Highly efficient titanosilicate catalyst Ti-MCM-68 prepared using a liquid-phase titanium source for the phenol oxidation

A highly efficient Ti-MCM-68 catalyst for phenol oxidation with H₂O₂ was prepared by a mild liquid-phase treatment for the first time. The key preparation procedures to excellent catalytic activity and high para-selectivity were the use of aqueous solutions of the Ti source and calcination at 650 °C prior to catalytic use.

A highly efficient Ti-MCM-68 catalyst for phenol oxidation with H₂O₂ was prepared by a mild liquid-phase treatment for the first time.

The ectonucleotidases alkaline phosphatase and nucleoside triphosphate diphosphohydrolase 2 are associated with subsets of progenitor cell populations in the mouse embryonic, postnatal and adult neurogenic zones

Subventricular zone (SVZ)-derived adult neurospheres express two ectonucleotidases, nucleoside triphosphate diphosphohydrolase 2 (NTPDase2) and tissue non-specific alkaline phosphatase (TNAP). Agonists of the nucleotide receptors P2Y(1) and P2Y(2) as well as adenosine augment growth factor-mediated progenitor cell proliferation. NTPDase2 converts ATP and UTP to ADP and UDP, respectively, which are all P2Y receptor agonists. TNAP hydrolyzes nucleoside triphosphates and diphosphates and produces the P1 receptor agonist adenosine. In the SVZ, NTPDase2 is specifically expressed by type B cells. In order to further scrutinize the association of key molecules of the purinergic signaling pathway with neurogenic regions, we analyzed the expression of TNAP at the lateral ventricles of the adult and developing mouse brain. In the adult brain, TNAP was expressed by type B, type A and at least subsets of type C cells of the SVZ and throughout the rostral migratory stream. Almost 100% of the proliferating, Ki-67-positive cells of the adult SVZ stained for TNAP, supporting the notion of a ubiquitous association of TNAP with SVZ progenitors. In contrast, NTPDase2-positive progenitors of the dentate gyrus were TNAP-negative. Essentially all cells of the telencephalic vesicle at embryonic day (E) 14 revealed TNAP activity, including doublecortin-positive neuroblasts. During further embryonic development, enhanced TNAP activity became restricted to cells of the ventricular and SVZ. In contrast to TNAP, NTPDase2 was first expressed in the SVZ perinatally, in association with TNAP-positive SVZ border cells. During later development, NTPDase2-positive cells disappeared from the ventricular surface and began to form sheaths around clusters of subventricular doublecortin-positive cells, apparently transforming into type B cells. Our results identify TNAP and NTPDase2 as novel markers for subsets of progenitors in the adult and developing mouse brain. They further support the notion that signaling via extracellular nucleotides and nucleosides contributes to embryonic and adult neurogenesis.

Molecular basis for sensitivity and acquired resistance to gefitinib in HER2-overexpressing human gastric cancer cell lines derived from liver metastasis

Gastric cancer metastasised to the liver was found to overexpress HER2 at a significantly higher incidence than primary gastric cancers. The purpose of the present study was to investigate the possibility of molecular therapy targeting HER2 overexpression in gastric cancer liver metastasis. We developed three new HER2-overexpressing gastric cancer cell lines (GLM-1, GLM-2, GLM-4) without epidermal growth factor receptor (EGFR) mutations derived from such liver metastasis, two of which had HER2 gene amplifications. All these GLM series of cell lines were highly sensitive to gefitinib in vitro, a specific inhibitor of EGFR tyrosine kinase (Iressa) rather than anti-HER2 antibody trastuzumab (Herceptin), whereas most of the HER2 low-expressing counterparts were not. In these HER2-overexpressing GLM series, protein kinase B (Akt), but not extracellular signal-regulated kinase 1/2 (ERK1/2), was constitutively phosphorylated, and gefitinib efficiently inhibited this Akt phosphorylation, induced strong apoptosis in vitro and exhibited antitumour activity in tumour xenografts in nude mice. This gefitinib-mediated antitumour effect in xenograft was significantly potentiated by trastuzumab treatment. On the other hand, gefitinib-resistant cells (GLM-1R) exhibited increased EGFR expression, followed by constitutive activation of mitogen-activated protein kinase (MAPK) pathway. These results suggest that the antitumour effect of gefitinib is due to the effective inhibition of HER2-driven constitutive activation of phosphatidylinositol-3-kinase (PI3K)/Akt pathway, and that the acquired resistance to gefitinib is due to the constitutive activation of Ras/MAPK pathway in compensation for PI3K/Akt pathway. Gastric cancer liver metastasis with HER2 overexpression would be a potential molecular target for gefitinib and trastuzumab.

Smoking and polymorphisms of fucosyltransferase gene Le affect success of H. pylori eradication with lansoprazole, amoxicillin, and clarithromycin

Identification of factors influencing success of Helicobacter pylori (HP) eradication is important for clinical practice. We have prospectively conducted an HP eradication study in the Aichi Cancer Center with a total of 142 patients available for analysis. The overall success rate was 61.3% (95% confidence interval 52.7-69.3%). Smoking during the medication for eradication significantly decreased the success rate (42.9%), whereas smoking cessation during the treatment was associated with a similar rate as for non-smokers (66.7%). We also examined links between an eradication outcome and polymorphisms of Le, Se, IL1A, IL1B, IL1RN and MPO genes, but with one exception none showed any association. The non-functional le allele of Le polymorphisms, leading to decreased expression of Le(b) antigen to which HP attaches with adhesin, showed a beneficial effect for success. Although further clarification is necessary, our study indicated that smoking cessation and Le gene polymorphisms may affect the success rate of HP eradication.

An active-site mutation (Gly633 .fwdarw. Arg) of dipeptidyl peptidase IV causes its retention and rapid degradation in the endoplasmic reticulum

Dipeptidyl peptidase IV (DPPIV), a serine protease expressed on the cell surface, is deficient in a Fischer rat substrain. Northern blot analysis showed no difference in the size and amount of DPPIV mRNA between normal (344/NC) and deficient (344/CRJ) rats. Cloning and sequencing of DPPIV cDNAs revealed a G to A transition at nucleotide 1897 in the cDNA sequence of 344/CRJ, which leads to substitution of Gly633-->Arg in the active-site sequence Gly629-Trp-Ser-Tyr-Gly633 determined for the wild-type DPPIV [Ogata, S., Misumi, Y., Takami, N., Oda, K., & Ikehara, Y. (1992) Biochemistry 31, 2582-2587]. Pulse-chase experiments with hepatocytes showed that the wild-type DPPIV was initially synthesized as a 103-kDa form with high-mannose-type oligosaccharides, which was processed to a mature form of 109 kDa with the complex type during intracellular transport. In contrast, the mutant DPPIV, although being synthesized as the 103-kDa form, was rapidly degraded without being processed to the mature form. Site-directed mutagenesis of the wild-type and mutant cDNAs and their transfection/expression in COS-1 cells confirmed that the single substitution of Gly633-->Arg is sufficient to cause the rapid intracellular degradation of DPPIV. Immunoelectron-microscopic observations showed that the mutant DPPIV was detectable only in the endoplasmic reticulum (ER), in contrast to the distribution of the wild-type DPPIV in the Golgi complex and on the cell surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of the active site residues in dipeptidyl peptidase IV by affinity labeling and site-directed mutagenesis

The active site of dipeptidyl peptidase IV (DPPIV) was examined by chemical modification and site-directed mutagenesis. Purified DPPIV was covalently modified with [3H]diisopropyl fluorophosphate (DFP). The radiolabeled DPPIV was digested with lysyl endopeptidase, and the peptides were separated by high-performance liquid chromatography. A single 3H-containing peptide was obtained and analyzed for amino acid sequence and radioactivity distribution. A comparison of the determined sequence with the predicted primary structure of DPPIV [Ogata, S., Misumi, Y., & Ikehara, Y. (1989) J. Biol. Chem. 264, 3596-3601] revealed that [3H]DFP was bound to Ser631 within the sequence Gly629-Trp-Ser-Tyr-Gly633, which corresponds to the consensus sequence Gly-X-Ser-X-Gly proposed for serine proteases. To further identify the essential residues in the active-site sequence, we modified the DPPIV cDNA by site-directed mutagenesis to encode its variants. Expression of the mutagenized cDNAs in COS-1 cells demonstrated that any single substitution of Gly629, Ser631, or Gly633 with other residues resulted in the complete loss of the enzyme activity and DFP binding. Although substitution of Trp630----Glu or Tyr632----Phe caused no effect on the enzyme activity, that of Tyr632----Leu or Gly abolished the activity. These results indicate that the sequence Gly-X-Ser-(Tyr)-Gly is essential for the expression of the DPPIV activity.

The GM130 and GRASP65 Golgi proteins cycle through and define a subdomain of the intermediate compartment

Integrating the pleomorphic membranes of the intermediate compartment (IC) into the array of Golgi cisternae is a crucial step in membrane transport, but it is poorly understood. To gain insight into this step, we investigated the dynamics by which cis-Golgi matrix proteins such as GM130 and GRASP65 associate with, and incorporate, incoming IC elements. We found that GM130 and GRASP65 cycle via membranous tubules between the Golgi complex and a constellation of mobile structures that we call late IC stations. These stations are intermediate between the IC and the cis-Golgi in terms of composition, and they receive cargo from earlier IC elements and deliver it to the Golgi complex. Late IC elements are transient in nature and sensitive to fixatives; they are seen in only a fraction of fixed cells, whereas they are always visible in living cells. Finally, late IC stations undergo homotypic fusion and establish tubular connections between themselves and the Golgi. Overall, these features indicate that late IC stations mediate the transition between IC elements and the cis-Golgi face.

Identification and characterization of a novel Golgi protein, GCP60, that interacts with the integral membrane protein giantin

We demonstrated previously that the integral membrane protein giantin has the Golgi localization signal at the COOH-terminal cytoplasmic domain (Misumi, Y., Sohda, M., Tashiro, A., Sato, H., and Ikehara, Y. (2001) J. Biol. Chem. 276, 6867-6873). In the present study, using this domain as bait in the yeast two-hybrid screening system, we identified a novel protein interacting with giantin. The 3.6-kilobase mRNA encoding a 528-amino acid protein of 60 kDa designated GCP60 was ubiquitously expressed and was especially abundant in the testis and ovary. Immunofluorescence and immunoelectron microscopy confirmed that GCP60 was co-localized with giantin in the Golgi complex. GCP60 was found to be a peripheral protein associated with the Golgi membrane, where a COOH-terminal domain of GCP60 interacts with the COOH-terminal cytoplasmic domain of giantin. Overexpression of the COOH-terminal domain of GCP60 caused disassembly of the Golgi structure and blocked protein transport from the endoplasmic reticulum to the Golgi. Taken together, these results suggest that GCP60 is involved in the maintenance of the Golgi structure by interacting with giantin, affecting protein transport between the endoplasmic reticulum and the Golgi.

Direct targeting of cis-Golgi matrix proteins to the Golgi apparatus

The targeting route of newly synthesized GM130 and GRASP65 to the Golgi apparatus was investigated by three different approaches. First, localization of pulse labeled GM130 and GRASP65 in normal rat kidney (NRK) cells was traced by subcellular fractionation followed by immunoprecipitation. Immediately after the pulse labeling, GM130 and GRASP65 were found in the Golgi but not in the endoplasmic reticulum (ER) membrane fractions, whereas a control Golgi membrane protein was still found in the ER membrane fractions. Second, epitope tagged GM130 and GRASP65 were expressed in NRK cells by plasmid microinjection into the nuclei and their localization was analyzed by immunofluorescence. When ER to Golgi transport was inhibited by prior microinjection of a GTP-restricted mutant of Sar1 protein into the cytosol, the expressed GM130 and GRASP65 showed clear Golgi localization. Last, binding of GM130 and GRASP65 to the membranes was analyzed in vitro. In vitro synthesized GM130 and GRASP65 specifically bound to purified Golgi membranes but not to microsomal membranes. The bound GM130 and GRASP65 were found to form a complex with pre-existing counterparts on the Golgi membrane. These results strongly suggested that GM130 and GRASP65 are directly targeted to the Golgi membrane without initial assembly on the ER and subsequent vesicular transport to the Golgi apparatus.

Role of furin in delivery of a CTL epitope of an anthrax toxin-fusion protein

Anthrax toxin lethal factor (LF) in combination with anthrax toxin protective antigen (PA) was endocytosed and translocated to the cytosol of mammalian cells. Residues 1-255 of anthrax toxin lethal factor (LFn) was fused to a cytotoxic T lymphocyte (CTL) epitope of an influenza virus. For processing the toxins, PA must be cleaved into a 63-kDa fragment (PA63) by furin, which is a subtilisin-like processing endo-protease expressed by many eukaryotic cells. To test the ability of cells treated with the LFn fusion protein plus PA to deliver the epitope, CTL assay was performed. Two types of cell lines were identified, one was able to deliver CTL epitope while the other failed to efficiently deliver the epitope. To further elucidate the differences between these cells, the role of furin in these cells was examined. Disruption of the furin gene reduced its ability to deliver the CTL epitope. Furin expression in cells capable of efficiently delivering CTL epitope was quantitatively higher than in cells unable to deliver the epitope. The results suggest that furin plays a critical role in delivery of the CTL epitope of LFn fusion protein.

Polymorphisms of two fucosyltransferase genes (Lewis and Secretor genes) involving type I Lewis antigens are associated with the presence of anti-Helicobacter pylori IgG antibody

Helicobacter pylori attach to the gastric mucosa with adhesin, which binds to Lewis b (Le(b)) or H type I carbohydrate structures. The Secretor (Se) gene and Lewis (Le) gene are involved in type I Le antigen synthesis. The present study was performed to investigate the possibility that Se and Le gene polymorphisms alter the risk of H. pylori infection. Two hundred thirty-nine participants were genotyped for Se and Le and tested for the presence of anti-H. pylori IgG antibodies. Using the normal gastric mucosa from 60 gastric cancer patients, we assessed immunohistochemically whether type I Le antigen expression depended on the Se and Le genotypes. The H. pylori infection rate was positively associated with the number of Se alleles (se/se group, 45.1%; Se/se group, 64.6%; and Se/Se group, 73.3%) and negatively associated with the number of Le alleles (le/le group, 76.4%; Le/le group, 68.3%; and Le/Le group, 55.6%). When the subjects were classified into three groups [low risk, (se/se, Le/Le) genotype; high risk, (Se/Se, le/le), (Se/Se, Le/le), and (Se/se, le/le) genotypes; moderate risk, other than low- or high-risk group], the odds ratio relative to the low-risk group was 3.30 (95% confidence interval, 1.40-7.78) for the moderate-risk group and 10.33 (95% confidence interval, 3.16-33.8) for the high-risk group. Immunohistochemical analysis supported the finding that Se and Le genotypes affected the expression of H. pylori adhesin ligands. We conclude that Se and Le genotypes affect susceptibility to H. pylori infection.

Real-time observation of micrometastasis formation in the living mouse liver using a green fluorescent protein gene-tagged rat tongue carcinoma cell line

Initial arrest, attachment, extravasation and subsequent extravascular growth of tumor cells in the secondary organs are believed to be crucial events for hematogenous metastasis, but the actual processes in living animals remain unclear. For the present study, we established green fluorescent protein (GFP)-expressing rat tongue carcinoma cell lines (RSC3) that permit real-time analysis of micrometastasis formation in combination with intravital video microscopy (IVVM). With this system, GFP-expressing metastatic (LM-EGFP) and non-metastatic (E2-EGFP) cell lines could be visualized at the cellular level in live mice for more than 1 month. Real-time IVVM analysis of liver metastases after intraportal injection of cells via a mesenteric vein revealed that both LM-EGFP and E2-EGFP tumor cells arrest similarly in sinusoidal vessels near terminal portal venules within 0.4 sec, during which time no evidence of a "rolling"-like movement along endothelial cell surfaces was observed. Quantitative analysis of GFP-positive foci showed that E2-EGFP cells were completely sheared from the liver sinusoid within 3 days, with no solitary dormant cells, whereas a substantial number of LM-EGFP cells remained in the liver, probably due to stable attachment to the sinusoidal wall. Confocal laser scanning microscopic study in combination with laminin immunohistochemistry revealed that only LM-EGFP cells started growth at 3 to 4 days after inoculation and that most of the growing foci were surrounded by subsinusoidal basement membrane. Our results suggest that micrometastasis formation by LM-EGFP cells consists of initial tumor cell arrest due to size constraints of the vessel, stable attachment to subsinusoidal basement membrane and subsequent intravascular growth before extravasation. The difference in metastatic potential between the 2 lines may reside in their capacity to attach stably to the vessel wall rather than their potential for initial cell arrest or subsequent growth. The system used in the present study may be a powerful tool for analyzing targets for various anti-metastatic agents in the sequential process of metastasis.

Inhibition by Agaricus blazei Murill fractions of cytopathic effect induced by western equine encephalitis (WEE) virus on VERO cells in vitro

Anti-viral activities of Agaricus blazei Murill were investigated. The water extracts of the cultured mycelia and fruiting bodies were fractionated with different concentrations of ethanol. To several viruses which have cytopathic effects (CPE) on VERO cells, inhibition of these effects by the ethanol fractions was tested. Strong inhibition of CPE induced by western equine encephalitis (WEE) virus was observed in the mycelial fractions but not those of fruiting bodies.

Identification of Paneth cells in pyloric glands associated with gastric and intestinal mixed-type intestinal metaplasia of the human stomach

We have proposed that intestinal metaplasia (IM) of the human stomach be divided into two types on the basis of cell differentiation status: a gastric and intestinal (GI) mixed type and a solely intestinal (I) type. In the GI mixed type, gastric (foveolar epithelial and pyloric gland cells) and intestinal (goblet, intestinal absorptive, and Paneth cells) phenotype cells coexist in the same intestinalized gastric glands in various combinations and degrees. Consequently, intestinalized gastric glands are hybrids. Although we have described the rare appearance of Paneth-like cells in pyloric glands of GI mixed-type IM, the absence of an appropriate Paneth cell marker leaves room for doubt as to their true character. The purpose of this study was to clearly identify Paneth cells in pyloric glands in IM lesions using a new Paneth cell marker, a polyclonal antibody human defensin (HD)-5, raised against HD-5, which is included in granules of Paneth cells. A total of 105 gastric samples (4 biopsy and 101 surgical resected specimens) were examined. In only nine cases (8.6%), the antibody allowed demonstration of Paneth cells in pyloric glands in GI mixed-type IM, confirming our previous finding. Analysis of the proliferative cell (P) zone indicated that a common stem cell might generate both GI phenotype cells by upward and downward migration. No Paneth cells were found above the P zone. The results suggest that the stem cells show abnormal cell differentiation in IM lesions but preserve their normal direction of migration.

Secretion of TNF-alpha, IL-8 and nitric oxide by macrophages activated with Agaricus blazei Murill fractions in vitro

Water extracts of the mycelial culture and fruiting bodies of Agaricus blazei Murill were fractionated by ethanol precipitation using various ethanol concentrations. Original water extracts from mycelia (Fraction A-0) and fruiting bodies (Fraction B-0) induced TNF-alpha secretion by macrophages derived from rat bone marrow. Fractions B-4 and B-5 obtained from ethanol precipitation of fruiting bodies using 44% and 50% ethanol, respectively, and Fraction B-6 obtained from the supernatant at 50% ethanol markedly induced TNF-alpha secretion. Similar effects were observed in IL-8 secretion by macrophages. Regarding nitric oxide (NO), Fraction B-5 induced a significant increase in NO secretion and Fractions B-4 and B-6 induced slightly NO secretion. Northern blot analysis showed that the increases in cytokine- and NO secretion were due to an increase in cytokine mRNAs or NO synthase mRNA. Therefore, it is concluded that Agaricus blazei Murill components which activate macrophages result in the induction of cytokine- and NO secretion in vitro.

An essential cytoplasmic domain for the Golgi localization of coiled-coil proteins with a COOH-terminal membrane anchor

Giantin is a resident Golgi protein that has an extremely long cytoplasmic domain (about 370 kDa) and is anchored to the Golgi membrane by the COOH-terminal membrane-anchoring domain (CMD) with no luminal extension. We examined the essential domain of giantin required for Golgi localization by mutational analysis. The Golgi localization of giantin was not affected by the deletion of its CMD or by substitution with the CMD of syntaxin-2, a plasma membrane protein. The giantin CMD fused to the cytoplasmic domain of syntaxin-2 could not retain the chimera in the Golgi apparatus. Sequential deletion analysis showed that the COOH-terminal sequence (positions 3059--3161) adjacent to the CMD was the essential domain required for the Golgi localization of giantin. We also examined two other Golgi-resident proteins, golgin-84 and syntaxin-5, with a similar membrane topology as giantin. It was confirmed that the cytoplasmic domain of about 100 residues adjacent to the CMD was required for their Golgi localization. Taken together, these results suggest that the COOH-terminally anchored Golgi proteins with long cytoplasmic extensions have the Golgi localization signal(s) in the cytoplasmic sequence adjacent to the CMD. This is in contrast to previous observations that a transmembrane domain is required for Golgi localization by other Golgi proteins transported from the endoplasmic reticulum.

Biosynthesis and characterization of the brain-specific membrane protein DPPX, a dipeptidyl peptidase IV-related protein

Dipeptidyl peptidase IV-related protein (DPPX) was found to be preferentially expressed in the brain tissue. We isolated two rat cDNA clones encoding DPPX-S and DPPX-L from a brain cDNA library, of which DPPX-L had a longer sequence at the NH2 terminus. The biosynthesis of DPPXs was examined in both in vitro and in vivo systems. In the cell-free translation system, DPPX-S and DPPX-L were synthesized as 93-kDa and 97-kDa forms, respectively, which are in good agreement with the molecular masses estimated from their primary structure. In COS-1 cells transfected with the cDNAs, DPPX-S and DPPX-L were initially synthesized as 113-kDa and 117-kDa forms, respectively, with high-mannose type oligosaccharides, which were then converted to 115-kDa and 120-kDa forms, mostly with the complex-type sugar chains. Immunofluorescence-microscopic observations confirmed that both DPPXs were expressed on the cell surface. DPPXs were found to have no enzyme activity of DPPIV, even when they were mutated to have the consensus active-site sequence Gly-X-Ser-X-Gly for serine proteases. Immunoblot analysis of samples prepared from various rat tissues demonstrated that DPPX-S, but not DPPX-L, was detectable only in the brain tissue. These results indicate that, of the two isoforms, DPPX-S is preferentially expressed in the brain tissue as the surface glycoprotein without protease activity, although its function remains unknown at present.

[Congenital rubella syndrome developing after a 1987-1988 epidemic in Japan]

Since vaccination legislation was revised in 1994, rubella vaccination has been changed from application to all junior high school girls with no history of clinical rubella to application to individual infants and junior high school students. This may decrease the vaccination acceptance rate and increase the chance of pregnant women's infection with rubella causing congenital rubella syndrome (CRS). We studied 5 children with CRS developed after a 1987-1988 epidemic in Japan to determine how their mothers were infected, and reviewed auditory findings. They were CRS-confirmed or CRS-compatible cases who met CRS diagnostic criteria formulated by the U.S. Center for Disease Control (CDC) in 1983. Two mothers had not been vaccinated because this was not legislated when they were in junior high school. Three were eligible for vaccination at 14, but 2 were not vaccinated. The children were born in 1991-1997. Complications were low birth weight in 3, delay in neck stabilization in 2, and cataract in 1. No case was serious. Ages at first ENT examination ranged from 3 months to 1 year and 8 months. ABR showed hearing loss of > or = 90 dBnHL. They started using hearing aids at 6 months to 1 year and 10 months. Tsumori mental development tests showed delays in developmental age in 2 who started auditory training after ages of 1 year and 6 months. Findings indicated that infants, students, and potentially pregnant women should be vaccinated. Complete serologic testing are important in pregnant women and fetal rubella infection should be diagnosed early by PCR.

Prolongation of rat islet xenograft survival in the liver of IFN-gamma-deficient mice

The cellular mechanisms involved in islet xenograft rejection remain undetermined. In the present study, the role of interferon-gamma (IFN-gamma) in rat islet xenograft rejection was examined with the use of IFN-gamma-deficient mice as recipients and the results were compared with allografts. There was no significant difference in the survival of intrahepatic islet allografts in IFN-gamma-deficient mice compared with that in wild-type mice. In contrast, a marked prolongation of rat islet xenograft survival was obtained in IFN-gamma-deficient mice without immunosuppression when compared with the survival in wild-type mice. In order to dissect the difference, infiltrating cells in the liver in association with rejection were examined with flow cytometry. An expansion of CD8 T cells was seen in the liver of wild-type mice rejecting xenografts compared with isografts. There was no significant change in other cell populations. In IFN-gamma-deficient mice, the expansion of CD8 T cells was seen in the liver rejecting xenografts; however, the time of development was markedly delayed by the time of rejection. These findings suggest that the acute rejection of rat islet xenografts in mice is IFN-gamma-dependent although the exact mechanisms remain unknown.

Possible interference between tissue-non-specific alkaline phosphatase with an Arg54-->Cys substitution and acounterpart with an Asp277-->Ala substitution found in a compound heterozygote associated with severe hypophosphatasia

Tissue-non-specific alkaline phosphatase (TNSALP) with an Arg(54)-->Cys (R54C) or an Asp(277)-->Ala (D277A)substitution was found in a patient with hypophosphatasia [Henthorn,Raducha, Fedde, Lafferty and Whyte (1992) Proc. Natl. Acad. Sci. U.S.A.89, 9924-9928]. To examine effects of these missense mutations onproperties of TNSALP, the TNSALP mutants were expressed ectopically inCOS-1 cells. The wild-type TNSALP was synthesized as a 66-kDa endo-beta-N-acetylglucosaminidase H (Endo H)-sensitive form, and processed to an 80-kDa mature form, which is anchored to the plasma membrane via glycosylphosphatidylinositol (GPI). Although the mutant proteins were found to be modified by GPI, digestion with phosphatidylinositol-specific phospholipase C, cell-surface biotinylation and immunofluorescence observation demonstrated that the cell-surface appearance of TNSALP (R54C) and TNSALP (D277A) was either almost totally or partially retarded respectively. The 66-kDa Endo H-sensitive band was the only form, and was rapidly degraded in the cells expressing TNSALP (R54C). In contrast with cells expressing TNSALP(R54C), where alkaline phosphatase activity was negligible, significant enzyme activity was detected and, furthermore, the 80-kDa mature form appeared on the surface of the cells expressing TNSALP (D277A). Analysis by sedimentation on sucrose gradients showed that a considerable fraction of newly synthesized TNSALP (R54C) and TNSALP(D277A) formed large aggregates, indicating improper folding and incorrect oligomerization of the mutant enzymes. When co-expressed with TNSALP (R54C), the level of the 80-kDa mature form of TNSALP (D277A)was decreased dramatically, with a concomitant reduction in enzyme activity in the co-transfected cell. These findings suggest that TNSALP(R54C) interferes with folding and assembly of TNSALP (D277A) intrans when expressed in the same cell, thus probably explaining why a compound heterozygote for these mutant alleles developed severe hypophosphatasia.

CD4(+) Valpha14 natural killer T cells are essential for acceptance of rat islet xenografts in mice

Pancreatic islet transplantation represents a potential treatment for insulin-dependent diabetes mellitus. However, the precise cellular and molecular mechanisms of the immune reactions against allogeneic and xenogeneic transplanted islets remain unclear. Here, we demonstrate that CD4(+) Valpha14 natural killer T (NKT) cells, a recently identified lymphoid cell lineage, are required for the acceptance of intrahepatic rat islet xenografts. An anti-CD4 mAb, administrated after transplantation, allowed islet xenografts to be accepted by C57BL/6 mice, with no need for immunosuppressive drugs. The dose of anti-CD4 mAb was critical, and the beneficial effect appeared to be associated with the reappearance of CD4(+) NKT cells at around 14 days after transplantation. Interestingly, rat islet xenografts were rejected, despite the anti-CD4 mAb treatment, in Valpha14 NKT cell-deficient mice, which exhibit the normal complement of conventional lymphoid cells; adoptive transfer of Valpha14 NKT cells into Valpha14 NKT cell-deficient mice restored the acceptance of rat islet xenografts. In addition, rat islet xenografts were accepted by Valpha14 NKT mice having only Valpha14 NKT cells and no other lymphoid cells. These results indicate that Valpha14 NKT cells play a crucial role in the acceptance of rat islet xenografts in mice treated with anti-CD4 antibody, probably by serving as immunosuppressive regulatory cells.

Molecular cloning and genomic analysis of mouse GalNAc alpha2, 6-sialyltransferase (ST6GalNAc I)

cDNA clones encoding mouse GalNAc alpha2,6-sialyltransferase (ST6GalNAc I) were isolated from a mouse submaxillary gland cDNA library. The deduced amino acid sequence of cDNA clones is 526 amino acids in length and has highly conserved motifs among sialyl transferases, sialyl motifs L, S, and VS. The expressed recombinant enzyme exhibited similar substrate specificity to chicken ST6GalNAc I. The mouse ST6GalNAc I gene was expressed in submaxillary gland, mammary gland, colon, and spleen. The mouse ST6GalNAc I gene was also cloned from a mouse genomic library, which was divided into 9 exons spanning over 8 kilobases of genomic DNA. The genomic structure of the mouse ST6GalNAc I gene was similar to that of the mouse ST6GalNAc II gene. Unlike the ST6GalNAc II gene, however, which has a housekeeping gene-like promoter with GC-rich sequences, the ST6GalNAc I gene has two promoters and they do not contain GC-rich sequences but contain putative binding sites for tumor-associated transcription factors such as c-Myb, c-Myc/Max, and c-Ets. Analysis of the 5'-RACE PCR products suggested that the mouse ST6GalNAc I gene expression is regulated by these two promoters in tissue-specific manners.

Eradication diminishes enhancing effects of Helicobacter pylori infection on glandular stomach carcinogenesis in Mongolian gerbils

To investigate the nature of the link between Helicobacter pylori (Hp) infection and stomach carcinogenesis, a study of the glandular stomach of Mongolian gerbils (MGs) was performed. MGs were treated with N-methyl-N-nitrosourea (MNU), followed by inoculation with Hp (groups 1 and 2) or without Hp (group 3), or infected with Hp (groups 4 and 5) or inoculation without Hp (group 6) followed by MNU administration. At week 21, the animals in groups 2 and 5 underwent an eradication procedure. At week 50, the incidences of adenocarcinomas in group 1 (15 of 23) and group 4 (9 of 26) were significantly higher than in group 3 (1 of 15) and group 6 (1 of 18), respectively. Moreover, those in group 2 (5 of 24) and group 5 (2 of 22) were lower than in groups 1 and 4, respectively. This study shows that Hp eradication may be useful as a prevention approach against stomach cancer.

Hepatocyte growth factor is essential for amelioration of hyperglycemia in streptozotocin-induced diabetic mice receiving a marginal mass of intrahepatic islet grafts

BACKGROUND

It is crucial for clinical islet transplantation to find a procedure to improve the success rate of insulin independence after islet transplantation. In the present study, we determined whether hepatocyte growth factor (HGF) has a favorable effect on amelioration of hyperglycemia in streptozotocin (STZ, 200 mg/kg)-induced diabetic mice (C57BL/6) receiving a marginal mass of intrahepatic islet isografts.

METHODS

Isolated syngeneic islets were transplanted into the liver of recipients. HGF with dextran sulfate (DS) was administered intraperitoneally once a day at day 0, 2, 4, 6, and 8 relative to islet transplantation. DS has been known to enhance the effect of HGF.

RESULTS

It was found that the number of 250 islets was a marginal mass as donor islets in this model, in which 2 out of 14 diabetic mice receiving 250 islets became normoglycemic by 90 days after transplantation. The treatment with HGF (100 microg) in conjunction with DS (200 microg) produced normoglycemia in all mice (n = 5). Morphological study as well as intraperitoneal glucose tolerance test revealed the beneficial effects of HGF. To our surprise, six out of nine mice receiving 250 islets and treated with DS alone became normoglycemic. Additional anti-HGF antibody treatment (100 microg, day -1, 0, 2, 4, 6, and 8) abolished the effects of DS, indicating that the effect by DS is mediated via the endogenous HGF. The effects of DS were not observed when the renal subcapsular space was the site of islet transplantation. There was a significant increase in plasma HGF levels in mice after the intrahepatic grafts but not the renal subcapsular one.

CONCLUSIONS

These findings demonstrate that HGF is essential for amelioration of hyperglycemia in STZ-induced diabetic mice when a marginal mass of islets was grafted into the liver. As the liver is the site of clinical islet transplantation and the inability to achieve insulin independence after transplantation is a major obstacle for successful transplantation, HGF may facilitate to overcome such an important issue for clinical islet transplantation.

New animal model of glandular stomach carcinogenesis in Mongolian gerbils infected with Helicobacter pylori and treated with a chemical carcinogen

In 1994 WHO/IARC concluded that "Helicobacter pylori is a definite carcinogen" based on epidemiological studies, but there have been few reports demonstrating a relation between H. pylori and stomach cancer in animal models. We have succeeded in producing adenocarcinomas in the glandular stomachs of Mongolian gerbils with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or N-methyl-N-nitrosourea as carcinogens and hope to establish an experimental stomach carcinogenesis model using H. pylori. Male Mongolian gerbils, 7 weeks old, were infected with H. pylori followed by MNNG administration at a concentration of 100ppm administration or treated with MNNG at a concentration of 300ppm in their drinking water followed by inoculation with H. pylori. They were then killed sequentially, and their excised stomachs underwent microbiological and histopathological examinations. H. pylori were detected in all infected gerbils. Hyperplastic change of pyloric mucosa was observed with high 5-bromo-2'-deoxyuridine incorporation in affected animals. H. pylori infection persists on administration of MMNG and enhances glandular stomach proliferation in Mongolian gerbils. Whether long-term colonization promotes carcinogenesis in the glandular stomach of Mongolian gerbils is a matter of great interest.

Purulent pericarditis due to group B streptococcus and mycotic aneurysm of the ascending aorta: case report

A 61-year-old female, with a history of uterine and cervical cancer treated with radical hysterectomy and 2 years of postoperative chemotherapy, presented to the emergency department with dyspnea on exertion. Computed tomography of the chest revealed a large pericardial effusion and a sacciform aneurysm of the ascending aorta. The patient subsequently underwent emergency pericardiocentesis with drainage of approximately 330 ml of a bloody and turbid effusion. Cultures from the effusion yielded group B streptococcus. Multiple organ failure and disseminated intravascular coagulation syndrome occurred in the acute phase, but gradually improved with continuous antibiotic therapy. On the 194th hospital day, in situ reconstruction of the ascending aorta was successfully performed using a synthetic graft. Although rarely reported, both purulent bacterial pericarditis and mycotic aneurysm can be life-threatening.

A novel glycosyltransferase with a polyglutamine repeat; a new candidate for GD1alpha synthase (ST6GalNAc V)(1)

The fifth type GalNAcalpha2,6-sialyltransferase (mST6GalNAc V) was cloned from a mouse brain cDNA library. mST6GalNAc V exhibited type II transmembrane topology containing a polyglutamine repeat, which showed 42.6% and 44.8% identity to mouse ST6GalNAc III and IV, respectively. Northern blot analysis revealed that the mST6GalNAc V gene was specifically expressed in forebrain and cerebellum. mST6GalNAc V exhibited GD1alpha synthetic activity from GM1b the same as mST6GalNAc III and IV. The activity ratio of GM1b toward fetuin and the expression pattern were completely different among the three ST6GalNAcs. Interestingly, the polyglutamine repeat number was different from that of inbred mice. We report the first glycosyltransferase with a polymorphic polyglutamine repeat.

Cloning and expression of a human gene encoding an N-acetylgalactosamine-alpha2,6-sialyltransferase (ST6GalNAc I): a candidate for synthesis of cancer-associated sialyl-Tn antigens

The sialyl-Tn (sTn) antigen is a well known cancer-associated antigen, the expression of which is related to the prognosis of cancer patients. We aimed to isolate a human gene encoding an N -acetylgalactosamine alpha2,6-sialyltransferase which synthesizes sTn antigen, and to characterize the enzyme. Degenerate primers encoding sialyl motifs were used for the polymerase chain reaction to amplify complementary DNAs prepared from RNAs of human pyloric mucosae with intestinal metaplasia, which abundantly expressed sTn antigen, followed by screening of full-length cDNAs using the amplified DNA fragment as a probe. We isolated two human cDNA clones, long-form (2.46 kb) and short-form (2.23 kb) cDNAs. The former encodes an active enzyme with a predicted 600 amino acid sequence. The latter, a splice-variant of the long-form, encodes an inactive enzyme. HCT15 human colorectal cancer cells stably expressing the long-form cDNA expressed sTn epitopes on O -glycans. The long form cDNA was considered to encode a human homologue of chick ST6GalNAc I for the following reasons: (1) the putative amino acid sequence showed greater homology to that of chick ST6GalNAc I (55%) compared to other sialyltransferases, (2) it encodes the extraordinarily long stem region that is a typical feature of chick ST6GalNAc I, and (3) the substrate specificity was very similar to that of chick ST6GalNAc I. In situ hybridization demonstrated that the localization of transcripts correlated well with that of sTn antigen in gastric cancer cells and Goblet cells in intestinal metaplastic glands. Thus, we determined that the long-form cDNA of the human ST6GalNAc I gene encodes the probable candidate for the human sTn synthase(s).

Molecular cloning and expression of rat antisecretory factor and its intracellular localization

Antisecretory factor (AF) was identified as a pituitary protein that inhibits the intestinal fluid secretion induced by cholera toxin. One aim of this study was to elucidate whether AF is also synthesized in the intestine or if AF produced in the pituitary is transported to the intestinal tract for its function there. cDNA clones encoding a protein proposed to be AF were isolated from rat pituitary gland and intestinal mucosa cDNA libraries. The nucleotide sequences of clones isolated from the rat pituitary gland and intestinal mucosa were identical. The deduced amino acid sequence was highly homologous to the sequence for subunit 5a of the human 26S protease that exists abundantly in the cytosol and nucleus. The production of AF in the intestine was confirmed by Northern blot and immunoblot analyses. Immunocytochemical observations of cells transfected with the rat AF cDNA showed that the AF protein was localized in the cytoplasm. These findings suggest that the protein proposed to be AF may be a cytoplasmic protein, it exists in the intestine rather than being transported from the pituitary gland, and it may function in intestinal cells.

Up-regulation of Lewis enzyme (Fuc-TIII) and plasma-type alpha1,3fucosyltransferase (Fuc-TVI) expression determines the augmented expression of sialyl Lewis x antigen in non-small cell lung cancer

Sialyl Lewis a and x antigens are well-known tumor-associated antigens expressed in many cancer tissues. The expression of the genes encoding 5 alpha1,3fucosyltransferases, which are able to synthesize the sialyl Lewis antigens, was examined in normal and cancerous lung tissues of patients with non-small cell lung carcinoma. In all 20 cases examined, the transcripts only for the Lewis gene, encoding the Lewis enzyme (alpha1,3/4fucosyltransferase, Fuc-TIII), were abundantly expressed in lung tissue, and interestingly they were markedly up-regulated in the lung cancer tissues of all 20 cases in comparison with normal lung tissues. Myeloid-type alpha1,3fucosyltransferase (Fuc-TIV) was expressed at an intermediate level but was not up-regulated in lung cancer tissues. The transcripts for plasma-type alpha1,3fucosyltransferase (Fuc-TVI) gene were detected at a very low level but were apparently up-regulated in cancer tissues. Fuc-TVI was found to exhibit stronger relative activity for sialyl Lewis x synthesis (almost 6. 4-fold that of Fuc-TIII). The amount of sialyl Lewis x antigen on mucins in the lung cancer tissues was found to be determined by both enzymes, the Lewis enzyme (Fuc-TIII) and Fuc-TVI. However, the amount of the sialyl Lewis a antigens was not determined by any of the alpha1,3-fucosyltransferases, although the expression of sialyl Lewis a antigens definitely required the Lewis enzyme.

Up-regulation of Lewis enzyme (Fuc-TIII) and plasma-type alpha1,3fucosyltransferase (Fuc-TVI) expression determines the augmented expression of sialyl Lewis x antigen in non-small cell lung cancer

Sialyl Lewis a and x antigens are well-known tumor-associated antigens expressed in many cancer tissues. The expression of the genes encoding 5 alpha1,3fucosyltransferases, which are able to synthesize the sialyl Lewis antigens, was examined in normal and cancerous lung tissues of patients with non-small cell lung carcinoma. In all 20 cases examined, the transcripts only for the Lewis gene, encoding the Lewis enzyme (alpha1,3/4fucosyltransferase, Fuc-TIII), were abundantly expressed in lung tissue, and interestingly they were markedly up-regulated in the lung cancer tissues of all 20 cases in comparison with normal lung tissues. Myeloid-type alpha1,3fucosyltransferase (Fuc-TIV) was expressed at an intermediate level but was not up-regulated in lung cancer tissues. The transcripts for plasma-type alpha1,3fucosyltransferase (Fuc-TVI) gene were detected at a very low level but were apparently up-regulated in cancer tissues. Fuc-TVI was found to exhibit stronger relative activity for sialyl Lewis x synthesis (almost 6. 4-fold that of Fuc-TIII). The amount of sialyl Lewis x antigen on mucins in the lung cancer tissues was found to be determined by both enzymes, the Lewis enzyme (Fuc-TIII) and Fuc-TVI. However, the amount of the sialyl Lewis a antigens was not determined by any of the alpha1,3-fucosyltransferases, although the expression of sialyl Lewis a antigens definitely required the Lewis enzyme.

Molecular mechanism involved in increased expression of sialyl Lewis antigens in ductal carcinoma of the pancreas

Increased expression of sialyl Lewis antigens, sLe(a) and sLe(x), is frequent during malignant transformation and tumor progression of gastrointestinal cancers and it is assumed to be correlated with the increased metastatic potential of tumor cells and, consequently, with poor patient survival. To determine the influence of the increased expression of these antigens in disease progression of ductal carcinoma of the pancreas, immunohistochemical expressions of sLe(x) and sLe(a) in 51 ductal carcinomas of the pancreas were examined. We also examined the expression of glycosyltransferase genes, which are involved in the synthetic pathways of these antigens to understand the molecular mechanism involved in the increased expression of these antigens. Of the 51 primary ductal carcinomas of the pancreas, 40 (78.4%) were sLe(a)-positive and 11 (21.6%) were sLe(a)-negative; 16 (31.4%) were sLe(x)-positive and 35 (68.6%) were sLe(x)-negative. Although there were no significant differences in any examined clinicopathological factors such as age, sex, histological type, tumor size, presence of lymph node metastasis, or presence of vessel invasion between the positive and negative groups with both the sLe(a) and sLe(x) antigens, patient survival tended to be worse in the antigens-positive group than in the antigens-negative group. Increased expression, however, was not dependent on the increased expression of a single glycosyltransferase gene examined among five such genes, which are postulated to be responsible for the synthesis of the sLe(a) and sLe(x) epitopes in the glycosylation pathway. Furthermore, the increased expression of these antigens was not closely associated with mutations status of the K-ras or p53 genes. These findings suggested that increased expression of sialyl Lewis antigens are involved in pancreatic tumorigenesis and that the accumulation of genetic alterations or epigenetic changes is responsible for the molecular mechanisms of increased expression of the sLe(a) and sLe(x) antigens in ductal carcinomas of pancreas.

Intracellular cleavage of glycosylphosphatidylinositol by phospholipase D induces activation of protein kinase Calpha

Many proteins are anchored to the cell membrane by glycosylphosphatidylinositol (GPI). One of the functions proposed for the GPI anchor is as a possible mediator in signal transduction through its hydrolysis. GPI-specific phospholipase D (GPI-PLD) is a secretory protein that is suggested to be involved in the release of GPI-anchored protein from the membrane. In the present study we examined how GPI-PLD is involved in signal transduction. When introduced exogenously and overexpressed in cells, GPI-PLD cleaved the GPI anchors in the early secretory pathway, possibly in the endoplasmic reticulum, resulting in an increased production of diacylglycerol. Experiments in vitro and in vivo showed that the association of protein kinase Calpha (PKCalpha) with membranes was increased markedly by expression of GPI-PLD in cells. Furthermore, sucrose-density-gradient centrifugation and immunofluorescence microscopy demonstrated that PKCalpha was translocated to the endoplasmic reticulum membrane in cells expressing GPI-PLD, in contrast with its association with the plasma membrane in cells treated with PMA. We also confirmed that the phosphorylation of c-Fos as well as PKCalpha itself was greatly enhanced by the expression of GPI-PLD. Taken together, these results suggest that GPI-PLD is involved in intracellular cleavage of the GPI anchor, which is a new potential source of diacylglycerol production to activate PKCalpha.

An immunohistochemical study of beta1,4-galactosyltransferase in human skin tissue

An immunohistochemical investigation of beta1,4-galactosyltransferase (beta1,4-GalT) on human skin tissue was performed on formalin-fixed paraffin-embedded sections using a monoclonal antibody, MAb8628, which specifically recognizes a protein moiety of human beta1,4-GalT. Distribution of the galactose beta1,4-N-acetylglucosamine (Gal beta1,4GlcNAc)-R epitope was also detected by staining with Ricinus communis agglutinin (RCA) 120. The beta1,4-GalT was observed to be localized at the perinuclear region of epidermal keratinocytes. The fine localization was also observed at the supranuclear region in the cells of apocrine glands, eccrine ducts and glands. The positive staining with RCA 120 was well colocalized with the cells expressing the beta1,4-GalT. An electron microscopic study revealed that positive signals of beta1,4-GalT definitely reside in the Golgi apparatus. No immunoreactivity was observed in any other intracellular structure or on the cell surface. These findings strongly indicated that the beta1,4-GalT is the major enzyme responsible for the Gal beta1,4GlcNAc-R epitope synthesis in human skin tissue.

Alpha1,3-fucosyltransferase IX (Fuc-TIX) is very highly conserved between human and mouse; molecular cloning, characterization and tissue distribution of human Fuc-TIX

The amino acid sequence of Fuc-TIX is very highly conserved between mouse and human. The number of non-synonymous nucleotide substitutions of the Fuc-TIX gene between human and mouse was strikingly low, and almost equivalent to that of the alpha-actin gene. This indicates that Fuc-TIX is under a strong selective pressure of preservation during evolution. The human Fuc-TIX (hFuc-TIX) showed a unique characteristics, i.e. hFuc-TIX was not activated by Mn2+ and Co2+, whereas hFuc-TIV and hFuc-TVI were activated by the cations. The hFuc-TIX transcripts were abundantly expressed in brain and stomach, and interestingly were detected in spleen and peripheral blood leukocytes.

Molecular mechanisms of expression of Lewis b antigen and other type I Lewis antigens in human colorectal cancer

Lewis b (Leb) antigens are gradiently expressed from the proximal to the distal colon, i.e., they are abundantly expressed in the proximal colon, but only faintly in the distal colon. In the distal colon, they begin to increase at the adenoma stage of cancer development and then increase with cancer progression. We aimed to clarify the molecular basis of Leb antigen expression in correlation with the expression of other type I Lewis antigens, such as Lewis a (Lea) and sialylated Lewis a (sLea), in colon cancer cells. Considering the Se genotype and the relative activities of the H and Se enzymes, the amounts of Leb antigens were proved to be determined by both the H and Se enzymes in noncancerous and cancerous colon tissues. But the Se enzyme made a much greater contribution to determining the Lebamounts than the H enzyme. In noncancerous colons, the Se enzyme were gradiently expressed in good correlation with the Leb expression, while the H enzyme was constantly expressed throughout the whole colon. In distal colon cancers, the H and Se enzymes were both significantly upregulated in comparison with in adjacent noncancerous tissues. In proximal colon cancers, expression of the H enzyme alone was highly augmented. The augmented expression of Leb antigens in distal colon cancers is caused mainly by upregulation of the Se enzyme and partly by the H enzymes, while it is caused by upregulation of the H enzyme alone in proximal colon cancers. The Se gene dosage profoundly influences the amounts of the Leb, Lea, and sLea antigens in whole colon tissues, regardless of whether they are noncancerous or cancerous tissues. It suggests that the Se enzyme competes with alpha2,3 sialyltransferase(s) and the Le enzyme for the type I acceptor substrates.

Effects of low dose catechol on glandular stomach carcinogenesis in BALB/c mice initiated with N-methyl-N-nitrosourea

The effects of low dose catechol administration in the diet on stomach carcinogenesis in mice after initiation with N-methyl-N-nitrosourea (MNU) in the drinking water were investigated. Male, 6-week-old, BALB/c mice were given MNU in the drinking water intermittently for 1-week periods at 1-week intervals for a total of 3 weeks at a concentration of 120 ppm (groups 1 and 3). Groups 2 and 4 served as non-initiated controls. From week 7, groups 1 and 3 were divided into four subgroups and the mice were fed on a diet containing 4 ppm (groups la and 3a), 20 ppm (groups 1b and 3b), 100 ppm (groups 1c and 3c), 500 ppm (groups 1d and 3d) or 0 ppm (groups 2 and 4) catechol for 44 weeks. At week 50, appreciably enhanced development of pepsinogen 1 altered pyloric glands (PAPG) was noted in groups 1c and 1d. The incidences of adenomatous hyperplasia and carcinomas were not affected in any of the catechol-treated groups as compared with corresponding controls on a basal diet. Thus, the administration of catechol in the diet at low doses enhanced only preneoplastic lesion development and not neoplastic lesion development. From these results, we conclude that the biological significance of the catechol promoting effect at probable human exposure levels on gastric cancer is probably limited, while the PAPG may be a sensitive endpoint lesion for mouse glandular stomach carcinogenesis.

Molecular behavior of mutant Lewis enzymes in vivo

The expression of type-1 Lewis antigens on erythrocytes and in digestive organs is determined by a Lewis type alpha(1,3/1, 4)-fucosyltransferase (Lewis enzyme) encoded by the Fuc-TIII gene ( FUT3 gene; Lewis gene). We have classified the Lewis alleles in the Japanese population into four types, the wild-type allele ( Le ) and three mutated alleles, i.e., le1, which has missense mutations T59G and G508A, le2, which has T59G and T1067A, and le3, which has only T59G. Here we carried out an extensive study on the biological properties of the three mutant Lewis enzymes, the le1, le2, and le3 enzymes, using native tissues and obtained the following results. (1) In in vivo and in vitro experiments, the le1 and le2 enzymes were found to be susceptible to protease digestion probably because the one missense mutation in the catalytic domains, i.e., Gly170 to Ser in the le1 enzyme and Ile356 to Lys in the le2 enzyme, makes the three-dimensional structures of the enzymesunstable, while the le3 and wild-type Lewis enzymes wereresistant to protease digestion. (2) The le1 and le2 enzymes cannot synthesize type 1 Lewis antigens on either glycolipids or mucins. The le3 enzyme cannot synthesize Lewis-active glycolipids, which result in the Lewis antigen-negative phenotype of erythrocytes, while it can synthesize Lewis antigens on mucins in normal and cancerous colon tissues. The missense mutation, Leu20 to Arg, in the transmembrane domain reduces retention of the le3 enzyme in the Golgi membrane resulting in an apparent reduction of enzyme activity as revealed by the lack of Lewis antigen synthesis. (3) The Lewis gene dosage actually has effects in vivo on the amount of the Lewis enzyme, its activity, and finally the amounts of Lewis carbohydrate antigens. This is the first article that clearly demonstrates the gene dosage effects on the amount of the glycosyltransferase protein, its activity, and the amounts of carbohydrate products in vivo.

Helicobacter pylori infection enhances glandular stomach carcinogenesis in Mongolian gerbils treated with chemical carcinogens

Helicobacter pylori (Hp) is thought to be a stomach carcinogen from epidemiological findings. To determine the effects of infection with the bacteria on experimental carcinogenesis, a study of the glandular stomach of Mongolian gerbils (MGs) was performed. Male MGs were treated with N-methyl-N'-nitro-N-nitrosoguanidine followed by inoculation with Hp or infected with Hp followed by N-methyl-N'-nitro-N-nitrosoguanidine administration. Animals were killed at week 50, and their excised stomachs underwent microbiological and histopathological examinations. In addition, a serological investigation was performed. The incidences of adenocarcinomas were significantly higher in animals treated with 60 or 300 p.p.m. N-methyl-N'-nitro-N-nitrosoguanidine for 10 weeks followed by Hp inoculation or Hp followed by 20 p.p.m. N-methyl-N'-nitro-N-nitrosoguanidine for 30 weeks than in the respective controls. Moreover, tumour-bearing animals had higher titres of anti-Hp antibodies than tumour-free animals. Of interest was the finding that a dose of 100 p.p.m. N-methyl-N'-nitro-N-nitrosoguanidine given to infected gerbils eradicated the Hp in about half the animals, with a concomitant reduction in the promoting effect. No tumours were found in animals infected with Hp without N-methyl-N'-nitro-N-nitrosoguanidine or non-treated gerbils. Hp infection enhances glandular stomach carcinogenesis in MGs treated with N-methyl-N'-nitro-N-nitrosoguanidine. Animals with high titres of anti-Hp antibodies are at greatest risk of developing neoplasms.

The aberrant expression of Lewis a antigen in intestinal metaplastic cells of gastric mucosa is caused by augmentation of Lewis enzyme expression

Immunohistochemical staining showed an aberrant expression of Le(a) antigen in the intestinal metaplastic glands of the gastric mucosa of secretors, as reported by others. In this study, we have demonstrated for the first time that the Lewis enzyme is well colocalized with Le(a) antigen, indicating that the Lewis enzyme is responsible for Le(a) antigen synthesis in the gastric mucosa. The staining intensity of the Lewis enzyme was much stronger in the cells with intestinal metaplasia than the cells without metaplasia, regardless of the secretor status. The amount of transcript of the Lewis gene was related to the degree of metaplasia; i.e., the more severe the metaplastic change was, the more abundantly the transcripts of the Lewis gene were expressed. This augmentation of the Lewis enzyme in metaplastic tissues was also confirmed by Western blotting analysis using a specific antibody against the Lewis enzyme. We conclude that intestinal metaplastic change of gastric mucosa is usually accompanied by a marked augmentation of the Lewis enzyme expression, which results in the enhanced expression of Le(a) antigens, particularly in secretors.

Dynamic recycling of ERGIC53 between the endoplasmic reticulum and the Golgi complex is disrupted by nordihydroguaiaretic acid

Nordihydroguaiaretic acid (NDGA), an inhibitor of lipoxygenase, has recently been demonstrated to block protein transport from the endoplasmic reticulum (ER) to the Golgi complex. The ER to Golgi transport is primarily operated by the ER-Golgi intermediate compartment (ERGIC). We examined the effect of NDGA on the ERGIC, focusing on the distribution of its marker ERGIC53. In control cells ERGIC53 was distributed to vesicular tubular structures corresponding to the ERGIC as well as to the ER and the cis-Golgi, reflecting its cycling between these compartments. Upon treatment of cells with NDGA, ERGIC53 was rapidly accumulated in the Golgi and undetectable in the ER and the ERGIC. Prolonged incubation of cells with the drug, however, caused redistribution of ERGIC53 and resident Golgi proteins to the ER. Thus, it is likely that NDGA has dual effects on ERGIC53 cycling; the initial accumulation in the Golgi may be caused by blocking its retrieval from the cis-Golgi to the ER/ERGIC, while the delayed redistribution to the ER may occur through a pathway induced by the drug that is different from the COPI-dependent pathway.

Novel carbohydrate specificity of monoclonal antibody 91.9H prepared against human colonic sulfomucin: recognition of sulfo-Lewis(a) structure

Monoclonal antibody (mAb) 91.9H was previously prepared against partially purified human colonic sulfomucins. The epitope was detected in normal colonic mucosa and primary and metastatic colorectal carcinoma in decreasing order of magnitude. In the present study, this antibody was shown to recognize sulfo-Le(a) structure, HSO3-3Gal beta 1-3(Fuc alpha 1-4)GlcNAc. Interactions between mAb 91.9H and synthetic oligosaccharides conjugated with biotinylated polyacrylamide carrier were examined by a biosensor based on surface plasmon resonance and by enzyme-linked immunosorbent assays. This mAb bound to sulfo-Lea but not to sulfo-LeX, Le(a), LeX, sialyl-Le(a), or sialyl-LeX. Sulfo-Le(a) oligosaccharides decreased its binding affinity with mAb 91.9H after periodate oxidation of its fucose residue. Immunohistochemical study showed a strong binding of mAb 91.9H to goblet cells in human colonic epithelia of Lewis-positive individuals but a trace binding in Lewis-negative individuals, confirming the specificity of this antibody toward structures containing a fucosylated type 1 backbone.

Posttranslational modification of glycosylphosphatidylinositol (GPI)-specific phospholipase D and its activity in cleavage of GPI anchors

Human glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) was exogenously expressed in mammalian CHO cells and in insect H5 cells. GPI-PLD was initially synthesized as a 105-kDa form and then secreted as a mature 115-kDa form from the CHO cells, whereas it was secreted as an immature 98-kDa form from the H5 cells. The difference of the molecular forms was caused by its oligosaccharide processing in the two cell lines. These forms showed a different reactivity to anti-C-terminal peptide of GPI-PLD; the 105-kDa and 98-kDa forms were directly recognized by the antibodies, whereas the 115-kDa form was immunoreactive only after being denatured. In an in vitro assay, the 98-kDa form but not the 115-kDa form was able to release a significant amount of GPI-anchored proteins from intact membranes, although the two forms had the same GPI-anchor cleavage activity in the presence of detergents. In addition, a GPI-anchored protein, when coexpressed in CHO cells, was intracellularly cleaved by GPI-PLD in the secretory pathway. Taken together, these results suggest that GPI-PLD undergoes a conformational change by posttranslational modification, which affects its immunoreactive and enzymatic properties.

Expression cloning and characterization of a novel murine alpha1, 3-fucosyltransferase, mFuc-TIX, that synthesizes the Lewis x (CD15) epitope in brain and kidney

The 3-fucosyl-N-acetyllactosamine (Lewis x, CD15, SSEA-1) carbohydrate epitope is widely distributed in many tissues and is developmentally expressed in some rodent and human tissues, i.e. brain and lung, and mouse early embryo. In such tissues, the Lewis x epitope is considered to be involved in cell-cell interactions. We isolated a novel mouse alpha1,3-fucosyltransferase gene, named mFuc-TIX, from an adult mouse brain cDNA library using the expression cloning method. On flow cytometric analysis, Namalwa cells transfected stably with the mFuc-TIX gene showed a marked increase in Lewis x epitopes but not sialyl Lewis x epitopes. As seen experiments involving oligosaccharides as acceptor substrates, mFuc-TIX transfers a fucose to lacto-N-neotetraose but not to either alpha2,3-sialyl lacto-N-neotetraose or lacto-N-tetraose. The substrate specificity of mFuc-TIX was similar to that of mouse myeloid-type alpha1,3-fucosyltransferase (mFuc-TIV). The deduced amino acid sequence of mFuc-TIX, consisting of 359 residues, indicated a type II membrane protein and shows low degrees of homology to the previously cloned alpha1,3-fucosyltransferases, i.e. mFuc-TIV (48.4%), mouse Fuc-TVII (39.1%), and human Fuc-TIII (43.0%), at the amino acid sequence level. A phylogenetic tree of the alpha1, 3-fucosyltransferases constructed by the neighbor-joining method showed that mFuc-TIX is quite distant from the other alpha1, 3-fucosyltransferases. Thus, mFuc-TIX does not belong to any subfamilies of known alpha1,3Fuc-Ts. The mFuc-TIX transcript was mainly detected in brain and kidney with the Northern blotting and competitive reverse transcription-polymerase chain reaction methods, whereas the mFuc-TIV transcript was not detected in brain with these methods. On in situ hybridization, the mFuc-TIX transcript was detected in neuronal cells but not in the glial cells including astrocytes. These results strongly indicated that mFuc-TIX participates in the Lewis x synthesis in neurons of the brain and may be developmentally regulated.

Elevation of alpha2-->6 sialyltransferase and alpha1-->2 fucosyltransferase activities in human choriocarcinoma

Structures of N-linked sugar chains are species and tissue specific and change in the course of tumorigenesis. Sialyl linkages of human placental glycoproteins are exclusively Neu5Ac alpha2-->3Gal, whereas Fuc alpha1-->2Gal and Neu5Ac alpha2-->6Gal residues are expressed in human chorionic gonadotropin and alkaline phosphatase, which are produced in human choriocarcinoma JEG-3 and BeWo cells. In the present study, to elucidate the enzymological and molecular biological basis of the structural changes that occur in the course of tumorigenesis, alpha1-->2 fucosyltransferase, alpha2-->3 and alpha2-->6 sialyltransferase activities, and the expression levels of the corresponding mRNAs were measured. The alpha2-->3 sialyltransferase activity did not change as a result of tumorigenesis; however, the alpha2-->6 siayltransferase activity and alpha1-->2 fucosyltransferase activity in JEG-3 and BeWo cells increased to levels several times higher than those in placenta Competitive PCR analysis showed that the expression levels of mRNA encoding alpha1-->2 fucosyltransferase and mRNA encoding alpha2-->6 sialyltransferase increased significantly as a result of tumorigenesis, indicating that such structural changes are regulated at the level of transcription of these glycosyltransferase genes.

Mammalian glycophosphatidylinositol anchor transfer to proteins and posttransfer deacylation

The glycophosphatidylinositol (GPI) anchors of proteins expressed on human erythrocytes and nucleated cells differ with respect to acylation of an inositol hydroxyl group, a structural feature that modulates their cleavability by PI-specific phospholipase C (PI-PLC). To determine how this GPI anchor modification is regulated, the precursor and protein-associated GPIs in two K562 cell transfectants (ATCC and .48) exhibiting alternatively PI-PLC-sensitive and resistant surface proteins were analyzed and the temporal relationship between GPI protein transfer and acquisition of PI-PLC sensitivity was determined. Nondenaturing PAGE analyses demonstrated that, whereas in .48 transfectants the GPI anchors in decay accelerating factor (DAF) and placental alkaline phosphatase (PLAP) were >95% acylated, in ATCC transfectants, they were 60 and 33% unsubstituted, respectively. In contrast, TLC analyses revealed that putative GPI donors in the two lines were identical and were >/=95% acylated. Studies of de novo DAF biosynthesis in HeLa cells bearing proteins with >90% unacylated anchors showed that within 5 min at 37 degreesC (or at 18 degreesC, which does not permit endoplasmic reticilum exit), >50% of the anchor in nascent 44-kDa proDAF protein exhibited PI-PLC sensitivity. In vitro analyses of the microsomal processing of miniPLAP, a truncated PLAP reporter protein, demonstrated that the anchor donor initially transferred to prominiPLAP was acylated and then progressively was deacylated. These findings indicate that (i) the anchor moiety that initially transfers to nascent proteins is acylated, (ii) inositol acylation in mature surface proteins is regulated via posttransfer deacylation, which in general is cell-specific but also can be protein-dependent, and (iii) deacylation occurs in the endoplasmic reticulum immediately after GPI transfer.

The aberrant expression of Lewis a antigen in intestinal metaplastic cells of gastric mucosa is caused by augmentation of Lewis enzyme expression

Immunohistochemical staining showed an aberrant expression of Le(a) antigen in the intestinal metaplastic glands of the gastric mucosa of secretors, as reported by others. In this study, we have demonstrated for the first time that the Lewis enzyme is well colocalized with Le(a) antigen, indicating that the Lewis enzyme is responsible for Le(a) antigen synthesis in the gastric mucosa. The staining intensity of the Lewis enzyme was much stronger in the cells with intestinal metaplasia than the cells without metaplasia, regardless of the secretor status. The amount of transcript of the Lewis gene was related to the degree of metaplasia; i.e., the more severe the metaplastic change was, the more abundantly the transcripts of the Lewis gene were expressed. This augmentation of the Lewis enzyme in metaplastic tissues was also confirmed by Western blotting analysis using a specific antibody against the Lewis enzyme. We conclude that intestinal metaplastic change of gastric mucosa is usually accompanied by a marked augmentation of the Lewis enzyme expression, which results in the enhanced expression of Le(a) antigens, particularly in secretors.

Up-regulation of a set of glycosyltransferase genes in human colorectal cancer

The carbohydrate structures of glycoconjugates of cancer cells change markedly in comparison with those of noncancerous cells. We aimed to determine which glycosyltransferases are up-regulated or down-regulated in human colon cancer tissues in order for the dramatic change in carbohydrate structures to occur. The transcript levels of 12 glycosyltransferase genes were measured by a competitive reverse-transcription-PCR method in noncancerous and cancerous colorectal tissues. Eight well- to moderately differentiated and three poorly differentiated carcinomas were examined in comparison with noncancerous colon epithelial tissues adjacent to the carcinoma tissues. Two of the twelve glycosyltransferase genes, Fuc-TIV and ST3Gal II, were significantly up-regulated in all cancerous tissues regardless of the histologic features. Four genes, ST3Gal I, ST6Gal I, beta1,4GalT, and Core2 GnT, showed a tendency toward up-regulation, and a ST3Gal III gene showed a tendency toward down-regulation. The other genes, Fuc-TIII, Fuc-TVI, and ST3Gal IV, which were most abundantly expressed in colorectal tissues, did not show significant up-regulation except in the poorly differentiated carcinomas. The Fuc-TVII gene was expressed at a very low level and was not up-regulated, and the Fuc-TV gene was not expressed at all in the colorectal tissues. Interestingly, all of the 12 glycosyltransferase genes examined, except the Fuc-TV, Fuc-TVI, Fuc-TVII, and ST3Gal III genes, were markedly up-regulated in all of the poorly differentiated carcinomas. We concluded that multiple glycosyltransferase genes are up-regulated, probably leading to extensive glycosylation of glycoconjugates in colorectal cancer cells. Lastly, sialyl Lewis antigens, ie, sialyl Lewis x and a antigens, which are terminal epitopes of sugar chains and well known as tumor-associated antigens, were quantified by Western blotting analysis. Based on the levels of transcripts of the 12 enzymes together with the amounts of sialyl Lewis antigens, we concluded that Fuc-TIII, Fuc-TVI, and ST3Gal IV are mainly responsible for synthesis of the sialyl Lewis antigens in colon tissues, but are not responsible for the augmented expression of the antigens in colorectal cancers. The amounts of sialyl Lewis x and a epitopes on mucins in colon cancer tissues can thus be determined through combinatorial up-regulation of the multiple glycosyltransferase genes.