Zhaoxia Sun PhD
Associate Professor of Genetics
Zebrafish genetics; Cilium; Kidney development; Polycystic kidney disease (PKD); Ciliopathy
We use zebrafish to study polycystic kidney disease (PKD) and other diseases caused by defects in a cell surface organelle called cilium. PKD is a common human genetic disease with severe medical consequences. Currently no directed treatment is available for this disease. Our ultimate goal is to understand cilia-mediated signaling and its role in the etiology of PKD, thus provide insight for rational designing of treatment against this disease and other ciliopathies.
Extensive Research Description
The cilium is a hair like cell surface organelle that is almost ubiquitously present on vertebrate cells. It is believed to function as an antenna for the cell to detect and transduce signals. Not surprisingly, in the past decade, there is an increasing appreciation for the vital role played by this tiny organelle in diverse developmental processes and homeostasis in vertebrates. Consistently, cilia dysgenesis and dysfunction have been linked to a growing list of human diseases ranging from polycystic kidney disease (PKD), cancer, to mental retardation and obesity, collectively referred to as ciliopathies. However, the cilium is also one of the few organelles whose physiology and function remain to be fully interrogated. Despite the amazing structural conservation of this organelle from green algae to human, the function of the cilium has diverged significantly between vertebrates and traditional invertebrate model organisms, including Drosophila and C. elegans.
In contrast to fly and worm, zebrafish shows significant functional conservation of cilia-mediated signaling with mammals. Combined with its amenability to large-scale chemical and genetic screens, the accessibility of cilia in multiple organs and the collection of cilia mutants already available, this feature of zebrafish makes it uniquely positioned as a model system for studying cilia and ciliopathy.
Using a variety of approaches in zebrafish, we are teasing out the mechanisms that govern cilia biogenesis, motility and size and the role of cilia in development and diseases. One disease of particular interest is polycystic kidney disease (PKD). PKD is characterized by the formation of multiple kidney cysts thought to result from over-proliferation of renal epithelial cells. Understanding PKD is of profound medical importance. Striking one in 1000 live births, autosomal dominant form of PKD (ADPKD) is among the most common monogenetic disorders in humans. Aside from kidney transplantation, no directed treatment is available for this disease. Our studies have provided strong evidence for the critical role of the cilium in PKD pathogenesis and suggested HDAC inhibitors as promising candidate drugs for treating PKD. We are expanding our research into the role of cilia in other diseases and are also developing novel tools for studying PKD and cilia in zebrafish.