2013
Andrysík, Zdeněk; Procházková, Jiřina; Kabátková, Markéta; Umannová, Lenka; Simečková, Pavlína; Kohoutek, Jiří; Kozubík, Alois; Machala, Miroslav; Vondráček, Jan
In: Archives of toxicology, vol. 87, no. 3, pp. 491–503, 2013, ISSN: 1432-0738 0340-5761, (Place: Germany).
Abstract | Links | BibTeX | Tags: Animals, Aryl Hydrocarbon/*agonists/genetics/metabolism, Benz(a)Anthracenes/toxicity, Carcinogens/*toxicity, Cell Communication/*drug effects, Cell Line, Cell Proliferation, Cell Transformation, Connexin 43/genetics/*metabolism, Contact Inhibition/*drug effects, Dose-Response Relationship, Down-Regulation, Drug, Epithelial Cells/*drug effects/metabolism/pathology, Fluorenes/toxicity, Gap Junctions/*drug effects/metabolism/pathology, Gene Knockdown Techniques, Indoles/pharmacology, Ligands, Liver Neoplasms/chemically induced/metabolism/pathology, Liver/*drug effects/metabolism/pathology, Neoplastic/chemically induced/metabolism/pathology, Phloroglucinol/analogs & derivatives/pharmacology, Phosphorylation, Polychlorinated Dibenzodioxins/toxicity, Proteasome Endopeptidase Complex/metabolism, Rats, Receptors, RNA Interference, Signal Transduction/*drug effects, Time Factors, Transfection
@article{andrysik_aryl_2013,
title = {Aryl hydrocarbon receptor-mediated disruption of contact inhibition is associated with connexin43 downregulation and inhibition of gap junctional intercellular communication.},
author = {Zdeněk Andrysík and Jiřina Procházková and Markéta Kabátková and Lenka Umannová and Pavlína Simečková and Jiří Kohoutek and Alois Kozubík and Miroslav Machala and Jan Vondráček},
doi = {10.1007/s00204-012-0963-7},
issn = {1432-0738 0340-5761},
year = {2013},
date = {2013-03-01},
journal = {Archives of toxicology},
volume = {87},
number = {3},
pages = {491–503},
abstract = {The aryl hydrocarbon receptor (AhR) contributes to the control of cell-to-cell communication, cell adhesion, migration or proliferation. In the present study, we investigated the regulation of connexin43 (Cx43) and Cx43-mediated gap junctional intercellular communication (GJIC) during the AhR-dependent disruption of contact inhibition in non-tumorigenic liver epithelial cells. The contact inhibition of cell proliferation is a process restricting the cell division of confluent non-transformed cells, which is frequently abolished in cancer cells; however, the mechanisms contributing to its disruption are still only partially understood. Disruption of contact inhibition, which was induced by toxic AhR ligands 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or polycyclic aromatic hydrocarbons in epithelial WB-F344 cells, reduced Cx43 protein levels, possibly via enhanced proteasomal degradation, significantly decreased the amount of gap junction plaques and downregulated GJIC, in an AhR-dependent manner. Although both intracellular and membrane Cx43 pools were markedly reduced in cells released from contact inhibition by TCDD, siRNA-mediated Cx43 knock-down was not sufficient to stimulate proliferation in contact-inhibited cells. Our data suggest that downregulation of Cx43/GJIC in non-transformed epithelial cells is an inherent part of disruption of contact inhibition, which occurs at the post-transcriptional level. This process runs in parallel with alterations of other forms of cell-to-cell communication, thus suggesting that toxic AhR agonists may simultaneously abrogate contact inhibition and reduce GJIC, two essential mechanisms linked to deregulation of cell-to-cell communication during tumor promotion and progression.},
note = {Place: Germany},
keywords = {Animals, Aryl Hydrocarbon/*agonists/genetics/metabolism, Benz(a)Anthracenes/toxicity, Carcinogens/*toxicity, Cell Communication/*drug effects, Cell Line, Cell Proliferation, Cell Transformation, Connexin 43/genetics/*metabolism, Contact Inhibition/*drug effects, Dose-Response Relationship, Down-Regulation, Drug, Epithelial Cells/*drug effects/metabolism/pathology, Fluorenes/toxicity, Gap Junctions/*drug effects/metabolism/pathology, Gene Knockdown Techniques, Indoles/pharmacology, Ligands, Liver Neoplasms/chemically induced/metabolism/pathology, Liver/*drug effects/metabolism/pathology, Neoplastic/chemically induced/metabolism/pathology, Phloroglucinol/analogs & derivatives/pharmacology, Phosphorylation, Polychlorinated Dibenzodioxins/toxicity, Proteasome Endopeptidase Complex/metabolism, Rats, Receptors, RNA Interference, Signal Transduction/*drug effects, Time Factors, Transfection},
pubstate = {published},
tppubtype = {article}
}
The aryl hydrocarbon receptor (AhR) contributes to the control of cell-to-cell communication, cell adhesion, migration or proliferation. In the present study, we investigated the regulation of connexin43 (Cx43) and Cx43-mediated gap junctional intercellular communication (GJIC) during the AhR-dependent disruption of contact inhibition in non-tumorigenic liver epithelial cells. The contact inhibition of cell proliferation is a process restricting the cell division of confluent non-transformed cells, which is frequently abolished in cancer cells; however, the mechanisms contributing to its disruption are still only partially understood. Disruption of contact inhibition, which was induced by toxic AhR ligands 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or polycyclic aromatic hydrocarbons in epithelial WB-F344 cells, reduced Cx43 protein levels, possibly via enhanced proteasomal degradation, significantly decreased the amount of gap junction plaques and downregulated GJIC, in an AhR-dependent manner. Although both intracellular and membrane Cx43 pools were markedly reduced in cells released from contact inhibition by TCDD, siRNA-mediated Cx43 knock-down was not sufficient to stimulate proliferation in contact-inhibited cells. Our data suggest that downregulation of Cx43/GJIC in non-transformed epithelial cells is an inherent part of disruption of contact inhibition, which occurs at the post-transcriptional level. This process runs in parallel with alterations of other forms of cell-to-cell communication, thus suggesting that toxic AhR agonists may simultaneously abrogate contact inhibition and reduce GJIC, two essential mechanisms linked to deregulation of cell-to-cell communication during tumor promotion and progression.
2009
Simecková, Pavlína; Vondrácek, Jan; Andrysík, Zdenek; Zatloukalová, Jirina; Krcmár, Pavel; Kozubík, Alois; Machala, Miroslav
The 2,2',4,4',5,5'-hexachlorobiphenyl-enhanced degradation of connexin 43 involves both proteasomal and lysosomal activities. Journal Article
In: Toxicological sciences : an official journal of the Society of Toxicology, vol. 107, no. 1, pp. 9–18, 2009, ISSN: 1096-0929, (Place: United States).
Abstract | Links | BibTeX | Tags: Analysis of Variance, Animals, Cell Communication/drug effects, Cell Line, Cell Membrane/drug effects, Connexin 43/genetics/*metabolism, Extracellular Signal-Regulated MAP Kinases/antagonists & inhibitors/metabolism, Gap Junctions/*drug effects/metabolism, Leupeptins/pharmacology, Liver/metabolism, Lysosomes/*drug effects/metabolism, Metabolic Networks and Pathways/drug effects, Polychlorinated Biphenyls/*pharmacology, Proteasome Endopeptidase Complex/*drug effects/metabolism, Proteasome Inhibitors, Rats
@article{simeckova_224455-hexachlorobiphenyl-enhanced_2009,
title = {The 2,2',4,4',5,5'-hexachlorobiphenyl-enhanced degradation of connexin 43 involves both proteasomal and lysosomal activities.},
author = {Pavlína Simecková and Jan Vondrácek and Zdenek Andrysík and Jirina Zatloukalová and Pavel Krcmár and Alois Kozubík and Miroslav Machala},
doi = {10.1093/toxsci/kfn202},
issn = {1096-0929},
year = {2009},
date = {2009-01-01},
journal = {Toxicological sciences : an official journal of the Society of Toxicology},
volume = {107},
number = {1},
pages = {9–18},
abstract = {One of the toxic effects of non-dioxin-like polychlorinated biphenyls (NDL-PCBs) is the acute inhibition of gap junctional intercellular communication (GJIC), an event possibly associated with tumor promotion. The model NDL-PCB-2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153)-induces a sustained GJIC inhibition in rat liver epithelial WB-F344 cells. As this effect might be related to deregulation of connexin 43 (Cx43) synthesis, trafficking, or degradation, we investigated the impact of PCB 153 on these events. Although PCB 153 had no effect on Cx43 mRNA levels, it induced a gradual loss of Cx43 protein and significantly decreased the amount of gap junction plaques in plasma membrane. PCB 153 contributed to extracellular signal-regulated kinases 1 and 2 (ERK1/2)-dependent accumulation of hyperphosphorylated Cx43-P3 form, thus indicating that ERK1/2 activation by PCB 153 might contribute to its effects on Cx43 internalization or degradation. Inhibition of either proteasomes or lysosomes with their specific inhibitors largely restored total Cx43 protein levels, thus suggesting that both proteasomes and lysosomes may participate in the PCB 153-enhanced Cx43 internalization and degradation. However, neither the proteasomal nor the lysosomal inhibitors restored normal GJIC or number/size of gap junction plaques. Finally, PCB 153 also interfered with restoration of gap junction plaques following the inhibition of Cx43 transport to plasma membrane. Taken together, multiple modes of action seem to contribute to downregulation of Cx43 in PCB 153-treated rat liver epithelial cells. The enhanced degradation of Cx43, together with persistent inhibition of GJIC, might contribute to tumor-promoting effects of NDL-PCBs.},
note = {Place: United States},
keywords = {Analysis of Variance, Animals, Cell Communication/drug effects, Cell Line, Cell Membrane/drug effects, Connexin 43/genetics/*metabolism, Extracellular Signal-Regulated MAP Kinases/antagonists & inhibitors/metabolism, Gap Junctions/*drug effects/metabolism, Leupeptins/pharmacology, Liver/metabolism, Lysosomes/*drug effects/metabolism, Metabolic Networks and Pathways/drug effects, Polychlorinated Biphenyls/*pharmacology, Proteasome Endopeptidase Complex/*drug effects/metabolism, Proteasome Inhibitors, Rats},
pubstate = {published},
tppubtype = {article}
}
One of the toxic effects of non-dioxin-like polychlorinated biphenyls (NDL-PCBs) is the acute inhibition of gap junctional intercellular communication (GJIC), an event possibly associated with tumor promotion. The model NDL-PCB-2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153)-induces a sustained GJIC inhibition in rat liver epithelial WB-F344 cells. As this effect might be related to deregulation of connexin 43 (Cx43) synthesis, trafficking, or degradation, we investigated the impact of PCB 153 on these events. Although PCB 153 had no effect on Cx43 mRNA levels, it induced a gradual loss of Cx43 protein and significantly decreased the amount of gap junction plaques in plasma membrane. PCB 153 contributed to extracellular signal-regulated kinases 1 and 2 (ERK1/2)-dependent accumulation of hyperphosphorylated Cx43-P3 form, thus indicating that ERK1/2 activation by PCB 153 might contribute to its effects on Cx43 internalization or degradation. Inhibition of either proteasomes or lysosomes with their specific inhibitors largely restored total Cx43 protein levels, thus suggesting that both proteasomes and lysosomes may participate in the PCB 153-enhanced Cx43 internalization and degradation. However, neither the proteasomal nor the lysosomal inhibitors restored normal GJIC or number/size of gap junction plaques. Finally, PCB 153 also interfered with restoration of gap junction plaques following the inhibition of Cx43 transport to plasma membrane. Taken together, multiple modes of action seem to contribute to downregulation of Cx43 in PCB 153-treated rat liver epithelial cells. The enhanced degradation of Cx43, together with persistent inhibition of GJIC, might contribute to tumor-promoting effects of NDL-PCBs.