Biomedical subjects

K Ohashi

Publications and source records attributed to K Ohashi.

At least 73 records · Page 4Linked to original sources

PubMed2001

Phylogenetic relationships of bovine immunodeficiency virus in cattle and buffaloes based on surface envelope gene sequences. Brief report.

Isolates of bovine immunodeficiency virus (BIV) exhibit a striking genomic diversity, most of which are located in the viral envelope gene. Since this property of the BIV group of viruses may play an important role in the pathobiology of the virus, the surface envelope gene, particularly the conserved (C) 2, hypervariable (V) 1, V2 and C3 regions, of eleven different isolates from different environments with different bovine breeds naturally infected with BIV, including dairy cows in Japan, buffaloes in Pakistan and draught animals in Cambodia, were sequenced. When compared to the nucleotide sequence of American BIV isolates, all Asian BIV field isolates seem to be smaller, several base substitutions were observed in the V1 region, and deletions were also found in the V2 region of env gene in these samples. However, deduced amino acid sequences were not so different among isolates from different bovine breeds, suggesting that bovine susceptibility to BIV infection may not depend upon bovine breed or buffaloes. Moreover, phylogenetic analysis revealed that genotypes were distinct between Asian and American BIV isolates and these results also provide an information on the molecular epidemiology of naturally occurring BIV infection in cattle and buffaloes.

Amino Acid Sequence↗

PubMed2001

Gas6 regulates mesangial cell proliferation through Axl in experimental glomerulonephritis.

Proliferation of mesangial cells is a hallmark of glomerular disease, and understanding its regulatory mechanism is clinically important. Previously, we demonstrated that the product of growth arrest-specific gene 6 (Gas6) stimulates mesangial cell proliferation through binding to its cell-surface receptor Axl in vitro. We also showed that warfarin and the extracellular domain of Axl conjugated with Fc portion of human IgG1 (Axl-Fc) inhibit mesangial cell proliferation by interfering the Gas6/Axl pathway in vitro. In the present study, therefore, we examined in vivo roles of Gas6 and Axl in an experimental model of mesangial proliferative glomerulonephritis induced by the injection of anti-Thy1.1 antibody (Thy1 GN). In Thy1 GN, expression of Gas6 and Axl was markedly increased in glomeruli, and paralleled the progression of mesangial cell proliferation. Administration of warfarin or daily injection of Axl-Fc inhibited mesangial cell proliferation, and abolished the induction of platelet-derived growth factor-B mRNA and protein in Thy1 GN. Moreover, the anti-proliferative effect of warfarin was achieved at lower concentrations than those in routine clinical use. These findings indicate that the Gas6/Axl pathway plays a key role in mesangial cell proliferation in vivo, and could be a potentially important therapeutic target for the treatment of renal disease.

Animals↗

PubMed2001

The LDL receptor is the major pathway for beta-VLDL uptake by mouse peritoneal macrophages.

In order to determine the contribution of the low density lipoprotein receptor (LDL-R) to the removal of apoB-containing native lipoproteins by macrophages, we compared the uptake of beta-VLDL in peritoneal macrophages (MPM) from wild type mice and mice lacking the LDL-R. The d<1.006 g/ml lipoproteins obtained from apoE deficient mice fed a high fat diet were poorly degraded by macrophages and caused only a slight formation of CE in macrophages from both types of mice. On the other hand, d<1.006 g/ml lipoproteins obtained from LDL-R deficient mice fed a high fat diet, beta-VLDL with apoE, were avidly taken up by and markedly stimulated CE formation in wild type macrophages, but not in macrophages lacking the LDL-R. The degradation of 125I-labeled-apoE-containing beta-VLDL by wild type MPM was poorly inhibited by unlabeled human LDL, and beta-VLDL without apoE had no effects. In conclusion, we propose that the in vitro uptake of native apoE-enriched lipoproteins by murine macrophages is primarily mediated by the LDL receptor and not by other apoE-recognizing receptor systems such as: the LDL receptor related protein, the VLDL receptor or the triglyceride-rich lipoprotein receptor.

Animals↗

PubMed2001

Analysis of anti-rotavirus activity of extract from Stevia rebaudiana.

Anti-human rotavirus (HRV) activity of hot water extracts from Stevia rebaudiana (SE) was examined. SE inhibited the replication of all four serotypes of HRV in vitro. This inhibitory effect of SE was not reduced on the prior exposure of SE to HCl for 30 min at pH 2. Binding assay with radiolabeled purified viruses indicated that the inhibitory mechanism of SE is the blockade of virus binding. The SE inhibited the binding of anti-VP7 monoclonal antibody to HRV-infected MA104 cells. The inhibitory components of SE were found to be heterogeneous anionic polysaccharides with different ion charges. The component analyses suggested that the purified fraction named as Stevian with the highest inhibitory activity consists of the anionic polysaccharide with molecular weight of 9800, and contains Ser and Ala as amino acids. Analyses of sugar residues suggest uronic acid(s) as sugar components. It did not contain amino and neutral sugars and sulfate residues. These findings suggest that SE may bind to 37 kD VP7 and interfere with the binding of VP7 to the cellular receptors by steric hindrance, which results in the blockade of the virus attachment to cells.

Animals↗

PubMed2001

Occlusal hypofunction causes changes of proteoglycan content in the rat periodontal ligament.

The biological functions of proteoglycans and glycosaminoglycans are closely associated with mechanical stress on the tissue. In order to reveal the relationship between proteoglycans in the periodontal ligament and mechanical stress such as occlusal stimuli, occlusal hypofunction of rat unilateral mandibular molars was induced by extraction of the opposing first, second and third maxillary molars. Immunohistochemical analyses were performed using antibodies for chondroitin sulfate, decorin, biglycan, heparan sulfate and keratan sulfate, and hyaluronic acid-binding protein. Chondroitin sulfate, observed more strongly in the cervical side than in the apical side of the periodontal ligament of the unextracted sides of mandible, and uniformly present in the extracellular matrix of the periodontal ligament, decreased significantly from 1 wk post-extraction of the antagonists, with a decrease in thickness and disarrangement in fibrous components. Decorin core protein, uniformly present in the periodontal ligament of the unextracted sides, decreased as early on as 2 d post-extraction. Heparan sulfate, mainly localized on the cell surface of vascular endothelial cells and osteoclastic cells as well as in the extracellular matrix of the unextracted sides, decreased significantly in association with the decreased number of blood vessels and osteoclastic cells as early on as 2 d post-extraction. Biglycan, keratan sulfate and hyaluronic acid, uniformly distributed in the periodontal ligament of the unextracted sides, showed little change after the extraction. These results demonstrate that occlusal hypofunction causes tissue remodeling of the periodontal ligament, with a significant decrease of chondroitin sulfate, decorin and heparan sulfate.

Animals↗

PubMed2001

Phosphorylation of cofilin by LIM-kinase is necessary for semaphorin 3A-induced growth cone collapse.

Semaphorin 3A is a chemorepulsive axonal guidance molecule that depolymerizes the actin cytoskeleton and collapses growth cones of dorsal root ganglia neurons. Here we investigate the role of LIM-kinase 1, which phosphorylates an actin-depolymerizing protein, cofilin, in semaphorin 3A-induced growth cone collapse. Semaphorin 3A induced phosphorylation and dephosphorylation of cofilin at growth cones sequentially. A synthetic cell-permeable peptide containing a cofilin phosphorylation site inhibited LIM-kinase in vitro and in vivo, and essentially suppressed semaphorin 3A-induced growth cone collapse. A dominant-negative LIM kinase, which could not be activated by PAK or ROCK, suppressed the collapsing activity of semaphorin 3A. Phosphorylation of cofilin by LIM-kinase may be a critical signaling event in growth cone collapse by semaphorin 3A.

Actin Depolymerizing Factors↗

PubMed2001

Identification of a novel gene, Mblk-1, that encodes a putative transcription factor expressed preferentially in the large-type Kenyon cells of the honeybee brain.

Mushroom bodies (MBs) are considered to be involved in higher-order sensory processing in the insect brain. To identify the genes involved in the intrinsic function of the honeybee MBs, we searched for genes preferentially expressed therein, using the differential display method. Here we report a novel gene encoding a putative transcription factor (Mblk-1) expressed preferentially in one of two types of intrinsic MB neurones, the large-type Kenyon cells, which makes Mblk-1 a candidate gene involved in the advanced behaviours of honeybees. A putative DNA binding motif of Mblk-1 had significant sequence homology with those encoded by genes from various animal species, suggesting that the functions of these proteins in neural cells are conserved among the animal kingdom.

Amino Acid Sequence↗

PubMed2001

Effects of CYP2C19 genotypic differences in the metabolism of omeprazole and rabeprazole on intragastric pH.

BACKGROUND: Omeprazole is mainly metabolized in the liver by CYP2C19, a genetically determined enzyme, whereas rabeprazole is mainly reduced non-enzymatically and partially metabolized by CYP2C19. The therapeutic effects of rabeprazole are therefore assumed to be less affected by an individual's CYP2C19 status. AIM: To investigate the acid inhibitory effects and plasma levels of omeprazole and rabeprazole with reference to different CYP2C19 genotypes. METHODS: Fifteen healthy volunteers took a daily dose of 20 mg of omeprazole or rabeprazole for 8 days. On post-dose days 1 and 8, 24-h profiles of intragastric pH were recorded and plasma concentrations of omeprazole, rabeprazole and their metabolites were determined. RESULTS: After single and repeated doses of omeprazole, the intragastric pH values and plasma concentrations of omeprazole and its metabolites were significantly dependent on the CYP2C19 genotype. Significant differences in the same kinetic and dynamic parameters were also observed after single doses of rabeprazole. Although the plasma levels of rabeprazole differed among the different CYP2C19 genotype groups after repeated doses, no significant differences in intragastric pH values were observed. CONCLUSIONS: The acid inhibitory effects of omeprazole and rabeprazole are significantly dependent on the CYP2C19 genotype status, as well as on their intrinsic pharmacokinetic and pharmacodynamic characteristics and dosing schemes.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2001

Pathogenesis of beta2-microglobulin amyloidosis.

Hemodialysis-related amyloidosis is a relatively new form of systemic amyloidosis, with beta2-microglobulin (B2M) being identified as the major constituent protein. Most of the clinical findings are related to amyloid deposition in osseo-articular tissues. B2M amyloid deposits first appear in the cervical intervertebral discs, which are well known to be susceptible to mechanical stress. A close relationship between changes of microenvironment caused by such stress and amyloid deposition is highly suggested. In advanced cases, an inflammatory reaction composed of macrophages, multinucleated giant cells, and granulation tissue, is observed around the amyloid deposits. Purified amyloid protein is native B2M, and mutations and proteolysis are not believed to be important for its deposition. Plasma levels of B2M are elevated as much as 5-10 times because of the inability of hemodialysis equipment removal of B2M from blood plasma, the duration being very important for B2M amyloid fibrillogenesis. Heparan sulfate proteoglycans, perlecan, is increased at the same sites of amyloid deposits from the early stages. In B2M amyloidosis, an increase of heparan sulfate proteoglycans is observed in the vascular wall and synovium, but in the discs, ligaments and cartilage, there is an increase of chondroitin sulfate proteoglycans predominantly. B2M has an affinity for heparan sulfate proteoglycans, although it is weaker than that for laminin and type IV collagen. This is related to the interactions between negative charges of sulfate groups of proteoglycans and positive charges of basic amino acids in N-terminal side of B2M. Increased cytokines production in the synovium, induced by advanced glycation end products as well as elevated plasma levels, is also linked to inflammatory reactions. Increased expression of matrix metalloproteinases (MMP), especially MMP-1 and -9, is related to the destructive changes of the bone and cartilage. The decrease of plasma levels by high flux membrane and control of inflammatory reactions are very important for prevention of B2M amyloidosis.

Amyloid↗

PubMed2001

Thiazolidinedione- and tumor necrosis factor alpha-induced downregulation of peroxisome proliferator-activated receptor gamma mRNA in differentiated 3T3-L1 adipocytes.

Thiazolidinediones (TZDs) are antidiabetic insulin-sensitizing agents that bind to peroxisome proliferator-activated receptor gamma (PPARgamma) and have potent adipogenic effects on 3T3-L1 preadipocytes. In fully differentiated 3T3-L1 adipocytes, TZDs markedly decreased PPARgamma mRNA levels without reducing the expression of genes that are positively regulated by PPARgamma, such as adipocyte lipid-binding protein 2 (aP2) or lipoprotein lipase-(LPL). PPARgamma mRNA levels were also downregulated by tumor necrosis factor alpha (TNFalpha), an antiadipogenic cytokine. We propose that the downregulation of PPARgamma is not the common denominator of the metabolic effects of TZDs and TNFalpha on mature adipocytes.

3T3 Cells↗

PubMed2001

Effect of genotypic differences in CYP2C19 on cure rates for Helicobacter pylori infection by triple therapy with a proton pump inhibitor, amoxicillin, and clarithromycin.

BACKGROUND: Proton pump inhibitors such as omeprazole and lansoprazole are mainly metabolized by CYP2C19 in the liver. The therapeutic effects of proton pump inhibitors are assumed to depend on CYP2C19 genotype status. OBJECTIVE: We investigated whether CYP2C19 genotype status was related to eradication rates of H pylori by triple proton pump inhibitor-clarithromycin-amoxicillin (INN, amoxicilline) therapy and attempted to establish a strategy for treatment after failure to eradicate H pylori. METHODS: A total of 261 patients infected with H pylori completed initial treatment with 20 mg of omeprazole or 30 mg of lansoprazole twice a day, 200 mg of clarithromycin three times a day, and 500 mg of amoxicillin three times a day for 1 week. CYP2C19 genotypes of patients were determined with polymerase chain reaction-restriction fragment length polymorphism analysis. Patients without eradication after initial treatment were retreated with 30 mg of lansoprazole four times daily and 500 mg of amoxicillin four times daily for 2 weeks. RESULTS: Eradication rates for H pylori were 72.7% (95% confidence interval, 64.4%-81.8%), 92.1% (confidence interval, 86.4%-97.3%), and 97.8% (confidence interval, 88.5%-99.9%) in the homozygous extensive, heterozygous extensive, and poor metabolizer groups, respectively. Thirty-four of 35 patients without eradication had an extensive metabolizer genotype of CYP2C19. Nineteen of those patients were infected with clarithromycin-resistant strains of H pylori. However, there were no amoxicillin-resistant strains of H pylori. Re-treatment of H pylori infection with dual high-dose lansoprazole-amoxicillin therapy succeeded in 30 of 31 patients with extensive metabolizer genotype of CYP2C19. CONCLUSION: The majority of patients without initial eradication of H pylori had an extensive metabolizer CYP2C19 genotype but were successfully re-treated with high doses of lansoprazole and an antibiotic to which H pylori was sensitive, such as amoxicillin, even when the patients were infected with clarithromycin-resistant strains of H pylori.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2001

Effect of high-dose lansoprazole on intragastic pH in subjects who are homozygous extensive metabolizers of cytochrome P4502C19.

BACKGROUNDS AND AIM: Lansoprazole is mainly metabolized by cytochrome P4502C19 (CYP2C19) in the liver. The effect of lansoprazole is assumed to be insufficient in subjects who are homozygous extensive metabolizers of CYP2C19. This study aimed to examine whether the CYP2C19 genotype status affected the acid-inhibitory effects of lansoprazole and to develop a strategy to overcome this pharmacogenetic problem. METHODS: Eighteen Helicobacter pylori-negative healthy volunteers, whose CYP2C19 genotypic status had been assessed, participated in the study. They consisted of 7 subjects who were homozygous extensive metabolizers, 7 subjects who were heterozygous extensive metabolizers, and 4 subjects who were poor metabolizers of CYP2C19, who took a placebo or lansoprazole 30 mg once daily in the morning for 8 days. On day 8 of dosing, 24-hour intragastric pH values were recorded. Five of the homozygous extensive metabolizer subjects underwent the 24-hour intragastric pH monitoring on day 8 of dosing of lansoprazole 30 mg 4 times daily. RESULTS: When lansoprazole 30 mg was given once daily, the mean 24-hour intragastric pH values in the subjects who were homozygous extensive metabolizers, heterozygous extensive metabolizers, and poor metabolizers were 4.5, 4.9, and 5.5, respectively (P <.005). On day 8 of dosing of lansoprazole 30 mg 4 times daily in subjects who were homozygous extensive metabolizers, the mean 24-hour intragastric pH value was 7.4. CONCLUSION: The effect of lansoprazole on intragastric pH depended significantly on CYP2C19 genotype status. Complete acid inhibition could be achieved by the frequent administration of lansoprazole (eg, 30 mg 4 times daily) in subjects who were homozygous extensive metabolizers. A genotyping test of CYP2C19 status appears useful for prescribing an optimal dosing scheme of lansoprazole.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2001

Immunohistological analysis of thymoma by molecules differentially expressed in the thymic cortex and medulla, and its application in the differential diagnosis of thymoma from esophageal and lung cancer.

The purpose of this study was to verify the WHO classification of thymic tumors using immunohistological methods, and to discover whether these methods can be applied to differentiate thymoma from squamous cell carcinoma (SCC) of the esophagus and the lung. Twenty-nine thymoma cases were classified according to WHO and were then immunohistologically examined for the positivity of these molecules. All thymoma cases investigated in this study were positive for IL-1R, and most of them were also positive for bek. In contrast, UH-1 was highly positive in B1 and B2 type thymomas, but negative or weakly positive in A, AB and B3 type thymomas. Twelve esophageal cancers and 21 lung cancers were also examined for the positivity of the same molecules. All esophageal cancers were negative for UH-1. Three of 12 cases were weakly positive for IL-1R, and four of these 12 cases were also weakly positive for bek. Twelve of 21 lung cancer cases were adenocarcinomas, all of them negative for IL-1R, bek and UH-1. Nine of 21 lung cancer cases were SCCs, all of them negative for UH-1. Eight of nine SCC cases were strongly positive for IL-1R, while seven of these were weakly positive for bek. We conclude that the WHO classification of thymic tumors is still valid as demonstrated by immunohistological analysis and that the positivity of UH-1, IL- 1R and bek might be helpful in differentiating thymoma from SCC of the esophagus and the lung.

Adenocarcinoma↗

PubMed2001

Expression of two subtypes of human IFN-alpha in transgenic potato plants.

Plant expression systems have advantages over other in vitro expression systems in terms of low production costs and low risk of contamination by animal viruses or bacterial endotoxins. In this study, cDNA encoding two subtypes of human interferon-alpha2b and 8 (HuIFN-alpha2b and HuIFN-alpha8) were introduced into potato plants (Solanum tuberosum) using Agrobacterium-mediated transformation. Transcription and translation of the inserted HuIFN-alpha cDNA were confirmed by Northern blot analysis and ELISA, respectively. Bioactivity of the products was assayed by inhibition of vesicular stomatitis virus (VSV) replication on a human amniotic cell line. However, because of the presence of substances in potato tissue extracts that were toxic to animal cells, successful demonstration of IFN bioactivity in the transformants was achieved only after removal of such substances by dialysis. The maximum level of IFN activity in plant extracts was 560 IU/g of tissue. These results indicated that the HuIFN-alpha gene introduced into the potato plant was correctly translated and transcribed in plant cells. This report for the first time shows that biologically active animal cytokines with potential pharmaceutical applications could be expressed in transgenic potato plants.

Antiviral Agents↗

PubMed2001

Insulin inhibits coronary endothelial cell calcium entry and coronary artery relaxation.

Hyperinsulinemia is closely related to coronary artery disease. Endothelial cells are important for the control of vascular tone, and dysfunction of endothelial cells has been implicated in coronary artery disease. The direct effects of insulin on coronary endothelial cells are nonetheless unknown. In this study, the acute effects of high-dose insulin were investigated on agonist-induced intracellular Ca(2+) concentration ([Ca(2+)](i)) in porcine coronary endothelial cells and coronary relaxation. Bradykinin (10 n M ) and cyclopiazonic acid (100 microM), an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, provoked large increases in [Ca(2+)](i) in coronary endothelial cells. This increase was dose-dependently inhibited by a 10-min preincubation with high doses of insulin (10, 30, 100 mU/ml). Under Ca(2+)-free conditions, bradykinin and cyclopiazonic acid provoked transient, small increases in [Ca(2+)](i). These increases were not affected by pretreatment with insulin (100 mU/ml). Bradykinin (1, 10, 100, 1,000 n M ) and cyclopiazonic acid (10 microM) significantly relaxed porcine coronary artery rings precontracted with histamine (1 microM). The vasodilator effects of bradykinin and cyclopiazonic acid were dose-dependently inhibited by insulin. These acute effects were not observed at physiologic concentrations. Our data indicate that high-dose insulin inhibits agonist-induced Ca(2+) response in coronary endothelial cells and attenuates agonist-induced coronary vasodilatation. The study suggests that hyperinsulinemia might be associated with coronary artery disease via derangement of endothelial Ca(2+)-dependent functions.

Animals↗

PubMed2001

Effects of genotypic differences in CYP2C19 status on cure rates for Helicobacter pylori infection by dual therapy with rabeprazole plus amoxicillin.

Rabeprazole is a potent proton pump inhibitor and is mainly reduced to thioether rabeprazole by a non-enzymatic pathway and partially metabolized to demethylated rabeprazole by CYP2C19 in the liver. We intended to determine a cure rate for Helicobacter pylori infection by dual rabeprazole/amoxicillin therapy in relation to CYP2C19 genotype status prospectively. Ninety-seven patients with gastritis and H. pylori infection completed the dual therapy with 10 mg of rabeprazole bid and 500 mg of amoxicillin tid for 2 weeks. At 1 month after treatment, cure of H. pylori infection was assessed on the basis of histology, a rapid urease test, culture, polymerase chain reaction (PCR), and 13C-urea breath test. CYP2C19 genotype status was determined by a PCR-restriction fragment length polymorphism method. Of the 97 patients, 33 were homozygous extensive metabolizers (homEM), 48 were heterozygous extensive metabolizers (hetEM), and 16 were poor metabolizers (PM). Cure of H. pylori infection was achieved in 79 of the 97 patients (81.4%, 95%CI = 71.9-88.7). Significant differences in cure rates among the homEM, hetEM, and PM groups were observed; 60.6% (95%CI = 42.1-77.3), 91.7% (95%CI = 80.0-97.7), and 93.8% (95%CI = 69.8-99.8), respectively (P = 0.0007). Twelve patients without cure after initial treatment (10 homEMs and 2 hetEMs) were successfully retreated with rabeprazole 10 mg q.i.d. and amoxicillin 500 mg q.i.d. for 2 weeks. The cure rates for H. pylori infection by dual rabeprazole/amoxicillin therapy depended on the CYP2C19 genotype status. This dual therapy appears to be effective for hetEM and PM patients. However, high dose dual rabeprazole/amoxicillin therapy was effective even for homEM patients. Therefore, the genotyping test of CYP2C19 appears to be a clinically useful tool for the optimal dual treatment with rabeprazole plus amoxicillin.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2001

Loss of syndecan-1 and increased expression of heparanase in invasive esophageal carcinomas.

Heparan sulfate proteoglycans play important biological roles in cell-cell and cell-matrix adhesion, and are closely associated with growth factor actions. Loss of syndecan-1, a cell surface-bound heparan sulfate proteoglycan, has been reported for advanced head and neck carcinomas, and expression of endoglycosidic heparanase, which cleaves heparan sulfate glycosaminoglycans (HS-GAGs), is associated with invasion and metastatic potential of malignant tumors. Paraffin sections of 103 primary esophageal squamous cell carcinomas were immunohistochemically examined for the expression of syndecan-1 core protein, HS-GAGs and heparanase protein, and the results were compared with various clinicopathological parameters, such as invasion depth. For 16 cases, fresh tumor samples were quantitatively analyzed for heparanase and syndecan-1 mRNA expression by real-time RT-PCR in addition to the immunohistochemical studies. Syndecan-1 core protein and HS-GAGs expression was significantly decreased in pT2 and pT3 cases compared with their pTis and pT1 counterparts. Decreased expression of core protein and HS-GAGs was correlated with the incidence of lymphatic invasion, and venous involvement. Furthermore, decreased expression of HS-GAGs was correlated positively with the incidence of nodal metastasis and distant organ metastasis, and negatively with the grade of tumor cell differentiation. The percentage of cytoplasmic heparanase protein-positive cases increased significantly in pT2 and pT3 cases compared to that in pTis and pT1 cases, and this was associated with lymphatic invasion, and venous and lymph nodal involvement. The level of heparanase mRNA was inversely correlated with the degree of HS-GAGs expression rather than core protein. In conclusion, loss of syndecan-1 and heparanase overexpression in esophageal squamous cell carcinomas are closely associated with malignant potential. Regarding the mechanism of loss of HS-GAGs, heparanase upregulation appears to play an important role.

Adult↗

PubMed2001

Identification of liver X receptor-retinoid X receptor as an activator of the sterol regulatory element-binding protein 1c gene promoter.

In an attempt to identify transcription factors which activate sterol-regulatory element-binding protein 1c (SREBP-1c) transcription, we screened an expression cDNA library from adipose tissue of SREBP-1 knockout mice using a reporter gene containing the 2.6-kb mouse SREBP-1 gene promoter. We cloned and identified the oxysterol receptors liver X receptor (LXRalpha) and LXRbeta as strong activators of the mouse SREBP-1c promoter. In the transfection studies, expression of either LXRalpha or -beta activated the SREBP-1c promoter-luciferase gene in a dose-dependent manner. Deletion and mutation studies, as well as gel mobility shift assays, located an LXR response element complex consisting of two new LXR-binding motifs which showed high similarity to an LXR response element recently found in the ABC1 gene promoter, a reverse cholesterol transporter. Addition of an LXR ligand, 22(R)-hydroxycholesterol, increased the promoter activity. Coexpression of retinoid X receptor (RXR), a heterodimeric partner, and its ligand 9-cis-retinoic acid also synergistically activated the SREBP-1c promoter. In HepG2 cells, SREBP-1c mRNA and precursor protein levels were induced by treatment with 22(R)-hydroxycholesterol and 9-cis-retinoic acid, confirming that endogenous LXR-RXR activation can induce endogenous SREBP-1c expression. The activation of SREBP-1c by LXR is associated with a slight increase in nuclear SREBP-1c, resulting in activation of the gene for fatty acid synthase, one of its downstream genes, as measured by the luciferase assay. These data demonstrate that LXR-RXR can modify the expression of genes for lipogenic enzymes by regulating SREBP-1c expression, providing a novel link between fatty acid and cholesterol metabolism.

Alitretinoin↗