scholarly journals Proteomic Characterization of the Cellular Effects of AhR Activation by Microbial Tryptophan Catabolites in Endotoxin-Activated Human Macrophages

2021 ◽  
Vol 18 (19) ◽  
pp. 10336
Author(s):  
Katharina Walter ◽  
Henning Grosskopf ◽  
Isabel Karkossa ◽  
Martin von Bergen ◽  
Kristin Schubert
Keyword(s):  
Bacterial Infections ◽  
Immune Cell ◽  
Dependent Manner ◽  
Cellular Effects ◽  
Cellular Processes ◽  
Commensal Microbiota ◽  
Aryl Hydrocarbon ◽  
Tryptophan Metabolites ◽  
Tryptophan Catabolites

Sensing microbial tryptophan catabolites by the aryl hydrocarbon receptor (AhR) plays a pivotal role in host-microbiome homeostasis by modulating the host immune response. Nevertheless, the involved cellular processes triggered by the metabolites are mainly unknown. Here, we analyzed proteomic changes in macrophages after treatment with the tryptophan metabolites indole-3-acetic acid (I3AA) or indole-3-aldehyde (IAld), as well as the prototypic exogenous AhR-ligand benzo(a)pyrene (BaP) in the absence and presence of lipopolysaccharide (LPS) to identify affected cellular processes and pathways. The AhR-ligands regulated metabolic and immunologic processes in dependency of LPS co-stimulation. All investigated ligands time-dependently enhanced fatty acid β-oxidation. Differences due to the combination with LPS were observed for all three ligands. Additionally, oxidative phosphorylation was significantly increased by IAld and I3AA in a time and LPS-dependent manner. Immunoregulatory processes were affected in distinct ways. While BaP and I3AA up-regulated IL-8 signaling, IL-6 signaling was decreased by IAld. BaP decreased the inflammasome pathway. Thus, AhR-ligand-dependent regulations were identified, which may modulate the response of macrophages to bacterial infections, but also the commensal microbiota through changes in immune cell signaling and metabolic pathways that may also alter functionality. These findings highlight the relevance of AhR for maintaining microbial homeostasis and, consequently, host health.

scholarly journals An acoustic platform for single-cell, high-throughput measurements of the viscoelastic properties of cells

2020 ◽  
Author(s):  
Valentin Romanov ◽  
Giulia Silvani ◽  
Huiyu Zhu ◽  
Charles D Cox ◽  
Boris Martinac
Keyword(s):  
Mechanical Properties ◽  
Single Cell ◽  
High Throughput ◽  
Single Cells ◽  
Adherent Cells ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Membrane Cytoskeleton ◽  
Change Temperature

ABSTRACTCellular processes including adhesion, migration and differentiation are governed by the distinct mechanical properties of each cell. Importantly, the mechanical properties of individual cells can vary depending on local physical and biochemical cues in a time-dependent manner resulting in significant inter-cell heterogeneity. While several different methods have been developed to interrogate the mechanical properties of single cells, throughput to capture this heterogeneity remains an issue. While new high-throughput techniques are slowly emerging, they are primarily aimed at characterizing cells in suspension, whereas high-throughput measurements of adherent cells have proven to be more challenging. Here, we demonstrate single-cell, high-throughput characterization of adherent cells using acoustic force spectroscopy. We demonstrate that cells undergo marked changes in viscoelasticity as a function of temperature, the measurements of which are facilitated by a closed microfluidic culturing environment that can rapidly change temperature between 21 °C and 37 °C. In addition, we show quantitative differences in cells exposed to different pharmacological treatments specifically targeting the membrane-cytoskeleton interface. Further, we utilize the high-throughput format of the AFS to rapidly probe, in excess of 1000 cells, three different cell-lines expressing different levels of a mechanosensitive protein, Piezo1, demonstrating the ability to differentiate between cells based on protein expression levels.

scholarly journals Tryptophan Metabolites at the Crossroad of Immune-Cell Interaction via the Aryl Hydrocarbon Receptor: Implications for Tumor Immunotherapy

2021 ◽  
Vol 22 (9) ◽  
pp. 4644
Author(s):  
Marco Gargaro ◽  
Giorgia Manni ◽  
Giulia Scalisi ◽  
Paolo Puccetti ◽  
Francesca Fallarino
Keyword(s):  
Immune Responses ◽  
Aryl Hydrocarbon Receptor ◽  
Metabolic Pathways ◽  
Immune Cell ◽  
Tumor Immunotherapy ◽  
Cell Interaction ◽  
Qualitative And Quantitative ◽  
Adaptive Immune ◽  
Aryl Hydrocarbon ◽  
Tryptophan Metabolites

The Aryl hydrocarbon receptor (AhR) is a critical regulator of both innate and adaptive immune responses, with potent immunomodulatory effects that makes this receptor an attractive molecular target for novel therapeutics. Accumulating evidence indicates that diverse—both host’s and microbial—tryptophan metabolites profoundly regulate the immune system in the host via AhR, promoting either tolerance or immunity, largely as a function of the qualitative and quantitative nature of the metabolites being contributed by either source. Additional findings indicate that host and microbiota-derived tryptophan metabolic pathways can influence the outcome of immune responses to tumors. Here, we review recent studies on the role and modalities of AhR activation by various ligands, derived from either host-cell or microbial-cell tryptophan metabolic pathways, in the regulation of immune responses. Moreover, we highlight potential implications of those ligands and pathways in tumor immunotherapy, with particular relevance to checkpoint-blockade immune intervention strategies.

scholarly journals Modulation of Immune Responses by Nutritional Ligands of Aryl Hydrocarbon Receptor

2021 ◽  
Vol 12 ◽  
Author(s):  
Alba De Juan ◽  
Elodie Segura
Keyword(s):  
Immune Responses ◽  
Aryl Hydrocarbon Receptor ◽  
Immune Cell ◽  
Physiological Role ◽  
Mononuclear Phagocytes ◽  
Lymphoid Cells ◽  
Aryl Hydrocarbon ◽  
Tryptophan Catabolites ◽  
The Impact

Accumulating evidence indicates that nutrition can modulate the immune system through metabolites, either produced by host digestion or by microbiota metabolism. In this review, we focus on dietary metabolites that are agonists of the Aryl hydrocarbon Receptor (AhR). AhR is a ligand-activated transcription factor, initially characterized for its interaction with xenobiotic pollutants. Numerous studies have shown that AhR also recognizes indoles and tryptophan catabolites originating from dietary compounds and commensal bacteria. Here, we review recent work employing diet manipulation to address the impact of nutritional AhR agonists on immune responses, both locally in the intestine and at distant sites. In particular, we examine the physiological role of these metabolites in immune cell development and functions (including T lymphocytes, innate-like lymphoid cells, and mononuclear phagocytes) and their effect in inflammatory disorders.

scholarly journals Defining the AHR regulated transcriptome in NK cells reveal gene expression program relevant to development and function

2021 ◽  
Author(s):  
Prashant Trikha ◽  
Jena Moseman ◽  
Aarohi Thakkar ◽  
Amanda l Campbell ◽  
Ezgi Elmas ◽  
...  
Keyword(s):  
Nk Cells ◽  
Immune Cell ◽  
Altered Expression ◽  
Chip Sequencing ◽  
Cellular Processes ◽  
Aryl Hydrocarbon ◽  
Cd56 Expression ◽  
And Function ◽  
Transcriptional Elements ◽  
Expression Program

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that regulates cellular processes in cancer and immunity, including innate immune cell development and effector function. However, the transcriptional repertoire through which AHR mediates these effects remains largely unexplored. To elucidate the transcriptional elements directly regulated by AHR in NK cells, we performed RNA- and ChIP-sequencing on NK cells exposed to AHR agonist or antagonist. We show that mature peripheral blood NK cells lack AHR, but its expression is induced by Stat3 during IL-21-driven activation and proliferation, coincident with increased NCAM1 (CD56) expression resulting in a CD56bright phenotype. Compared to control conditions, NK cells expanded in the presence of the AHR antagonist, StemRegenin-1, were unaffected in proliferation or cytotoxicity, had no increase in NCAM1 transcription and maintained the CD56dim phenotype. However, it showed altered expression of 1,004 genes including those strongly associated with signaling pathways. In contrast, NK cells expanded in the presence of the AHR agonist, kynurenine, showed decreased cytotoxicity and altered expression of 97 genes including those strongly associated with oxidative stress and cellular metabolism. By overlaying these differentially expressed genes with AHR chromatin binding we identified 160 genes directly regulated by AHR, including hallmark AHR targets AHRR and CYP1B1, and known regulators of phenotype, development, metabolism, and function such as NCAM1, KIT, NQO1, and TXN. In summary, we define the AHR transcriptome in NK cells, propose a model of AHR and Stat3 coregulation, and identify potential pathways that may be targeted to overcome AHR-mediated immune suppression.

Human and rodent aryl hydrocarbon receptor (AHR): from mediator of dioxin toxicity to physiologic AHR functions and therapeutic options

2017 ◽  
Vol 398 (4) ◽  
pp. 455-464 ◽  
Author(s):  
Karl Walter Bock
Keyword(s):  
Aryl Hydrocarbon Receptor ◽  
Species Differences ◽  
Chemical Defence ◽  
Therapeutic Options ◽  
Cell Type ◽  
Aryl Hydrocarbon ◽  
Aryl Hydrocarbons ◽  
Tryptophan Metabolites ◽  
Dioxin Toxicity

Abstract Metabolism of aryl hydrocarbons and toxicity of dioxins led to the discovery of the aryl hydrocarbon receptor (AHR). Tremendous advances have been made on multiplicity of AHR signaling and identification of endogenous ligands including the tryptophan metabolites FICZ and kynurenine. However, human AHR functions are still poorly understood due to marked species differences as well as cell-type- and cell context-dependent AHR functions. Observations in dioxin-poisoned individuals may provide hints to physiologic AHR functions in humans. Based on these observations three human AHR functions are discussed: (1) Chemical defence and homeostasis of endobiotics. The AHR variant Val381 in modern humans leads to reduced AHR affinity to aryl hydrocarbons in comparison with Neanderthals and primates expressing the Ala381 variant while affinity to indoles remains unimpaired. (2) Homeostasis of stem/progenitor cells. Dioxins dysregulate homeostasis in sebocyte stem cells. (3) Modulation of immunity. In addition to microbial defence, AHR may be involved in a ‘disease tolerance defence pathway’. Further characterization of physiologic AHR functions may lead to therapeutic options.

scholarly journals Potential Effects of Indole-3-Lactic Acid, a Metabolite of Human Bifidobacteria, on NGF-Induced Neurite Outgrowth in PC12 Cells

2020 ◽  
Vol 8 (3) ◽  
pp. 398 ◽  
Author(s):  
Chyn Boon Wong ◽  
Azusa Tanaka ◽  
Tetsuya Kuhara ◽  
Jin-zhong Xiao
Keyword(s):  
Lactic Acid ◽  
Neurite Outgrowth ◽  
Pc12 Cells ◽  
Infant Health ◽  
Dependent Manner ◽  
Human Infants ◽  
Aryl Hydrocarbon ◽  
New Findings ◽  
Tryptophan Metabolites

Gut microbiota-derived tryptophan metabolites such as indole derivatives are an integral part of host metabolome that could mediate gut–brain communication and contribute to host homeostasis. We previously reported that infant-type Human-Residential Bifidobacteria (HRB) produced higher levels of indole-3-lactic acid (ILA), suggesting the former might play a specific role in microbiota–host crosstalk by producing ILA in human infants. Nonetheless, the biological meaning of bifidobacteria-derived ILA in infant health development remains obscure. Here, we sought to explore the potential role of ILA in neuronal differentiation. We examined the neurite outgrowth and acetylcholinesterase (AchE) activity of PC12 cells following exposure to ILA and NGF induction. We found that ILA substantially enhanced NGF-induced neurite outgrowth of PC12 cells in a dose-dependent manner, and had the most prominent effect at 100 nM. Significant increases in the expression of TrkA receptor, ERK1/2 and CREB were observed in ILA-treated PC12 cells, suggesting ILA potentiated NGF-induced neurite outgrowth through the Ras/ERK pathway. Additionally, ILA was found to act as the aryl hydrocarbon receptor (AhR) agonist and evoked NGF-induced neurite outgrowth in an AhR-mediated manner. These new findings provide clues into the potential involvement of ILA as the mediator in bifidobacterial host–microbiota crosstalk and neuronal developmental processes.

scholarly journals Structure of the Repulsive Guidance Molecule (RGM)–Neogenin Signaling Hub

Science ◽  
2013 ◽  
Vol 341 (6141) ◽  
pp. 77-80 ◽  
Author(s):  
Christian H. Bell ◽  
Eleanor Healey ◽  
Susan van Erp ◽  
Benjamin Bishop ◽  
Chenxiang Tang ◽  
...  
Keyword(s):  
Immune Cell ◽  
Cell Surface Receptor ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Autocatalytic Cleavage ◽  
Unknown Protein ◽  
Surface Receptor ◽  
Repulsive Guidance Molecule ◽  
Guidance Molecule ◽  
Multiple Signaling

Repulsive guidance molecule family members (RGMs) control fundamental and diverse cellular processes, including motility and adhesion, immune cell regulation, and systemic iron metabolism. However, it is not known how RGMs initiate signaling through their common cell-surface receptor, neogenin (NEO1). Here, we present crystal structures of the NEO1 RGM-binding region and its complex with human RGMB (also called dragon). The RGMB structure reveals a previously unknown protein fold and a functionally important autocatalytic cleavage mechanism and provides a framework to explain numerous disease-linked mutations in RGMs. In the complex, two RGMB ectodomains conformationally stabilize the juxtamembrane regions of two NEO1 receptors in a pH-dependent manner. We demonstrate that all RGM-NEO1 complexes share this architecture, which therefore represents the core of multiple signaling pathways.

scholarly journals C9orf72-associated arginine-rich dipeptide repeats induce RNA-dependent nuclear accumulation of Staufen in neurons

2021 ◽  
Author(s):  
Eun Seon Kim ◽  
Chang Geon Chung ◽  
Jeong Hyang Park ◽  
Byung Su Ko ◽  
Sung Soon Park ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Nuclear Accumulation ◽  
Heterozygous Mutation ◽  
Pathological Feature ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Drosophila Model ◽  
Post Transcriptional Regulation

Abstract RNA-binding proteins (RBPs) play essential roles in diverse cellular processes through post-transcriptional regulation of RNAs. The subcellular localization of RBPs is thus under tight control, the breakdown of which is associated with aberrant cytoplasmic accumulation of nuclear RBPs such as TDP-43 and FUS, well-known pathological markers for amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD). Here, we report in Drosophila model for ALS/FTD that nuclear accumulation of a cytoplasmic RBP, Staufen, may be a new pathological feature. We found that in Drosophila C4da neurons expressing PR36, one of the arginine-rich dipeptide repeat proteins (DPRs), Staufen accumulated in the nucleus in Importin- and RNA-dependent manner. Notably, expressing Staufen with exogenous NLS—but not with mutated endogenous NLS—potentiated PR-induced dendritic defect, suggesting that nuclear-accumulated Staufen can enhance PR toxicity. PR36 expression increased Fibrillarin staining in the nucleolus, which was enhanced by heterozygous mutation of stau (stau+/−), a gene that codes Staufen. Furthermore, knockdown of fib, which codes Fibrillarin, exacerbated retinal degeneration mediated by PR toxicity, suggesting that increased amount of Fibrillarin by stau+/− is protective. Stau+/− also reduced the amount of PR-induced nuclear-accumulated Staufen and mitigated retinal degeneration and rescued viability of flies expressing PR36. Taken together, our data show that nuclear accumulation of Staufen in neurons may be an important pathological feature contributing to the pathogenesis of ALS/FTD.

scholarly journals On the Need to Tell Apart Fraternal Twins eEF1A1 and eEF1A2, and Their Respective Outfits

2021 ◽  
Vol 22 (13) ◽  
pp. 6973
Author(s):  
Alberto Mills ◽  
Federico Gago
Keyword(s):  
De Novo ◽  
Elongation Factor ◽  
Missense Mutations ◽  
Developmentally Regulated ◽  
High Sequence Identity ◽  
80S Ribosome ◽  
Cellular Effects ◽  
Cellular Processes ◽  
Eukaryotic Elongation Factor ◽  
A Site

eEF1A1 and eEF1A2 are paralogous proteins whose presence in most normal eukaryotic cells is mutually exclusive and developmentally regulated. Often described in the scientific literature under the collective name eEF1A, which stands for eukaryotic elongation factor 1A, their best known activity (in a monomeric, GTP-bound conformation) is to bind aminoacyl-tRNAs and deliver them to the A-site of the 80S ribosome. However, both eEF1A1 and eEF1A2 are endowed with multitasking abilities (sometimes performed by homo- and heterodimers) and can be located in different subcellular compartments, from the plasma membrane to the nucleus. Given the high sequence identity of these two sister proteins and the large number of post-translational modifications they can undergo, we are often confronted with the dilemma of discerning which is the particular proteoform that is actually responsible for the ascribed biochemical or cellular effects. We argue in this review that acquiring this knowledge is essential to help clarify, in molecular and structural terms, the mechanistic involvement of these two ancestral and abundant G proteins in a variety of fundamental cellular processes other than translation elongation. Of particular importance for this special issue is the fact that several de novo heterozygous missense mutations in the human EEF1A2 gene are associated with a subset of rare but severe neurological syndromes and cardiomyopathies.

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