The signals that drive kidney development: a view from the fly eye.
OBJECTIVE
Development of the mammalian kidney is a complex process involving numerous signals and signaling pathways. Other complex tissues have benefited enormously from studies in lower, simpler organisms. The present review provides an update on what we have learned from the fruitfly Drosophila melanogaster, and argues that Drosophila is an important but under-utilized organism for study of renal development.


RESULTS
The Malpighian tubules provide renal function to the fly. These require a number of signaling pathways for their development that are also seen in vertebrate kidney development, including the Notch, Ras, and Wnt signaling pathways, as well as nuclear factors such as Krüppel and Cut/Cux-1. Many of these factors are shared between early Malpighian tubule development and ureteric bud formation. The Ret signaling receptor, which is central to mammalian renal development, is poorly understood in flies, although its expression pattern is intriguing. Surprisingly, other signaling factors such as Neph-1, Pax2, and Wilms' tumor suppressor-1 appear to work within later fly retinal development, providing a surprising link between these two disparate tissues.


CONCLUSIONS
Drosophila offers a powerful palate of tools for dissecting developmental processes. Importantly, these tools can often be examined at the level of single cells, permitting us to address issues of differentiation with high resolution. If we are to take full advantage of Drosophila, however, then we must target specific issues and gain a better understanding of the details of Malpighian tubule development.
Cagan
Ross
R
Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA. cagan@molecool.wustl.edu
D000818:Animals; D004331:Drosophila melanogaster / Q000254:growth & development / Q000502:physiology*; D007668:Kidney / Q000254:growth & development*; D008317:Malpighian Tubules / Q000254:growth & development / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*