Published on 18 May 2014
ORLANDO, FL USA (UroToday.com) - Thomas Chi and colleagues developed a method of screening single gene knockdown candidates for their ability to prevent the formation of urinary stones utilizing Drosophila.
Microdissection facilitates identification and collection of fly stones within the lumen of the Drosophila Malpighian tubule (the functional equivalent of the human renal tubule). In a similar fashion as seen in humans, fly stones frequently obstruct the ureter and result in early death. Utilizing shortened lifespan as a surrogate for stone formation, an unbiased screen of orthologues for human genes known to be associated with nephrolithiasis was undertaken. A double knockdown unbiased screen to identify genes that lengthened lifespan and modulated the stone formation process was developed; microdissection confirmed these results.
Stone formation was associated with a significantly shortened fly lifespan (mean lifespan 60 days with no stones, 3 days with stones, p < 0.05). An unbiased double knockdown screen of more than 80 genes was performed utilizing the GAL4-UAS RNAi system and identified 7 genes that rescued lifespan. Microdissection confirmed that three genes decreased stone formation in the fly, including genes encoding a salt transporter (SLC5A5), a zinc transporter (ZnT35C), and a regulator of oxidative stress (Cyp4d1). These lengthened lifespan to 9, 12, and 11 days (p < 0.05) respectively and significantly modulated the stone formation process.
This is an outstanding study and findings have significant implications of stone disease treatment in the future. A Drosophila urinary stone model was leveraged to perform large-scale genetic screens to identify novel genes that modulate calculi formation. Newly identified genes may represent novel targets that could translate to new therapies to prevent or reduce the formation of urinary stones.
Presented by Thomas Chi, MD at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA
San Francisco, CA USA