Characterization of interactions involving the polycystic kidney disease-causing proteins: SamCystin and Bicc1

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Rodent models, including the Han:SPRD-Cy rat and the jcpk mouse, have been useful for identifying and characterizing genes that cause Polycystic Kidney Disease. The Han:SPRD-Cy rat model carries a mutation that affects the Anks6 gene product, SamCystin, while the disease-causing mutation in the jcpk mouse severely truncates the Bicaudal C (Bicc1) protein. The role of these proteins in the mammalian kidney is unknown. Immunolocalization studies demonstrated that SamCystin and Bicc1 colocalize in the cytoplasm of cultured kidney cells. Immunoprecipitation results showed that SamCystin self-associates, Bicc1 and SamCystin interact, and the mutation responsible for PKD in the Han:SPRD-Cy rat disrupts the self-association of SamCystin but not the Bicc1-SamCystin interaction. Additionally, real time PCR assays were used to compare relative expression levels of 9 PKD-related genes between normal and cystic kidneys from Cy PKD rats. We found that mRNA levels of Nek1 and Hnf1[alpha] were significantly reduced in the cystic kidneys. Collectively, these results begin to provide information that will help elucidate the role of SamCystin and Bicc1 in the molecular pathways leading to cystogenesis in the kidney.