCRs). They are key regulators of hormonal homeostasis and are important drug targets for metabolic disorders such as type-2 diabetes mellitus (T2DM), obesity, and dysregulations of the nervous systems such as migraine, anxiety, depression, neurodegeneration, psychiatric disorders, and cardiovascular diseases. The current review aims to provide a detailed overview of the current understanding of the pharmacological actions and therapeutic advances of three members within this family including glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP), and glucagon.
Collapse
Affiliation(s)
- R Sekar
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - K Singh
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - A W R Arokiaraj
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - B K C Chow
- School of Biological Sciences, University of Hong Kong, Hong Kong, China.
| |
Collapse
|