Abstract: TH-PO673
Contribution of Myo-Inositol Oxygenase in Age: Rage Mediated Renal Tubulo-Interstitial Injury
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
- Sharma, Isha, NORTHWESTERN UNIVERSITY, CHICAGO, Illinois, United States
- Tupe, Rashmi Santosh, Northwestern University, Chicago, Illinois, United States
- Kanwar, Yashpal S., Northwestern University Medical School, Chicago, Illinois, United States
Background
Advanced glycation end products (AGEs) have been postulated to play a critical role in pathogenesis of diabetic nephropathy (DN). Myo-inositol Oxygenase (MIOX), a proximal tubular enzyme, which has been implicated in tubulo-interstitial injury in the context of DN.
Methods
Aim of the present study was to investigate the effect of AGEs on MIOX expression and to delineate the mechanisms that lead to tubulo-interstitial injury. To test this we examined the status of MIOX, RAGE and relevant cellular signaling pathway activated following AGE:RAGE interaction in cultured tubular cells and kidneys of AGE-BSA treated mice.
Results
Using solid phase binding assay an enhanced binding of RAGE with AGE-BSA, -laminin and -collagen IV was observed compared to non-glycated proteins. AGE-BSA treatment led to an increased MIOX activity and its expression in a time- and dose-dependent manner. AGE-BSA also increased MIOX promoter activity. This was associated with activation of various signaling kinases of PI3K-AKT pathway and increased expression of NF-κB, TGF-β and fibronectin. Treatment with MIOX- and RAGE-siRNA negatively impacted the activation of PI3K-AKT signaling cascade and expression of fibronectin, NF-κB and TGF-β. Interestingly, concomitant with the up-regulation of MIOX there was an increased generation of reactive oxygen species (ROS), which could be abrogated with the MIOX- or RAGE-siRNA treatment. In vivo the kidneys of mice treated with AGE-BSA for 2 weeks had significantly high urinary AC ratio, up-regulation of MIOX, RAGE and NF-κB along with influx of monocytes in the tubulo-interstitium, increased expression of MCP-1, IL-6 and fibronectin, and generation of ROS. These molecular derangements were abrogated with the concomitant treatment of inhibitors MIOX or RAGE (D-glucarate & FPS-ZM1).
Conclusion
These in vivo and in vitro studies support a critical role of AGE:RAGE interaction in the activation of PI3K-AKT pathway and up-regulation of MIOX; as a result of which there is an excessive generation of ROS, increased expression of NF-κB, inflammatory cytokines, TGF-β and fibronectin. Collectively, these observations highlight the importance of MIOX in the contribution towards tubulo-interstitial injury in DN.
Funding
- NIDDK Support