scholarly journals HIV gp120 Protein Increases the Function of Connexin 43 Hemichannels and Pannexin-1 Channels in Astrocytes: Repercussions on Astroglial Function

2020 ◽  
Vol 21 (7) ◽  
pp. 2503 ◽  
Author(s):  
Rosario Gajardo-Gómez ◽  
Cristian A. Santibañez ◽  
Valeria C. Labra ◽  
Gonzalo I. Gómez ◽  
Eliseo A. Eugenin ◽  
...  
Keyword(s):  
Connexin 43 ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Purinergic Signaling ◽  
Atp Release ◽  
P38 Map Kinase ◽  
Motor Deficits ◽  
Pannexin 1 ◽  
Channel Opening ◽  
Wide Range

At least half of human immunodeficiency virus (HIV)-infected individuals suffer from a wide range of cognitive, behavioral and motor deficits, collectively known as HIV-associated neurocognitive disorders (HAND). The molecular mechanisms that amplify damage within the brain of HIV-infected individuals are unknown. Recently, we described that HIV augments the opening of connexin-43 (Cx43) hemichannels in cultured human astrocytes, which result in the collapse of neuronal processes. Whether HIV soluble viral proteins such as gp120, can regulate hemichannel opening in astrocytes is still ignored. These channels communicate the cytosol with the extracellular space during pathological conditions. We found that gp120 enhances the function of both Cx43 hemichannels and pannexin-1 channels in mouse cortical astrocytes. These effects depended on the activation of IL-1β/TNF-α, p38 MAP kinase, iNOS, cytoplasmic Ca2+ and purinergic signaling. The gp120-induced channel opening resulted in alterations in Ca2+ dynamics, nitric oxide production and ATP release. Although the channel opening evoked by gp120 in astrocytes was reproduced in ex vivo brain preparations, these responses were heterogeneous depending on the CA1 region analyzed. We speculate that soluble gp120-induced activation of astroglial Cx43 hemichannels and pannexin-1 channels could be crucial for the pathogenesis of HAND.

A dual voltage clamp technique to study gap junction hemichannels in astrocytes cultured from neonatal rodent spinal cords

2021 ◽  
Author(s):  
Juan Mauricio Garre ◽  
Feliksas F Bukauskas ◽  
Michael V Bennett
Keyword(s):  
Voltage Clamp ◽  
Connexin 43 ◽  
Single Channel ◽  
Purinergic Signaling ◽  
Atp Release ◽  
Single Channels ◽  
P2x7 Receptors ◽  
Voltage Clamp Technique ◽  
Pannexin 1 ◽  
Clamp Technique

Astrocytes express surface channels involved in purinergic signaling, and among these channels, pannexin-1 (Px1) and connexin-43 (Cx43) hemichannels (HCs) mediate ATP release that acts directly, or through its derivatives, on neurons and glia via purinergic receptors. Although HCs are functional, i.e., open and close, under physiological and pathological conditions, single channel conductance of Px1 HCs is not well defined. Here, we developed a dual voltage clamp technique in HeLa cells overexpressing human Px1-YFP, and then applied this system to rodent spinal astrocytes. Single channels were recorded in cell attached patches and evoked with ramp cycles of 2 s duration and -/+ 80-100 mV amplitude or rectangular pulses through another pipette in whole cell clamp. Conductance of Px1 HC openings recorded during ramp stimuli ranged 25-110 pS. Based on their single channel conductances, Px1 HCs could be distinguished from Cx43 HCs and P2X7 receptors (P2X7Rs) in spinal astrocytes during dual voltage clamp experiments. Furthermore, we found that single channel activity of Cx43 HCs and P2X7Rs was increased, and that of Px1 HCs was decreased, in spinal astrocytes treated for 7h with FGF-1, a growth factor implicated in neurodevelopment, repair and inflammation.

A2A Receptor-induced Overexpression of Pannexin-1 Hemichannels Indirectly Mediates Adenosine Fibrogenic Actions in Subcutaneous Human Fibroblasts by Favoring ATP Release

2021 ◽  
Author(s):  
Carina Herman-de-Sousa ◽  
Maria Adelina Costa ◽  
Rafaela Pedro Silva ◽  
Fátima Ferreirinha ◽  
Severino Ribeiro ◽  
...  
Keyword(s):  
Inflammatory Mediators ◽  
Connexin 43 ◽  
Myofascial Pain ◽  
Subcutaneous Tissue ◽  
Human Fibroblasts ◽  
Atp Release ◽  
Collagen Production ◽  
Pannexin 1 ◽  
A2a Receptors ◽  
Inflammatory Conditions

Abstract Disorganization of the subcutaneous tissue due to inflammation and fibrosis is a common feature in patients with myofascial pain. Dermal accumulation of adenosine favours collagen production by human subcutaneous fibroblasts (HSCF) via A2A receptors (A2AR) activation. Adenosine mimics the fibrogenic effect of inflammatory mediators (e.g. histamine, bradykinin), which act by promoting ATP release from HSCF via pannexin-1 (Panx1) and/or connexin-43 (Cx43) hemichannels. However, this mechanism was never implicated in the A2AR-mediated actions. NECA and CGS21680C, two enzymatically-stable A2AR agonists, increased Panx-1, but reduced Cx43, immunoreactivity in cultured HSCF. This effect was accompanied by increases in ATP release and collagen production by HSCF. Involvement of A2AR was verified upon blockage of NECA and CGS21680 effects with the selective A2AR antagonist, SCH442416. Inhibition of Panx1 hemichannels with probenecid also decreased ATP release and collagen production by HSCF under similar conditions. Superfluous ATP release by HSCF exposed to A2AR agonists overexpressing Panx1 hemichannels contributes to keep high [Ca2+]i levels in the presence of inflammatory mediators, like histamine. Adenosine A2AR-induced Panx1 overexpression was shown here for the first time; this feature indirectly implicates ATP release in the fibrogenic vicious cycle putatively operated by the nucleoside in subcutaneous tissue fibrosis and myofascial inflammatory conditions.

scholarly journals Structure versus function: Are new conformations of pannexin 1 yet to be resolved?

2021 ◽  
Vol 153 (5) ◽  
Author(s):  
Carsten Mim ◽  
Guy Perkins ◽  
Gerhard Dahl
Keyword(s):  
Structural Information ◽  
Purinergic Signaling ◽  
Atp Release ◽  
Strong Support ◽  
Decisive Role ◽  
Chloride Ions ◽  
Pannexin 1 ◽  
Selective Membrane ◽  
Selective Channel ◽  
Structure Versus

Pannexin 1 (Panx1) plays a decisive role in multiple physiological and pathological settings, including oxygen delivery to tissues, mucociliary clearance in airways, sepsis, neuropathic pain, and epilepsy. It is widely accepted that Panx1 exerts its role in the context of purinergic signaling by providing a transmembrane pathway for ATP. However, under certain conditions, Panx1 can also act as a highly selective membrane channel for chloride ions without ATP permeability. A recent flurry of publications has provided structural information about the Panx1 channel. However, while these structures are consistent with a chloride selective channel, none show a conformation with strong support for the ATP release function of Panx1. In this Viewpoint, we critically assess the existing evidence for the function and structure of the Panx1 channel and conclude that the structure corresponding to the ATP permeation pathway is yet to be determined. We also list a set of additional topics needing attention and propose ways to attain the large-pore, ATP-permeable conformation of the Panx1 channel.

scholarly journals Pannexin-1 mediated ATP release in adipocytes is sensitive to glucose and insulin and modulates lipolysis and macrophage migration

2018 ◽  
Author(s):  
Marco Tozzi ◽  
Jacob B. Hansen ◽  
Ivana Novak
Keyword(s):  
Adipose Tissue ◽  
Purinergic Receptors ◽  
Purinergic Signaling ◽  
Cell Metabolism ◽  
Atp Release ◽  
Extracellular Atp ◽  
Adrenergic Stimulation ◽  
Pannexin 1 ◽  
White Adipocytes ◽  
Obesity And Diabetes

One-sentence summaryInsulin inhibits ATP release in adipocytesAbstractExtracellular ATP signaling is involved in many physiological and pathophysiological processes, and purinergic receptors are targets for drug therapy in several diseases, including obesity and diabetes. Adipose tissue has crucial functions in lipid and glucose metabolism and adipocytes express purinergic receptors. However, the sources of extracellular ATP in adipose tissue are not yet characterized.Here, we show that upon adrenergic stimulation white adipocytes release ATP through the pannexin-1 pore that is regulated by a cAMP-PKA dependent pathway. The ATP release correlates with increased cell metabolism, and extracellular ATP induces Ca2+ signaling and lipolysis in adipocytes and promotes macrophages migration. Most importantly, ATP release is markedly inhibited by insulin, and thereby auto/paracrine purinergic signaling in adipose tissue would be attenuated. Furthermore, we define the signaling pathway for insulin regulated ATP release.Our findings reveal the insulin-pannexin-1-purinergic signaling cross-talk in adipose tissue and we propose that deregulation of this signaling may underlie adipose tissue inflammation and type-2 diabetes.

scholarly journals The Involvement of PPARγ In Anti-Inflammatory Activity of N-Stearoylethanolamide

2021 ◽  
Author(s):  
Halyna Kosiakova ◽  
Andrii Berdyshev ◽  
Victor Dosenko ◽  
Tetyana Drevytska ◽  
Oleksandra Herasymenko ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Methodological Approach ◽  
Mrna Level ◽  
Peritoneal Macrophages ◽  
Insulin Resistant ◽  
Wide Range ◽  
Anti Inflammatory ◽  
Pre Treatment ◽  
Inflammatory Action

Abstract N-stearoylethanolamide (NSE)– a cannabinoid-like compound with wide range of biological activity. Anti-inflammatory properties of NSE have been indicated on different animal models of pathological conditions. However, the molecular mechanisms of anti-inflammatory action of NSE remain unclear. In the current study, the involvement of PPARγ in the NF-kB -dependent anti-inflammatory action of NSE was evaluated using different methodological approach. First method - molecular modeling, evaluated the possibility of NSE to bind with PPAR. Then, in ex vivo experiment, using selective synthetic agonist of PPARα/γ LY-171883 and selective antagonist of PPARγ - GW9662, the role of PPARα /PPARγ in the NSE’s effect on nuclear NF-kB translocation was examined in LPS-activated rat peritoneal macrophages. Finally, the NSE action on the mRNA level of several PPARγ- dependent genes was studied in liver of insulin-resistant rats. The molecular docking results showed that NSE could bind to PPARγ and compete for the binding with antagonist GW9662 and agonist LY171883 in the active site of PPARγ. It also has been found that NSE prevented the LPS-induced NF-kB translocation into the nuclei of rat peritoneal macrophages during pre-treatment with NSE before LPS application. When NSE was added before GW9662 and LPS treatment, the level of NF-kB translocation and IL-1β content reduced to control cells’ levels. These data confirmed a competitive binding of NSE with GW9662 for the ligand-binding domen of PPARγ. In addition, NSE administration to insulin resistant rats changed the mRNA expression of several PPARγ target gens, including FATP1 and IL1-ra.

scholarly journals Astragaloside IV Attenuates Myocardial Ischemia-Reperfusion Injury from Oxidative Stress by Regulating Succinate, Lysophospholipid Metabolism, and ROS Scavenging System

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Miaomiao Jiang ◽  
Jingyu Ni ◽  
Yuanlin Cao ◽  
Xiaoxue Xing ◽  
Qian Wu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Molecular Mechanisms ◽  
Ischemia Reperfusion Injury ◽  
Ex Vivo ◽  
Ischemia Reperfusion ◽  
Ros Generation ◽  
Heme Oxygenase 1 ◽  
Ros Scavenging ◽  
Astragaloside Iv ◽  
Wide Range

Astragaloside IV is one of the main active ingredients isolated from Astragalus membranaceus. Here we confirmed its protective effect against cardiac ischemia-reperfusion (I/R) injury and aimed to investigate the potential molecular mechanisms involved. Pretreatment of ex vivo and in vivo I/R-induced rat models by astragaloside IV significantly prevented the ratio of myocardium infarct size, systolic and diastolic dysfunction, and the production of creatine kinase and lactate dehydrogenase. Metabolic analyses showed that I/R injury caused a notable reduction of succinate and elevation of lysophospholipids, indicating excessive reactive oxygen species (ROS) generation driven by succinate’s rapid reoxidization and glycerophospholipid degradation. Molecular validation mechanistically revealed that astragaloside IV stimulated nuclear factor (erythroid-derived 2)-like 2 (Nrf2) released from Kelch-like ECH-associated protein 1 (Keap1) and translocated to the nucleus to combine with musculoaponeurotic fibrosarcoma (Maf) to initiate the transcription of antioxidative gene heme oxygenase-1 (HO-1), which performed a wide range of ROS scavenging processes against pathological oxidative stress in the hearts. As expected, increasing succinate and decreasing lysophospholipid levels were observed in the astragaloside IV-pretreated group compared with the I/R model group. These results suggested that astragaloside IV ameliorated myocardial I/R injury by modulating succinate and lysophospholipid metabolism and scavenging ROS via the Nrf2 signal pathway.

scholarly journals Inhibition of Pannexin 1 Reduces the Tumorigenic Properties of Human Melanoma Cells

Cancers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 102 ◽  
Author(s):  
Taylor Freeman ◽  
Samar Sayedyahossein ◽  
Danielle Johnston ◽  
Rafael Sanchez-Pupo ◽  
Brooke O’Donnell ◽  
...  
Keyword(s):  
Cell Lines ◽  
Purinergic Signaling ◽  
Atp Release ◽  
Melanoma Cells ◽  
Human Melanoma ◽  
Channel Blockers ◽  
Melanoma Tumor ◽  
Cell Growth And Migration ◽  
Pannexin 1 ◽  
Protein Levels

Pannexin 1 (PANX1) is a channel-forming glycoprotein expressed in many tissues including the skin. PANX1 channels allow the passage of ions and molecules up to 1 kDa, including ATP and other metabolites. In this study, we show that PANX1 is highly expressed in human melanoma tumors at all stages of disease progression, as well as in patient-derived cells and established melanoma cell lines. Reducing PANX1 protein levels using shRNA or inhibiting channel function with the channel blockers, carbenoxolone (CBX) and probenecid (PBN), significantly decreased cell growth and migration, and increased melanin production in A375-P and A375-MA2 cell lines. Further, treatment of A375-MA2 tumors in chicken embryo xenografts with CBX or PBN significantly reduced melanoma tumor weight and invasiveness. Blocking PANX1 channels with PBN reduced ATP release in A375-P cells, suggesting a potential role for PANX1 in purinergic signaling of melanoma cells. In addition, cell-surface biotinylation assays indicate that there is an intracellular pool of PANX1 in melanoma cells. PANX1 likely modulates signaling through the Wnt/β-catenin pathway, because β-catenin levels were significantly decreased upon PANX1 silencing. Collectively, our findings identify a role for PANX1 in controlling growth and tumorigenic properties of melanoma cells contributing to signaling pathways that modulate melanoma progression.

scholarly journals Hematopoietic Differentiation of Human Pluripotent Stem Cells: HOX and GATA Transcription Factors as Master Regulators

2019 ◽  
Vol 20 (6) ◽  
pp. 438-452 ◽  
Author(s):  
Khaled Alsayegh ◽  
Lorena V. Cortés-Medina ◽  
Gerardo Ramos-Mandujano ◽  
Heba Badraiq ◽  
Mo Li
Keyword(s):  
Stem Cells ◽  
Transcription Factors ◽  
Pluripotent Stem Cells ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
The Body ◽  
Hematopoietic Differentiation ◽  
Hematopoietic Stem ◽  
Master Regulators ◽  
Wide Range

Numerous human disorders of the blood system would directly or indirectly benefit from therapeutic approaches that reconstitute the hematopoietic system. Hematopoietic stem cells (HSCs), either from matched donors or ex vivo manipulated autologous tissues, are the most used cellular source of cell therapy for a wide range of disorders. Due to the scarcity of matched donors and the difficulty of ex vivo expansion of HSCs, there is a growing interest in harnessing the potential of pluripotent stem cells (PSCs) as a de novo source of HSCs. PSCs make an ideal source of cells for regenerative medicine in general and for treating blood disorders in particular because they could expand indefinitely in culture and differentiate to any cell type in the body. However, advancement in deriving functional HSCs from PSCs has been slow. This is partly due to an incomplete understanding of the molecular mechanisms underlying normal hematopoiesis. In this review, we discuss the latest efforts to generate human PSC (hPSC)-derived HSCs capable of long-term engraftment. We review the regulation of the key transcription factors (TFs) in hematopoiesis and hematopoietic differentiation, the Homeobox (HOX) and GATA genes, and the interplay between them and microRNAs. We also propose that precise control of these master regulators during the course of hematopoietic differentiation is key to achieving functional hPSC-derived HSCs.

scholarly journals Endothelial pannexin 1 channels control inflammation by regulating intracellular calcium

2019 ◽  
Author(s):  
Yang Yang ◽  
Leon Delalio ◽  
Angela K Best ◽  
Edgar Macal ◽  
Jenna Milstein ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Endothelial Cells ◽  
Plasma Membrane ◽  
Intracellular Calcium ◽  
Tumor Necrosis ◽  
Purinergic Signaling ◽  
Flow Cytometric Analysis ◽  
Atp Release ◽  
Pannexin 1 ◽  
Intracellular Ca

In BriefInterleukine-1 beta (IL-1β) has been identified as a critical factor that contributes to the inflammatory response in cardiovascular disease (e.g., atherosclerosis). Pannexin 1 (Panx1) channel activity in endothelial cells regulates localized inflammatory cell recruitment. In response to prolonged tumor necrosis factor alpha (TNF) treatment, Yang et al. found that the Panx1 channel is targeted to the plasma membrane, where it facilitates an increase in intracellular calcium to control the production and release of cytokines including IL-1β.GRAPHICAL ABSTRACTAbstractThe proinflammatory cytokine IL-1β is a significant risk factor in cardiovascular disease that can be targeted to reduce major cardiovascular events. IL-1β expression and release are tightly controlled by changes in intracellular Ca2+. In addition, purinergic signaling through ATP release has also been reported to promote IL-1β production. Despite this, the mechanisms that control IL-1β synthesis and expression have not been identified. The pannexin 1 (Panx1) channel has canonically been implicated in ATP release, especially during inflammation. However, resolution of purinergic signaling occurs quickly due to blood flow and the presence of ectonucleotidases. We examined Panx1 in human endothelial cells following treatment with the pro-inflammatory cytokine tumor necrosis alpha (TNF). In response to long-term TNF treatment, we identified a dramatic increase in Panx1 protein expression at the plasma membrane. Analysis by whole transcriptome sequencing (RNA-seq), qPCR, and treatment with specific kinase inhibitors, revealed that TNF signaling induced NFκβ-associated Panx1 transcription. Genetic inhibition of Panx1 reduced the expression and secretion of IL-1β. We initially hypothesized that increased Panx1-mediated ATP release acted in a paracrine fashion to control cytokine expression. However, our data demonstrate that IL1-β expression was not altered after direct ATP stimulation, following degradation of ATP by apyrase, or after pharmacological blockade of P2 receptors. These data suggest that non-purinergic pathways, involving Panx1, control IL-1β production. Because Panx1 forms a large pore channel, we hypothesized it may act to passively diffuse Ca2+ into the cell upon opening to regulate IL-1β. High-throughput flow cytometric analysis demonstrated that TNF treatments lead to elevated intracellular Ca2+. Genetic or pharmacological inhibition of Panx1 reduced TNF-associated increases in intracellular Ca2+, and IL-1β transcription. Furthermore, we found that the Ca2+-sensitive NFκβ-p65 protein failed to localize to the nucleus after genetic or pharmacological block of Panx1. Taken together, our study provides the first evidence that intracellular Ca2+ regulation via the Panx1 channel induces a feed-forward effect on NFκβ to regulate IL-1β synthesis and release in endothelium during inflammation.

scholarly journals P11.29 Development of ex vivo models for deeper insights into the biology and therapeutic targeting of tumor microtube networks in gliomas

2019 ◽  
Vol 21 (Supplement_3) ◽  
pp. iii49-iii49
Author(s):  
E Jung ◽  
D Domínguez Azorín ◽  
D Hausmann ◽  
M Mall ◽  
P Koch ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Connexin 43 ◽  
Laser Scanning ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Therapy Resistance ◽  
Laser Scanning Microscopy ◽  
Live Cells ◽  
Fluorescent Reporter ◽  
Cell Networks

Abstract BACKGROUND The formation of multicellular networks via thin cellular protrusions named tumor microtubes (TMs) emerged as a novel mechanism of therapy resistance in malignant glioma. TMs are also involved in tumor cell invasion and growth. Within these tumor cell networks, connected tumor cells communicate via intercellular calcium waves (ICWs). Only few molecular drivers of TMs (Gap43, Ttyh1, Connexin 43) have been identified until now. Furthermore, the molecular mechanisms underlying ICWs as well as their specific biological role in glioma remains to be elucidated. A better understanding of the biology and the identification of molecular key drivers is essential for the development of drugs targeting TM formation and function. MATERIAL AND METHODS For this purpose, we have developed novel ex vivo models that not only provide insights into TM biology but further allow medium throughput drug screening. As classical response parameters such as the inhibition of cell growth or cytotoxicity do not necessarily correlate with effects on TM formation or function, a morphometrical approach employing laser scanning microscopy and machine-learning based image analysis tools is used. The application of fluorescent probes and genetic fluorescent reporter systems provides novel longitudinal insights into cytoskeletal dynamics, the role and exchange of organelles such as mitochondria, mechanisms of homeostasis within tumor cell networks (e.g. redox homeostasis) and ICWs in live cells. In addition to 2D glioma cell and co-culture models we have developed a fully human and mature brain organoid model. Here, complex 3D tumor cell networks corresponding to the morphology and exhibiting calcium communication patterns observed in our mouse model can be established and studied ex vivo. Furthermore, with these models not only the role of the brain microenvironment on TM formation but also direct interactions of glioma cells with neurons and glial cells as well as drug effects such as cytotoxicity on these brain cells can be investigated ex vivo. CONCLUSION In summary, novel tumor models enable further insights into TM biology and hence provide the basis for development of TM- and network disrupting drugs. First results of this screening opportunity will be presented.

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