scholarly journals Intracellular Ca2+ Increases and Connexin 43 Hemichannel Opening Are Necessary but Not Sufficient for Thy-1-Induced Astrocyte Migration

2018 ◽  
Vol 19 (8) ◽  
pp. 2179 ◽  
Author(s):  
Raúl Lagos-Cabré ◽  
Marianne Brenet ◽  
Jorge Díaz ◽  
Ramón Pérez ◽  
Leonardo Pérez ◽  
...  
Keyword(s):  
Connexin 43 ◽  
Reactive Astrocytes ◽  
Αvβ3 Integrin ◽  
Neuronal Protein ◽  
Inflammatory Conditions ◽  
Β3 Integrin ◽  
Pre Treatment ◽  
And Migration ◽  
Necrosis Factor ◽  
Migratory Phenotype

Under pro-inflammatory conditions, astrocytes become reactive and acquire a migratory phenotype. Our results show that hemichannels formed by connexin 43 (Cx43) play an important role in Thy-1-induced astrocyte migration. The neuronal protein Thy-1 binds to αvβ3 integrin in astrocytes, thereby leading to intricate signaling pathways that include calcium (Ca2+) release from intracellular stores, opening of Cx43 hemichannels, release of ATP, activation of P2X7 receptor, and Ca2+ influx. However, because these Thy-1 effects occur exclusively in reactive astrocytes, we wondered whether by elevating calcium levels and promoting hemichannel opening we could prompt non-reactive astrocytes to respond to Thy-1. Cx43 immunoreactivity increased at juxta-membrane sites, where hemichannels (not gap junctions) participate in astrocyte polarization and migration stimulated by Thy-1. Also, intracellular Ca2+ increase, due to ionomycin treatment, induced hemichannel opening, but activated astrocyte migration only partially, and this limitation was overcome by pre-treatment with tumor necrosis factor (TNF) and Thy-1. Finally, αvβ3 integrin formed membrane clusters after TNF stimulation or overexpression of β3 integrin. We suggest that these microclusters are required for cells to respond to Thy-1 stimulation. Therefore, the large increase in intracellular Ca2+ and hemichannel opening induced by ionomycin are required, but not sufficient, to permit Thy-1-induced astrocyte migration. Thus, we suggest that proinflammatory stimuli prompt astrocytes to respond to migratory signals of neuronal cells.

Mechanisms and implications of phosphoinositide 3-kinase δ in promoting neutrophil trafficking into inflamed tissue

Blood ◽  
2004 ◽  
Vol 103 (9) ◽  
pp. 3448-3456 ◽  
Author(s):  
Kamal D. Puri ◽  
Teresa A. Doggett ◽  
Jason Douangpanya ◽  
Yonghao Hou ◽  
William T. Tino ◽  
...  
Keyword(s):  
Cell Attachment ◽  
Catalytic Subunit ◽  
Akt Phosphorylation ◽  
Inflammatory Conditions ◽  
Migration Assays ◽  
And Migration ◽  
Phosphoinositide 3 Kinase ◽  
Factor Α ◽  
Necrosis Factor

Abstract The phosphoinositide 3-kinase (PI3K) catalytic subunit p110δ is expressed in neutrophils and is thought to play a role in their accumulation at sites of inflammation by contributing to chemoattractant-directed migration. We report here that p110δ is present in endothelial cells and participates in neutrophil trafficking by modulating the proadhesive state of these cells in response to tumor necrosis factor α (TNFα). Specifically, administration of the selective inhibitor of PI3Kδ, IC87114, to animals reduced neutrophil tethering to and increased rolling velocities on cytokine-activated microvessels in a manner similar to that observed in mice deficient in p110δ. These results were confirmed in vitro as inhibition of this isoform in endothelium, but not neutrophils, diminished cell attachment in flow. A role for PI3Kδ in TNFα-induced signaling is demonstrated by a reduction in Akt-phosphorylation and phosphatidylinositol-dependent kinase 1 (PDK1) enzyme activity upon treatment of this cell type with IC87114. p110δ expressed in neutrophils also contributes to trafficking as demonstrated by the impaired movement of these cells across inflamed venules in animals in which this catalytic subunit was blocked or genetically deleted, results corroborated in transwell migration assays. Thus, PI3Kδ may be a reasonable therapeutic target in specific inflammatory conditions as blockade of its activity reduces neutrophil influx into tissues by diminishing their attachment to and migration across vascular endothelium. (Blood. 2004;103:3448-3456)

scholarly journals αvβ3 integrin spatially regulates VASP and RIAM to control adhesion dynamics and migration

2010 ◽  
Vol 189 (2) ◽  
pp. 369-383 ◽  
Author(s):  
Daniel C. Worth ◽  
Kairbaan Hodivala-Dilke ◽  
Stephen D. Robinson ◽  
Samantha J. King ◽  
Penny E. Morton ◽  
...  
Keyword(s):  
Regulatory Protein ◽  
Focal Adhesions ◽  
Αvβ3 Integrin ◽  
Β1 Integrin ◽  
Downstream Signaling ◽  
Β3 Integrin ◽  
And Migration ◽  
2D And 3D

Integrins are fundamental to the control of protrusion and motility in adherent cells. However, the mechanisms by which specific members of this receptor family cooperate in signaling to cytoskeletal and adhesion dynamics are poorly understood. Here, we show that the loss of β3 integrin in fibroblasts results in enhanced focal adhesion turnover and migration speed but impaired directional motility on both 2D and 3D matrices. These motility defects are coupled with an increased rate of actin-based protrusion. Analysis of downstream signaling events reveals that loss of β3 integrin results in a loss of protein kinase A–dependent phosphorylation of the actin regulatory protein vasodilator-stimulated phosphoprotein (VASP). Dephosphorylated VASP in β3-null cells is preferentially associated with Rap1-GTP–interacting adaptor molecule (RIAM) both in vitro and in vivo, which leads to enhanced formation of a VASP–RIAM complex at focal adhesions and subsequent increased binding of talin to β1 integrin. These data demonstrate a novel mechanism by which αvβ3 integrin acts to locally suppress β1 integrin activation and regulate protrusion, adhesion dynamics, and persistent migration.

Role of α5β1 and αvβ3 Integrins on Smooth Muscle Cell Spreading and Migration in Fibrin Gels

2000 ◽  
Vol 84 (10) ◽  
pp. 701-705 ◽  
Author(s):  
Karen Yee ◽  
Stephen Schwartz ◽  
Yuji Ikari
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Cell Spreading ◽  
Αvβ3 Integrin ◽  
Fibrin Gels ◽  
Αvβ3 Integrins ◽  
Β3 Integrin ◽  
Simultaneous Use ◽  
And Migration

SummaryFibrin is found at sites of vascular injury and is one of the major matrix ligands for β3 integrins. Blocking the β3 integrin on smooth muscle cell is hypothesized as a potential target to prevent restenosis because it could inhibit cell attachment and migration into fibrin provisional matrix. Human aortic smooth muscle cells (HNB18E6E7) spread stably in plasma gels within 24 h. Cell spreading was dramatically blocked by simultaneous use of α5β1 and αvβ3 integrin antibodies (P <0.0001), however, blocking of either integrin alone failed to inhibit spreading. GPenGRGDSPCA, which has been considered a specific αvβ3 antagonist, inhibited spreading at 500 µM, suggesting that the peptide blocked both α5β1 and αvβ3. Similarly, invasive migration into fibrin gels was blocked by simultaneous use of both α5β1 and αvβ3 antibodies, however, blocking of either integrin alone failed to effect cell migration. Another migration assay using transwell indicated similar results. In conclusion, both α5β1 and αvβ3 integrins are responsible for smooth muscle cell spreading and migration into fibrin gels. These data suggest that blocking β3 integrin alone would not affect smooth muscle cell interaction with fibrin.

scholarly journals Cyr61 promotes Schwann cell proliferation and migration via αvβ3 integrin

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhenghui Cheng ◽  
Yawen Zhang ◽  
Yinchao Tian ◽  
Yuhan Chen ◽  
Fei Ding ◽  
...  
Keyword(s):  
Nerve Injury ◽  
Peripheral Nerves ◽  
Molecular Mechanisms ◽  
Αvβ3 Integrin ◽  
Promoting Effect ◽  
Ccn Family ◽  
And Migration ◽  
Proliferation And Migration

Abstract Background Schwann cells (SCs) play a crucial role in the repair of peripheral nerves. This is due to their ability to proliferate, migrate, and provide trophic support to axon regrowth. During peripheral nerve injury, SCs de-differentiate and reprogram to gain the ability to repair nerves. Cysteine-rich 61 (Cyr61/CCN1) is a member of the CCN family of matrix cell proteins and have been reported to be abundant in the secretome of repair mediating SCs. In this study we investigate the function of Cyr61 in SCs. Results We observed Cyr61 was expressed both in vivo and in vitro. The promoting effect of Cyr61 on SC proliferation and migration was through autocrine and paracrine mechanisms. SCs expressed αvβ3 integrin and the effect of Cyr61 on SC proliferation and migration could be blocked via αvβ3 integrin. Cyr61 could influence c-Jun protein expression in cultured SCs. Conclusions In this study, we found that Cyr61 promotes SC proliferation and migration via αvβ3 integrin and regulates c-Jun expression. Our study contributes to the understanding of cellular and molecular mechanisms underlying SC’s function during nerve injury, and thus, may facilitate the regeneration of peripheral nerves after injury.

scholarly journals Structural and functional analysis of LIM domain-dependent recruitment of paxillin to αvβ3 integrin-positive focal adhesions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Marta Ripamonti ◽  
Nicolas Liaudet ◽  
Latifeh Azizi ◽  
Daniel Bouvard ◽  
Vesa P. Hytönen ◽  
...  
Keyword(s):  
Focal Adhesions ◽  
Bimolecular Fluorescence Complementation ◽  
Molecular Organization ◽  
Structural Function ◽  
Αvβ3 Integrin ◽  
Lim Domain ◽  
Dissociation Kinetics ◽  
Mechanical Coupling ◽  
Β3 Integrin

AbstractThe LIM domain-dependent localization of the adapter protein paxillin to β3 integrin-positive focal adhesions (FAs) is not mechanistically understood. Here, by combining molecular biology, photoactivation and FA-isolation experiments, we demonstrate specific contributions of each LIM domain of paxillin and reveal multiple paxillin interactions in adhesion-complexes. Mutation of β3 integrin at a putative paxillin binding site (β3VE/YA) leads to rapidly inward-sliding FAs, correlating with actin retrograde flow and enhanced paxillin dissociation kinetics. Induced mechanical coupling of paxillin to β3VE/YA integrin arrests the FA-sliding, thereby disclosing an essential structural function of paxillin for the maturation of β3 integrin/talin clusters. Moreover, bimolecular fluorescence complementation unveils the spatial orientation of the paxillin LIM-array, juxtaposing the positive LIM4 to the plasma membrane and the β3 integrin-tail, while in vitro binding assays point to LIM1 and/or LIM2 interaction with talin-head domain. These data provide structural insights into the molecular organization of β3 integrin-FAs.

scholarly journals Absence of the αvβ3 Integrin Dictates the Time-Course of Angiogenesis in the Hypoxic Central Nervous System: Accelerated Endothelial Proliferation Correlates with Compensatory Increases in α5β1 Integrin Expression

2010 ◽  
Vol 30 (5) ◽  
pp. 1031-1043 ◽  
Author(s):  
Longxuan Li ◽  
Jennifer V Welser ◽  
Richard Milner
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Time Course ◽  
Αvβ3 Integrin ◽  
Integrin Expression ◽  
Brain Endothelial Cells ◽  
Endothelial Proliferation ◽  
Β3 Integrin ◽  
Α5β1 Integrin

Cerebral angiogenesis is an important adaptive response to hypoxia. As the αvβ3 integrin is induced on angiogenic vessels in the ischemic central nervous system (CNS), and the suggested angiogenic role for this integrin in other systems, it is important to determine whether the αvβ3 integrin is an important mediator of cerebral angiogenesis. αvβ3 integrin expression was examined in a model of cerebral hypoxia, in which mice were subject to hypoxia (8% O2) for 0, 4, 7, or 14 days. Immunofluorescence and western blot analysis revealed that in the hypoxic CNS, αvβ3 integrin was strongly induced on angiogenic brain endothelial cells (BEC), along with its ligand vitronectin. In the hypoxia model, β3 integrin-null mice showed no obvious defect in cerebral angiogenesis. However, early in the angiogenic process, BEC in these mice showed an increased mitotic index that correlated closely with increased α5 integrin expression. In vitro experiments confirmed α5 integrin upregulation on β3 integrin-null BEC, which also correlated with increased BEC proliferation on fibronectin. These studies confirm hypoxic induction of αvβ3 integrin on angiogenic vessels, but suggest distinct roles for the BEC integrins αvβ3 and α5β1 in cerebral angiogenesis, with αvβ3 having a nonessential role, and α5β1 promoting BEC proliferation.

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 TNF-α plus IL-1β Induces Opposite Regulation of Hemichannels and Gap Junctions in Mesangial Cells Through a RhoA/ROCK-dependent Pathway

2021 ◽  
Author(s):  
Claudia M. Lucero ◽  
Marcelo A. León ◽  
Paola Fernández ◽  
Juan A. Orellana ◽  
Victoria Velarde ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Connexin 43 ◽  
Mesangial Cells ◽  
Thiobarbituric Acid ◽  
Progressive Increase ◽  
Cell Coupling ◽  
Inflammatory Conditions ◽  
Junctional Communication ◽  
Junctional Coupling ◽  
Gap Junctional

Connexin 43 (Cx43) is expressed in kidneys and constitutes a feedforward mechanism leading to inflammation in other tissues where they form hemichannels and gap junction channels. However, the possible functional relationship between these membrane channels and their role in damaged renal cells remains unknown. Here, analyses of ethidium uptake and thiobarbituric acid reactive species revealed that TNF-&alpha; plus IL-1&beta; increase Cx43 hemichannel activity and oxidative stress in MES-13 cells, a cell line derived from mesangial cells. The latter also was accompanied by a reduction in gap junctional communication, whereas western blotting analysis showed a progressive increase of phosphorylated MYPT (a substrate of RhoA/ROCK) and Cx43 upon TNF-&alpha;/IL-1&beta; treatment. Additionally, inhibition of RhoA/ROCK strongly diminished the TNF-&alpha;/IL-1&beta;-induced activation of Cx43 hemichannels and reduction in gap junctional coupling. We propose that activation of Cx43 hemichannels and inhibition of cell coupling during pro-inflammatory conditions could contribute to oxidative stress and damage of mesangial cells via the RhoA/ROCK pathway.

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