scholarly journals Protein kinase G signaling disrupts Rac1-dependent focal adhesion assembly in liver specific pericytes

2011 ◽  
Vol 301 (1) ◽  
pp. C66-C74 ◽  
Author(s):  
Chittaranjan Routray ◽  
Chunsheng Liu ◽  
Usman Yaqoob ◽  
Daniel D. Billadeau ◽  
Kenneth D. Bloch ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Stellate Cells ◽  
Small Gtpase ◽  
Protein Kinase G ◽  
Effector Protein ◽  
Phosphorylation Sites ◽  
Paracrine Signaling ◽  
Inhibitory Effects ◽  
And Migration ◽  
Fa Markers

Nitric oxide (NO) regulates the function of perivascular cells (pericytes), including hepatic stellate cells (HSC), mainly by activating cGMP and cGMP-dependent kinase (PKG) via NO/cGMP paracrine signaling. Although PKG is implicated in integrin-mediated cell adhesion to extracellular matrix, whether or how PKG signaling regulates the assembly of focal adhesion complexes (FA) and migration of HSC is not known. With the help of complementary molecular and cell biological approaches, we demonstrate here that activation of PKG signaling in HSC inhibits vascular tubulogenesis, migration/chemotaxis, and assembly of mature FA plaques, as assessed by vascular tubulogenesis assays and immunofluorescence localization of FA markers such as vinculin and vasodilator-stimulated phosphoprotein (VASP). To determine whether PKG inhibits FA assembly by phosphorylation of VASP at Ser-157, Ser-239, and Thr-278, we mutated these putative phosphorylation sites to alanine (VASP3A, phosphoresistant mutant) or aspartic acid (VASP3D, phosphomimetic), respectively. Data generated from these two mutants suggest that the effect of PKG on FA is independent of these three phosphorylation sites. In contrast, activation of PKG inhibits the activity of small GTPase Rac1 and its association with the effector protein IQGAP1. Moreover, PKG activation inhibits the formation of a trimeric protein complex containing Rac1, IQGAP1, and VASP. Finally, we found that expression of a constitutively active Rac1 mutant abolishes the inhibitory effects of PKG on FA formation. In summary, our data suggest that activation of PKG signaling in pericytes inhibits FA formation by inhibiting Rac1.

scholarly journals Bivalent Ligand UDCA-LPE Inhibits Pro-Fibrogenic Integrin Signalling by Inducing Lipid Raft-Mediated Internalization

2018 ◽  
Vol 19 (10) ◽  
pp. 3254 ◽  
Author(s):  
Jie Su ◽  
Hongying Gan-Schreier ◽  
Benjamin Goeppert ◽  
Walee Chamulitrat ◽  
Wolfgang Stremmel ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Hepatic Stellate Cells ◽  
Stellate Cells ◽  
Inhibitory Effects ◽  
Integrin Β1 ◽  
Transport Pathway ◽  
Fatty Acid Chain ◽  
Embryonic Liver Cell

Ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE) is a synthetic bile acid-phospholipid conjugate with profound hepatoprotective and anti-fibrogenic functions in vitro and in vivo. Herein, we aimed to demonstrate the inhibitory effects of UDCA-LPE on pro-fibrogenic integrin signalling. UDCA-LPE treatment of human embryonic liver cell line CL48 and primary human hepatic stellate cells induced a non-classical internalization of integrin β1 resulting in dephosphorylation and inhibition of SRC and focal adhesion kinase (FAK). Signalling analyses suggested that UDCA-LPE may act as a heterobivalent ligand for integrins and lysophospholipid receptor1 (LPAR1) and co-immunoprecipitation demonstrated the bridging effect of UDCA-LPE on integrin β1 and LPAR1. The disruption of either the UDCA-moiety binding to integrins by RGD-containing peptide GRGDSP or the LPE-moiety binding to LPAR1 by LPAR1 antagonist Ki16425 reversed inhibitory functions of UDCA-LPE. The lack of inhibitory functions of UDCA-PE and UDCA-LPE derivatives (14:0 and 12:0, LPE-moiety containing shorter fatty acid chain) as well as the consistency of the translocation of UDCA-LPE and integrins, which co-fractionated with LPE but not UDCA, suggested that the observed UDCA-LPE-induced translocation of integrins was mediated by LPE endocytic transport pathway.

scholarly journals Novel and Converging Ways of NOX2 and SOD3 in Trafficking and Redox Signaling in Macrophages

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 172
Author(s):  
Steen Vang Petersen ◽  
Nanna Bach Poulsen ◽  
Cecilie Linneberg Matthiesen ◽  
Frederik Vilhardt
Keyword(s):  
Hydrogen Peroxide ◽  
Membrane Trafficking ◽  
Spatial Organization ◽  
Redox Signaling ◽  
Small Gtpase ◽  
Paracrine Signaling ◽  
Tissue Macrophage ◽  
Storage Vesicles ◽  
Superoxide Dismutase 3 ◽  
Macrophage Populations

Macrophages and related tissue macrophage populations use the classical NADPH oxidase (NOX2) for the regulated production of superoxide and derived oxidants for pathogen combat and redox signaling. With an emphasis on macrophages, we discuss how sorting into secretory storage vesicles, agonist-responsive membrane trafficking, and segregation into sphingolipid and cholesterol-enriched microdomains (lipid rafts) determine the subcellular distribution and spatial organization of NOX2 and superoxide dismutase-3 (SOD3). We discuss how inflammatory activation of macrophages, in part through small GTPase Rab27A/B regulation of the secretory compartments, mediates the coalescence of these two proteins on the cell surface to deliver a focalized hydrogen peroxide output. In interplay with membrane-embedded oxidant transporters and redox sensitive target proteins, this arrangement allows for the autocrine and paracrine signaling, which govern macrophage activation states and transcriptional programs. By discussing examples of autocrine and paracrine redox signaling, we highlight why formation of spatiotemporal microenvironments where produced superoxide is rapidly converted to hydrogen peroxide and conveyed immediately to reach redox targets in proximal vicinity is required for efficient redox signaling. Finally, we discuss the recent discovery of macrophage-derived exosomes as vehicles of NOX2 holoenzyme export to other cells.

scholarly journals Inhibitory effects of Yangzheng Xiaoji on angiogenesis and the role of the focal adhesion kinase pathway

2012 ◽  
Vol 41 (5) ◽  
pp. 1635-1642 ◽  
Author(s):  
WEN G. JIANG ◽  
LIN YE ◽  
KE JI ◽  
NATASHA FREWER ◽  
JIAFU JI ◽  
...  
Keyword(s):  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Inhibitory Effects ◽  
Kinase Pathway

scholarly journals PLCε1 regulates SDF-1α–induced lymphocyte adhesion and migration to sites of inflammation

2017 ◽  
Vol 114 (10) ◽  
pp. 2693-2698 ◽  
Author(s):  
Marianne Strazza ◽  
Inbar Azoulay-Alfaguter ◽  
Michael Peled ◽  
Alan V. Smrcka ◽  
Edward Y. Skolnik ◽  
...  
Keyword(s):  
T Cell ◽  
Small Gtpase ◽  
The Body ◽  
Delayed Type Hypersensitivity ◽  
Intercellular Adhesion Molecule ◽  
Intercellular Adhesion Molecule 1 ◽  
Regional Lymph Nodes ◽  
Lymphocyte Adhesion ◽  
Enzymatic Function ◽  
And Migration

Regulation of integrins is critical for lymphocyte adhesion to endothelium and migration throughout the body. Inside-out signaling to integrins is mediated by the small GTPase Ras-proximate-1 (Rap1). Using an RNA-mediated interference screen, we identified phospholipase Cε 1 (PLCε1) as a crucial regulator of stromal cell-derived factor 1 alpha (SDF-1α)-induced Rap1 activation. We have shown that SDF-1α-induced activation of Rap1 is transient in comparison with the sustained level following cross-linking of the antigen receptor. We identified that PLCε1 was necessary for SDF-1α-induced adhesion using shear stress, cell morphology alterations, and crawling on intercellular adhesion molecule 1 (ICAM-1)–expressing cells. Structure–function experiments to separate the dual-enzymatic function of PLCε1 uncover necessary contributions of the CDC25, Pleckstrin homology, and Ras-associating domains, but not phospholipase activity, to this pathway. In the mouse model of delayed type hypersensitivity, we have shown an essential role for PLCε1 in T-cell migration to inflamed skin, but not for cytokine secretion and proliferation in regional lymph nodes. Our results reveal a signaling pathway where SDF-1α induces T-cell adhesion through activation of PLCε1, suggesting that PLCε1 is a specific potential target in treating conditions involving migration of T cells to inflamed organs.

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