Publications by authors named "Sheng Y Ang"

6 Publications

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GPR55 regulates the responsiveness to, but does not dimerise with, α-adrenoceptors.

Biochem Pharmacol 2021 Jun 1;188:114560. Epub 2021 May 1.

Cardiometabolic Health Research, School of Pharmacy and Life Sciences, Robert Gordon University, Sir Ian Wood Building, Aberdeen AB10 7GJ, UK.

Emerging evidence suggests that G protein coupled receptor 55 (GPR55) may influence adrenoceptor function/activity in the cardiovascular system. Whether this reflects direct interaction (dimerization) between receptors or signalling crosstalk has not been investigated. This study explored the interaction between GPR55 and the alpha 1A-adrenoceptor (α-AR) in the cardiovascular system and the potential to influence function/signalling activities. GPR55 and α-AR mediated changes in both cardiac and vascular function was assessed in male wild-type (WT) and GPR55 homozygous knockout (GPR55) mice by pressure volume loop analysis and isolated vessel myography, respectively. Dimerization of GPR55 with the α-AR was examined in transfected Chinese hamster ovary-K1 (CHO-K1) cells via Bioluminescence Resonance Energy Transfer (BRET). GPR55 and α-AR mediated signalling (extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation) was investigated in neonatal rat ventricular cardiomyocytes using AlphaScreen proximity assays. GPR55 mice exhibited both enhanced pressor and inotropic responses to A61603 (α-AR agonist), while in isolated vessels, A61603 induced vasoconstriction was attenuated by a GPR55-dependent mechanism. Conversely, GPR55-mediated vasorelaxation was not altered by pharmacological blockade of α-ARs with tamsulosin. While cellular studies demonstrated that GPR55 and α-AR failed to dimerize, pharmacological blockade of GPR55 altered α-AR mediated signalling and reduced ERK1/2 phosphorylation. Taken together, this study provides evidence that GPR55 and α-AR do not dimerize to form heteromers, but do interact at the signalling level to modulate the function of α-AR in the cardiovascular system.
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http://dx.doi.org/10.1016/j.bcp.2021.114560DOI Listing
June 2021

INSL5 activates multiple signalling pathways and regulates GLP-1 secretion in NCI-H716 cells.

J Mol Endocrinol 2018 04;60(3):213-224

Drug Discovery BiologyMonash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia.

Insulin-like peptide 5 (INSL5) is a newly discovered gut hormone expressed in colonic enteroendocrine L-cells but little is known about its biological function. Here, we show using RT-qPCR and hybridisation that mRNA is highly expressed in the mouse colonic mucosa, colocalised with proglucagon immunoreactivity. In comparison, mRNA for RXFP4 (the cognate receptor for INSL5) is expressed in various mouse tissues, including the intestinal tract. We show that the human enteroendocrine L-cell model NCI-H716 cell line, and goblet-like colorectal cell lines SW1463 and LS513 endogenously express Stimulation of NCI-H716 cells with INSL5 produced phosphorylation of ERK1/2 (Thr/Tyr), AKT (Thr and Ser) and S6RP (Ser) and inhibited cAMP production but did not stimulate Ca release. Acute INSL5 treatment had no effect on GLP-1 secretion mediated by carbachol or insulin, but modestly inhibited forskolin-stimulated GLP-1 secretion in NCI-H716 cells. However, chronic INSL5 pre-treatment (18 h) increased basal GLP-1 secretion and prevented the inhibitory effect of acute INSL5 administration. LS513 cells were found to be unresponsive to INSL5 despite expressing Another enteroendocrine L-cell model, mouse GLUTag cells did not express detectable levels of and were unresponsive to INSL5. This study provides novel insights into possible autocrine/paracrine roles of INSL5 in the intestinal tract.
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http://dx.doi.org/10.1530/JME-17-0152DOI Listing
April 2018

Structure-function analyses of a pertussis-like toxin from pathogenic reveal a distinct mechanism of inhibition of trimeric G-proteins.

J Biol Chem 2017 09 29;292(36):15143-15158. Epub 2017 Jun 29.

the Department of Animal, Plant and Soil Science and Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia

Pertussis-like toxins are secreted by several bacterial pathogens during infection. They belong to the AB virulence factors, which bind to glycans on host cell membranes for internalization. Host cell recognition and internalization are mediated by toxin B subunits sharing a unique pentameric ring-like assembly. Although the role of pertussis toxin in whooping cough is well-established, pertussis-like toxins produced by other bacteria are less studied, and their mechanisms of action are unclear. Here, we report that some extra-intestinal pathogens ( those that reside in the gut but can spread to other bodily locations) encode a pertussis-like toxin that inhibits mammalian cell growth We found that this protein, Plt, is related to toxins produced by both nontyphoidal and typhoidal serovars. Pertussis-like toxins are secreted as disulfide-bonded heterohexamers in which the catalytic ADP-ribosyltransferase subunit is activated when exposed to the reducing environment in mammalian cells. We found here that the reduced Plt exhibits large structural rearrangements associated with its activation. We noted that inhibitory residues tethered within the NAD-binding site by an intramolecular disulfide in the oxidized state dissociate upon the reduction and enable loop restructuring to form the nucleotide-binding site. Surprisingly, although pertussis toxin targets a cysteine residue within the α subunit of inhibitory trimeric G-proteins, we observed that activated Plt toxin modifies a proximal lysine/asparagine residue instead. In conclusion, our results reveal the molecular mechanism underpinning activation of pertussis-like toxins, and we also identified differences in host target specificity.
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http://dx.doi.org/10.1074/jbc.M117.796094DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5592689PMC
September 2017

ML290 is a biased allosteric agonist at the relaxin receptor RXFP1.

Sci Rep 2017 06 7;7(1):2968. Epub 2017 Jun 7.

Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia.

Activation of the relaxin receptor RXFP1 has been associated with improved survival in acute heart failure. ML290 is a small molecule RXFP1 agonist with simple structure, long half-life and high stability. Here we demonstrate that ML290 is a biased agonist in human cells expressing RXFP1 with long-term beneficial actions on markers of fibrosis in human cardiac fibroblasts (HCFs). ML290 did not directly compete with orthosteric relaxin binding and did not affect binding kinetics, but did increase binding to RXFP1. In HEK-RXFP1 cells, ML290 stimulated cAMP accumulation and p38MAPK phosphorylation but not cGMP accumulation or ERK1/2 phosphorylation although prior addition of ML290 increased p-ERK1/2 responses to relaxin. In human primary vascular endothelial and smooth muscle cells that endogenously express RXFP1, ML290 increased both cAMP and cGMP accumulation but not p-ERK1/2. In HCFs, ML290 increased cGMP accumulation but did not affect p-ERK1/2 and given chronically activated MMP-2 expression and inhibited TGF-β1-induced Smad2 and Smad3 phosphorylation. In vascular cells, ML290 was 10x more potent for cGMP accumulation and p-p38MAPK than for cAMP accumulation. ML290 caused strong coupling of RXFP1 to Gα and Gα but weak coupling to Gα. ML290 exhibited signalling bias at RXFP1 possessing a signalling profile indicative of vasodilator and anti-fibrotic properties.
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http://dx.doi.org/10.1038/s41598-017-02916-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5462828PMC
June 2017

The actions of relaxin family peptides on signal transduction pathways activated by the relaxin family peptide receptor RXFP4.

Naunyn Schmiedebergs Arch Pharmacol 2017 Jan 26;390(1):105-111. Epub 2016 Nov 26.

Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia.

The relaxin family peptide receptor 4 (RXFP4) is a G protein-coupled receptor (GPCR) expressed in the colorectum with emerging roles in metabolism and appetite regulation. It is activated by its cognate ligand insulin-like peptide 5 (INSL5) that is expressed in enteroendocrine L cells in the gut. Whether other evolutionarily related peptides such as relaxin-2, relaxin-3, or INSL3 activate RXFP4 signal transduction mechanisms with a pattern similar to or distinct from INSL5 is still unclear. In this study, we compare the signaling pathways activated by various relaxin family peptides to INSL5. We found that, like INSL5, relaxin-3 activated ERK1/2, p38MAPK, Akt, and S6RP phosphorylations leading to increased cell proliferation and also caused GRK and β-arrestin-mediated receptor internalization. Interestingly, relaxin-3 was slightly more potent than INSL5 in ERK1/2 and Akt phosphorylations, but both peptides were almost equipotent in adenylyl cyclase inhibition, S6RP phosphorylation, and cell proliferation. In addition, relaxin-3 showed greater efficacy only in Akt phosphorylation but not in the other pathways investigated. In contrast, no signaling activity or receptor internalization mechanisms were observed following relaxin-2 and INSL3. In conclusion, relaxin-3 is a high-efficacy agonist at RXFP4 with a comparable signal transduction profile to INSL5.
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http://dx.doi.org/10.1007/s00210-016-1321-8DOI Listing
January 2017

Signal transduction pathways activated by insulin-like peptide 5 at the relaxin family peptide RXFP4 receptor.

Br J Pharmacol 2017 05 13;174(10):1077-1089. Epub 2016 Jul 13.

Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.

Background And Purpose: Insulin-like peptide 5 (INSL5) is a two-chain, three-disulfide-bonded peptide of the insulin/relaxin superfamily, uniquely expressed in enteroendocrine L-cells of the colon. It is the cognate ligand of relaxin family peptide RXFP4 receptor that is mainly expressed in the colorectum and enteric nervous system. This study identifies new signalling pathways activated by INSL5 acting on RXFP4 receptors.

Experimental Approach: INSL5/RXFP4 receptor signalling was investigated using AlphaScreen® proximity assays. Recruitment of Gα proteins by RXFP4 receptors was determined by rescue of Pertussis toxin (PTX)-inhibited cAMP and ERK1/2 responses following transient transfection of PTX-insensitive Gα C351I mutants. Cell proliferation was studied with bromodeoxyuridine. RXFP4 receptor interactions with β-arrestins, GPCR kinase 2 (GRK2), KRas and Rab5a was assessed with real-time BRET. Gene expression was investigated using real-time quantitative PCR. Insulin release was measured using HTRF and intracellular Ca flux monitored in a Flexstation® using Fluo-4-AM.

Key Results: INSL5 inhibited forskolin-stimulated cAMP accumulation and increased phosphorylation of ERK1/2, p38MAPK, Akt Ser , Akt Thr and S6 ribosomal protein. cAMP and ERK1/2 responses were abolished by PTX and rescued by mGα , mGα and mGα and to a lesser extent mGα and mGα . RXFP4 receptors interacted with GRK2 and β-arrestins, moved towards Rab5a and away from KRas, indicating internalisation following receptor activation. INSL5 inhibited glucose-stimulated insulin secretion and Ca mobilisation in MIN6 insulinoma cells and forskolin-stimulated cAMP accumulation in NCI-H716 enteroendocrine cells.

Conclusions And Implications: Knowledge of signalling pathways activated by INSL5 at RXFP4 receptors is essential for understanding the biological roles of this novel gut hormone.

Linked Articles: This article is part of a themed section on Recent Progress in the Understanding of Relaxin Family Peptides and their Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.10/issuetoc.
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http://dx.doi.org/10.1111/bph.13522DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5406383PMC
May 2017