• Development and Reproduction
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• v.2 no.2
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• pp.149-155
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• 1998

The polysialic acid (polySia) glycotope covalently modifies cell surface glycoconjugates on cells as evolutionarily diverse as microbes and human. The recent chemical identification of polysialylated glycoproteins in the jelly coat and on the cell surface of the sea urchin egg raises important questions about their biosynthesis and possible function. Using CMP-[$^{14}$ C]Neu5Ac as substrate and cell free preparations from eggs and embryos of the sea urchin Stronglylcentrotus nudus, we have identified a membrane associated CMP-Neu5Ac:poly-$\alpha$2, 8 sialosyl sialyltransferase (polyST) that transfers Neu5Ac to an endogenous acceptor. Optimal conditions for the polyST activity were found to be 2$0^{\circ}C$ in 20 mM MOPS buffer (pH 7.0). The polyST activity was increased 2.7 times by the addition of 10 mM $Mg^2$$^{+}$. The membrane-associated polyST also catalyzed the polysialylation of mammalian ganglioside GD3. Given that no structurally similar natural polysialylated gangliosides have been described, nor were observed in the present study, we conclude that a single polyST activity catalyzes sialylation of the endogenous acceptor and the gangliosides. Using an excess of GD3 as an exogenous acceptor, it was established that the expression of the polyST in S. nudus embryos increased rapidly at the mesenchyme blastula stage and reached at maximum at the gastrula stage. The finding that this polyST in the sea urchin embryo is developmentally regulated raises the possibility that it may play a role in the changing cell and tissue interactions that occur during gastrulation and the early stages of spicule formation.n.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.23
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• pp.10217-10223
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• 2015

Hyperactivated ${\alpha}2$-6-sialylation on N-glycans due to overexpression of the Golgi enzyme ${\beta}$-galactoside: ${\alpha}2$-6-sialyltransferase (ST6Gal-I) often correlates with cancer progression, metastasis, and poor prognosis. This study was aimed to determine the association between ST6Gal-I expression and the risk of recurrence and survival of patients with localized clear-cell renal cell carcinoma (ccRCC) following surgery. We retrospectively enrolled 391 patients (265 in training cohort and 126 in validation cohort) with localized ccRCC underwent nephrectomy at a single center. Tissue microarrays were constructed for immunostaining of ST6Gal-I. Prognostic value and clinical outcomes were evaluated. High ST6Gal-I expression was associated with Fuhrman grade (p<0.001 and p=0.016, respectively) and the University of California Los-Angeles Integrated Staging System (UISS) score (p=0.004 and p=0.017, respectively) in both cohorts. Patients with high ST6Gal-I expression had significantly worse overall survival (OS) (p<0.001 and p<0.001, respectively) and recurrence free survival (RFS) (p<0.001 and p=0.002, respectively) than those with low expression in both cohorts. On multivariate analysis, ST6Gal-I expression remained associated with OS and RFS even after adjusting for the UISS score. Stratified analysis suggested that the association is more pronounced among patients with low and intermediate-risk disease defined by the UISS score. High ST6Gal-I expression is a potential independent adverse predictor of survival and recurrence in ccRCC patients, and the prognostic value is most prominent in those with low and intermediate-risk disease defined by the UISS score.