Inorganic Phosphate (Pi) Signaling in Endothelial Cells: A Molecular Basis for Generation of Endothelial Microvesicles in Uraemic Cardiovascular Disease
| Autor: | Karl E. Herbert, Nima Abbasian, Alan Bevington, Nigel J. Brunskill, James O. Burton, Alison H. Goodall |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
macromolecular substances
Catalysis Article Phosphates lcsh:Chemistry Inorganic Chemistry tropomyosin Cell-Derived Microparticles Pi Humans Protein Phosphatase 2 Physical and Theoretical Chemistry Cytoskeleton lcsh:QH301-705.5 Molecular Biology Spectroscopy Actin Cell Line Transformed Chemistry inorganic phosphate Organic Chemistry Endothelial Cells General Medicine Protein phosphatase 2 Microvesicles Computer Science Applications Cell biology PP2A Hyperphosphatemia Actin Cytoskeleton Cytoskeletal Proteins lcsh:Biology (General) lcsh:QD1-999 Cardiovascular Diseases Phosphorylation signaling microvesicles Intracellular Proto-oncogene tyrosine-protein kinase Src Signal Transduction Src DAPK-1 |
| Zdroj: | International Journal of Molecular Sciences Volume 21 Issue 19 International Journal of Molecular Sciences, Vol 21, Iss 6993, p 6993 (2020) |
| ISSN: | 1422-0067 |
| DOI: | 10.3390/ijms21196993 |
| Popis: | Hyperphosphataemia increases cardiovascular mortality in patients with kidney disease. Direct effects of high inorganic phosphate (Pi) concentrations have previously been demonstrated on endothelial cells (ECs), including generation of procoagulant endothelial microvesicles (MVs). However, no mechanism directly sensing elevated intracellular Pi has ever been described in mammalian cells. Here, we investigated the hypothesis that direct inhibition by Pi of the phosphoprotein phosphatase PP2A fulfils this sensing role in ECs, culminating in cytoskeleton disruption and MV generation. ECs were treated with control (1 mM [Pi]) vs. high (2.5 mM [Pi]), a condition that drives actin stress fibre depletion and MV generation demonstrated by confocal microscopy of F-actin and NanoSight Nanoparticle tracking, respectively. Immuno-blotting demonstrated that high Pi increased p-Src, p-PP2A-C and p-DAPK-1 and decreased p-TPM-3. Pi at 100 &mu M directly inhibited PP2A catalytic activity. Inhibition of PP2A enhanced inhibitory phosphorylation of DAPK-1, leading to hypophosphorylation of Tropomyosin-3 at S284 and MV generation. p-Src is known to perform inhibitory phosphorylation on DAPK-1 but also on PP2A-C. However, PP2A-C can itself dephosphorylate (and therefore inhibit) p-Src. The direct inhibition of PP2A-C by Pi is, therefore, amplified by the feedback loop between PP2A-C and p-Src, resulting in further PP2A-C inhibition. These data demonstrated that PP2A/Src acts as a potent sensor and amplifier of Pi signals which can further signal through DAPK-1/Tropomyosin-3 to generate cytoskeleton disruption and generation of potentially pathological MVs. |
| Databáze: | OpenAIRE |
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