ABSTRACT
Cadmium is a heavy metal that pollutes the environment and foods and is a risk factor for vascular disorders. We have previously demonstrated that pretreatment of vascular endothelial cells with zinc and copper protects the cells against cadmium cytotoxicity. In contrast, cadmium cytotoxicity was potentiated in cells following exposure to lead, thereby indicating that in vascular endothelial cells, cadmium cytotoxicity can be differentially modified by the co-occurrence of other heavy metals. In this study, we revealed that simultaneous treatment or pretreatment with manganese protects vascular endothelial cells against cadmium cytotoxicity. Intracellular accumulation of cadmium was observed to be reduced by simultaneous treatment with manganese, although not by pretreatment. The mRNA expression of metal transporters that regulate the uptake of both cadmium and manganese (ZIP8, ZIP14, and DMT1) remained unaffected by either simultaneous treatment or pretreatment with manganese, and simultaneous treatment with manganese suppressed the cadmium-induced expression of metallothionein but pretreatment with manganese did not exhibit such suppressive effect. Thus, the protection of vascular endothelial cells against cadmium cytotoxicity conferred by simultaneous treatment with manganese is assumed to be partially attributed to a reduction in the intracellular accumulation of cadmium, whereas the effects of pretreatment with manganese are independent of both the reduced intracellular accumulation of cadmium and the induction of metallothionein. These observations accordingly indicate that the protective effects of manganese are mediated via alternative (as yet unidentified) mechanisms.
Subject(s)
Endothelial Cells , Manganese , Metallothionein , Metallothionein/metabolism , Metallothionein/genetics , Endothelial Cells/drug effects , Endothelial Cells/metabolism , Cells, Cultured , Manganese/toxicity , Cadmium/toxicity , Cation Transport Proteins/genetics , Cation Transport Proteins/metabolism , RNA, Messenger/metabolism , RNA, Messenger/genetics , Humans , Animals , Cell Survival/drug effectsABSTRACT
Methylmercury is an environmental polluting organometallic compound that exhibits neurotoxicity, as observed in Minamata disease patients. Methylmercury damages peripheral nerves in Minamata patients, causing more damage to sensory nerves than motor nerves. Peripheral nerves are composed of three cell types: dorsal root ganglion (DRG) cells, anterior horn cells (AHCs), and Schwann cells. In this study, we compared cultured these three cell types derived from the rat for susceptibility to methylmercury cytotoxicity, intracellular accumulation of mercury, expression of L-type amino acid transporter 1 (LAT1), which transports methylmercury into cells, and expression of multidrug resistance-associated protein 2 (MRP2), which transports methylmercury-glutathione conjugates into the extracellular space. Of the cells examined, we found that DRG cells were the most susceptible to methylmercury with markedly higher intracellular accumulation of mercury. The constitutive level of LAT1 was higher and that of MRP2 lower in DRG cells compared with those in AHC and Schwann cells. Additionally, decreased cell viability caused by methylmercury was significantly reduced by either the LAT1 inhibitor, JPH203, or siRNA-mediated knockdown of LAT1. On the other hand, an MRP2 inhibitor, MK571, significantly intensified the decrease in the cell viability caused by methylmercury. Our results provide a cellular basis for sensory neve predominant injury in the peripheral nerves of Minamata disease patients.
Subject(s)
ATP-Binding Cassette Transporters , Cell Survival , Ganglia, Spinal , Methylmercury Compounds , Schwann Cells , Animals , Ganglia, Spinal/metabolism , Ganglia, Spinal/drug effects , Methylmercury Compounds/toxicity , Schwann Cells/drug effects , Schwann Cells/metabolism , Cell Survival/drug effects , Cells, Cultured , Large Neutral Amino Acid-Transporter 1/metabolism , Large Neutral Amino Acid-Transporter 1/genetics , Multidrug Resistance-Associated Proteins/metabolism , Multidrug Resistance-Associated Proteins/genetics , Peripheral Nerves/metabolism , Peripheral Nerves/drug effects , Male , Rats , Multidrug Resistance-Associated Protein 2ABSTRACT
Vascular endothelial cells serve as barriers between blood components and subendothelial tissue and regulate the blood coagulation-fibrinolytic system. Ionizing radiation is a common physical stimulant that induces a bystander effect whereby irradiated cells influence neighboring cells through signalings, including purinergic receptor signaling, activated by adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), and adenosine as secondary soluble factors. Human vascular endothelial EA.hy926 cells were cultured and irradiated with γ-rays or treated with ATP, ADP, or adenosine under non-toxic conditions. RNA-seq, gene ontology, and hierarchical clustering analyses were performed. The transcriptome analysis of differentially expressed genes in vascular endothelial cells after γ-ray irradiations suggests that the change of gene expression by γ-irradiation is mediated by ATP and ADP. In addition, the expression and activity of the proteins related to blood coagulation and fibrinolysis systems appear to be secondarily regulated by ATP and ADP in vascular endothelial cells after exposure to γ-irradiation. Although it is unclear whether the changes of the gene expression related to blood coagulation and fibrinolysis systems by γ-irradiation affected the increased hemorrhagic tendency through the exposure to γ-irradiation or the negative feedback to the activated blood coagulation system, the present data indicate that toxicity associated with γ-irradiation involves the dysfunction of vascular endothelial cells related to the blood coagulation-fibrinolytic system, which is mediated by the signalings, including purinergic receptor signaling, activated by ATP and ADP.
Subject(s)
Adenosine , Endothelial Cells , Humans , Adenosine/metabolism , Endothelial Cells/metabolism , Adenosine Triphosphate/metabolism , Receptors, Purinergic , Gene Expression Profiling , Adenosine Diphosphate/pharmacology , Cells, CulturedABSTRACT
Vascular endothelial cell growth is essential for the repair of intimal injury. Perlecan, a large heparan sulfate proteoglycan, intensifies fibroblast growth factor-2 (FGF-2) signaling as a co-receptor for FGF-2 and its receptor, and promotes the proliferation of vascular endothelial cells. Previously, we reported that 2 µM of lead, a toxic heavy metal, downregulated perlecan core protein expression and then suppressed the growth of vascular endothelial cells. However, since the mechanisms involved in the repression of perlecan by lead remains unclear, we analyzed its detailed signaling pathway using cultured bovine aortic endothelial cells. Our findings indicate that 2 µM of lead inhibited protein tyrosine phosphatase (PTP) activity and induced cyclooxygenase-2 (COX-2) via phosphorylation of the epidermal growth factor receptor (EGFR) and its downstream extracellular signal-regulated kinases (ERK1/2). In addition, among the prostanoids regulated by COX-2, prostaglandin I2 (PGI2) specifically contributes to the downregulation of perlecan expression by lead. This study revealed an intracellular pathway-the EGFR-ERK1/2-COX-2-PGI2 pathway activated by inhibition of PTP by lead-as a pathway that downregulates endothelial perlecan synthesis. The pathway is suggested to serve as a mechanism for the repression of perlecan expression, which leads to a delay in cell proliferation by lead.
Subject(s)
Endothelial Cells , Heparan Sulfate Proteoglycans , Animals , Cattle , Cyclooxygenase 2/genetics , Cyclooxygenase 2/metabolism , Endothelial Cells/metabolism , MAP Kinase Signaling System , Fibroblast Growth Factor 2/metabolism , Cells, Cultured , ErbB Receptors/metabolismABSTRACT
Granule cell-selective toxicity of methylmercury in the cerebellum is one of the main unresolved issues in the pathogenesis of Minamata disease. Rats were orally administered methylmercury chloride (10 mg/kg/day) for 5 consecutive days, and their brains were harvested on days 1, 7, 14, 21, or 28 after the last administration for histological examination of the cerebellum. It was found that methylmercury caused a marked degenerative change to the granule cell layers but not to the Purkinje cell layers. The generative change of the granule cell layer was due to cell death, including apoptosis, which occurred at day 21 and beyond after the methylmercury administration. Meanwhile, cytotoxic T-lymphocytes and macrophages had infiltrated the granule cell layer. Additionally, granule cells are shown to be a cell type susceptible to TNF-α. Taken together, these results suggest that methylmercury causes small-scale damage to granule cells, triggering the infiltration of cytotoxic T-lymphocytes and macrophages into the granule cell layer, which secrete tumor necrosis factor-α (TNF-α) to induce apoptosis in granule cells. This chain is established based on the susceptibility of granule cells to methylmercury, the ability of cytotoxic T lymphocytes and macrophages to synthesize and secrete TNF-α, and the sensitivity of granule cells to TNF-α and methylmercury. We propose to call the pathology of methylmercury-induced cerebellar damage the "inflammation hypothesis."
Subject(s)
Methylmercury Compounds , Rats , Animals , Methylmercury Compounds/toxicity , Methylmercury Compounds/metabolism , Tumor Necrosis Factor-alpha/metabolism , Cerebellum/metabolism , Neurons , ApoptosisABSTRACT
Lead (Pb) is an environmental pollutant that adversely affects various organs in the human body and is a well-known risk factor for cardiovascular diseases, caused by the dysfunction of vascular endothelial cells that cover the luminal surface of the blood vessels. The Zrt- and Irt-like related protein (ZIP) transporter ZIP8 is one of the primary importers of zinc, iron, manganese, and cadmium, and its expression appears to be important for the metabolism of these metals. In the present study, we investigated the influence of ZIP8 on Pb-induced cytotoxicity in vascular endothelial cells, induction of ZIP8 expression by Pb, and its mechanism of action in vascular endothelial cells. The study revealed the following: (1) Pb cytotoxicity in vascular endothelial cells was potentiated by the knockdown of ZIP8, but the intracellular accumulation of Pb in the cells remain unaffected; (2) Pb induced the expression of ZIP8; (3) the induction of ZIP8 expression by Pb was mediated by nuclear factor (NF)-κB signaling pathway; and (4) Pb activated p38, mitogen-activated protein kinase (MAPK), and c-jun N-terminal kinase (JNK), but the activation of these MAPKs was not involved in the induction of ZIP8 by Pb. Therefore, the study shows that Pb induces the expression of endothelial ZIP8 and this induction appears to be involved in the protection against Pb cytotoxicity by intracellular Pb accumulation independent mechanisms.
Subject(s)
Cation Transport Proteins , NF-kappa B , Humans , NF-kappa B/metabolism , Cation Transport Proteins/genetics , Cation Transport Proteins/metabolism , Endothelial Cells/metabolism , Lead/toxicity , Signal Transduction , Cells, CulturedABSTRACT
Cadmium is an environmental pollutant that adversely affects various organs in the human body and is a well-known risk factor for cardiovascular diseases. These disorders are caused by the dysfunction of the vascular endothelial cells that cover the luminal surface of blood vessels. The ZIP transporter ZIP8 is one of the primary importers of cadmium, and its expression appears to be important for the sensitivity of vascular endothelial cells to cadmium. In the present study, we investigated the influence of ZIP8 on cadmium-induced cytotoxicity in vascular endothelial cells, the induction of ZIP8 expression by cadmium, and its action mechanism in vascular endothelial cells. The study revealed that: (1) cadmium cytotoxicity in vascular endothelial cells was potentiated by the overexpression of ZIP8, and the intracellular accumulation of cadmium in the cells was increased; (2) cadmium highly induced the expression of ZIP8, but not other ZIPs; (3) lead and methylmercury moderately induced ZIP8 expression, but the other tested metals did not; (4) the induction of ZIP8 expression by cadmium was mediated by both NF-κB and JNK signaling, and the accumulation of NF-κB in the nucleus was regulated by JNK signaling. Particularly, it was found that cadmium activated NF-κB to transfer it into nuclei and activated JNK to stabilize NF-κB in nuclei, resulting in the induction of ZIP8 expression. This induction appears to be crucial for cadmium cytotoxicity in vascular endothelial cells.
Subject(s)
Cadmium/toxicity , Cation Transport Proteins/metabolism , MAP Kinase Kinase 4/metabolism , NF-KappaB Inhibitor alpha/metabolism , NF-kappa B/metabolism , Animals , Cation Transport Proteins/genetics , Cattle , Cells, Cultured , Endothelial Cells , Environmental Pollutants , Fibroblast Growth Factor 2 , Gene Expression Regulation/drug effects , Humans , MAP Kinase Kinase 4/genetics , NF-KappaB Inhibitor alpha/genetics , NF-kappa B/genetics , Signal TransductionABSTRACT
Transforming growth factor-ß1 (TGF-ß1) occurs at high levels at damage sites of vascular endothelial cell layers and regulates the functions of vascular endothelial cells. Reactive sulfur species (RSS), such as cysteine persulfide, glutathione persulfide, and hydrogen persulfide, are cytoprotective factors against electrophiles such as reactive oxygen species and heavy metals. Previously, we reported that sodium trisulfide, a sulfane sulfur donor, promotes vascular endothelial cell proliferation. The objective of the present study was to clarify the regulation and significance of RSS synthesis in vascular endothelial cells after exposure to TGF-ß1. Bovine aortic endothelial cells in a culture system were treated with TGF-ß1 to assess the expression of intracellular RSS, the effect of RSS on cell proliferation in the presence of TGF-ß1, induction of RSS-producing enzymes by TGF-ß1, and intracellular signal pathways that mediate this induction. The results suggest that TGF-ß1 increased intracellular RSS levels to modulate its inhibitory effect on proliferation. The increased production of RSS, probably high-molecular-mass RSS, was due to the induction of cystathionine γ-lyase and cystathionine ß-synthase, which are RSS-producing enzymes, and the induction was mediated by the ALK5-Smad2/3/4 and ALK5-Smad2/3-ATF4 pathways in vascular endothelial cells. TGF-ß1 regulates vascular endothelial cell functions such as proliferation and fibrinolytic activity; intracellular high-molecular-mass RSS, which are increased by TGF-ß1, may modulate the regulation activity in vascular endothelial cells.
Subject(s)
Cystathionine beta-Synthase/metabolism , Cystathionine gamma-Lyase/metabolism , Endothelial Cells/metabolism , Sulfur/metabolism , Transforming Growth Factor beta1/metabolism , Activating Transcription Factor 4/metabolism , Animals , Cattle , Cell Line , Cystathionine beta-Synthase/genetics , Cystathionine gamma-Lyase/genetics , Endothelial Cells/cytology , Gene Expression , Humans , Recombinant Proteins/metabolism , Signal Transduction , Smad Proteins/metabolism , Up-RegulationABSTRACT
Reactive sulfur species (RSS) include biological persulfide molecules that protect cells against oxidative stress and heavy metal toxicity. Vascular endothelial cells regulate blood coagulation and fibrinolytic activity, and prevent vascular disorders such as atherosclerosis. We hypothesized that RSS protect vascular endothelial cells not only from nonspecific cell damage but also from specific functional damage through regulation of specific cell functions. In the present study, cultured bovine aortic endothelial cells were treated with sodium trisulfide, a sulfane sulfur donor, and both [3H]thymidine incorporation and effects on cell cycle were analyzed. These results suggest that RSS stimulate vascular endothelial cell proliferation. RSS may reduce the functional cytotoxicity of antiproliferative agents.
Subject(s)
Cell Proliferation/drug effects , Endothelial Cells/drug effects , Endothelial Cells/metabolism , Sulfur/metabolism , Animals , Aorta/drug effects , Aorta/metabolism , CattleABSTRACT
Modulation of the blood coagulation fibrinolytic system is an essential function of vascular endothelial cells. Tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) are major fibrinolytic regulatory proteins synthesized by vascular endothelial cells; fibrinolytic activity is dependent on the balance between these proteins. Previously, we have reported that cadmium, an initiator of ischemic heart disease, induces PAI-1 expression and suppresses fibrinolytic activity in cultured human vascular endothelial cells. However, the key molecules involved in cadmium-induced PAI-1 induction remain unclear. Herein, we investigated the contribution of Smad2 and Smad3, transcriptional factors involved in PAI-1 induction via transforming growth factor-ß, using the human vascular endothelial cell line EA.hy926 cells in culture. Our findings indicated that cadmium induces PAI-1 expression without affecting t-PA expression up to 20 µM, a non-cytotoxic concentration, and PAI-1 induction by cadmium is partly mediated via Smad2 and Smad3. This study provides a possible mechanism underlying cadmium-induced vascular disorders.
Subject(s)
Cadmium/toxicity , Endothelial Cells/drug effects , Plasminogen Activator Inhibitor 1/metabolism , Smad2 Protein/metabolism , Smad3 Protein/metabolism , Cell Line , Cell Survival/drug effects , Endothelial Cells/metabolism , Humans , Plasminogen Activator Inhibitor 1/genetics , Signal Transduction/drug effects , Tissue Plasminogen Activator/metabolism , Umbilical Veins/cytologyABSTRACT
Vascular endothelial cells cover the luminal surface of blood vessels in a monolayer and play a role in the regulation of vascular functions, such as the blood coagulation-fibrinolytic system. When the monolayer is severely or repeatedly injured, platelets aggregate at the damaged site and release transforming growth factor (TGF)-ß1 in large quantities from their α-granules. Cadmium is a heavy metal that is toxic to various organs, including the kidneys, bones, liver, and blood vessels. Our previous study showed that the expression level of Zrt/Irt-related protein 8 (ZIP8), a metal transporter that transports cadmium from the extracellular fluid into the cytosol, is a crucial factor in determining the sensitivity of vascular endothelial cells to cadmium cytotoxicity. In the present study, TGF-ß1 was discovered to potentiate cadmium-induced cytotoxicity by increasing the intracellular accumulation of cadmium in cells. Additionally, TGF-ß1 induced the expression of ZIP8 via the activin receptor-like kinase 5-Smad2/3 signaling pathways; Smad3-mediated induction of ZIP8 was associated with or without p38 mitogen-activated protein kinase (MAPK). These results suggest that the cytotoxicity of cadmium to vascular endothelial cells increases when damaged endothelial monolayers that are highly exposed to TGF-ß1 are repaired.
Subject(s)
Blood Vessels , Cation Transport Proteins/metabolism , Endothelial Cells/metabolism , Receptor, Transforming Growth Factor-beta Type I/metabolism , Transforming Growth Factor beta/metabolism , Blood Vessels/cytology , Blood Vessels/metabolism , Cells, Cultured , Endothelial Cells/cytologyABSTRACT
Metallothionein (MT) is an inducible protein with cytoprotective activity against heavy metals such as cadmium, zinc, and copper. MT-1 and MT-2 are the isoforms of MT induced by and bind the heavy metals. Bovine aortic endothelial cells contain three types of MT genes, namely, MT-1A, MT-1E, and MT-2A; however, the associated protein expression of these MT isoforms has not been identified. In the present study, the expression of MT subisoform proteins in cells treated with cadmium chloride was identified using a high-performance liquid chromatography-inductively coupled plasma-mass spectrometry system. It was revealed that: (1) transcriptional induction of MT-1A by cadmium was markedly more sensitive than that of MT-1E/2A; (2) MT-1A and MT-2A proteins were the predominant MT subisoforms induced by cadmium; and (3) there might be differentiation in the functions of MT-1 and MT-2 against cadmium cytotoxicity, although the actual roles of the MT isoforms in the cells were not distinct. This is the first study to show the differential induction of isoforms of MT proteins in vascular endothelial cells by cadmium.
Subject(s)
Aorta/cytology , Cadmium Chloride/toxicity , Endothelial Cells/metabolism , Endothelium, Vascular/cytology , Metallothionein/genetics , Metallothionein/metabolism , Animals , Cattle , Cells, Cultured , Gene Expression/drug effects , Protein Isoforms/genetics , Protein Isoforms/metabolismABSTRACT
As toxic substances can enter the circulating blood and cross endothelial monolayers to reach parenchymal cells in organs, vascular endothelial cells are an important target compartment for such substances. Reactive sulfur species protect cells against oxidative stress and toxic substances, including heavy metals. Reactive sulfur species are produced by enzymes, such as cystathionine γ-lyase (CSE), cystathionine ß-synthase, 3-mercaptopyruvate sulfurtransferase, and cysteinyl-tRNA synthetase. However, little is known about the regulatory mechanisms underlying the expression of these enzymes in vascular endothelial cells. Bio-organometallics is a research field that analyzes biological systems using organic-inorganic hybrid molecules (organometallic compounds and metal coordinating compounds) as molecular probes. In the present study, we analyzed intracellular signaling pathways that mediate the expression of reactive sulfur species-producing enzymes in cultured bovine aortic endothelial cells, using copper diethyldithiocarbamate (Cu10). Cu10 selectively upregulated CSE gene expression in vascular endothelial cells independent of cell density. This transcriptional induction of endothelial CSE required both the diethyldithiocarbamate scaffold and the coordinated copper ion. Additionally, the present study revealed that ERK1/2, p38 MAPK, and hypoxia-inducible factor (HIF)-1α/HIF-1ß pathways mediate transcriptional induction of endothelial CSE by Cu10. The transcription factors NF-κB, Sp1, and ATF4 were suggested to act in constitutive CSE expression, although the possibility that they are involved in the CSE induction by Cu10 cannot be excluded. The present study used a copper complex as a molecular probe to reveal that the transcription of CSE is regulated by multiple pathways in vascular endothelial cells, including ERK1/2, p38 MAPK, and HIF-1α/HIF-1ß. Bio-organometallics appears to be an effective strategy for analyzing the functions of intracellular signaling pathways in vascular endothelial cells.
Subject(s)
Cystathionine gamma-Lyase/genetics , Ditiocarb/pharmacology , Animals , Aryl Hydrocarbon Receptor Nuclear Translocator/genetics , Aryl Hydrocarbon Receptor Nuclear Translocator/metabolism , Cattle , Cells, Cultured , Copper/chemistry , Cystathionine gamma-Lyase/metabolism , Ditiocarb/chemistry , Endothelial Cells/drug effects , Endothelial Cells/metabolism , Endothelium, Vascular/cytology , Gene Expression Regulation, Enzymologic/drug effects , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , MAP Kinase Signaling System/drug effects , Sulfur/metabolismABSTRACT
Vascular endothelial cells cover the luminal surface of blood vessels in a monolayer. Proliferation of these cells is crucial for the repair of damaged endothelial monolayers. In the present study, we identified a zinc complex, Zn(ii)2,9-dimethyl-1,10-phenanthroline (Zn-12), that stimulates the proliferation of bovine aortic endothelial cells in a culture system. No such stimulatory activity was observed for the ligand alone or in combination with other metals; however, the ligand combined with iron weakly stimulated the proliferation, as evidenced by the [3H]thymidine incorporation assay. Inorganic zinc weakly but significantly stimulated proliferation, and intracellular accumulation of zinc was similar between inorganic zinc and Zn-12 treatment, suggesting that the mechanisms by which Zn-12 stimulates vascular endothelial cell proliferation contain processes that differ from those by which inorganic zinc stimulates proliferation. Although expression of endogenous fibroblast growth factor-2 (FGF-2) and its receptor FGFR-1 was unchanged by Zn-12, both siRNA-mediated knockdown of FGF-2 and FGFR inhibition partly but significantly suppressed the stimulation of vascular endothelial cell proliferation by Zn-12, indicating that the zinc complex activates the FGF-2 pathway to stimulate proliferation. Phosphorylation of ERK1/2 and MAPKs was induced by Zn-12, and PD98059, a MEK1 inhibitor, significantly suppressed the stimulatory effect of Zn-12 on vascular endothelial cell proliferation. Therefore, it is suggested that Zn-12 activates the FGF-2 pathway via activation of ERK1/2 signaling to stimulate vascular endothelial cell proliferation, although FGF-2-independent mechanisms are also involved in the stimulation. Zn-12 and related compounds may be promising molecular probes to analyze biological systems of vascular endothelial cells.
ABSTRACT
Metallothionein (MT) is a low-molecular-weight, cysteine-rich, and metal-binding protein that protects cells from the cytotoxic effects of heavy metals and reactive oxygen species. Previously, we found that transcriptional induction of endothelial MT-1A was mediated by not only the metal-regulatory transcription factor 1 (MTF-1)-metal responsive element (MRE) pathway but also the nuclear factor-erythroid 2-related factor 2 (Nrf2)-antioxidant response element/electrophile responsive element (ARE) pathway, whereas that of MT-2A was mediated only by the MTF-1-MRE pathway, using the organopnictogen compounds tris(pentafluorophenyl)stibane, tris(pentafluorophenyl)arsane, and tris(pentafluorophenyl)phosphane as molecular probes in vascular endothelial cells. In the present study, we investigated the binding sites of MTF-1 and Nrf2 in the promoter regions of MTs in cultured bovine aortic endothelial cells treated with these organopnictogen compounds. We propose potential mechanisms underlying transcriptional induction of endothelial MT isoforms. Specifically, both MRE activation by MTF-1 and that of ARE in the promoter region of the MT-2A gene by Nrf2 are involved in transcriptional induction of MT-1A, whereas only MRE activation by MTF-1 or other transcriptional factor(s) is required for transcriptional induction of MT-2A in vascular endothelial cells.
Subject(s)
Endothelial Cells/drug effects , Metallothionein/genetics , Phosphines/toxicity , Animals , Aorta/cytology , Cattle , Cells, Cultured , DNA-Binding Proteins/genetics , Endothelial Cells/metabolism , NF-E2-Related Factor 2/genetics , Protein Isoforms/genetics , Transcription Factors/genetics , Transcription, Genetic , Transcription Factor MTF-1ABSTRACT
AIM: Our recent case report of organotin intoxication showed higher ratio of urinary trimethyl tin (TMT) to dimethyl tin (DMT) than those of the previous cases exposed to only DMT, suggesting co-exposure to DMT and TMT occurred. The present study investigated how urinary TMT and DMT reflect blood TMT and DMT, respectively, to evaluate them as biomarkers for TMT/DMT exposure. METHODS: DMT and TMT from blood collected at different time points from three patients intoxicated with organotins were measured with HPLC-ICP/MS. Previously published data of urinary DMT and TMT were used for comparison. Regression analyses were conducted with dependent variable of blood DMT and TMT and independent variable of urinary DMT and TMT, respectively. Multiple regression analysis with dummy variables of individual was also conducted. RESULTS: Regression analysis did not show significant relation of urinary TMT to blood TMT or relation of urinary DMT to blood DMT, although the former was marginal. Multiple regression analysis showed significantly positive relation of urinary TMT to blood TMT. CONCLUSIONS: The study shows that urinary TMT reflects blood TMT. In co-exposure to TMT and DMT, urinary TMT can be an internal exposure marker of TMT, which might be not only derived from external exposure to TMT but also converted from DMT in human body.
Subject(s)
Occupational Exposure/analysis , Tin/blood , Tin/urine , Trimethyltin Compounds/blood , Trimethyltin Compounds/urine , Adult , Biomarkers/blood , Biomarkers/urine , Female , Humans , Male , Organotin Compounds/analysis , Recycling , Regression AnalysisABSTRACT
Although cytotoxicity of inorganic metals has been well investigated, little is known about the cytotoxicity of organic-inorganic hybrid molecules. The cytotoxicity of zinc complexes was evaluated using a culture system of vascular endothelial cells. We found that bis(1,4-dihydro-2-methyl-1-phenyl-4-thioxo-3-pyridiolato)zinc(II), termed Zn-06, exhibited strong cytotoxicity in vascular smooth muscle cells, epithelial cells, fibroblastic cells, and vascular endothelial cells. This study showed that the tetracoordinate structure of the Zn-06 molecule, which contains two sulfur and two oxygen atoms attached to the zinc atom, facilitated its accumulation within vascular endothelial cells whereas the whole structure of the zinc complex was involved in its cytotoxicity in the cells. The present data suggest that a part of the structure, especially the binding site of the metal atom, was responsible for accumulation of zinc complexes, and the entire structure is responsible for their cytotoxicity in vascular endothelial cells.
Subject(s)
Endothelial Cells/drug effects , Zinc Compounds/toxicity , Animals , Cattle , Cell Survival/drug effects , Cells, Cultured , Epithelial Cells/drug effects , Fibroblasts/drug effects , Humans , Myocytes, Smooth Muscle/drug effects , SwineABSTRACT
Proteoglycans synthesized by vascular endothelial cells are important for regulating cell function and the blood coagulation-fibrinolytic system. Since we recently reported that copper(II) bis(diethyldithiocarbamate) (Cu(edtc)2) modulates the expression of some molecules involving the antioxidant and blood coagulation systems, we hypothesized that Cu(edtc)2 may regulate the expression of proteoglycans and examined this hypothesis using a bovine aortic endothelial cell culture system. The experiments showed that Cu(edtc)2 induced the expression of syndecan-4, a transmembrane heparan sulfate proteoglycan, in a dose- and time-dependent manner. This induction required the whole structure of Cu(edtc)2-the specific combination of intramolecular copper and a diethyldithiocarbamate structure-as the ligand. Additionally, the syndecan-4 induction by Cu(edtc)2 depended on the activation of p38 mitogen-activated protein kinase (MAPK) but not the Smad2/3, NF-E2-related factor2 (Nrf2), or epidermal growth factor receptor (EGFR) pathways. p38 MAPK may be a key molecule for inducing the expression of syndecan-4 in vascular endothelial cells.
Subject(s)
Endothelial Cells/drug effects , Organometallic Compounds/pharmacology , Syndecan-4/metabolism , p38 Mitogen-Activated Protein Kinases/metabolism , Animals , Cattle , Cells, Cultured , Copper/chemistry , Ditiocarb/analogs & derivatives , Endothelial Cells/metabolism , Endothelium, Vascular/metabolism , Syndecan-4/geneticsABSTRACT
Organic-inorganic hybrid molecules, which are composed of organic-ligand(s) and metal(s), are indispensable as synthetic reagents in chemistry, but they have made very little in the way of contributions to biological research. Previously, we reported that the cytotoxicity of organic-inorganic hybrid molecules in vascular endothelial cells depends on interactions between the intramolecular metal and ligand, but remains independent of the hydrophobicity of the intramolecular metal(s). Herein, we show a synergistic cytotoxicity produced by forming a complex of copper and 2,9-dimethyl-1,10-phenanthroline in vascular endothelial cells that depends on the intracellular accumulation of copper.
Subject(s)
Coordination Complexes/toxicity , Copper/toxicity , Endothelial Cells/drug effects , Ligands , Organometallic Compounds/toxicity , Phenanthrolines/toxicity , Animals , Cattle , Cells, Cultured , Coordination Complexes/metabolism , Copper/metabolism , Drug Synergism , Endothelial Cells/metabolism , Hydrophobic and Hydrophilic Interactions , Organometallic Compounds/metabolism , Phenanthrolines/metabolismABSTRACT
Recent developments have shown that organic-inorganic hybrid molecules have the potential to provide useful tools for analyzing biological systems. In the case of fibrinolysis, which is the phenomenon whereby fibrin is degraded by plasmin that has been converted from plasminogen via tissue plasminogen activator (t-PA) secreted from vascular endothelial cells, we hypothesized that there may be organic-inorganic hybrid molecules that could be used to analyze the mechanisms by which endothelial fibrinolysis is regulated. In our present study, we found that a copper complex - copper diethyldithiocarbamate (Cu10) - reduces t-PA activity in a conditioned medium of cultured human coronary endothelial cells by inhibiting the t-PA synthesis without changing the synthesis of plasminogen activator inhibitor type 1, which is a t-PA inhibitor. Copper sulfate, the Cu10 ligand, and zinc/iron complexes with the same Cu10 ligand, did not exhibit such biological activity. These results indicate that Cu10 has the potential to provide a useful tool for finding alternative pathways that downregulate endothelial t-PA synthesis.