Oxidative stress induces actin-cytoskeletal and tight-junctional alterations in hepatocytes by a Ca2+ -dependent, PKC-mediated mechanism: protective effect of PKA
| Autor: | Marcelo G. Roma, Enrique J. Sánchez Pozzi, Justina E. Ochoa, Jalal Ahmed-Choudhury, Leonardo Martín Pérez, Roger Coleman, Elwyn Elias, Piotr Milkiewicz |
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| Rok vydání: | 2005 |
| Předmět: |
Male
medicine.disease_cause Biochemistry Tight Junctions chemistry.chemical_compound BAPTA tert-Butylhydroperoxide Dichlorofluorescein Physiology (medical) medicine Staurosporine Animals Rats Wistar Cytoskeleton Protein kinase C Protein Kinase C Chemistry Cyclic AMP-Dependent Protein Kinases Actins Cell biology Rats Enzyme Activation Oxidative Stress medicine.anatomical_structure Hepatocyte Hepatocytes Calcium Intracellular Oxidative stress medicine.drug |
| Zdroj: | Free radical biologymedicine. 40(11) |
| ISSN: | 0891-5849 |
| Popis: | Oxidative stress elevates Ca2+ and, presumably, activates Ca2+ -dependent PKCs. We analyzed the participation of Ca2+ -dependent PKCs in actin disorganization and tight-junctional impairment induced by the pro-oxidant tert-butylhydroperoxide (tBOOH) in isolated rat hepatocyte couplets. tBOOH (100 microM) augmented radical oxygen species (ROS), as indicated by increased lipid peroxidation (+217%, p < 0.05) and intracellular production of 2',7'-dichlorofluorescein (+36%, p < 0.05). Cytosolic Ca2+ and PKCalpha translocation to membrane, an indicator of PKCalpha activation, were also elevated by tBOOH (+100 and +79%, respectively, p < 0.05). tBOOH increased the number of couplets displaying membrane blebs (+278%, p < 0.001) and caused redistribution of F-actin. tBOOH induced tight-junctional impairment, as indicated by a reduction in the percentage of couplets retaining presecreted cholyllysylfluorescein in their canalicular vacuoles (-54%, p < 0.001). tBOOH induced redistribution of the tight-junctional-associated protein ZO-1. All these events were prevented by the panspecific PKC inhibitors H7 and staurosporine, the Ca2+ -dependent PKC inhibitor Go6976, the intracellular Ca2+ chelator BAPTA/AM, and the PKA activator dibutyryl-cyclic AMP. Furthermore, PKC inhibition and PKA activation not only prevented but also fully reversed tBOOH-induced blebbing. Conversely, tBOOH-induced ROS formation and Ca2+ elevation remained unchanged. We conclude that ROS induce hepatocellular actin-cytoskeleton rearrangement and tight-junctional impairment by a PKC-mediated, Ca2+ -dependent mechanism, which is counteracted by PKA. |
| Databáze: | OpenAIRE |
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