Discovery of an α2,9-PolyNeu5Ac Glycoprotein in C-1300 Murine Neuroblastoma (Clone NB41A3)

Abstract

␣2,8-PolyNeu5Ac is expressed on neural cell adhesion molecules during embryogenesis and also re-expressed on certain tumors. PolyNeu5Ac is therefore an oncodevelopmental antigen, has important regulatory effects on the adhesive and migratory behavior of neural cells, and is thus crucial to synaptic plasticity. Until now, ␣2,9-polyNeu5Ac, a linkage isomer of ␣2,8-polyNeu5Ac, has long been thought to occur only in capsules of neuroinvasive Neisseria meningitidis group C bacteria. Here we report the unexpected discovery of ␣2,9-polyNeu5Ac in a new cell adhesion-related glycoprotein on the membrane of C-1300 murine neuroblastoma cells (clone NB41A3). We also report the expression of ␣2,9-polyNeu5Ac was affected by cell growth and retinoic acid-induced differentiation. Occurrence of the linkage isomer of ␣2,8-polyNeu5Ac has been left unrecognized by conventional methods using biological diagnostic probes for ␣2,8-polyNeu5Ac. Thus, our discovery may change contemporary views of biology and pathology of polysialic acid and open new avenues for the development of anti-neural tumor drugs.Polysialic acid (PSA) 1 is a unique cell surface homopolymer that is expressed by clinically important serogroups B and C Neisseria meningitidis in ␣2,8-and ␣2,9-linked isomers respectively (1) (Fig. 1). These molecules encapsulate the organisms, which are responsible for a dominant portion of all cases of meningococcal meningitis, and are critical to their pathogenesis. One of these linkage isomers, ␣2,8-polyNeu5Ac, which also forms the capsule of neuroinvasive Escherichia coli K1, is poorly immunogenic (2), probably due to the fact that it is a self-antigen occurring as an oncodevelopmentally regulated mammalian antigen in the neural cell adhesion molecule (NCAM) and certain tumors. In contrast ␣2,9-polyNeu5Ac is immunogenic enough to be used as a vaccine against meningitis caused by group C meningococci and is expressed by these organisms in both O-acetylated and O-deacetylated forms (2). Since the 1980s, the molecular biology, structural biology, and physiological and pathophysiological functions of ␣2,8-polyNeu5Ac on NCAM have already been the subject of major reviews (3-7). Usually detection and identification of ␣2,8-PSA in NCAM studies are made using monoclonal antibodies (mAbs) specific to ␣2,8-polyNeu5Ac. Although such immunological reagents are useful for studies of developmentally regulated dynamic expression of ␣2,8-polyNeu5Ac, they cannot be used to define DP or to detect either changes in the distribution of glycoforms differing in DP or the presence of PSA differing in sequences or inter-residue linkages. Prior to the identification of ␣2,8-polyNeu5Ac-NCAM, we discovered ␣2,8-polyNeu5Gc by chemical and biochemical methods, which was the first example of animal PSA (8, 9). Later we also unveiled divergent forms of PSA, such as an ␣2,8-poly(Neu5Ac, Neu5Gc) co-polymer, ␣2,8-polyKDN, and ␣2,5-Oglycolyl-linked oligo/polyNeu5Gc (10, 11). These PSA-glycoproteins (gp) were shown to play biological functions in fertilization and e...

The molecular basis for the distinct host and tissue tropisms of coccidian parasites

“…3C) which includes the HxT motif and adjacent positively-charged residues which have been suggested to mediate ␣2,9-disialyl binding [25]. It can be inferred that ␣2,9-disialyl binding by TgMIC13 may be a crucial mediator of human infection by T. gondii; however the prevalence of this moiety within host tissues is not well understood at present, although it has been discovered on human embryonal carcinoma [64] and murine neuroblastoma cell surfaces [65].…”

Members of a Novel Protein Family Containing Microneme Adhesive Repeat Domains Act as Sialic Acid-binding Lectins during Host Cell Invasion by Apicomplexan Parasites

“…It has been reported as a component on a murine neuroblastoma cell line (38) and a human embryonal carcinoma cell line (39). The distribution of ␣2-9-linked disialyllactose in HFFs, C6 rat glioma, and CHO cells has not been described; this and its susceptibility to neuraminidases will be the subject of future investigation.…”

KDN (Deaminated neuraminic acid): Dreamful past and exciting future of the newest member of the sialic acid family

“…N-Glycolylneuraminic acid (Neu5Gc) that is not expressed in normal human cells has been reported to be expressed in gangliosides of colon cancer tissues [91], and in human tumor mucin [92]. Unusual sialyl structures have also been reported in some tumor cell lines, for examples α2,9-linked dimer of Neu5Ac in human ovarian teratocarcinoma cell PA-1, α2,8-linked polyNeu5Ac in MCF7 human breast cancer and RBL rat basophilic leukemia cells, and α2,9-linked polyNeu5Ac in murine neuroblastoma (clone NB41A3), but the functional significance of these glycotopes remains unsolved [93][94][95]. As an unusual type of sialic acid, KDN is a candidate sugar residue that occurs not only during normal development but whose aberrant expression may also underlie some metabolic disorders and malignant transformation.…”