Urological Research

, Volume 39, Issue 4, pp 269–282

Calcium oxalate monohydrate aggregation induced by aggregation of desialylated Tamm-Horsfall protein

  • Pragasam Viswanathan
  • Jeffrey D. Rimer
  • Ann M. Kolbach
  • Michael D. Ward
  • Jack G. Kleinman
  • Jeffrey A. Wesson
Original Paper

DOI: 10.1007/s00240-010-0353-7

Cite this article as:
Viswanathan, P., Rimer, J.D., Kolbach, A.M. et al. Urol Res (2011) 39: 269. doi:10.1007/s00240-010-0353-7

Abstract

Tamm-Horsfall protein (THP) is thought to protect against calcium oxalate monohydrate (COM) stone formation by inhibiting COM aggregation. Several studies reported that stone formers produce THP with reduced levels of glycosylation, particularly sialic acid levels, which leads to reduced negative charge. In this study, normal THP was treated with neuraminidase to remove sialic acid residues, confirmed by an isoelectric point shift to higher pH. COM aggregation assays revealed that desialylated THP (ds-THP) promoted COM aggregation, while normal THP inhibited aggregation. The appearance of protein aggregates in solutions at ds-THP concentrations ≥1 μg/mL in 150 mM NaCl correlated with COM aggregation promotion, implying that ds-THP aggregation induced COM aggregation. The aggregation-promoting effect of the ds-THP was independent of pH above its isoelectric point, but was substantially reduced at low ionic strength, where protein aggregation was much reduced. COM aggregation promotion was maximized at a ds-THP to COM mass ratio of ~0.025, which can be explained by a model wherein partial COM surface coverage by ds-THP aggregates promotes crystal aggregation by bridging opposing COM surfaces, whereas higher surface coverage leads to repulsion between adsorbed ds-THP aggregates. Thus, desialylation of THP apparently abrogates a normal defensive action of THP by inducing protein aggregation, and subsequently COM aggregation, a condition that favors kidney stone formation.

Keywords

Sialic acidTHPCrystal aggregationProtein aggregationCalcium oxalateKidney stone

Supplementary material

240_2010_353_MOESM1_ESM.doc (674 kb)
Supplementary material (DOC 674 kb)

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Pragasam Viswanathan
    • 1
    • 3
  • Jeffrey D. Rimer
    • 2
    • 4
  • Ann M. Kolbach
    • 1
  • Michael D. Ward
    • 2
  • Jack G. Kleinman
    • 1
  • Jeffrey A. Wesson
    • 1
  1. 1.The Nephrology Division of the Medical College of WisconsinDepartment of Veterans Affairs Medical CenterMilwaukeeUSA
  2. 2.Department of Chemistry, Molecular Design InstituteNew York UniversityNew YorkUSA
  3. 3.Renal Research Lab, SBST, Center for Biomedical ResearchVIT UniversityVelloreIndia
  4. 4.Department of Chemical and Biomolecular EngineeringUniversity of HoustonHoustonUSA