Carl W. Gottschalk Scholar of the ASN Foundation for Kidney Research

This ASN career development grant proposal supports the candidate’s career goals of studying dysregulation of ciliary PKD2 ion channels in ADPKD-2 (autosomal dominant polycystic kidney disease, type 2). The candidate has developed and published two innovative techniques to measure ion channel events in the primary cilium, which distinguishes his research from others in the field3,5. First, the candidate developed electrophysiology methods that measure the membrane potential of the cilia compartment and ionic flux across the membrane. Second, the candidate applied a genetically encoded ratiometric calcium sensor to detect calcium changes within the cilium. The candidate has demonstrated the effectiveness of these methods, identifying the PKD1-L1/2-L1 ion channel present in the primary cilium of non-renal cells. In the candidate’s unpublished preliminary work, he has identified PKD2 as the cilia ion channel of inner medullary kidney collecting duct epithelial cells and established heterologous methods for studying ADPKD mutant forms of PKD2 in cilia using direct electrophysiology methods. Little is known regarding the functional effect of ADPKD mutations on PKD2 cilia channels and there no drug treatment to delay kidney cyst formation. For the duration of the ASN grant proposal, the candidate will apply these methods to determine the effect of ADPKD-2 mutations on PKD2 channel function and screen for pharmacological modulators of PKD2. The outcome of Specific Aim 1 dovetails with Specific Aim 2, where a rationale for potential ADPKD treatment will depend on the type of PKD2 channel effect (gain- or loss-of-function) present and on the availability of activators and antagonists. Most recently, the candidate published the first structure of PKD2 using cryo-EM and identified the calcium regulatory mechanism of PKD2-L14,10. In the third specific aim, the candidate will carry out x-ray crystallography of PKD2 variants to determine the structural impact of ADPKD-2 mutations and the receptor binding sites of PKD2-drug complexes. Towards achieving his long term goals of understanding the mechanisms underlying cyst development and novel mutations associated with ADPKD, the candidate will undertake training in genomic and bioinformatic methods necessary for isolating heritable genetic factors that may lead to the development of ADPKD. In addition, the candidate will receive FRET training to dissect the molecular mechanisms that alter PKD2 function. The candidate is well-qualified to carry out the short- and long-term goals described above. He has over ten years of experience in ion channel biology, structural biophysics and has spent considerable effort learning and developing methods to study PKD channels and primary cilia. If awarded, the candidate will use these funds to execute these aims to the fullest and establish a NIH-supported research lab focused on ADPKD.