Characterization of Tamm-Horsfall protein in a rat nephrolithiasis model.

Abstract

PURPOSE:

The role of Tamm-Horsfall protein in calcium oxalate stone formation is controversial. It is unclear whether Tamm-Horsfall protein has a role in crystallization. If it does, does it act as an inhibitor or promoter of crystallization? To elucidate the nature of its involvement we characterized Tamm-Horsfall protein in a rat model of calcium oxalate nephrolithiasis by in vivo and in vitro techniques.

MATERIALS AND METHODS:

Calcium oxalate nephrolithiasis was induced in male Sprague-Dawley rats. The amino acid and carbohydrate composition of Tamm-Horsfall protein from normal rats and those with nephrolithiasis was determined. The Tamm-Horsfall protein gene and protein expression in the kidneys were examined by in situ hybridization and immunohistochemistry. Furthermore, the interaction of Tamm-Horsfall protein and calcium oxalate crystals was assessed by an in vitro crystal aggregation assay.

RESULTS:

Tamm-Horsfall protein from rats with nephrolithiasis was biochemically similar to that from normal rats. Although Tamm-Horsfall protein was associated with crystal deposits in the renal papillae of rats with nephrolithiasis, Tamm-Horsfall protein messenger RNA expression in the kidneys remained unchanged. In each group Tamm-Horsfall protein inhibited calcium oxalate crystal aggregation by 47%, indicating no change in functional capabilities.

CONCLUSIONS:

The results of this study indicate that urinary excretion, and the biochemical nature and functional capabilities of Tamm-Horsfall protein remain unchanged during experimental calcium oxalate nephrolithiasis. Although staining for Tamm-Horsfall protein was evident in the papillae of rats with nephrolithiasis, the site of Tamm-Horsfall protein synthesis remained cells of the thick ascending limbs of the loop of Henle.

• Authors: J A Gokhale, P A Glenton, S R Khan
• Journal: The Journal of urology (J Urol) Vol. 166 Issue 4 Pg. 1492-7 (Oct 2001) ISSN: 0022-5347 [Print] United States
• PMID: 11547119 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Mucoproteins
• RNA, Messenger
• Umod protein, rat
• Uromodulin

Topics

• Animals
• Crystallization
• Kidney Calculi (etiology)
• Male
• Mucoproteins (genetics, metabolism)
• RNA, Messenger (analysis)
• Rats
• Rats, Sprague-Dawley
• Uromodulin