Identification of disialosyl paragloboside and O-acetyldisialosyl paragloboside in cerebellum and embryonic cerebrum

The Structural Diversity of Natural Glycosphingolipids (GSLs)

Glycosphingolipids (GSLs) are a subclass of glycolipids made of a glycan and a ceramide that, in turn, is composed of a sphingoid base moiety and a fatty acyl group. GSLs represent the vast majority of glycolipids in eukaryotes, and as an essential component of the cell membrane, they play an important role in many biological and pathological processes. Therefore, they are useful targets for the development of novel diagnostic and therapeutic methods for human diseases. Since sphingosine was first described by J. L. Thudichum in 1884, several hundred GSL species, not including their diverse lipid forms that can further amplify the number of individual GSLs by many folds, have been isolated from natural sources and structurally characterized. This review tries to provide a comprehensive survey of the major GSL species, especially those with distinct glycan structures and modification patterns, and the ceramides with unique modifications of the lipid chains, that have been discovered to date. In particular, this review is focused on GSLs from eukaryotic species. This review has listed 251 GSL glycans with different linkages, 127 glycans with unique modifications, 46 sphingoids, and 43 fatty acyl groups. It should be helpful for scientists who are interested in GSLs, from isolation and structural analyses to chemical and enzymatic syntheses, as well as their biological studies and applications.

Lipid composition of whole brain and cerebellum in Hurler syndrome (MPS IH) mice

Hurler syndrome (MPS IH) is caused by a mutation in the gene encoding alpha-L-iduronidase (IDUA) and leads to the accumulation of partially degraded glycosaminoglycans (GAGs). Ganglioside content is known to increase secondary to GAG accumulation. Most studies in organisms with MPS IH have focused on changes in gangliosides GM3 and GM2, without the study of other lipids. We evaluated the total lipid distribution in the whole brain and cerebellum of MPS IH (Idua⁻/⁻) and control (Idua(+/?)) mice at 6 months and at 12 months of age. The content of total sialic acid and levels of gangliosides GM3, GM2, and GD3 were greater in the whole brains of Idua⁻/⁻ mice then in Idua (+/?) mice at 12 months of age. No other significant lipid differences were found in either whole brain or in cerebellum at either age. The accumulation of ganglioside GD3 suggests that neurodegeneration occurs in the Idua⁻/⁻) mouse brain, but not to the extent seen in human MPS IH brain.

Neurochemical, morphological, and neurophysiological abnormalities in retinas of Sandhoff and GM1 gangliosidosis mice

Retinal abnormalities are well documented in patients with ganglioside storage diseases. The total content and distribution of retinal glycosphingolipids was studied for the first time in control mice and in Sandhoff disease (SD) and GM1 gangliosidosis mice. Light and electron microscopy of the SD and the GM1 retinas revealed storage in ganglion cells. Similar to previous findings in rat retina, GD3 was the major ganglioside in mouse retina, while GM2 and GM1 were minor species. Total ganglioside content was 44% and 40% higher in the SD and the GM1 retinas, respectively, than in the control retinas. Furthermore, GM2 and GM1 content were 11-fold and 51-fold higher in the SD and the GM1 retinas than in the control retinas, respectively. High concentrations of asialo-GM2 and asialo-GM1 were found in the SD and the GM1 retinas, respectively, but were undetectable in the control retinas. The GSL abnormalities in the SD and the GM1 retinas reflect significant reductions in beta-hexosaminidase and beta-galactosidase enzyme activities, respectively. Although electroretinograms appeared normal in the SD and the GM1 mice, visual evoked potentials were subnormal in both mutants, indicating visual impairments. Our findings present a model system for assessing retinal pathobiology and therapies for the gangliosidoses.

Molecular markers that identify human astrocytomas and oligodendrogliomas

The classification of human gliomas is currently based solely on neuropathological criteria. Prognostic and therapeutic parameters are dependent upon whether the tumors are deemed to be of astrocytic or oligodendroglial in origin. We sought to identify molecular reagents that might provide a more objective parameter to assist in the classification of these tumors. In order to identify mRNA transcripts for genes normally transcribed exclusively by oligodendrocytes. Northern blot analysis was carried out on RNA samples from 138 human gliomas. Transcripts encoding the myelin basic protein (MBP) were found in an equally high percentage of tumors that by neuropathological criteria were either astrocytic or oligodendroglial. In contrast, proteolipid protein (PLP) and cyclic nucleotide phosphodiesterase (CNP) mRNA molecules were found significantly more often in oligodendrogliomas than in astrocytomas. The strongest association with histological typing was found with the transcript for the myelin galactolipid biosynthetic enzyme UDP-galactose: ceramide galactosytransferase (CGT), which was about twice as frequently detected in tumors of oligodendroglial type. Results of glycolipid analyses were previously reported on a subset of the tumors studied herein. Statistical analyses of both molecular and biochemical data on this subset of astrocytomas, oligoastrocytomas, and oligodendrogliomas were performed to determine if a panel of markers could be used to separate astrocytic and oligodendroglial tumors. The presence of asialo GM1 (GA1) and the absence of paragloboside occurred most frequently in oligodendrogliomas. Ceramide monohexoside (CMH) levels correlated highly with the expression of mRNA for 4 myelin proteins: CGT, MBP, CNP, and PLP. The best combination of 2 markers of oligodendroglial tumors was CGT and GA1; the best combination of 3 markers was the presence of CGT, GA1, and the absence of paragloboside. We conclude that this combination of markers could be useful in distinguishing between astrocytic and oligodendroglial tumors.

CDw60: an antigen expressed in many normal tissues and in some tumours

CDw60 is a recently described T-cell antigen, which functionally delivers a costimulatory signal in T-cell activation. In addition, CDw60 has been regarded as a melanoma-associated antigen. To date, only limited information exists on the distribution of CDw60 in other normal and pathologically altered tissues in human. In the present study, the expression of CDw60 was analysed immunohistologically in a large panel of formalin-fixed and paraffin-embedded normal and pathological human tissues. The antigen was detected in several normal tissues, such as epithelia of the reproductive system, exocrine and endocrine glands, glial cells and neurons of the central and peripheral nervous systems, and lymphoid cells. These showed different subcellular distribution patterns, i.e. (1) cell surface labelling of peripheral lymphocytes and lymphocytes of the lymph node and thymus, (2) diffuse cytosolic staining in lymphocytes, subpial glial processes, and the outer plexiform layer of the retina, (3) granular cytoplasmic staining associated with the Golgi apparatus in epithelial cells of certain endocrine and exocrine glands, of the ductus epididymis and deferens, neurons of the peripheral and central nervous system, and lymphocytes and megakaryocytes of the bone marrow. In exocrine glands, e.g. of the prostate and uterine corpus, CDw60-positive Golgi fields were located in the juxtaluminal cell compartment, thus reflecting a polarized distribution. In some malignant tumours, the neoplastic cells contained CDw60-immunolabelled Golgi complexes, which were disorderly distributed throughout the cytoplasm, thus reflecting a loss of epithelial polarity. Only in mammary carcinomas was abnormal cell surface labelling detected. A putative de novo expression of CDw60 was observed in pleomorphic adenoma and mucoepidermoid carcinoma of the parotid gland, seminoma, embryonal and teratocarcinoma of the testis, small cell carcinoma of the lung, and malignant melanoma. These results define the CDw60 determinant as a broadly distributed antigen within a large panel of normal human tissues. The antigen is also detectable in some previously undescribed benign and malignant tumours, which may give importance to CDw60 as a possible diagnostic marker.

An immunocytochemical technique with monoclonal antibodies to glycosphingolipids in rat primary cerebellar cultures: influence of detergent permeabilization

Glycosphingolipids (GSLs) are highly expressed in the vertebrate central nervous system. GSLs have been implicated in a variety of phenomena involving cell-cell recognition, neurite outgrowth, synaptogenesis, transmembrane signalling and cell growth and differentiation. We recently determined the distribution of GSLs in rat brain tissues and in primary rat cerebellar cultures as well as using a number of MAbs to GSLs, which were generated and characterized in our laboratory. These results suggested that (i) the expression of GSLs was highly localized to a specific cell type and layer in the rat brain tissues and (ii) some GSLs may be useful markers for identifying cells in the primary cultures. In the present paper, we describe in detail an immunofluorescence technique for the detection of GSL expression in the primary cultures. We demonstrate that the localization of GSLs can be greatly influenced by detergent treatments.

Developmentally regulated O-acetylated sialoglycans in the central nervous system revealed by a new monoclonal antibody 493D4 recognizing a wide range of O-acetylated glycoconjugates

We have previously detected an alkali-labile and developmentally regulated antigen in rat embryonic cerebral cortex, which may be 9-O-acetylsialylated GT3 ganglioside (Hirabayashi Y, Hirota M, Suzuki Y, Matsumoto M, Obata K, Ando S (1989) Neurosci Lett 106:193-98). In this study we established a mouse monoclonal antibody, 493D4, that recognizes 9-O-acetyl GT3 ganglioside, but not non-O-acetyl gangliosides. This antibody also reacted with 9-O-acetyl GD3 to a much lesser extent. By using this antibody, we found that O-acetyl GT3 as well as O-acetyl GD3 were expressed strongly in fetal murine cerebral cortex and decreased to an undetectable level after birth. With the assistance of TLC-immunostaining using 493D4 together with Q-Sepharose column chromatography, O-acetyl gangliosides of bovine brain were purified and the structural analysis showed the presence of O-acetyl GD3, O-acetyl LD1, O-acetyl GD2 and O-acetyl GD1b in the adult brain as extremely minor components. Interestingly, the antibody 493D4 could detect O-acetyl sialoglycoproteins in rat brain tissues. One of the major immunoreactive proteins was shown to be synaptophysin, an integral membrane protein specifically present in synaptic vesicles. This monoclonal antibody was therefore useful for sensitive detection of both O-acetylated gangliosides and glycoproteins with O-acetylated sialic acids.

Expression cloning and characterization of a cDNA encoding a novel membrane protein required for the formation of O-acetylated ganglioside: a putative acetyl-CoA transporter

By expression cloning using COS-1 cells stably transfected with GD3-synthase (COS-1/GD3+) as a recipient cell line, we have isolated a cDNA, termed AT-1, encoding a novel protein required for the formation of O-acetylated (Ac) gangliosides. The cDNA encodes a protein with multitransmembrane spanning domains with a leucine zipper motif. It consists of 549 amino acids and has a molecular mass of 60.9 kDa. Although both O-Ac-GD3 and O-Ac-GT3 were barely detectable in recipient cells or cells transfected with the vector alone, their amount increased significantly in transfectants containing AT-1. When semi-intact cells prepared by treatment with streptolysin O were incubated with [Ac-14C]-Ac-CoA, increased incorporation of radioactivity was found in those cells transfected with AT-1 when compared with the mock transfectants. Northern blot analysis showed two major transcripts of 3.3 and 4.3 kb in all tissues examined. Immunohistochemical study with an antibody specific to the AT-1 protein suggested that it is most probably expressed in the endoplasmic reticulum membrane. Based on these results, the protein encoded by AT-1 is suggested to be an Ac-CoA transporter that is involved in the process of O-acetylation.

N-Acetylglucosaminyl transferase regulates the expression of the sulfoglucuronyl glycolipids in specific cell types in cerebellum during development

In the adult cerebellum, sulfoglucuronyl glycolipids (SGGLs) are specifically localized in Purkinje cells and their dendrites in the molecular layer. Other major cell types such as granule neurons and glial cells lack SGGLs. To explain the cell specific localization and the known biphasic expression of SGGLs, enzymic activities of four glycosyltransferases involved in the biosynthesis of SGGLs were studied in murine cerebellar mutants, in distinct cellular layers of rat cerebellum, and in isolated granule neurons during development. The enzymes studied were lactosylceramide: N-acetylglucosaminyl transferase (GlcNAc-Tr), lactotriaosylceramide:galactosyltransferase, neolactotetraosylceramide:glucuronyltransferase, and glucuronylglycolipid:sulfotransferase. In the cerebellum of Purkinje cell-deficient mutants, such as (pcd/pcd) and lurcher (Lc/+) where Purkinje cells are lost, GlcNAc-Tr was absent, but the other three glycosyltransferase were not severely affected. This indicated that the latter three enzymes were localized in other cell types, such as in mature granule neurons and glial cells, in addition to that in Purkinje cells, and the lack of SGGLs in these mutants was due to absence of GlcNAc-Tr. Analyses of the enzymes in the specific micro-dissected cellular layers also showed that Purkinje cell layer and molecular layer (where Purkinje cell dendrites are localized) contained all four enzymes. However, granule neurons and glial cells in the white matter lacked GlcNAc-Tr, but expressed the other three enzymes. It was concluded that the absence of SGGLs in adult granule neurons and glial cells was due to specific deficiency of the GlcNAc-Tr. Although adult granule neurons lacked GlcNAc-Tr and therefore SGGLs, isolated granule neurons from the neonatal cerebellum contained all four enzymes necessary for the synthesis of SGGLs. With development, the activity of GlcNAc-Tr in the isolated granule neurons declined but the other enzymes were not as affected, indicating that immature granule neurons were capable of synthesizing SGGLs and with maturation the synthesis was down-regulated. This also explains the biphasic expression of SGGLs in the developing cerebellum.

Immunocytochemical analysis of gangliosides in rat primary cerebellar cultures using specific monoclonal antibodies

We studied the expression of ganglioside antigens in primary cultures of rat cerebellum using an immunocytochemical technique with mouse monoclonal antibodies (MAbs) specific for various gangliosides. Twelve MAbs that specifically recognize each ganglioside were used. Our study revealed that there is a cell type-specific expression of ganglioside antigens in the primary cultures. A number of b-series gangliosides were detected in the granule cells, whereas a-series gangliosides were not intensely expressed. GD1b was detected in the granule cells. GD2 appeared to be present in a subset of the granule cells or a type of small neurons. GD3 was associated not only with the granule cells, but also with both astrocytes and oligodendrocytes. An O-Ac-disialoganglioside, which was suggested to be O-Ac-LD1, was restrictedly detected in Purkinje cells. The other gangliosides were not detected clearly in these cells. These results suggest that several gangliosides may be useful markers for identifying cells in primary cultures of the rat cerebellum; particularly b-series gangliosides such as GD2 and GD1b for the granule cells and O-Ac-LD1 for Purkinje cells.

Binding specificity of influenza C-virus to variably O-acetylated glycoconjugates and its use for histochemical detection of N-acetyl-9-O-acetylneuraminic acid in mammalian tissues

The specificity of influenza C-virus binding to sialoglycoconjugates was tested with various naturally O-acetylated gangliosides or synthetically O-acetylated sialic acid thioketosides, which revealed binding to 9-O-acetylated N-acetylneuraminic acid. Binding was also observed with a sample of Neu5,7Ac2-GD3, however at a lower degree. Sialic acids with two or three O-acetyl groups in the side chain of synthetic sialic acid derivatives are not recognized by the virus. In these experiments, bound viruses were detected with esterase substrates. Influenza C-virus was also used for the histological identification of mono-O-acetylated sialic acids in combination with an immunological visualization of the virus bound to thin-sections. The occurrence of these sialic acids was demonstrated in bovine submandibular gland, rat liver, human normal adult and fetal colon and diseased colon, as well as in human sweat gland. Submandibular gland and colon also contain significant amounts of glycoconjugates with two or three acetyl esters in the sialic acid side chain, demonstrating the value of the virus in discriminating between mono- and higher O-acetylation at the same site. The patterns of staining showed differences between healthy persons and patients with colon carcinoma, ulcerative colitis or Crohn's disease. Remarkably, some human colon samples did not show O-acetyl sialic acid-specific staining. The histochemical observations were controlled by chemical analysis of tissue sialic acids.

Acceptor substrate specificity of a cloned GD3 synthase that catalyzes the biosynthesis of both GD3 and GD1c/GT1a/GQ1b

To address the role of alpha2,8-sialyltransferase (GD3 synthase) in the biosynthesis of gangliosides, we examined the substrate specificity of the enzyme. In the ganglioside synthesis pathway, it has been generally accepted that sialyltransferase II (SAT II) catalyzes the production of GD3 from GM3, and sialyltransferase V (SAT V) catalyzes the production of GD1c/GT1a/GQ1b from GM1h/GD1a/GT1b. However, acceptor specificity of the clones GD3 synthase that was isolated from human melanoma cells [Nara, K., Watanabe, Y., Maruyama, K., Kasahara, K., Nagai. Y. & Sanai, Y. (1994) Proc. Natl Acad. Sci. USA 91, 7952-7956] has revealed that this enzyme utilized the gangliosides containing the terminal Sia(alpha2-3)Gas structure of the carbohydrate moiety, which includes GM3, GM1b, GD1a and GT1B as exogenous substrates. Kinetic data also showed that the enzyme was able to utilize both GM3 and GM1b/GD1a/GT1b as acceptor substrates. These data indicate that the enzyme catalyzes the formation of not only GD3 but also GD1c, GT1a, and GQ1B in vitro. Furthermore, by transfection of the cloned human alpha2,8-sialyltransferase cDNA, transient and stable expression of GT1a and GQ1b wa also observed in COS-7 cells and Swiss 3T3 cells that originally lacked SAT II and SAT V activities. These observations indicate that the enzyme has both SAT II and SAT V activities in vivo.

Expression of neolactoglycolipids: sialosyl-, disialosyl-, O-acetyldisialosyl- and fucosyl- derivatives of neolactotetraosyl ceramide and neolactohexaosyl ceramide in the developing cerebral cortex and cerebellum

The following neolacto glycolipids were identified and their developmental expression was studied in the rat cerebral cortex and cerebellum: Fuc alpha 1-3IIInLcOse4Cer,Fuc alpha 1-3VnLcOse6Cer and (Fuc)2 alpha 1-3III,3VnLcOse6Cer, as well as acidic glycolipids, NeuAc alpha 2-3IVnLcOse4Cer [nLM1], (NeuAc)2 alpha 2-3IVnLcOse4Cer [nLD1], O-acetyl (NeuAc)2 alpha 2-3IVnLcOse4Cer [OAc-nLD1] and their higher neolactosaminyl homologues NeuAc alpha 2-3VlnLcOse6Cer [nHM1] and (NeuAc)2 alpha 2-3VlnLcOse6Cer [nHD1]. These glycolipids were expressed in the cerebral cortex only during embryonic stages and disappeared postnatally. This loss was ascribed to the down regulation of the synthesis of the key precursor LcOse3Cer which is synthesized by the enzyme lactosylceramide: N-acetylglucosaminyl transferase. On the other hand in the cerebellum, these glycolipids increased with postnatal development due to increasing availability of LcOse3Cer. In the cerebellum, only nLM1 and fucosyl-neolactoglycolipids declined after postnatal day 10-15, perhaps due to regulation by other glycosyltransferases. Also, in the cerebellum, nLD1 and nHD1 were shown to be specifically associated with Purkinje cells and their dendrites in the molecular layer and with their axon terminals in the deep cerebellar nuclei, similar to other neolactoglycolipids shown previously.

Developmental changes of ganglioside expressions in postnatal rat cerebellar cortex

We previously described the differential distribution of gangliosides in adult rat brain as detected by specific antibodies. We report here the distribution of gangliosides during the development of postnatal rat cerebellum by an immunofluorescence technique with mouse monoclonal antibodies (mAbs). Eleven mAbs that specifically recognize each ganglioside were used. Our study revealed that the expression of each ganglioside changed dramatically during the development. GD3 and O-Ac-GD3 were expressed intensely in the external granular layer at 1, 5, and 10 days, whereas GD2 was firstly detected in the internal granular layer at 5 days and GD1b WAS diffusely detected throughout all layers of the cerebellar cortex at early postnatal days. GD2 and GD1b were more intensely expressed in the granular layer at 20, 30, and 80 days, suggesting that premature granule cells expressed GD3 and its derivative, O-Ac-GD3, whereas mature granule cells express GD2 and GD1B intensely. On the other hand, GM1 was exclusively detected in the external granular layer and the molecular layer at 1 and 5 days. The staining sites spread gradually from these outer layers into the internal granular layer and the white matter after 10 days. The positive cells in the external granular layer and the molecular layer appeared to be Bergmann glial cells and their radially ascending cytoplasmic processes. The intensity of the staining in these specialized astroglial cells decreased gradually during postnatal days. In contrast, the expression of GQ1b was very faint at birth, but gradually increased during the development and was detected intensely in the internal granular layer, particularly in the cerebellar glomeruli in adulthood, suggesting that GQ1b expression may be associated with synapse-related structures. The developmental changes of the expression of other gangliosides were also recognized in the postnatal rat cerebellum. These results suggest that specific gangliosides may play an important role in regulating the early events responsible for the orderly formation of the cerebellar cortex.

Purkinje cell compartments in the reeler mutant mouse as revealed by Zebrin II and 90-acetylated glycolipid antigen expression

The cerebellum is organized into a series of parasagittally aligned bands that may be revealed histologically in the adult mouse by largely complementary immunostaining of Purkinje cells sets with the monoclonal antibodies Zebrin II (ZII; antigen:aldolase C) and P-path (PP; antigen:90-acetyl glycolipids). We compared the normal staining pattern using these markers and an antibody to calbindin with that found in the reeler mutants (rl/rl), in which most Purkinje cell migration is halted beneath the cerebellar white matter. The results revealed that Purkinje cells in reeler mutants, despite their ectopic location in large subcortical masses, show a clear tendency to distribute into alternating zones that either stain for Zebrin II or for P-path, with variable transition zones of mixed labeling. However, the estimated number of zones was fewer than in the normal adult cortex: roughly 7-9 zones are revealed per side in the mutant compared with 14 major divisions in wild type mice. These results raise the possibility that neurons destined to express these markers are segregated during their migration and that the final phase of migration into the cortex might involve further splitting or interdigitation between cell sets expressing the two antigens.

Altered 9-O acetylation of disialogangliosides in cerebellar Purkinje cells of the nervous mutant mouse

Some gangliosides in the nervous system are developmentally down-regulated, but many other gangliosides continue to be expressed in the adult nervous system. We have previously demonstrated that the 9-O-acetylated gangliosides recognized by a monoclonal antibody, P-path, confer unique compartmentation among Purkinje cell groups in the normal adult cerebellum. We have continued to explore the role of this group of gangliosides in cerebellar organization by investigating the biochemical and cellular expression of this unique epitope in the cerebellum of the mutant mouse, nervous, where postnatally, most Purkinje cells degenerate. Overall ganglioside composition of nervous cerebellum is similar to wild type cerebellum. However, quantitative analysis of gangliosides by TLC-immunostaining shows that the relative concentration of 9-O-acetylated gangliosides varies considerably. In nervous cerebellum, there is more than a three-fold increase in the concentration of 9-O-acetyl disialolactosyl ceramide (GD3), and 9-O-acetyl disialolactoneotetraosyl ceramide (LD1) is decreased to 25% of wild type. In addition, GD3 ganglioside, the immediate precursor of 9-O-acetyl GD3, is detected at 1/3 of the level of wild type cerebellum, and LD1 ganglioside, the precursor of 9-O-acetyl LD1, is virtually absent from nervous cerebellum. Thus, in nervous cerebellum the ratio of 9-O-acetyl GD3 to its disialoganglioside precursor is dramatically increased compared to wild type cerebellum. In accord with the altered expression of 9-O-acetyl gangliosides, immunoelectron microscopy demonstrates a change in the subcellular distribution in mutant Purkinje cells. Instead of being associated with the somatic and dendritic membranes, P-path immunoreactivity is located internally, in the cytoplasm of Purkinje cell bodies and their dendrites. In addition to the changes in the cerebellum, the other regions of the brain decreased in size by about 15% in the nervous mutant. In the ganglioside composition of these regions of nervous brain, 9-O-acetyl GD3 nearly doubled, but 9-O-acetyl LD1 and other gangliosides did not differ. Our findings of significant changes in 9-O-acetylated gangliosides, accompanied by the overall decrease in brain size, suggest that carbohydrate or glycolipid metabolism is abnormal in the nervous mutant mouse brain.

Patterns of reactivity with anti-glycolipid antibodies in human primary brain tumors

Antibodies against carbohydrates of three glycolipids were used to determine patterns of immunohistochemical reactivity of histologically identifiable cell subpopulations in 101 human primary brain tumors. For all tumor types fibrillary cells, polar cells, and gemistocytes (commonly seen in astrocytomas and ependymomas) stained more frequently for galactosylcerebroside with mAbO1 than small tumor cells and macrophages. Frequency of staining for sulfatide with mAbO4 was fibrillary > polar > small cells = macrophages. Gemistocytes stained more frequently with mAbO4 than polar cells in all tumors except low grade astrocytomas. These data indicate that tumors classified on histological grounds as astrocytic are often stained with antibodies that recognize oligodendrocytes and their progenitors. Thus, anti-glycolipid antibodies used in the study of developmental lineage may offer useful tools for classification of human brain tumors. Staining of fibrillary cells, polar cells, and gemistocytes for paragloboside directly with mAb F1H11 was much less common than with mAbO1, but this increased by pretreatment of the tissues with neuraminidase (F1H11 + N). Of particular note was the finding that small tumor cells frequently stained with F1H11 + N. Evidence that these were not macrophages was obtained using double immunostaining with F1H11 + N and anti-macrophage antibodies. In astrocytomas the frequency of small tumor cells immunostained with F1H11 + N was high grade > anaplastic > low grade, demonstrating a correlation of this tumor cell population with more aggressive astrocytomas. Thus, immunostaining with F1H11 + N may be of value in identifying small, anaplastic tumor cells, especially in small biopsies or tissue taken adjacent to the main tumor mass.

Characteristics of gangliosides including O-acetylated species in growth cone membranes at several developmental stages in rat forebrain

Growth cones, the motile tips of extending neuronal processes, are involved in accurate synaptogenesis. To study the developmental changes in ganglioside composition including O-acetylated gangliosides in growth cones, we analyzed the gangliosides in growth cone membranes (GCM) prepared from rat forebrains at different developmental stages. At several stages, GCM contained significantly larger amounts of gangliosides than the other membrane subfractions. The ganglioside content of GCM increased in amount with development. Moreover, in GCM, the relative amount of GD3 gradually decreased, and that of GD1a dramatically increased. There were significant differences in the composition of ganglioside species between GCM and the perinuclear plasma membrane subfraction (NM); most importantly, GCM had a higher ratio of GD1a to GM3 plus GD3 than NM. There were three different O-acetylated gangliosides in GCM: O-acetyl-GD3, O-acetyl-GT1b, and O-acetyl-GQ1b. The molar ratio of O-acetyl-GD3 decreased in GCM at later stages (5% of the total gangliosides at embryonic day 17, to 1% at postnatal day 5). However, those of the other two O-acetylated gangliosides were almost constant (1-2% of the total). Our results show that there are significant differences in ganglioside content and composition between the membrane subfraction of growth cones and the perinuclear portion. This suggests that several species of gangliosides, including O-acetyl-GD3, play a role in growth cone function.

Effects of nervous mutation on Purkinje cell compartments defined by Zebrin II and 9-O-acetylated gangliosides expression

The cerebellum is organized into a series of parasagittally aligned bands which are well delineated in the adult mouse by the largely complementary immunostaining of Purkinje cell groups with the monoclonal antibodies Zebrin II (ZII; antigen: aldolase C) and P-path (antigen: 9-O-acetyl gangliosides). We examined the effect of nervous mutation on compartmental organization using these markers and an antibody to calbindin. In nervous mutant, up to 90% of Purkinje cells die in late postnatal development. The size of the cerebellum is about half that of normal, and caudal lobules appear to decrease in size more than anterior ones. Surviving Purkinje cells corresponded to P-path positive ones that were concentrated in two bilateral bands in the vermis and in medial portions of the hemispheres. Only small numbers of ZII positive cells remained, confirming the report by Wassef et al. with Zebrin I antibody. They were primarily located in caudal lobules IX, X and a portion of lobule IV, paraflocculus and flocculus, and their immunoreactivity was weak compared to that of normal. ZII positive cells are dominant in these caudal lobules, while P-path positive cells dominate in rostral lobules in normal mice, and the similar tendency remains in mutant. Thus, the nervous gene action respects not only sagittal compartments delineated by two antibodies, but also rostro-caudal gradient. The cause of the dominant survival of P-path positive cells awaits future study.

Characterization and developmental expression of lactotriosylceramide:galactosyltransferase for the synthesis of neolactotetraosylceramide in the nervous system

Neolactoglycolipids are derived from neolactotetraosylceramide (nLcOse4Cer). They are found during the embryonic and neonatal developmental periods in the rat cerebral cortex and disappear shortly after birth. These glycolipids are, however, abundant in the adult cerebellum. Lactotriosylceramide (LcOse3Cer):galactosyltransferase (GT), which catalyzes the terminal step in the biosynthesis of nLcOse4Cer, was characterized in mammalian brain. The enzyme was highly specific for LcOse3Cer, with a terminal GlcNAc beta 1-3Gal-residue, and it did not catalyze the transfer of galactose to other glycolipids studied with alternate carbohydrate residues. The microsomal membrane enzyme required Mn2+ and a detergent for in vitro activity. The optimal pH was 7.4, and the Km value for LcOse3Cer was 34 microM (Vmax = approximately 2 nmol/mg/h). The LcOse3Cer:GT was shown to be different from the GM2:GT and the soluble enzyme lactose synthase A. The specific activity of LcOse3Cer:GT was enriched fivefold higher in the white matter than in the gray matter of young adult rat brain, whereas GM2:GT was enriched only about 1.5-fold higher in the white matter. The developmental expression of LcOse3Cer:GT in the cerebral cortex and cerebellum was not correlative with the levels of nLcOse4Cer in these neural areas. Despite the complete absence of nLcOse4Cer in the cerebral cortex of animals older than 5 days, significant activity of the LcOse3Cer:GT was found even in the adult cortex. In cerebellum, the levels of nLcOse4Cer increased with development, but the specific activity of the enzyme was reduced by 50% soon after birth and then remained practically the same with development.(ABSTRACT TRUNCATED AT 250 WORDS)

Rostrocaudal expression of antibody HNK-1-reactive glycolipids in mouse cerebellum: relationship to developmental compartments and leaner mutation

Sulfoglucuronylglycolipids (SGGLs) and glycoproteins, reacting with monoclonal antibody HNK-1, are developmentally and spatially regulated in the mammalian cortex and cerebellum. It has been proposed that the HNK-1 carbohydrate epitope is involved in intercellular adhesion and cell-cell interactions. Biochemical analysis and immunocytochemical localization of SGGLs and other neolacto series glycolipids were studied in the leaner mutant mouse cerebellum, where a slow and progressive rostral to caudal degeneration occurs with a gradual loss of both granule cells and Purkinje cells. Biochemical analyses showed that SGGLs and other neolacto series of glycolipids were significantly decreased in the adult leaner cerebellum; however, HNK-1-reactive glycoproteins were not affected. By an immunocytochemical method which selectively localizes the lipid antigens, it is shown that SGGLs are primarily associated with Purkinje cell bodies and their dendrites in the molecular layer and in cerebellar nuclei where Purkinje cell axons terminate. At postnatal day 30 (P30), SGGL immunoreactivity (SGGL-ir) in the leaner cerebellum was reduced moderately compared to normal littermates, which correlated with the minimal degree of Purkinje cell degeneration at this age in leaner and with the biochemical data. At P67 and P90, the SGGL-ir was significantly more reduced in the leaner as Purkinje cell degeneration proceeded. There was a direct correlation between loss of Purkinje cells and SGGL-ir in the cerebellar molecular layer. In both normal and young leaner cerebella, the SGGL-ir in different lobules was not uniform; there were distinct rostrocaudal and mediolateral differences. SGGL-ir was markedly more intense in rostral than in caudal lobules in the vermis, the dividing line being the region immediately caudal to the primary fissure and rostral to the declival sulcus. In the lateral cerebellum, the SGGL-ir was less intense than in the vermis and the rostrocaudal difference was not as pronounced. There was also nonuniformity in the intensity of staining in different folia. The rostrocaudal as well as mediolateral differences in the intensity of SGGL-ir were confirmed independently by biochemical analysis. The differential phenotypic expression of SGGLs and the selective susceptibility to Purkinje cell death in leaner mutant are discussed in relation to the known embryologic and ontogenetic compartmentation of cerebellum.

CDw 60 antibodies bind to acetylated forms of ganglioside GD3

Four monoclonal antibodies, M-T21, M-T32, M-T41 and UM4D4, which belong to the new CDw 60 cluster of antibodies specific for a subpopulation of human T-lymphocytes, were found to bind mainly to acetylated forms of ganglioside GD3. After O-deacetylation of the antigen, binding was reduced ("M-T"-antibodies) or abolished (UM4D4).

Compartmentation in mammalian cerebellum: Zebrin II and P-path antibodies define three classes of sagittally organized bands of Purkinje cells

The respective roles of genetic and epigenetic factors in generation of pattern formation in the vertebrate nervous system are still poorly elucidated. The mammalian cerebellum is subdivided in parasagittal modules defined by anatomical, physiological, and biochemical criteria. Immunostaining of adult mouse cerebellum with two monoclonal antibodies, P-path, which recognizes 9-O-acetylated glycolipids, and Zebrin II, which recognizes a 36-kDa protein, reveals three classes of sagittally organized bands of Purkinje cells: two complementary groups distinctly immunoreactive to one antibody but not the other and a third group that contains double-labeled cells. No Purkinje cells could be detected that were unreactive to either antibody. The specific and reproducible topography of these three classes of Purkinje cells may be related to the compartmentation of the cerebellum into developmental genetic modules.

Temporal Expression of HNK-1-Reactive Sulfoglucuronyl Glycolipid in Cultured Quail Trunk Neural Crest Cells: Comparison with Other Developmentally Regulated Glycolipids

Monoclonal antibody HNK-1 is an important marker for embryonic neural crest cells and some of their differentiated derivatives. We have identified 3-sulfoglucuronylneolactotetraosylceramide (SGGL-1) as one of the HNK-1 antigens present in cultures of trunk neural crest cells. This lipid was present at 2 days in vitro and increased in amount with time in culture. Other major HNK-1-reactive antigens present in the culture were glycoproteins of apparent molecular masses of 120, 180, and 200 kDa. The 180- and 200-kDa bands were present at 2, 7, and 17 days in vitro, whereas the 120-kDa band was present only at 17 days in vitro. Gangliosides GD3, LD1, and LM1 were also found in the cultures and exhibited distinct temporal patterns of expression. Ganglioside GD3 was present at all stages examined and its expression peaked at 7 days in vitro. In contrast, LD1 was present only at 2 days in vitro and was not detectable at later times. Ganglioside LM1 increased in amount with time in culture in a pattern similar to that seen for SGGL-1. Taken together, these results indicate that several HNK-1-reactive molecules are expressed in neural crest cultures in a temporally regulated manner along with several glycolipids that do not bear this epitope.

Developmental abnormalities in transgenic mice expressing a sialic acid-specific 9-O-acetylesterase

9-O-acetylation of sialic acids is tissue specific and developmentally regulated. We have selectively destroyed these O-acetyl groups during murine embryogenesis by expressing the 9-O-acetyl-sialic acid-specific esterase of influenza C. DNA constructs driven by the metallothionein promoter arrested development at the 2-cell stage and gave a markedly decreased yield of live mice. A similar construct driven by the phenylethanolamine-N-methyltransferase promoter did not cause this block, but gave transgenic mice with selective expression of esterase in the retina and the adrenal gland. These organs showed variable abnormalities in organization, while all other tissues examined appeared normal. The ganglioside 9-O-acetyl-GD3 was selectively destroyed in target tissues. Thus, 9-O-acetylated sialic acids may play an role in murine development at the 2-cell stage and in certain differentiated tissues.

Loss of sulfoglucuronyl and other neolactoglycolipids in Purkinje cell abnormality murine mutants

A significant reduction in the content of two members of the sulfoglucuronyl-neolacto series of glycolipids (SGGLs), 3-sulfoglucuronyl-lacto-N-neotetraosylceramide (SGGL-1) and 3-sulfoglucuronyl lacto-N-norhexaosylceramide (SGGL-2), in the cerebellum of the Purkinje cell abnormality mutants, Purkinje cell degeneration (pcd/pcd), lurcher (Lc/+), and staggerer (sg/sg), was also confirmed in the mildly affected nervous (nr/nr) mutant. The expression of SGGLs was studied during development of the pcd/pcd mutant cerebellum, and it was shown that the rate of decline in the level of SGGLs practically coincided with the loss of Purkinje cell perikarya. This indicated that SGGLs are primarily localized in Purkinje cells and that initially, at least, there is no genetic defect in the biosynthesis of SGGLs in the mutant. The precursors of SGGLs, viz., lacto-N-neotetraosylceramide (paragloboside) and lacto-N-norhexaosylceramide, as well as other glycolipids derived from these precursors, such as X-determinant fucoglycolipids and disialosyllacto-N-neotetraosylceramide, were also present in normal cerebellum. Levels of paragloboside and its other derivatives, similar to SGGLs, were also significantly reduced in the Purkinje cell abnormality mutants pcd/pcd, sg/sg, Lc/+, and nr/nr but were normal in other cerebellar mutants, such as quaking (qk/qk), weaver (wv/wv), and reeler (rl/rl), where Purkinje cells are not involved. Thus, the entire paragloboside family of glycolipids is primarily associated with Purkinje cells in the cerebellum. Although levels of monoclonal antibody HNK-1-reactive glycolipids were reduced in the Purkinje cell abnormality mutants, HNK-1-reactive glycoproteins were not affected in these mutants.