Kidney stone disease can be modeled in Drosophila by using food supplemented with sodium oxalate, ethylene glycol, hydroxy-L-proline, or other chemicals. Dose-dependent calcium oxalate crystal formation is visible as early as 24 to 48 hours in the Malpighian tubules of flies fed increasing concentrations of sodium oxalate. These systems have allowed assessment of therapeutic regimens and modulating genes. In particular, the role of Dmel\Prestin, which is orthologous to a number of human genes in solute carrier family 26, has been investigated.
Based on reports that melamine-tainted food can induce renal stones, this system has been used to assess the effect of melamine on crystal formation in Drosophila. Dose-dependent crystal formation is observed. The composition of crystal in Malphigian tubules is of mixed type; calcium oxalate is not the major crystal induced by melamine.
Uric acid is another agent which is a risk factor for kidney stones in humans, especially when its levels are elevated due to metabolic dysfunction or excessive consumption of purines in the diet. Unlike humans, Drosophila use the enzyme urate oxidase to eliminate uric acid. Knocking down Dmel\Uro generates a "humanized" fly which models symptoms of elevated uric acid in humans.
An assay using cultured dissected Malpighian tubules has also been developed to assess efficacy and mechanism of therapeutic compounds.
See also the human disease model report for 'xanthinuria, type I' (FBhh0000095).
[updated Feb. 2020 by FlyBase; FBrf0222196]
Kidney stones (renal lithiasis, nephrolithiasis) are hard deposits made of minerals and salts that form inside the kidneys. (https://www.mayoclinic.org/diseases-conditions/kidney-stones/symptoms-causes/syc-20355755)
About 5% of American women and 12% of men will develop a kidney stone at some time in their life; approximately 80% of stones are composed of calcium oxalate (CaOx) and calcium phosphate (CaP). (Coe et al., 2005; pubmed:16200192)
