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Sialic acid and crystal binding
C F Verkoelen1, B G van der Boom, D J Kok
1Erasmus Urological Stone Treatment and Research (Eurostarr), Erasmus University, Rotterdam, The Netherlands. Verkoelen@uro.fgg.eurnl
Kidney International
|March 18, 2000
Summary
Cell surface sialic acid plays a key role in calcium oxalate monohydrate crystal adherence to kidney cells. Sialic acid presentation on immature cells facilitates crystal binding, suggesting its importance in kidney stone formation.
Area of Science:
- Cell Biology
- Biochemistry
- Nephrology
Background:
- Investigated the role of cell surface sialic acid in calcium oxalate monohydrate (COM) crystal adherence to Madin-Darby canine kidney (MDCK) cells.
- Focused on undifferentiated (crystal-binding) and maturated (noncrystal-binding) MDCK cells.
Purpose of the Study:
- To elucidate the function of cell surface sialic acid in COM crystal adhesion to kidney cells.
- To understand how sialic acid expression changes during epithelial cell maturation and its impact on crystal binding.
Main Methods:
- Utilized lectins (MALII, SNA, PNA) to analyze cell surface oligosaccharides during epithelial development.
- Assessed the effect of neuraminidase treatment on COM crystal binding using [14C]COM crystals.
- Monitored sialic acid release via metabolic labeling with [3H]glucosamine.
Main Results:
- Sialic acids, linked via alpha 2,3 and alpha 2,6 bonds, are expressed at different stages of MDCK cell development.
- Neuraminidase treatment significantly reduced COM crystal binding to immature cells.
- Mature cells exhibit higher sialylation, and PNA binding indicates sialic acid presence on terminal galactose units, which is revealed by neuraminidase treatment in mature cells.
Conclusions:
- Sialic acids on immature cells may be oriented to favor COM crystal interactions.
- Alternatively, sialic acids might facilitate the exposure of other crystal-binding molecules on the cell surface.