Expression of an isoform of the testis-specific estrogen sulfotransferase in the murine placenta during the late gestational period

Cytosolic sulfotransferases play essential roles in regulating the activities and transfer of steroids. To evaluate their biological significance in the murine uterus and placenta during the course of gestation, we determined their activities with several steroids as substrates. Activated estrogen sulfotransferase (EST) was found in the placenta and uterus during the late gestational period. Reverse-transcribed cDNA of murine placental EST (mpEST) was isolated from mouse placenta at 18 days of gestation and its expression in the tissue coincided with a change in its enzyme activity. The open-reading frame of mpEST encodes a protein composed of 296 amino acids with a predicted molecular mass of 35.5 kDa and was revealed to be an isoform of the murine testis-specific EST gene (99.7%). Also, the amino acid sequence of mpEST showed 49.6 and 77.9% homology with human placental and endometrial EST, respectively, showing that it corresponds to human endometrial EST. COS-7 cells transfected with mpEST exhibited sulfotransferase activity with the phenolic hydroxy groups of steroids and artificial substrates. The best acceptor substrate was estrogen.

Characterization of three members of murine alpha1,2-fucosyltransferases: change in the expression of the Se gene in the intestine of mice after administration of microbes

We cloned three members of a GDP-fucose:beta-galactoside alpha1,2-fucosyltransferase (alpha1,2-fucosyltransferase) family, MFUT-I, -II, and -III, from a cDNA of murine small intestine, and determined their enzymatic properties after transfection of the genes into COS-7 cells, and their expression in murine tissues by Northern blotting. MFUT-I, -II, and -III exhibited sequence homology with the human H (78.4%), Se (79.0%), and Sec1 (74.9%) gene products, respectively. COS-7 cells transfected with MFUT-I and -II exhibited alpha1,2-fucosyltransferase activity and the best acceptor substrate for both gene products was GA1 to yield a fucosyl GA1 structure, but no activity was detected in COS-7 cells with MFUT-III. MFUT-II yielded a 3.5-kb mRNA transcript in several tissues, whereas MFUT-I and -III were predominantly expressed in epididymis and testis, respectively. The administration of microbes into germ-free mice resulted in a rapid increase of the MFUT-II gene (Se gene) for the synthesis of fucosyl GA1 in the intestine.

Impaired spreading of surfactant phospholipids in the lungs of newborn rats with pulmonary hypoplasia as a model of congenital diaphragmatic hernia induced by nitrofen

In order to clarify the pathological outcome of congenital diaphragmatic hernia (CDH), we devised an animal model of CDH by administration of 2,4-dichlorophenyl-p-nitrophenyl ether (nitrofen) to pregnant rats, and determined the level and distribution of lung surfactant using the monoclonal antibody toward sphingomyelin and disaturated phosphatidylcholine (disat-PC). In control rats, the concentration of disat-PC was found to increase greatly from 16 to 18 days of gestation. Intragastric administration of nitrofen to pregnant rats at day 9 of gestation resulted in CDH in 42.7% of fetuses delivered after 20 days of gestation. In nitrofen-treated fetuses, the concentration of disat-PC in the lungs was lower than those in control fetuses, and surfactant apoprotein SP-A was similarly reduced in nitrofen-treated fetuses. However, the concentration of disat-PC in nitrofen-treated fetuses was higher than that in control fetuses at 18 days of gestation, indicating a synthetic potential of surfactant in nitrofen-treated fetuses comparable to that at the late stage of normal gestation. Immunohistochemical study with the antibody revealed that surfactant phospholipid was mainly in the form of intracellular granules in nitrofen-treated fetuses, probably causing the hypoplastic lungs and then CDH, in contrast to the uniform distribution on the pulmonary alveolar surface in control fetuses.

Enhanced expression of a-series gangliosides in fibroblasts of patients with peroxisome biogenesis disorders

Peroxisome biogenesis disorders (PBD) are classified into Zellweger syndrome (ZS), infantile Refsum disease (IRD) and neonatal adrenoleukodystrophy. Disturbances in the differentiation of neural cells such as migration arrest are characteristic of PBD. So far the pathogenesis of these disturbances is not clearly understood. We describe an altered metabolism of glycosphingolipids in PBD which has not yet been investigated. We observed an increased amount of a-series gangliosides, GM2, GM1 and GD1a, in the fibroblasts of patients with ZS and IRD. Gangliosides GM1 and GD1a were not present in detectable amounts in normal subjects. A key step in the synthesis of a-series gangliosides is a transfer of GalNAc to ganglioside GM3, so we determined the level of ganglioside GM3 by immunohistochemical methods. We found a granular structure, which was positive toward anti-ganglioside GM3 antibody in the cytoplasm of the patients' fibroblasts. In control cells, the cell membrane was slightly positive toward anti-GM3 antibody. These results may help to clarify the pathogenesis of PBD with respect to the functional roles of glycosphingolipids in cell differentiation, proliferation and apoptosis.

Comparative analysis of colonization of Helicobacter pylori and glycolipids receptor density in Mongolian gerbils and mice

The Mongolian gerbil has been used as an excellent experimental animal model for studying Helicobacter pylori infection because it can stably colonize and induce severe chronic gastritis, ulceration, and cancer-simulating human diseases in this animal. In contrast, H. pylori can only induce mild inflammation in many mouse models. The aim in this study is to clarify the difference of induction of pathological lesions in the two animal models. SPF ICR mice and Mongolian gerbils were inoculated with a clinically isolated strain of H. pylori. Six weeks after inoculation, bacteria colonizing the stomach were counted. Immunohistochemical staining and biochemical analyses of three putative receptor glycolipids were performed with monoclonal antibodies to the respective glycolipids. Significantly higher numbers of H. pylori were recovered from the stomachs of Mongolian gerbils than mice (5.77 +/- 0.46 log CFU vs 4.17 +/- 0.55 log CFU, P < 0.01). Immunohistochemical studies showed that sulfatide expression in the gastric mucosa of Mongolian gerbils was much stronger than that in mice, whereas the expression of Lewis(b) glycolipid and GM3 were almost equal. Quantitative analysis of each glycolipid by thin-layer chromatography confirmed the results of immunohistochemical study, showing 4.1 times higher sulfatide content in the Mongolian gerbil stomach. The content of both Lewis(b) and GM3 was almost equivalent in these two animals. In conclusions, higher levels of sulfatide expression, a putative adhesion receptor, in the gastric mucosa of Mongolian gerbils may allow abundant colonization by H. pylori, resulting in the development of gastric lesions in this animal model.

Inhibitory activity of sulphoglycolipid derivatives towards pancreatic trypsin

Amphipathic sulpholipids have been shown to inhibit pancreatic serine proteases due to their detergent-like properties. To evaluate the structural requirement for this inhibitory activity, we examined the effects of various derivatives of sulphoglycolipids, some of which were prepared by deacylation with sphingolipid ceramide N-deacylase, followed by acylation with acyl chloride, on the activity of pancreatic trypsin. Both deacylated sulphatides and seminolipids exhibited inhibitory activity towards trypsin without any requirement for solubilisation and preincubation. On the other hand, stronger inhibition was observed for acylated sulphatides than for deacylated ones, but increasing the chain length of the fatty acid moiety resulted in the need for a solubilisation agent and preincubation in order to achieve maximal inhibitory activity. The structural isomers of sulphoglycolipids, such as I(6)SO(3)-GalCer, and phytosphingosine- and diglyceride-containing sulphoglycolipids, showed similar inhibitory activity, indicating the involvement of sulphate and hydrophobic groups, irrespective of the fine structure, in the inhibition. Among the sulphoglycolipids examined, II(3)SO(3)-LacCer was found to exhibit the highest inhibitory activity.

Shedding of sulfated lipids into gastric fluid and inhibition of pancreatic DNase I by cholesterol sulfate in concert with bile acids

Cholesterol sulfate (CS) and sulfatides in the epithelium of the digestive tract were found in the 1000xg supernatants of digestive fluid, particularly in gastric juices containing the duodenal contents and bile acids, there being 14-131 microg of CS and 3-54 microg of sulfatides per mg of protein in the fluid, respectively. CS and sulfatides dissolved in detergents including bile acids inactivated pancreatic trypsin to the same level as by DMSO-solubilized sulfated lipids at 37 degrees C. Similarly, pancreatic DNase I was inhibited by CS solubilized with DMSO or bile acids, but not by sulfatides or other membrane lipids at 37 degrees C. Both the sulfate group and the hydrophobic side chain of CS were indispensable structures for the inhibition of DNase I. Also, the optimum molar ratio of bile acids to CS was important for expression of the inhibitory activity of CS toward DNase I, it being 0.18 of the optimum ratio for sodium taurocholate, and the molar ratio of CS to DNase I for complete inhibition was 342:1. Thus, CS was shown to play a role as an epithelial inhibitor of DNase I in concert with bile acids.

GDP-fucose: beta-galactoside alpha1,2-fucosyltransferase, MFUT-II, and not MFUT-I or -III, is induced in a restricted region of the digestive tract of germ-free mice by host-microbe interactions and cycloheximide

A shift from sialylation to fucosylation of mucosal glycoconjugates occurred in the mammalian digestive tract in the weaning period, but mice under germ-free conditions were found to express both fucosyl GM1 (FGM1) and fucosyl asialo GM1 (FGA1) in the stomach, cecum and colon, but not in the small intestine. By host-microbe interactions and administration of cycloheximide, FGA1 was quickly induced in the small intestine, but the concentrations of fucosylated glycolipids in the other regions were not altered significantly. Their expression coincided with the activity of GDP-fucose:GA1 alpha(1, 2)-fucosyltransferase (alpha1,2-FT), and we isolated a cDNA with an open reading frame encoding the murine alpha1,2-FT (MFUT-II) of 347 amino acids with a predicted molecular mass of 39.21 kDa. The intraperitoneal injection of cycloheximide induced the mRNA and activity of alpha1,2-FT (MFUT-II) in the small intestine of germ-free mice, whereas no change in the mRNA or activity was observed in the stomach, cecum and colon, indicating that expression of FGA1 in response to microbial colonization or cycloheximide is transcriptionally regulated in a restricted region of the murine digestive tract. At 24 h after the administration of cycloheximide, FGA1 was preferentially produced in the upper half of the duodenal microvilli.

Accumulation of glycolipids in mutant Chinese hamster ovary cells (Z65) with defective peroxisomal assembly and comparison of the metabolic rate of glycosphingolipids between Z65 cells and wild-type CHO-K1 cells

The influence of peroxisomal dysfunction on glycosphingolipid metabolism was investigated using mutant Chinese hamster ovary (CHO) cells (Z65) with defective assembly of the peroxisomal membranes. In accordance with previous observations, the concentration of very long chain fatty acid (C24:0) was shown to be higher in Z65 cells than in control cells. We then compared the composition of glycolipids in Z65 cells with that in CHO-K1 cells, which are wild-type Chinese hamster ovary cells with intact peroxisomes, and found significantly increased concentrations of ceramide monohexoside (CMH) and ganglioside GM3 in Z65 cells. However, there were no differences in the concentrations of glycerophospholipids, triglycerides, free fatty acids and cholesterol between Z65 and CHO-K1 cells. Further, to investigate the metabolic rate of the major lipids, Z65 and CHO-K1 cells were pulse-labeled with [3-14C]serine. [3-14C]Serine was incorporated into phosphatidylserine, phosphatidylethanolamine and sphingomyelin more quickly in CHO-K1 than in Z65 cells. However, after 48 h, the radioactivity incorporated into those lipids, including CMH, was greater in Z65 cells than in CHO-K1 cells. Thus, the altered metabolism of glycosphingolipids, probably due to peroxisomal dysfunction, was thought to be responsible for the change in glycosphingolipid composition in Z65 cells.

Regulation of the activities of thrombin and plasmin by cholesterol sulfate as a physiological inhibitor in human plasma

Thrombin and plasmin, both of which are serine proteases in the plasma of vertebrates, play essential roles in blood clotting and fibrinolysis, respectively, and regulation of their activities is important to suppress the excessive reactions within the vascular network and to prevent tissue injury. Along with the peptidic inhibitors belonging to the serpin family, we found that cholesterol sulfate (CS), which is present at the concentration of 2.0+/-1.2 nmol/ml in human plasma, was a potent inhibitor of both plasma thrombin and plasmin. Thrombin, as determined both using a chromogenic substrate and the natural substrate, fibrinogen, was inactivated upon reaction with CS in a dose-dependent manner, but not in the presence of the structurally related steroid sulfates, I3SO3-GalCer and II3NAalpha-LacCer, suggesting that both the sulfate group and the hydrophobic side chain of CS are necessary for the inhibitory activity of CS. Preincubation of thrombin with CS at 37 degrees C for 10 min was required to achieve maximum inhibition, and virtually complete inhibition was achieved at a molar ratio of CS to thrombin of 18:1. CS-treated thrombin had the same Km and a lower Vmax than the original enzyme, and a higher molecular weight. The molecular weight and activity of the original enzyme were not observed on the attempted separation of the CS-treated enzyme by gel permeation chromatography and native PAGE, indicating that the inactivation of thrombin by CS is irreversible. In contrast, CS was readily liberated from the enzyme by SDS-PAGE, suggesting that hydrophobic interactions are involved in the CS-mediated inactivation of thrombin. When acidic lipids were reacted with thrombin after dissolving them in DMSO, I3SO3-GalCer, steroid sulfates and II3NAalpha-LacCer, as well as CS, but not SDS and sodium taurocholate, exhibited inhibitory activity, probably due to micellar formation facilitating interaction between thrombin and negatively charged lipids. On the other hand, plasmin, as determined using a chromogenic substrate, was more susceptible to acidic lipids than thrombin. CS, I3SO3-GalCer and II3NAalpha-LacCer, all of which are present in serum, inhibited the activity of plasmin in aqueous media, as well as in DMSO-mediated lipid solutions. Thus, acidic lipids in plasma were demonstrated to possess regulatory activity as endogenous detergents toward both enzymes for blood clotting and fibrinolysis.

Coexpression of cholesterol sulfate and cytokeratin as tumor markers in well-differentiated squamous cell carcinoma of the human uterine cervix

The expression of cholesterol sulfate (CS) is known to increase during squamous differentiation of keratinocytes and to activate the epsilon, eta, and zeta forms of protein kinase C as a signal transduction molecule for the subsequent expression of transglutaminase-1 (TG-1) and cytokeratins. To gain further insight into the regulation of cellular differentiation and tumorigenesis by CS, we examined the concentration and the potential for synthesis of CS in seven and four surgical specimens from human ovarian and uterine cervical cancer patients, respectively, and eight cell lines established from human uterine cervical cancer patients and compared them for the rate of expression of cytokeratin. CS was present in all of the uterine cervical cancer tissue specimens but only in the mucinous type of cystadenocarcinoma among ovarian cancer tissue specimens, and cytokeratin was highly expressed in the tissues with a high concentration of CS, which were classified as well-differentiated on the basis of morphological examination. Similarly, cells derived from a keratinizing type of well-differentiated cervical carcinoma demonstrated strong potential for synthesis of CS, stained positive with anti-cytokeratin antibody, and exhibited a higher specific activity of TG-1, whereas the cells without CS did not stain positive with anti-cytokeratin antibody and exhibited a lower specific activity of TG-1. These findings indicate that CS is coexpressed with TG-1 and cytokeratin in the well-differentiated types of squamous cell cancers as a tumor marker.

Alterations in cholesterol sulfate and its biosynthetic enzyme during multistage carcinogenesis in mouse skin

Recent evidence suggests that cholesterol sulfate may be an important second messenger involved in signaling epidermal differentiation in skin. The activity of cholesterol sulfotransferase (Ch-ST) is increased during squamous differentiation of keratinocytes and is believed to be a marker enzyme for terminal differentiation. The primary objective of this study was to examine changes in levels of cholesterol sulfate (CS) and activity of its biosynthetic enzyme, Ch-ST, during multistage carcinogenesis in mouse skin. Using SENCAR mice, we determined the activity of Ch-ST in normal epidermis, in tumor promoter-treated epidermis, in epidermis during wound healing, and in mouse skin tumors generated by initiation-promotion regimens. A single topical application of tumor promoters led to significantly elevated levels of Ch-ST activity and of CS. Epidermal Ch-ST activity was also elevated during wound healing. Dramatic increases in CS levels and in the activity of Ch-ST were found in nearly all of the papillomas and squamous cell carcinomas examined. The increased levels of CS and activity of Ch-ST in tumor promoter-treated epidermis were accompanied by increased transglutaminase-I activity. In contrast, transglutaminase I activity was not elevated in primary papillomas or squamous cell carcinomas. Finally, Ch-ST activity was significantly elevated in the epidermis of newborn HK1.ras transgenic mice, whereas transglutaminase I activity did not correlate with Ch-ST activity in these mice. These results demonstrate that diverse tumor-promoting stimuli all produce elevated CS levels and Ch-ST activity and that CS levels and Ch-ST activity were constitutively elevated in both papillomas and squamous cell carcinomas. The data also suggest a mechanism for upregulation of Ch-ST in skin tumors involving activation/upregulation of Ha-ras.

Selection of human ovarian carcinoma cells with high dissemination potential by repeated passage of the cells in vivo into nude mice, and involvement of Le(x)-determinant in the dissemination potential

Cells of the human tumor cell line RMG-1, derived from a clear-cell adenocarcinoma of the ovary, were injected intraperitoneally into nude mice, and the cells obtained from the tumor nodules in the mesenterium were found to form a larger number of, and larger-sized, tumor nodules than the original RMG-1 cells. The RMG-1-h cells, transferred into culture from the tumor nodules after a 4th in vivo passage, showed a dissemination potential as high as that of cells disseminating directly from the tissues, and exceedingly higher than that of RMG-1 cells. To assess the molecular bases of the different biological properties of RMG-1 and RMG-1-h cells, we compared the content and expression of various carbohydrate antigens in both cells. The chromosomal profile of RMG-1-h cells revealed their human origin and was identical to that of the original RMG-1 cells. In contrast to the broad histogram for the Le(x)-bearing cells among RMG-1 cells in flow cytometry, the weakly and moderately positive cells toward anti-Le(x) antibody were found to be eliminated from the histogram for the RMG-1-h cells, resulting in the enrichment of cells strongly expressing Le(x), which may account for the high dissemination potential. In addition, the adhesion of RMG-1 cells to mesothelial cells was found to be significantly inhibited by pretreatment of the cells with anti-Le(x) antibody, indicating Le(x)-mediated cell-to-cell interaction between ovarian cancer cells and mesothelial cells. By TLC-immunostaining, two Le(x)-glycolipids, III3Fuc alpha-nLc4Cer and V3Fuc alpha-nLc6Cer were detected in both RMG-1 and RMG-1-h cells, and their total concentrations were not significantly different from each other. However, the hydrophobic moieties of Le(x)-glycolipids in RMG-1-h cells were different from those in RMG-1 cells, suggesting that a difference in the structure of the hydrophobic moieties of Le(x) is partly involved in the enhanced reactivity of RMG-1-h cells toward anti-Le(x) antibody. Thus, the high dissemination potential of ovarian cancer cells was shown to be mediated by the Le(x)-determinant and the Le(x)-bearing cells are enriched by repeated in vivo passage of the cells into nude mice.

Decreased membrane fluidity and unsaturated fatty acids in Niemann-Pick disease type C fibroblasts

Niemann-Pick disease type C (NP-C) is an autosomal recessive disorder characterized by the sequestration and trapping of endocytosed cholesterol in lysosomes. The NPC1 gene on chromosome 18 was recently identified but its physiological function remains unknown. We have studied the lipid compositions of cultured human NP-C fibroblasts and mouse SPM-3T3 cell line derived from the C57BL/KsJ NP-C model mouse, which belongs to the same complementation group. Fibroblasts derived from apparently normal age-matched individuals and a subline of SPM-3T3 cells which restores cholesterol metabolism by transfer of human chromosome 18 were used as controls. Levels of free cholesterol in whole cell homogenates increased about 1.5-fold in human NP-C fibroblasts and mouse SPM-3T3 cells, while in the plasma membrane, cholesterol content did not significantly change in NP-C fibroblasts but rather decreased in SPM-3T3 cells. The total phospholipid content did not significantly change; however, among phospholipid head groups, increases in sphingomyelin and decreases in other classes were observed in human NP-C fibroblasts and mouse SPM-3T3 cells. The ratios of saturated fatty acids to unsaturated fatty acids increased in both human and mouse cells. The increase was also confirmed in the plasma membrane fraction of SPM-3T3 cells. Membrane fluidity was examined using a 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescent probe. The DPH anisotropy values were markedly increased in NP-C fibroblasts and in SPM-3T3 cells. The results suggest that a NP-C mutation causes complex alterations in cellular lipid contents and biophysical properties of the membrane.

Immunohistochemical study of sulfatide expression in gastric carcinoma: alteration of sulfatide expression

Immunohistochemical staining using a specific monoclonal antibody against sulfatide was performed to examine cellular localization of sulfatides in normal human gastric mucosa and in various types of gastric carcinoma. In normal gastric mucosa without Helicobacter pylori infection, both epithelial and glandular cells were densely stained with anti-sulfatide antibody. Sulfatide staining was more abundant in the apical area of normal epithelium compared with cytosol or basolateral areas. This tendency was stronger in the antrum than the gastric body and was more intensified in glandular cells of the pyloric glands. The levels of sulfatide expression were decreased in papillary and well-differentiated adenocarcinomas compared with normal mucosa, were markedly attenuated in moderately differentiated adenocarcinomas, and were very low in poorly differentiated adenocarcinomas. The polarity of the stains was preserved in gastric cancers that exhibited differentiated tissue organization. The levels of sulfatide expression were highly variable in signet ring carcinoma cells. The cancer cells that expressed sulfatides did not show any polarity of staining.

Inhibition of pancreatic elastase by sulfated lipids in the intestinal mucosa

Sulfated lipids, cholesterol sulfate (CS) and I3SO3-GalCer, are commonly present in the epithelia of the digestive tracts of pigs, humans, rabbits, and rats. CS was the only sulfated lipid in the esophageal epithelia of these mammals, and I3SO3-GalCer, together with CS, was detected in the epithelia of the gastrointestinal tracts, at a concentration higher than 0.05 micromol per gram of dry weight. Although no sulfated lipids were present in the pancreatic duct, they were found in relatively high concentrations in the duodenal, jejunal, and ileal epithelia. To elucidate the functional significance of sulfated lipids in the digestive tract, we determined the effect of CS and I3SO3-GalCer on the activities of pancreatic and Pseudomonas aeruginosa elastases and found that both characteristically inhibited the pancreatic elastase but not the P. aeruginosa elastase. Desulfation of CS and I3SO3-GalCer abolished their inhibitory activity, and other membrane constituents including free fatty acids, phospholipids, and gangliosides failed to inhibit pancreatic elastase. In addition, steroid sulfates, such as dehydroepiandrosterone sulfate and pregnenolone sulfate, did not exhibit any inhibitory activity toward pancreatic elastase, indicating that the sulfate group and a suitable hydrophobic side chain are required in the inhibition of elastase. Inhibition of elastase by sulfated lipids occurred in a dose-dependent manner, and the molar ratios of CS and I3SO3-GalCer to elastase at which the enzyme activity was inhibited to 50% of the maximum level were 6:1 and 9:1, respectively. CS-treated elastase had the same Km and a lower Vmax compared with the untreated enzyme, and sulfated lipids were observed to bind tightly to the enzyme, suggesting irreversible inhibition. Thus, CS and I3SO3-GalCer in the digestive tracts of mammals were shown to function as epithelial inhibitors of pancreatic elastase.

Alteration of acidic lipids in human sera during the course of pregnancy: characteristic increase in the concentration of cholesterol sulfate

In this study, we determined the concentrations of acidic lipids, including cholesterol sulfate (CS), sulfatide and GM3 ganglioside, in human sera of non-pregnant state and during the course of pregnancy. In human sera of non-pregnant women, GM3 was present at a concentration of 8 nmol/ml and the concentrations of CS and sulfatides were less than 20% of that of GM3. The concentration of sulfatides in sera at the second trimester of gestation was decreased, but CS gradually increased from the first to the third trimester of gestation with a correlation coefficient of 0.66, and a correlation between the concentration of CS and weeks of gestation (p<0.01). CS was also contained in the placental villi, and its concentration increased from the first to the third trimester of gestation, suggesting that placental CS is one of the source of CS in the blood by shedding.

Sulfated lipids as inhibitors of pancreatic trypsin and chymotrypsin in epithelium of the mammalian digestive tract

Cholesterol sulfate and I3SO3-GalCer, which were commonly contained in the epithelia of mammalian digestive tracts, were found to inhibit the activities of typical digestive enzymes, pancreatic trypsin and chymotrypsin, but steroid sulfates, gangliosides and the other membrane constituents did not show any inhibitory activity. The preincubation of trypsin with I3SO3-GalCer at 37 degrees C for 10min was necessary to inhibit the activity of trypsin, but cholesterol sulfate showed its inhibitory activity without preincubation. Sulfated lipid-treated enzyme gave the same Km as and lower Vmax than those of the original enzymes. Also, both sulfated lipids inhibited pronase from Streptomyces griseus, but not lysyl endopeptidase from Achromobacter lyticus. These findings indicate that cholesterol sulfate and I3SO3-GalCer in the digestive tract function as epithelial inhibitors to prevent tissue injury by endogenous and exogenous proteases.

High expression of uridine diphosphate-galactose: Lc3Cer beta 1-3 galactosyltransferase in human uterine endometrial cancer-derived cells as measured by enzyme-linked immunosorbent assay and thin-layer chromatography-immunostaining

We have developed a new procedure for the selective determination of beta 1-3 and beta 1-4 galactosyltransferases with Lc3Cer as the substrate and the microsomes of fetal and adult porcine livers as the enzyme sources. This method was based on the detection of such products as Lc4Cer for beta 1-3 galactosyltransferase (beta 1-3GT) and nLc4Cer for beta 1-4 galactosyltransferase (beta 1-4GT), with monoclonal anti-Lc4Cer and anti-nLc4Cer antibodies, respectively. This method thus enabled us to differentiate the activity of beta 1-3GT from that of beta 1-4GT with a high degree of sensitivity. The method was then used to determine the activities of both enzymes in human gynecological carcinoma-derived cells. Four of the five cell lines derived from uterine endometrial cancer expressed significantly high levels of specific activity of beta 1-3GT among the cell lines examined, while their beta 1-4GT activities were less than 20% of that for beta 1-3GT in the endometrial carcinoma-derived cells. On the other hand, a higher specific activity of beta 1-4GT than that of beta 1-3GT was detected in the cell lines derived from uterine cervical and ovarian cancers. These findings were thus found to correlate closely with the rate of expression of Lc4Cer- and nLc4Cer-based carbohydrate chains in the cell lines based on the results of immunohistochemical staining.

Distribution of cholesterol sulfate and its anabolic and catabolic enzymes in various rabbit tissues

Cholesterol sulfate (CS) recently has been shown to be involved in signal transduction pathway. To evaluate its functional significance, we determined the concentration of CS, and the specific activities of cholesterol sulfotransferase and CS sulfatase in various tissues of rabbit, and compared them with the concentration of sulfoglycolipids in rabbit tissues. CS was present in the epithelia and mucosa, but not in the tunica muscularis, of the digestive tract, trachea, uterine endometrium and uterine cervix. It was also present in lung, spleen, kidney, prostate, skin, hair, and nail at relatively high concentrations. Its concentration in the uterine endometrium was nine times higher in pseudopregnant rabbits than in nonpregnant rabbits because of activation of cholesterol sulfotransferase and inhibition of CS sulfatase in the pseudopregnant rabbits. Sulfoglycolipids were not detected in the uterine endometria of either non-pregnant- or pseudopregnant rabbits. However, sulfoglycolipids were detected at relatively high concentrations in the cerebrum, cerebellum, stomach, duodenum, jejunum, testis, and kidney of rabbits and thus the tissues in which both sulfolipids were detected were the gastrointestinal tract and kidney. In the digestive tract, the concentration of CS decreased in the order esophagus, stomach, duodenum, and jejunum, but that of sulfatide increased in the same order, indicating distribution of CS in the squamous epithelium. In addition, both CS and sulfatide were detected in the serum. On the other hand, CS sulfatase activity was detected in all tissues examined, even in hair, from which the enzyme was liberated by brief sonication, and its highest specific activity was detected in the liver. The specific activity of cholesterol sulfotransferase varied among the tissues examined and was found to be significantly high in the esophageal epithelium and the uterine endometrium of pseudopregnant rabbit, indicating involvement of cholesterol sulfation in the formation of epithelium.

Arthrobacter ureafaciens sialidase isoenzymes, L, M1 and M2, cleave fucosyl GM1

Among bacterial, fungal and viral sialidases, the sialidase from Arthrobacter ureafaciens has the unique property of cleaving sialic acids linked to the internal galactose of gangliotetraose. In this study, we examined the ability to cleave the internal sialic acids of GM1 and fucosyl GM1 of sialidases from several bacterial and fungal origins, including Clostridium perfringens and Vibrio cholerae. We found that A. ureafaciens sialidase could liberate the sialic acid of GM1 at the highest rate, and was the only enzyme which could cleave fucosyl GM1 among the sialidases examined. The affinity-purified sialidase derived from the culture medium of A. ureafaciens was comprised of four isoenzymes with different molecular weights and isoelectric points, the isoenzymes that cleaved fucosyl GM1 being L (88 kDa, pl 5.0), M1 (66 kDa, pl 6.2) and M2 (66 kDa, pl 5.5), but not S (52 kDa, pl 6.2) which showed the highest specific activity toward colominic acid among the four isoenzymes.

Menstrual cycle-associated regulation of anabolic and catabolic enzymes causes luteal phase-characteristic expression of sulfatide in human endometrium

OBJECTIVE

Our purpose was to investigate the metabolic background of the expression of sulfoglycolipids in human endometrium during the luteal phase.

STUDY DESIGN

We investigated the expression of sulfoglycolipids by thin-layer chromatography immunostaining and the activities of galactosylceramide sulfotransferase and arylsulfatase A, which regulate the synthesis and degradation of sulfoglycolipid. In addition, arylsulfatase A messenger ribonucleic acid was studied by reverse transcriptase polymerase chain reaction.

RESULTS

Sulfoglycolipid expression showed a marked increase in the luteal phase but not in the follicular phase, whereas sialoglycolipids remained relatively constant. The increase of sulfoglycolipids was found to be due to 4.5-fold increased activation of sulfotransferase and a concurrent reduction of arylsulfatase A activity in the luteal phase. Arylsulfatase A messenger ribonucleic acid was detected in both phases and showed no significant changes.

CONCLUSIONS

These findings suggest that increased sulfoglycolipid expression in the luteal phase is due to the simultaneous regulation of sulfotransferase and arylsulfatase A, probably by sex steroid hormones.

Expression of GalCer sulfotransferase by human uterine endometrial carcinoma cell lines

We investigated the expression of sulfoglycolipids in several gynecological cancer cell lines by metabolic labeling with S-35-sulfate as well as the activity of GalCer sulfotransferase (ST) and arylsulfatase A (ASA), enzymes which are responsible for the synthesis and degradation of sulfoglycolipids. The endometrial carcinoma cell lines expressed sulfoglycolipids and showed ST activity, indicating that increased synthesis of sulfoglycolipids due to elevated ST activity is a characteristic of endometrial carcinoma that distinguishes it from other carcinomas. These cell lines could provide a useful model for studying the functions of sulfoglycolipids as well as biological properties of ST in cancer cells.

GM1b is a new member of antigen for serum antibody in Guillain-Barré syndrome

Serum antibody from some patients with Guillain-Barré syndrome recognized an antigen of a minor component in human brain monosialoganglioside fraction. We purified that antigen, which migrated at a position slightly lower than that of GM1 on a thin-layer chromatogram (TLC), by using Iatrobeads column chromatography and preparative TLC. Structural analyses, including fast atom bombardment mass spectrometry, showed it to be GM1b. An enzyme-linked immunosorbent assay (ELISA) using purified GM1b showed that anti-GM1b antibody was present in 22 of 104 cases tested. No anti-GM1b antibody was present in the sera from control patients with other diseases or from the normal controls. Four sera recognized only GM1b among the 11 ganglioside antigens tested. The other 18 sera had antibodies to other antigens, most of which shared no terminal epitope with GM1b. Eight of nine sera samples with anti-GalNAc-GD1a antibody also had anti-GM1b antibody. Antibody to a minor monosialoganglioside, GM1b, was found to be a useful diagnostic marker for Guillain-Barré syndrome. Further study is needed to determine whether this antibody plays a role in the pathogenetic mechanism of the syndrome.

Sensitive method for the determination of pulmonary surfactant phospholipid/sphingomyelin ratio in human amniotic fluids for the diagnosis of respiratory distress syndrome by thin-layer chromatography-immunostaining

By TLC-immunostaining with the monoclonal antibody VJ-41, which preferentially reacted with sphingomyelin (Sm) and disaturated fatty acid-containing phosphatidyl choline (DSPC), Sm and surfactant phospholipid dipalmitoyl PC were only detected in the lipid extracts from human amniotic fluid. The method was useful in the selective and simultaneous determination of surfactant phospholipid and Sm concentrations in the amniotic fluids to determine the level of maturity of the lungs of the fetus. By measuring the density of spots visualized by TLC-immunostaining, we detected Sm at a sensitivity two times higher than that for dipalmitoyl PC using the antibody. More than 50 ng of dipalmitoyl PC and Sm was detected on the same TLC plate and the standard curves were linear up to 1 microgram of phospholipids. The method was applied to determine the surfactant phospholipid/Sm ratio in 20 microliter of the amniotic fluids obtained at delivery, and the amniotic fluids from the women who delivered a baby suffering from respiratory distress syndrome (RDS) were easily discriminated from the normal amniotic fluids. In an analysis of 200 microliter of amniotic fluids from 4 RDS cases and 16 normal baby cases, the mean DSPC/Sm ratios were 0.97 +/- 0.53 and 5.75 +/- 1.29, respectively.

Developmental changes of neutral glycosphingolipids as receptors for pulmonary surfactant protein SP-A in the alveolar epithelium of murine lung

A dramatic change in the glycosphingolipid composition in murine lung occurred between 1 day and 1 week after birth. GlcCer and LacCer were the predominant neutral glycosphingolipids prenatally and 1 day after birth, and the concentrations of globo- and ganglio-series glycosphingolipids increased abruptly from 1 week after birth, reaching maxima at 2-3 weeks. To explore the functional significance of the change, we examined the role of neutral glycosphingolipids as receptors for the murine pulmonary surfactant protein, SP-A, and found that SP-A bound to LacCer, Gg3Cer, and Gg1Cer, but not to Gb3Cer, Gb4Cer, IV3GalNAc alpha-Gb4Cer, sulfatide, or several gangliosides. On TLC-blotting with 125I-labeled SP-A, the binding of SP-A to Gg3Cer and Gg4Cer was 5 times higher than that to LacCer, and on immunohistochemical staining Gg4Cer and Gg3Cer was mainly observed in the alveolar epithelium. Thus, the capacity to retain SP-A of glycolipid receptors per gram dry weight of lung at 1 week after birth was 1.6 times higher than that at 1 day after birth, and reached a maximum 3 weeks after birth. These findings suggest that the enhanced synthesis of the ganglio-series neutral glycosphingolipids 1 week after birth results in an increase in the binding capacity for SP-A on the epithelial cell surface of alveoli.

Selective reduction in alpha-hydroxypalmitic acid-containing sphingomyelin and concurrent increase in hydroxylated ceramides in murine skin tumors induced by an initiation-promotion regimen

The sphingomyelin cycle is activated to accumulate ceramides in the process of epidermal differentiation. We found that sphingomyelin in the epidermis of 4 different murine strains gave three bands on TLC, the lower band containing alpha-hydroxypalmitic acid (C16h:0(alpha)). However, in the papillomas induced in the skin of SENCAR and SSIN mice by initiation with 7,12-dimethylbenz[a]anthracene followed by promotion with 12-O-tetradecanoylphorbol acetate, the concentration of C16h:0(alpha)-containing sphingomyelin was selectively diminished with a concomitant increase in the concentrations of the ceramides containing alpha-hydroxy fatty acids. These findings indicate a possible involvement of the selective hydrolysis of alpha-hydroxy fatty acid-containing sphingomyelin in the process of tumorigenesis in mouse skin.

Role of sulfatides in adhesion of Helicobacter pylori to gastric cancer cells

We have demonstrated that clinical isolates of Helicobacter pylori preferentially bind to sulfatides (I3SO3-GalCer) and GM3 gangliosides (II3NeuAcLacCer), two predominant acidic glycosphingolipids in the human gastric mucosa, on thin-layer chromatography plates. However, it has not yet been clarified that these glycospingolipids truly serve as adhesion receptors for H. pylori in live cells. In this study, we used a gastric cancer cell line, KATO III, as a cellular model of H. pylori adhesion and examined the role of sulfatides in attachment. The adhesion of H. pylori (i.e., a standard strain of H. pylori, NCTC 11637) to KATO III cells and the effects of various substances on this adhesion were monitored and semiquantitated by flow cytometric analysis. Sulfated glycoconjugates, such as heparin and gastric mucin, significantly inhibited H. pylori adhesion to KATO III cells. Membrane preparations from KATO III cells strongly inhibited this adhesion. In the membrane preparations, sulfatides were present as a major acidic glycosphinoglipid. With the exception of sulfatides, no distinct adhesion of H. pylori to glycospingolipids from KATO III cells were observed. Moreover, H. pylori did not bind to any membrane proteins of KATO III cells. Finally, a monoclonal anti-sulfatide antibody markedly reduced H. pylori adhesion to KATO III cells. These results suggest that sulfatides, and possibly related sulfated compounds, serve as a major receptor for cell adhesion by H. pylori.

IgM natural antibody against an asialo-oligosaccharide, gangliotetraose (Gg4), sensitizes HIV-I infected cells for cytolysis by homologous complement

Although cells are usually resistant to homologous complement, the IgM antibody against gangliotetraose (Gg4), an asialo-oligosaccharide of GM1, was found to cause cytolysis of HIV-1 infected cells by homologous complement. Due to its size, IgM might enable the initiation of the complement cascade away from membrane complement inhibitors such as decay accelerating factor and membrane cofactor protein. Furthermore, HRF20 (CD59), which restricts formation of membrane attack complexes (MAC) of complement on homologous cell membranes, was significantly decreased on HIV-infected cells and therefore formation of MAC on cell membranes would be facilitated. IgM antibodies reactive with HIV-infected cells could result in the elimination of infected cells via complement-mediated cytolysis in HIV-infected patients, since all tested sera from HIV-positive hemophilia patients who have survived for >12 years contained IgM antibody activity against HIV-infected MOLT4 cells in a preliminary experiment. Therefore, administration of IgM antibodies reactive with HIV-infected cells may be effective in the treatment of HIV carriers.

Significantly high synthetic activities of cholesterol sulfate in the nasal, oral and tracheal mucosae of guinea pigs

Cholesterol sulfate (CS) is widely distributed in mammalian tissues and various physiological roles for it have been suggested, but the presence of CS in the nasal tissues has not yet been reported. This is the first report in which the CS content and the activity of its regulatory enzymes, cholesterol sulfotransferase (CST) and cholesterol sulfate sulfatase (CSS), in the nasal mucosa of the guinea pig were examined and compared with those in the oral and tracheal mucosae. The highest concentration of CS was detected in the oral mucosa and the second highest in the nasal mucosa. The activity of CST was also highest in the oral mucosa and the second highest in the nasal mucosa. On the other hand, that of CSS was highest in the tracheal mucosa. The accumulation of CS is assumed to be related to squamous differentiation, because the activity of transglutaminase type 1 in the nasal, oral and tracheal mucosae coincided with the order of the concentration of CS in those tissues. These results suggested that the accumulation of CS is correlated with the morphological differences between the oral stratified squamous and the nasal or tracheal pseudostratified epithelium, and furthermore that the nasal epithelium is more susceptible to squamous metaplasia than the tracheal epithelium in the guinea pig.

Alteration in the reactivity of sphingomyelin in mitogen-stimulated lymphocytes

The antigens for a monoclonal antibody, VJ-41, established by alloimmunization of B10.A(3R) mice with lymphocytes from B10.A(5R) mice and screening of its reactivity toward Con A-stimulated human T lymphocytes, were found to be phosphorylcholine-containing ceramides (sphingomyelin) and disaturated fatty acyl glycerol (phosphatidyl-choline, PC), but neither deacylated sphingomyelin nor unsaturated fatty acid-containing PC reacted with the antibody. Although the reactivity of disaturated fatty acyl PC increased with increasing chain length, that of sphingomyelin was stronger than that of di-20:0-PC. The binding of the antibody to Con A-stimulated lymphocytes was inhibited by sphingomyelin-containing liposomes, but not by di-18:0-PC-containing ones, and the concentration of sphingomyelin in Con A-stimulated human T-lymphocytes was the same as that in non-stimulated ones, indicating that the reactivity of sphingomyelin in lymphocytes is altered by Con A-stimulation.

Enhancement of adhesive property of epithelial cell line Mm2T by culture in the presence of methylated vitamin B12

A thymic epithelial cell line Mm2T was cultured in a medium containing a high concentration (100 micrograms/ml) of methylated vitamin B12 (CH3-B12). After 19 days, cells were found to have a flat phenotype, to have lost the floating cells which were observed in the control cells at the confluent stage, and to have acquired a resistance to trypsin. However, treatment of the CH3-B12-treated cells with EDTA resulted in a dissociation of cell-to-cell contact and reaggregation was achieved by addition of Ca2+, indicating the involvement of Ca2+ ion in cell-to-cell contact. Electron microscopic analyses revealed that the CH3-B12-treated cells were nearly square in their vertical section, which was in contrast to the dome-shaped feature of the control cells, and their cell-to-cell contact area was significantly widespread, as compared to those of the control, indicating that Mm2T cells acquires an adhesive property by treatment with CH3-B12. Biochemical analyses of both cells indicated that the concentration of glucosylceramide in the CH3-B12-treated cells was higher than that of the control. Free glucose characteristically inhibited the reattachment of cells dissociated with EDTA, suggesting the involvement of glucose in the cell-to-cell adhesion of CH3-B12-treated cells. In addition, WGA-binding glycoconjugates were intensely observed in the boundary region of CH3-B12-treated cells by immunohistochemical staining, but not in that of the control cells. It is suggested that CH3-B12 may affect the morphological alteration of Mm2T by enhancing cell adhesion through elevated expression of the C-type lectin.

Characteristic expression of GD1 alpha-ganglioside during lactation in murine mammary gland

Cellular proliferation and differentiation in mammary gland are known to be significantly altered during pregnancy and subsequent lactation. To characterize the different stages of mammary gland during pregnancy and lactation, we analyzed the glycosphingolipid compositions in the mammary gland of DDD and ICR mice at several periods of pregnancy and lactation, and found that the ganglioside composition, but not neutral glycosphingolipids, was characteristically altered during the pregnancy and lactation periods. The concentrations of acidic glycosphingolipids, I3SO3-GalCer 1, GM3, GM1a, GM1b and GD1a, were reduced during the course of pregnancy and lactation. GD1 alpha (III6NeuAc alpha,IV3NeuAc alpha-Gg4Cer) was first detected at the mid-period of pregnancy (12 days of pregnancy for ICR mice), increased in concentration at the late-period of pregnancy (GD1 alpha concentration was 100 times higher at 18 days than that at 12 days of pregnancy), and was a major ganglioside comprising 60-70% of the total lipid-bound sialic acid in the mammary gland of ICR and DDD mice at the lactation period, indicating that expression of GD1 alpha is associated with the lactating mammary gland of mice. In fact, GD1 alpha was highly concentrated in the milk fat globule, in which it was a major component.

Programmed expression of cholesterol sulfotransferase and transglutaminase during epidermal differentiation of murine skin development

To clarify the role of cholesterol sulfate (CS) in the process of epidermal differentiation in vivo, we investigated the concentration of CS and the specific activities of cholesterol sulfotransferase (CST), cholesterol sulfate sulfatase (CS sulfatase) and epidermal transglutaminase (ETG) in murine skin in the pre- and postnatal periods. In the skin at day 14 of gestation, CS was not detected with TLC and the specific activities of all the enzymes were low. However, concomitant with the formation of the multilayered structure of the epidermis (at day 16), the specific activities of CST steeply increased. Although the insoluble CS sulfatase in the microsomal fraction remained at a relatively constant level, the soluble CST in the cytosol fraction showed a 6-fold increase from day 14 to day 16, and the activity decreased continuously in the following period, reaching one forty-sixth of the maximum level at 4-months-old mice. Reflected by the increase in activity, CS was detected in fetal skin at day 15, and the concentration in epidermis significantly increased during the gestation period, reaching maximum level at day 17. Furthermore, the changes in the concentration of cholesterol sulfate were identical with those of N-(O-linoleoyl)-omega-hydroxy fatty acyl sphingosine and its glucosyl derivative in the epidermis. On the other hand, the specific activity of ETG increased after birth. Thus, the activation of CST and ETG was shown to occur separately in association with the formation of the multilayered structure and thickening of the stratum corneum, respectively.

Cholesterol sulfate, a novel activator for the eta isoform of protein kinase C

Activity of protein kinase C depends on the interaction with polar head-groups of two membrane lipids, i.e., phosphatidylserine and diacylglycerol. In the present study, we demonstrated a novel activation mechanism of the eta isoform of protein kinase C (nPKC eta), which is predominantly expressed in epithelial tissues in close association with epithelial differentiation. We found that the nPKC eta was activated by cholesterol sulfate, a metabolite of cholesterol formed during squamous differentiation. This activation was greater than that by phosphatidylserine plus phorbol ester; the Vmax for the activation by cholesterol sulfate was 3.6 times that by phosphatidylserine plus phorbol ester, while Kms were almost equal. In the presence of cholesterol sulfate, phorbol ester only weakly enhanced the activity of nPKC eta. Activation of nPKC eta by cholesterol sulfate was further demonstrated by autophosphorylation of the kinase molecule. However, the alpha and delta isoforms of protein kinase C were not activated by cholesterol sulfate. The present observation affords a new insight into a signal transduction pathway of squamous differentiation.

Pseudopregnancy-dependent accumulation of cholesterol sulfate due to up-regulation of cholesterol sulfotransferase and concurrent down-regulation of cholesterol sulfate sulfatase in the uterine endometria of rabbits

The uterine endometria of rabbits induced into pseudopregnancy by intramuscular injection of 17 beta-estradiol, followed by intravenous injection of human chorionic gonadotropin, expressed cholesterol sulfate at a significantly high concentration. The highest concentration of cholesterol sulfate was observed 4 days after the injection of gonadotropin for formation of the corpus luteum, being 10 times higher than that in nonpregnant endometria, and 15.2% of the total cholesterol in the endometrium was converted to the sulfated form, whose percentage in nonpregnant endometrium was 3.2%. However, no significant change in the concentration of gangliosides was observed during the period of pseudopregnancy. In the pseudopregnant endometria, the activity of cholesterol sulfotransferase, a cytosolic thiol enzyme, was increased thirtyfold over that in the nonpregnant endometria, whereas cholesterol sulfate sulfatase, a microsomal enzyme, exhibited approximately one-tenth of the activity in nonpregnant endometria. Arylsulfatase C, but not arylsulfatases A and B, exhibited the same change in activity as cholesterol sulfate sulfatase. Thus, the striking increase in cholesterol sulfate after induction of pseudopregnancy was found to be due to the activation of cholesterol sulfotransferase and the simultaneous inhibition of cholesterol sulfate sulfatase.

Unique T cell differentiation markers: gangliosides with cholera toxin receptor activity on murine fetal thymocytes

Cholera toxin B subunit receptors (CTBR; gangliosides GM1a and GM1b-GalNAc-Gal) and GM1b-type gangliosides were examined during T cell development in BALB/c mice by FACS or TLC immunostaining. Sixty-two percent of CD4-8- early fetal thymocytes express CTBR [58% low affinity (GM1a+), 4% high affinity (GM1a2+)] at 13 days gestation (Day 13); GM1a2+ was expressed preferentially on Thy-1+ fetal thymocytes after Day 13. GM1a2+ Thy-1+ cells increased from 4% on Day 13 to 95% on Day 17. Surface GM1a2+ decreased beginning on Day 15 while GM1b-GalNAc-Gal (and CD4 and CD8) increased. GM1b-type+ cells increased from 8% on Day 13 to 51% on Day 17 and then decreased to 16% at 4 weeks; few asialo GM1+ cells (< 5%) are seen during gestation. Thus, synthesis of GM1a- and GM1b-type series was active until Days 15 and 17, respectively, and then was suppressed; GM1b-GalNAc-Gal was synthesized from GM1b following Gestational Day 15. GM1a- and GM1b-type identify immature T cells in mice, while GM1b-GalNAc-Gal identifies mature T cells.

Hormone-dependent enhancement in binding of oto- and nephrotoxic aminoglycoside antibiotics

Intraperitoneal administration of gentamicin (40 mg/ml) to the guinea pig is known to cause damage of the tissue of the kidneys and auditory organs. By indirect immunohistochemical staining with anti-gentamicin antiserum, those cells with high affinity to gentamicin in the auditory organs and kidneys were the hair cells in the cochlea and the epithelial cells in the renal tubules. The concentrations of gentamicin in the serum and perilymph of the guinea pig with tissue damage were found to be 2 and 0.6 mg/ml at the maximal levels, respectively, by high performance liquid chromatography. The same concentration of gentamicin, 2 mg/ml, also inhibited cell growth and resulted in cell damage of the renal tubule-derived cell lines, JTC-12 and MDCK. Among the antibiotics examined, i.e. streptomycin, gentamicin, fradiomycin and kanamycin, gentamicin showed the strongest effect on growth inhibition of the renal tubule-derived cells, when these cells were cultured in a medium with 5% fetal calf serum. Although the number of JTC-12 cells in the medium without fetal calf serum remained the same for a week, even with the addition of either gentamicin (0.5 mg/ml) or parathyroid hormone (2 mM) the coadministration of gentamicin and parathyroid hormone resulted in a loss of cells due to cellular death, and the amount of gentamicin bound onto the cells cultured with gentamicin plus parathyroid hormone was significantly higher than that with gentamicin alone. These results indicate that the expression of the receptor for gentamicin on the cell surface is greatly enhanced by hormonal stimulation.

Compensatory occurrence of IV2Fucalpha,II3NeuAcalpha-Gg4Cer and human fetal antigen Lc4Cer in small cell carcinomas of the human lung

By means of a thin-layer chromatography immunostaining procedure involving a human monoclonal anti-Lc4Cer antibody, which was established by hybridizing murine myeloma cells and human lymphocytes from a cancer patient, Lc4Cer was proven to be a fetal antigen of human lung and to be a cancer-related antigen in small cell carcinomas of human lung, but not of other lung cancers, i.e., large cell carcinomas, adenocarcinomas, and squamous carcinomas. With the simultaneous detection of IV2Fuc alpha,II3NeuAc alpha-Gg4Cer with rabbit anti-IV2Fuc alpha,II3NeuAc alpha-Gg4Cer antiserum, the expression of Lc4Cer and IV2Fuc alpha,II3NeuAc alpha-Gg4Cer was found to be compensatory and, consequently, small cell lung carcinomas could be classified into Lc4Cer- and IV2Fuc alpha,II3NeuAc alpha-Gg4Cer-expressing types, L-SCLC and F-SCLC, respectively, which were detected in four and 27 of 31 patients' tissues and in one and three of four nude mouse-transplanted small cell lung carcinoma tissues, respectively. The compensatory expression of Lc4Cer and IV2Fuc alpha,II3NeuAc alpha-Gg4Cer in small cell carcinomas indicated that different metabolic pathways for glycosphingolipids were activated to give the distinct glycosphingolipid compositions in the two types of small cell lung carcinomas.

Luteal phase-characteristic induction of I3SO3-GalCer in human cervical epithelia and uterine endometria, and follicular phase-characteristic formation of a ganglioside-derived negative charge gradient in different regions of fallopian tubes

In a series of experiments on the hormone-dependent molecular alteration in the human genital tract during the menstrual cycle, we focused our attention on a change in the negative charge due to the sulfuric acid- and sialic acid-containing glycosphingolipids. Although a ganglioside-derived negative charge was maintained in the cervical epithelia and uterine endometria at a relatively constant concentration throughout the luteal and follicular phases, I3SO3GalCer in both tissues characteristically increased in the luteal phase, indicating that the synthesis of I3SO3-GalCer in both tissues is associated with the menstrual cycle. However, I3SO3-GalCer in mucosae of the fallopian tubes in both phases was present in a concentration similar to that in the uterine endometrium in the luteal phase, and the change in the concentration did not associated with the menstrual cycle. On the other hand, although the concentrations of I3SO3-GalCer and II3NeuAc-LacCer, a major ganglioside, were similar in different regions, that is, the isthmus, ampulla and fimbriae of the fallopian tubes in the luteal phase, II3NeuAc-LacCer was present in a gradually increasing concentration from the isthmus to the fimbriae in the follicular phase, giving a gradually decreasing ratio of I3SO3GalCer to ganglioside from the uterus to the fimbriae. These findings indicate that the metabolism of sulfo- and sialoglycosphingolipids in the human genital tract is strictly controlled by estrogen and progesterone.

Immunoglobulin variable region sequences of two human monoclonal antibodies directed to an onco-developmental carbohydrate antigen, lactotetraosylceramide (LcOse4Cer)

A human monoclonal antibody, 11-50, was generated and was shown to recognize an onco-developmental carbohydrate antigen, LcOse4Cer. The isotype of this antibody was IgM, lambda, similar to the previously known human anti-LcOse4 antibodies, such as IgMWOO and HMST-1. We raised a murine anti-idiotypic antibody G3 (IgG1, kappa) against 11-50, and tested its reactivity towards the affinity purified human polyclonal anti-LcOse4 antibodies prepared from pooled human sera using a Gal beta 1-->3GlcNAc beta-immobilized column. The results indicated that at least a part of the human polyclonal anti-LcOse4 antibodies shared the G3 idiotype with 11-50. We further analyzed the sequence of variable regions of the two anti-LcOse4 antibodies, 11-50 and HMST-1. Sequence analysis of the heavy chain variable regions indicated that the VH regions of these two antibodies were highly homologous to each other (93.5% at the nucleic acid level), and these antibodies utilized the germline genes VH1.9III and hv3005f3 as the VH segments, which are closely related germline genes of the VHIII family. It was noted that these germline VH genes are frequently utilized in fetal B cells. The JH region of both antibodies was encoded by the JH4 gene. For the light chain, the V lambda segments of the two antibodies were 96.3% homologous to each other at the nucleic acid level. The V lambda segments of both antibodies showed the highest homology to the rearranged V lambda gene called V lambda II.DS among reported V lambda genes, while the exact germline V lambda genes encoding the two antibodies were not yet registered in available sequence databanks. The amino acid sequences of the J lambda segments of both antibodies were identical. These results indicate that the two human antibodies recognizing the onco-developmental carbohydrate antigen Lc4 are encoded by the same or very homologous germline genes.

Systematic analysis of glycosphingolipids in the human gastrointestinal tract: enrichment of sulfatides with hydroxylated longer-chain fatty acids in the gastric and duodenal mucosa

The composition of the glycosphingolipids of the human gastrointestinal tract was studied. The major neutral glycosphingolipids were ceramide monohexosides (e.g., GalCer, GlcCer), LacCer, Gb3Cer, Gb4Cer and more polar ones with more than four sugars, whereas neither Gg3Cer nor Gg4Cer were present. The acidic glycosphingolipids consisted of sulfatides and gangliosides such as GM3, GM1, GD3 and GD1a. Also a large amount of sulfatides was found in the gastric mucosa and duodenum. The concentrations of sulfatides in the fundic mucosa, antral mucosa and duodenum amounted to 416.0, 933.8 and 682.9 nmol/g of dry weight, respectively, exceeding those in the gastric mucosa and kidney of other mammals. The major molecular species of the sulfatides were identified as I3SO3-GalCer with hydroxylated longer-chain fatty acids based on the analyses by gas-liquid chromatography and negative ion fast-atom bombardment mass spectrometry. In contrast, gangliosides in these regions showed a tendency to be lower than sulfatides, and the molar ratios of sulfatides to gangliosides were about 2.0, whereas those in other parts were less than 0.5. A high content of sulfatides in the gastric and duodenal mucosa, where mucosa is easily insulted by acid, pepsin and bile salts, may be closely related to their roles in mucosal protection.

Characteristic alteration in the concentration of IV 3NeuAc alpha-nLc4Cer in the villi of human placenta during the gestational period

A study on the ganglioside composition in the villi isolated from human placenta at various gestational periods was carried out by conventional procedures including thin-layer chromatography (TLC), TLC-immunostaining, negative ion fast-atom bombardment mass spectrometry (FABMS) and exoglycosidase treatment. The major gangliosides in the villi were II3 NeuAc-LacCer (GM3) and IV3NeuAc alpha-nLc4Cer, comprising 60-70% of the total gangliosides. The concentration of IV3NeuAc alpha-nLc4Cer per gram dry weight of tissue in the villi was found to be gradually decreased from the early to the late gestational period and the molecule with 2-hydroxy fatty acids was undetectable after 20 weeks of the gestational period. However, no significant correlation between the concentration of GM3 and the gestational periods was observed. Thus the characteristic alteration in the concentration of IV3NauAc alpha-nLc4Cer in the villi might be related to various functions of human placental villi during the gestational period.

Human cervical epidermal carcinoma-associated intracellular localization of glycosphingolipid with blood group A type 3 chain

A monoclonal antibody, MRG-1, was produced by immunizing a mouse with a human ovarian mucinous cyst adenocarcinoma-derived cell line, RMUG-L. By immunohistochemical staining, the antigen was found to be exclusively localized in the intracellular structures of the cells used as the antigen and of the epithelial cells in normal human cervical glands. However, although the antigen was predominantly detected in the plasma membrane and the intercellular structure of the middle layer of normal human cervical squamous epithelium (92%), it was also contained in the intracellular structure of cervical epidermal carcinoma at a high frequency (80%). The striking difference in the distribution of the MRG-1 antigen between normal and cancerous tissues was found to be a cervical carcinoma-associated phenomenon and a useful tumor marker for immunohistochemical examination. Since the antigen was found to be of a blood group A-related nature by immunohistochemical staining of the tissues and to be a glycosphingolipid, it was purified from human erythrocytes of blood group A, and the structure was concluded to be GalNAc alpha 1-3Gal(2-1 alpha Fuc)beta 1-3GalNAc alpha 1-3Gal(2-1 alpha Fuc)-beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1' Cer, blood group A type 3 chain-containing glycosphingolipid, by NMR, negative ion FABMS and permethylation analysis. In the subcellular localization analysis of the antigen, type 3-A glycosphingolipid antigen was detected in the Golgi body and the microsomes of RMUG-L cells, and the distribution coincided with the finding by immunohistochemical staining. In addition, in cervical epidermal carcinoma, although the blood group A, mainly type 2-A chain, was localized in the plasma membrane and the intercellular structure, the blood group A type 3 chain was selectively found in the perinuclear structure. Also, the blood group A type 3 chain in cervical dysplasia as well as that in normal cervix was predominant in the plasma membrane. Thus, the selective intracellular localization of blood group A type 3 chain was a phenomenon characteristic of cervical epidermal carcinoma and the carcinoma in situ.

Structural characteristics of the ceramides of neutral glycosphingolipids in the human female genital tract--their menstrual cycle-associated change in the cervical epithelium and uterine endometrium, and their dissociation in the mucosa of the fallopian tube with the menstrual cycle

In human cervical epithelium, uterine endometrium, and mucosa of the fallopian tubes, neutral glycosphingolipids were exclusively represented by the globo-series glycosphingolipids, such as CMH, LacCer, Gb3Cer and Gb4Cer, but the molecular species of their ceramide moieties were characteristically altered in the cervical epithelium and uterine endometrium during the menstrual cycle. Individual neutral glycosphingolipids in the cervical epithelium and the uterine endometrium at the follicular phase gave two bands on TLC, whereas those at the luteal phase displayed three bands, the third being the lower migrating one. Neutral glycosphingolipids migrating to the same positions as these lower-migrating bands were constantly detected in the mucosa of the fallopian tubes, independent of the menstrual cycle. The lower-migrating bands for the cervical epithelium and the uterine endometrium at the luteal phase were due to molecules mainly constructed of phytosphingosine with alpha-hydroxy fatty acids having chain lengths of 18-24 and 4-sphingenine with alpha-hydroxy fatty acids having chain lengths of 16-22, whereas those in the mucosa of the fallopian tubes were exclusively N-alpha-hydroxypalmitoyl 4-sphingenine.

Common phenotypic expression of gangliosides GM3 and GD3 in normal human tissues and neoplastic skin lesions

The expression of gangliosides in non-malignant tissues (epidermis and pigmented nevus) and neoplastic lesions (melanoma, squamous cell carcinoma [SCC] and basal cell carcinoma [BCS]) of the human skin was analyzed immunohistochemically and biochemically to characterize the features associated with malignancy. Immunohistochemical staining with an anti-II3NeuAc-LacCer (GM3) monoclonal antibody (M2590 mAb) and an anti-II3(NeuAc)2-LacCer (GD3) mAb (R24) showed the expression of the gangliosides GM3 and GD3 to vary among the different tissues. M2590 clearly stained epidermal keratinocytes and the tumor cells of BCC and SCC, and strongly stained melanocytes and melanoma cells. In contrast, R24 did not stain epidermal keratinocytes and only faintly stained SCC cells, while it clearly stained BCC cells, and intensely stained melanocytes and melanoma cells. GM3 showed a similar level of staining among the tissue specimens, while the level of GD3 staining was quite variable among the tumor specimens. Biochemical analysis by thin-layer chromatography (TLC) with resorcinol staining and TLC immunostaining with either M2590 or R24 showed both GM3 and GD3 to be commonly expressed by both the normal and malignant skin tissues, including SCC. There was no close correlation between the intensity of immunohistochemical staining and the biochemically detected amounts of these gangliosides. This may have been partly due to the so-called cryptic expression of cell membrane gangliosides. Our results thus suggest that analysis of the tumor-associated expression of gangliosides requires several methods, since the sensitivity of the methods used may have a considerable effect on the diagnostic value of gangliosides as skin cancer markers.

Developmental changes of fucosylated glycoconjugates in rabbit dorsal root ganglia

Developmental changes of the fucosylated glycoconjugates in the dorsal root ganglia (DRG) of the rabbit were investigated histochemically using anti-fucosyl GM1 antibody and Ulex europaeus agglutinin 1 (UEA-1) lectin. Neither anti-fucosyl GM1 antibody nor UEA-1 lectin bound to the neural tubes or to the neural crest on embryonic day 14 (E14). Anti-fucosyl GM1 antibody binds diffusely to the DRG of E25. Large neurons unreactive with anti-fucosyl GM1 antibody appeared at 1 month and increased within 6 months after birth. Schwann cells immunoreactive with anti-fucosyl GM1 antibody came to be limited to the satellite cells surrounding the positive neurons. No staining with UEA-1 lectin was observed in the DRG of E25. Some small neurons became reactive with UEA-1 lectin within 1 month and remained to be so at 6 months after birth. Schwann cells including satellite cells were unreactive with this lectin. Since fucosyl GM1 was detected in the lipid fraction of DRGs from 1-month-old and 6-month-old rabbits, fucosyl GM1 itself should be the antigen molecule recognized by the anti-fucosyl GM1 antibody. Further study is necessary to elucidate the association between these developmental changes of the fucosylated glycoconjugates in DRG and their possible functional roles.