[Role of uropontin in calcium oxalate lithogenesis]

The formation of calcium oxalate stones involves four phases: nucleation, growth, aggregation and retention. Stone formation is a complex, multifactorial phenomenon involving, among other factors, proteins, some of which play an inhibitory role, while others play a promoting role. The authors studied the role of uropontin. Uropontin is the urinary form of osteopontin. Osteopontin is essentially involved in the mineralisation of bone tissue. Uropontin is secreted in the kidney by epithelial cells of the distal convoluted tubule and loop of Henle. Uropontin has an inhibitory action on the four phases of calcium oxalate crystal formation and is also one of the main constituents of the calcium oxalate stone matrix. A reduction of uropontin expression in epithelial cells induces a reduction of calcium oxalate stone formation. Uropontin is a protein largely involved in the lithogenesis of urinary stones, but its mechanism of action has not yet been fully elucidated.