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Toshiyuki Matsunaga

Publications and source records attributed to Toshiyuki Matsunaga.

At least 19 recordsLinked to original sources
PubMed2007

Comparative characterization of pulmonary surfactant aggregates and alkaline phosphatase isozymes in human lung carcinoma tissue.

Alkaline phosphatase (AP) isozymes are surfactant-associated proteins (SPs). Since several different AP isozymes have been detected in the pneumocytes of lung cancer patients, we attempted to identify the relationship between pulmonary surfactant aggregate subtypes and AP isozymes. Pulmonary surfactant aggregates were isolated from carcinoma and non-carcinoma tissues of patients with non-small cell carcinoma of the lung. Upon analysis, ultraheavy, heavy, and light surfactant aggregates were detected in the non-carcinoma tissues, but no ultraheavy surfactant aggregates were found in the carcinoma tissues. Surfactant-associated protein A (SP-A) was detected as two bands (a 27-kDa band and a 54-kDa band) in the ultraheavy, heavy, and light surfactant aggregates found in the non-carcinoma tissues. Although both SP-A bands were detected in the heavy and light surfactant aggregates from adenocarcinoma tissues, the 54-kDa band was not detected in squamous cell carcinoma tissues. Liver AP (LAP) was detected in the heavy and light surfactant aggregates from both non-carcinoma and squamous carcinoma tissues, but not in heavy surfactant aggregates from adenocarcinoma tissues. A larger amount of bone type AP (BAP) was found in light surfactant aggregate fractions from squamous cell carcinomas than those from adenocarcinoma tissues or non-carcinoma tissues from patients with either type of cancer. LAP, BAP, and SP-A were identified immunohistochemically in type II pneumocytes from non-carcinoma tissues and adenocarcinoma cells, but no distinct SP-A staining was observed in squamous cell carcinoma tissues. The present study has thus revealed several differences in pulmonary surfactant aggregates and AP isozymes between adenocarcinoma tissue and squamous cell carcinoma tissue.

Alkaline Phosphatase↗
PubMed2006

Single structure widely distributed in a GeTe-Sb2Te3 pseudobinary system: a rock salt structure is retained by intrinsically containing an enormous number of vacancies within its crystal.

GeTe(1-x)-Sb2Te3(x) sputtered amorphous film was crystallized into a simple NaCl-type structure through instantaneous laser irradiation over a wide composition range from x = 0 to at least 2/3. When the ratio of Sb2Te3 increases, a vacancy is generated at every Na site for two Sb atoms. The fraction of vacancies, v(x), changes according to x/(1 + 2x), and the cubic root unit cell volume varies with a strong correlation to v(x). Through these created vacancies, valence electrons provided by adjacent Ge/Sb and Te atoms remain constant regardless of the composition, ensuring that these electrons occupy predominantly the bonding molecular orbitals. This results in crystal chemical stability, with the closed shell p-p bondings in the valence electrons arranging the crystal's atomic configuration into an NaCl-type structure.

Journal Article↗
PubMed2006

Molecular cloning of a novel type of rat cytoplasmic 17beta-hydroxysteroid dehydrogenase distinct from the type 5 isozyme.

Rat liver contains two cytosolic enzymes (TBER1 and TBER2) that reduce 6-tert-butyl-2,3-epoxy-5-cyclohexene-1,4-dione into its 4R- and 4S-hydroxy metabolites. In this study, we cloned the cDNA for TBER1 and examined endogenous substrates using the homogenous recombinant enzyme. The cDNA encoded a protein composed of 323 amino acids belonging to the aldo-keto reductase family. The recombinant TBER1 efficiently oxidized 17beta-hydroxysteroids and xenobiotic alicyclic alcohols using NAD+ as the preferred coenzyme at pH 7.4, and showed low activity towards 20alpha- and 3alpha-hydroxysteroids, and 9-hydroxyprostaglandins. The enzyme was potently inhibited by diethylstilbestrol, hexestrol and zearalenone. The coenzyme specificity, broad substrate specificity and inhibitor sensitivity of the enzyme differed from those of rat NADPH-dependent 17beta-hydroxysteroid dehydrogenase type 5, which was cloned from the liver and characterized using the recombinant enzyme. The mRNA for TBER1 was highly expressed in rat liver, gastrointestinal tract and ovary, in contrast to specific expression of 17beta-hydroxysteroid dehydrogenase type 5 mRNA in the liver and kidney. Thus, TBER1 represents a novel type of 17beta-hydroxysteroid dehydrogenase with unique catalytic properties and tissue distribution. In addition, TBER2 was identified as 3alpha-hydroxysteroid dehydrogenase on chromatographic analysis of the enzyme activities in rat liver cytosol and characterization of the recombinant 3alpha-hydroxysteroid dehydrogenase.

17-Hydroxysteroid Dehydrogenases↗
PubMed2006

Substrate specificity of a mouse aldo-keto reductase (AKR1C12).

AKR1C12, a mouse member of the aldo-keto reductase (AKR) superfamily, is highly expressed in the stomach and is identical to a protein encoded in an interleukin-3-regulated gene in mouse myeloid cells, but its function remains unknown. In this study, the recombinant AKR1C12 was purified to homogeneity and the specificity for coenzymes and substrates was examined at a physiological pH of 7.4. The enzyme reduced various alpha-dicarbonyl compounds, several ketosteroids, aldehydes and some ketones using NADH as the preferred coenzyme. In the reverse reaction, the enzyme showed coenzyme preference for NAD+, and oxidized 3alpha-, 17beta- and 20alpha-hydroxysteroids, and non-steroidal aliphatic and alicyclic alcohols, of which many hydroxysteroids and geranylgeraniol were good substrates, exhibiting low Km and high kcat/Km values. The results, together with the intracellular high ratio of NAD+/NADH, suggest that AKR1C12 functions as a dehydrogenase for the endogenous hydroxysteroids and geranylgeraniol in mouse stomach and myeloid cells.

Alcohol Oxidoreductases↗
PubMed2006

Enzymatic properties of a member (AKR1C20) of the aldo-keto reductase family.

AKR1C20, a member of the aldo-keto reductase (AKR) superfamily, found by mouse genomic analysis, exhibits the highest sequence identity (89%) with mouse liver 17beta-hydroxysteroid dehydrogenase (HSD) type 5, but its function remains unknown. In this report, we have expressed the recombinant AKR1C20 from its cDNA, and examined its properties. The purified enzyme was a 36-kDa monomer, and showed both 17beta-HSD and 3alpha-HSD activities in the presence of NADP(H) as the coenzymes. While the Km values for testosterone and 5alpha-dihydrotestosterone were high (>0.2 mM), those for 3alpha-hydroxy- and 3-keto-steroids were low (0.3-5 microM), resulting in high catalytic efficiency for the substrates. Although no significant dehydrogenase activity towards non-steroidal alcohols was observed, the enzyme highly reduced alpha-dicarbonyl compounds such as 16-ketoestrone, 9,10-phenanthrenequinone, acenaphthenequinone, 1-phenylisatin and camphorquinone. The pH optima of the dehydrogenase and reductase activities were 10.5 and 6.5-7.5, respectively. The enzyme was inhibited by sulfobromophthalein, hexestrol, indomethacin and flufenamic acid. The properties of AKR1C20 are distinct from those of previously known mouse 17beta-HSD type 5 (AKR1C6), 3alpha-HSD (AKR1C14) and other members of the AKR1C subfamily. Thus, AKR1C20 is a novel 3alpha(17beta)-HSD, which may also function as a reductase for xenobiotic alpha-dicarbonyl compounds.

17-Hydroxysteroid Dehydrogenases↗
PubMed2006

Multiplicity of mammalian reductases for xenobiotic carbonyl compounds.

A variety of carbonyl compounds are present in foods, environmental pollutants, and drugs. These xenobiotic carbonyl compounds are metabolized into the corresponding alcohols by many mammalian NAD(P)H-dependent reductases, which belong to the short-chain dehydrogenase/reductase (SDR) and aldo-keto reductase superfamilies. Recent genomic analysis, cDNA isolation and characterization of the recombinant enzymes suggested that, in humans, the six members of each of the two superfamilies, i.e., total of 12 enzymes, are involved in the reductive metabolism of xenobiotic carbonyl compounds. They comprise three types of carbonyl reductase, dehydrogenase/reductase (SDR family) member 4, 11beta-hydroxysteroid dehydrogenase type 1, L-xylulose reductase, two types of aflatoxin B1 aldehyde reductase, 20alpha-hydroxysteroid dehydrogenase, and three types of 3alpha-hydroxysteroid dehydrogenase. Accumulating data on the human enzymes provide new insights into their roles in cellular and molecular reactions including xenobiotic metabolism. On the other hand, mice and rats lack the gene for a protein corresponding to human 3alpha-hydroxysteroid dehydrogenase type 3, but instead possess additional five or six genes encoding proteins that are structurally related to human hydroxysteroid dehydrogenases. Characterization of the additional enzymes suggested their involvement in species-specific biological events and species differences in the metabolism of xenobiotic carbonyl compounds.

Alcohol Oxidoreductases↗
PubMed2005

Upregulation of immunoproteasomes by nitric oxide: potential antioxidative mechanism in endothelial cells.

Nitric oxide (*NO) was shown to stimulate the proteasomal function and the ubiquitin-proteasome pathway and to ameliorate endothelial apoptotic signaling induced by oxidants. Understanding the regulatory mechanisms by which *NO stimulates proteasomes and affords cytoprotection in endothelial cells has therapeutic implications, as many vascular diseases are characterized by a deficiency in *NO. Here we report that *NO/cGMP/cAMP-induced immunoproteasome subunit expression is responsible for the increased proteasomal activities. Cells pretreated with protein kinase G and protein kinase A inhibitors markedly attenuated *NO-dependent proteasome activation. Results show that the *NO/cGMP/cAMP signaling mechanism enhanced the phosphorylation of the transcription factor cAMP-response element-binding protein, elevated the cAMP-response element-promoter activity and induced the expression of immunoproteasomal subunits (LMP2 and LMP7). *NO-dependent proteasomal activity was abrogated in cells transfected with antisense LMP2 and LMP7 oligonucleotides. Lower levels of LMP2 and LMP7 were detected in aorta of iNOS(-/-) mice compared to wild-type controls, suggesting that endogenous production of *NO is important in the basal regulation of immunoproteasome. The *NO/cGMP/cAMP signaling pathway mitigates transferrin-iron-mediated oxidative stress and apoptosis through induction of immunoproteasomes. These results provide new insights on the regulatory mechanisms by which the *NO-mediated immunoproteasome signaling pathway affords cytoprotection in endothelial cells.

Animals↗
PubMed2005

Extremely long period-stacking structure in the Sb-Te binary system.

The crystal structure of the delta-phase in the Sb-Te binary system has been determined by synchrotron powder diffraction. It is clearly shown that many intermetallic compounds, which have different stacking periods depending on compound composition, exist in this phase. These structures are based on the cubic ABC stacking structure, and two kinds of fundamental structural units form an intergrowth along the stacking direction at the atomic level. The chemical formulae of these compounds are expressed as Sb(2n)Te3, where n is an integer and the number of stacking layers is 2n + 3. There is a relationship of inverse proportionality between the stacking period and the Te concentration.

Antimony↗
PubMed2005

Characterization of structural and catalytic differences in rat intestinal alkaline phosphatase isozymes.

To understand the differences between the rat intestinal alkaline phosphatase isozymes rIAP-I and rIAP-II, we constructed structural models based on the previously determined crystal structure for human placental alkaline phosphatase (hPLAP). Our models of rIAP-I and rIAP-II displayed a typical alpha/beta topology, but the crown domain of rIAP-I contained an additional beta-sheet, while the embracing arm region of rIAP-II lacked the alpha-helix, when each model was compared to hPLAP. The representations of surface potential in the rIAPs were predominantly positive at the base of the active site. The coordinated metal at the active site was predicted to be a zinc triad in rIAP-I, whereas the typical combination of two zinc atoms and one magnesium atom was proposed for rIAP-II. Using metal-depleted extracts from rat duodenum or jejunum and hPLAP, we performed enzyme assays under restricted metal conditions. With the duodenal and jejunal extract, but not with hPLAP, enzyme activity was restored by the addition of zinc, whereas in nonchelated extracts, the addition of zinc inhibited duodenal IAP and hPLAP, but not jejunal IAP. Western blotting revealed that nearly all of the rIAP in the jejunum extracts was rIAP-I, whereas in duodenum the percentage of rIAP-I (55%) correlated with the degree of AP activation (60% relative to that seen with jejunal extracts). These data are consistent with the presence of a triad of zinc atoms at the active site of rIAP-I, but not rIAP-II or hPLAP. Although no differences in amino acid alignment in the vicinity of metal-binding site 3 were predicted between the rIAPs and hPLAP, the His153 residue of both rIAPs was closer to the metal position than that in hPLAP. Between the rIAPs, a difference was observed at amino acid position 317 that is indirectly related to the coordination of the metal at metal-binding site 3 and water molecules. These findings suggest that the side-chain position of His153, and the alignment of Q317, might be the major determinants for activation of the zinc triad in rIAP-I.

Alkaline Phosphatase↗
PubMed2005

CLOCK/BMAL1 is involved in lipid metabolism via transactivation of the peroxisome proliferator-activated receptor (PPAR) response element.

Lipid absorption and metabolism are regulated by feeding and by the circadian system. It has been suggested that the expression of enzymes involved in lipid metabolism is directly controlled by the clock system. This study was designed to examine whether or not the CLOCK/BMAL1 heterodimer has transcriptional activity for genes via the peroxisome proliferator-activated receptor response element (PPRE). Male mice 8-12 weeks old were maintained under a 12:12 hour light-dark cycle for at least two weeks before the day of the experiment. The mRNA profiles of BMAL1 and of the PPAR target genes acyl-CoA oxidase (AOX), 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase and cellular retinol binding protein II (CRBPII) were measured in intestine. The direct effects of CLOCK/BMAL1 on the promoter activities of those three enzymes were assessed in vitro by luciferase assay. The expression of PPAR target genes changed in a cyclical manner that followed expression of BMAL1. The promoter activities of the three enzymes were increased by CLOCK/BMAL1 expression. After deletion of the PPRE from the CRBPII construct, CLOCK/BMAL1 did not affect transactivation. CLOCK/BMAL1 transactivates PPAR target genes via the PPRE.

ARNTL Transcription Factors↗
PubMed2004

Structures of stable and metastable Ge2Sb2Te5, an intermetallic compound in GeTe-Sb2Te3 pseudobinary systems.

The most widely used memory materials for rewritable phase-change optical disks are the GeTe-Sb2Te3 pseudobinary compounds. Among these compounds, Ge2Sb2Te5 crystallizes into a cubic close-packed structure with a six-layer period (metastable phase) in the non-thermal equilibrium state, and a trigonal structure with a nine-layer period (stable phase) in the thermal equilibrium state. The structure of the stable phase has Ge/Sb layers in which Ge and Sb are randomly occupied, as does the structure of the metastable phase, while the conventionally estimated structure had separate layers of Ge and Te. The metastable and stable phases are very similar in that Te and Ge/Sb layers stack alternately to form the crystal. The major differences between these phases are: (i) the stable phase has pairs of adjacent Te layers that are not seen in the metastable phase and (ii) only the metastable phase contains vacancies of ca 20 at. % in the Ge/Sb layers.

Journal Article↗
PubMed2004

Changes in receptor activator of nuclear factor-kappaB, and its ligand, osteoprotegerin, bone-type alkaline phosphatase, and tartrate-resistant acid phosphatase in ovariectomized rats.

We investigated time-course changes in the expression of receptor activator of nuclear factor-kappaB (RANK), its ligand (RANKL), osteoprotegerin (OPG), bone-type alkaline phosphatase (BAP), and tartrate-resistant acid phosphatase (TRAP) in ovariectomized (OVX) rats. Samples of sera and coccyges were used for analysis of the enzyme activities and expression levels of proteins and mRNAs, and an immunohistochemical analysis was also performed. Serum BAP activity increased to 158.6% of the pre-operation value at 1 week after OVX, and then decreased to 38.7% at 8 weeks after OVX. On the other hand, the serum TRAP activity increased to 130.9% of the pre-operation level at 1 week after OVX, and was maintained at a high level, compared with the pre-operation level. The patterns of BAP and TRAP activity in the coccyges specimens were similar to those seen in the sera. The expression profiles of TRAP, RANK, and RANKL proteins in the coccyx specimens were similar to the pattern of serum TRAP activity, while the profiles of the BAP and OPG proteins were similar to the pattern of serum BAP activity in OVX rats. The changes in the mRNA expression levels of the osteogenic proteins were similar to those for protein expression. These biochemical changes in OVX rats were confirmed by immunohistochemical studies. Our results suggest that not only osteoclastogenesis accelerated but also osteoblastogenesis transiently increased during the early phase of osteoporosis.

Acid Phosphatase↗
PubMed2004

Supplementation of endothelial cells with mitochondria-targeted antioxidants inhibit peroxide-induced mitochondrial iron uptake, oxidative damage, and apoptosis.

The mitochondria-targeted drugs mitoquinone (Mito-Q) and mitovitamin E (MitoVit-E) are a new class of antioxidants containing the triphenylphosphonium cation moiety that facilitates drug accumulation in mitochondria. In this study, Mito-Q (ubiquinone attached to a triphenylphosphonium cation) and MitoVit-E (vitamin E attached to a triphenylphosphonium cation) were used. The aim of this study was to test the hypothesis that mitochondria-targeted antioxidants inhibit peroxide-induced oxidative stress and apoptosis in bovine aortic endothelial cells (BAEC) through enhanced scavenging of mitochondrial reactive oxygen species, thereby blocking reactive oxygen species-induced transferrin receptor (TfR)-mediated iron uptake into mitochondria. Glucose/glucose oxidase-induced oxidative stress in BAECs was monitored by oxidation of dichlorodihydrofluorescein that was catalyzed by both intracellular H(2)O(2) and transferrin iron transported into cells. Pretreatment of BAECs with Mito-Q (1 microM) and MitoVit-E (1 microM) but not untargeted antioxidants (e.g. vitamin E) significantly abrogated H(2)O(2)- and lipid peroxide-induced 2',7'-dichlorofluorescein fluorescence and protein oxidation. Mitochondria-targeted antioxidants inhibit cytochrome c release, caspase-3 activation, and DNA fragmentation. Mito-Q and MitoVit-E inhibited H(2)O(2)- and lipid peroxide-induced inactivation of complex I and aconitase, TfR overexpression, and mitochondrial uptake of (55)Fe, while restoring the mitochondrial membrane potential and proteasomal activity. We conclude that Mito-Q or MitoVit-E supplementation of endothelial cells mitigates peroxide-mediated oxidant stress and maintains proteasomal function, resulting in the overall inhibition of TfR-dependent iron uptake and apoptosis.

Aconitate Hydratase↗
PubMed2004

Ceramide-induced intracellular oxidant formation, iron signaling, and apoptosis in endothelial cells: protective role of endogenous nitric oxide.

Sphingolipid ceramide (N-acetylsphingosine), a bioactive second messenger lipid, was shown to activate reactive oxygen species (ROS), mitochondrial oxidative damage, and apoptosis in neuronal and vascular cells. The proapoptotic effects of tumor necrosis factor-alpha, hypoxia, and chemotherapeutic drugs were attributed to increased ceramide formation. Here we investigated the protective role of nitric oxide (.NO) during hydrogen peroxide (H(2)O(2))-mediated transferrin receptor (TfR)-dependent iron signaling and apoptosis in C(2)-ceramide (C(2)-cer)-treated bovine aortic endothelial cells (BAECs). Addition of C(2)-cer (5-20 microm) to BAECs enhanced .NO generation. However, at higher concentrations of C(2)-cer (> or =20 microm), .NO generation did not increase proportionately. C(2)-cer (20-50 microm) also resulted in H(2)O(2)-mediated dichlorodihydrofluorescein oxidation, reduced glutathione depletion, aconitase inactivation, TfR overexpression, TfR-dependent uptake of (55)Fe, release of cytochrome c from mitochondria into cytosol, caspase-3 activation, and DNA fragmentation. N(w)-Nitro-l-arginine methyl ester (l-NAME), a nonspecific inhibitor of nitricoxide synthases, augmented these effects in BAECs at much lower (i.e. nonapoptotic) concentrations of C(2)-cer. The 26 S proteasomal activity in BAECs was slightly elevated at lower concentrations of C(2)-cer (< or =10 microm) but was greatly suppressed at higher concentrations (>10 microm). Intracellular scavengers of H(2)O(2), cell-permeable iron chelators, anti-TfR receptor antibody, or mitochondria-targeted antioxidant greatly abrogated C(2)-cer- and/or l-NAME-induced oxidative damage, iron signaling, and apoptosis. We conclude that C(2)-cer-induced H(2)O(2) and TfR-dependent iron signaling are responsible for its prooxidant and proapoptotic effects and that .NO exerts an antioxidative and cytoprotective role.

Animals↗
PubMed2004

Ambroxol reduces LPS toxicity mediated by induction of alkaline phosphatases in rat lung.

Alkaline phosphatases (APs) have been suggested to detoxify lipopolysaccharide (LPS) by dephosphorylation. Ambroxol, a bronchial expectorant, is known to accelerate the secretion of pulmonary surfactant particles including AP molecules as a pharmacological action. In the present study, some beneficial effects of ambroxol on LPS toxicity in the rat lung were investigated. In an experiment using the rat lung organ culture, AP activities were enhanced in a time-dependent manner by incubation with 25 microM of ambroxol in both the tissue and the medium. Western blot analysis indicated that AP activity was elevated by the treatment with ambroxol, due to the induction of surfactant proteins (SPs) and AP molecules. In the in vivo experiment, the serum LPS content was markedly increased after LPS administration to rats by intratracheal instillation of 20 mg/kg. However, when the rats were pretreated with oral ambroxol (1.0 mg/kg) at 1 h before LPS challenge, the area under the concentration--time curve (AUC) of serum LPS was significantly decreased. These results suggest that ambroxol inhibits the translocation of LPS from the lung into the circulation as well as its detoxification effect via the elevation of AP activity. Bromhexine, another expectorant, is less effective than ambroxol as an LPS detoxificant. Maintenance of high AP activity level in the lung suggests APs to have physiological significant effects against the inflammatory events induced by LPS.

Administration, Oral↗
PubMed2004

Characterization of the epitopes specific for the monoclonal antibody 9F5-3a and quantification of oxidized HDL in human plasma.

BACKGROUND: We previously isolated a monoclonal antibody, 9F5-3a, that is specific for HDL oxidized by CuSO(4). METHODS: We examined the characteristics of the 9F5-3a epitope by Western blot and measured the concentration of oxidized HDL in human plasma by enzyme-linked immunosorbent assay using this antibody. RESULTS: The monoclonal antibody specifically reacted with oxidized HDL in a mixture of HDL, LDL and modified lipoproteins. Oxidation of the HDL particles accelerated cross-linkage of apolipoproteins caused by lipid peroxidation, and the cross-linked apolipoprotein AI selectively reacted with the 9F5-3a antibody. Mean (standard deviation) plasma concentrations of oxidized HDL were 127 (50) microg/L in 23 healthy controls, 191 (65) microg/L in 30 patients with non-insulin-dependent diabetes mellitus (P < 0.01 versus healthy controls) and 200 (87) microg/L in 25 patients with coronary artery disease (P < 0.01 versus healthy controls). The concentrations of oxidized HDL did not correlate with the concentrations of thiobarbituric acid-reactive substances. CONCLUSIONS: The results indicate that determination of oxidized HDL concentration may be useful for identifying patients with atherosclerotic disease.

Adult↗
PubMed2003

NF-kappa B activation in endothelial cells treated with oxidized high-density lipoprotein.

We first determined whether oxidized high-density lipoprotein (ox-HDL) activates transcription factor nuclear factor-kappa B (NF-kappa B) in cultured human umbilical vein endothelial cells (HUVECs). Treatment for 7h with 100 microg/ml ox-HDL elicited a marked downregulation of I kappa B alpha and upregulation of the phosphorylated form of I kappa B alpha in HUVECs in a manner dependent on the dose of ox-HDL. Electrophoretic mobility shift assay in nuclear fraction from HUVECs showed translocation of NF-kappa B to the nucleus and binding of NF-kappa B to NF-kappa B consensus oligonucleotides during ox-HDL exposure for 7h, suggesting that ox-HDL brings about NF-kappa B activation in endothelial cells. To clarify the mechanism of NF-kappa B activation in HUVECs treated with ox-HDL, we investigated the effect of ox-HDL treatment on intracellular production of reactive oxygen species (ROS) in HUVECs. Ox-HDL induced a significant dose-dependent increase in ROS production during 4h incubation and this enhanced production of ROS was inhibited in the presence of probucol or diphenylene iodonium (DPI), an inhibitor of NADPH oxidase. In addition, pretreatment with probucol or DPI suppressed the phosphorylation and degradation of I kappa B alpha protein induced by ox-HDL, demonstrating that increased generation of ROS by ox-HDL may be associated with NF-kappa B activation. Pretreatment with antibody against oxidized low-density lipoprotein receptor-1 (LOX-1) significantly suppressed the ox-HDL-induced downregulation of I kappa B alpha, suggesting that LOX-1 mediates NF-kappa B activation in endothelial cells stimulated with ox-HDL. Taking all of the above findings together, ox-HDL activates NF-kappa B via binding to LOX-1 on the cell surface, followed by enhancement of intracellular ROS production in endothelial cells.

Blotting, Western↗