Abstract: TH-PO689
MDM2 Contributes to High Glucose-Induced Glomerular Mesangial Cell Proliferation and Extracellular Matrix Accumulation via Notch1 Signaling
Session Information
- Diabetes Mellitus and Obesity: Basic - Experimental - I
November 02, 2017 | Location: Hall H, Morial Convention Center
Abstract Time: 10:00 AM - 10:00 AM
Category: Diabetes
- 501 Diabetes Mellitus and Obesity: Basic - Experimental
Authors
- Lei, Chun-Tao, Union Hospital, Huazhong University of Science and Technology, Wuhan Hubei Provicne, China
- Su, Hua, Union Hospital, Huazhong University of Science and Technology, Wuhan Hubei Provicne, China
- Zhang, Chun, Union Hospital, Huazhong University of Science and Technology, Wuhan Hubei Provicne, China
Background
Murine double minute 2 (MDM2), an E3-ubiquitin ligase, is critical for various biological functions and its dysregulation is involved in tumorigenesis. Previous data have documented an indispensable role of MDM2 in kidney homeostasis and disorders. However, its role in glomerular mesangial cell (GMC) proliferation and extracellular matrix (ECM) accumulation under hyperglycemia remains unclear.
Methods
In vitro study, rat mesangial cell line was employed, and subjected to different treatments. RNA interfere and Nutlin-3a treatment were utilized to knockdown MDM2 expression and block MDM2-p53 interaction respectively. Diabetic mice model was established by intraperitoneal injection of streptozotocin (STZ) and intraperitoneal administration of Nutlin-3a was adopted to disrupt the in vivo binding between MDM2 and p53.
Results
In the present study, we found MDM2 protein level is upregulated in high glucose-cultured GMCs. Knocking down MDM2 by siRNA attenuates high glucose-induced ECM accumulation and cell proliferation. However, MDM2-p53 interaction blocker Nutlin-3a, cannot protect diabetic mice from renal impairment not only in vivo but also has no benefit on high glucose-induced ECM accumulation in vitro. Intriguingly, we found Notch1 signaling is activated in GMCs with high glucose exposure which is obviously attenuated by MDM2 depletion. However, Numb, another substrate of MDM2 which suppresses Notch1 signaling, is not involved in the MDM2 mediated Notch1 regulation. Lastly, our findings revealed that MDM2 binds with and ubiquitinates Notch1 intracellular domain (NICD1) , however the ubiquitination status of NICD1 does not lead it to degradation but activates its downstream gene expression.
Conclusion
Collectively, our data propose a pivotal role of MDM2 in high glucose-induced GMC proliferation and ECM accumulation, through modulating the activation of Notch1 signaling in an ubiquitination-dependent but p53-independent way.
Funding
- Government Support - Non-U.S.