Research Mentor and Department
Dr. Michael F. Romero | Physiology and Biomedical Engineering | Mayo Clinic College of Medicine
Calcium oxalate (CaOx) accounts for >70%of kidney stones, yet why CaOx stones form is poorly understood. While several factors contribute to the stone aggregation and growth, elucidating the roles of oxalate transporters can help demystify this phenomenon. Using a Drosophila model to study the formation and inhibition of CaOx crystals in the fly Malpighian tubule (MT), oxalate transport via dPrestin—the fly Slc26a6 Cl-/Ox2- exchanger was studied using both electrophysiology and MT dissection with CaOx birefringence assays. Here, the fly model suffices as it recapitulates renal oxalate excretion. Additionally, the mammalian dicarboxylate transporter NaDC1 (Indy in Drosophila) was shown to have a protein-protein interaction with Slc26a6 such that oxalate transport is increased [Ohana, 2013, PMID 3785279]. This study sought to test if oxalate transport is altered in the fly model. To control MT perfusion in these studies, a microfluidic device was developed to allow both bath and luminal access while using knockdowns and genetically encoded pH and voltage sensors. Preliminary results from ex vivo MT CaOx assays reveal crystal decreases with either dPrestin or INDY knockdown (RNAi) alone. Voltage clamp experiments will test if co-expression of dPrestin and dINDY (Xenopus oocytes) increase oxalate transport as observed with mammalian clones. This work investigates the mechanisms of CaOx formation in the renal system via two transporters. Further work includes developing a fully functional microfluidic platform for assessing the formation of CaOx in a physiologically accurate renal tubule system.