Abstract: SA-PO113
PDK4/SMAD3/HIF-1α Circle Enhances AKI Susceptibility in Diabetic Kidney Disease (DKD) through Fibrosis
Session Information
- AKI: Metabolism and Cell Death
October 26, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Authors
- Guo, Jianbo, School of Chinese Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- Li, Haidi, Anhui Medical University, Hefei, Anhui, China
- Wang, Yifan, School of Chinese Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- Shao, Baoyi, School of Chinese Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- Wang, Jianan, Anhui Medical University, Hefei, Anhui, China
- Chen, Hai-Yong, School of Chinese Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
Background
AKI poses significant risks of mortality and organ dysfunction, especially in DKD. Excessive accumulation of ROS is implicated in AKI pathogenesis. Pyruvate dehydrogenase complex is phosphorylated by pyruvate dehydrogenase kinase 4 (PDK4), leading to increased ROS. Previous studies have revealed that TGF-β/SMAD3 signaling activation promotes fibrosis in DKD, while HIF-1α could be activated by phosphorylated SMAD3. However, the regulatory relationship among PDK4, SMAD3, and HIF-1α in AKI susceptibility in DKD remains unclear.
Methods
The ischemia/reperfusion (I/R) induced AKI models were conducted in db/m and db/db mice. Kidney epithelial cells were treated high glucose with/without the hypoxia and reoxygenation (HG + H/R) conditions. Chromatin immunoprecipitation (ChIP)-qPCR were utilized to identify the promoter binding site at gene transcriptional level. Gain to loss-function of inter-players were used to further confirm the results.
Results
Oxidative stress levels were significantly increased in vivo and in vitro models, including increased SOD and GSH levels and decreased MDA levels. I/R-induced AKI in db/db mice and the HG + H/R model exhibited significant elevations in PDK4, p-SMAD3, HIF-1α, fibronectin and KIM-1. Inhibition of PDK4 by using PDK4-IN-1 hydrochloride down-regulated the expressions of p-SMAD3, HIF-1α, fibronectin and KIM-1. Inhibition of p-SMAD3 by using SIS3 down-regulated the expressions of PDK4, HIF-1α, fibronectin and KIM-1. Inhibition of HIF-1α by using YC-1 down-regulated the expressions of PDK4, p-SMAD3, Fibronectin and KIM-1. Besides, overexpressed PDK4, p-SMAD3, or HIF-1α by constructing plasmids up-regulated the expressions of other genes. ChIP results showed that p-SMAD3 protein could bind to HIF-1α promoter and up-regulate HIF-1α transcription.
Conclusion
PDK4, mediated by SMAD3, increases HIF-1α transcription and further up-regulate the PDK4 expression. The circular pathway increases the level of fibrosis and enhances AKI susceptibility in DKD.
Funding
- Government Support – Non-U.S.