Abstract: SA-PO375
MDM2 Subcellular Trafficking Is Involved in the AKD to CKD Progression Induced by Repeated Cisplatin Exposure
Session Information
- CKD: Risk Factors for Incidence and Progression - III
November 04, 2017 | Location: Hall H, Morial Convention Center
Abstract Time: 10:00 AM - 10:00 AM
Category: Chronic Kidney Disease (Non-Dialysis)
- 301 CKD: Risk Factors for Incidence and Progression
Author
- Su, Hua, Huazhong Science and Technology University, Wuhan, China
Background
Repeated cisplatin (CP) administration frequently leads to the development from acute kidney disease (AKD) to chronic kidney disease (CKD). During above pathogenic process the tubular epithelial cell (TEC) damage is the cardinal event. MDM2 is an E3 ligase and participates in multiple pathophysiologic responses. Previously our studies revealed that MDM2 not only involves in AKD but also accounts for CKD by promoting fibroblast activation. However, the role of MDM2 in repeated CP exposure induced AKD to CKD transition is unclear.
Methods
AKD to CKD mice model was established by intraperitoneal injection of CP (8mg/Kg) once a week. The mice were grouped into 1CP, 2CP, 3CP and 4CP according to the times of CP administration. 7 days after the final injection the mice were sacrificed and kidney cortex was collected. Immunostaining and sucrose gradient ultracentrifugation were utilized to label or isolate subcellular organelles. Immunoprecipitation was employed to examine the interaction between MDM2 with p53 or NHERF1, as well as the ubiquitination of p53 and NHERF1.
Results
We successfully established the CP-induced AKD to CKD mice model which was proved by the increased NAGL and KIM-1 expression in 2 CP group with later upregulated α-SMA, Collagen 3 and serum creatinine in 3CP and 4CP groups. Our data shown in physiological state MDM2 predominantly distributes in nuclei and binds with p53, however after first time of CP administration MDM2 moves from nuclei to cytoplasm along with decreased interaction of p53 and upregulated p53 expression. Furthermore, after 3 and 4 times of CP injection, we found cytoplasmic MDM2 further transports to cell membrane and interacts with NHERF1, a negative regulator of PDGF-BB/PDGFR-β axis, and which leads to the enhanced ubiquitination of NHERF1. Consequently, the abundance of NHERF1 minimized with the activation of PDGF-BB/PDGFR-β signaling, a well-known cytokine pathway involved in CKD development via autocrine as well as paracrine manner.
Conclusion
Repeated CP administration initiates the MDM2 trafficking form nuclei to cytoplasm, and eventually move to the cell membrane where MDM2 binds with and ubiquitinates NHERF1. Consequently, NHERF1 is degraded and PDGF-BB/PDGFR-β signaling is activated.
Funding
- Government Support - Non-U.S.