Cellular trafficking and functional characterisation of the human glucagon like peptide-1 receptor.

The binding of glucagon like peptide-1 (GLP-1] to its receptor, the GLP-1 receptor (GLP-IR), results in insulin secretion from pancreatic beta-cells. This makes the receptor an important drug target for type 2 diabetes. The GLP-IR is a family B G-protein coupled receptor (GPCR) and functions at the cell surface by coupling to Galphas and Galphaq pathways and causing ERK phosphorylation. The objective of this study was to analyse trafficking, activity and internalisation of GLP-IR at the cellular and molecular level. The human GLP-IR (hGLP-1R) N-terminus is required for trafficking and maturation. This study demonstrated the importance of signal peptide (SP] cleavage, N-linked glycosylation and the hydrophobic region after the SP [HRASP] within the N-terminus of the hGLP-1R for cell surface expression. Due to difficulties in peptide drugs, orally active small molecule agonists of the GLP-IR are of high importance. Small molecule allosteric agonists, compounds 2 and B, were found to cause cAMP production similar to orthosteric GLP-1, but not intracellular Ca2+ accumulation, ERK phosphorylation or internalisation of the receptor. Compounds 2 and B binding to the GLP-IR inhibits GLP-1 internalisation, intracellular Ca2+ accumulation and ERK phosphorylation of the receptor. Agonist induced hGLP-1R internalisation is important for insulin secretion. Inhibition of the G?q pathway but not the Gas pathway reduced hGLP-1R internalisation. Consistent with this, the hGLP-1R T149M mutant and compounds 2 and B, which activate only the Gas pathway, failed to induce hGLP-1R internalisation. Chemical inhibitors of the Galphaq pathway significantly reduced agonist induced hGLP-1R internalisation and suppressed ERK phosphorylation demonstrating phosphorylated ERK acts downstream of the Galphaq pathway in hGLP-1R internalisation. Finally, distinct regions within the C-terminus of hGLP-1R required for its cell surface expression, activity and internalisation were identified. Residues 411- 418, 419-430 and 431-450 are essential for hGLP-1R cell surface expression, activity and internalisation, respectively

Pattern recognition receptors in fungal immunity

Over the last decade, invasive fungal infections have emerged as a growing threat to human health worldwide and novel treatment strategies are urgently needed. In this context, investigations into host-pathogen interactions represent an important and promising field of research. Antigen presenting cells such as macrophages and dendritic cells are strategically located at the frontline of defence against potential invaders. Importantly, these cells express germline encoded pattern recognition receptors (PRRs), which sense conserved entities from pathogens and orchestrate innate immune responses. Herein, we review the latest findings regarding the biology and functions of the different classes of PRRs involved in pathogenic fungal recognition. We also discuss recent literature on PRR collaboration/crosstalk and the mechanisms involved in inhibiting/regulating PRR signalling. Finally, we discuss how the accumulated knowledge on PRR biology, especially Dectin-1, has been used for the design of new immunotherapies against fungal infections

Dependence on Mincle and Dectin-2 Varies With Multiple Candida Species During Systemic Infection

FUNDING SO was supported by a Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (Grant No. 099953/Z/12/Z) and by a Wellcome Trust Cross-Disciplinary Award. NG acknowledges Wellcome Trust support of a Senior Investigator (101873/Z/13/Z), Collaborative (200208/A/15/Z) and Strategic Awards (097377/Z11/Z) and the MRC Centre for Medical Mycology (MR/N006364/2). PT was funded by a Wellcome Trust Investigator Award (107964/Z/15/Z) and the UK Dementia Research Institute. ACKNOWLEDGMENTS We wish to acknowledge the NIH-sponsored Mutant Mouse Regional Resource Center (MMRRC) National System as the source of genetically altered mice (C57BL/6-Clec4et m1. 1C fg /Mmucd 031936-UCD) for use in this study. The mice were produced and deposited to the MMRRC by the Consortium for Functional Glycomics supported by the National Institute of General Medical Sciences (GM62116). We also thank the Microscopy and Histology Core Facility at the University of Aberdeen for expert assistance with TEM.Peer reviewedPublisher PD

Ghrelin-AMPK Signaling Mediates the Neuroprotective Effects of Calorie Restriction in Parkinson's Disease

Jacqeline Bayliss, Romana Stark, Moyra Lemus, Vanessa Santos, Aiysha Thompson, Daniel Rees, Sandra Galic, John Elsworth, Bruce Kemp, Jeffrey Davies, and Zane Andrew

The protective effect of inflammatory monocytes during systemic C. albicans infection is dependent on collaboration between C-type lectin-like receptors

Acknowledgments The authors wish to acknowledge the NIH-sponsored Mutant Mouse Regional Resource Center (MMRRC) National System as the source of genetically-altered mice (C57BL/6-Clec4etm1.1Cfg/Mmucd 031936-UCD) for use in this study. The mice were produced and deposited to the MMRRC by the Consortium for Functional Glycomics supported by the National Institute of General Medical Sciences (GM62116). We would like to thank Catherine Neiseryan and Ann Kift-Morgan for cell sorting. We would like to thank Wales Gene Park for providing computer resources that assisted this research. Funding: SJO was funded by a Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (Grant Number 099953/Z/12/Z) and by a Wellcome Trust ISSF Cross-Disciplinary Award. LCD is supported by a Henry Wellcome Trust Postdoctoral Fellowship (103973/Z/14/Z). CL is supported by a Kidney Research UK/MedImmune Joint Fellowship Award (PDF_006_20151127). GDB is funded by a Wellcome Trust Investigator Award (102705) and the MRC Centre for Medical Mycology and the University of Aberdeen (MR/N006364/1). IRH is supported by a Wellcome Trust Senior Research Fellowship (207503/Z/17/Z). PRT is supported by a Wellcome Trust Investigator Award (107964/Z/15/Z) and the UK Dementia Research Institute. Funding URLs: https://wellcome.ac.uk/ https://royalsociety.org/ https://www.kidneyresearchuk.org/ https://mrc.ukri.org/ https://ukdri.ac.uk/ The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Data Availability: All relevant data apart from RNAseq files are within the manuscript and its Supporting Information files. RNAseq data files are available from ArrayExpress (https://www.ebi.ac.uk/arrayexpress/), (accession number E-MTAB-8030).Peer reviewedPublisher PD

Agonist-induced internalisation of the glucagon-like peptide-1 receptor is mediated by the Gαq pathway

The glucagon like peptide-1 receptor (GLP-1R) is a G-protein coupled receptor (GPCR) and an important target in the treatment of type 2 diabetes mellitus (T2DM). Upon stimulation with agonist, the GLP-1R signals through both Gαs and Gαq coupled pathways to stimulate insulin secretion. The agonist induced GLP-1R internalisation has recently been shown to be important for insulin secretion. However, the molecular mechanisms underlying GLP-1R internalisation remain unknown. The aim of this study was to determine the role of GLP-1R downstream signalling pathways in its internalisation. Agonist induced human GLP-1R (hGLP-1R) internalisation and activity were examined using a number of techniques including immunoblotting, ELISA, immunofluorescence, and luciferase assays to determine cAMP production, intracellular Ca2+ accumulation and ERK phosphorylation. Agonist induced hGLP-1R internalisation is dependent on caveolin-1 and dynamin. Inhibition of the Gαq pathway but not the Gαs pathway affected hGLP-1R internalisation. Consistent with this, hGLP-1R mutant T149 M and small molecule agonists (compound 2 and compound B), which activate only the Gαs pathway, failed to induce internalisation of the receptor. Chemical inhibitors of the Gαq pathway, PKC and ERK phosphorylation significantly reduced agonist induced hGLP-1R internalisation. These inhibitors also suppressed agonist induced ERK1/2 phosphorylation demonstrating that the phosphorylated ERK acts downstream of the Gαq pathway in the hGLP-1R internalisation. In summary, agonist induced hGLP-1R internalisation is mediated by the Gαq pathway. The internalised hGLP-1R stimulates insulin secretion from pancreatic β-cells, indicating the importance of GLP-1 internalisation for insulin secretion

Molecular Characterisation of Small Molecule Agonists Effect on the Human Glucagon Like Peptide-1 Receptor Internalisation

The glucagon-like peptide receptor (GLP-1R), which is a G-protein coupled receptor (GPCR), signals through both Gαs and Gαq coupled pathways and ERK phosphorylation to stimulate insulin secretion. The aim of this study was to determine molecular details of the effect of small molecule agonists, compounds 2 and B, on GLP-1R mediated cAMP production, intracellular Ca2+ accumulation, ERK phosphorylation and its internalisation. In human GLP-1R (hGLP-1R) expressing cells, compounds 2 and B induced cAMP production but caused no intracellular Ca2+ accumulation, ERK phosphorylation or hGLP-1R internalisation. GLP-1 antagonists Ex(9-39) and JANT-4 and the orthosteric binding site mutation (V36A) in hGLP-1R failed to inhibit compounds 2 and B induced cAMP production, confirming that their binding site distinct from the GLP-1 binding site on GLP-1R. However, K334A mutation of hGLP-1R, which affects Gαs coupling, inhibited GLP-1 as well as compounds 2 and B induced cAMP production, indicating that GLP-1, compounds 2 and B binding induce similar conformational changes in the GLP-1R for Gαs coupling. Additionally, compound 2 or B binding to the hGLP-1R had significantly reduced GLP-1 induced intracellular Ca2+ accumulation, ERK phosphorylation and hGLP-1R internalisation. This study illustrates pharmacology of differential activation of GLP-1R by GLP-1 and compounds 2 and B

IL-27 Induced by Select Candida spp. via TLR7/NOD2 Signaling and IFN-β Production Inhibits Fungal Clearance

Candida spp. elicit cytokine production downstream of various pathogen recognition receptors (PRRs) including C-type lectin-like receptors (CLRs), Toll-like receptors (TLRs) and nucleotide oligomerisation domain (NOD)-like receptors (NLRs). IL-12 family members, IL-12p70 and IL-23, are important for host immunity against Candida spp. Herein we show that IL-27, another IL-12 family member, is produced by myeloid cells in response to select Candida spp. We demonstrate a novel mechanism for C. parapsilosis-mediated induction of IL-27 in a TLR7-, MyD88- and NOD2-dependent manner. Our data revealed that IFN-β is induced by C. parapsilosis, which in turn signals through the interferon-α/β receptor (IFNAR) and STAT1/2 to induce IL-27. Moreover, IL 27R (WSX-1) deficient mice systemically infected with C. parapsilosis displayed enhanced pathogen clearance compared to WT mice. This was associated with increased levels of pro-inflammatory cytokines in the serum and increased IFN-γ and IL-17 responses in the spleens of IL-27R deficient mice. Thus our data define a novel link between C. parapsilosis, TLR7, NOD2, IFN-β and IL-27 and we have identified an important role for IL-27 in the immune response against C. parapsilosis. Overall these findings demonstrate an important mechanism for the suppression of protective immune responses during infection with C. parapsilosis, which has potential relevance for infections with other fungal pathogens

A human Dectin-2 deficiency associated with invasive aspergillosis

Immunocompromised patients are highly susceptible to invasive aspergillosis. Herein, we identified a homozygous deletion mutation (507 del C) resulting in a frameshift (N170I) and early stop codon in the fungal binding Dectin-2 receptor, in an immunocompromised patient. The mutated form of Dectin-2 was weakly expressed, did not form clusters at/near the cell surface and was functionally defective. PBMCs from this patient were unable to mount a cytokine (TNF, IL-6) response to A. fumigatus and this first identified Dectin-2-deficient patient succumbed to invasive aspergillosis

Emerging IL-12 family cytokines in the fight against fungal infections

Invasive fungal infections cause approximately 1.5 million deaths per year worldwide and are a growing threat to human health. Current anti-fungal therapies are often insufficient, therefore studies into host-pathogen interactions are critical for the development of novel therapies to improve mortality rates. Myeloid cells, such as macrophages and dendritic cells, express pattern recognition receptor (PRRs), which are important for fungal recognition. Engagement of these PRRs by fungal pathogens induces multiple cytokines, which in turn activate T effector responses. Interleukin (IL)-12 family members (IL-12p70, IL-23, IL-27 and IL-35) link innate immunity with the development of adaptive immunity and are also important for regulating T cell responses. IL-12 and IL-23 have established roles during anti-fungal immunity, whereas emerging roles for IL-27 and IL-35 have recently been reported. Here, we discuss the IL-12 family, focusing on IL-27 and IL-35 during anti-fungal immune responses to pathogens such as Candida and Aspergillus