Abstract: SA-PO471
Protein Phosphatase 1 Alpha Interacts with Polycystin-1 and Regulates Polycystin-1 Targeting to Primary Cilium
Session Information
- Cystic Kidney Diseases: Basic/Translational
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1001 Genetic Diseases of the Kidneys: Cystic
Authors
- Luo, Chong, Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
- Chen, Jianghua, Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
- Zhou, Jing, Brigham & Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States
Background
Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disease, which is mostly caused by mutations in PKD1 or PKD2 genes. However, how mutations in these two genes lead to ADPKD remains partially understood. Recent studies have indicated that defective ciliary trafficking of polycystin-1/2 (PC1/2, encoded by PKD1 and PKD2, respectively) underlies the pathogenesis of a subgroup of ADPKD cases. We have recently identified a novel ciliary targeting sequence (CTS) in the C-terminus of PC1. We found that this CTS interacts with protein phosphatase 1-a (PP1a), a ubiquitously expressed phosphatase in the PPP family. Short hairpin RNA mediated knockdown of PP1a in IMCD3 cells results in reduced PC1 ciliary localization and elongated cilia without affecting GPS cleavage or protein maturation of PC1. Nevertheless, the precise mechanism under which PP1a regulates ciliary targeting of PC1 is still obscure.
Methods
Four PC1 constructs with phosphomimic or phosphodeficient mutantions were transfected into IMCD3 cells and co-stained with cilia marker. HA-tagged PC1 and flag-tagged PP1a were co-transfected into IMCD3 cells and then stained to detect the subcellular localization of PP1a/PC1 complex. PC1 and 2 were co-transfected into PP1a knockdown cells and then the ciliary targeting efficiency of PC1 was analyzed.
Results
Ciliary localization of all the four PC1 mutations was not affected compared with wild type control. PP1a and PC1 do not co-localize on the primary cilium but in the cytosol. Overexpression of PC2 is able to rescue the ciliary targeting defect of PC1 in PP1a knockdown cells.
Conclusion
Preliminary results suggest PP1a bind with PC1 in the cytosol and regulates PC1 trafficking. This regulation is probably not caused by PP1a mediated PC1 dephosphorylation. PP1a might function in this process via modifying PC2, a prerequisite for PC1 targeting to cilia. Further investigation is required to delineate the exact role of PP1a in PC1 trafficking.