scholarly journals Fungal G-Protein-Coupled Receptors: A Promising Mediator of the Impact of Extracellular Signals on Biosynthesis of Ochratoxin A

2021 ◽  
Vol 12 ◽  
Author(s):  
Jing Gao ◽  
Xinge Xu ◽  
Kunlun Huang ◽  
Zhihong Liang
Keyword(s):  
G Protein ◽  
Ochratoxin A ◽  
G Protein Coupled Receptors ◽  
Aspergillus Ochraceus ◽  
Transmembrane Receptors ◽  
Environmental Signals ◽  
Extracellular Signals ◽  
Fungal Biology ◽  
The Impact ◽  
G Protein Coupled

G-protein-coupled receptors (GPCRs) are transmembrane receptors involved in transducing signals from the external environment inside the cell, which enables fungi to coordinate cell transport, metabolism, and growth to promote their survival, reproduction, and virulence. There are 14 classes of GPCRs in fungi involved in sensing various ligands. In this paper, the synthesis of mycotoxins that are GPCR-mediated is discussed with respect to ligands, environmental stimuli, and intra-/interspecific communication. Despite their apparent importance in fungal biology, very little is known about the role of ochratoxin A (OTA) biosynthesis by Aspergillus ochraceus and the ligands that are involved. Fortunately, increasing evidence shows that the GPCR that involves the AF/ST (sterigmatocystin) pathway in fungi belongs to the same genus. Therefore, we speculate that GPCRs play an important role in a variety of environmental signals and downstream pathways in OTA biosynthesis. The verification of this inference will result in a more controllable GPCR target for control of fungal contamination in the future.

Glucagon counteracts interleukin-6-dependent gene expression by redundant action of Epac and PKA

2011 ◽  
Vol 392 (12) ◽  
pp. 1123-1134 ◽  
Author(s):  
Christina Khouri ◽  
Anna Dittrich ◽  
Sara Dutton Sackett ◽  
Bernd Denecke ◽  
Christian Trautwein ◽  
...  
Keyword(s):  
Gene Expression ◽  
G Protein ◽  
Acute Phase ◽  
Interleukin 6 ◽  
Biological Response ◽  
Underlying Mechanism ◽  
G Protein Coupled Receptors ◽  
Counterregulatory Hormones ◽  
The Impact ◽  
G Protein Coupled

AbstractInflammation is the biological response to injurious stimuli. In the initial phase of the inflammatory process, interleukin-6 (IL-6) is the main inducer of acute phase protein expression in the liver. A prolonged acute phase response is characterised by a disturbed glucose homeostasis and elevated levels of IL-6, insulin, and counterregulatory hormones such as glucagon. Several studies deal with the impact of IL-6 on glucagon-dependent gene expression. In contrast, only very little is known about the influence of G-protein-coupled receptors on IL-6 signalling. Therefore, the aim of this study is to elucidate the regulation of IL-6-induced gene expression by glucagon. We could reveal a novel mechanism of negative regulation of IL-6-induced MAP kinase activation by glucagon in primary murine hepatocytes. IL-6-dependent induction of the ERK-dependent target geneTfpi2, coding for a Kunitz-type serine protease inhibitor, was strongly down-regulated by glucagon treatment. Studying the underlying mechanism revealed a redundant action of the signalling molecules exchange protein activated by cyclic AMP (Epac) and protein kinase A. The metabolic hormone glucagon interferes in IL-6-induced gene expression. This observation is indicative for a regulatory role of G-protein-coupled receptors in the IL-6-dependent inflammatory response.

scholarly journals Mycobacteria Manipulate G-Protein-Coupled Receptors to Increase Mucosal Rac1 Expression in the Lungs

2016 ◽  
Vol 9 (3) ◽  
pp. 318-329 ◽  
Author(s):  
Nader Alaridah ◽  
Nataliya Lutay ◽  
Erik Tenland ◽  
Anna Rönnholm ◽  
Oskar Hallgren ◽  
...  
Keyword(s):  
G Protein ◽  
Airway Epithelial Cells ◽  
G Protein Coupled Receptors ◽  
The Body ◽  
Airway Epithelial ◽  
Mucosal Vaccination ◽  
Mapk Signalling Pathway ◽  
The Impact ◽  
G Protein Coupled ◽  
Rac1 Expression

Mycobacterium bovis bacille Calmette-Guérin (BCG) is currently the only approved vaccine against tuberculosis (TB). BCG mimics M. tuberculosis (Mtb) in its persistence in the body and is used as a benchmark to compare new vaccine candidates. BCG was originally designed for mucosal vaccination, but comprehensive knowledge about its interaction with epithelium is currently lacking. We used primary airway epithelial cells (AECs) and a murine model to investigate the initial events of mucosal BCG interactions. Furthermore, we analysed the impact of the G-protein-coupled receptors (GPCRs), CXCR1 and CXCR2, in this process, as these receptors were previously shown to be important during TB infection. BCG infection of AECs induced GPCR-dependent Rac1 up-regulation, resulting in actin redistribution. The altered distribution of the actin cytoskeleton involved the MAPK signalling pathway. Blocking of the CXCR1 or CXCR2 prior to infection decreased Rac1 expression, and increased epithelial transcriptional activity and epithelial cytokine production. BCG infection did not result in epithelial cell death as measured by p53 phosphorylation and annexin. This study demonstrated that BCG infection of AECs manipulated the GPCRs to suppress epithelial signalling pathways. Future vaccine strategies could thus be improved by targeting GPCRs.

scholarly journals Disentangling bias between Gq, GRK2, and arrestin3 recruitment to the M3 muscarinic acetylcholine receptor

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Anja Floeser ◽  
Katharina Becker ◽  
Evi Kostenis ◽  
Gabriele König ◽  
Cornelius Krasel ◽  
...  
Keyword(s):  
G Protein ◽  
Acetylcholine Receptor ◽  
Rank Order ◽  
Muscarinic Acetylcholine Receptor ◽  
G Protein Coupled Receptors ◽  
Effector Proteins ◽  
Muscarinic Acetylcholine ◽  
Extracellular Signals ◽  
G Protein Coupled ◽  
Different Levels

G protein-coupled receptors (GPCRs) transmit extracellular signals to the inside by activation of intracellular effector proteins. Different agonists can promote differential receptor-induced signaling responses – termed bias – potentially by eliciting different levels of recruitment of effector proteins. As activation and recruitment of effector proteins might influence each other, thorough analysis of bias is difficult. Here, we compared the efficacy of seven agonists to induce G protein, G protein-coupled receptor kinase 2 (GRK2), as well as arrestin3 binding to the muscarinic acetylcholine receptor M3 by utilizing FRET-based assays. In order to avoid interference between these interactions, we studied GRK2 binding in the presence of inhibitors of Gi and Gq proteins and analyzed arrestin3 binding to prestimulated M3 receptors to avoid differences in receptor phosphorylation influencing arrestin recruitment. We measured substantial differences in the agonist efficacies to induce M3R-arrestin3 versus M3R-GRK2 interaction. However, the rank order of the agonists for G protein- and GRK2-M3R interaction was the same, suggesting that G protein and GRK2 binding to M3R requires similar receptor conformations, whereas requirements for arrestin3 binding to M3R are distinct.

scholarly journals Noncanonical scaffolding of Gαi and β-arrestin by G protein-coupled receptors

2019 ◽  
Author(s):  
Jeffrey S. Smith ◽  
Thomas F. Pack ◽  
Asuka Inoue ◽  
Claudia Lee ◽  
Xinyu Xiong ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Coupled Receptors ◽  
Environmental Signals ◽  
Extracellular Signal Regulated Kinase ◽  
Intracellular Signals ◽  
Extracellular Signal ◽  
Extracellular Stimuli ◽  
Protein Isoform ◽  
Sense And Respond ◽  
G Protein Coupled

SummaryG-protein-coupled receptors (GPCRs) enable cells to sense and respond appropriately to hormonal and environmental signals, and are a target of ~30% of all FDA-approved medications. Canonically, each GPCR couples to distinct Gα proteins, such as Gαs, Gαi, Gαq or Gα12/13, as well as β-arrestins. These transducer proteins translate and integrate extracellular stimuli sensed by GPCRs into intracellular signals through what are broadly considered separable signalling pathways. However, the ability of Gα proteins to directly interact with β-arrestins to integrate signalling has not previously been appreciated. Here we show a novel interaction between Gαi protein family members and β-arrestin. Gαi:β-arrestin complexes were formed by all GPCRs tested, regardless of their canonical G protein isoform coupling, and could bind both GPCRs as well as the extracellular signal-regulated kinase (ERK). This novel paradigm of Gαi:β-arrestin scaffolds enhances our understanding of GPCR signalling.

scholarly journals Pathological AT1R-B2R Protein Aggregation and Preeclampsia

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2609
Author(s):  
Ursula Quitterer ◽  
Said AbdAlla
Keyword(s):  
Risk Factors ◽  
Complex Formation ◽  
Protein Aggregation ◽  
G Protein ◽  
Protein Complex ◽  
G Protein Coupled Receptors ◽  
Protein Complex Formation ◽  
The Impact ◽  
G Protein Coupled ◽  
Gpcr Protein

Preeclampsia is one of the most frequent and severe complications of pregnancy. Symptoms of preeclampsia usually occur after 20 weeks of pregnancy and include hypertension and kidney dysfunction with proteinuria. Up to now, delivery of the infant has been the most effective and life-saving treatment to alleviate symptoms of preeclampsia because a causative treatment does not exist, which could prolong a pregnancy complicated with preeclampsia. Preeclampsia is a complex medical condition, which is attributed to a variety of different risk factors and causes. Risk factors account for insufficient placentation and impaired vasculogenesis and finally culminate in this life-threatening condition of pregnancy. Despite progress, many pathomechanisms and causes of preeclampsia are still incompletely understood. In recent years, it was found that excessive protein complex formation between G-protein-coupled receptors is a common sign of preeclampsia. Specifically, the aberrant heteromerization of two vasoactive G-protein-coupled receptors (GPCRs), the angiotensin II AT1 receptor and the bradykinin B2 receptor, is a causative factor of preeclampsia symptoms. Based on this knowledge, inhibition of abnormal GPCR protein complex formation is an experimental treatment approach of preeclampsia. This review summarizes the impact of pathological GPCR protein aggregation on symptoms of preeclampsia and delineates potential new therapeutic targets.

scholarly journals The repertoire of Adhesion G protein-coupled receptors in adipocytes and their functional relevance

2020 ◽  
Vol 44 (10) ◽  
pp. 2124-2136 ◽  
Author(s):  
Tomáš Suchý ◽  
Christian Zieschang ◽  
Yulia Popkova ◽  
Isabell Kaczmarek ◽  
Juliane Weiner ◽  
...  
Keyword(s):  
G Protein ◽  
Lipid Accumulation ◽  
Adipocyte Differentiation ◽  
G Protein Coupled Receptors ◽  
Adipose Tissues ◽  
Functional Relevance ◽  
And Function ◽  
Adhesion Gpcr ◽  
The Impact ◽  
G Protein Coupled

Abstract Background G protein-coupled receptors (GPCR) are well-characterized regulators of a plethora of physiological functions among them the modulation of adipogenesis and adipocyte function. The class of Adhesion GPCR (aGPCR) and their role in adipose tissue, however, is poorly studied. With respect to the demand for novel targets in obesity treatment, we present a comprehensive study on the expression and function of this enigmatic GPCR class during adipogenesis and in mature adipocytes. Methods The expression of all aGPCR representatives was determined by reanalyzing RNA-Seq data and by performing qPCR in different mouse and human adipose tissues under low- and high-fat conditions. The impact of aGPCR expression on adipocyte differentiation and lipid accumulation was studied by siRNA-mediated knockdown of all expressed members of this receptor class. The biological characteristics and function of mature adipocytes lacking selected aGPCR were analyzed by mass spectrometry and biochemical methods (lipolysis, glucose uptake, adiponectin secretion). Results More than ten aGPCR are significantly expressed in visceral and subcutaneous adipose tissues and several aGPCR are differentially regulated under high-caloric conditions in human and mouse. Receptor knockdown of six receptors resulted in an impaired adipogenesis indicating their expression is essential for proper adipogenesis. The altered lipid composition was studied in more detail for two representatives, ADGRG2/GPR64 and ADGRG6/GPR126. While GPR126 is mainly involved in adipocyte differentiation, GPR64 has an additional role in mature adipocytes by regulating metabolic processes. Conclusions Adhesion GPCR are significantly involved in qualitative and quantitative adipocyte lipid accumulation and can control lipolysis. Factors driving adipocyte formation and function are governed by signaling pathways induced by aGPCR yielding these receptors potential targets for treating obesity.

scholarly journals G-protein-coupled receptors, cholesterol and palmitoylation: facts about fats

2009 ◽  
Vol 42 (5) ◽  
pp. 371-379 ◽  
Author(s):  
Bice Chini ◽  
Marco Parenti
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
Membrane Domains ◽  
Functional Features ◽  
Gpcr Structure ◽  
Carboxyl Terminal ◽  
The Impact ◽  
G Protein Coupled ◽  
Partner Proteins

G-protein-coupled receptors (GPCRs) are integral membrane proteins, hence it is not surprising that a number of their structural and functional features are modulated by both proteins and lipids. The impact of interacting proteins and lipids on the assembly and signalling of GPCRs has been extensively investigated over the last 20–30 years, and a further impetus has been given by the proposal that GPCRs and/or their immediate signalling partners (G proteins) can partition within plasma membrane domains, termed rafts and caveolae, enriched in glycosphingolipids and cholesterol. The high content of these specific lipids, in particular of cholesterol, in the vicinity of GPCR transmembranes can affect GPCR structure and/or function. In addition, most GPCRs are post-translationally modified with one or more palmitic acid(s), a 16-carbon saturated fatty acid, covalently bound to cysteine(s) localised in the carboxyl-terminal cytoplasmic tail. The insertion of palmitate into the cytoplasmic leaflet of the plasma membrane can create a fourth loop, thus profoundly affecting GPCR structure and hence the interactions with intracellular partner proteins. This review briefly highlights how lipids of the membrane and the receptor themselves can influence GPCR organisation and functioning.

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